WorldWideScience

Sample records for satellite-derived estimates ta

  1. Estimating Ground-Level Particulate Matter (PM) Concentration using Satellite-derived Aerosol Optical Depth (AOD)

    Science.gov (United States)

    Park, Seohui; Im, Jungho

    2017-04-01

    Atmospheric aerosols are strongly associated with adverse human health effects. In particular, particulate matter less than 10 micrometers and 2.5 micrometers (i.e., PM10 and PM2.5, respectively) can cause cardiovascular and lung diseases such as asthma and chronic obstructive pulmonary disease (COPD). Air quality including PM has typically been monitored using station-based in-situ measurements over the world. However, in situ measurements do not provide spatial continuity over large areas. An alternative approach is to use satellite remote sensing as it provides data over vast areas at high temporal resolution. The literature shows that PM concentrations are related with Aerosol Optical Depth (AOD) that is derived from satellite observations, but it is still difficult to identify PM concentrations directly from AOD. Some studies used statistical approaches for estimating PM concentrations from AOD while some others combined numerical models and satellite-derived AOD. In this study, satellite-derived products were used to estimate ground PM concentrations based on machine learning over South Korea. Satellite-derived products include AOD from Geostationary Ocean Color Imager (GOCI), precipitation from Tropical Rainfall Measuring Mission (TRMM), soil moisture from AMSR-2, elevation from Shuttle Radar Topography Mission (SRTM), and land cover, land surface temperature and normalized difference vegetation index (NDVI) from Moderate Resolution Imaging Spectroradiometer (MODIS). PM concentrations data were collected from 318 stations. A statistical ordinary least squares (OLS) approach was also tested and compared with the machine learning approach (i.e., random forest). PM concentration was estimated during spring season (from March to May) in 2015 that typically shows high concentration of PM. The randomly selected 80% of data were used for model calibration and the remaining 20% were used for validation. The developed models were further tested for prediction of PM

  2. Comparative Study of Ground Measured, Satellite-Derived, and Estimated Global Solar Radiation Data in Nigeria

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    Boluwaji M. Olomiyesan

    2016-01-01

    Full Text Available In this study, the performance of three global solar radiation models and the accuracy of global solar radiation data derived from three sources were compared. Twenty-two years (1984–2005 of surface meteorological data consisting of monthly mean daily sunshine duration, minimum and maximum temperatures, and global solar radiation collected from the Nigerian Meteorological (NIMET Agency, Oshodi, Lagos, and the National Aeronautics Space Agency (NASA for three locations in North-Western region of Nigeria were used. A new model incorporating Garcia model into Angstrom-Prescott model was proposed for estimating global radiation in Nigeria. The performances of the models used were determined by using mean bias error (MBE, mean percentage error (MPE, root mean square error (RMSE, and coefficient of determination (R2. Based on the statistical error indices, the proposed model was found to have the best accuracy with the least RMSE values (0.376 for Sokoto, 0.463 for Kaduna, and 0.449 for Kano and highest coefficient of determination, R2 values of 0.922, 0.938, and 0.961 for Sokoto, Kano, and Kaduna, respectively. Also, the comparative study result indicates that the estimated global radiation from the proposed model has a better error range and fits the ground measured data better than the satellite-derived data.

  3. Evaluation of a physically-based snow model with infrared and microwave satellite-derived estimates

    Science.gov (United States)

    Wang, L.

    2013-05-01

    Snow (with high albedo, as well as low roughness and thermal conductivity) has significant influence on the land-atmosphere interactions in the cold climate and regions of high elevation. The spatial and temporal variability of the snow distribution on a basin scale greatly determines the timing and magnitude of spring snowmelt runoff. For improved water resources management, a physically-based distributed snow model has been developed and applied to the upper Yellow River Basin to provide the outputs of snow variables as well as streamflows from 2001 to 2005. Remotely-sensed infrared information from MODIS satellites has been used to evaluate the model's outputs of spatially-distributed snow cover extent (SCE) and land surface temperature (LST); while the simulated snow depth (SD) and snow water equivalent (SWE) have been compared with the microwave information from SSM/I and AMSR-E satellites. In general, the simulated streamflows (including spring snowmelt) agree fairly well with the gauge-based observations; while the modeled snow variables show acceptable accuracies through comparing to various satellite-derived estimates from infrared or microwave information.;

  4. Utilization of satellite-derived estimates of meteorological and land surface characteristics in the Land Surface Model for vast agricultural region territory

    Science.gov (United States)

    Muzylev, Eugene; Startseva, Zoya; Uspensky, Alexander; Volkova, Elena

    2015-04-01

    data from named radiometers. All technologies have been adapted to the study area. Verification of the AVHRR- and MODIS-derived LST estimates has been performed through comparison with ground-measured temperatures and analogous estimates obtained from remaining sensors. The reliability of SEVIRI-derived LST estimates has been verified by comparison with similar synchronous SEVIRI-derived estimates produced in LSA SAF (Land Surface Analysis Satellite Applications Facility, Lisbon, Portugal). Correctness of LAI estimates has been confirmed by comparing time behavior of satellite- and ground-based LAI during vegetation season. Satellite-derived estimates of precipitation have been built using the Multi Threshold Method (MTM) developed for automatic pixel-by-pixel classification of AVHRR and SEVIRI data. The method is intended for the cloud detection and identification of its types, estimation of the maximum liquid water content and water content of the cloud layer, allocation of precipitation zones and determination of instantaneous maximum intensities of precipitation in the pixel range around the clock throughout the year independently of the land surface type. Measurement data from five AVHRR channels or from eleven SEVIRI channels as well as their differences have been used in the MTM as predictors. To validate the methodology, ground-based observation data on daily precipitation sums at agricultural meteorological stations of the study region have been used. The probability of correct precipitation zone detection from satellite data is at least 70% (80-85% in some cases) when compared with ground-based observations. In the frame of this approach the transition from the rainfall intensity estimation to the calculation of their daily values has been accomplished. In the study the AVHRR- and SEVIRI-derived daily, monthly and annual sums of precipitation for the region of interest have been calculated. The daily and monthly sums have been found to be in good agreement

  5. Modeling of groundwater draft based on satellite-derived crop acreage estimation over an arid region of northwest India

    Science.gov (United States)

    Bhadra, Bidyut Kumar; Kumar, Sanjay; Paliwal, Rakesh; Jeyaseelan, A. T.

    2016-11-01

    Over-exploitation of groundwater for agricultural crops puts stress on the sustainability of natural resources in the arid region of Rajasthan state, India. Hydrogeological study of groundwater levels of the study area during the pre-monsoon (May to June), post-monsoon (October to November) and post-irrigation (February to March) seasons of 2004-2005 to 2011-2012 shows a steady decline of groundwater levels at the rate of 1.28-1.68 m/year, mainly due to excessive groundwater draft for irrigation. Due to the low density of the groundwater observation-well network in the study area, assessment of groundwater draft, and thus groundwater resource management, becomes a difficult task. To overcome the situation, a linear groundwater draft model (LGDM) has been developed based on the empirical relationship between satellite-derived crop acreage and the observed groundwater draft for the year 2003-2004. The model has been validated for a decade, during three year-long intervals (2005-2006, 2008-2009 and 2011-2012) using groundwater draft, estimated through a discharge factor method. Further, the estimated draft was validated through observed pumping data from random sampled villages (2011-2012). The results suggest that the developed LGDM model provides a good alternative to the estimation of groundwater draft based on satellite-based crop area in the absence of groundwater observation wells in arid regions of northwest India.

  6. Steady state estimation of soil organic carbon using satellite-derived canopy leaf area index

    Science.gov (United States)

    Fang, Yilin; Liu, Chongxuan; Huang, Maoyi; Li, Hongyi; Leung, L. Ruby

    2014-12-01

    Estimation of soil organic carbon (SOC) stock using models typically requires long term spin-up of the carbon-nitrogen (CN) models, which has become a bottleneck for global modeling. We report a new numerical approach to estimate global SOC stock that can alleviate long spin-up. The approach uses satellite-based canopy leaf area index (LAI) and takes advantage of a reaction-based biogeochemical module—Next Generation BioGeoChemical Module (NGBGC) that was recently developed and incorporated in version 4 of the Community Land Model (CLM4). Although NGBGC uses the same CN mechanisms as in CLM4CN, it can be easily configured to run prognostic or steady state simulations. The new approach was applied at point and global scales and compared with SOC derived from spin-up by running NGBGC in the prognostic mode, and SOC from the Harmonized World Soil Database (HWSD). The steady state solution is comparable to the spin-up value when the satellite LAI is close to that from the spin-up solution, and largely captured the global variability of the HWSD SOC across the different dominant plant functional types (PFTs). The correlation between the simulated and HWSD SOC was, however, weak at both point and global scales, suggesting the needs for improving the biogeochemical processes described in CLM4 and updating HWSD. Besides SOC, the steady state solution also includes all other state variables simulated by a spin-up run, which makes the tested approach a promising tool to efficiently estimate global SOC distribution and evaluate and compare multiple aspects simulated by different CN mechanisms in the model.

  7. Estimation efficiency of usage satellite derived and modelled biophysical products for yield forecasting

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    Kolotii, Andrii; Kussul, Nataliia; Skakun, Sergii; Shelestov, Andrii; Ostapenko, Vadim; Oliinyk, Tamara

    2015-04-01

    Efficient and timely crop monitoring and yield forecasting are important tasks for ensuring of stability and sustainable economic development [1]. As winter crops pay prominent role in agriculture of Ukraine - the main focus of this study is concentrated on winter wheat. In our previous research [2, 3] it was shown that usage of biophysical parameters of crops such as FAPAR (derived from Geoland-2 portal as for SPOT Vegetation data) is far more efficient for crop yield forecasting to NDVI derived from MODIS data - for available data. In our current work efficiency of usage such biophysical parameters as LAI, FAPAR, FCOVER (derived from SPOT Vegetation and PROBA-V data at resolution of 1 km and simulated within WOFOST model) and NDVI product (derived from MODIS) for winter wheat monitoring and yield forecasting is estimated. As the part of crop monitoring workflow (vegetation anomaly detection, vegetation indexes and products analysis) and yield forecasting SPIRITS tool developed by JRC is used. Statistics extraction is done for landcover maps created in SRI within FP-7 SIGMA project. Efficiency of usage satellite based and modelled with WOFOST model biophysical products is estimated. [1] N. Kussul, S. Skakun, A. Shelestov, O. Kussul, "Sensor Web approach to Flood Monitoring and Risk Assessment", in: IGARSS 2013, 21-26 July 2013, Melbourne, Australia, pp. 815-818. [2] F. Kogan, N. Kussul, T. Adamenko, S. Skakun, O. Kravchenko, O. Kryvobok, A. Shelestov, A. Kolotii, O. Kussul, and A. Lavrenyuk, "Winter wheat yield forecasting in Ukraine based on Earth observation, meteorological data and biophysical models," International Journal of Applied Earth Observation and Geoinformation, vol. 23, pp. 192-203, 2013. [3] Kussul O., Kussul N., Skakun S., Kravchenko O., Shelestov A., Kolotii A, "Assessment of relative efficiency of using MODIS data to winter wheat yield forecasting in Ukraine", in: IGARSS 2013, 21-26 July 2013, Melbourne, Australia, pp. 3235 - 3238.

  8. Estimation of glacier mass balance: An approach based on satellite-derived transient snowlines and a temperature index driven by meteorological observations

    Science.gov (United States)

    Tawde, S. A.; Kulkarni, A. V.; Bala, G.

    2015-12-01

    In the Himalaya, large area is comprised of glaciers and seasonal snow, mainly due to its high elevated mountain ranges. Long term and continuous assessment of glaciers in this region is important for climatological and hydrological applications. However, rugged terrains and severe weather conditions in the Himalaya lead to paucity in field observations. Therefore, in recent decades, glacier dynamics are extensively monitored using remote sensing in inaccessible terrain like Himalaya. Estimation of glacier mass balance using empirical relationship between mass balance and area accumulation ratio (AAR) requires an accurate estimate of equilibrium-line altitude (ELA). ELA is defined as the snowline at the end of the hydrological year. However, identification of ELA, using remote sensing is difficult because of temporal gaps, cloud cover and intermediate snowfall on glaciers. This leads to large uncertainty in glacier mass-balance estimates by the conventional AAR method that uses satellite-derived highest snowline in ablation season as an ELA. The present study suggests a new approach to improve estimates of ELA location. First, positions of modelled snowlines are optimized using satellite-derived snowlines in the early melt season. Secondly, ELA at the end of the glaciological year is estimated by the melt and accumulation models driven using in situ temperature and precipitation records. From the modelled ELA, mass balance is estimated using the empirical relationship between AAR and mass balance. The modelled mass balance is validated using field measurements on Chhota Shigri and Hamtah glaciers, Himachal Pradesh, India. The new approach shows a substantial improvement in glacier mass-balance estimation, reducing bias by 46% and 108% for Chhota Shigiri and Hamtah glaciers respectively. The cumulative mass loss reconstructed from our approach is 0.85 Gt for nine glaciers in the Chandra basin from 2001 to 2009. The result of the present study is in agreement with

  9. SACRA – global data sets of satellite-derived crop calendars for agricultural simulations: an estimation of a high-resolution crop calendar using satellite-sensed NDVI

    Directory of Open Access Journals (Sweden)

    S. Kotsuki

    2015-01-01

    Full Text Available To date, many studies have performed numerical estimations of food production and agricultural water demand to understand the present and future supply–demand relationship. A crop calendar (CC is an essential input datum to estimate food production and agricultural water demand accurately with the numerical estimations. CC defines the date or month when farmers plant and harvest in cropland. This study aims to develop a new global data set of a satellite-derived crop calendar for agricultural simulations (SACRA and reveal advantages and disadvantages of the satellite-derived CC compared to other global products. We estimate global CC at a spatial resolution of 5 min (≈10 km using the satellite-sensed NDVI data, which corresponds well to vegetation growth and death on the land surface. We first demonstrate that SACRA shows similar spatial pattern in planting date compared to a census-based product. Moreover, SACRA reflects a variety of CC in the same administrative unit, since it uses high-resolution satellite data. However, a disadvantage is that the mixture of several crops in a grid is not considered in SACRA. We also address that the cultivation period of SACRA clearly corresponds to the time series of NDVI. Therefore, accuracy of SACRA depends on the accuracy of NDVI used for the CC estimation. Although SACRA shows different CC from a census-based product in some regions, multiple usages of the two products are useful to take into consideration the uncertainty of the CC. An advantage of SACRA compared to the census-based products is that SACRA provides not only planting/harvesting dates but also a peak date from the time series of NDVI data.

  10. Comparison of surface energy fluxes with satellite-derived surface energy flux estimates from a shrub-steppe

    Energy Technology Data Exchange (ETDEWEB)

    Kirkham, Randy R. [Univ. of Washington, Seattle, WA (United States)

    1993-12-01

    This thesis relates the components of the surface energy balance (i.e., net radiation, sensible and latent heat flux densities, soil heat flow) to remotely sensed data for native vegetation in a semi-arid environment. Thematic mapper data from Landsat 4 and 5 were used to estimate net radiation, sensible heat flux (H), and vegetation amount. Several sources of ground truth were employed. They included soil water balance using the neutron thermalization method and weighing lysimeters, and the measurement of energy fluxes with the Bowen ratio energy balance (BREB) technique. Sensible and latent heat flux were measured at four sites on the U.S. Department of Energy`s Hanford Site using a weighing lysimeter and/or BREB stations. The objective was to calibrate an aerodynamic transport equation that related H to radiant surface temperature. The transport equation was then used with Landsat thermal data to generate estimates of H and compare these estimates against H values obtained with BREB/lysimeters at the time of overflight. Landsat and surface meteorologic data were used to estimate the radiation budget terms at the surface. Landsat estimates of short-wave radiation reflected from the surface correlate well with reflected radiation measured using inverted Eppley pyranometers. Correlation of net radiation estimates determined from satellite data, pyranometer, air temperature, and vapor pressure compared to net radiometer values obtained at time of overflight were excellent for a single image, but decrease for multiple images. Soil heat flux, GT, is a major component of the energy balance in arid systems and G{sub T} generally decreases as vegetation cover increases. Normalized difference vegetation index (NDVI) values generated from Landsat thermatic mapper data were representative of field observations of the presence of green vegetation, but it was not possible to determine a single relationship between NDVI and GT for all sites.

  11. Estimating carbon flux phenology with satellite-derived land surface phenology and climate drivers for different biomes: a synthesis of AmeriFlux observations.

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    Wenquan Zhu

    Full Text Available Carbon Flux Phenology (CFP can affect the interannual variation in Net Ecosystem Exchange (NEE of carbon between terrestrial ecosystems and the atmosphere. In this study, we proposed a methodology to estimate CFP metrics with satellite-derived Land Surface Phenology (LSP metrics and climate drivers for 4 biomes (i.e., deciduous broadleaf forest, evergreen needleleaf forest, grasslands and croplands, using 159 site-years of NEE and climate data from 32 AmeriFlux sites and MODIS vegetation index time-series data. LSP metrics combined with optimal climate drivers can explain the variability in Start of Carbon Uptake (SCU by more than 70% and End of Carbon Uptake (ECU by more than 60%. The Root Mean Square Error (RMSE of the estimations was within 8.5 days for both SCU and ECU. The estimation performance for this methodology was primarily dependent on the optimal combination of the LSP retrieval methods, the explanatory climate drivers, the biome types, and the specific CFP metric. This methodology has a potential for allowing extrapolation of CFP metrics for biomes with a distinct and detectable seasonal cycle over large areas, based on synoptic multi-temporal optical satellite data and climate data.

  12. Estimating carbon flux phenology with satellite-derived land surface phenology and climate drivers for different biomes: a synthesis of AmeriFlux observations.

    Science.gov (United States)

    Zhu, Wenquan; Chen, Guangsheng; Jiang, Nan; Liu, Jianhong; Mou, Minjie

    2013-01-01

    Carbon Flux Phenology (CFP) can affect the interannual variation in Net Ecosystem Exchange (NEE) of carbon between terrestrial ecosystems and the atmosphere. In this study, we proposed a methodology to estimate CFP metrics with satellite-derived Land Surface Phenology (LSP) metrics and climate drivers for 4 biomes (i.e., deciduous broadleaf forest, evergreen needleleaf forest, grasslands and croplands), using 159 site-years of NEE and climate data from 32 AmeriFlux sites and MODIS vegetation index time-series data. LSP metrics combined with optimal climate drivers can explain the variability in Start of Carbon Uptake (SCU) by more than 70% and End of Carbon Uptake (ECU) by more than 60%. The Root Mean Square Error (RMSE) of the estimations was within 8.5 days for both SCU and ECU. The estimation performance for this methodology was primarily dependent on the optimal combination of the LSP retrieval methods, the explanatory climate drivers, the biome types, and the specific CFP metric. This methodology has a potential for allowing extrapolation of CFP metrics for biomes with a distinct and detectable seasonal cycle over large areas, based on synoptic multi-temporal optical satellite data and climate data.

  13. Estimating ground-level PM_{2.5} concentrations over three megalopolises in China using satellite-derived aerosol optical depth measurements

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    Zheng, Yixuan; Zhang, Qiang; Liu, Yang; Geng, Guannan; He, Kebin

    2016-04-01

    Numerous previous studies have revealed that statistical models which combine satellite-derived aerosol optical depth (AOD) and PM2.5 measurements acquired at scattered monitoring sites provide an effective method for deriving continuous spatial distributions of ground-level PM2.5 concentrations. Using the national monitoring networks that have recently been established by central and local governments in China, we developed linear mixed-effects (LMEs) models that integrate Moderate Resolution Imaging Spectroradiometer (MODIS) AOD measurements, meteorological parameters, and satellite-derived tropospheric NO2 column density measurements as predictors to estimate PM2.5 concentrations over three major industrialized regions in China, namely, the Beijing-Tianjin-Hebei region (BTH), the Yangtze River Delta region (YRD), and the Pearl River Delta region (PRD). The models developed for these three regions exploited different predictors to account for their varying topographies and meteorological conditions. Considering the importance of unbiased PM2.5 predictions for epidemiological studies, the correction factors calculated from the surface PM2.5 measurements were applied to correct biases in the predicted annual average PM2.5 concentrations introduced by non-stochastic missing AOD measurements. Leave-one-out cross-validation (LOOCV) was used to quantify the accuracy of our models. Cross-validation of the daily predictions yielded R2 values of 0.77, 0.8 and 0.8 and normalized mean error (NME) values of 22.4%, 17.8% and 15.2% for BTH, YRD and PRD, respectively. For the annual average PM2.5 concentrations, the LOOCV R2 values were 0.85, 0.76 and 0.71 for the three regions, respectively, whereas the LOOCV NME values were 8.0%, 6.9% and 8.4%, respectively. We found that the incorporation of satellite-based NO2 column density into the LMEs model contribute to considerable improvements in annual prediction accuracy for both BTH and YRD. The satisfactory performance of our

  14. Satellite-derived estimates of forest leaf area index in southwest Western Australia are not tightly coupled to interannual variations in rainfall: implications for groundwater decline in a drying climate.

    Science.gov (United States)

    Smettem, Keith R J; Waring, Richard H; Callow, John N; Wilson, Melissa; Mu, Qiaozhen

    2013-08-01

    There is increasing concern that widespread forest decline could occur in regions of the world where droughts are predicted to increase in frequency and severity as a result of climate change. The average annual leaf area index (LAI) is an indicator of canopy cover and the difference between the annual maximum and minimum LAI is an indicator of annual leaf turnover. In this study, we analyzed satellite-derived estimates of monthly LAI across forested coastal catchments of southwest Western Australia over a 12 year period (2000-2011) that included the driest year on record for the last 60 years. We observed that over the 12 year study period, the spatial pattern of average annual satellite-derived LAI values was linearly related to mean annual rainfall. However, interannual changes to LAI in response to changes in annual rainfall were far less than expected from the long-term LAI-rainfall trend. This buffered response was investigated using a physiological growth model and attributed to availability of deep soil moisture and/or groundwater storage. The maintenance of high LAIs may be linked to a long-term decline in areal average underground water storage and diminished summer flows, with an emerging trend toward more ephemeral flow regimes.

  15. Assessing the Sensitivity of Satellite-Derived Estimates of Ice Sheet Mass Balance to Regional Climate Model Simulations of Snow Accumulation and Firn Compaction

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    Briggs, K.; Shepherd, A.; Horwath, M.; Horvath, A.; Nagler, T.; Wuite, J.; Muir, A.; Gilbert, L.; Mouginot, J.

    2015-12-01

    Surface mass balance (SMB) estimates from Regional Climate Models (RCMs) are fundamental for assessing and understanding ice sheet mass trends. Mass budget and altimetry assessments rely on RCMs both directly for estimates of the SMB contribution to the total mass trend, and indirectly for ancillary data in the form of firn compaction corrections. As such, mass balance assessments can be highly sensitive to RCM outputs and therefore their accuracy. Here we assess the extent to which geodetic measurements of mass balance are sensitive to RCM model outputs at different resolutions. We achieve this by comparing SMB dependent estimates of mass balance from the mass budget method and altimetry, with those from satellite gravimetry that are independent of SMB estimates. Using the outputs of the RACMO/ANT 2.3 model at 5.5 km and 27 km horizontal spatial resolution, we generate estimates of mass balance using the mass budget method and altimetry for the Western Palmer Land region of the Antarctic Peninsula between 2003 and 2014. We find a 19% increase in the long-term (1980 to 2014) mean annual SMB for the region when enhancing the model resolution to 5.5 km. This translates into an approximate 50% reduction in the total mass loss from 2003 to 2014 calculated with the mass budget method and a 15% increase in the altimetry estimate. The use of the enhanced resolution product leads to consistency between the estimates of mass loss from the altimetry and the mass budget method that is not observed with the coarser resolution product, in which estimates of cumulative mass fall beyond the relative errors. Critically, when using the 5.5 km product, we find excellent agreement, both in pattern and magnitude, with the independent estimate derived from gravimetry. Our results point toward the crucial need for high resolution SMB products from RCMs for mass balance assessments, particularly in regions of high mass turnover and complex terrain as found over the Antarctic Peninsula.

  16. Real-Time Estimation of Satellite-Derived PM2.5 Based on a Semi-Physical Geographically Weighted Regression Model

    Science.gov (United States)

    Zhang, Tianhao; Liu, Gang; Zhu, Zhongmin; Gong, Wei; Ji, Yuxi; Huang, Yusi

    2016-01-01

    The real-time estimation of ambient particulate matter with diameter no greater than 2.5 μm (PM2.5) is currently quite limited in China. A semi-physical geographically weighted regression (GWR) model was adopted to estimate PM2.5 mass concentrations at national scale using the Aqua Moderate Resolution Imaging Spectroradiometer (MODIS) Aerosol Optical Depth product fused by the Dark Target (DT) and Deep Blue (DB) algorithms, combined with meteorological parameters. The fitting results could explain over 80% of the variability in the corresponding PM2.5 mass concentrations, and the estimation tends to overestimate when measurement is low and tends to underestimate when measurement is high. Based on World Health Organization standards, results indicate that most regions in China suffered severe PM2.5 pollution during winter. Seasonal average mass concentrations of PM2.5 predicted by the model indicate that residential regions, namely Jing-Jin-Ji Region and Central China, were faced with challenge from fine particles. Moreover, estimation deviation caused primarily by the spatially uneven distribution of monitoring sites and the changes of elevation in a relatively small region has been discussed. In summary, real-time PM2.5 was estimated effectively by the satellite-based semi-physical GWR model, and the results could provide reasonable references for assessing health impacts and offer guidance on air quality management in China. PMID:27706054

  17. Temporal disaggregation of satellite-derived monthly precipitation estimates and the resulting propagation of error in partitioning of water at the land surface

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    S.A. Margulis

    2001-01-01

    Full Text Available Global estimates of precipitation can now be made using data from a combination of geosynchronous and low earth-orbit satellites. However, revisit patterns of polar-orbiting satellites and the need to sample mixed-clouds scenes from geosynchronous satellites leads to the coarsening of the temporal resolution to the monthly scale. There are prohibitive limitations to the applicability of monthly-scale aggregated precipitation estimates in many hydrological applications. The nonlinear and threshold dependencies of surface hydrological processes on precipitation may cause the hydrological response of the surface to vary considerably based on the intermittent temporal structure of the forcing. Therefore, to make the monthly satellite data useful for hydrological applications (i.e. water balance studies, rainfall-runoff modelling, etc., it is necessary to disaggregate the monthly precipitation estimates into shorter time intervals so that they may be used in surface hydrology models. In this study, two simple statistical disaggregation schemes are developed for use with monthly precipitation estimates provided by satellites. The two techniques are shown to perform relatively well in introducing a reasonable temporal structure into the disaggregated time series. An ensemble of disaggregated realisations was routed through two land surface models of varying complexity so that the error propagation that takes place over the course of the month could be characterised. Results suggest that one of the proposed disaggregation schemes can be used in hydrological applications without introducing significant error. Keywords: precipitation, temporal disaggregation, hydrological modelling, error propagation

  18. Comparison of Satellite-Derived TOA Shortwave Clear-Sky Fluxes to Estimates from GCM Simulations Constrained by Satellite Observations of Land Surface Characteristics

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    Anantharaj, Valentine G.; Nair, Udaysankar S.; Lawrence, Peter; Chase, Thomas N.; Christopher, Sundar; Jones, Thomas

    2010-01-01

    Clear-sky, upwelling shortwave flux at the top of the atmosphere (S(sub TOA raised arrow)), simulated using the atmospheric and land model components of the Community Climate System Model 3 (CCSM3), is compared to corresponding observational estimates from the Clouds and Earth's Radiant Energy System (CERES) sensor. Improvements resulting from the use of land surface albedo derived from Moderate Resolution Imaging Spectroradiometer (MODIS) to constrain the simulations are also examined. Compared to CERES observations, CCSM3 overestimates global, annual averaged S(sub TOA raised arrow) over both land and oceans. However, regionally, CCSM3 overestimates S(sub TOA raised arrow) over some land and ocean areas while underestimating it over other sites. CCSM3 underestimates S(sub TOA raised arrow) over the Saharan and Arabian Deserts and substantial differences exist between CERES observations and CCSM3 over agricultural areas. Over selected sites, after using groundbased observations to remove systematic biases that exist in CCSM computation of S(sub TOA raised arrow), it is found that use of MODIS albedo improves the simulation of S(sub TOA raised arrow). Inability of coarse resolution CCSM3 simulation to resolve spatial heterogeneity of snowfall over high altitude sites such as the Tibetan Plateau causes overestimation of S(sub TOA raised arrow) in these areas. Discrepancies also exist in the simulation of S(sub TOA raised arrow) over ocean areas as CCSM3 does not account for the effect of wind speed on ocean surface albedo. This study shows that the radiative energy budget at the TOA is improved through the use of MODIS albedo in Global Climate Models.

  19. Satellite-derived methane emissions from inundation in Bangladesh

    Science.gov (United States)

    Peters, C. N.; Bennartz, R.; Hornberger, G. M.

    2017-05-01

    The uncertainty in methane (CH4) source strength of rice fields and wetlands is particularly high in South Asia CH4 budgets. We used satellite observations of CH4 column mixing ratios from Atmospheric Infrared Sounder (AIRS), Scanning Imaging Absorption Spectrometer for Atmospheric Chartography (SCIAMACHY), and Greenhouse Gases Observing Satellite (GOSAT) to estimate the contribution of Bangladesh emissions to atmospheric CH4 concentrations. Using satellite-derived inundation area as a proxy for source area, we developed a simple inverse advection model that estimates average annual CH4 surface fluxes to be 4, 9, and 19 mg CH4 m-2 h-1 in AIRS, SCIAMACHY, and GOSAT, respectively. Despite this variability, our flux estimates varied over a significantly narrower range than reported values for CH4 surface fluxes from a survey of 32 studies reporting ground-based observations between 0 and 260 mg CH4 m-2 h-1. Upscaling our satellite-derived surface flux estimates, we estimated total annual CH4 emissions for Bangladesh to be 1.3 ± 3.2, 1.8 ± 2.0, 3.1 ± 1.6 Tg yr-1, depending on the satellite. Our estimates of total emissions are in line with the median of total emission values for Bangladesh reported in earlier studies.

  20. Ganga-Brahmaputra river discharge from Jason-2 radar altimetry: An update to the long-term satellite-derived estimates of continental freshwater forcing flux into the Bay of Bengal

    Digital Repository Service at National Institute of Oceanography (India)

    Papa, F.; Bala, S.K.; Pandey, R.K.; Durand, F.; Gopalakrishna, V.V.; Rahman, A.; Rossow, W.B.

    large sample of in situ river height measurements, we estimate the standard error of Jason-2-derived water levels over the Ganga and the Brahmaputra to be respectively of 0.28 m and 0.19 m, or less than approx 4 percent of the annual peak...

  1. Can a Satellite-Derived Estimate of the Fraction of PAR Absorbed by Chlorophyll (FAPAR(sub chl)) Improve Predictions of Light-Use Efficiency and Ecosystem Photosynthesis for a Boreal Aspen Forest?

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    Zhang, Qingyuan; Middleton, Elizabeth M.; Margolis, Hank A.; Drolet, Guillaume G.; Barr, Alan A.; Black, T. Andrew

    2009-01-01

    Gross primary production (GPP) is a key terrestrial ecophysiological process that links atmospheric composition and vegetation processes. Study of GPP is important to global carbon cycles and global warming. One of the most important of these processes, plant photosynthesis, requires solar radiation in the 0.4-0.7 micron range (also known as photosynthetically active radiation or PAR), water, carbon dioxide (CO2), and nutrients. A vegetation canopy is composed primarily of photosynthetically active vegetation (PAV) and non-photosynthetic vegetation (NPV; e.g., senescent foliage, branches and stems). A green leaf is composed of chlorophyll and various proportions of nonphotosynthetic components (e.g., other pigments in the leaf, primary/secondary/tertiary veins, and cell walls). The fraction of PAR absorbed by whole vegetation canopy (FAPAR(sub canopy)) has been widely used in satellite-based Production Efficiency Models to estimate GPP (as a product of FAPAR(sub canopy)x PAR x LUE(sub canopy), where LUE(sub canopy) is light use efficiency at canopy level). However, only the PAR absorbed by chlorophyll (a product of FAPAR(sub chl) x PAR) is used for photosynthesis. Therefore, remote sensing driven biogeochemical models that use FAPAR(sub chl) in estimating GPP (as a product of FAPAR(sub chl x PAR x LUE(sub chl) are more likely to be consistent with plant photosynthesis processes.

  2. Initialization with diabatic heating from satellite-derived rainfall

    Science.gov (United States)

    Ma, Leiming; Chan, Johnny; Davidson, Noel E.; Turk, Joe

    2007-07-01

    In this paper, a new technique is proposed to improve initialization of a tropical cyclone (TC) prediction model using diabatic heating profiles estimated from a combination of both infrared satellite cloud imagery and satellite-derived rainfall. The method is termed Rainfall-defined Diabatic Heating, RDH. To examine the RDH performance, initialization and forecast experiments are made with the Australia Bureau of Meteorology Research Centre (BMRC) Tropical Cyclone — Limited Area Prediction System (TC-LAPS) for the case of TC Chris, which made landfall on the west coast of Australia during 3-6 Feb 2002. RDH is performed in three steps: 1) based on previous observational and numerical studies, reference diabatic heating profiles are firstly classified into three kinds: convective, stratiform or composite types; 2) NRL (Naval Research Laboratory) 3-hourly gridded satellite rainfall estimates are categorized as one of the three types according to the rain rate; 3) within a nudging phase of 24 h, the model-generated heating at each grid point during the integration is replaced by the reference heating profiles on the basis of the satellite-observed cloud top temperature and rainfall type. The results of sensitivity experiments show that RDH has a positive impact on the model initialization of TC Chris. The heating profiles generated by the model within the observed rainfall area show agreement with that of reference heating. That is, maximum heating is located in the lower troposphere for convective rainfall, and in the upper troposphere for stratiform rainfall. In response to the replaced heating and its impact on the TC structure, the model initial condition and forecasts of the track and intensity are improved.

  3. New estimate for the time-dependent thermal nucleosynthesis of $^{180}$Ta$^m$

    CERN Document Server

    Hayakawa, T; Chiba, S; Mathews, G J; 10.1103/PhysRevC.81.052801

    2010-01-01

    We have made a new time-dependent calculation of the supernova production ratio of the long-lived isomeric state of $^{180}$Ta. Such a time-dependent solution is crucial for understanding the production and survival of this isotope. We include the explicit linking between the isomer and all known excited states.We have also calculated the properties of possible links to a conjectured excited state that might decrease the final isomer residual ratio. We find that the explicit time evolution of the synthesis of $^{180}$Ta using the available nuclear data avoids the overproduction relative to $^{138}$La for a $\

  4. Migratory herbivorous waterfowl track satellite-derived green wave index.

    Science.gov (United States)

    Shariatinajafabadi, Mitra; Wang, Tiejun; Skidmore, Andrew K; Toxopeus, Albertus G; Kölzsch, Andrea; Nolet, Bart A; Exo, Klaus-Michael; Griffin, Larry; Stahl, Julia; Cabot, David

    2014-01-01

    Many migrating herbivores rely on plant biomass to fuel their life cycles and have adapted to following changes in plant quality through time. The green wave hypothesis predicts that herbivorous waterfowl will follow the wave of food availability and quality during their spring migration. However, testing this hypothesis is hampered by the large geographical range these birds cover. The satellite-derived normalized difference vegetation index (NDVI) time series is an ideal proxy indicator for the development of plant biomass and quality across a broad spatial area. A derived index, the green wave index (GWI), has been successfully used to link altitudinal and latitudinal migration of mammals to spatio-temporal variations in food quality and quantity. To date, this index has not been used to test the green wave hypothesis for individual avian herbivores. Here, we use the satellite-derived GWI to examine the green wave hypothesis with respect to GPS-tracked individual barnacle geese from three flyway populations (Russian n = 12, Svalbard n = 8, and Greenland n = 7). Data were collected over three years (2008-2010). Our results showed that the Russian and Svalbard barnacle geese followed the middle stage of the green wave (GWI 40-60%), while the Greenland geese followed an earlier stage (GWI 20-40%). Despite these differences among geese populations, the phase of vegetation greenness encountered by the GPS-tracked geese was close to the 50% GWI (i.e. the assumed date of peak nitrogen concentration), thereby implying that barnacle geese track high quality food during their spring migration. To our knowledge, this is the first time that the migration of individual avian herbivores has been successfully studied with respect to vegetation phenology using the satellite-derived GWI. Our results offer further support for the green wave hypothesis applying to long-distance migrants on a larger scale.

  5. Migratory herbivorous waterfowl track satellite-derived green wave index.

    Directory of Open Access Journals (Sweden)

    Mitra Shariatinajafabadi

    Full Text Available Many migrating herbivores rely on plant biomass to fuel their life cycles and have adapted to following changes in plant quality through time. The green wave hypothesis predicts that herbivorous waterfowl will follow the wave of food availability and quality during their spring migration. However, testing this hypothesis is hampered by the large geographical range these birds cover. The satellite-derived normalized difference vegetation index (NDVI time series is an ideal proxy indicator for the development of plant biomass and quality across a broad spatial area. A derived index, the green wave index (GWI, has been successfully used to link altitudinal and latitudinal migration of mammals to spatio-temporal variations in food quality and quantity. To date, this index has not been used to test the green wave hypothesis for individual avian herbivores. Here, we use the satellite-derived GWI to examine the green wave hypothesis with respect to GPS-tracked individual barnacle geese from three flyway populations (Russian n = 12, Svalbard n = 8, and Greenland n = 7. Data were collected over three years (2008-2010. Our results showed that the Russian and Svalbard barnacle geese followed the middle stage of the green wave (GWI 40-60%, while the Greenland geese followed an earlier stage (GWI 20-40%. Despite these differences among geese populations, the phase of vegetation greenness encountered by the GPS-tracked geese was close to the 50% GWI (i.e. the assumed date of peak nitrogen concentration, thereby implying that barnacle geese track high quality food during their spring migration. To our knowledge, this is the first time that the migration of individual avian herbivores has been successfully studied with respect to vegetation phenology using the satellite-derived GWI. Our results offer further support for the green wave hypothesis applying to long-distance migrants on a larger scale.

  6. Satellite-derived sea surface height and sea surface wind data fusion for spilled oil tracking

    Science.gov (United States)

    Kozai, Katsutoshi

    2003-12-01

    An attempt is made to estimate the trajectory of the spilled oil from the sunken tanker Nakhodka occurred on January 2, 1997 in the Japan Sea by fusing two microwave sensor data, namely ERS-2 altimeter and ADEOS/NSCAT scatterometer data. In this study 'fusion' is defined as the method of more reliable prediction for the trajectory of spilled oil than before. Geostrophic current vectors are derived from ERS-2 altimeter and wind-induced drift vectors are derived from ADEOS/NSCAT scatterometer data These two different satellite-derived vectors are 'fused' together in the surface current model to estimate and evaluate the trajectory of spilled oil from the sunken tanker Nakhodka. The distribution of component of spill vector is mostly accounted for by the distribution of geostrophic velocity component during the study period with some discrepancies during March, 1997.

  7. Temporal Trends in Satellite-Derived Erythemal UVB and Implications for Ambient Sun Exposure Assessment

    Directory of Open Access Journals (Sweden)

    Marvin Langston

    2017-02-01

    Full Text Available Ultraviolet radiation (UVR has been associated with various health outcomes, including skin cancers, vitamin D insufficiency, and multiple sclerosis. Measurement of UVR has been difficult, traditionally relying on subject recall. We investigated trends in satellite-derived UVB from 1978 to 2014 within the continental United States (US to inform UVR exposure assessment and determine the potential magnitude of misclassification bias created by ignoring these trends. Monthly UVB data remotely sensed from various NASA satellites were used to investigate changes over time in the United States using linear regression with a harmonic function. Linear regression models for local geographic areas were used to make inferences across the entire study area using a global field significance test. Temporal trends were investigated across all years and separately for each satellite type due to documented differences in UVB estimation. UVB increased from 1978 to 2014 in 48% of local tests. The largest UVB increase was found in Western Nevada (0.145 kJ/m2 per five-year increment, a total 30-year increase of 0.87 kJ/m2. This largest change only represented 17% of total ambient exposure for an average January and 2% of an average July in Western Nevada. The observed trends represent cumulative UVB changes of less than a month, which are not relevant when attempting to estimate human exposure. The observation of small trends should be interpreted with caution due to measurement of satellite parameter inputs (ozone and climatological factors that may impact derived satellite UVR nearly 20% compared to ground level sources. If the observed trends hold, satellite-derived UVB data may reasonably estimate ambient UVB exposures even for outcomes with long latency phases that predate the satellite record.

  8. Online Assessment of Satellite-Derived Global Precipitation Products

    Science.gov (United States)

    Liu, Zhong; Ostrenga, D.; Teng, W.; Kempler, S.

    2012-01-01

    Precipitation is difficult to measure and predict. Each year droughts and floods cause severe property damages and human casualties around the world. Accurate measurement and forecast are important for mitigation and preparedness efforts. Significant progress has been made over the past decade in satellite precipitation product development. In particular, products' spatial and temporal resolutions as well as timely availability have been improved by blended techniques. Their resulting products are widely used in various research and applications. However biases and uncertainties are common among precipitation products and an obstacle exists in quickly gaining knowledge of product quality, biases and behavior at a local or regional scale, namely user defined areas or points of interest. Current online inter-comparison and validation services have not addressed this issue adequately. To address this issue, we have developed a prototype to inter-compare satellite derived daily products in the TRMM Online Visualization and Analysis System (TOVAS). Despite its limited functionality and datasets, users can use this tool to generate customized plots within the United States for 2005. In addition, users can download customized data for further analysis, e.g. comparing their gauge data. To meet increasing demands, we plan to increase the temporal coverage and expanded the spatial coverage from the United States to the globe. More products have been added as well. In this poster, we present two new tools: Inter-comparison of 3B42RT and 3B42 Inter-comparison of V6 and V7 TRMM L-3 monthly products The future plans include integrating IPWG (International Precipitation Working Group) Validation Algorithms/statistics, allowing users to generate customized plots and data. In addition, we will expand the current daily products to monthly and their climatology products. Whenever the TRMM science team changes their product version number, users would like to know the differences by

  9. Spatial disaggregation of satellite-derived irradiance using a high-resolution digital elevation model

    Energy Technology Data Exchange (ETDEWEB)

    Ruiz-Arias, Jose A.; Tovar-Pescador, Joaquin [Department of Physics, University of Jaen (Spain); Cebecauer, Tomas [European Commission, Joint Research Centre, Ispra (Italy); GeoModel s.r.o., Bratislava (Slovakia); Institute of Geography, Slovak Academy of Sciences, Bratislava (Slovakia); Suri, Marcel [European Commission, Joint Research Centre, Ispra (Italy); GeoModel s.r.o., Bratislava (Slovakia)

    2010-09-15

    Downscaling of the Meteosat-derived solar radiation ({proportional_to}5 km grid resolution) is based on decomposing the global irradiance and correcting the systematic bias of its components using the elevation and horizon shadowing that are derived from the SRTM-3 digital elevation model (3 arc sec resolution). The procedure first applies the elevation correction based on the difference between coarse and high spatial resolution. Global irradiance is split into direct, diffuse circumsolar and diffuse isotropic components using statistical models, and then corrections due to terrain shading and sky-view fraction are applied. The effect of reflected irradiance is analysed only in the theoretical section. The method was applied in the eastern Andalusia, Spain, and the validation was carried out for 22 days on April, July and December 2006 comparing 15-min estimates of the satellite-derived solar irradiance and observations from nine ground stations. Overall, the corrections of the satellite estimates in the studied region strongly reduced the mean bias of the estimates for clear and cloudy days from roughly 2.3% to 0.4%. (author)

  10. Analysis of satellite-derived Arctic tropospheric BrO columns in conjunction with aircraft measurements during ARCTAS and ARCPAC

    Directory of Open Access Journals (Sweden)

    S. Choi

    2011-09-01

    Full Text Available We derive estimates of tropospheric BrO column amounts during two Arctic field campaigns in 2008 using information from the satellite UV nadir sensors Ozone Monitoring Instrument (OMI and the second Global Ozone Monitoring Experiment (GOME-2 as well as estimates of stratospheric BrO columns from a model simulation. The sensitivity of the satellite-derived tropospheric BrO columns to various parameters is investigated using a radiative transfer model. We conduct a comprehensive analysis of satellite-derived tropospheric BrO columns including a detailed comparison with aircraft in-situ observations of BrO and related species obtained during the field campaigns. In contrast to prior expectation, tropospheric BrO, when present, existed over a broad range of altitudes. Our results show reasonable agreement between tropospheric BrO columns derived from the satellite observations and columns found using aircraft in-situ BrO. After accounting for the stratospheric contribution to total BrO column, several events of rapid BrO activation due to surface processes in the Arctic are apparent in both the OMI and GOME-2 based tropospheric columns. The wide orbital swath of OMI allows examination of the evolution of tropospheric BrO on about hourly time intervals near the pole. Low pressure systems, strong surface winds, and high planetary boundary layer heights are associated with the observed tropospheric BrO activation events.

  11. High resolution satellite derived erodibility factors for WRF/Chem windblown dust simulations in Argentina

    Science.gov (United States)

    Cremades, Pablo Gabriel; Fernandez, Rafael Pedro; Allend, David; Mulena, Celeste; Puliafito, Salvador Enrique

    2017-04-01

    A proper representation of dust sources is critical to accurately predict atmospheric particle concentrations in regional windblown dust simulations. The Weather Research and Forecasting model with Chemistry (WRF/Chem) includes a topographic-based erodibility map originally conceived for global scale modeling, which fails to identify the geographical location of dust sources in many regions of Argentina. Therefore, this study aims at developing a method to obtain a high-resolution erodibility map suitable for regional or local scale modeling using WRF/Chem. We present two independent approaches based on global methods to estimate soil erodibility using satellite retrievals, i.e. topography from the Shuttle Radar Topography Mission (SRTM) and surface reflectance from the Moderate Resolution Imaging Spectroradiometer (MODIS). Simulation results of a severe Zonda wind episode in the arid central-west Argentina serve as bases for the analysis of these methods. Simulated dust concentration at surface level is compared with particulate matter measurements at one site in Mendoza city. In addition, we use satellite aerosol optical depth (AOD) retrievals to investigate model performance in reproducing spatial distribution of dust emissions. The erodibility map based on surface reflectance from MODIS improves the representation of small scale features, and increases the overall dust aerosol loading with respect to the standard map included by default. Simulated concentrations are in good agreement with measurements as well as satellite derived dust spatial distribution.

  12. Poverty, health and satellite-derived vegetation indices: their inter-spatial relationship in West Africa.

    Science.gov (United States)

    Sedda, Luigi; Tatem, Andrew J; Morley, David W; Atkinson, Peter M; Wardrop, Nicola A; Pezzulo, Carla; Sorichetta, Alessandro; Kuleszo, Joanna; Rogers, David J

    2015-03-01

    Previous analyses have shown the individual correlations between poverty, health and satellite-derived vegetation indices such as the normalized difference vegetation index (NDVI). However, generally these analyses did not explore the statistical interconnections between poverty, health outcomes and NDVI. In this research aspatial methods (principal component analysis) and spatial models (variography, factorial kriging and cokriging) were applied to investigate the correlations and spatial relationships between intensity of poverty, health (expressed as child mortality and undernutrition), and NDVI for a large area of West Africa. This research showed that the intensity of poverty (and hence child mortality and nutrition) varies inversely with NDVI. From the spatial point-of-view, similarities in the spatial variation of intensity of poverty and NDVI were found. These results highlight the utility of satellite-based metrics for poverty models including health and ecological components and, in general for large scale analysis, estimation and optimisation of multidimensional poverty metrics. However, it also stresses the need for further studies on the causes of the association between NDVI, health and poverty. Once these relationships are confirmed and better understood, the presence of this ecological component in poverty metrics has the potential to facilitate the analysis of the impacts of climate change on the rural populations afflicted by poverty and child mortality. © The Author 2015. Published by Oxford University Press on behalf of Royal Society of Tropical Medicine and Hygiene. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  13. Adequacy of satellite derived rainfall data for stream flow modeling

    Science.gov (United States)

    Artan, G.; Gadain, Hussein; Smith, Jody L.; Asante, Kwasi; Bandaragoda, C.J.; Verdin, J.P.

    2007-01-01

    Floods are the most common and widespread climate-related hazard on Earth. Flood forecasting can reduce the death toll associated with floods. Satellites offer effective and economical means for calculating areal rainfall estimates in sparsely gauged regions. However, satellite-based rainfall estimates have had limited use in flood forecasting and hydrologic stream flow modeling because the rainfall estimates were considered to be unreliable. In this study we present the calibration and validation results from a spatially distributed hydrologic model driven by daily satellite-based estimates of rainfall for sub-basins of the Nile and Mekong Rivers. The results demonstrate the usefulness of remotely sensed precipitation data for hydrologic modeling when the hydrologic model is calibrated with such data. However, the remotely sensed rainfall estimates cannot be used confidently with hydrologic models that are calibrated with rain gauge measured rainfall, unless the model is recalibrated. ?? Springer Science+Business Media, Inc. 2007.

  14. Incorporating Uncertainties in Satellite-Derived Chlorophyll into Model Forecasts

    Science.gov (United States)

    2012-10-01

    radiances in the seven visible MODIS channels used in the estimation of the bio-optical products, such as chlorophyll, absorption and backscattering...grazers, nitrate, silicate, ammonium, and two detritus pools. Phytoplankton photosynthesis in the biochemical model is driven by Photosynthetically

  15. Using GIS data and satellite derived irradiance to optimize siting of PV installations in Switzerland

    Science.gov (United States)

    Kahl, Annelen; Nguyen, Viet-Anh; Bartlett, Stuart; Sossan, Fabrizio; Lehning, Michael

    2016-04-01

    For a successful distribution strategy of PV installations, it does not suffice to choose the locations with highest annual total irradiance. Attention needs to be given to spatial correlation patterns of insolation to avoid large system-wide variations, which can cause extended deficits in supply or might even damage the electrical network. One alternative goal instead is to seek configurations that provide the smoothest energy production, with the most reliable and predictable supply. Our work investigates several scenarios, each pursuing a different strategy for a future renewable Switzerland without nuclear power. Based on an estimate for necessary installed capacity for solar power [Bartlett, 2015] we first use heuristics to pre-select realistic placements for PV installations. Then we apply optimization methods to find a subset of locations that provides the best possible combined electricity production. For the first part of the selection process, we use a DEM to exclude high elevation zones which would be difficult to access and which are prone to natural hazards. Then we use land surface cover information to find all zones with potential roof area, deemed suitable for installation of solar panels. The optimization employs Principal Component Analysis of satellite derived irradiance data (Surface Incoming Shortwave Radiation (SIS), based on Meteosat Second Generation sensors) to incorporate a spatial aspect into the selection process that does not simply maximize annual total production but rather provides the most robust supply, by combining regions with anti-correlated cloud cover patterns. Depending on the initial assumptions and constraints, the resulting distribution schemes for PV installations vary with respect to required surface area, annual total and lowest short-term production, and illustrate how important it is to clearly define priorities and policies for a future renewable Switzerland.

  16. Potential of satellite-derived ecosystem functional attributes to anticipate species range shifts

    Science.gov (United States)

    Alcaraz-Segura, Domingo; Lomba, Angela; Sousa-Silva, Rita; Nieto-Lugilde, Diego; Alves, Paulo; Georges, Damien; Vicente, Joana R.; Honrado, João P.

    2017-05-01

    In a world facing rapid environmental changes, anticipating their impacts on biodiversity is of utmost relevance. Remotely-sensed Ecosystem Functional Attributes (EFAs) are promising predictors for Species Distribution Models (SDMs) by offering an early and integrative response of vegetation performance to environmental drivers. Species of high conservation concern would benefit the most from a better ability to anticipate changes in habitat suitability. Here we illustrate how yearly projections from SDMs based on EFAs could reveal short-term changes in potential habitat suitability, anticipating mid-term shifts predicted by climate-change-scenario models. We fitted two sets of SDMs for 41 plant species of conservation concern in the Iberian Peninsula: one calibrated with climate variables for baseline conditions and projected under two climate-change-scenarios (future conditions); and the other calibrated with EFAs for 2001 and projected annually from 2001 to 2013. Range shifts predicted by climate-based models for future conditions were compared to the 2001-2013 trends from EFAs-based models. Projections of EFAs-based models estimated changes (mostly contractions) in habitat suitability that anticipated, for the majority (up to 64%) of species, the mid-term shifts projected by traditional climate-change-scenario forecasting, and showed greater agreement with the business-as-usual scenario than with the sustainable-development one. This study shows how satellite-derived EFAs can be used as meaningful essential biodiversity variables in SDMs to provide early-warnings of range shifts and predictions of short-term fluctuations in suitable conditions for multiple species.

  17. Utilizing Satellite-derived Precipitation Products in Hydrometeorological Applications

    Science.gov (United States)

    Liu, Z.; Ostrenga, D.; Teng, W. L.; Kempler, S. J.; Huffman, G. J.

    2012-12-01

    Each year droughts and floods happen around the world and can cause severe property damages and human casualties. Accurate measurement and forecast are important for preparedness and mitigation efforts. Through multi-satellite blended techniques, significant progress has been made over the past decade in satellite-based precipitation product development, such as, products' spatial and temporal resolutions as well as timely availability. These new products are widely used in various research and applications. In particular, the TRMM Multi-satellite Precipitation Analysis (TMPA) products archived and distributed by the NASA Goddard Earth Sciences (GES) Data and Information Services Center (DISC) provide 3-hourly, daily and monthly near-global (50° N - 50° S) precipitation datasets for research and applications. Two versions of TMPA products are available, research (3B42, 3B43, rain gauge adjusted) and near-real-time (3B42RT). At GES DISC, we have developed precipitation data services to support hydrometeorological applications in order to maximize the TRMM mission's societal benefits. In this presentation, we will present examples of utilizing TMPA precipitation products in hydrometeorological applications including: 1) monitoring global floods and droughts; 2) providing data services to support the USDA Crop Explorer; 3) support hurricane monitoring activities and research; and 4) retrospective analog year analyses to improve USDA's world agricultural supply and demand estimates. We will also present precipitation data services that can be used to support hydrometeorological applications including: 1) User friendly TRMM Online Visualization and Analysis System (TOVAS; URL: http://disc2.nascom.nasa.gov/Giovanni/tovas/); 2) Mirador (http://mirador.gsfc.nasa.gov/), a simplified interface for searching, browsing, and ordering Earth science data at GES DISC; 3) Simple Subset Wizard (http://disc.sci.gsfc.nasa.gov/SSW/ ) for data subsetting and format conversion; 4) Data

  18. Comparison and evaluation of satellite derived precipitation products for hydrological modeling of the Zambezi River Basin

    Directory of Open Access Journals (Sweden)

    T. Cohen Liechti

    2011-08-01

    Full Text Available In the framework of the African Dams ProjecT (ADAPT, an integrated water resource management study in the Zambezi Basin is currently under development. In view of the sparse gauging network for rainfall monitoring, the observations from spaceborne instrumentation currently produce the only available rainfall data for a large part of the basin.

    Three operational and acknowledged high resolution satellite derived estimates: the Tropical Rainfall Measuring Mission product 3B42 (TRMM 3B42, the Famine Early Warning System product 2.0 (FEWS RFE2.0 and the National Oceanic and Atmospheric Administration/Climate Prediction Centre (NOAA/CPC morphing technique (CMORPH are analyzed in terms of spatial and temporal repartition of the precipitations. They are compared to ground data for the wet seasons of the years 2003 to 2009 on a point to pixel basis at daily, 10-daily and monthly time steps and on a pixel to pixel basis for the wet seasons of the years 2003 to 2007 at monthly time steps.

    The general North-South gradient of precipitation is captured by all the analyzed products. Regarding the spatial heterogeneity, FEWS pixels are much more inter-correlated than TRMM and CMORPH pixels. For a rainfall homogeneity threshold criterion of 0.5 global mean correlation coefficient, the area of each subbasin should not exceed a circle of 2.5° latitude/longitude radius for FEWS and a circle of 0.75° latitude/longitude radius for TRMM and CMORPH considering rectangular mesh.

    In terms of reliability, the correspondence of all estimates with ground data increases with the time step chosen for the analysis. The volume ratio computation indicates that CMORPH is overestimating by nearly 1.5 times the rainfall. The statistics of TRMM and FEWS estimates show quite similar results.

    Due to the its lower inter-correlation and longer data set, the TRMM 3B42 product is chosen as input for the hydraulic-hydrologic model of the basin.

  19. Magnetic property and interface structure of Ta/NiO/NiFe/Ta

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Ta/NiO/NiFe/Ta multilayers, utilizing Ta as buffer layer, were prepared by rf reactive and dc magnetron sputtering. The exchange coupling field between NiO and NiFe reached a maximum value of 9.6×103 A/m at a NiO film thickness of 50 nm. The composition and chemical states at interface region of Ta/NiO/Ta were studied by using the X-ray photoelectron spectroscopy (XPS) and peak decomp- osition technique. The results show that there is an "inter- mixing layer" at the Ta/NiO (and NiO/Ta) interface due to a thermodynamically favorable reaction 2Ta + 5NiO = 5Ni + Ta2O5. This interface reaction has a great effect on exchange coupling. The thickness of Ni+NiO estimated by XPS depth- profiles is about 8-10 nm.

  20. Calibration of the Distributed Hydrological Model mHM using Satellite derived Land Surface Temperature

    Science.gov (United States)

    Zink, M.; Samaniego, L. E.; Cuntz, M.

    2012-12-01

    A combined investigation of the water and energy balance in hydrologic models can lead to a more accurate estimation of hydrological fluxes and state variables, such as evapotranspiration and soil moisture. Hydrologic models are usually calibrated against discharge measurements, and thus are only trained on information of few points within a catchment. This procedure does not take into account any spatio-temporal variability of fluxes or state variables. Satellite data are a useful source of information to account for this spatial distributions. The objective of this study is to calibrate the distributed hydrological model mHM with satellite derived Land Surface Temperature (LST) fields provided by the Land Surface Analysis - Satellite Application Facility (LSA-SAF). LST is preferred to other satellite products such as soil moisture or evapotranspiration due to its higher precision. LST is obtained by solving the energy balance by assuming that the soil heat flux and the storage term are negligible on a daily time step. The evapotranspiration is determined by closing the water balance in mHM. The net radiation is calculated by using the incoming short- and longwave radiation, albedo and emissivity data provided by LSA-SAF. The Multiscale Parameter Regionalization technique (MPR, Samaniego et al. 2010) is used to determine the aerodynamic resistance among other parameters. The optimization is performed within the time period 2008-2010 using three objective functions that consider 1) only discharge, 2) only LST, and 3) a combination of both. The proposed method is applied to seven major German river basins: Danube, Ems, Main, Mulde, Neckar, Saale, and Weser. The annual coefficient of correlation between LSA-SAF incoming shortwave radiation and 28 meteorological stations operated by the German Weather Service (DWD) is 0.94 (RMSE = 29 W m-2) in 2009. LSA-SAF incoming longwave radiation could be further evaluated at two eddy covariance stations with a very similar

  1. Phase Velocity Estimation of a Microstrip Line in a Stoichiometric Periodically Domain-Inverted LiTaO3 Modulator Using Electro-Optic Sampling Technique

    Directory of Open Access Journals (Sweden)

    Shintaro Hisatake

    2008-01-01

    Full Text Available We estimate the phase velocity of a modulation microwave in a quasi-velocity-matched (QVM electro-optic (EO phase modulator (QVM-EOM using EO sampling which is accurate and the most reliable technique for measuring voltage waveforms at an electrode. The substrate of the measured QVM-EOM is a stoichiometric periodically domain-inverted LiTaO3 crystal. The electric field of a standing wave in a resonant microstrip line (width: 0.5 mm, height: 0.5 mm is measured by employing a CdTe crystal as an EO sensor. The wavelength of the traveling microwave at 16.0801 GHz is determined as 3.33 mm by fitting the theoretical curve to the measured electric field distribution. The phase velocity is estimated as vm=5.35×107 m/s, though there exists about 5% systematic error due to the perturbation by the EO sensor. Relative dielectric constant of εr=41.5 is led as the maximum likelihood value that derives the estimated phase velocity.

  2. Evaluating satellite-derived long-term historical precipitation datasets for drought monitoring in Chile

    Science.gov (United States)

    Zambrano, Francisco; Wardlow, Brian; Tadesse, Tsegaye

    2016-10-01

    Precipitation is a key parameter for the study of climate change and variability and the detection and monitoring of natural disaster such as drought. Precipitation datasets that accurately capture the amount and spatial variability of rainfall is critical for drought monitoring and a wide range of other climate applications. This is challenging in many parts of the world, which often have a limited number of weather stations and/or historical data records. Satellite-derived precipitation products offer a viable alternative with several remotely sensed precipitation datasets now available with long historical data records (+30 years), which include the Climate Hazards Group InfraRed Precipitation with Station (CHIRPS) and Precipitation Estimation from Remotely Sensed Information using Artificial Neural Networks-Climate Data Record (PERSIANN-CDR) datasets. This study presents a comparative analysis of three historical satellite-based precipitation datasets that include Tropical Rainfall Measuring Mission (TRMM) Multi-satellite Precipitation Analysis (TMPA) 3B43 version 7 (1998-2015), PERSIANN-CDR (1983-2015) and CHIRPS 2.0 (1981-2015) over Chile to assess their performance across the country and evaluate their applicability for agricultural drought evaluation when used in the calculation of commonly used drought indicator as the Standardized Precipitation Index (SPI). In this analysis, 278 weather stations of in-situ rainfall measurements across Chile were initially compared to the satellite-based precipitation estimates. The study area (Chile) was divided into five latitudinal zones: North, North-Central, Central, South-Central and South to determine if there were a regional difference among these satellite-based estimates. Nine statistics were used to evaluate the performance of satellite products to estimate the amount and spatial distribution of historical rainfall across Chile. Hierarchical cluster analysis, k-means and singular value decomposition were used to

  3. Estimation of nitrate flux in a tidal front satellite-derived temperature data

    Digital Repository Service at National Institute of Oceanography (India)

    Morin; Wafar, M.V.M.; Corre, P.L.

    stream_size 7 stream_content_type text/plain stream_name J_Geophys_Res_C_98_4689.pdf.txt stream_source_info J_Geophys_Res_C_98_4689.pdf.txt Content-Encoding ISO-8859-1 Content-Type text/plain; charset=ISO-8859-1 ...

  4. Evaluating satellite-derived long-term historical precipitation datasets for drought monitoring in Chile

    Science.gov (United States)

    Zambrano, Francisco; Wardlow, Brian; Tadesse, Tsegaye; Lillo-Saavedra, Mario; Lagos, Octavio

    2017-04-01

    Precipitation is a key parameter for the study of climate change and variability and the detection and monitoring of natural disaster such as drought. Precipitation datasets that accurately capture the amount and spatial variability of rainfall is critical for drought monitoring and a wide range of other climate applications. This is challenging in many parts of the world, which often have a limited number of weather stations and/or historical data records. Satellite-derived precipitation products offer a viable alternative with several remotely sensed precipitation datasets now available with long historical data records (+30years), which include the Climate Hazards Group InfraRed Precipitation with Station (CHIRPS) and Precipitation Estimation from Remotely Sensed Information using Artificial Neural Networks-Climate Data Record (PERSIANN-CDR) datasets. This study presents a comparative analysis of three historical satellite-based precipitation datasets that include Tropical Rainfall Measuring Mission (TRMM) Multi-satellite Precipitation Analysis (TMPA) 3B43 version 7 (1998-2015), PERSIANN-CDR (1983-2015) and CHIRPS 2.0 (1981-2015) over Chile to assess their performance across the country and for the case of the two long-term products the applicability for agricultural drought were evaluated when used in the calculation of commonly used drought indicator as the Standardized Precipitation Index (SPI). In this analysis, 278 weather stations of in situ rainfall measurements across Chile were initially compared to the satellite data. The study area (Chile) was divided into five latitudinal zones: North, North-Central, Central, South-Central and South to determine if there were a regional difference among these satellite products, and nine statistics were used to evaluate their performance to estimate the amount and spatial distribution of historical rainfall across Chile. Hierarchical cluster analysis, k-means and singular value decomposition were used to analyze

  5. a Diagnostic Approach to Obtaining Planetary Boundary Layer Winds Using Satellite-Derived Thermal Data

    Science.gov (United States)

    Belt, Carol Lynn

    The feasibility of using satellite-derived thermal data to generate realistic synoptic-scale winds within the planetary boundary layer (PBL) is examined. Diagnostic "modified Ekman" wind equations from the Air Force Global Weather Central (AFGWC) Boundary Layer Model are used to compute winds at seven levels within the PBL transition layer (50 m to 1600 m AGL). Satellite-derived winds based on 62 predawn (0921 GMT 19 April 1979) TIROS-N soundings are compared to similarly-derived wind fields based on 39 AVE-SESAME II rawinsonde (RAOB) soundings taken 2 h later. Actual wind fields are also used as a basis for comparison. Qualitative and statistical comparisons show that the Ekman winds from both sources are in very close agreement, with an average vector correlation coefficient of 0.815. Best results are obtained at 300 m AGL. Satellite winds tend to be slightly weaker than their RAOB counterparts and exhibit a greater degree of cross-isobaric flow. The modified Ekman winds show a significant improvement over geostrophic values at levels nearest the surface. Horizontal moisture divergence, moisture advection, velocity divergence and relative vorticity are computed at 300 m AGL using satellite-derived winds and moisture data. Results show excellent agreement with corresponding RAOB-derived values. Areas of horizontal moisture convergence, velocity convergence, and positive vorticity are nearly coincident and align in regions which later develop intense convection. Vertical motion at 1600 m AGL is computed using stepwise integration of the satellite winds through the PBL. Values and patterns are similar to those obtained using the RAOB-derived winds. Regions of maximum upward motion correspond with areas of greatest moisture convergence and the convection that later develops.

  6. A Satellite-Derived Upper-Tropospheric Water Vapor Transport Index for Climate Studies

    Science.gov (United States)

    Jedlovec, Gray J.; Lerner, Jeffrey A.; Atkinson, Robert J.

    1998-01-01

    A new approach is presented to quantify upper-level moisture transport from geostationary satellite data. Daily time sequences of Geostationary Operational Environmental Satellite GOES-7 water vapor imagery were used to produce estimates of winds and water vapor mixing ratio in the cloud-free region of the upper troposphere sensed by the 6.7- microns water vapor channel. The winds and mixing ratio values were gridded and then combined to produce a parameter called the water vapor transport index (WVTI), which represents the magnitude of the two-dimensional transport of water vapor in the upper troposphere. Daily grids of WVTI, meridional moisture transport, mixing ratio, pressure, and other associated parameters were averaged to produce monthly fields for June, July, and August (JJA) of 1987 and 1988 over the Americas and surrounding oceanic regions, The WVTI was used to compare upper-tropospheric moisture transport between the summers of 1987 and 1988, contrasting the latter part of the 1986/87 El Nino event and the La Nina period of 1988. A similar product derived from the National Centers for Environmental Prediction (NCEP)-National Center for Atmospheric Research (NCAR) 40-Year Reanalysis Project was used to help to validate the index. Although the goal of this research was to describe the formulation and utility of the WVTI, considerable insight was obtained into the interannual variability of upper-level water vapor transport. Both datasets showed large upper-level water vapor transport associated with synoptic features over the Americas and with outflow from tropical convective systems. Minimal transport occurred over tropical and subtropical high pressure regions where winds were light. Index values from NCEP-NCAR were 2-3 times larger than that determined from GOES. This difference resulted from large zonal wind differences and an apparent overestimate of upper-tropospheric moisture in the reanalysis model. A comparison of the satellite-derived monthly

  7. Validation of three satellite-derived databases of surface solar radiation using measurements performed at 42 stations in Brazil

    Science.gov (United States)

    Thomas, Claire; Wey, Etienne; Blanc, Philippe; Wald, Lucien

    2016-06-01

    The SoDa website (www.soda-pro.com) is populated with numerous solar-related Web services. Among them, three satellite-derived irradiation databases can be manually or automatically accessed to retrieve radiation values within the geographical coverage of the Meteosat Second Generation (MSG) satellite: the two most advanced versions of the HelioClim-3 database (versions 4 and 5, respectively HC3v4 and HC3v5), and the CAMS radiation service. So far, these databases have been validated against measurements of several stations in Europe and North Africa only. As the quality of such databases depends on the geographical regions and the climates, this paper extends this validation campaign and proposes an extensive comparison on Brazil and global irradiation received on a horizontal surface. Eleven stations from the Brazilian Institute of Space Research (INPE) network offer 1 min observations, and thirty-one stations from the Instituto Nacional de Meteorologia (INMET) network offer hourly observations. The satellite-derived estimates have been compared to the corresponding observations on hourly, daily and monthly basis. The bias relative to the mean of the measurements for HC3v5 is mostly comprised between 1 and 3 %, and that for HC3v4 between 2 and 5 %. These are very satisfactory results and they demonstrate that HC3v5, and to a lesser extent HC3v4, may be used in studies of long-term changes in SSI in Brazil. The situation is not so good with CAMS radiation service for which the relative bias is mostly comprised between 5 and 10 %. For hourly irradiation, the relative RMSE ranges from 15 to 33 %. The correlation coefficient is very large for all stations and the three databases, with an average of 0.96. The three databases reproduce well the hour from hour changes in SSI. The errors show a tendency to increase with the viewing angle of the MSG satellite. They are greater in tropical areas where the relative humidity in the atmosphere is important. It is concluded

  8. Application of satellite derived information for disaster risk reduction: vulnerability assessment for southwest coast of Pakistan

    Science.gov (United States)

    Rafiq, Lubna; Blaschke, Thomas; Zeil, Peter

    2010-10-01

    The SW-coast of Pakistan is vulnerable to natural disasters, such as cyclones and tsunamis. Lack of spatially referenced information is a major hinder for proper disaster risk management programs in Pakistan, but satellite remote sensing being reliable, fast and spatially referenced information can be used as an important component in various natural disaster risk reduction activities. This study aimed to investigate vulnerability of coastal communities to cyclone and tsunamis based on satellite derived information. It is observed that SPOT-5 is relevant source on threatened features with respect to certain vulnerabilities like road, settlements, infrastructure and used in preparation of hazard zonation and vulnerability maps. Landsat ETM found very useful in demarcation of flood inundated areas. The GIS integrated evaluation of LANDSAT and ASTER GDEM helps identify low lying areas most susceptible to flooding and inundation by cyclone surges and tsunamis. The GIS integrated evaluation of SPOT, LANDSAT and ASTER GDEM data helps identify areas and infrastructure most vulnerable to cyclone surges and tsunami. Additionally, analysis of the vulnerability of critical infrastructures (schools, hospitals) within hazard zones provides indicators for the degree of spatial exposure to disaster. Satellite derived information in conjunction with detailed surveys of hazard prone areas can provide comprehensive vulnerability and risk analysis.

  9. A Combined Satellite-Derived Drought Indicator to Support Humanitarian Aid Organizations

    Directory of Open Access Journals (Sweden)

    Markus Enenkel

    2016-04-01

    Full Text Available Governments, aid organizations and researchers are struggling with the complexity of detecting and monitoring drought events, which leads to weaknesses regarding the translation of early warnings into action. Embedded in an advanced decision-support framework for Doctors without Borders (Médecins sans Frontières, this study focuses on identifying the added-value of combining different satellite-derived datasets for drought monitoring and forecasting in Ethiopia. The core of the study is the improvement of an existing drought index via methodical adaptations and the integration of various satellite-derived datasets. The resulting Enhanced Combined Drought Index (ECDI links four input datasets (rainfall, soil moisture, land surface temperature and vegetation status. The respective weight of each input dataset is calculated for every grid point at a spatial resolution of 0.25 degrees (roughly 28 kilometers. In the case of data gaps in one input dataset, the weights are automatically redistributed to other available variables. Ranking the years 1992 to 2014 according to the ECDI-based warning levels allows for the identification of all large-scale drought events in Ethiopia. Our results also indicate a good match between the ECDI-based drought warning levels and reported drought impacts for both the start and the end of the season.

  10. Preliminary survey on site-adaptation techniques for satellite-derived and reanalysis solar radiation datasets

    Energy Technology Data Exchange (ETDEWEB)

    Polo, J.; Wilbert, S.; Ruiz-Arias, J. A.; Meyer, R.; Gueymard, C.; Súri, M.; Martín, L.; Mieslinger, T.; Blanc, P.; Grant, I.; Boland, J.; Ineichen, P.; Remund, J.; Escobar, R.; Troccoli, A.; Sengupta, M.; Nielsen, K. P.; Renne, D.; Geuder, N.; Cebecauer, T.

    2016-07-01

    At any site, the bankability of a projected solar power plant largely depends on the accuracy and general quality of the solar radiation data generated during the solar resource assessment phase. The term 'site adaptation' has recently started to be used in the framework of solar energy projects to refer to the improvement that can be achieved in satellite-derived solar irradiance and model data when short-term local ground measurements are used to correct systematic errors and bias in the original dataset. This contribution presents a preliminary survey of different possible techniques that can improve long-term satellite-derived and model-derived solar radiation data through the use of short-term on-site ground measurements. The possible approaches that are reported here may be applied in different ways, depending on the origin and characteristics of the uncertainties in the modeled data. This work, which is the first step of a forthcoming in-depth assessment of methodologies for site adaptation, has been done within the framework of the International Energy Agency Solar Heating and Cooling Programme Task 46 'Solar Resource Assessment and Forecasting.'

  11. Modelling LAI at a regional scale with ISBA-A-gs: comparison with satellite-derived LAI over southwestern France

    Directory of Open Access Journals (Sweden)

    A. Brut

    2009-08-01

    Full Text Available A CO2-responsive land surface model (the ISBA-A-gs model of Météo-France is used to simulate photosynthesis and Leaf Area Index (LAI in southwestern France for a 3-year period (2001–2003. A domain of about 170 000 km2 is covered at a spatial resolution of 8 km. The capability of ISBA-A-gs to reproduce the seasonal and the interannual variability of LAI at a regional scale, is assessed with satellite-derived LAI products. One originates from the CYCLOPES programme using SPOT/VEGETATION data, and two products are based on MODIS data. The comparison reveals discrepancies between the satellite LAI estimates and between satellite and simulated LAI values, both in their intensity and in the timing of the leaf onset. The model simulates higher LAI values for the C3 crops than the satellite observations, which may be due to a saturation effect within the satellite signal or to uncertainties in model parameters. The simulated leaf onset presents a significant delay for C3 crops and mountainous grasslands. In-situ observations at a mid-altitude grassland site show that the generic temperature response of photosynthesis used in the model is not appropriate for plants adapted to the cold climatic conditions of the mountainous areas. This study demonstrates the potential of LAI remote sensing products for identifying and locating models' shortcomings at a regional scale.

  12. Modelling LAI at a regional scale with ISBA-A-gs: comparison with satellite-derived LAI over southwestern France

    Directory of Open Access Journals (Sweden)

    A. Brut

    2009-04-01

    Full Text Available A CO2-responsive land surface model (the ISBA-A-gs model of Météo-France is used to simulate photosynthesis and Leaf Area Index (LAI in southwestern France for a 3-year period (2001–2003. A domain of about 170 000 km2 is covered at a spatial resolution of 8 km. The capability of ISBA-A-gs to reproduce the seasonal and the inter-annual variability of LAI at a regional scale, is assessed with two satellite-derived LAI products. One originates from the CYCLOPES programme using SPOT/VEGETATION data, and the second is based on MODIS data. The comparison reveals discrepancies between the two satellite LAI estimates and between satellite and simulated LAI values, both in their intensity and in the timing of the leaf onset. The model simulates higher LAI values for the C3 crops and coniferous trees than the satellite observations, which may be due to a saturation effect within the satellite signal. The simulated leaf onset presents a significant delay for mountainous grasslands. In-situ observations at a mid-altitude grassland site show that the generic temperature response of photosynthesis used in the model is not appropriate for plants adapted to the cold climatic conditions of the mountainous areas. This study demonstrates the potential of LAI remote sensing products for identifying and locating models' shortcomings at a regional scale.

  13. Modelling LAI at a regional scale with ISBA-A-gs: comparison with satellite-derived LAI over southwestern France

    Science.gov (United States)

    Brut, A.; Rüdiger, C.; Lafont, S.; Roujean, J.-L.; Calvet, J.-C.; Jarlan, L.; Gibelin, A.-L.; Albergel, C.; Le Moigne, P.; Soussana, J.-F.; Klumpp, K.

    2009-04-01

    A CO2-responsive land surface model (the ISBA-A-gs model of Météo-France) is used to simulate photosynthesis and Leaf Area Index (LAI) in southwestern France for a 3-year period (2001-2003). A domain of about 170 000 km2 is covered at a spatial resolution of 8 km. The capability of ISBA-A-gs to reproduce the seasonal and the inter-annual variability of LAI at a regional scale, is assessed with two satellite-derived LAI products. One originates from the CYCLOPES programme using SPOT/VEGETATION data, and the second is based on MODIS data. The comparison reveals discrepancies between the two satellite LAI estimates and between satellite and simulated LAI values, both in their intensity and in the timing of the leaf onset. The model simulates higher LAI values for the C3 crops and coniferous trees than the satellite observations, which may be due to a saturation effect within the satellite signal. The simulated leaf onset presents a significant delay for mountainous grasslands. In-situ observations at a mid-altitude grassland site show that the generic temperature response of photosynthesis used in the model is not appropriate for plants adapted to the cold climatic conditions of the mountainous areas. This study demonstrates the potential of LAI remote sensing products for identifying and locating models' shortcomings at a regional scale.

  14. Spatial Correlation of Satellite-Derived PM2.5 with Hospital Admissions for Respiratory Diseases

    Directory of Open Access Journals (Sweden)

    Ching-Ju Liu

    2016-11-01

    Full Text Available Respiratory diseases, particularly allergic rhinitis, are spatially and temporally correlated with the ground PM2.5 level. A study of the correlation between the two factors should therefore account for spatiotemporal variations. Satellite observation has the advantage of wide spatial coverage over pin-point style ground-based in situ monitoring stations. Therefore, the current study used both ground measurement and satellite data sets to investigate the spatial and temporal correlation of satellite-derived PM2.5 with respiratory diseases. This study used 4-year satellite data and PM2.5 levels of the period at eight stations in Taiwan to obtain the spatial and temporal relationship between aerosol optical depth (AOD and PM2.5. The AOD-PM2.5 model was further examined using the cross-validation (CV technique and was found to have high reliability compared with similar models. The model was used to obtain satellite-derived PM2.5 levels and to analyze the hospital admissions for allergic rhinitis in 2008. The results suggest that adults (18–65 years and children (3–18 years are the most vulnerable groups to the effect of PM2.5 compared with infants and elderly people. This result may be because the two affected age groups spend longer time outdoors. This result may also be attributed to the long-range PM2.5 transport from upper stream locations and the atmospheric circulation patterns, which are significant in spring and fall. The results of the current study suggest that additional environmental factors that might be associated with respiratory diseases should be considered in future studies.

  15. Can satellite-derived water surface changes be used to calibrate a hydrodynamic model?

    Science.gov (United States)

    Revilla-Romero, Beatriz; Beck, Hylke; Salamon, Peter; Burek, Peter; de Roo, Ad; Thielen, Jutta

    2015-04-01

    The limited availability of recent ground observational data is one of the main challenges for validation of hydrodynamic models. This is especially relevant for real-time global applications such as flood forecasting models. In this study, we aim to use remotely-sensed data from the Global Flood Detection System (GFDS) as a proxy of river discharge time series and test its value through calibration of the hydrological model LISFLOOD. This was carried out for the time period 1998-2010 at 40 sites in Africa, Europe, North America and South America by calibrating the parameters that control the flow routing and groundwater processes. We compared the performance of the calibrated simulated discharge time series that used satellite-derived data with the ground discharge time series. Furthermore, we compared it with the independent calibrated run that used ground data and also, to the non-calibrated simulated discharge time series. The non-calibrated set up used a set of parameters which values were predefined by expert-knowledge. This is currently being used by the LISFLOOD set up model embedded in the pre-operational Global Flood Awareness System (GloFAS). The results of this study showed that the satellite surface water changes from the Global Flood Detection System can be used as a proxy of river discharge data, through the demonstration of its added value for model calibration and validation. Using satellite-derived data, the skill scores obtained by the calibrated simulated model discharge improved when comparing to non-calibrated simulated time series. Calibration, post-processing and data assimilation strategies of satellite data as a proxy for streamflow data within the global hydrological model are outlined and discussed.

  16. Web TA Production (WebTA)

    Data.gov (United States)

    US Agency for International Development — WebTA is a web-based time and attendance system that supports USAID payroll administration functions, and is designed to capture hours worked, leave used and...

  17. Linking Satellite-Derived Fire Counts to Satellite-Derived Weather Data in Fire Prediction Models to Forecast Extreme Fires in Siberia

    Science.gov (United States)

    Westberg, D. J.; Soja, A. J.; Stackhouse, P. W.

    2009-12-01

    Fire is the dominant disturbance that precipitates ecosystem change in boreal regions, and fire is largely under the control of weather and climate. Fire frequency, fire severity, area burned and fire season length are predicted to increase in boreal regions under climate change scenarios. Therefore to predict fire weather and ecosystem change, we must understand the factors that influence fire regimes and at what scale these are viable. The Canadian Fire Weather Index (FWI), developed by the Canadian Forestry Service, is used for this comparison, and it is calculated using local noon surface-level air temperature, relative humidity, wind speed, and daily (noon-noon) rainfall. The FWI assesses daily forest fire burning potential. Large-scale FWI are calculated at the NASA Langley Research Center (LaRC) using NASA Goddard Earth Observing System version 4 (GEOS-4) large-scale reanalysis and NASA Global Precipitation Climatology Project (GPCP) data. The GEOS-4 reanalysis weather data are 3-hourly interpolated to 1-hourly data at a 1ox1o resolution and the GPCP precipitation data are also at 1ox1o resolution. In previous work focusing on the fire season in Siberia in 1999 and 2002, we have shown the combination of GEOS-4 weather data and Global Precipitation Climatology Project (GPCP) precipitation data compares well to ground-based weather data when used as inputs for FWI calculation. The density and accuracy of Siberian surface station data can be limited, which leads to results that are not representative of the spatial reality. GEOS-4/GPCP-dervied FWI can serve to spatially enhance current and historic FWI, because these data are spatially and temporally consistency. The surface station and model reanalysis derived fire weather indices compared well spatially, temporally and quantitatively, and increased fire activity compares well with increasing FWI ratings. To continue our previous work, we statistically compare satellite-derived fire counts to FWI categories at

  18. Surface radiation at sea validation of satellite-derived data with shipboard measurements

    Directory of Open Access Journals (Sweden)

    Hein Dieter Behr

    2009-03-01

    Full Text Available Quality-controlled and validated radiation products are the basis for their ability to serve the climate and solar energy community. Satellite-derived radiation fluxes are well preferred for this task as they cover the whole research area in time and space. In order to monitor the accuracy of these data, validation with well maintained and calibrated ground based measurements is necessary. Over sea, however, long-term accurate reference data sets from calibrated instruments recording radiation are scarce. Therefore data from research vessels operating at sea are used to perform a reasonable validation. A prerequisite is that the instruments on board are maintained as well as land borne stations. This paper focuses on the comparison of radiation data recorded on board of the German Research Vessel "Meteor" during her 13 months cruise across the Mediterranean and the Black Sea with CM-SAF products using NOAA- and MSG-data (August 2006-August 2007: surface incoming short-wave radiation (SIS and surface downward long-wave radiation (SDL. Measuring radiation fluxes at sea causes inevitable errors, e.g.shadowing of fields of view of the radiometers by parts of the ship. These ship-inherent difficulties are discussed at first. A comparison of pairs of ship-recorded and satellite-derived mean fluxes for the complete measuring period delivers a good agreement: the mean bias deviation (MBD for SIS daily means is −7.6 W/m2 with a median bias of −4 W/m2 and consistently the MBD for monthly means is −7.3 W/m2, for SDL daily means the MBD is 8.1 and 6 W/m2 median bias respectively. The MBD for monthly means is 8.2 W/m2. The variances of the daily means (ship and satellite have the same annual courses for both fluxes. No significant dependence of the bias on the total cloud cover recorded according to WMO (1969 has been found. The results of the comparison between ship-based observations and satellite retrieved surface radiation reveal the good accuracy

  19. Satellite Derived Volcanic Ash Product Inter-Comparison in Support to SCOPE-Nowcasting

    Science.gov (United States)

    Siddans, Richard; Thomas, Gareth; Pavolonis, Mike; Bojinski, Stephan

    2016-04-01

    In support of aeronautical meteorological services, WMO organized a satellite-based volcanic ash retrieval algorithm inter-comparison activity, to improve the consistency of quantitative volcanic ash products from satellites, under the Sustained, Coordinated Processing of Environmental Satellite Data for Nowcasting (SCOPEe Nowcasting) initiative (http:/ jwww.wmo.int/pagesjprogjsatjscopee nowcasting_en.php). The aims of the intercomparison were as follows: 1. Select cases (Sarychev Peak 2009, Eyjafyallajökull 2010, Grimsvötn 2011, Puyehue-Cordón Caulle 2011, Kirishimayama 2011, Kelut 2014), and quantify the differences between satellite-derived volcanic ash cloud properties derived from different techniques and sensors; 2. Establish a basic validation protocol for satellite-derived volcanic ash cloud properties; 3. Document the strengths and weaknesses of different remote sensing approaches as a function of satellite sensor; 4. Standardize the units and quality flags associated with volcanic cloud geophysical parameters; 5. Provide recommendations to Volcanic Ash Advisory Centers (VAACs) and other users on how to best to utilize quantitative satellite products in operations; 6. Create a "road map" for future volcanic ash related scientific developments and inter-comparison/validation activities that can also be applied to SO2 clouds and emergent volcanic clouds. Volcanic ash satellite remote sensing experts from operational and research organizations were encouraged to participate in the inter-comparison activity, to establish the plans for the inter-comparison and to submit data sets. RAL was contracted by EUMETSAT to perform a systematic inter-comparison of all submitted datasets and results were reported at the WMO International Volcanic Ash Inter-comparison Meeting to held on 29 June - 2 July 2015 in Madison, WI, USA (http:/ /cimss.ssec.wisc.edujmeetings/vol_ash14). 26 different data sets were submitted, from a range of passive imagers and spectrometers and

  20. Model-simulated and Satellite-derived Leaf Area Index (LAI) Comparisons Across Multiple Spatial Scales

    Science.gov (United States)

    Iiames, J. S., Jr.; Cooter, E. J.

    2016-12-01

    Leaf Area Index (LAI) is an important parameter in assessing vegetation structure for characterizing forest canopies over large areas at broad spatial scales using satellite remote sensing data. However, satellite-derived LAI products can be limited by obstructed atmospheric conditions yielding sub-optimal values, or complete non-returns. The United States Environmental Protection Agency's Exposure Methods and Measurements and Computational Exposure Divisions are investigating the viability of supplemental modelled LAI inputs into satellite-derived data streams to support various regional and local scale air quality models for retrospective and future climate assessments. In this present study, one-year (2002) of plot level stand characteristics at four study sites located in Virginia and North Carolina (USA) are used to calibrate species-specific plant parameters in a semi-empirical biogeochemical model. The Environmental Policy Integrated Climate (EPIC) model was designed primarily for managed agricultural field crop ecosystems, but also includes managed woody species that span both xeric and mesic sites (e.g., mesquite, pine, oak, etc.). LAI was simulated using EPIC at a 4 km2 and 12 km2 grid coincident with the regional Community Multiscale Air Quality Model (CMAQ) grid. LAI comparisons were made between model-simulated and MODIS-derived LAI. Field/satellite-upscaled LAI was also compared to the corresponding MODIS LAI value. Preliminary results show field/satellite-upscaled LAI (1 km2) was 1.5 to 3 times smaller than that with the corresponding 1 km2 MODIS LAI for all four sites across all dates, with the largest discrepancies occurring at leaf-out and leaf senescence periods. Simulated LAI/MODIS LAI comparison results will be presented at the conference. Disclaimer: This work is done in support of EPA's Sustainable Healthy Communities Research Program. The U.S. Environmental Protection Agency funded and conducted the research described in this paper. Although

  1. Validation of Satellite-Derived Sea Surface Temperatures for Waters around Taiwan

    Directory of Open Access Journals (Sweden)

    Ming-An Lee

    2005-01-01

    Full Text Available In order to validate the Advanced Very High Resolution Radiometer (AVHRR-derived sea surface temperatures (SST of the waters around Taiwan, we generated a match-up data set of 961 pairs, which included in situ SSTs and concurrent AVHRR measurements for the period of 1998 to 2002. Availability of cloud-free images, i.e., images with more than 85% of cloud-free area in their coverage, was about 2.23% of all AVHRR images during the study period. The range of in situ SSTs was from _ to _ The satellite derived-SSTs through MCSST and NLSST algorithms were linearly related to the in situ SSTs with correlation coefficients of 0.985 and 0.98, respectively. The MCSSTs and NLSSTs had small biases of 0.009 _ and 0.256 _ with root mean square deviations of 0.64 _ and 0.801 _ respectively, therefore the AVHRR-based MCSSTs and NLSSTs had high accuracy in the seas around Taiwan.

  2. Satellite derived precipitation and freshwater flux variability and its dependence on the North Atlantic Oscillation

    Science.gov (United States)

    Andersson, Axel; Bakan, Stephan; Graßl, Hartmut

    2010-08-01

    The variability of satellite retrieved precipitation and freshwater flux from the `Hamburg Ocean Atmosphere Parameters and Fluxes from Satellite Data' (HOAPS) is assessed with special emphasis on the `North Atlantic Oscillation' (NAO). To cover also land areas, a novel combination of the satellite derived precipitation climatology with the rain gauge based `Full Data Reanalysis Product Version 4', of the `Global Precipitation Climatology Centre' (GPCC) is used. This yields unique high-resolution, quasi-global precipitation fields compiled from two independent data sources. Over the ocean, the response of the freshwater balance and the related parameters to the NAO is investigated for the first time by using a purely satellite based data set. A strong dependence of precipitation patterns to the state of the NAO is found. On synoptic scale this is in accordance with earlier findings by other satellite based and reanalysis products. Furthermore, the consistency of the combined HOAPS-3/GPCC data set allows also detailed regional analyses of precipitation patterns. The response of HOAPS-3 freshwater flux to the NAO is dominated by precipitation at mid and high latitudes, while for the subtropical regions the feedback of the evaporation is stronger.

  3. Evaluating a satellite-based seasonal evapotranspiration product and identifying its relationship with other satellite-derived products and crop yield: A case study for Ethiopia

    Science.gov (United States)

    Tadesse, Tsegaye; Senay, Gabriel B.; Berhan, Getachew; Regassa, Teshome; Beyene, Shimelis

    2015-01-01

    Satellite-derived evapotranspiration anomalies and normalized difference vegetation index (NDVI) products from Moderate Resolution Imaging Spectroradiometer (MODIS) data are currently used for African agricultural drought monitoring and food security status assessment. In this study, a process to evaluate satellite-derived evapotranspiration (ETa) products with a geospatial statistical exploratory technique that uses NDVI, satellite-derived rainfall estimate (RFE), and crop yield data has been developed. The main goal of this study was to evaluate the ETa using the NDVI and RFE, and identify a relationship between the ETa and Ethiopia’s cereal crop (i.e., teff, sorghum, corn/maize, barley, and wheat) yields during the main rainy season. Since crop production is one of the main factors affecting food security, the evaluation of remote sensing-based seasonal ETa was done to identify the appropriateness of this tool as a proxy for monitoring vegetation condition in drought vulnerable and food insecure areas to support decision makers. The results of this study showed that the comparison between seasonal ETa and RFE produced strong correlation (R2 > 0.99) for all 41 crop growing zones in Ethiopia. The results of the spatial regression analyses of seasonal ETa and NDVI using Ordinary Least Squares and Geographically Weighted Regression showed relatively weak yearly spatial relationships (R2 cropping zones. However, for each individual crop zones, the correlation between NDVI and ETa ranged between 0.3 and 0.84 for about 44% of the cropping zones. Similarly, for each individual crop zones, the correlation (R2) between the seasonal ETa anomaly and de-trended cereal crop yield was between 0.4 and 0.82 for 76% (31 out of 41) of the crop growing zones. The preliminary results indicated that the ETa products have a good predictive potential for these 31 identified zones in Ethiopia. Decision makers may potentially use ETa products for monitoring cereal crop yields and

  4. Potential for a biogenic influence on cloud microphysics over the ocean: a correlation study with satellite-derived data

    Directory of Open Access Journals (Sweden)

    A. Lana

    2012-09-01

    Full Text Available Aerosols have a large potential to influence climate through their effects on the microphysics and optical properties of clouds and, hence, on the Earth's radiation budget. Aerosol–cloud interactions have been intensively studied in polluted air, but the possibility that the marine biosphere plays an important role in regulating cloud brightness in the pristine oceanic atmosphere remains largely unexplored. We used 9 yr of global satellite data and ocean climatologies to derive parameterizations of the temporal variability of (a production fluxes of sulfur aerosols formed by the oxidation of the biogenic gas dimethylsulfide emitted from the sea surface; (b production fluxes of secondary organic aerosols from biogenic organic volatiles; (c emission fluxes of biogenic primary organic aerosols ejected by wind action on sea surface; and (d emission fluxes of sea salt also lifted by the wind upon bubble bursting. Series of global monthly estimates of these fluxes were correlated to series of potential cloud condensation nuclei (CCN numbers derived from satellite (MODIS. More detailed comparisons among weekly series of estimated fluxes and satellite-derived cloud droplet effective radius (re data were conducted at locations spread among polluted and clean regions of the oceanic atmosphere. The outcome of the statistical analysis was that positive correlation to CCN numbers and negative correlation to re were common at mid and high latitude for sulfur and organic secondary aerosols, indicating both might be important in seeding cloud droplet activation. Conversely, primary aerosols (organic and sea salt showed widespread positive correlations to CCN only at low latitudes. Correlations to re were more variable, non-significant or positive, suggesting that, despite contributing to large shares of the marine aerosol mass, primary aerosols are not widespread major drivers of the variability of cloud

  5. Spatial and Quantitative Comparison of Satellite-Derived Land Cover Products over China

    Institute of Scientific and Technical Information of China (English)

    GAO Hao; JIA Gen-Suo

    2012-01-01

    Because land cover plays an important role in global climate change studies, assessing the agreement among different land cover products is critical. Significant discrepancies have been reported among satellite-derived land cover products, especially at the regional scale. Dif- ferent classification schemes are a key obstacle to the comparison of products and are considered the main fac- tor behind the disagreement among the different products. Using a feature-based overlap metric, we investigated the degree of spatial agreement and quantified the overall and class-specific agreement among the Moderate Resolution Imaging Spectoradiometer (MODIS), Global Land Cover 2000 (GLC2000), and the National Land Cover/Use Data- sets (NLCD) products, and the author assessed the prod- ucts by ground reference data at the regional scale over China. The areas with a low degree of agreement mostly occurred in heterogeneous terrain and transition zones, while the areas with a high degree of agreement occurred in major plains and areas with homogeneous vegetation. The overall agreement of the MODIS and GLC2000 products was 50.8% and 52.9%, and the overall accuracy was 50.3% and 41.9%, respectively. Class-specific agree- ment or accuracy varied significantly. The high-agreement classes are water, grassland, cropland, snow and ice, and bare areas, whereas classes with low agreement are shru- bland and wetland in both MODIS and GLC2000. These characteristics of spatial patterns and quantitative agree- ment could be partly explained by the complex landscapes, mixed vegetation, low separability of spectro-temporal- texture signals, and coarse pixels. The differences of class definition among different the classification schemes also affects the agreement. Each product had its advantages and limitations, but neither the overall accuracy nor the class-specific accuracy could meet the requirements of climate modeling.

  6. Trends in a satellite-derived vegetation index and environmental variables in a restored brackish lagoon

    Directory of Open Access Journals (Sweden)

    Ji Yoon Kim

    2015-07-01

    Full Text Available We evaluated relative influence of climatic variables on the plant productivity after lagoon restoration. Chilika Lagoon, the largest brackish lake ecosystem in East Asia, experienced severe problems such as excessive dominance of freshwater exotic plants and rapid debasement of biodiversity associated with decreased hydrologic connectivity between the lagoon and the ocean. To halt the degradation of the lagoon ecosystem, the Chilika Development Authority implemented a restoration project, creating a new channel to penetrate the barrier beach of the lagoon. Using a satellite-derived normalized difference vegetation index (NDVI dataset, we compared the trend of vegetation changes after the lagoon restoration, from April 1998 to May 2014. The time series of NDVI data were decomposed into trend, seasonal, and random components using a local regression method. The results were visualized to understand the traits of spatial distribution in the lagoon. The NDVI trend, indicative of primary productivity, decreased rapidly during the restoration period, and gradually increased (slope coefficient: 2.1×10−4, p<0.05 after two years of restoration. Level of seawater exchange had more influences on plant productivity than local precipitation in the restored lagoon. Higher El Niño/Southern Oscillation increased sea level pressure, and caused intrusion of seawater into the lagoon, and the subsequently elevated salinity decreased the annual mean NDVI. Our findings suggest that lagoon restoration plans for enhancing interconnectivity with the ocean should consider oceanographic effects due to meteorological forcing, and long-term NDVI results can be used as a valuable index for adaptive management of the restoration site.

  7. Comparison of Satellite-Derived and In-Situ Observations of Ice and Snow Surface Temperatures over Greenland

    Science.gov (United States)

    Hall, Dorothy K.; Box, Jason E.; Casey, Kimberly A.; Hook, Simon J.; Shuman, Christopher A.; Steffen, Konrad

    2008-01-01

    The most practical way to get a spatially broad and continuous measurements of the surface temperature in the data-sparse cryosphere is by satellite remote sensing. The uncertainties in satellite-derived LSTs must be understood to develop internally-consistent decade-scale land-surface temperature (LST) records needed for climate studies. In this work we assess satellite-derived "clear-sky" LST products from the Moderate Resolution Imaging Spectroradiometer (MODIS) and the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER), and LSTs derived from the Enhanced Thematic Mapper Plus (ETM+) over snow and ice on Greenland. When possible, we compare satellite-derived LSTs with in-situ air-temperature observations from Greenland Climate Network (GC-Net) automatic-weather stations (AWS). We find that MODIS, ASTER and ETM+ provide reliable and consistent LSTs under clear-sky conditions and relatively-flat terrain over snow and ice targets over a range of temperatures from -40 to 0 C. The satellite-derived LSTs agree within a relative RMS uncertainty of approx.0.5 C. The good agreement among the LSTs derived from the various satellite instruments is especially notable since different spectral channels and different retrieval algorithms are used to calculate LST from the raw satellite data. The AWS record in-situ data at a "point" while the satellite instruments record data over an area varying in size from: 57 X 57 m (ETM+), 90 X 90 m (ASTER), or to 1 X 1 km (MODIS). Surface topography and other factors contribute to variability of LST within a pixel, thus the AWS measurements may not be representative of the LST of the pixel. Without more information on the local spatial patterns of LST, the AWS LST cannot be considered valid ground truth for the satellite measurements, with RMS uncertainty approx.2 C. Despite the relatively large AWS-derived uncertainty, we find LST data are characterized by high accuracy but have uncertain absolute precision.

  8. Varying applicability of four different satellite-derived soil moisture products to global gridded crop model evaluation

    Science.gov (United States)

    Sakai, Toru; Iizumi, Toshichika; Okada, Masashi; Nishimori, Motoki; Grünwald, Thomas; Prueger, John; Cescatti, Alessandro; Korres, Wolfgang; Schmidt, Marius; Carrara, Arnaud; Loubet, Benjamin; Ceschia, Eric

    2016-06-01

    Satellite-derived daily surface soil moisture products have been increasingly available, but their applicability to global gridded crop model (GGCM) evaluation is unclear. This study compares four different soil moisture products with the flux tower site observation at 18 cropland sites across the world where either of maize, soybean, rice and wheat is grown. These products include the first and second versions of Climate Change Initiative Soil Moisture (CCISM-1 and CCISM-2) datasets distributed by the European Space Agency and two different AMSR-E (Advanced Microwave Scanning Radiometer-Earth Observing System)-derived soil moisture datasets, separately provided by the Japan Aerospace Exploration Agency (AMSRE-J) and U.S. National Aeronautics and Space Administration (AMSRE-N). The comparison demonstrates varying reliability of these products in representing major characteristics of temporal pattern of cropland soil moisture by product and crop. Possible reasons for the varying reliability include the differences in sensors, algorithms, bands and criteria used when estimating soil moisture. Both the CCISM-1 and CCISM-2 products appear the most reliable for soybean- and wheat-growing area. However, the percentage of valid data of these products is always lower than other products due to relatively strict criteria when merging data derived from multiple sources, although the CCISM-2 product has much more data with valid retrievals than the CCISM-1 product. The reliability of the AMSRE-J product is the highest for maize- and rice-growing areas and comparable to or slightly lower than the CCISM products for soybean- and wheat-growing areas. The AMSRE-N is the least reliable in most location-crop combinations. The reliability of the products for rice-growing area is far lower than that of other upland crops likely due to the extensive use of irrigation and patch distribution of rice paddy in the area examined here. We conclude that the CCISM-1, CCISM-2 and AMSRE

  9. The Optical Properties of Nanostructured Ta2O5 Films

    Institute of Scientific and Technical Information of China (English)

    Minmin Zhu; Wei Miao; Zhengjun Zhang

    2006-01-01

    Amorphous Ta2O5 films were prepared on Si (100) substrates by thermal oxidization. The film consisted of amorphous Ta2O5 nanostructure that grew vertically and compactly at a large range. It was found that Ta2O5 films became crystalline when annealed at or above 650℃ and remained amorphous below 650℃. The effects of annealing on the optical properties of Ta2O5 film were also discussed. It is estimated that the refraction indexes and the optical energy gaps of both amorphous Ta2O5 film and crystal one are stable. The optical energy gap of as-deposited Ta2O5 film is about 4.81 eV. The above results indicate that Ta2O5 films have a promising application in the optical devices.

  10. Influence of satellite-derived photolysis rates and NOx emissions on Texas ozone modeling

    Directory of Open Access Journals (Sweden)

    W. Tang

    2014-09-01

    Full Text Available Uncertain photolysis rates and emission inventory impair the accuracy of state-level ozone (O3 regulatory modeling. Past studies have separately used satellite-observed clouds to correct the model-predicted photolysis rates, or satellite-constrained top-down NOx emissions to identify and reduce uncertainties in bottom-up NOx emissions. However, the joint application of multiple satellite-derived model inputs to improve O3 State Implementation Plan (SIP modeling has rarely been explored. In this study, Geostationary Operational Environmental Satellite (GOES observations of clouds are applied to derive the photolysis rates, replacing those used in Texas SIP modeling. This changes modeled O3 concentrations by up to 80 ppb and improves O3 simulations by reducing modeled normalized mean bias (NMB and normalized mean error (NME by up to 0.1. A sector-based discrete Kalman filter (DKF inversion approach is incorporated with the Comprehensive Air Quality Model with extensions (CAMx-Decoupled Direct Method (DDM model to adjust Texas NOx emissions using a high resolution Ozone Monitoring Instrument (OMI NO2 product. The discrepancy between OMI and CAMx NO2 vertical column densities (VCD is further reduced by increasing modeled NOx lifetime and adding an artificial amount of NO2 in the upper troposphere. The sector-based DKF inversion tends to scale down area and non-road NOx emissions by 50%, leading to a 2–5 ppb decrease in ground 8 h O3 predictions. Model performance in simulating ground NO2 and O3 are improved using inverted NOx emissions, with 0.25 and 0.04 reductions in NMBs and 0.13 and 0.04 reductions in NMEs, respectively. Using both GOES-derived photolysis rates and OMI-constrained NOx emissions together reduces modeled NMB and NME by 0.05 and increases the model correlation with ground measurement in O3 simulations and makes O3 more sensitive to NOx emissions in the O3 non-attainment areas.

  11. Analysis of Satellite-Derived Arctic Tropospheric BrO Columns in Conjunction with Aircraft Measurements During ARCTAS and ARCPAC

    Science.gov (United States)

    Choi, S.; Wang, Y.; Salawitch, R. J.; Canty, T.; Joiner, J.; Zeng, T.; Kurosu, T. P.; Chance, K.; Richter, A.; Huey, L. G.; hide

    2012-01-01

    We derive tropospheric column BrO during the ARCTAS and ARCPAC field campaigns in spring 2008 using retrievals of total column BrO from the satellite UV nadir sensors OMI and GOME-2 using a radiative transfer model and stratospheric column BrO from a photochemical simulation. We conduct a comprehensive comparison of satellite-derived tropospheric BrO column to aircraft in-situ observations ofBrO and related species. The aircraft profiles reveal that tropospheric BrO, when present during April 2008, was distributed over a broad range of altitudes rather than being confined to the planetary boundary layer (PBL). Perturbations to the total column resulting from tropospheric BrO are the same magnitude as perturbations due to longitudinal variations in the stratospheric component, so proper accounting of the stratospheric signal is essential for accurate determination of satellite-derived tropospheric BrO. We find reasonably good agreement between satellite-derived tropospheric BrO and columns found using aircraft in-situ BrO profiles, particularly when satellite radiances were obtained over bright surfaces (albedo> 0.7), for solar zenith angle BrO due to surface processes (the bromine explosion) is apparent in both the OMI and GOME-2 based tropospheric columns. The wide orbital swath of OMI allows examination of the evolution of tropospheric BrO on about hourly time intervals near the pole. Low surface pressure, strong wind, and high PBL height are associated with an observed BrO activation event, supporting the notion of bromine activation by high winds over snow.

  12. Analysis of satellite-derived Arctic tropospheric BrO columns in conjunction with aircraft measurements during ARCTAS and ARCPAC

    Directory of Open Access Journals (Sweden)

    S. Choi

    2012-02-01

    Full Text Available We derive tropospheric column BrO during the ARCTAS and ARCPAC field campaigns in spring 2008 using retrievals of total column BrO from the satellite UV nadir sensors OMI and GOME-2 using a radiative transfer model and stratospheric column BrO from a photochemical simulation. We conduct a comprehensive comparison of satellite-derived tropospheric BrO column to aircraft in-situ observations of BrO and related species. The aircraft profiles reveal that tropospheric BrO, when present during April 2008, was distributed over a broad range of altitudes rather than being confined to the planetary boundary layer (PBL. Perturbations to the total column resulting from tropospheric BrO are the same magnitude as perturbations due to longitudinal variations in the stratospheric component, so proper accounting of the stratospheric signal is essential for accurate determination of satellite-derived tropospheric BrO. We find reasonably good agreement between satellite-derived tropospheric BrO and columns found using aircraft in-situ BrO profiles, particularly when satellite radiances were obtained over bright surfaces (albedo >0.7, for solar zenith angle <80° and clear sky conditions. The rapid activation of BrO due to surface processes (the bromine explosion is apparent in both the OMI and GOME-2 based tropospheric columns. The wide orbital swath of OMI allows examination of the evolution of tropospheric BrO on about hourly time intervals near the pole. Low surface pressure, strong wind, and high PBL height are associated with an observed BrO activation event, supporting the notion of bromine activation by high winds over snow.

  13. Prediction of new high pressure phase of TaB{sub 3}: First-principles

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Xiaozheng [College of Science, Inner Mongolia University of Technology, Hohhot 010051 (China); State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China); Zhao, Erjun, E-mail: ejzhao@yahoo.com [College of Science, Inner Mongolia University of Technology, Hohhot 010051 (China); Wu, Zhijian, E-mail: zjwu@ciac.ac.cn [State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China)

    2015-05-25

    Highlights: • Crystal structure of TaB{sub 3} is predicted using the evolutionary algorithm USPEX code. • The structural and mechanical properties of tantalum borides are investigated by DFT. • The stable phases are found by enthalpy-pressure relationship and convex hull. • oC16–TaB{sub 3} has a estimated hardness (41.2 GPa) and indentation strength (22.8 GPa). • High pressure is advantageous to syntheses of ruthenium Triborides oC16–TaB{sub 3}. - Abstract: The phase stability, elastic, mechanical, dynamical and electronic properties of tantalum borides, i.e., Ta{sub 2}B, TaB, Ta{sub 3}B{sub 4}, Ta{sub 5}B{sub 6}, TaB{sub 2} and TaB{sub 3}, have been investigated by first-principles. The calculated convex hull indicates that at ambient conditions, the ground state phases are tI12–Ta{sub 2}B, oC8–TaB, oC22–Ta{sub 5}B{sub 6}, oI14–Ta{sub 3}B{sub 4}, and hP3–TaB{sub 2}; while at 75 GPa, they are tI12–Ta{sub 2}B, oC8–TaB, oC22–Ta{sub 5}B{sub 6}, oI14–Ta{sub 3}B{sub 4}, hP3–TaB{sub 2} and oC16–TaB{sub 3}; oC8–TaB, oC22–Ta{sub 5}B{sub 6}, oI14–Ta{sub 3}B{sub 4}, oC16–TaB{sub 3} are the most stable phases at 120 GPa. The enthalpy-pressure relationship reveals that the hP3–TaB{sub 2} is the most stable below 75 GPa, while the predicted oC16–TaB{sub 3} becomes the most stable above 75 GPa. Combining the estimated hardness (41.2 GPa) and indentation strength (22.8 GPa) for oC16–TaB{sub 3}, it is suggested that oC16–TaB{sub 3} is hard or potential superhard. Since it is not available experimentally, further experimental synthesis could be rewarding.

  14. Comparisons between buoy-observed, satellite-derived, and modeled surface shortwave flux over the subtropical North Atlantic during the Subduction Experiment

    Energy Technology Data Exchange (ETDEWEB)

    Waliser, Duane E. [Institute for Terrestrial and Planetary Atmospheres, State University of New York, Stony Brook (United States); Weller, Robert A. [Woods Hole Oceanographic Institution, Woods Hole, Massachusetts (United States); Cess, Robert D. [Institute for Terrestrial and Planetary Atmospheres, State University of New York, Stony Brook (United States)

    1999-12-27

    satellite-derived climatologies. These comparisons showed much better and more consistent agreement, with relative bias errors ranging from about -1 to 6%. Comparisons to contemporaneous, daily-average satellite derived values show relatively good agreement as well, with relative biases of the order of 2% ({approx}3-9 W m-2) and root-mean-square differences of {approx}10% (25-30 W m-2). Aspects of the role aerosols play in the above results are discussed along with the implications of the above results on the integrity of open-ocean buoy measurements of surface shortwave flux and the possibility of using the techniques developed in this study to remotely monitor the operating condition of buoy-based shortwave radiometers. (c) 1999 American Geophysical Union.

  15. Strong contribution of autumn phenology to changes in satellite-derived growing season length estimates across Europe (1982-2011).

    Science.gov (United States)

    Garonna, Irene; de Jong, Rogier; de Wit, Allard J W; Mücher, Caspar A; Schmid, Bernhard; Schaepman, Michael E

    2014-11-01

    Land Surface Phenology (LSP) is the most direct representation of intra-annual dynamics of vegetated land surfaces as observed from satellite imagery. LSP plays a key role in characterizing land-surface fluxes, and is central to accurately parameterizing terrestrial biosphere-atmosphere interactions, as well as climate models. In this article, we present an evaluation of Pan-European LSP and its changes over the past 30 years, using the longest continuous record of Normalized Difference Vegetation Index (NDVI) available to date in combination with a landscape-based aggregation scheme. We used indicators of Start-Of-Season, End-Of-Season and Growing Season Length (SOS, EOS and GSL, respectively) for the period 1982-2011 to test for temporal trends in activity of terrestrial vegetation and their spatial distribution. We aggregated pixels into ecologically representative spatial units using the European Landscape Classification (LANMAP) and assessed the relative contribution of spring and autumn phenology. GSL increased significantly by 18-24 days decade(-1) over 18-30% of the land area of Europe, depending on methodology. This trend varied extensively within and between climatic zones and landscape classes. The areas of greatest growing-season lengthening were the Continental and Boreal zones, with hotspots concentrated in southern Fennoscandia, Western Russia and pockets of continental Europe. For the Atlantic and Steppic zones, we found an average shortening of the growing season with hotspots in Western France, the Po valley, and around the Caspian Sea. In many zones, changes in the NDVI-derived end-of-season contributed more to the GSL trend than changes in spring green-up, resulting in asymmetric trends. This underlines the importance of investigating senescence and its underlying processes more closely as a driver of LSP and global change.

  16. Statistical modeling of phenological phases in Poland based on coupling satellite derived products and gridded meteorological data

    Science.gov (United States)

    Czernecki, Bartosz; Jabłońska, Katarzyna; Nowosad, Jakub

    2016-04-01

    The aim of the study was to create and evaluate different statistical models for reconstructing and predicting selected phenological phases. This issue is of particular importance in Poland where national-wide phenological monitoring was abandoned in the middle of 1990s and the reactivated network was established in 2006. Authors decided to evaluate possibilities of using a wide-range of statistical modeling techniques to create synthetic archive dataset. Additionally, a robust tool for predicting the most distinguishable phenophases using only free of charge data as predictors was created. Study period covers the years 2007-2014 and contains only quality-controlled dataset of 10 species and 14 phenophases. Phenological data used in this study originates from the manual observations network run by the Institute of Meteorology and Water Management - National Research Institute (IMGW-PIB). Three kind of data sources were used as predictors: (i) satellite derived products, (ii) preprocessed gridded meteorological data, and (iii) spatial properties (longitude, latitude, altitude) of the monitoring site. Moderate-Resolution Imaging Spectroradiometer (MODIS) level-3 vegetation products were used for detecting onset dates of particular phenophases. Following indices were used: Normalized Difference Vegetation Index (NDVI), Enhanced Vegetation Index (EVI), Leaf Area Index (LAI), and Fraction of Photosynthetically Active Radiation (fPAR). Additionally, Interactive Multisensor Snow and Ice Mapping System (IMS) products were chosen to detect occurrence of snow cover. Due to highly noisy data, authors decided to take into account pixel reliability information. Besides satellite derived products (NDVI, EVI, FPAR, LAI, Snow cover), a wide group of observational data and agrometeorological indices derived from the European Climate Assessment & Dataset (ECA&D) were used as a potential predictors: cumulative growing degree days (GDD), cumulative growing precipitation days (GPD

  17. Oceanic Weather Decision Support for Unmanned Global Hawk Science Missions into Hurricanes with Tailored Satellite Derived Products

    Science.gov (United States)

    Feltz, Wayne; Griffin, Sarah; Velden, Christopher; Zipser, Ed; Cecil, Daniel; Braun, Scott

    2017-04-01

    The purpose of this presentation is to identify in-flight hazards to high-altitude aircraft, namely the Global Hawk. The Global Hawk was used during Septembers 2012-2016 as part of two NASA funded Hurricane Sentinel-3 field campaigns to over-fly hurricanes in the Atlantic Ocean. This talk identifies the cause of severe turbulence experienced over Hurricane Emily (2005) and how a combination of NOAA funded GOES-R algorithm derived cloud top heights/tropical overshooting tops using GOES-13/SEVIRI imager radiances, and lightning information are used to identify areas of potential turbulence for near real-time navigation decision support. Several examples will demonstrate how the Global Hawk pilots remotely received and used real-time satellite derived cloud and lightning detection information to keep the aircraft safely above clouds and avoid regions of potential turbulence.

  18. Handling of subpixel structures in the application of satellite derived irradiance data for solar energy system analysis - a review

    Science.gov (United States)

    Beyer, Hans Georg

    2016-04-01

    With the increasing availability of satellite derived irradiance information, this type of data set is more and more in use for the design and operation of solar energy systems, most notably PV- and CSP-systems. By this, the need for data measured on-site is reduced. However, due to basic limitations of the satellite-derived data, several requirements put by the intended application cannot be coped with this data type directly. Traw satellite information has to be enhanced in both space and time resolution by additional information to be fully applicable for all aspects of the modelling od solar energy systems. To cope with this problem, several individual and collaborative projects had been performed in the recent years or are ongoing. Approaches are on one hand based on pasting synthesized high-resolution data into the low-resolution original sets. Pre-requite is an appropriate model, validated against real world data. For the case of irradiance data, these models can be extracted either directly from ground measured data sets or from data referring to the cloud situation as gained from the images of sky cameras or from monte -carlo initialized physical models. The current models refer to the spatial structure of the cloud fields. Dynamics are imposed by moving the cloud structures according to a large scale cloud motion vector, either extracted from the dynamics interfered from consecutive satellite images or taken from a meso-scale meteorological model. Dynamic irradiance information is then derived from the cloud field structure and the cloud motion vector. This contribution, which is linked to subtask A - Solar Resource Applications for High Penetration of Solar Technologies - of IEA SHC task 46, will present the different approaches and discuss examples in view of validation, need for auxiliary information and respective general applicability.

  19. Determining the Pixel-to-Pixel Uncertainty in Satellite-Derived SST Fields

    Directory of Open Access Journals (Sweden)

    Fan Wu

    2017-08-01

    Full Text Available The primary measure of the quality of sea surface temperature (SST fields obtained from satellite-borne infrared sensors has been the bias and variance of matchups with co-located in-situ values. Because such matchups tend to be widely separated, these bias and variance estimates are not necessarily a good measure of small scale (several pixels gradients in these fields because one of the primary contributors to the uncertainty in satellite retrievals is atmospheric contamination, which tends to have large spatial scales compared with the pixel separation of infrared sensors. Hence, there is not a good measure to use in selecting SST fields appropriate for the study of submesoscale processes and, in particular, of processes associated with near-surface fronts, both of which have recently seen a rapid increase in interest. In this study, two methods are examined to address this problem, one based on spectra of the SST data and the other on their variograms. To evaluate the methods, instrument noise was estimated in Level-2 Visible-Infrared Imager-Radiometer Suite (VIIRS and Advanced Very High Resolution Radiometer (AVHRR SST fields of the Sargasso Sea. The two methods provided very nearly identical results for AVHRR: along-scan values of approximately 0.18 K for both day and night and along-track values of 0.21 K for day and night. By contrast, the instrument noise estimated for VIIRS varied by method, scan geometry and day-night. Specifically, daytime, along-scan (along-track, spectral estimates were found to be approximately 0.05 K (0.08 K and the corresponding nighttime values of 0.02 K (0.03 K. Daytime estimates based on the variogram were found to be 0.08 K (0.10 K with the corresponding nighttime values of 0.04 K (0.06 K. Taken together, AVHRR instrument noise is significantly larger than VIIRS instrument noise, along-track noise is larger than along-scan noise and daytime levels are higher than nighttime levels. Given the similarity of

  20. Satellite-derived primary productivity and its spatial and temporal variability in the China seas%中国近海初级生产力的遥感研究及其时空演化

    Institute of Scientific and Technical Information of China (English)

    檀赛春; 石广玉

    2006-01-01

    The spatial and temporal variability of primary productivity in the China seas from 2003 to 2005 was estimated using a size-fractionated primary productivity model. Primary productivity estimated from satellite-derived data showed spatial and temporal variability. Annual averaged primary productivity levels were 564.39, 363.08, 536.47, 413.88, 195.77, and 100.09 gCm-2a-1 in the Bohai Sea, northern Yellow Sea (YS), southern YS, northern East China Sea (ECS), southern ECS, and South China Sea (SCS), respectively. Peaks of primary productivity appeared in spring (April-June) and fall (October and November) in the northern YS, southern YS, and southern ECS, while a single peak (June) appeared in the Bohai Sea and northern ECS. The SCS had two peaks in primary productivity, but these peaks occurred in winter (January) and summer (August), with the winter peak far higher than the summer peak. Monthly averaged primary productivity values from 2003 to 2005 in the Bohai Sea and southern YS were higher than those in the other four seas during most months, while those in the southern ECS and SCS were the lowest. Primary productivity in spring (March-June in the southern ECS and April-July in the other five areas) contributed approximately 41% on average to the annual primary productivity in all the study seas except the SCS. The largest interannual variability also occurred in spring (average standard deviation = 6.68), according to the satellite-derived estimates. The contribution during fall (October-January in the southern ECS and August-November in the other five areas) was approximately 33% on average; the primary productivity during this period also showed interannual variability. However, in the SCS, the winter (December-March) contribution was the highest (about 42%), while the spring (April-July) contribution was the lowest (28%). The SCS did share a feature with the other five areas: the larger the contribution, the larger the interannual variability. Spatial and

  1. Pd/Ta2O5/SiC Schottky-diode hydrogen sensors formed by using rapid thermal oxidation of Ta thin films

    Science.gov (United States)

    Joo, Sung-Jae; Choi, Je Hoon; Kim, Seong Jeen; Kim, Sang-Cheol

    2013-11-01

    Pd/Ta2O5/SiC Schottky-diode hydrogen sensors were fabricated, and their hydrogen gas sensing performance was investigated at 573 K and 773 K. Interfacial Ta2O5 films of 120 nm in thickness were formed by using rapid thermal oxidation (RTO) of the sputtered Ta films on SiC. The crystallinity of the Ta and the Ta2O5 films were characterized by using X-ray diffraction (XRD). As-sputtered Ta films on 4H-SiC are composed of α-Ta (body-centered-cubic) and β-Ta (tetragonal), and α-Ta (110) is the dominant orientation. After RTO at 573 K, the Ta films are converted to β-Ta2O5 (orthorhombic). The diode sensors show high sensitivity to H2 even at the low H2 concentration of 500 ppm, and the voltage change of the sensor upon H2 exposure is proportional to the H2 concentration in the range of 500 ˜ 2000 ppm at 573 K. The response voltage ΔV is shown to arise mostly from the change in the series resistance component of the sensor upon H2 exposure; the main origin of that change is believed to be the Ta2O5 interfacial layer. The response time t90 of the sensor at 573 K was estimated to be approximately 8 s.

  2. The annual cycle of satellite-derived sea surface temperature in the southwestern Atlantic Ocean

    Science.gov (United States)

    Podesta, Guillermo P.; Brown, Otis B.; Evans, Robert H.

    1991-01-01

    The annual cycle of sea surface temperature (SST) in the southwestern Atlantic Ocean was estimated using four years (July 1984-July 1988) of NOAA Advanced Very High Resolution Radiometer observations. High resolution satellite observations at 1-km space and daily time resolution were grided at 100-km space and 5-day time intervals to develop an analysis dataset for determination of low frequency SST variability. The integral time scale, a measure of serial correlation, was found to vary from 40 to 60 days in the domain of interest. The existence of superannual trends in the SST data was investigated, but conclusive results could not be obtained. The annual cycle (and, in particular, the annual harmonic) explains a large proportion of the SST variability. The estimated amplitude of the cycle ranges between 5 deg and 13 deg C throughout the study area, with minima in August-September and maxima in February. The resultant climatology is compared with an arbitrary 5-day satellite SST field, and with the COADS/ICE SST climatology. It was found that the higher resolution satellite-based SST climatology resolves boundary current structure and has significantly better structural agreement with the observed field.

  3. Influence of satellite-derived rainfall patterns on plague occurrence in northeast Tanzania.

    Science.gov (United States)

    Debien, Annekatrien; Neerinckx, Simon; Kimaro, Didas; Gulinck, Hubert

    2010-12-13

    In the tropics, rainfall data are seldom accurately recorded, and are often discontinuous in time. In the scope of plague-research in northeast Tanzania, we adapted previous research to reconstruct rainfall patterns at a suitable resolution (1 km), based on time series of NDVI: more accurate satellite imagery was used, in the form of MODIS NDVI, and rainfall data were collected from the TRMM sensors instead of in situ data. First, we established a significant relationship between monthly rainfall and monthly composited MODIS NDVI. The established linear relationship was then used to reconstruct historic precipitation patterns over a mountainous area in northeastern Tanzania. We validated the resulting precipitation estimates with in situ rainfall time series of three meteorological stations located in the study area. Taking the region's topography into account, a correlation coefficient of 0.66 was obtained for two of the three meteorological stations. Our results suggest that the adapted strategy can be applied fruitfully to estimate rainfall variability and seasonality, despite the underestimation of overall rainfall rates. Based on this model, rainfall in previous years (1986) is modelled to obtain a dataset with which we can compare plague occurrence in the area. A positive correlation of 82% is obtained between high rainfall rates and plague incidence with a two month lag between rainfall and plague cases. We conclude that the obtained results are satisfactory in support of the human plague research in which this study is embedded, and that this approach can be applied in other studies with similar goals.

  4. Investigation of TaC–TaB2 ceramic composites

    Indian Academy of Sciences (India)

    Behzad Mehdikhani; Gholam Hossein Borhani; Saeed Reza Bakhshi; Hamid Reza Baharvandi

    2016-02-01

    The TaC–TaB2 composition was sintered by spark plasma (SPS) at 1900–2100°C and applied pressure of 30 MPa. TaC and 2–3 wt% B4C were used as starting powders. Densification process, phase evolution, microstructure and the mechanical properties of the composites were investigated. The results indicated that the TaC–TaB2 composition could be SPS to 97% of theoretical density in 10 min at 2100°C. Addition of B4C leads to an increase in the density sample from 76 to 97%. B4C nano-powder resists grain growth even at high temperature 2100°C. The formation of TaB2/carbon at TaC grain boundaries helps in pinning the grain boundary and inhibiting grain growth. The phase formation was associated with carbon and boron diffusion from the starting particles B4C to form TaB2 phases. TaC grain sizes decreased with increase in B4C concentration. Samples with 2.0 wt% B4C composition had highest flexure strength up to 520 MPa. The effect of B4C addition on hardness measured by microhardness has been studied. Hardness of samples containing 3.0 wt% B4C was 16.99 GPa.

  5. Validation of Satellite Derived Primary Production Models in the Northeast Atlantic

    Science.gov (United States)

    Lobanova, P. V.; Bashmachnikov, I. L.; Brotas, V.

    2016-08-01

    With all the variety of models used for calculation of primary production of phytoplankton (PP) from remote sensing data, a choice of the most realistic one for a particular ocean region remains a non-trivial issue. In this work, we estimate PP in the Northeast Atlantic Ocean (200 - 510 N and 100 - 400 W) from 1998 to 2005 using three frequently used models: VGPM (Vertically Generalized Production Model), PSM (Platt and Sathyendranath Model) and Aph-PP model (Absorption Based Model). The modeled results are then compared with in situ observations of PP. The results show a close similarity in PP patterns obtained by different models, but the absolute modeled values differ substantially. In the Northeast Atlantic, PSM is found reproducing better the observed seasonal and spatial variability of PP as compared to the two other models. However, PSM slightly underestimates the PP values.

  6. A Satellite-Derived Climatological Analysis of Urban Heat Island over Shanghai during 2000–2013

    Directory of Open Access Journals (Sweden)

    Weijiao Huang

    2017-06-01

    Full Text Available The urban heat island is generally conducted based on ground observations of air temperature and remotely sensing of land surface temperature (LST. Satellite remotely sensed LST has the advantages of global coverage and consistent periodicity, which overcomes the weakness of ground observations related to sparse distributions and costs. For human related studies and urban climatology, canopy layer urban heat island (CUHI based on air temperatures is extremely important. This study has employed remote sensing methodology to produce monthly CUHI climatology maps during the period 2000–2013, revealing the spatiotemporal characteristics of daytime and nighttime CUHI during this period of rapid urbanization in Shanghai. Using stepwise linear regression, daytime and nighttime air temperatures at the four overpass times of Terra/Aqua were estimated based on time series of Terra/Aqua-MODIS LST and other auxiliary variables including enhanced vegetation index, normalized difference water index, solar zenith angle and distance to coast. The validation results indicate that the models produced an accuracy of 1.6–2.6 °C RMSE for the four overpass times of Terra/Aqua. The models based on Terra LST showed higher accuracy than those based on Aqua LST, and nighttime air temperature estimation had higher accuracy than daytime. The seasonal analysis shows daytime CUHI is strongest in summer and weakest in winter, while nighttime CUHI is weakest in summer and strongest in autumn. The annual mean daytime CUHI during 2000–2013 is 1.0 and 2.2 °C for Terra and Aqua overpass, respectively. The annual mean nighttime CUHI is about 1.0 °C for both Terra and Aqua overpass. The resultant CUHI climatology maps provide a spatiotemporal quantification of CUHI with emphasis on temperature gradients. This study has provided information of relevance to urban planners and environmental managers for assessing and monitoring urban thermal environments which are constantly

  7. Changes in satellite-derived spring vegetation green-up date and its linkage to climate in China from 1982 to 2010: a multimethod analysis.

    Science.gov (United States)

    Cong, Nan; Wang, Tao; Nan, Huijuan; Ma, Yuecun; Wang, Xuhui; Myneni, Ranga B; Piao, Shilong

    2013-03-01

    The change in spring phenology is recognized to exert a major influence on carbon balance dynamics in temperate ecosystems. Over the past several decades, several studies focused on shifts in spring phenology; however, large uncertainties still exist, and one understudied source could be the method implemented in retrieving satellite-derived spring phenology. To account for this potential uncertainty, we conducted a multimethod investigation to quantify changes in vegetation green-up date from 1982 to 2010 over temperate China, and to characterize climatic controls on spring phenology. Over temperate China, the five methods estimated that the vegetation green-up onset date advanced, on average, at a rate of 1.3 ± 0.6 days per decade (ranging from 0.4 to 1.9 days per decade) over the last 29 years. Moreover, the sign of the trends in vegetation green-up date derived from the five methods were broadly consistent spatially and for different vegetation types, but with large differences in the magnitude of the trend. The large intermethod variance was notably observed in arid and semiarid vegetation types. Our results also showed that change in vegetation green-up date is more closely correlated with temperature than with precipitation. However, the temperature sensitivity of spring vegetation green-up date became higher as precipitation increased, implying that precipitation is an important regulator of the response of vegetation spring phenology to change in temperature. This intricate linkage between spring phenology and precipitation must be taken into account in current phenological models which are mostly driven by temperature. © 2012 Blackwell Publishing Ltd.

  8. Aerus-GEO: newly available satellite-derived aerosol optical depth product over Europe and Africa

    Science.gov (United States)

    Carrer, D.; Roujean, J. L.; Ceamanos, X.; Six, B.; Suman, S.

    2015-12-01

    The major difficulty in detecting the aerosol signal from visible and near-infrared remote sensing observations is to reach the proper separation of the components related to the atmosphere and the surface. A method is proposed to circumvent this issue by exploiting the directional and temporal dimensions of the satellite signal through the use of a semi-empirical kernel-driven model for the surface/atmosphere coupled system. This algorithm was implemented by the ICARE Data Center (http://www.icare.univ-lille1.fr), which operationally disseminates a daily AOD product at 670 nm over the MSG disk since 2014. The proposed method referred to as AERUS-GEO (Aerosol and surface albEdo Retrieval Using a directional Splitting method - application to GEO data) is applied to three spectral bands (0.6 mm, 0.8 mm, and 1.6 mm) of MSG (Meteosat Second Generation) observations, which scan Europe, Africa, and the Eastern part of South America every 15 minutes. The daily AOD estimates at 0.63μm has been extensively validated. In contrast, the Angstrom coefficient is still going through validation and we will show the differences between the MSG derived Angstrom exponent with that of CAMS (Copernicus Atmosphere Monitoring Service) near-real time aerosol product. The impact of aerosol type on the aerosol radiative forcing will be presented as a part of future development plan.

  9. Multi-site assimilation of a terrestrial biosphere model (BETHY) using satellite derived soil moisture data

    Science.gov (United States)

    Wu, Mousong; Sholze, Marko

    2017-04-01

    We investigated the importance of soil moisture data on assimilation of a terrestrial biosphere model (BETHY) for a long time period from 2010 to 2015. Totally, 101 parameters related to carbon turnover, soil respiration, as well as soil texture were selected for optimization within a carbon cycle data assimilation system (CCDAS). Soil moisture data from Soil Moisture and Ocean Salinity (SMOS) product was derived for 10 sites representing different plant function types (PFTs) as well as different climate zones. Uncertainty of SMOS soil moisture data was also estimated using triple collocation analysis (TCA) method by comparing with ASCAT dataset and BETHY forward simulation results. Assimilation of soil moisture to the system improved soil moisture as well as net primary productivity(NPP) and net ecosystem productivity (NEP) when compared with soil moisture derived from in-situ measurements and fluxnet datasets. Parameter uncertainties were largely reduced relatively to prior values. Using SMOS soil moisture data for assimilation of a terrestrial biosphere model proved to be an efficient approach in reducing uncertainty in ecosystem fluxes simulation. It could be further used in regional an global assimilation work to constrain carbon dioxide concentration simulation by combining with other sources of measurements.

  10. Validation of satellite derived LHF using coare_3.0 scheme and time series data over north-east Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Muraleedharan, P.M.; Pankajakshan, T.; Sathe, P.V.

    -6538 versión on-line Gayana (Concepc.) v.68 n.2 supl.TIIProc Concepción 2004 Como citar este artículo Gayana 68(2): 420-426, 2004 VALIDATION OF SATELLITE DERIVED LHF USING COARE_3.0 SCHEME AND TIME SERIES DATA OVER NORTH-EAST INDIAN...

  11. Improvements of Satellite-Derived Cyclonic Rainfall over the North Atlantic.

    Science.gov (United States)

    Klepp, Christian-Philipp; Bakan, Stephan; Graßl, Hartmut

    2003-02-01

    Case studies of rainfall, derived from Special Sensor Microwave Imager (SSM/I) satellite data during the passage of individual cyclones over the North Atlantic, are presented to enhance the knowledge of rainfall processes associated with frontal systems. A multisatellite method is applied for complete coverage of the North Atlantic twice a day. Different SSM/I precipitation algorithms have been tested for individual cyclones and compared to the Global Precipitation Climatology Project (GPCP) datasets. An independent rainfall pattern and intensity validation method is presented using voluntary observing ship (VOS) datasets and Advanced Very High Resolution Radiometer (AVHRR) images.Intense cyclones occur frequently in the wintertime period, with cold fronts propagating far south over the North Atlantic. Following upstream, large cloud clusters are frequently embedded in the cellular structured cold air of the backside regions, which produce heavy convective rainfall events, especially in the region off Newfoundland around 50°N. These storms can be easily identified on AVHRR images. It transpired that only the SSM/I rainfall algorithm of Bauer and Schlüssel is sensitive enough to detect the rainfall patterns and intensities observed by VOS for those cyclone types over the North Atlantic. In contrast, the GPCP products do not recognize this backside rainfall, whereas the frontal rainfall conditions are well represented in all tested datasets. This is suggested from the results of an intensive intercomparison study with ship reports from the time period of the Fronts and Atlantic Storm Track Experiment (FASTEX) field campaign. For this purpose, a new technique has been developed to transfer ship report codes into rain-rate estimates. From the analysis of a complete life cycle of a cyclone, it follows that these mesoscale backside rainfall events contribute up to 25% to the total amount of rainfall in North Atlantic cyclones.

  12. Management and climate contributions to satellite-derived active fire trends in the contiguous United States

    Science.gov (United States)

    Lin, Hsiao-Wen; McCarty, Jessica L.; Wang, Dongdong; Rogers, Brendan M.; Morton, Douglas C.; Collatz, G. James; Jin, Yufang; Randerson, James T.

    2014-04-01

    Fires in croplands, plantations, and rangelands contribute significantly to fire emissions in the United States, yet are often overshadowed by wildland fires in efforts to develop inventories or estimate responses to climate change. Here we quantified decadal trends, interannual variability, and seasonality of Terra Moderate Resolution Imaging Spectroradiometer (MODIS) observations of active fires (thermal anomalies) as a function of management type in the contiguous U.S. during 2001-2010. We used the Monitoring Trends in Burn Severity database to identify active fires within the perimeter of large wildland fires and land cover maps to identify active fires in croplands. A third class of fires defined as prescribed/other included all residual satellite active fire detections. Large wildland fires were the most variable of all three fire types and had no significant annual trend in the contiguous U.S. during 2001-2010. Active fires in croplands, in contrast, increased at a rate of 3.4% per year. Cropland and prescribed/other fire types combined were responsible for 77% of the total active fire detections within the U.S and were most abundant in the south and southeast. In the west, cropland active fires decreased at a rate of 5.9% per year, likely in response to intensive air quality policies. Potential evaporation was a dominant regulator of the interannual variability of large wildland fires, but had a weaker influence on the other two fire types. Our analysis suggests it may be possible to modify landscape fire emissions within the U.S. by influencing the way fires are used in managed ecosystems.

  13. Modelling dengue fever risk in the State of Yucatan, Mexico using regional-scale satellite-derived sea surface temperature.

    Science.gov (United States)

    Laureano-Rosario, Abdiel E; Garcia-Rejon, Julian E; Gomez-Carro, Salvador; Farfan-Ale, Jose A; Muller-Karger, Frank E

    2017-08-01

    Accurately predicting vector-borne diseases, such as dengue fever, is essential for communities worldwide. Changes in environmental parameters such as precipitation, air temperature, and humidity are known to influence dengue fever dynamics. Furthermore, previous studies have shown how oceanographic variables, such as El Niño Southern Oscillation (ENSO)-related sea surface temperature from the Pacific Ocean, influences dengue fever in the Americas. However, literature is lacking on the use of regional-scale satellite-derived sea surface temperature (SST) to assess its relationship with dengue fever in coastal areas. Data on confirmed dengue cases, demographics, precipitation, and air temperature were collected. Incidence of weekly dengue cases was examined. Stepwise multiple regression analyses (AIC model selection) were used to assess which environmental variables best explained increased dengue incidence rates. SST, minimum air temperature, precipitation, and humidity substantially explained 42% of the observed variation (r(2)=0.42). Infectious diseases are characterized by the influence of past cases on current cases and results show that previous dengue cases alone explained 89% of the variation. Ordinary least-squares analyses showed a positive trend of 0.20±0.03°C in SST from 2006 to 2015. An important element of this study is to help develop strategic recommendations for public health officials in Mexico by providing a simple early warning capability for dengue incidence. Copyright © 2017 Elsevier B.V. All rights reserved.

  14. Assessing Disagreement and Tolerance of Misclassification of Satellite-derived Land Cover Products Used in WRF Model Applications

    Institute of Scientific and Technical Information of China (English)

    GAO Hao; JIA Gensuo

    2013-01-01

    As more satellite-derived land cover products used in the study of global change,especially climate modeling,assessing their quality has become vitally important.In this study,we developed a distance metric based on the parameters used in weather research and forecasting (WRF) to characterize the degree of disagreement among land cover products and to identify the tolerance for misclassification within the International Geosphere Biosphere Programme (IGBP) classification scheme.We determined the spatial degree of disagreement and then created maps of misclassification of Moderate Resolution Imaging Spectoradiometer (MODIS) products,and we calculated overall and class-specific accuracy and fuzzy agreement in a WRF model.Our results show a high level of agreement and high tolerance of misclassification in the WRF model between large-scale homogeneous landscapes,while a low level of agreement and tolerance of misclassification appeared in heterogeneous landscapes.The degree of disagreement varied significantly among seven regions of China.The class-specific accuracy and fuzzy agreement in MODIS Collection 4 and 5 products varied significantly.High accuracy and fuzzy agreement occurred in the following classes:water,grassland,cropland,and barren or sparsely vegetated.Misclassification mainly occurred among specific classes with similar plant functional types and low discriminative spectro-temporal signals.Some classes need to be improved further; the quality of MODIS land cover products across China still does not meet the common requirements of climate modeling.Our findings may have important implications for improving land surface parameterization for simulating climate and for better understanding the influence of the land cover change on climate.

  15. Assessment of Satellite-Derived Essential Climate Variables in the Terrestrial Domain: Overview and Status of the CEOS LPV Subgroup

    Science.gov (United States)

    Roman, M. O.

    2015-12-01

    The validation of satellite-derived terrestrial observations has perennially faced the challenge of finding a consistent set of in-situ measurements that can both cover a wide range of surface conditions and provide timely and traceable product accuracy and uncertainty information. The Committee on Earth Observation Satellites (CEOS), the space arm of the Group on Earth Observations (GEO), plays a key role in coordinating the land product validation process. The Land Product Validation (LPV) sub-group of the CEOS Working Group on Calibration and Validation (WGCV) aims to address the challenges associated with the validation of global land products. This paper will provide a status of LPV subgroup focus area activities, which cover seven Global Climate Observing System (GCOS) terrestrial Essential Climate Variables (ECVs): (1) Snow Cover, (2) Surface Albedo, (3) Land Cover, (4) Leaf Area Index, (5) Fraction of Absorbed Photosynthetically Active Radiation (FAPAR), (6) Active Fires, and (7) Soil Moisture; as well as two additional variables (Land Surface Phenology and Land Surface Temperature), which are deemed of high priority of the LPV community. A primary focus of LPV is the implementation of a global validation framework for product intercomparison and validation (fig. 1). This framework is based on a citable protocol, fiducial reference data, and automated subsetting. Ideally, each of these parts will be integrated into an online platform where quantitative tests are run, and standardized intercomparison and validation results reported for all products used in the validation exercise. The establishment of consensus guidelines for in situ measurements as well as inter-comparison of trends derived from independently-obtained reference data and derived products will enhance coordination of the scientific needs of the Earth system communities with global LPV activities (http://lpvs.gsfc.nasa.gov/).

  16. Principle and geomorphological applicability of summit level and base level technique using Aster Gdem satellite-derived data and the original software Baz

    OpenAIRE

    Akihisa Motoki; Kenji Freire Motoki; Susanna Eleonora Sichel; Samuel da Silva; José Ribeiro Aires

    2015-01-01

    This article presents principle and geomorphological applicability of summit level technique using Aster Gdem satellite-derived topographicdata. Summit level corresponds to thevirtualtopographic surface constituted bylocalhighest points, such as peaks and plateau tops, and reconstitutes palaeo-geomorphology before the drainage erosion. Summit level map is efficient for reconstitution of palaeo-surfaces and detection of active tectonic movement. Base level is thevirtualsurface composed oflocal...

  17. Prognostic land surface albedo from a dynamic global vegetation model clumped canopy radiative transfer scheme and satellite-derived geographic forest heights

    Science.gov (United States)

    Kiang, N. Y.; Yang, W.; Ni-Meister, W.; Aleinov, I. D.; Jonas, J.

    2014-12-01

    Vegetation cover was introduced into general circulations models (GCMs) in the 1980's to account for the effect of land surface albedo and water vapor conductance on the Earth's climate. Schemes assigning canopy albedoes by broad biome type have been superceded in 1990's by canopy radiative transfer schemes for homogeneous canopies obeying Beer's Law extinction as a function of leaf area index (LAI). Leaf albedo and often canopy height are prescribed by plant functional type (PFT). It is recognized that this approach does not effectively describe geographic variation in the radiative transfer of vegetated cover, particularly for mixed and sparse canopies. GCM-coupled dynamic global vegetation models (DGVMs) have retained these simple canopy representations, with little further evaluation of their albedos. With the emergence lidar-derived canopy vertical structure data, DGVM modelers are now revisiting albedo simulation. We present preliminary prognostic global land surface albedo produced by the Ent Terrestrial Biosphere Model (TBM), a DGVM coupled to the NASA Goddard Institute for Space Studies (GISS) GCM. The Ent TBM is a next generation DGVM designed to incorporate variation in canopy heights, and mixed and sparse canopies. For such dynamically varying canopy structure, it uses the Analytical Clumped Two-Stream (ACTS) canopy radiative transfer model, which is derived from gap probability theory for canopies of tree cohorts with ellipsoidal crowns, and accounts for soil, snow, and bare stems. We have developed a first-order global vegetation structure data set (GVSD), which gives a year of satellite-derived geographic variation in canopy height, maximum canopy leaf area, and seasonal LAI. Combined with Ent allometric relations, this data set provides population density and foliage clumping within crowns. We compare the Ent prognostic albedoes to those of the previous GISS GCM scheme, and to satellite estimates. The impact of albedo differences on surface

  18. A New Temperature-Vegetation Triangle Algorithm with Variable Edges (TAVE for Satellite-Based Actual Evapotranspiration Estimation

    Directory of Open Access Journals (Sweden)

    Hua Zhang

    2016-09-01

    Full Text Available The estimation of spatially-variable actual evapotranspiration (AET is a critical challenge to regional water resources management. We propose a new remote sensing method, the Triangle Algorithm with Variable Edges (TAVE, to generate daily AET estimates based on satellite-derived land surface temperature and the vegetation index NDVI. The TAVE captures heterogeneity in AET across elevation zones and permits variability in determining local values of wet and dry end-member classes (known as edges. Compared to traditional triangle methods, TAVE introduces three unique features: (i the discretization of the domain as overlapping elevation zones; (ii a variable wet edge that is a function of elevation zone; and (iii variable values of a combined-effect parameter (that accounts for aerodynamic and surface resistance, vapor pressure gradient, and soil moisture availability along both wet and dry edges. With these features, TAVE effectively addresses the combined influence of terrain and water stress on semi-arid environment AET estimates. We demonstrate the effectiveness of this method in one of the driest countries in the world—Jordan, and compare it to a traditional triangle method (TA and a global AET product (MOD16 over different land use types. In irrigated agricultural lands, TAVE matched the results of the single crop coefficient model (−3%, in contrast to substantial overestimation by TA (+234% and underestimation by MOD16 (−50%. In forested (non-irrigated, water consuming regions, TA and MOD16 produced AET average deviations 15.5 times and −3.5 times of those based on TAVE. As TAVE has a simple structure and low data requirements, it provides an efficient means to satisfy the increasing need for evapotranspiration estimation in data-scarce semi-arid regions. This study constitutes a much needed step towards the satellite-based quantification of agricultural water consumption in Jordan.

  19. Satellite Derived Water Quality Observations Are Related to River Discharge and Nitrogen Loads in Pensacola Bay, Florida

    Directory of Open Access Journals (Sweden)

    John C. Lehrter

    2017-09-01

    Full Text Available Relationships between satellite-derived water quality variables and river discharges, concentrations and loads of nutrients, organic carbon, and sediments were investigated over a 9-year period (2003–2011 in Pensacola Bay, Florida, USA. These analyses were conducted to better understand which river forcing factors were the primary drivers of estuarine variability in several water quality variables. Remote sensing reflectance time-series data were retrieved from the MEdium Resolution Imaging Spectrometer (MERIS and used to calculate monthly and annual estuarine time-series of chlorophyll a (Chla, colored dissolved organic matter (CDOM, and total suspended sediments (TSS. Monthly MERIS Chla varied from 2.0 mg m−3 in the lower region of the bay to 17.2 mg m−3 in the upper bay. MERIS CDOM and TSS exhibited similar patterns with ranges of 0.51–2.67 (m−1 and 0.11–8.9 (g m−3. Variations in the MERIS-derived monthly and annual Chla, CDOM, and TSS time-series were significantly related to monthly and annual river discharge and loads of nitrogen, organic carbon, and suspended sediments from the Escambia and Yellow rivers. Multiple regression models based on river loads (independent variables and MERIS Chla, CDOM, or TSS (dependent variables explained significant fractions of the variability (up to 62% at monthly and annual scales. The most significant independent variables in the regressions were river nitrogen loads, which were associated with increased MERIS Chla, CDOM, and TSS concentrations, and river suspended sediment loads, which were associated with decreased concentrations. In contrast, MERIS water quality variations were not significantly related to river total phosphorus loads. The spatially synoptic, nine-year satellite record expanded upon the spatial extent of past field studies to reveal previously unseen system-wide responses to river discharge and loading variation. The results indicated that variations in Pensacola Bay Chla

  20. Dead Layer in a Ta/Ni81Fe19/Ta Structure

    Institute of Scientific and Technical Information of China (English)

    于广华; 任婷婷; 李明华; 朱逢吾; 姜宏伟; 赖武彦

    2002-01-01

    The effect of Ta seed layers and Ta cap layers on the effective magnetic thickness of ultrathin permalloy (Ni81 Fe19)was experimentally investigated for magnetic random access memory applications. The films were deposited by magnetron sputtering. For a Ta/Ni81Fe19/Ta fundamental structure, the Ta seed and Ta cap layers resulted in a loss of moment equivalent to a magnetically dead layer of thickness 1.6 ± 0.2 nm. In order to find the mechanism, the composition and chemical states at the interface regions of Ta/Ni81 Fe19 and Ni81 Fe19/Ta were studied using x-ray photoelectron spectroscopy and the peak decomposition technique. The results show that there are thermodynamically favourable reactions at the Ta/Ni81 Fe19 and Ni81Fe19/Ta interfaces: 2Ta + Ni = NiTa2.

  1. Evaluation of the ISBA-TRIP continental hydrologic system over the Niger basin using in situ and satellite derived datasets

    Science.gov (United States)

    Pedinotti, V.; Boone, A.; Decharme, B.; Crétaux, J. F.; Mognard, N.; Panthou, G.; Papa, F.; Tanimoun, B. A.

    2012-06-01

    During the 1970s and 1980s, West Africa has faced extreme climate variations with extended drought conditions. Of particular importance is the Niger basin, since it traverses a large part of the Sahel and is thus a critical source of water for an ever-increasing local population in this semi arid region. However, the understanding of the hydrological processes over this basin is currently limited by the lack of spatially distributed surface water and discharge measurements. The purpose of this study is to evaluate the ability of the ISBA-TRIP continental hydrologic system to represent key processes related to the hydrological cycle of the Niger basin. ISBA-TRIP is currently used within a coupled global climate model, so that the scheme must represent the first order processes which are critical for representing the water cycle while retaining a limited number of parameters and a simple representation of the physics. To this end, the scheme uses first-order approximations to account explicitly for the surface river routing, the floodplain dynamics, and the water storage using a deep aquifer reservoir. In the current study, simulations are done at a 0.5 by 0.5° spatial resolution over the 2002-2007 period (in order to take advantage of the recent satellite record and data from the African Monsoon Multidisciplinary Analyses project, AMMA). Four configurations of the model are compared to evaluate the separate impacts of the flooding scheme and the aquifer on the water cycle. Moreover, the model is forced by two different rainfall datasets to consider the sensitivity of the model to rainfall input uncertainties. The model is evaluated using in situ discharge measurements as well as satellite derived flood extent, total continental water storage changes and river height changes. The basic analysis of in situ discharges confirms the impact of the inner delta area, known as a significant flooded area, on the discharge, characterized by a strong reduction of the

  2. Evaluation of the ISBA-TRIP continental hydrologic system over the Niger basin using in situ and satellite derived datasets

    Directory of Open Access Journals (Sweden)

    V. Pedinotti

    2012-06-01

    Full Text Available During the 1970s and 1980s, West Africa has faced extreme climate variations with extended drought conditions. Of particular importance is the Niger basin, since it traverses a large part of the Sahel and is thus a critical source of water for an ever-increasing local population in this semi arid region. However, the understanding of the hydrological processes over this basin is currently limited by the lack of spatially distributed surface water and discharge measurements. The purpose of this study is to evaluate the ability of the ISBA-TRIP continental hydrologic system to represent key processes related to the hydrological cycle of the Niger basin. ISBA-TRIP is currently used within a coupled global climate model, so that the scheme must represent the first order processes which are critical for representing the water cycle while retaining a limited number of parameters and a simple representation of the physics. To this end, the scheme uses first-order approximations to account explicitly for the surface river routing, the floodplain dynamics, and the water storage using a deep aquifer reservoir. In the current study, simulations are done at a 0.5 by 0.5° spatial resolution over the 2002–2007 period (in order to take advantage of the recent satellite record and data from the African Monsoon Multidisciplinary Analyses project, AMMA. Four configurations of the model are compared to evaluate the separate impacts of the flooding scheme and the aquifer on the water cycle. Moreover, the model is forced by two different rainfall datasets to consider the sensitivity of the model to rainfall input uncertainties. The model is evaluated using in situ discharge measurements as well as satellite derived flood extent, total continental water storage changes and river height changes. The basic analysis of in situ discharges confirms the impact of the inner delta area, known as a significant flooded area, on the discharge, characterized by a strong

  3. "TA-DA!"

    DEFF Research Database (Denmark)

    Nielsen, Andreas Højlund; Gebauer, Line; Mcgregor, William

    participants’ (n = 17) mismatch fields (magnetic equivalent of the MMR). We found a main effect of contrast direction (pFWE=0.001 at the cluster-level), peaking around 124 ms after deviance onset. Contrast estimates revealed that this main effect was driven by stronger MMRs to both [tæ] and [æt] than to [dæ......] and [æd]. Participants’ brains thus seem to experience the perceptual distance from [d] to [t] as larger than that from [t] to [d], despite the acoustic difference being the same for both contrasts. We discuss this finding in relation to previous studies on asymmetries in speech perception, as well...

  4. Observation of 186mTa

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Unreported tantalum isomer 18mTa has been produced through the reaction 186W(n,p) by irradiation of natW with 14 MeV neutrons. The activity of 186Ta and 186Ta was measured using HPGe detectors and several X-γ as well as γ-γ coincidence arrangements. The 186mTa has been identified by means of measuring known γ rays from 186Ta p-decay. The half-life of 186mTa has been determined to be (1.5±0.1) min.

  5. Validation of satellite-derived tropical cyclone heat potential with in situ observations in the North Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Nagamani, P.V.; Ali, M.M.; Goni, G.J.; Dinezio, P.N.; Pezzullo, J.C.; UdayaBhaskar, T.V.S.; Gopalakrishna, V.V.; Nisha, K.

    , there is a need for satellite-based estimations. One potential solution is to use sea surface height anomalies (SSHAs) from altimeter observations. However, any estimation derived from satellite measurements requires extensive regional validation...

  6. Evaluation of Excitation Function for 182Ta

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    <正>Present work concerns the evaluated neutron induced excitation function data for 182Ta, and mainly on (n, γ) reaction channel. The related experimental data were collected, analyzed and corrected for 182Ta

  7. How robust are in situ observations for validating satellite-derived albedo over the dark zone of the Greenland Ice Sheet?

    Science.gov (United States)

    Ryan, J. C.; Hubbard, A.; Irvine-Fynn, T. D.; Doyle, S. H.; Cook, J. M.; Stibal, M.; Box, J. E.

    2017-06-01

    Calibration and validation of satellite-derived ice sheet albedo data require high-quality, in situ measurements commonly acquired by up and down facing pyranometers mounted on automated weather stations (AWS). However, direct comparison between ground and satellite-derived albedo can only be justified when the measured surface is homogeneous at the length-scale of both satellite pixel and in situ footprint. Here we use digital imagery acquired by an unmanned aerial vehicle to evaluate point-to-pixel albedo comparisons across the western, ablating margin of the Greenland Ice Sheet. Our results reveal that in situ measurements overestimate albedo by up to 0.10 at the end of the melt season because the ground footprints of AWS-mounted pyranometers are insufficient to capture the spatial heterogeneity of the ice surface as it progressively ablates and darkens. Statistical analysis of 21 AWS across the entire Greenland Ice Sheet reveals that almost half suffer from this bias, including some AWS located within the wet snow zone.

  8. Main: 1TA3 [RPSD[Archive

    Lifescience Database Archive (English)

    Full Text Available 1TA3 小麦 Bread Wheat Triticum aestivum Xylanase Inhibitor Protein I Precursor. Name=...479.1; -.|PDB; 1OM0; X-ray; A=31-304.|PDB; 1TA3; X-ray; A=-.|PDB; 1TE1; X-ray; A=...CGYPPAAHVGRALATGIFERAHVRTYESDKWCNQNLGWEGSWDKWTAAYPATRFYVGLTADDKSHQWVHPKNVYYGVAPVAQKKDNYGGIMLWDRYFDKQTNYSSLIKYYA wheat_1TA3.jpg ...

  9. Retention Model of TaO/HfO x and TaO/AlO x RRAM with Self-Rectifying Switch Characteristics

    Science.gov (United States)

    Lin, Yu-De; Chen, Pang-Shiu; Lee, Heng-Yuan; Chen, Yu-Sheng; Rahaman, Sk. Ziaur; Tsai, Kan-Hsueh; Hsu, Chien-Hua; Chen, Wei-Su; Wang, Pei-Hua; King, Ya-Chin; Lin, Chrong Jung

    2017-06-01

    A retention behavior model for self-rectifying TaO/HfO x - and TaO/AlO x -based resistive random-access memory (RRAM) is proposed. Trapping-type RRAM can have a high resistance state (HRS) and a low resistance state (LRS); the degradation in a LRS is usually more severe than that in a HRS, because the LRS during the SET process is limited by the internal resistor layer. However, if TaO/AlO x elements are stacked in layers, the LRS retention can be improved. The LRS retention time estimated by extrapolation method is more than 5 years at room temperature. Both TaO/HfO x - and TaO/AlO x -based RRAM structures have the same capping layer of TaO, and the activation energy levels of both types of structures are 0.38 eV. Moreover, the additional AlO x switching layer of a TaO/AlO x structure creates a higher O diffusion barrier that can substantially enhance retention, and the TaO/AlO x structure also shows a quite stable LRS under biased conditions.

  10. Mediating states in 180Ta

    OpenAIRE

    Alexa, Petr

    2002-01-01

    Possible theoretical electromagnetic paths between the ground state and the isomeric state at 75.3 keV in 180Ta are discussed in the framework of the two-quasiparticle-plus-phonon model and the standard axially-symmetric rotor model including Coriolis mixing. Experimental transition rates from the isomeric state to the ground state via observed mediating states are compared to the theoretical ones.

  11. Predicting bird phenology from space: satellite-derived vegetation green-up signal uncovers spatial variation in phenological synchrony between birds and their environment.

    Science.gov (United States)

    Cole, Ella F; Long, Peter R; Zelazowski, Przemyslaw; Szulkin, Marta; Sheldon, Ben C

    2015-11-01

    Population-level studies of how tit species (Parus spp.) track the changing phenology of their caterpillar food source have provided a model system allowing inference into how populations can adjust to changing climates, but are often limited because they implicitly assume all individuals experience similar environments. Ecologists are increasingly using satellite-derived data to quantify aspects of animals' environments, but so far studies examining phenology have generally done so at large spatial scales. Considering the scale at which individuals experience their environment is likely to be key if we are to understand the ecological and evolutionary processes acting on reproductive phenology within populations. Here, we use time series of satellite images, with a resolution of 240 m, to quantify spatial variation in vegetation green-up for a 385-ha mixed-deciduous woodland. Using data spanning 13 years, we demonstrate that annual population-level measures of the timing of peak abundance of winter moth larvae (Operophtera brumata) and the timing of egg laying in great tits (Parus major) and blue tits (Cyanistes caeruleus) is related to satellite-derived spring vegetation phenology. We go on to show that timing of local vegetation green-up significantly explained individual differences in tit reproductive phenology within the population, and that the degree of synchrony between bird and vegetation phenology showed marked spatial variation across the woodland. Areas of high oak tree (Quercus robur) and hazel (Corylus avellana) density showed the strongest match between remote-sensed vegetation phenology and reproductive phenology in both species. Marked within-population variation in the extent to which phenology of different trophic levels match suggests that more attention should be given to small-scale processes when exploring the causes and consequences of phenological matching. We discuss how use of remotely sensed data to study within-population variation

  12. Satellite-derived surface and sub-surface water storage in the Ganges–Brahmaputra River Basin

    Directory of Open Access Journals (Sweden)

    Fabrice Papa

    2015-09-01

    New hydrological insights: Basin-scale monthly SWS variations for the period 2003–2007 show a mean annual amplitude of ∼410 km3, contributing to about 45% of the Gravity Recovery And Climate Experiment (GRACE-derived total water storage variations (TWS. During the drought-like conditions in 2006, we estimate that the SWS deficit over the entire GB basin in July–August–September was about 30% as compared to other years. The SWS variations are then used to decompose the GB GRACE-derived TWS and isolate the variations of SSWS whose mean annual amplitude is estimated to be ∼550 km3. This new dataset of water storage variations represent an unprecedented source of information for hydrological and climate modeling studies of the ISC.

  13. Satellite-derived geoid for the estimation of lithospheric cooling and basal heat flux anomalies over the northern Indian Ocean lithosphere

    Indian Academy of Sciences (India)

    S Rajesh; T J Majumdar

    2015-12-01

    The northern Indian Ocean consists of older Bay of Bengal (BOB) oceanic lithosphere with numerous intra-plate loads; whereas, contrasting elements like active Mid-Ocean ridge divergence and slow spreading ridges are present in the relatively younger (<60 Ma) Arabian Sea oceanic lithosphere. The mechanism of lithospheric cooling of young age oceanic lithosphere from the moderately active and slow spreading Carlsberg Ridge is analysed by considering the hypothesis of near lithospheric convective action or whole upper mantle convection. We addressed these issues by studying the marine geoid at different spatial wavelengths and retrieved and compared their lithospheric cooling signatures, plate spreading and distribution of mass and heat anomalies along with seismicity, bathymetry, gravity and isochron age data. Results show that progressive cooling of young-aged oceanic lithosphere from the Mid-Ocean Carlsberg Ridge is because of conductive cooling and those signals are retrieved in the shorter wavelength band (111 < < 1900 km) of constrained residual geoid with mass anomaly sources near to sublithospheric. This shows steadiness in the geoid anomaly decay rate (∼–0.1 m/Ma), consistency in the growth of thermal boundary layer and progressive fall of basal temperature and heat flux (900–300 K and 100–18 mW m−2) with increase of lithospheric age. The above observations are attributed to the fact that the advective–convective action beneath the Mid-Ocean Carlsberg Ridge is driven by the basal temperature gradient between the lithosphere and the near lithospheric low viscose thin layer. But, for the case of old-aged oceanic lithosphere in the BOB, the residual geoid anomaly cooling signals are not prominently seen in the same band as that of the Arabian Sea because of the Ninetyeast Ridge magmatism. However, its cooling anomaly signatures are retrieved at relatively higher band (1335 ≤ ≤ 3081 km) having erratic geoid decay rates (–0.3 to 0.2 m/Ma) owing to vigorous convective thermal instabilities originated around 290–530 km from the plume remnant in the upper mantle (for the case of the BOB). We discussed that such instabilities had transported sufficient heat energy to accelerate the erstwhile fast movement of the Indian Plate prior to the India–Eurasia continent–continent collision.

  14. 78 FR 28627 - TA-W-80,340; TA-W-80,340A; TA-W-80,340B

    Science.gov (United States)

    2013-05-15

    ... Employment and Training Administration TA-W-80,340; TA-W-80,340A; TA-W-80,340B] Bush Industries, Inc., Mason... (TA-W-80,340) and Bush Industries, Inc., Allen Street Facility, Jamestown, New York (TA-W- 80,340A... the subject firm's Erie, Pennsylvania facility. The amended notice applicable to TA-W-80,340 is...

  15. Sampling errors for satellite-derived tropical rainfall - Monte Carlo study using a space-time stochastic model

    Science.gov (United States)

    Bell, Thomas L.; Abdullah, A.; Martin, Russell L.; North, Gerald R.

    1990-01-01

    Estimates of monthly average rainfall based on satellite observations from a low earth orbit will differ from the true monthly average because the satellite observes a given area only intermittently. This sampling error inherent in satellite monitoring of rainfall would occur even if the satellite instruments could measure rainfall perfectly. The size of this error is estimated for a satellite system being studied at NASA, the Tropical Rainfall Measuring Mission (TRMM). First, the statistical description of rainfall on scales from 1 to 1000 km is examined in detail, based on rainfall data from the Global Atmospheric Research Project Atlantic Tropical Experiment (GATE). A TRMM-like satellite is flown over a two-dimensional time-evolving simulation of rainfall using a stochastic model with statistics tuned to agree with GATE statistics. The distribution of sampling errors found from many months of simulated observations is found to be nearly normal, even though the distribution of area-averaged rainfall is far from normal. For a range of orbits likely to be employed in TRMM, sampling error is found to be less than 10 percent of the mean for rainfall averaged over a 500 x 500 sq km area.

  16. Proton stopping in C+C, d+C, C+Ta and d+Ta collisions at 4.2A GeV/c

    CERN Document Server

    Simic, L; Simic, Lj.

    1998-01-01

    The shape of proton rapidity distributions is analysed in terms of their Gaussian components, and the average rapidity loss is determined in order to estimate the amount of stopping in C+C, d+C, C+Ta and d+Ta collisions at 4.2A GeV/c. Three Gaussians correspond to the nuclear transparency and describe well all peripheral and also C+C central collisions. Two-component shape is obtained in case of d+C and C+Ta central collisions. Finally one Gaussian, found in d+Ta central collisions, corresponds to the full stopping. The calculated values of the average rapidity loss support the qualitative relationship between the number of Gaussian components and the corresponding stopping power. It is also observed, in central collisions, that the average rapidity loss increases with the ratio of the number of target and the number of projectile participants.

  17. TA-55 and Sigma Overview

    Energy Technology Data Exchange (ETDEWEB)

    Spearing, Dane Robert [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Safeguards Science and Technology Group (NEN-1)

    2016-11-29

    These are slides from a facility overview presentation for visiting agencies to Los Alamos National Laboratory (LANL). The TA-55 Plutonium Facility (PF-4) is discussed in detail. PF-4 is a unique resource for US plutonium programs. The basic design is flexible and has adapted to changing national needs. It is a robust facility with strong safety and security implementation. It supports a variety of national programs. It will continue for many years into the future. Sigma is then discussed in detail, which handles everything from hydrogen to uranium. It has been in long term service to the Nation (nearly 60 years). It has a flexible authorization basis to handle almost the entire periodic table. It has a wide breadth of prototyping and characterization capabilities. It has integrated program and line management.

  18. Satellite-Derived Photic Depth on the Great Barrier Reef: Spatio-Temporal Patterns of Water Clarity

    Directory of Open Access Journals (Sweden)

    Scarla Weeks

    2012-11-01

    Full Text Available Detecting changes to the transparency of the water column is critical for understanding the responses of marine organisms, such as corals, to light availability. Long-term patterns in water transparency determine geographical and depth distributions, while acute reductions cause short-term stress, potentially mortality and may increase the organisms’ vulnerability to other environmental stressors. Here, we investigated the optimal, operational algorithm for light attenuation through the water column across the scale of the Great Barrier Reef (GBR, Australia. We implemented and tested a quasi-analytical algorithm to determine the photic depth in GBR waters and matched regional Secchi depth (ZSD data to MODIS-Aqua (2002–2010 and SeaWiFS (1997–2010 satellite data. The results of the in situ ZSD/satellite data matchup showed a simple bias offset between the in situ and satellite retrievals. Using a Type II linear regression of log-transformed satellite and in situ data, we estimated ZSD and implemented the validated ZSD algorithm to generate a decadal satellite time series (2002–2012 for the GBR. Water clarity varied significantly in space and time. Seasonal effects were distinct, with lower values during the austral summer, most likely due to river runoff and increased vertical mixing, and a decline in water clarity between 2008–2012, reflecting a prevailing La Niña weather pattern. The decline in water clarity was most pronounced in the inshore area, where a significant decrease in mean inner shelf ZSD of 2.1 m (from 8.3 m to 6.2 m occurred over the decade. Empirical Orthogonal Function Analysis determined the dominance of Mode 1 (51.3%, with the greatest variation in water clarity along the mid-shelf, reflecting the strong influence of oceanic intrusions on the spatio-temporal patterns of water clarity. The newly developed photic depth product has many potential applications for the GBR from water quality monitoring to analyses of

  19. Ammonia emissions in tropical biomass burning regions: Comparison between satellite-derived emissions and bottom-up fire inventories

    Science.gov (United States)

    Whitburn, S.; Van Damme, M.; Kaiser, J. W.; van der Werf, G. R.; Turquety, S.; Hurtmans, D.; Clarisse, L.; Clerbaux, C.; Coheur, P.-F.

    2015-11-01

    Vegetation fires emit large amounts of nitrogen compounds in the atmosphere, including ammonia (NH3). These emissions are still subject to large uncertainties. In this study, we analyze time series of monthly NH3 total columns (molec cm-2) from the IASI sounder on board MetOp-A satellite and their relation with MODIS fire radiative power (MW) measurements. We derive monthly NH3 emissions estimates for four regions accounting for a major part of the total area affected by fires (two in Africa, one in central South America and one in Southeast Asia), using a simplified box model, and we compare them to the emissions from both the GFEDv3.1 and GFASv1.0 biomass burning emission inventories. In order to strengthen the analysis, we perform a similar comparison for carbon monoxide (CO), also measured by IASI and for which the emission factors used in the inventories to convert biomass burned to trace gas emissions are thought to be more reliable. In general, a good correspondence between NH3 and CO columns and the FRP is found, especially for regions in central South America with correlation coefficients of 0.82 and 0.66, respectively. The comparison with the two biomass burning emission inventories GFASv1.0 and GFEDv3.1 shows good agreements, particularly in the time of the maximum of emissions for the central South America region and in the magnitude for the region of Africa south of the equator. We find evidence of significant non-pyrogenic emissions for the regions of Africa north of the equator (for NH3) and Southeast Asia (for NH3 and CO). On a yearly basis, total emissions calculated from IASI measurements for the four regions reproduce fairly well the interannual variability from the GFEDv3.1 and GFASv1.0 emissions inventories for NH3 but show values about 1.5-2 times higher than emissions given by the two biomass burning emission inventories, even when assuming a fairly long lifetime of 36 h for that species.

  20. Stoichiometry behavior of TaN, TaCN and TaC thin films produced by magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Vargas, M. [Centro de Nanociencia y Nanotecnología, Universidad Nacional Autónoma de México, A.P. 2681, C.P. 22860, Ensenada, B.C. (Mexico); Castillo, H.A. [Centro de Enseñanza Técnica y Superior, CETYS Universidad, Campus Tijuana, Tijuana, B.C. (Mexico); Restrepo-Parra, E., E-mail: erestrepopa@unal.edu.co [Universidad Nacional de Colombia Sede Medellín Colombia, Facultad de Minas, Manizales (Colombia); De La Cruz, W. [Centro de Nanociencia y Nanotecnología, Universidad Nacional Autónoma de México, A.P. 2681, C.P. 22860, Ensenada, B.C. (Mexico)

    2013-08-15

    Thin films were synthesized in a magnetron sputtering system using a target of Ta with 99.99% purity and silicon substrates (1 1 1). The gases used for the film growth were (Ar + N{sub 2}), (Ar + CH{sub 4} + N{sub 2}) and (Ar + CH{sub 4}) mixtures for TaN, TaCN and TaC, respectively. The substrate temperature increased from room temperature to 500 °C. The chemical composition and bonding configuration were examined using X-ray photoelectron spectroscopy (XPS), revealing Ta-N, Ta-C-N, Ta-C and C-C bonds. Moreover, the crystallographic structure was analyzed using X-ray diffraction (XRD), indicating the presence of (1 1 1) and (2 0 0) planes belonging to a face-centered cubic structure. The stoichiometry variation dependence on the CH{sub 4} and N{sub 2} flow was analyzed, and the influence of the substrate temperature on the coatings was investigated. Finally, scanning electron microscopy (SEM) was used to determine the evolution on the grain formation in the coatings as the substrate temperature increased.

  1. Combined Aircraft and Satellite-Derived Storm Electric Current and Lightning Rates Measurements and Implications for the Global Electric Circuit

    Science.gov (United States)

    Mach, Douglas M.; Blakeslee, Richard J.; Bateman, Monte G.

    2010-01-01

    curve) to within 4% for all but two short periods of time. This excellent agreement with the Carnegie curve was obtained without any tuning or adjustment of the satellite or aircraft data. Given our data and assumptions, mean contributions to the global electric circuit are 0.7 kA (ocean) and 1.1 kA (land) from lightning-producing storms, and 0.22 kA (ocean) and 0.04 (land) from electrified shower clouds, resulting in a mean total conduction current estimate for the global electric circuit of 2.0 kA. Breaking the results down into mean storm counts reveals 1100 for land storms with lightning, 530 for ocean storms without lightning, 390 for ocean storms with lightning, and 330 for land storms without lightning.

  2. Scaling of flat band potential and dielectric constant as a function of Ta concentration in Ta-TiO2 epitaxial films

    Directory of Open Access Journals (Sweden)

    Y. L. Zhao

    2011-06-01

    Full Text Available Electrochemical impedance spectroscopy measurements of pulsed laser deposited single crystal anatase TiO2 thin films with various concentrations of Ta substituting for Ti were carried out. The qualities of the films were characterized by X-ray diffraction and Rutherford back scattering-channeling measurements. UV-visible measurements show a systematic increase of the bandgap with Ta incorporation. Corresponding Mott-Schottky plot was applied to obtain a continuous shift of the flat band potential with increasing free charge carrier (provided by Ta concentration. This was verified theoretically by ab initio calculation which shows that extra Ta d-electrons occupy Ti t2g orbital with increasing Ta concentration, thereby pushing up the Fermi level. The Mott-Schottky results were consistent when compared with Hall effect and temperature dependent resistivity measurements. From the measured deviation of carrier densities from Hall and Mott-Schottky measurements we have estimated the static dielectric constant of the TiO2 as a function of Ta incorporation, not possible from capacitive measurements.

  3. Principle and geomorphological applicability of summit level and base level technique using Aster Gdem satellite-derived data and the original software Baz

    Directory of Open Access Journals (Sweden)

    Akihisa Motoki

    2015-05-01

    Full Text Available This article presents principle and geomorphological applicability of summit level technique using Aster Gdem satellite-derived topographicdata. Summit level corresponds to thevirtualtopographic surface constituted bylocalhighest points, such as peaks and plateau tops, and reconstitutes palaeo-geomorphology before the drainage erosion. Summit level map is efficient for reconstitution of palaeo-surfaces and detection of active tectonic movement. Base level is thevirtualsurface composed oflocallowest points, as valley bottoms. The difference between summit level and base level is called relief amount. Thesevirtualmapsareconstructed by theoriginalsoftwareBaz. Themacroconcavity index, MCI, is calculated from summit level and relief amount maps. The volume-normalised three-dimensional concavity index, TCI, is calculated from hypsometric diagram. The massifs with high erosive resistance tend to have convex general form and low MCI and TCI. Those with low resistance have concave form and high MCI and TCI. The diagram of TCI vs. MCI permits to distinguish erosive characteristics of massifs according to their constituent rocks. The base level map for ocean bottom detects the basement tectonic uplift which occurred before the formation of the volcanic seamounts.

  4. Towards Calibration of Sentinel 3 Data: Validation of Satellite-Derived SST Against In Situ Coastal Observations of the Portuguese Marine Waters

    Science.gov (United States)

    Vicente, Ricardo; Esteves, Rita; Lamas, Luisa; Pinto, Jose Paulo; Almeida, Sara; de Azevedo, Eduardo; Correia, Cecilia; Reis, Francisco

    2016-08-01

    Validation of future Sentinel-3 SLSTR data in the Eastern Atlantic Ocean was analysed here through a comparison of satellite-derived STT against in situ mooring buoys observations.SSTskin retrieved from IR satellite radiometers on- board ERS 1-2, Envisat, and Aqua, and concurrent SSTbulk measured with 14 buoy thermistors located at 1m depth were used to assess the statistical relationships between these datasets, with 20038 match- ups spanning from 1996 to 2015.As expected, results showed consistency between SSTskin and SSTbulk, exhibiting a correlation coefficient on the order of 98 %. Biases of both (A)ATSR and MODIS for day-time suggest a warmer satellite skin retrieval of + 0.15o and + 0.06o, respectively. For the night-time dataset, biases of - 0.25o and - 0.17o for (A)A TSR and MODIS, respectively, indicate cooler skin retrievals and reveal an inversion of the upper ocean thermic gradient. The RMSE ´s found were 0.53o for (A)ATSR and 0.41o for MODIS datasets.

  5. A photogrammetric DEM of Greenland based on 1978-1987 aerial photos: validation and integration with laser altimetry and satellite-derived DEMs

    Science.gov (United States)

    Korsgaard, N. J.; Kjaer, K. H.; Nuth, C.; Khan, S. A.

    2014-12-01

    Here we present a DEM of Greenland covering all ice-free terrain and the margins of the GrIS and local glaciers and ice caps. The DEM is based on the 3534 photos used in the aero-triangulation which were recorded by the Danish Geodata Agency (then the Geodetic Institute) in survey campaigns spanning the period 1978-1987. The GrIS is covered tens of kilometers into the interior due to the large footprints of the photos (30 x 30 km) and control provided by the aero-triangulation. Thus, the data are ideal for providing information for analysis of ice marginal elevation change and also control for satellite-derived DEMs.The results of the validation, error assessments and predicted uncertainties are presented. We test the DEM using Airborne Topographic Mapper (IceBridge ATM) as reference data; evaluate the a posteriori covariance matrix from the aero-triangulation; and co-register DEM blocks of 50 x 50 km to ICESat laser altimetry in order to evaluate the coherency.We complement the aero-photogrammetric DEM with modern laser altimetry and DEMs derived from stereoscopic satellite imagery (AST14DMO) to examine the mass variability of the Northeast Greenland Ice Stream (NEGIS). Our analysis suggests that dynamically-induced mass loss started around 2003 and continued throughout 2014.

  6. Field investigations of soils at TA-19, TA-26, TA-73 and TA-0, SWMU aggregate 0-D and 016

    Energy Technology Data Exchange (ETDEWEB)

    McFadden, L.D. [Geoprofile, Inc., Albuquerque, NM (United States)

    1995-03-01

    Field based investigations of the general soil-geomorphic characteristics were carried out at TA-19, -26, -73, -0, Aggregate 0-D and -016 in order to provide information for utilization in ongoing and anticipated LANL ERP (Environmental Restoration Project) activities at these sites. These investigations show that soils exhibiting diverse morphologic character, varying ages, and relations to landforms characterize these sites. A review of recent and ongoing soils studies also shows that soil textural, chemical, and mineralogical characteristics may profoundly influence the migration and/or retardation of a variety of potential contaminants initially placed in direct contact with soils, or that encounter soils during subsurface percolation or discharge. Soil-geomorphic relations also provide important insights into recent site erosion, deposition or other surficial processes that must, be considered as part of environmental assessment of a given site and remediation; and, the planned geomorphic mapping activities at each site, as well as other associated activities (e.g, geophysical survey, site sampling) are accordingly appropriate and necessary with respect to identification of significant soil relations at each site. Specific and general recommendations in consideration of important findings regarding the possible impacts of soil development of the nature of contaminant behavior at various sites are provided to help guide sampling and analysis activities during ERP investigations outlined in the RFI Work Plan for Operational Unit-1071.

  7. Anisotropic properties of TaS2

    Institute of Scientific and Technical Information of China (English)

    Qiao Yan-Bin; Li Yan-Ling; Zhong Guo-Hua; Zeng Zhi; Qin Xiao-Ying

    2007-01-01

    The anisotropic properties of 1T- and 2H-TaS2 are investigated by the density functional theory within the framework of full-potential linearized augmented plane wave method. The band structures of 1T- and 2H-TaS2 exhibit anisotropic properties and the calculated electronic specific-heat coefficient γ of 2H-TaS2 accords well with the existing experimental value. The anisotropic frequency-dependent dielectric functions including the effect of the Drude term are analysed, where the εxx(ω) spectra corresponding to the electric field E perpendicular to the z axis show excellent agreement with the measured results except for the ε1xx(ω) of 1T-TaS2 below the energy level of 2.6 eV which is due to the lack of the enough CDW information for reference in our calculation. Furthermore, based on the values of optical effective mass ratio P of 1T and 2H phases it is found that the anisotropy in 2H-TaS2 is stronger than that in 1T-TaS2.

  8. The 181Ta Nuclear Quadrupole Interaction in the Charge Density Wave Phases of 1T-TaS2

    Science.gov (United States)

    Ganal, P.; Butz, T.; Lerf, A.; Naito, M.; Nishihara, H.

    1990-04-01

    With a high resolution time differential perturbed angular correlation spectrometer we investigated the nuclear quadrupole interaction of Ta in 1T-TaS2 . The results obtained for the commensurate charge density wave phase lead to a revised assignment of the previously observed 181Ta NQR resonances. Differences in the intracluster architecture of the 13-atom Star of David cluster between 1T-TaS2 and 1T-TaSe2 could be responsible for the metal to semiconductor transition which occurs in lT-TaS2 but not in lT-TaSe2 .

  9. Ta thickness-dependent perpendicular magnetic anisotropy features in Ta/CoFeB/MgO/W free layer stacks

    Energy Technology Data Exchange (ETDEWEB)

    Yang, SeungMo; Lee, JaBin; An, GwangGuk [Novel Functional Materials and Devices Lab, The Research Institute for Natural Science, Department of Physics, Hanyang University, Seoul 133-791 (Korea, Republic of); Kim, JaeHong [Division of Nano-Scale Semiconductor Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of); Chung, WooSeong [Nano Quantum Electronics Lab, Department of Electronics and Computer Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of); Hong, JinPyo, E-mail: jphong@hanyang.ac.kr [Novel Functional Materials and Devices Lab, The Research Institute for Natural Science, Department of Physics, Hanyang University, Seoul 133-791 (Korea, Republic of); Division of Nano-Scale Semiconductor Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of)

    2015-07-31

    We describe Ta underlayer thickness influence on thermal stability of perpendicular magnetic anisotropy in Ta/CoFeB/MgO/W stacks. It is believed that thermal stability based on Ta underlay is associated with thermally-activated Ta atom diffusion during annealing. The difference in Ta thickness-dependent diffusion behaviors was confirmed with X-ray photoelectron spectroscopy analysis. Along with a feasible Ta thickness model, our observations suggest that an appropriate seed layer choice is needed for high temperature annealing stability, a critical issue in the memory industry. - Highlights: • We observed changes in the diffusion behavior with regard to Ta seed layer thickness. • It was observed that a thinner Ta seed layer induced more annealing-stable features. • However, ultra-thin (0.75 nm) Ta shows unstable characteristics about the annealing process. • It was possibly due to a rugged interface of the Ta layer by the island growth process.

  10. Spin polarization effect for molecule Ta2

    Institute of Scientific and Technical Information of China (English)

    Xie An-Dong

    2006-01-01

    Density functional theory (DFT) (B3p86) has been used to optimize the structure of the molecule Taa- The result shows that the ground state of molecule Ta,2 is a 7- multiple state and its electronic configuration is 7∑+u which shows the spin polarization effect for molecule Ta2 of transition metal elements for the first time. Meanwhile, spin pollution has not been found because the wavefunction of the ground state does not mix with those of higher states. So, the fact that the ground state of molecule Ta2 is a 7-multiple state indicates a spin polarization effect of molecule Ta2 of the transition metal elements, i.e. there exist 6 parallel spin electrons and the non-conjugated electrons are greatest in number. These electrons occupy different space orbitals so that the energy of molecule Ta2 is minimized. It can be concluded that the effect of parallel spin of the molecule Ta2 is larger than the effect of the conjugated molecule, which is obviously related to the effect of d-electron delocalization. In addition, the Murrell-Sorbie potential functions with parameters for the ground state 7∑+u and other states of the molecule Ta2 are derived. The dissociation energy De, equilibrium bond length Re and vibration frequency ωe for the ground state of molecule Ta2 are 4.5513eV, 0.2433nm and 173.06cm-1, respectively. Its force constants f2,f3 and f4 are 1.5965×l02aJ·nm-2,-6.4722×l03aJ·nm-3 and 29.4851×04aJ·nm-4, respectively. Other spectroscopic data ωe χe, Be and αe for the ground state of Ta2 are 0.2078cm-1, 0.0315cm-1 and 0.7858×104 cm-1, respectively.

  11. Subsidence hazard and risk assessments for Mexico City: An interdisciplinary analysis of satellite-derived subsidence map (PSInSAR) and census data.

    Science.gov (United States)

    Solano Rojas, D. E.; Cabral-Cano, E.; Wdowinski, S.; Hernaández Espriú, A.; Falorni, G.; Bohane, A.

    2014-12-01

    The Mexico City Metropolitan Area is the largest urban center in the American continent, with 20.4 millions of inhabitants, representing 17.8% of the total population of the country. Over the past several decades Mexico City has been experienced rapid subsidence, up to ~370 mm/yr, caused by groundwater extraction. The subsidence rate is inhomogeneous, as it controlled by the local geology. Unconsolidated sediments tend to compact and induce rapid subsidence, whereas subsurface volcanic rocks are less prone to subsidence. Intensive faulting in the city has been observed in areas of differential deformation; in these areas buildings and infrastructure are highly damaged. Quantification of subsidence-induce damage is needed for establishing the magnitude of the phenomenon. Our study uses three data sources: a satellite-derived subsidence map, census information of population distribution for 2010, and information on buildings and infrastructure. The subsidence map was calculated from 29 SAR scene acquired by the Envisat satellite during the years 2003-2010 using the Persistent Scatterers Interferometry (PSI) method with the SqueeSAR algorithm. The information of the census of population comes from the National Institute of Statistics and Geography (INEGI), which also provides the information about infrastructure. We intersected the information from the three maps using a geographic information system (GIS), which cover an area of 1, 640 km2. As subsidence-induced damage occurs mainly in areas of differential subsidence, we based the GIS analysis on the subsidence gradients, rather than subsidence rates. In order to evaluate subsidence-induced faulting risk, we generated a risk matrix that worked as the main parameter to create a risk map. We then reclassified the urban area into 5 zones according to the related risk, with R0 for the lowest risk and R4 for the highest. Our counting showed that 350 km2 of the city is located in an urban area of high to very high risk

  12. Rutile is holding Nb and Ta in the mantle, negligible Nb and Ta in the core

    Science.gov (United States)

    McDonough, W. F.; Rudnick, R. L.

    2008-12-01

    Continental Crust has a significant depletion in Nb and Ta relative to La that has been attributed to convergent margin (arc) magmatism and greater retention of Nb and Ta in the mantle source. This depleted pattern is a consequence of the plotting order of elements, which has been established by the relative partitioning behavior of elements during MORB-OIB genesis. It is our hypothesis that rutile in subducting slabs or delaminated lower continental crust is the important phase causing Nb(Ta)-depletion in the continental crust, as well as lowering its Nb/Ta. Experimental studies reveal a range of Nb/Ta fractionation responses in residual rutile depending on temperature and phase relations(melting vs dehydration). Examples of rutile-bearing, refractory eclogites have been identified that serve as analog materials for residues of the continental crust. These rutiles have radiogenic Hf isotopes (Vervoort, unpubl. data), and thus are not recent precipitates from metasomatic melts, as has been recently suggested. What remains is to understand the total silicate Earth's mass balance. In this regard, it is worth noting that early Archean Barbarton komatiites possess chondritic La/Nb ratios, and Nb/Ta ~15, a value comparable to Allende CV3 chondrite. This observation is not consistent with the storage of Nb (or Ta) in the core and suggests that the silicate Earth controls the planetary budget of Nb and Ta. Constraints on the amount of Nb in the core must be evaluated by multi-element approaches, using ratios of refractory lithophile elements. Chondritic ratios for La/Nb and Nb/Ta are not defined simply as a single value with a restricted range and are not always constant, with examples of both negligible and distinct differences between groups of chondrites. The database for chondrites is still small for Nb and Ta.

  13. Wet ammonia Synthesis of Semiconducting N:Ta2O5, Ta3N5 and β-TaON Films for Photoanode Applications

    NARCIS (Netherlands)

    Dabirian, A.; Van 't Spijker, H.; Van der Krol, R.

    2012-01-01

    Tantalum oxynitride (β-TaON) is a promising photoanode material for photoelectrochemical water splitting. However, the synthesis of phase-pure β-TaON films is a challenging task. This paper describes a novel approach to achieve this by the controlled nitridation of Ta2O5 films under a flow of ammoni

  14. Thermally stable perpendicular magnetic anisotropy features of Ta/TaO{sub x}/Ta/CoFeB/MgO/W stacks via TaO{sub x} underlayer insertion

    Energy Technology Data Exchange (ETDEWEB)

    Yang, SeungMo; Lee, JaBin; An, GwangGuk [Novel Functional Materials and Devices Laboratory, Research Institute for Natural Science, Department of Physics, Hanyang University, Seoul 133-791 (Korea, Republic of); Kim, JaeHong [Division of Nano-Scale Semiconductor Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of); Chung, WooSeong [Nano Quantum Electronics Lab, Department of Electronics and Computer Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of); Hong, JinPyo, E-mail: jphong@hanyang.ac.kr [Novel Functional Materials and Devices Laboratory, Research Institute for Natural Science, Department of Physics, Hanyang University, Seoul 133-791 (Korea, Republic of); Division of Nano-Scale Semiconductor Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of)

    2014-09-21

    We report that a TaO{sub x} underlayer enhances the stability of perpendicular magnetic anisotropy (PMA) in TaO{sub x}/Ta/CoFeB/MgO stacks during annealing; control of oxygen content in the TaO{sub x} layer is critical. X-ray photoelectron spectroscopy observations revealed clear suppression of Ta atom diffusion towards the CoFeB/MgO interface or MgO regions. The TaO{sub x} underlayer possibly served as a diffusion sponge, permitting some thermally activated Ta atoms to impregnate the TaO{sub x} underlayer via a diffusion path, such as grain boundaries. We propose a possible mechanism for enhanced PMA stability based on diffusion of thermally activated Ta atoms.

  15. Intrabeam Scattering Studies at CesrTA

    CERN Document Server

    Fermilab; Peterson, DP; Rider, NT; Rubin, DL; Holtzapple, R; Campbell, R; Shanks, JP; Strohman, CR; Wang, S; Papaphilippou, Y

    2012-01-01

    Intrabeam scattering (IBS) dilutes the emittance of low energy, low emittance rings. Because CesrTA can be operated at low energies with low transverse emittances and high bunch intensity, it is well-suited for the study of IBS. Furthermore, CesrTA is instrumented for accurate beam size measurements in all three dimensions, providing the possibility of a complete determination of the intensity dependence of emittances. Measurements from dedicated IBS machine studies at different emittances, intensities, and species are presented. A model based on analytic IBS theories is developed and compared to the data.

  16. Engineering Mathematics Assessment Using "MapleTA"

    Science.gov (United States)

    Jones, Ian S.

    2008-01-01

    The assessment of degree level engineering mathematics students using the computer-aided assessment package MapleTA is discussed. Experience of academic and practical issues for both online coursework and examination assessments is presented, hopefully benefiting other academics in this novel area of activity. (Contains 6 figures and 1 table.)

  17. Miks ta nii teeb? / Kristiina Voolaid

    Index Scriptorium Estoniae

    Voolaid, Kristiina

    1999-01-01

    Kuidas mõtleb ruumikujundaja, kui ta valib vorme, värve, materjale ja esemeid? Sisearhitekt Kristiina Voolaid seletab oma mõtteid Kawe Plaza hoones asuvate Hüvitusfondi ja Werol Tehased kontorite ning noorele perekonnale sisustatud vanalinnakorteri näitel

  18. Miks ta nii teeb? / Kristiina Voolaid

    Index Scriptorium Estoniae

    Voolaid, Kristiina

    1999-01-01

    Kuidas mõtleb ruumikujundaja, kui ta valib vorme, värve, materjale ja esemeid? Sisearhitekt Kristiina Voolaid seletab oma mõtteid Kawe Plaza hoones asuvate Hüvitusfondi ja Werol Tehased kontorite ning noorele perekonnale sisustatud vanalinnakorteri näitel

  19. Roles of TaON and Ta(3)N(5) in the visible-Fenton-like degradation of atrazine.

    Science.gov (United States)

    Du, Yingxun; Zhao, Lu; Zhang, Yuanyuan

    2014-02-28

    In this study, the roles of TaON and Ta3N5 in the degradation of atrazine by the visible-Fenton-like system were examined in detail. The TaON and Ta3N5 samples prepared by the nitridation of Ta2O5 and characterized by XRD, DRS, BET and PL analyses. The results showed that the TaON sample had weaker absorption in the visible region but higher specific surface area than the Ta3N5 sample. The degradation rate of atrazine in visible-TaON-Fenton-like system was 2.64 times than that in visible-Ta3N5-Fenton-like system. Both Fe(2+) and H2O2 could be reduced by eCB (electrons in the conduction band) in TaON or Ta3N5, while atrazine could not be oxidized by hVB (holes in the valance band). OH is the active species for the degradation of atrazine in visible-TaON/Ta3N5-Fenton-like systems. Majority of OH originated from Fenton reaction. After Fe(3+) was reduced by eCB to Fe(2+), Fe(2+) reacted quickly with H2O2 to generate OH. In addition, by capturing eCB, a little of H2O2 was reduced to yield OH, which contributed a small fraction of atrazine degradation. Based on the experimental results, the roles of TaON and Ta3N5 in the visible-Fenton-like system were proposed. And the higher photocatalytic activity of TaON than Ta3N5 was suggested to be due to the higher separation efficiency of electrons and holes, which may be related to the larger specific surface area.

  20. Thermodynamics and elastic properties of Ta from first-principles calculations

    Institute of Scientific and Technical Information of China (English)

    Li Qiang; Huang Duo-Hui; Cao Qi-Long; Wang Fan-Hou; Cai Ling-Cang; Zhang Xiu-Lu; Jing Fu-Qian

    2012-01-01

    Within the framework of the quasiharmonic approximation,the thermodynamics and elastic properties of Ta,including phonon density of states (DOS),equation of state,linear thermal expansion coefficient,entropy,enthalpy,heat capacity,elastic constants,bulk modulus,shear modulus,Young's modulus,microhardness,and sound velocity,are studied using the first-principles projector-augmented wave method.The vibrational contribution to Helmholtz free energy is evaluated from the first-principles phonon DOS and the Debye model.The thermal electronic contribution to Helmholtz free energy is estimated from the integration over the electronic DOS.By comparing the experimental results with the calculation results from the first-principles and the Debye model,it is found that the thermodynamic properties of Ta are depicted well by the first-principles.The elastic properties of Ta from the first-principles are consistent with the available experimental data.

  1. Low temperature electroformation of TaOx-based resistive switching devices

    Directory of Open Access Journals (Sweden)

    Darshil K. Gala

    2016-01-01

    Full Text Available Transport characteristics of TiN/Ta/TaOx/TiN resistive-switching crossbar devices with amorphous TaOx functional layer have been investigated at cryogenic temperatures. Quasi-DC I-V characteristics at 10 K show a negative differential resistance region followed by a rapid transition to the non-volatile formed state. Accounting for Joule heating, the device temperature at the point of switching was estimated at 150 K. Measurements of transient resistance at low stage temperatures revealed an abrupt drop of resistance delayed by a characteristic incubation time after the leading edge of the voltage pulse. The incubation time was a strong function of applied voltage but did not depend on temperature between 10 K and 100 K. This implies a very low activation energy of the threshold switching process at low temperatures. Both of these observations argue against the involvement of oxygen vacancy motion at the onset of the forming process.

  2. "ta surnud sõbrad..." : [luuletused] / Caspar Tops

    Index Scriptorium Estoniae

    Tops, Caspar

    2002-01-01

    Autorist lk 133. Sisu: "ta surnud sõbrad..." ; "ta kummaline hüüd..." ; "nii salakaval oli üks naine..." ; "ta tõmbas..." ; "mul meeles üks..." ; "rohi saab lahti iga päev üha..." ; "aeg riietab end lahti..." ; "ta kunagi..." ; "me riietume..." ; "ma tean armastuse põsepuna..." ; "kunas see suudlus..." ; "sina mu mälestuste tydruk..." ; "su õde mind armastas..." ; "hingata valutult..." ; "need juuksed pesemata..." ; "ah saab olema..." ; "siit natuke maad edasi..."

  3. The Geography of the ta-ra-si-ja

    DEFF Research Database (Denmark)

    Nosch, Marie-Louise Bech

    2000-01-01

    Thies paper demonstrates how ta-ra-si-ja is connected to a fixed series of toponyms in Crete, and concludes that ta-ra-si-ja is a duty limited to certain places......Thies paper demonstrates how ta-ra-si-ja is connected to a fixed series of toponyms in Crete, and concludes that ta-ra-si-ja is a duty limited to certain places...

  4. "ta surnud sõbrad..." : [luuletused] / Caspar Tops

    Index Scriptorium Estoniae

    Tops, Caspar

    2002-01-01

    Autorist lk 133. Sisu: "ta surnud sõbrad..." ; "ta kummaline hüüd..." ; "nii salakaval oli üks naine..." ; "ta tõmbas..." ; "mul meeles üks..." ; "rohi saab lahti iga päev üha..." ; "aeg riietab end lahti..." ; "ta kunagi..." ; "me riietume..." ; "ma tean armastuse põsepuna..." ; "kunas see suudlus..." ; "sina mu mälestuste tydruk..." ; "su õde mind armastas..." ; "hingata valutult..." ; "need juuksed pesemata..." ; "ah saab olema..." ; "siit natuke maad edasi..."

  5. Improving High-resolution Spatial Estimates of Precipitation in the Equatorial Americas

    Science.gov (United States)

    Verdin, A.; Rajagopalan, B.; Funk, C. C.

    2013-12-01

    Drought and flood management practices require accurate estimates of precipitation in space and time. However, data is sparse in regions with complicated terrain (such as the Equatorial Americas), often in valleys (where people farm), and of poor quality. Consequently, extreme precipitation events are poorly represented. Satellite-derived rainfall data is an attractive alternative in such regions and is being widely used, though it too suffers from problems such as underestimation of extreme events (due to its dependency on retrieval algorithms) and the indirect relationship between satellite radiation observations and precipitation intensities. Thus, it seems appropriate to blend satellite-derived rainfall data of extensive spatial coverage with rain gauge data in order to provide a more robust estimate of precipitation. To this end, in this research we offer three techniques to blend rain gauge data and the Climate Hazards group InfraRed Precipitation (CHIRP) satellite-derived precipitation estimate for Central America and Colombia. In the first two methods, the gauge data is assigned to the closest CHIRP grid point, where the error is defined as r = Yobs - Ysat. The spatial structure of r is then modeled using physiographic information (Easting, Northing, and Elevation) by two methods (i) a traditional Cokriging approach whose variogram is calculated in Euclidean space and (ii) a nonparametric method based on local polynomial functional estimation. The models are used to estimate r at all grid points, which is then added to the CHIRP, thus creating an improved satellite estimate. We demonstrate these methods by applying them to pentadal and monthly total precipitation fields during 2009. The models' predictive abilities and their ability to capture extremes are investigated. These blending methods significantly improve upon the satellite-derived estimates and are also competitive in their ability to capture extreme precipitation. The above methods assume

  6. Atomically engineering Cu/Ta interfaces.

    Energy Technology Data Exchange (ETDEWEB)

    Webb, Edmund Blackburn, III (, Sandia National Laboratories, Albuquerque, NM); Zhou, Xiao Wang

    2007-09-01

    This report summarizes the major research and development accomplishments for the late start LDRD project (investment area: Enable Predictive Simulation) entitled 'Atomically Engineering Cu/Ta Interfaces'. Two ultimate goals of the project are: (a) use atomistic simulation to explore important atomistic assembly mechanisms during growth of Cu/Ta multilayers; and (b) develop a non-continuum model that has sufficient fidelity and computational efficiency for use as a design tool. Chapters 2 and 3 are essentially two papers that address respectively these two goals. In chapter 2, molecular dynamics simulations were used to study the growth of Cu films on (010) bcc Ta and Cu{sub x}Ta{sub 1-x} alloy films on (111) fcc Cu. The results indicated that fcc crystalline Cu films with a (111) texture are always formed when Cu is grown on Ta. The Cu films are always polycrystalline even when the Ta substrate is single crystalline. These polycrystalline films are composed of grains with only two different orientations, which are separated by either orientational grain boundaries or misfit dislocations. Periodic misfit dislocations and stacking fault bands are observed. The Cu film surface roughness was found to decrease with increasing adatom energy. Due to a Cu surface segregation effect, the Cu{sub x}Ta{sub 1-x} films deposited on Cu always have a higher Cu composition than that used in the vapor mixture. When Cu and Ta compositions in the films are comparable, amorphous structures may form. The fundamental origins for all these phenomena have been studied in terms of crystallography and interatomic interactions. In chapter 3, a simplified computational method, diffusional Monte Carlo (dMC) method, was developed to address long time kinetic processes of materials. Long time kinetic processes usually involve material transport by diffusion. The corresponding microstructural evolution of materials can be analyzed by kinetic Monte Carlo simulation methods, which

  7. Deformation Twinning During Nanoindentation of Nanocrystalline Ta

    OpenAIRE

    Wang, Y. M.; Hodge, A. M.; Biener, J.; Hamza, A.V.; Barnes, D E; Liu, Kai; Nieh, T. G.

    2005-01-01

    The deformation mechanism of body-centered cubic (bcc) nanocrystalline tantalum with grain sizes of 10–30 nm is investigated by nanoindentation, scanning electron microscopy and high-resolution transmission electron microscopy. In a deviation from molecular dynamics simulations and existing experimental observations on other bcc nanocrystalline metals, the plastic deformation of nanocrystalline Ta during nanoindentation is controlled by deformation twinning. The observation of multiple twin i...

  8. Comparison of sensible heat flux estimates using AVHRR with scintillometer measurements over semi-arid grassland in northwest Mexico

    NARCIS (Netherlands)

    Watts, C.J.; Chehbouni, A.; Rodriguez, J.C.; Kerr, Y.H.; Hartogensis, O.K.; Bruin, de H.A.R.

    2000-01-01

    The problems associated with the validation of satellite-derived estimates of the surface fluxes are discussed and the possibility of using the large aperture scintillometer is investigated. Simple models are described to derive surface temperature and sensible heat flux from the advanced very high

  9. Nanoindentation and Adhesion Properties of Ta Thin Films

    Directory of Open Access Journals (Sweden)

    Yuan-Tsung Chen

    2013-01-01

    Full Text Available Ta films were sputtered onto a glass substrate with thicknesses from 500 Å to 1500 Å under the following conditions: (a as-deposited films were maintained at room temperature (RT, (b films were postannealed at TA=150°C for 1 h, and (c films were postannealed at TA=250°C for 1 h. X-ray diffraction (XRD results revealed that the Ta films had a body-centered cubic (BCC structure. Postannealing conditions and thicker Ta films exhibited a stronger Ta (110 crystallization than as-deposited and thinner films. The nanoindention results revealed that Ta thin films are sensitive to mean grain size, including a valuable hardness (H and Young’s modulus (E. High nanomechanical properties of as-deposited and thinner films can be investigated by grain refinement, which is consistent with the Hall-Petch effect. The surface energy of as-deposited Ta films was higher than that in postannealing treatments. The adhesion of as-deposited Ta films was stronger than postannealing treatments because of crystalline degree effect. The maximal H and E and the optimal adhesion of an as-deposited 500-Å-thick Ta film were 15.6 GPa, 180 GPa, and 51.56 mJ/mm2, respectively, suggesting that a 500-Å-thick Ta thin film can be used in seed and protective layer applications.

  10. Age estimation in the living

    DEFF Research Database (Denmark)

    Larsen, Sara Tangmose; Thevissen, Patrick; Lynnerup, Niels;

    2015-01-01

    in the living on a full set of third molar scores. A cross sectional sample of 854 panoramic radiographs, homogenously distributed by sex and age (15.0-24.0 years), were randomly split in two; a reference sample for obtaining age estimates including a 95% prediction interval according to TA; and a validation...... (validation sample) fell within the 95% prediction interval. Moreover, at a sensitivity and specificity of 0.824 and 0.937 in males and 0.814 and 0.827 in females, TA performs well in differentiating between being a minor as opposed to an adult. Although accuracy does not outperform other methods, TA provides...

  11. Direct Electrolytic Reduction of Solid Ta2O5 to Ta with SOM Process

    Science.gov (United States)

    Chen, Chaoyi; Yang, Xiaqiong; Li, Junqi; Lu, Xionggang; Yang, Shufeng

    2016-06-01

    A process that uses the solid-oxide-oxygen-ion conducting membrane has been investigated to produce tantalum directly from solid Ta2O5 in molten CaCl2 or a molten mixture of 55.5MgF2-44.5CaF2 (in wt pct). The sintered porous Ta2O5 pellet was employed as the cathode, while the liquid copper alloy, saturated with graphite powder and encased in a one-end-closed yttria-stabilized-zirconia (YSZ) tube, acted as the anode. The electrolysis potential in this method is higher than that of the Fray-Farthing-Chen Cambridge process because the YSZ membrane tube blocks the melts to electrolyze, and only Ta2O5 is will be electrolyzed. The microstructures of reduced pellets and a cyclic voltammogram of solid Ta2O5 in molten CaCl2 were analyzed. In addition, the influence of particle size and porosity of the cathode pellets on metal-oxide-electrolyte, three-phase interlines was also discussed. The results demonstrate that the sintering temperature of cathode pellets and electrolytic temperature play important roles in the electrochemical process. Furthermore, this process can be used to produce Ta metal efficiently without the expensive cost of pre-electrolysis and generation of harmful by-products.

  12. MoNbTaV Medium-Entropy Alloy

    Directory of Open Access Journals (Sweden)

    Hongwei Yao

    2016-05-01

    Full Text Available Guided by CALPHAD (Calculation of Phase Diagrams modeling, the refractory medium-entropy alloy MoNbTaV was synthesized by vacuum arc melting under a high-purity argon atmosphere. A body-centered cubic solid solution phase was experimentally confirmed in the as-cast ingot using X-ray diffraction and scanning electron microscopy. The measured lattice parameter of the alloy (3.208 Å obeys the rule of mixtures (ROM, but the Vickers microhardness (4.95 GPa and the yield strength (1.5 GPa are about 4.5 and 4.6 times those estimated from the ROM, respectively. Using a simple model on solid solution strengthening predicts a yield strength of approximately 1.5 GPa. Thermodynamic analysis shows that the total entropy of the alloy is more than three times the configurational entropy at room temperature, and the entropy of mixing exhibits a small negative departure from ideal mixing.

  13. 75 FR 43556 - TA-W-73,381, MT Rail Link, Inc., Missoula, MT; TA-W-73,381A, Billings, MT; TA-W-73,381B, Laurel...

    Science.gov (United States)

    2010-07-26

    ... Employment and Training Administration TA-W-73,381, MT Rail Link, Inc., Missoula, MT; TA-W-73,381A, Billings, MT; TA-W-73,381B, Laurel, MT; TA-W-73,381C, Livingston, MT; TA-W-73,381D, Helena, MT; Amended... applicable to TA-W-73,381 is hereby issued as follows: All workers of Montana Rail Link, Inc.,...

  14. Paleoclimate from Tree Rings of Picea morrisonicola in Ta-Ta-Chia Area of Central Taiwan

    Science.gov (United States)

    Chen, T.; Wright, W. E.; Wei, K.; Cook, E. R.

    2009-12-01

    Almost no dendrochronology has been reported internationally from Taiwan, despite the existence of many dendrochronologically appropriate tree species. In this study, we reconstruct the regional paleoclimate using a multi-century tree ring-width chronology developed from Picea morrisonicola ( the endemic Taiwan Spruce), a subtropical species growing in the Ta-Ta-Chia subalpine mountain areas of central Taiwan. Picea morrisonicola in Taiwan is the only member of the Picea genus whose distribution crosses the Tropic of Cancer. Statistical analysis of the climate signal demonstrates that both the temperature and precipitation have significant effects on tree growth.

  15. Adjustments of the TaD electron density reconstruction model with GNSS-TEC parameters for operational application purposes

    Directory of Open Access Journals (Sweden)

    Belehaki Anna

    2012-12-01

    Full Text Available Validation results on the latest version of TaD model (TaDv2 show realistic reconstruction of the electron density profiles (EDPs with an average error of 3 TECU, similar to the error obtained from GNSS-TEC calculated paremeters. The work presented here has the aim to further improve the accuracy of the TaD topside reconstruction, adjusting the TEC parameter calculated from TaD model with the TEC parameter calculated by GNSS transmitting RINEX files provided by receivers co-located with the Digisondes. The performance of the new version is tested during a storm period demonstrating further improvements in respect to the previous version. Statistical comparison of modeled and observed TEC confirms the validity of the proposed adjustment. A significant benefit of the proposed upgrade is that it facilitates the real-time implementation of TaD. The model needs a reliable measure of the scale height at the peak height, which is supposed to be provided by Digisondes. Oftenly, the automatic scaling software fails to correctly calculate the scale height at the peak, Hm, due to interferences in the receiving signal. Consequently the model estimated topside scale height is wrongly calculated leading to unrealistic results for the modeled EDP. The proposed TEC adjustment forces the model to correctly reproduce the topside scale height, despite the inaccurate values of Hm. This adjustment is very important for the application of TaD in an operational environment.

  16. Er{sup 3+} diffusion in LiTaO{sub 3} crystal

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, De-Long, E-mail: dlzhang@tju.edu.cn [Department of Opto-electronics and Information Engineering, School of Precision Instruments and Opto-electronics Engineering, Tianjin University, Tianjin 300072 (China); Key Laboratory of Optoelectronic Information Technology (Ministry of Education), Tianjin University, Tianjin 300072 (China); Department of Electronic Engineering and State Key Laboratory of Millimeter Waves, City University of Hong Kong, 83 Tat Chee Avenue, Kowloon, Hong Kong (China); Zhang, Qun; Wong, Wing-Han [Department of Opto-electronics and Information Engineering, School of Precision Instruments and Opto-electronics Engineering, Tianjin University, Tianjin 300072 (China); Key Laboratory of Optoelectronic Information Technology (Ministry of Education), Tianjin University, Tianjin 300072 (China); Department of Electronic Engineering and State Key Laboratory of Millimeter Waves, City University of Hong Kong, 83 Tat Chee Avenue, Kowloon, Hong Kong (China); Pun, Edwin Yue-Bun [Department of Electronic Engineering and State Key Laboratory of Millimeter Waves, City University of Hong Kong, 83 Tat Chee Avenue, Kowloon, Hong Kong (China)

    2015-12-01

    Graphical abstract: Diffusion characteristics of Er{sup 3+} in LiTaO{sub 3} crystal were studied in a wide temperature range from 1000 to 1500 °C. The study shows that Er{sup 3+} doping has little effect on the LiTaO{sub 3} index. Li{sub 2}O out-diffusion is slight for a lower temperature while is moderate for a high temperature. The diffusion can be described by Fick's law of diffusion with a constant Er{sup 3+} diffusivity. Some characteristic diffusion parameters including diffusion constant, activation energy, solubility constant and heat of solution were obtained. In comparison with the case of LiNbO{sub 3}, Er{sup 3+} diffusion in LiTaO{sub 3} is at least two orders slower and Er{sup 3+} solubility in LiTaO{sub 3} is measurably lower. - Highlights: • Diffusion characteristics of Er{sup 3+} in LiTaO{sub 3} crystal were studied. • Diffusion constant is (1.05 ± 0.2) × 10{sup 10} μm{sup 2}/h and activation energy is 3.9 ± 0.04 eV. • Solubility constant is (9.12 ± 1.3) × 10{sup 24} cm{sup −3} and heat of solution is 1.33 ± 0.02 eV. • Er{sup 3+} diffusion in LiTaO{sub 3} is at least two orders slower than in LiNbO{sub 3}. • Er{sup 3+} solubility in LiTaO{sub 3} is measurably lower than in LiNbO{sub 3}. - Abstract: Some Er{sup 3+}-doped LiTaO{sub 3} plates were prepared by in-diffusion of Er-metal film locally coated onto congruent Z-cut substrate in air at a wide temperature range from 1000 to 1500 °C. After diffusion, Er{sup 3+}-doping effect on LiTaO{sub 3} refractive index and Li{sub 2}O out-diffusion arising from Er{sup 3+} in-diffusion were studied at first. Refractive indices at the doped and undoped surface parts were measured by prism coupling technique and the surface composition was estimated. The results show that Er{sup 3+} dopant has small contribution to the LiTaO{sub 3} index. Li{sub 2}O out-diffusion is slight (Li{sub 2}O content loss <0.3 mol%) for the temperature below 1300 °C while is moderate (Li{sub 2}O content loss

  17. A comparative study of the sensitivities of Salmonella typhimurium strains TA 98, TA 100 and TA 102 to hospital waste waters.

    Science.gov (United States)

    Gupta, Preeti; Mathur, P; Mathur, N; Aarya, B

    2014-07-01

    Hospitals are a release source of many chemical compounds in their wastewaters. In the present study Salmonella typhimurium strains TA 98, TA 100 and TA 102 were analyzed for their sensitivity to hospital waste waters. The results of the study showed that hospital waste waters consists of mutagens causing frame shift mutations and base pair substitutions and amongst the three strains used in this study, TA 102 was most effective which along with TA 98 can be used for quick assessment of genotoxicity of hospital waste waters prior to its discharge. Genotoxic potential of hospital waste waters from five major hospitals located in Jaipur and Delhi was studied. Such waste waters should be treated prior to their discharge. The results of this study call for further detailed study in this area of research.

  18. Limited Range Sesame EOS for Ta

    Energy Technology Data Exchange (ETDEWEB)

    Greeff, Carl William [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Crockett, Scott [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Rudin, Sven Peter [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Burakovsky, Leonid [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-03-30

    A new Sesame EOS table for Ta has been released for testing. It is a limited range table covering T ≤ 26, 000 K and ρ ≤ 37.53 g/cc. The EOS is based on earlier analysis using DFT phonon calculations to infer the cold pressure from the Hugoniot. The cold curve has been extended into compression using new DFT calculations. The present EOS covers expansion into the gas phase. It is a multi-phase EOS with distinct liquid and solid phases. A cold shear modulus table (431) is included. This is based on an analytic interpolation of DFT calculations.

  19. Identifying grain-size dependent errors on global forest area estimates and carbon studies

    Science.gov (United States)

    Daolan Zheng; Linda S. Heath; Mark J. Ducey

    2008-01-01

    Satellite-derived coarse-resolution data are typically used for conducting global analyses. But the forest areas estimated from coarse-resolution maps (e.g., 1 km) inevitably differ from a corresponding fine-resolution map (such as a 30-m map) that would be closer to ground truth. A better understanding of changes in grain size on area estimation will improve our...

  20. Social shaping of technology in TA and HTA

    DEFF Research Database (Denmark)

    Clausen, Christian; Yoshinaka, Yutaka

    2004-01-01

    The paper discusses how the social shaping of technology (SST) approach may be useful in understanding the role played by technology assessment within the context of technological development and change. It is proposed that an SST perspective on TA (or HTA) yields particular insight, regardless...... of whether or not the TA activity bases itself on a social shaping understanding of technology. This is because SST addresses the socially negotiated character of technological development, where TA itself may be construed as an element influencing the process of such negotiation. At the same time, TA...... is a construction, that is, itself a product of negotiations involving social actors. Thus, an understanding that TA is socially shaped, and is involved in the shaping of technology, opens up for a perspective on TA as both entailing constraints and enablements within the context of the particular agenda...

  1. Pressure dependence of X-rays produced by an LiTaO{sub 3} single crystal at low pressures

    Energy Technology Data Exchange (ETDEWEB)

    Hanamoto, Katsumi, E-mail: hana@md.okayama-u.ac.jp [Graduate School of Health Sciences, Okayama University, 5-1 Shikata-cho, 2-chome, Kita-ku, Okayama 700-8558 (Japan); Kawabe, Atsushi; Sakoda, Akihiro; Kataoka, Takahiro; Okada, Mari; Yamaoka, Kiyonori [Graduate School of Health Sciences, Okayama University, 5-1 Shikata-cho, 2-chome, Kita-ku, Okayama 700-8558 (Japan)

    2012-03-21

    The energy spectra of X-rays produced by an LiTaO{sub 3} single crystal have been measured at pressures of 5-50 Pa. The energy spectra showed that the amount of X-rays increased exponentially and the endpoint energy of the spectra increased linearly with the decrease of pressure at pressures of 10-25 Pa. A maximum endpoint energy of about 22 keV was obtained using an LiTaO{sub 3} single crystal with 0.5 mm thickness at the pressure of 10 Pa. The maximum energy produced by the present experimental setup was estimated assuming that the LiTaO{sub 3} single crystal forms a parallel-plate capacitor. The estimated energy reasonably agreed with the energy obtained. The pressure dependence of the endpoint energy was discussed in relation to the breakdown potential at low pressures.

  2. Thin TaC layer produced by ion mixing

    DEFF Research Database (Denmark)

    Barna, Árpád; Kotis, László; Pécz, Béla

    2012-01-01

    Ion-beam mixing in C/Ta layered systems was investigated. C 8nm/Ta 12nm and C 20nm/Ta 19nm/C 20nm layer systems were irradiated by Ga+ ions of energy in the range of 2–30keV. In case of the 8nm and 20nm thick C cover layers applying 5–8keV and 20–30keV Ga+ ion energy, respectively resulted...... in strongly asymmetric ion mixing; the carbon was readily transported to the Ta layer, while the reverse process was much weaker. Because of the asymmetrical transport the C/TaC interface remained sharp independently from the applied fluence. The carbon transported to the Ta layer formed Ta......Cx. The stoichiometry of the carbide produced varied along the depth. The TaCx layer contained implanted Ga, the concentration of which decreased with increasing depth. The thickness of the TaCx layer could be tailored by the ion fluence and energy making possible to produce coating layer of desired thickness....

  3. Generation of the regulatory protein rtTA transgenic mice

    Institute of Scientific and Technical Information of China (English)

    Kang Xu; Xin-Yan Deng; Ying Yue; Zhong-Min Guo; Bing Huang; Xun Hong; Dong Xiao; Xi-Gu Chen

    2005-01-01

    AIM: To translate Tet-on system into a conditional mouse model, in which hepatitis B or C virus (HBV or HCV) gene could be spatiotemporally expressed to overcome "immune tolerance" formed during the embryonic development and "immune escape" against hepatitis virus antigen(s), an effector mouse, carrying the reverse tetracycline-responsive transcriptional activator (rtTA) gene under the tight control of liver-specific human apoE promoter, is required to be generated. METHODS: To address this end, rtTA fragment amplified by PCR was effectively inserted into the vector of pLiv.7 containing apoE promoter to create the rtTA expressing vector, I.e., pApoE-rtTA. ApoE-rtTA transgenic fragment (-6.9 kb) released from pApoE-rtTA was transferred into mice by pronucleus injection, followed by obtaining one transgene (+) founder animal from microinjection through PCR and Southern blot analysis.RESULTS: rtTA transgene which could be transmitted to subsequent generation (F1) derived from founder was expressed in a liver-specific fashion. CONCLUSION: Taken together, these findings demonstrate that rtTA transgenic mice, in which rtTA expression is appropriately targeted to the murine liver, are successfully produced, which lays a solid foundation to 'off-on-off' regulate expression of target gene (s) (e.g., HBV and/or HCV) in transgenic mice mediated by Tet-on system.

  4. Electrons and phonons in the new 10 K superconductor CaTaN{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Smolinski, H.; Weber, W. [Dortmund Univ. (Germany). Theor. Phys. 2

    1997-11-01

    Electron and phonon calculations are presented for the ternary CaTaN{sub 2} of trigonal {alpha}-NaFeO{sub 2}-structure. Both density functional theory and the empirical tight-binding method are employed to yield a realistic description of electronic and vibrational properties, and also reasonable estimates of the electron-phonon coupling. Finally possible ways to enhance T{sub C} are discussed. (orig.) 12 refs.

  5. Measurement of fission anisotropy for 16O+181Ta

    Indian Academy of Sciences (India)

    Bivash R Behera; Subinit Roy; P Basu; M K Sharan; S Jena; M Satpathy; M L Chatterjee; S K Datta

    2001-07-01

    Anisotropies in fission fragment angular distributions measured for the system 16O+181Ta over a range of bombarding energies from 83 MeV to 120 MeV have been analysed. It is shown that statistical transition state model (TSM) with pre-scission neutron correction described adequately the measured anisotropy data. Strong friction parameter is found to be necessary to estimate the pre-saddle to pre-scission neutron ratio.

  6. Wet ammonia Synthesis of Semiconducting N:Ta2O5, Ta3N5 and β-TaON Films for Photoanode Applications

    OpenAIRE

    Dabirian, A.; Van't Spijker, H; Van de Krol, R.

    2012-01-01

    Tantalum oxynitride (β-TaON) is a promising photoanode material for photoelectrochemical water splitting. However, the synthesis of phase-pure β-TaON films is a challenging task. This paper describes a novel approach to achieve this by the controlled nitridation of Ta2O5 films under a flow of ammonia gas (ammonolysis), which was obtained by bubbling argon through an aqueous ammonium hydroxide solution followed by a 5 Å molecular sieve to remove the water. Depending on the nitridation conditio...

  7. Satellite-derived high resolution PM2.5 concentrations in Yangtze River Delta Region of China using improved linear mixed effects model

    Science.gov (United States)

    Ma, Zongwei; Liu, Yang; Zhao, Qiuyue; Liu, Miaomiao; Zhou, Yuanchun; Bi, Jun

    2016-05-01

    Satellite remotely sensed aerosol optical depth (AOD) provides an effective way to fill the spatial and temporal gaps left by ground PM2.5 monitoring network. Previous studies have established robust advanced statistical models to estimate PM2.5 using AOD data in China. However, their coarse resolutions (˜10 km or greater) of PM2.5 estimations are not enough to support the health effect studies at urban scales. In this study, 3 km AOD data from Moderate Resolution Imaging Spectroradiometer (MODIS) collection 6 products were used to estimate the high resolution PM2.5 concentrations in Yangtze Delta Region of China. We proposed a nested linear mixed effects (LME) model including nested month-, week-, and day-specific random effects of PM2.5-AOD relationships. Validation results show that the LME model only with day-specific random effects (non-nested model) used in previous studies has poor performance in the days without PM2.5-AOD matchups (the R2 of day-of-year-based cross validation (DOY-based CV) is 0.148). The results also show that our nested model cannot improve the performance of non-nested model in the days with PM2.5-AOD matchups (sample-based CV R2 = 0.671 for nested model vs. 0.661 for non-nested model), but can greatly improve the model performance beyond those days (DOY-based CV R2 = 0.339 for nested model vs. 0.148 for non-nested model). To further improve the model performance, we applied the "buffer models" (i.e., models fitted from datasets which ground PM2.5 were matched with the average AOD values within certain radius buffer zones of gridded PM2.5 data) on the 3 km AOD data since the "buffer models" has more days with PM2.5-AOD matchups and can provide more day-specific relationships. The results of this study show that 3 km MODIS C6 AOD data can be used to estimate PM2.5 concentrations and can provide more detailed spatial information for urban scale studies. The application of our nested LME model can greatly improve the accuracy of 3 km PM2

  8. Intrabeam Scattering Studies at CesrTA

    CERN Document Server

    Ehrlichman, M P; Heltsley, B; Peterson, D P; Rider, N; Rubin, D; Sagan, D; Shanks, J; Wang, S T; Campbell, R; Holtzapple, R

    2013-01-01

    Intrabeam scattering (IBS) limits the emittance and single-bunch current that can be achieved in electron or positron storage ring colliders, damping rings, and light sources. Much theoretical work on IBS exists, and while the theories have been validated in hadron and ion machines, the presence of strong damping makes IBS in lepton machines a different phenomenon. We present the results of measurements at CesrTA of IBS dominated beams, and compare the data with theory. The beams we study have parameters typical of those specified for the next generation of wiggler dominated storage rings: low emittance, small bunch length, and few GeV energy. Our measurements are in good agreement with IBS theory, provided a tail-cut procedure is applied.

  9. Characterization and Modeling of Nonfilamentary Ta/TaOx/TiO2/Ti Analog Synaptic Device.

    Science.gov (United States)

    Wang, Yu-Fen; Lin, Yen-Chuan; Wang, I-Ting; Lin, Tzu-Ping; Hou, Tuo-Hung

    2015-05-08

    A two-terminal analog synaptic device that precisely emulates biological synaptic features is expected to be a critical component for future hardware-based neuromorphic computing. Typical synaptic devices based on filamentary resistive switching face severe limitations on the implementation of concurrent inhibitory and excitatory synapses with low conductance and state fluctuation. For overcoming these limitations, we propose a Ta/TaOx/TiO2/Ti device with superior analog synaptic features. A physical simulation based on the homogeneous (nonfilamentary) barrier modulation induced by oxygen ion migration accurately reproduces various DC and AC evolutions of synaptic states, including the spike-timing-dependent plasticity and paired-pulse facilitation. Furthermore, a physics-based compact model for facilitating circuit-level design is proposed on the basis of the general definition of memristor devices. This comprehensive experimental and theoretical study of the promising electronic synapse can facilitate realizing large-scale neuromorphic systems.

  10. National Spatiotemporal Exposure Surface for NO2: Monthly Scaling of a Satellite-Derived Land-Use Regression, 2000-2010.

    Science.gov (United States)

    Bechle, Matthew J; Millet, Dylan B; Marshall, Julian D

    2015-10-20

    Land-use regression (LUR) is widely used for estimating within-urban variability in air pollution. While LUR has recently been extended to national and continental scales, these models are typically for long-term averages. Here we present NO2 surfaces for the continental United States with excellent spatial resolution (∼100 m) and monthly average concentrations for one decade. We investigate multiple potential data sources (e.g., satellite column and surface estimates, high- and standard-resolution satellite data, and a mechanistic model [WRF-Chem]), approaches to model building (e.g., one model for the whole country versus having separate models for urban and rural areas, monthly LURs versus temporal scaling of a spatial LUR), and spatial interpolation methods for temporal scaling factors (e.g., kriging versus inverse distance weighted). Our core approach uses NO2 measurements from U.S. EPA monitors (2000-2010) to build a spatial LUR and to calculate spatially varying temporal scaling factors. The model captures 82% of the spatial and 76% of the temporal variability (population-weighted average) of monthly mean NO2 concentrations from U.S. EPA monitors with low average bias (21%) and error (2.4 ppb). Model performance in absolute terms is similar near versus far from monitors, and in urban, suburban, and rural locations (mean absolute error 2-3 ppb); since low-density locations generally experience lower concentrations, model performance in relative terms is better near monitors than far from monitors (mean bias 3% versus 40%) and is better for urban and suburban locations (1-6%) than for rural locations (78%, reflecting the relatively clean conditions in many rural areas). During 2000-2010, population-weighted mean NO2 exposure decreased 42% (1.0 ppb [∼5.2%] per year), from 23.2 ppb (year 2000) to 13.5 ppb (year 2010). We apply our approach to all U.S. Census blocks in the contiguous United States to provide 132 months of publicly available, high

  11. High-resolution satellite-derived ocean surface winds in the Nordic-Barents seas region: Implications for ocean modeling (Invited)

    Science.gov (United States)

    Dukhovskoy, D. S.; Bourassa, M. A.; Hughes, P. J.

    2010-12-01

    High-resolution (0.25°) ocean surface wind velocity data derived from satellite observations are used to analyze winds in the Nordic-Barents seas during 2007-2008. For the analysis, a Cross-Calibrated, Multi-Platform (CCMP), multi-instrument ocean surface wind velocity data set is utilized. The product has been developed by National Aeronautics and Space Administration (NASA) within Making Earth Science data records for Use in Research Environments (MEaSUREs) Program. A variational method was used to combine wind measurements derived from satellite-born active and passive remote sensing instruments. In the objective procedure, winds from the European Centre for Medium-Range Weather Forecasts (ECMWF) Operational Analysis (DS111.1) were used as the background fields. The ocean surface wind fields are compared with those derived from the National Centers for Environmental Protection/National Center for Atmospheric Research (NCEP/NCAR) reanalysis. The NCEP/NCAR fields are commonly used to provide atmospheric forcing for Arctic Ocean models. The utility of using high-resolution winds in the ocean modeling is discussed. In particular, air-sea heat fluxes estimated from the two wind data sets are compared. It is anticipated that wind fields with higher spatial and temporal resolution will better resolve small-scale, short-lived atmospheric systems. As an example, the ice free region in the Nordic and Barents seas is frequently impacted by very intense cyclones known as “polar lows” with wind speeds near to or above gale force. A polar low forms over the sea and predominantly during the winter months. The size of these cyclones varies greatly from 100 to 1000 km. Presumably small-scale cyclones are misrepresented or not resolved in the NCAR fields leading to biases in the air-sea flux calculations in the ocean models. Inaccurate estimates of the air-sea fluxes eventually lead to biases in the Arctic Ocean model solutions.

  12. Microstructural and weldability evaluation of 310TaN

    Energy Technology Data Exchange (ETDEWEB)

    Lundin, C.D.; Qiao, C.Y.P. [Univ. of Tennessee, Knoxville, TN (United States); Swindeman, R.W. [Oak Ridge National Lab., TN (United States)

    1996-08-01

    Excellent weldability and good microstructural stability of 310TaN, in terms of the formation and growth of secondary phases at elevated temperature, was revealed in this investigation. The interganular stress corrosion resistance of 310TaN is superior to modified 800H and 310HCbN evaluated previously due to the fact that TaC, TaN and Ta(C,N) particles are more stable compared to Nb-rich or Ti-rich carbides, nitrides and carbonitrides presented in the other advanced alloys. Using resistance spot welding technique for which extremely fast cooling is a characteristic, it was found that a very minor amount of gain boundary liquation takes place during welding thermal cycling. The limited grain boundary liquation is of the eutectic type i.e., a low tendency to weld HAZ hot cracking.

  13. Cs10Ta29.27O78

    Directory of Open Access Journals (Sweden)

    Wolfgang Schnick

    2009-02-01

    Full Text Available Single crystals of caesium tantalate(V, Cs10Ta29.27O78, were obtained as a serendipitous product in a welded tantalum ampoule by a blank reaction of CsBr and bismuth subnitrate [Bi5O(OH9(NO34] with the container material. The crystal structure of the title compound is made up of a three-dimensional framework constituted by two types of layers, viz. (Ta6O15n and (Ta3O9n, parallel to (001, which are linked together by TaO6 octahedra (3m. symmetry along [001]. This framework has cavities where three independent Cs+ ions (3m. and overline{6}m2 symmetry, respectively are located. The compound reveals a Ta deficiency at one trigonal prismatic coordinated site (overline{6}m2 symmetry. The composition of the title compound was verified by energy-dispersive X-ray analysis of single crystals.

  14. Characterization of a TaJ Gene from Wheat

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A novel J-domain protein gene was cloned from wheat (Triticum aestivum L.) using RT-PCR technology and named as TaJ. The J-domain protein is defined by the presence of a J-domain. The cDNA of T. aestivum gene, TaJ (GenBank accession number: DQ789026), was 1 263 bp and contained a complete open reading frame (ORF) encoding a J-domain protein of 420 amino acid residues. The predicted amino acid sequence of TaJ possesses three functionally essential domains: the N-terminal J-domain which includes the highly conserved HPD tripeptide, an adjacent domain that is rich in glycine and phenylalanine residues (G/F) and a Cysteine-rich zinc-finger domain with four repeats of CxxCxGxG that is important for protein interactions. The C-terminal of TaJ was -CAQQ, a farnesylation motif. The full-length deduced amino acid sequence of TaJ is highly homologous to J-domain proteins from various plant species. Southern blot analysis indicated that a single copy of TaJ existed in wheat genome. The expression pattern of TaJ performed by real-time PCR demonstrated that heat shock (HS) at 37℃ induced the expression of TaJ rapidly and strongly, but the response of the TaJ gene to cold stress was much slower than that to HS. Tissue-specific expression analysis showed that the expression level of TaJ gene was much higher in leaves than that in roots.

  15. Atomic resolution imaging of precipitate transformation from cubic TaN to tetragonal CrTaN

    DEFF Research Database (Denmark)

    Danielsen, Hilmar Kjartansson; Hald, John; Somers, Marcel A. J.

    2012-01-01

    In 9–12% Cr creep-resistant steels Cr(V,Nb,Ta)N Z-phase is known to replace metastable (V,Nb,Ta)N MN precipitates at high temperatures. The precipitation process of Z-phase does not follow the classical nucleation theory, where dissolving MN particles provide constituents for Z-phase nucleation...

  16. A matrix clustering method to explore patterns of land-cover transitions in satellite-derived maps of the Brazilian Amazon

    Science.gov (United States)

    Müller-Hansen, Finn; Cardoso, Manoel F.; Dalla-Nora, Eloi L.; Donges, Jonathan F.; Heitzig, Jobst; Kurths, Jürgen; Thonicke, Kirsten

    2017-02-01

    Changes in land-use systems in tropical regions, including deforestation, are a key challenge for global sustainability because of their huge impacts on green-house gas emissions, local climate and biodiversity. However, the dynamics of land-use and land-cover change in regions of frontier expansion such as the Brazilian Amazon are not yet well understood because of the complex interplay of ecological and socioeconomic drivers. In this paper, we combine Markov chain analysis and complex network methods to identify regimes of land-cover dynamics from land-cover maps (TerraClass) derived from high-resolution (30 m) satellite imagery. We estimate regional transition probabilities between different land-cover types and use clustering analysis and community detection algorithms on similarity networks to explore patterns of dominant land-cover transitions. We find that land-cover transition probabilities in the Brazilian Amazon are heterogeneous in space, and adjacent subregions tend to be assigned to the same clusters. When focusing on transitions from single land-cover types, we uncover patterns that reflect major regional differences in land-cover dynamics. Our method is able to summarize regional patterns and thus complements studies performed at the local scale.

  17. Satellite-Derived Distributions, Inventories and Fluxes of Dissolved and Particulate Organic Matter Along the Northeastern U.S. Continental Margin

    Science.gov (United States)

    Mannino, A.; Hooker, S. B.; Hyde, K.; Novak, M. G.; Pan, X.; Friedrichs, M.; Cahill, B.; Wilkin, J.

    2011-01-01

    Estuaries and the coastal ocean experience a high degree of variability in the composition and concentration of particulate and dissolved organic matter (DOM) as a consequence of riverine and estuarine fluxes of terrigenous DOM, sediments, detritus and nutrients into coastal waters and associated phytoplankton blooms. Our approach integrates biogeochemical measurements, optical properties and remote sensing to examine the distributions and inventories of organic carbon in the U.S. Middle Atlantic Bight and Gulf of Maine. Algorithms developed to retrieve colored DOM (CDOM), Dissolved (DOC) and Particulate Organic Carbon (POC) from NASA's MODIS-Aqua and SeaWiFS satellite sensors are applied to quantify the distributions and inventories of DOC and POC. Horizontal fluxes of DOC and POC from the continental margin to the open ocean are estimated from SeaWiFS and MODIS-Aqua distributions of DOC and POC and horizontal divergence fluxes obtained from the Northeastern North Atlantic ROMS model. SeaWiFS and MODIS imagery reveal the importance of estuarine outflow to the export of CDOM and DOC to the coastal ocean and a net community production of DOC on the shelf.

  18. Thermodynamics of formation reactions of intermetallides Ni/sub 3/Ta and Ni/sub 2/Ta

    Energy Technology Data Exchange (ETDEWEB)

    Lyakishev, N.P.; Snitko, Yu.P.; Alekseev, V.I.; Levshin, G.A. (Tsentral' nyj Nauchno-Issledovatel' skij Inst. Chernoj Metallurgii, Moscow (USSR))

    1981-01-01

    Thermodynamical functions of the formation of Ni/sub 3/Ta and Ni/sub 2/Ta intermetallides are studied when investigating the electromotive force of the cell MoVertical BarTa/sub 2/O/sub 5/, Nisub(x)Tasub(y)Vertical Bar0.99ThOsub(2)i0.01 CaOVertical Bar Fe, Fesub(0.95)OVertical BarMo in the temperature range of 1173-1323 K. Thermodynamical functions of Ni/sub 3/Ta and Ni/sub 2/Ta formation are equal to: ..delta..Gsub(f)sup(0) (1273 K) 31.70 and 28.86; ..delta..Hsub(f)sup(0) (1173-1323 K) 27.88, 07.9 kcal/mol; ..delta..Ssub(f)sup(0) (1173-1323 K) 3,U and 0.75 cal/molxdegree, respectively.

  19. Optical properties analysis of Ta-doped TiO{sub 2} thin films on LaAlO{sub 3} substrates

    Energy Technology Data Exchange (ETDEWEB)

    Nurfani, Eka; Sutjahja, Inge M. [Department of Physics, Institut Teknologi Bandung, Ganesa 10 Bandung 40132 (Indonesia); Rusydi, Andrivo; Darma, Yudi, E-mail: yudi@fi.itb.ac.id [Department of Physics, Institut Teknologi Bandung, Ganesa 10 Bandung 40132 (Indonesia); Singapore Synchrotron Light Source, National University of Singapore, 5 Research Link, Singapore 117603 (Singapore); NUSNNI-Nanocore, Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542 (Singapore)

    2015-09-30

    We study optical properties of Ta-doped TiO{sub 2} thin film on LaAlO{sub 3} substrate using spectroscopy ellipsometry (SE) analysis at energy range of 0.5 – 6.5 eV. Room temperature SE data for Ψ (amplitude ratio) and Δ (phase difference) between p- and s- polarized light waves are taken with multiple incident angles at several spots on the samples. Here, absorption coefficient has been extracted from SE measurements at photon incident angle of 70° for different Ta concentration (0.01, 0.4, and 5 at. %). Multilayer modelling is performed which takes into account reflections at each interface through Fresnel coefficients to obtain reasonably well the fitting of Ψ and Δ data simultaneously. As the results, we estimate that film thickness increases by increasing Ta concentration accompanied by the formation of a new electronic structure. By increasing Ta impurities, the blueshift of absorption coefficient (α) peaks is observable. This result indicates that TiO{sub 2} thin film becomes optically resistive by introducing Ta doping. Schematic model of interband transition inTiO{sub 2}:Ta will be proposed base on obtained optical properties. This study enables us to predict the role of Ta doping on the electronic and optical band structures of TiO{sub 2} thin film.

  20. Atmospheric COS measurements and satellite-derived vegetation fluorescence data to evaluate the terrestrial gross primary productivity of CMIP5 model

    Science.gov (United States)

    Peylin, Philippe; MacBean, Natasha; Launois, Thomas; Belviso, Sauveur; Cadule, Patricia; Maignan, Fabienne

    2016-04-01

    Predicting the fate of the ecosystem carbon stocks and their sensitivity to climate change strongly relies on our ability to accurately model the gross carbon fluxes, i.e. photosynthesis and respiration. The Gross Primary Productivity (GPP) simulated by the different terrestrial models used in CMIP5 show large differences however, not only in terms of mean value but also in terms of phase and amplitude, thus hampering accurate investigations into carbon-climate feedbacks. While the net C flux of an ecosystem (NEE) can be measured in situ with the eddy covariance technique, the GPP is not directly accessible at larger scales and usually estimates are based on indirect measurements combining different tracers. Recent measurements of a new atmospheric tracer, the Carbonyl sulphide (COS), as well as the global measurement of Solar Induced Fluorescence (SIF) from satellite instruments (GOSAT, GOME2) open a new window for evaluating the GPP of earth system models. The use of COS relies on the fact that it is absorbed by the leaves in a similar manner to CO2, while there seems to be nothing equivalent to respiration for COS. Following recent work by Launois et al. (ACP, 2015), there is a potential to evaluate model GPP from atmospheric COS and CO2 measurements, using a transport model and recent parameterizations for the non-photosynthetic sinks (oxic soils, atmospheric oxidation) and biogenic sources (oceans and anoxic soils) of COS. Vegetation uptake of COS is modeled as a linear function of GPP and the ratio of COS to CO2 rate of uptake by plants. For the fluorescence, recent measurements of SIF from space appear to be highly correlated with monthly variations of data-driven GPP estimates (Guanter et al., 2012), following a strong dependence of vegetation SIF on photosynthetic activity. These global measurements thus provide new indications on the timing of canopy carbon uptake. In this work, we propose a dual approach that combines the strength of both COS and SIF

  1. Modeling gross primary production of agro-forestry ecosystems by assimilation of satellite-derived information in a process-based model.

    Science.gov (United States)

    Migliavacca, Mirco; Meroni, Michele; Busetto, Lorenzo; Colombo, Roberto; Zenone, Terenzio; Matteucci, Giorgio; Manca, Giovanni; Seufert, Guenther

    2009-01-01

    In this paper we present results obtained in the framework of a regional-scale analysis of the carbon budget of poplar plantations in Northern Italy. We explored the ability of the process-based model BIOME-BGC to estimate the gross primary production (GPP) using an inverse modeling approach exploiting eddy covariance and satellite data. We firstly present a version of BIOME-BGC coupled with the radiative transfer models PROSPECT and SAILH (named PROSAILH-BGC) with the aims of i) improving the BIOME-BGC description of the radiative transfer regime within the canopy and ii) allowing the assimilation of remotely-sensed vegetation index time series, such as MODIS NDVI, into the model. Secondly, we present a two-step model inversion for optimization of model parameters. In the first step, some key ecophysiological parameters were optimized against data collected by an eddy covariance flux tower. In the second step, important information about phenological dates and about standing biomass were optimized against MODIS NDVI. Results obtained showed that the PROSAILH-BGC allowed simulation of MODIS NDVI with good accuracy and that we described better the canopy radiation regime. The inverse modeling approach was demonstrated to be useful for the optimization of ecophysiological model parameters, phenological dates and parameters related to the standing biomass, allowing good accuracy of daily and annual GPP predictions. In summary, this study showed that assimilation of eddy covariance and remote sensing data in a process model may provide important information for modeling gross primary production at regional scale.

  2. First-principles study of the charge transfer and evolution of Si doping 2N2Ta islands adsorption on TaN (001) surfaces

    Science.gov (United States)

    Ren, Yuan; Zhang, Honglv; Zhang, Chao; Zeng, Haiqing; Liu, Xuejie

    2017-01-01

    The separation and aggregation of Si atoms around TaN grains during deposition of Ta-Si-N nanocomposite films were studied, and the adsorption energies, charge transfer and atomic partial density of state of Si-2N2Ta islands on the TaN (001) surface and diffusion energy of the islands during their evolution were evaluated using the first-principles method based on density functional theory (DFT). In the lowest total energy stable configuration, N and Ta atoms tended to combine to form 2N2Ta islands, whereas Si atoms tended to stay at a position diagonal to the Ta atom outside of the island. Si atoms entered the position of the missing N atom of the TaN island and formed a substitute solid solution during Ta-Si-N growth. The Si atoms of the solid solution in the island could be easily extruded by Ta- or N-rich island during the deposition process. The process of Si atom extrusion by a N atom which was the configuration of N-by-2Ta1N1Si island evolved into Si-by-2N2Ta island in rich N-atom. The process of Si atom was extruded by the Ta atom which was the configuration of Ta-by-2N1Ta1Si island evolved into Si-of-2Ta2N island, that reduced the total energy of island. The diffusion energies of these evolutions were 0.974 and 1.712 eV, respectively. The Si atoms and TaN grain phase tended to separate during the deposition process. Si atoms could give way to Ta and N atoms during the Ta-Si-N nanocomposite film deposition process.

  3. Magnetism of Ta dichalcogenide monolayers tuned by strain and hydrogenation

    Energy Technology Data Exchange (ETDEWEB)

    Manchanda, Priyanka; Sellmyer, D. J.; Skomski, Ralph [Department of Physics and Astronomy and Nebraska Center for Materials and Nanoscience, University of Nebraska, Lincoln, Nebraska 68588 (United States); Sharma, Vinit [Department of Materials Science and Engineering and Institute of Materials Science, University of Connecticut, Storrs, Connecticut 06269 (United States); Yu, Hongbin [School of Electrical, Computer, and Energy Engineering, Arizona State University, Tempe, Arizona 85287 (United States)

    2015-07-20

    The effects of strain and hydrogenation on the electronic, magnetic, and optical properties of monolayers of Ta based dichalcogenides (TaX{sub 2}; X = S, Se, and Te) are investigated using density-functional theory. We predict a complex scenario of strain-dependent magnetic phase transitions involving paramagnetic, ferromagnetic, and modulated antiferromagnetic states. Covering one of the two chalcogenide surfaces with hydrogen switches the antiferromagnetic/nonmagnetic TaX{sub 2} monolayers to a semiconductor, and the optical behavior strongly depends on strain and hydrogenation. Our research opens pathways towards the manipulation of magnetic as well as optical properties for future spintronics and optoelectronics applications.

  4. Diffusion of $^{6}$Li in Ta and W

    CERN Document Server

    Vacik, J

    2006-01-01

    The objective of this work was the study of 6Li diffusion in the Ta and W refractory metals. The samples were prepared by ion implantation of 380 keV 6Li+ ions into W and Ta thin foils (up to the fluence of 1016 ions/cm2) and annealed up to the temperature 1940 °C. The depth profiles of 6Li were determined using the Thermal Neutron Depth Profiling (TNDP) technique. The results showed that diffusion of 6Li in both W and Ta foils is very complex and cannot be described by simple Fick’s laws. Trapping centers (in the subsurface layers of both W and Ta metals) were supposed in a trial to explain the 6Li diffusion behaviour. However, the 6Li depth profiles were only partly explained. Other aspects are necessary to take into account for more proper quantification; such as spatially dependent diffusion coefficients, etc.

  5. Charge transport properties of bulk Ta3N5 from first principles

    Science.gov (United States)

    Morbec, Juliana M.; Galli, Giulia

    2016-01-01

    Tantalum nitride is considered a promising material for photoelectrochemical water splitting, however, its charge transport properties remain poorly understood. We investigated polaronic and band transport in Ta3N5 using first-principles calculations. We first studied the formation of small polarons using density-functional theory (DFT) including DFT +U and hybrid functionals. We found that electron small polarons may occur but hole polarons are not energetically favorable. The estimated polaronic mobility for electrons is at least three orders of magnitude smaller than that measured in Ta3N5 films, suggesting that the main transport mechanism for both electrons and holes is bandlike. Since band transport is strongly affected by the carrier effective masses, and Ta3N5 is known to have large electron and hole effective masses, we also investigated whether substitutional impurities or strain may help lower the effective masses. We found a significant reduction in both electron and hole effective masses (up to 17% for electrons and 39% for holes) under applied strain, which may lead to a substantial improvement (up to 30% for electrons and 15% for holes) in the carrier mobilities.

  6. Ultrasensitive Anomalous Hall Effect in Ta/CoFe/Oxide/Ta Multilayers

    Directory of Open Access Journals (Sweden)

    Guang Yang

    2016-01-01

    Full Text Available Ultrahigh anomalous Hall sensitivity has been demonstrated in Ta/CoFe/Oxide/Ta multilayers. By changing oxides (MgO and HfO2 and annealing temperature, different annealing dependence of sensitivity was found in MgO-sample and HfO2-sample. For the MgO-sample, the anomalous Hall sensitivity reaches 18792 Ω/T in the as-deposited state and significantly reduces as annealing temperature increases. On the contrary, the sensitivity of the as-deposited HfO2-sample is only 765 Ω/T, while it remarkably increases with annealing temperature increasing, finally reaching 14741 Ω/T at 240°C. The opposite variation of anomalous sensitivity in two samples originates from the different change of magnetic anisotropy and anomalous Hall resistance during the annealing process. Our study provides a new perspective that both the choice of oxide material and the optimization of annealing treatment are important to the anomalous Hall sensitivity.

  7. Thermodynamic assessment of the Si-Ta system

    Energy Technology Data Exchange (ETDEWEB)

    Drouelle, I., E-mail: coletteservant@orange.fr [Laboratoire de Physicochimie de l' Etat Solide, ICMMO, Universite de Paris-Sud, 91405 Orsay Cedex (France); Servant, C. [Laboratoire de Physicochimie de l' Etat Solide, ICMMO, Universite de Paris-Sud, 91405 Orsay Cedex (France)

    2013-02-25

    Highlights: Black-Right-Pointing-Pointer The thermodynamic modelling of the Si-Ta system is made with the CALPHAD method. Black-Right-Pointing-Pointer The liquid and bcc phases are treated with a solution model and compounds as stoichiometric. Black-Right-Pointing-Pointer The excess Gibbs energy of the solution phases is assessed with the T dependence by Kaptay. Black-Right-Pointing-Pointer The calculations based on the thermodynamic optimisation agree well with the experiments. - Abstract: The thermodynamic modeling of the silicon-tantalum binary system was carried out with the help of the CALPHAD (CALculation of PHAse Diagram) method. A solution model was used for the description of the liquid and bcc phases while the Si{sub 2}Ta, Si{sub 3}Ta{sub 5L}T, Si{sub 3}Ta{sub 5H}T SiTa{sub 2} and SiTa{sub 3} compounds are treated as stoichiometric. The excess Gibbs energy function of the solution phases was assessed with the recent exponential temperature dependence of the interaction parameters by Kaptay [1-3] and compared with the Redlich-Kister [4] polynomial equation results. The calculations based on the thermodynamic modeling are in good agreement with the phase diagram data and experimental thermodynamic values available in literature.

  8. Modelling the mechanical behaviour of heterogeneous Ta/TA6V welded joints: behaviour and failure criteria; Modelisation du comportement mecanique des liaisons soudees heterogenes Ta/TA6V: comportement et critere de rupture

    Energy Technology Data Exchange (ETDEWEB)

    Paris, Th

    2008-12-15

    As laser welding of two different materials (heterogeneous welding) leads to a joint having a characteristic size close to the millimetre, i.e. much smaller than that of a structure, and as such a junction displays completely different mechanical properties because of the metallurgical transformations induced by intense thermal loading, the aim of this research thesis is to develop a behaviour model, flexible and robust enough, to represent all together the mechanical behaviours of the Ta, the TA6V and the melted zone. This model must be able to take plasticity and visco-plasticity into account, and also to provide a failure criterion through damage mechanics and its coupling with the behaviour. The author first reports the experimental characterization of the base materials (Ta and TA6V) by using tensile tests under different strain rates and different directions, relaxation tests and fatigue shear tests. He also characterizes the melted zone by describing the influence of a thermal treatment (induced by welding) on the formation of the melted zone, and by using different tests: four point bending on notched specimens, nano-indentation test, and longitudinal tensile test. In a second part, the author develops the model within the framework of continuum thermodynamics, and explores the numerical issues. The last part deals with the validation of the model for the concerned materials (Ta and TA6V) and melted zone.

  9. Point defects stabilise cubic Mo-N and Ta-N

    Science.gov (United States)

    Koutná, Nikola; Holec, David; Svoboda, Ondřej; Klimashin, Fedor F.; Mayrhofer, Paul H.

    2016-09-01

    We employ ab initio calculations to investigate energetics of point defects in metastable rocksalt cubic Ta-N and Mo-N. Our results reveal a strong tendency to off-stoichiometry, i.e. defected structures are surprisingly predicted to be more stable than perfect ones with 1:1 metal-to-nitrogen stoichiometry. Despite the similarity of Ta-N and Mo-N systems in exhibiting this unusual behaviour, we also point out their crucial differences. While Ta-N significantly favours metal vacancies, Mo-N exhibits similar energies of formation regardless of the vacancy type (V Mo, V N) as long as their concentration is below ≈ 15~\\text{at}. % . The overall lowest energies of formation were obtained for \\text{T}{{\\text{a}}0.78}\\text{N} and \\text{M}{{\\text{o}}0.91}\\text{N} , which are hence predicted to be the most stable compositions. To account for various experimental conditions during synthesis, we further evaluated the phase stability as a function of chemical potential of individual species. The proposed phase diagrams reveal four stable compositions, \\text{M}{{\\text{o}}0.84}\\text{N} , \\text{M}{{\\text{o}}0.91}\\text{N} , \\text{Mo}{{\\text{N}}0.69} and \\text{Mo}{{\\text{N}}0.44} , in the case of Mo-N and nine stable compositions in the case of Ta-N indicating the important role of metal under-stoichiometry, since \\text{T}{{\\text{a}}0.75}\\text{N} and \\text{T}{{\\text{a}}0.78}\\text{N} significantly dominate the diagram. This is particularly important for understanding and designing experiments using non-equilibrium deposition techniques. Finally, we discuss the role of defect ordering and estimate a cubic lattice parameter as a function of defect contents and put them in the context of existing literature theoretical and experimental data.

  10. Effect of Ta concentration on the refractive index of TiO2:Ta studied by spectroscopic ellipsometry

    Science.gov (United States)

    Nurfani, Eka; Kurniawan, Robi; Muhammady, Shibghatullah; Marlina, Resti; Sutjahja, Inge M.; Winata, Toto; Rusydi, Andrivo; Darma, Yudi

    2016-04-01

    We have investigated optical properties of Ta-doped TiO2 thin film on LaAlO3 (LAO) substrate using Spectroscopic Ellipsometry (SE) at room temperature. Amplitude ratio Ψ and phase difference L1 between p- and s- polarized light waves are obtained by multiple incident angles measurement (60°, 70°, and 80°) at energy range of 0.5 - 6.5 eV. In order to obtain optical properties for every Ta concentrations (0.01, 0.4, and 5 at. %), multilayer modelling was performed simultaneously by using Drude-Lorentz model. Refractive index and optical dispersion parameters were determined by Wemple-DiDomenico relation. In general, refractive index at zero photon energy n(0) increases by increasing Ta concentration. Furthermore, optical band gap shows a significant increasing due to presence of Ta dopant. In addition, other optical constants are discussed as well.

  11. Pre-Test Analysis Predictions for the Shell Buckling Knockdown Factor Checkout Tests - TA01 and TA02

    Science.gov (United States)

    Thornburgh, Robert P.; Hilburger, Mark W.

    2011-01-01

    This report summarizes the pre-test analysis predictions for the SBKF-P2-CYL-TA01 and SBKF-P2-CYL-TA02 shell buckling tests conducted at the Marshall Space Flight Center (MSFC) in support of the Shell Buckling Knockdown Factor (SBKF) Project, NASA Engineering and Safety Center (NESC) Assessment. The test article (TA) is an 8-foot-diameter aluminum-lithium (Al-Li) orthogrid cylindrical shell with similar design features as that of the proposed Ares-I and Ares-V barrel structures. In support of the testing effort, detailed structural analyses were conducted and the results were used to monitor the behavior of the TA during the testing. A summary of predicted results for each of the five load sequences is presented herein.

  12. Combined experimental and theoretical assessments of the lattice dynamics and optoelectronics of TaON and Ta3N5

    KAUST Repository

    Nurlaela, Ela

    2015-06-15

    Presented herein is a detailed discussion of the properties of the lattice dynamic and optoelectronic properties of tantalum(V) oxynitride (TaON) and tantalum(V) nitride (Ta3N5), from experimental and theoretical standpoint. The active Raman and infra red (IR) frequencies of TaON and Ta3N5 were measured using confocal Raman and Fourier Transform Infrared spectroscopies (FTIR) and calculated using the linear response method within the density functional perturbation theory (DFPT). The detailed study leads to an exhaustive description of the spectra, including the symmetry of the vibrational modes. Electronic structures of these materials were computed using DFT within the range-separated hybrid HSE06 exchange–correlation formalism. Electronic and ionic contributions to the dielectric constant tensors of these materials were obtained from DFPT within the linear response method using the PBE functional. Furthermore, effective mass of photogenerated holes and electrons at the band edges of these compounds were computed from the electronic band structure obtained at the DFT/HSE06 level of theory. The results suggest that anisotropic nature in TaON and Ta3N5 is present in terms of dielectric constant and effective masses.

  13. Combined experimental and theoretical assessments of the lattice dynamics and optoelectronics of TaON and Ta3N5

    Science.gov (United States)

    Nurlaela, Ela; Harb, Moussab; del Gobbo, Silvano; Vashishta, Manish; Takanabe, Kazuhiro

    2015-09-01

    Presented herein is a detailed discussion of the properties of the lattice dynamic and optoelectronic properties of tantalum(V) oxynitride (TaON) and tantalum(V) nitride (Ta3N5), from experimental and theoretical standpoint. The active Raman and infra red (IR) frequencies of TaON and Ta3N5 were measured using confocal Raman and Fourier Transform Infrared spectroscopies (FTIR) and calculated using the linear response method within the density functional perturbation theory (DFPT). The detailed study leads to an exhaustive description of the spectra, including the symmetry of the vibrational modes. Electronic structures of these materials were computed using DFT within the range-separated hybrid HSE06 exchange-correlation formalism. Electronic and ionic contributions to the dielectric constant tensors of these materials were obtained from DFPT within the linear response method using the PBE functional. Furthermore, effective mass of photogenerated holes and electrons at the band edges of these compounds were computed from the electronic band structure obtained at the DFT/HSE06 level of theory. The results suggest that anisotropic nature in TaON and Ta3N5 is present in terms of dielectric constant and effective masses.

  14. Cervical Length & Leading Placental Edge to Internal OS Measurements - TA vs TV

    DEFF Research Database (Denmark)

    Westerway, Sue Campbell; Pedersen, Lars Henning; Hyett, Jon

    Brief Description of the Purpose of the Study: To compare cervical length/leading placental edge from the internal cervical os measurements obtained by both transabdominal (TA) and transvaginal (TV) approach and to assess intra / inter-observer variation for these measurements. Methods: Cross...... sectional study of 374 consecutive pregnancies with gestation 12 weeks to term. The cervical length was estimated as the distance from internal to external os, and the placenta / cervix distance as the leading placental edge to internal cervical os. Bland-Altman plots were used to evaluate the two methods...

  15. TA/TA list planning principles of TD-LTE system%TD-LTE系统TA及TA list规划原则

    Institute of Scientific and Technical Information of China (English)

    吕邦国; 于涛

    2013-01-01

      Firstly the TD-LTE system location area management mechanism is introduced in this paper. Secondly this paper analyzes the network paging mechanism, paging capacity according to the TD-LTE system capabilities and the current TD-LTE device performance. Lastly, by predicting the number of users as well as LTE cell single-user paging model, the TA/TA list planning principles and recommendations are given in this paper.%  本文首先介绍了TD-LTE系统位置区的管理机制,其次从TD-LTE系统能力以及目前TD-LTE设备性能等角度,分析了TD-LTE网络的寻呼机制和寻呼容量,最后通过预测LTE小区的用户数目以及单用户寻呼模型,给出了TA/TA list的规划原则和建议。

  16. Interface properties of Si-SiO{sub 2}-Ta{sub 2}O{sub 5} structure by cathodoluminescence spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Baraban, A. P.; Dmitriev, V. A.; Drozd, V. E.; Prokofiev, V. A.; Filatova, E. O. [St. Petersburg State University, St. Petersburg 198504 (Russian Federation); Samarin, S. N. [St. Petersburg State University, St. Petersburg 198504 (Russian Federation); School of Physics, The University of Western Australia, Perth, Western Australia 6009 (Australia)

    2016-02-07

    We studied formation of the SiO{sub 2}-T{sub 2}O{sub 5} interface in the Si-SiO{sub 2}-Ta{sub 2}O{sub 5} structure using Cathodoluminescence Spectroscopy (CLS). Analyzing the evolution of CLS spectrum of the Si-SiO{sub 2} structure while depositing the Ta{sub 2}O{sub 5} layer allowed to estimate an optical transmittance of the Ta{sub 2}O{sub 5} layer and its band gap. Spectral features related to the formation of the SiO{sub 2}-Ta{sub 2}O{sub 5} interface were identified by comparison of the experimental CL spectrum of the Si-SiO{sub 2}-Ta{sub 2}O{sub 5} structure and its simulated counterpart. This formation involves a decomposition of silanol groups at the outer surface of the SO{sub 2} layer and creation of the Si{sub x}Ta{sub y}O-type layer containing luminescence centers with the emission band centered at 3 eV photon energy.

  17. Enhanced post-annealing stability of perpendicular Ta/CoFeB/Mg/MgO multilayers by inhibiting Ta diffusion

    Energy Technology Data Exchange (ETDEWEB)

    Li, Xu-Jing; Jiang, Shao-Long; Zhang, Jing-Yan; Liu, Qian-Qian; Liu, Yi-Wei; Zhao, Jian-Cheng [Department of Materials Physics and Chemistry, University of Science and Technology Beijing, Beijing 100083 (China); Wu, Zheng-Long [Analytical and Testing Center, Beijing Normal University, Beijing 100875 (China); Feng, Chun, E-mail: fengchun@ustb.edu.cn [Department of Materials Physics and Chemistry, University of Science and Technology Beijing, Beijing 100083 (China); Li, Ming-Hua [Department of Materials Physics and Chemistry, University of Science and Technology Beijing, Beijing 100083 (China); Yu, Guang-Hua, E-mail: ghyu@mater.ustb.edu.cn [Department of Materials Physics and Chemistry, University of Science and Technology Beijing, Beijing 100083 (China)

    2016-03-01

    Graphical abstract: To reveal the underlying mechanism of Mg influence on the enhanced post-annealing stability of perpendicular Ta/CoFeB/Mg/MgO multilayers, the X-ray photoelectron spectroscopy analysis have been performed. It is found that a certain amount of Mg interlayer at the CoFeB/MgO interface could prevent the Ta oxidation to some extent due to the oxygen deficit MgO{sub x} (x < 1), and consequently lower the diffusion motivation of Ta from the bottom layer to the CoFeB/MgO interfaces to some extent during the annealing process. The prevention of Ta diffusion realizes the effective hybridization of Fe and O at the CoFeB/MgO interface and maintains interfacial magnetic anisotropy (K{sub CoFeB/MgO}). As a result, the perpendicular magnetic anisotropy at high annealing temperatures was maintained. - Highlights: • High annealing stability of perpendicular Ta/CoFeB/Mg/MgO multilayers was realized. • X-ray photoelectron spectroscopy analysis has been performed to explore the reasons. • The prevention of Ta diffusion was realized by introducing Mg at the CoFeB/MgO interface. - Abstracts: To reveal the underlying mechanism of Mg influence on the enhanced post-annealing stability of perpendicular Ta/CoFeB/Mg/MgO multilayers, the X-ray photoelectron spectroscopy analysis has been performed. It is found that a certain amount of Mg interlayer at the CoFeB/MgO interface could prevent the Ta oxidation, and consequently lower the diffusion motivation of Ta from the bottom layer to the CoFeB/MgO interfaces to some extent in the annealing process. The prevention of Ta diffusion realizes the effective hybridization of Fe and O at the CoFeB/MgO interface and maintains interfacial magnetic anisotropy (KCoFeB/MgO). As a result, the perpendicular magnetic anisotropy at high annealing temperatures is maintained.

  18. 77 FR 47671 - TA-W-81,520, T-Mobile USA, Inc., Call Center, Allentown, PA; TA-W-81,520G, T-Mobile USA, Inc...

    Science.gov (United States)

    2012-08-09

    ... Employment and Training Administration TA-W-81,520, T-Mobile USA, Inc., Call Center, Allentown, PA; TA- W-81..., Inc., Call Center, Allentown, Pennsylvania (TA-W-81,520), Fort Lauderdale, Florida (TA-W-81,520A), Frisco, Texas (TA-W-81,520B), Brownsville, Texas (TA-W- 81,520C), Lenexa, Kansas (TA-W-81,520D),...

  19. 75 FR 43564 - TA-W-71,483, Continental Airlines, Inc., Reservations Division, Houston, TX; TA-W-71,483A...

    Science.gov (United States)

    2010-07-26

    ... Employment and Training Administration TA-W-71,483, Continental Airlines, Inc., Reservations Division, Houston, TX; TA-W-71,483A, Continental Airlines, Inc., Reservations Division, Tampa, FL; TA-W-71,483B, Continental Airlines, Inc., Reservations Division, Salt Lake City, UT; Notice of Negative Determination...

  20. A new RHQT Nb3Al superconducting wire with a Ta/Cu/Ta three-layer filament-barrier structure

    Science.gov (United States)

    Takeuchi, Takao; Tsuchiya, Kiyosumi; Nakagawa, Kazuhiko; Nimori, Shigeki; Banno, Nobuya; Iijima, Yasuo; Kikuchi, Akihiro; Nakamoto, Tatsushi

    2012-06-01

    To suppress the low-magnetic-field instability (flux jumps in low magnetic fields) of a rapid-heating, quenching and transformation (RHQT) processed Nb3Al superconductor, we had previously modified the cross-sectional design of an RHQT Nb3Al by adopting a Ta filament-barrier structure. Unlike Nb barriers, Ta barriers are not superconducting in magnetic fields at 4.2 K so that they electromagnetically decouple filaments. However, small flux jumps still occurred at 1.8 K, which is a typical operating temperature for the magnets used in high-energy particle accelerators. Furthermore, poor bonding at the Ta/Ta interface between neighboring Ta-coated jelly-roll (JR) filaments frequently caused precursor wires to break during drawing. To overcome these problems, we fabricated a new RHQT Nb3Al wire with a Ta/Cu/Ta three-layer filament-barrier structure for which an internal stabilization technique (Cu rods encased in Ta are dispersed in the wire cross section) was extended. Removing the Ta/Ta interface in the interfilamentary barrier (JR filament/Ta/Cu/Ta/JR filament) allowed precursor wires to be drawn without breaking. Furthermore, the Cu filament barrier electromagnetically decoupled filaments to suppress flux jumps at 1.8 K. The ductile Cu layer also improved the bending strain tolerance of RHQT Nb3Al.

  1. Initiation of student-TA interactions in tutorials

    Directory of Open Access Journals (Sweden)

    Raymond A. Hodges

    2006-12-01

    Full Text Available At the University of Maryland we videotaped several semesters of tutorials as part of a large research project. A particular research task required us to locate examples of students calling the teaching assistants (TAs over for assistance with a physics question. To our surprise, examples of this kind of interaction were difficult to find. We undertook a systematic study of TA-student interactions in tutorial: In particular, how are the interactions initiated? Do the students call the TA over for help with a particular issue, does the TA stop by spontaneously, or does the worksheet require a discussion with the TA at that point? The initiation of the interaction is of particular interest because it provides evidence of the motivation for and purpose of the interaction. This paper presents the results of that systematic investigation. We discovered that the majority of student-TA interactions in tutorial are initiated by teaching assistants, confirmed our initial observation that relatively few interactions are initiated by students, and found, further, that even fewer interactions are worksheet initiated. Perhaps most importantly, we found that our sense of who initiates tutorial interactions—based on extensive but informal observations—is not necessarily accurate. We need systematic investigations to uncover the reality of our classroom experiences.

  2. Fibroblast functionality on novel Ti-30Ta nanotube array

    Energy Technology Data Exchange (ETDEWEB)

    Capellato, Patricia, E-mail: pat_capellato@yahoo.com.br [Department of Materials, Faculty of Engineering Guaratingueta, Sao Paulo State University-UNESP, Av. Ariberto Pereira da Cunha, 333, Pedregulho, CEP 12516-410, Guaratingueta, SP (Brazil); Smith, Barbara S. [School of Biomedical Engineering, Colorado State University, Fort Collins CO 80523 (United States); Popat, Ketul C. [School of Biomedical Engineering, Colorado State University, Fort Collins CO 80523 (United States); Department of Mechanical Engineering, Colorado State University, Fort Collins, CO 80523 (United States); Claro, Ana P.R. Alves [Department of Materials, Faculty of Engineering Guaratingueta, Sao Paulo State University-UNESP, Av. Ariberto Pereira da Cunha, 333, Pedregulho, CEP 12516-410, Guaratingueta, SP (Brazil)

    2012-10-01

    In this study, the mechanical substrate and topographical surface properties of anodized Ti-30Ta alloy were investigated using scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS) and contact angle measurement. The anodization process was performed in an electrolyte solution containing HF (48%) and H{sub 2}SO{sub 4} (98%) in the volumetric ratios 1:9 with the addition of 5% dimethyl sulfoxide (DMSO) at 15 V, 25 V and 35 V for 20 and 40 min, producing a nanotube architecture when anodized at 35 V for 40 min. Human dermal fibroblasts (HDF, neonatal) were utilized to evaluate the biocompatibility of Ti-30Ta nanotubes and Ti-30Ta alloy after 1 and 3 days of culture. Cellular adhesion, proliferation, viability, cytoskeletal organization and morphology were investigated using fluorescence microscope imaging, biochemical assay and SEM imaging respectively. The results presented identify altered material properties and improved cellular interaction on Ti-30Ta nanotubes as compared to Ti-30 Ta alloy. - Highlights: Black-Right-Pointing-Pointer The surface was modified by anodization, biomimetic treatment and ion bean etching. Black-Right-Pointing-Pointer SEM, EDS and contact angle measurements were used to characterize the surface. Black-Right-Pointing-Pointer Group 5 the most hydrophobic. Black-Right-Pointing-Pointer Group 4 the most hydrophilic. Black-Right-Pointing-Pointer Group 3 and 4 are the more indicated for biomedical application.

  3. The potential capacities of Ta'ziyeh in Modern Imagism

    Directory of Open Access Journals (Sweden)

    A.M Nedai

    2009-03-01

    Full Text Available Ta'ziyeh as the most important method in religious and ritual theatre in Iran has many capabilities which can be used in modern visualization. The only element in this theatre which has been studied is distancing in performance styles. But by studying the existent versions of Ta'ziyehs, there are other elements for recognition and use, which has not still been studied. The relationship between religious and ritual theatre with Ta'ziyeh and also their main themes helps to identify these elements and their capabilities. Meanwhile, the presence of music as an expressive and performing element provides a basis which can be used in finding a new manner of expression in visual/dramatic works (such as music videos. Studying on such elements as time-place interlace, character replacement, functions of music, and their effects on audiences, shows that Ta'ziyeh has specific capabilities in visualization (even in Cinema and Media. This article, through capitalizing on this subject and introducing one paradigm (Moses and poor Pilgrim, and comparing two versions of it, tries to represent these capabilities, and illuminates Ta'ziyeh's abilities for modern (and even postmodern visualization.

  4. Cloning and Functional Analysis of MADS-box Genes, TaAG-A and TaAG-B, from a Wheat K-type Cytoplasmic Male Sterile Line

    Directory of Open Access Journals (Sweden)

    Wenlong Yang

    2017-06-01

    Full Text Available Wheat (Triticum aestivum L. is a major crop worldwide. The utilization of heterosis is a promising approach to improve the yield and quality of wheat. Although there have been many studies on wheat cytoplasmic male sterility, its mechanism remains unclear. In this study, we identified two MADS-box genes from a wheat K-type cytoplasmic male sterile (CMS line using homology-based cloning. These genes were localized on wheat chromosomes 3A and 3B and named TaAG-A and TaAG-B, respectively. Analysis of TaAG-A and TaAG-B expression patterns in leaves, spikes, roots, and stems of Chinese Spring wheat determined using quantitative RT-PCR revealed different expression levels in different tissues. TaAG-A had relatively high expression levels in leaves and spikes, but low levels in roots, while TaAG-B had relatively high expression levels in spikes and lower expression in roots, stems, and leaves. Both genes showed downregulation during the mononucleate to trinucleate stages of pollen development in the maintainer line. In contrast, upregulation of TaAG-B was observed in the CMS line. The transcript levels of the two genes were clearly higher in the CMS line compared to the maintainer line at the trinucleate stage. Overexpression of TaAG-A and TaAG-B in Arabidopsis resulted in phenotypes with earlier reproductive development, premature mortality, and abnormal buds, stamens, and stigmas. Overexpression of TaAG-A and TaAG-B gives rise to mutants with many deformities. Silencing TaAG-A and TaAG-B in a fertile wheat line using the virus-induced gene silencing (VIGS method resulted in plants with green and yellow striped leaves, emaciated spikes, and decreased selfing seed set rates. These results demonstrate that TaAG-A and TaAG-B may play a role in male sterility in the wheat CMS line.

  5. Preparation and Characterization of TaN ALD Precursors

    Institute of Scientific and Technical Information of China (English)

    Delong Zhang; Tracy Yund; Cynthia A.Hoover

    2004-01-01

    High purity organic-tantalum precursors for thin film ALD TaN were synthesized and characterized.Vapor pressure and thermal stability of these precursors were studied.From the vapor pressure analysis,it was found that TBTEMT has a higher vapor pressure than any other published liquid TaN precursor,including TBTDET,TAITMATA,and IPTDET.Thermal stability of the alkyl groups on the precursors was investigated using a 1H NMR technique.The results indicated that the tertbutylimino group is the most stable group on TBTDET and TBTEMT as compared to the dialkylamido groups.Thermal stability of TaN precursors decreased in the following order:TBTDET > PDMAT > TBTEMT.In conclusion,precursor vapor pressure and thermal stability were tuned by making slight variations in the ligand sphere around the metal center.

  6. Synthesis and characterization of nanocrystalline NaTaO3

    Institute of Scientific and Technical Information of China (English)

    CHEN Jingfang; HU Long; ZHAO Jianling; TANG Chengchun; LI Yangxian

    2006-01-01

    Tantalum pentoxide reacts actively with concentrated NaOH solution under hydrothermal conditions at 180 ℃.In the reaction between NaOH solution and Ta2O5, the structure and composition of the tantalates depend on the reaction time, and the structure evolution results in a remarkable change in light absorption.Powder X-ray diffraction (XRD), scanning electron microscopy (SEM), and ultraviolet-visible (UV-Vis) diffused reflection spectrum were used to characterize various properties of the obtained solid products.At 180 ℃, the reaction proceeds rapidly.With the increase of time, the reflection peaks of unreacted Ta2O5 in the XRD patterns becomes weaker and weaker.Pure NaTaO3 is obtained after 60 min, which is well crystallized with a uniform cubic morphology.

  7. Microstructural evolution and creep of Fe-Al-Ta alloys

    Energy Technology Data Exchange (ETDEWEB)

    Prokopcakova, Petra; Svec, Martin [Technical University of Liberec (Czech Republic). Dept. of Material Science; Palm, Martin [Max-Planck-Institut fuer Eisenforschung GmbH, Duesseldorf (Germany). Structure and Nano-/Micromechanics of Materials

    2016-05-15

    The microstructural evolution in Fe-Al-Ta alloys containing 23 - 31 at.% Al and 1.5 - 2.2 at.% Ta has been studied in the temperature range 650 - 750 C by annealing for 1, 10, 100 and 1 000 h. The experiments confirm that in this temperature range the precipitation of the stable hexagonal C14 Laves phase is preceded by formation of coherent, metastable L2{sub 1} Heusler phase precipitates within the Fe-Al matrix. However, precipitates of C14 are observed after much shorter annealing times than previously assumed. Creep strength increases substantially with increasing Al content of the alloys because the solid solubility for Ta in the Fe-Al matrix increases with increasing Al content and solid-solution hardening contributes substantially to the observed high creep strength. It may therefore be that the microstructural changes during creep have no noticeable effect on creep strength.

  8. Nb/Ta variations of mafic volcanics on the Archean-Proterozoic boundary: Implications for the Nb/Ta imbalance

    Institute of Scientific and Technical Information of China (English)

    LIU Yongsheng; GAO Shan; WANG Xuance; HU Shenghong; WANG Jianqi

    2005-01-01

    The HFSE and REE of the Precambrian mafic volcanics from the North China craton demonstrate obvious A(Archean)-P(Proterozoic) boundary. The Neoarchean mafic vol-canics show weak correlation between HFSE and TiO2. Their superchondritic Nb/Ta ratio (18.8(1.2) could be attributed to partial melting of mantle peridotite in the presence of garnet. Compared with Neoarchean mafic volcanics, the Paleoproterozoic ones have higher HFSE contents and lower Nb/Ta ratio (15.6(2.9). The significantly elevated HFSE and REE contents of Paleoproterozoic mafic volcanics imply metasomatic enrichment of mantle source, in which Ti-rich silicates could be present as suggested by significant positive correlations between TiO2 and HFSE. The global database of Precambrian mafic volcanics shows a similar A-P boundary. 23 Archean mafic volcanic suites yield an average Nb/Ta ratio of 17.8(1.9 higher than or close to the PM value; Proterozoic mafic volcanics from 28 suites yield an average Nb/Ta ratio of 14.7(4.1 deficit could be mainly formed in post-Archean time. Archean mafic volcanics could be one of the geochemical reservoirs complementing the low Nb/Ta of the post-Archean continental crust and DM.

  9. A new synthesis route of perovskite-related Sr2TaO3N oxynitride via Sr2Ta6O10.188

    Science.gov (United States)

    Sarda, Narendra G.; Hayashi, Takanori; Takeuchi, Yuta; Harada, Kyosuke; Murai, Kei-Ichiro; Moriga, Toshihiro

    2016-12-01

    Formation process of the new layered perovskite Sr2TaO3N oxynitride having a K2NiF4-type structure from oxide precursor of Sr6Ta2O10.188 was examined under an ammonia flow. Using the oxide precursor, it is possible to make a Sr2TaO3N phase within a shorter period of the nitridation than the previous paper reported by Marchant et al. (J. Solid State Chem., 146: 390-393(1999)). Excess amount of strontium deviated from the stoichiometric composition of Sr/Ta=2 also seemed to promote the formation of Sr2TaO3N under the ammonia flow. The synthesized Sr2TaO3N after two cycles of 24h-nitridation of the oxide precursors showed brighter reddish-orange color than SrTaO2N.

  10. The Greenhouse Gas Climate Change Initiative (GHG-CCI): comparison and quality assessment of near-surface-sensitive satellite-derived CO2 and CH4 global data sets

    Science.gov (United States)

    Buchwitz, Michael

    2013-04-01

    The GHG-CCI project is one of several projects of the European Space Agency's (ESA) Climate Change Initiative (CCI). The goal of the CCI is to generate and deliver data sets of various satellite-derived Essential Climate Variables (ECVs) in line with GCOS (Global Climate Observing System) requirements. The "ECV Greenhouse Gases" (ECV GHG) is the global distribution of important climate relevant gases - atmospheric CO2 and CH4 - with a quality sufficient to obtain information on regional CO2 and CH4 sources and sinks. Two satellite instruments deliver the main input data for GHG-CCI: SCIAMACHY/ENVISAT and TANSO-FTS/GOSAT. The first order priority goal of GHG-CCI is the further development of retrieval algorithms for near-surface-sensitive column-averaged dry air mole fractions of CO2 and CH4, denoted XCO2 and XCH4, to meet the demanding user requirements. GHG-CCI focusses on four core data products: XCO2 from SCIAMACHY and TANSO and XCH4 from the same two sensors. For each of the four core data products at least two candidate retrieval algorithms have been independently further developed and the corresponding data products have been quality assessed and inter-compared. This activity is referred to as "Round Robin" (RR) activity within the CCI. The main goal of the RR was to identify for each of the four core products which algorithm to be used to generate the Climate Research Data Package (CRDP), which will essentially be the first version of the ECV GHG. This manuscript gives an overview about the GHG-CCI RR and related activities. This comprises the establishment of the user requirements, the improvement of the candidate retrieval algorithms and comparisons with ground-based observations and models. The manuscript summarizes the final RR algorithm selection decision and its justification. Comparison with ground-based Total Carbon Column Observing Network (TCCON) data indicates that the "breakthrough" single measurement precision requirement has been met for

  11. (Ag,Cu)-Ta-O ternaries as high-temperature solid-lubricant coatings.

    Science.gov (United States)

    Gao, Hongyu; Otero-de-la-Roza, Alberto; Gu, Jingjing; Stone, D'Arcy; Aouadi, Samir M; Johnson, Erin R; Martini, Ashlie

    2015-07-22

    Ternary oxides have gained increasing attention due to their potential use as solid lubricants at elevated temperatures. In this work, the tribological properties of three ternary oxides-AgTaO3, CuTaO3, and CuTa2O6-were studied using a combination of density-functional theory (DFT), molecular dynamics (MD) simulations with newly developed empirical potential parameters, and experimental measurements (AgTaO3 and CuTa2O6 only). Our results show that the MD-predicted friction force follows the trend AgTaO3 behavior of these materials.

  12. Preparation, characterization, and catalytic performance of Ta-HMS mesoporous molecular sieve

    Science.gov (United States)

    Li, Xuefeng; Zhang, Like; Gao, Huanxin; Chen, Qingling

    2016-08-01

    Various Ta-HMS (hexagonal mesoporous silica) samples with different Ta content were hydrothermally prepared and characterized by XRD, N2-adsorption, ICP-AES, FTIR, and UV-Vis spectroscopy. The catalytic performance of the samples was also evaluated in the epoxidation of cyclohexene with cumene hydroperoxide as oxidant. The regularity of mesoporous structure decreases while more extraframe Ta ions are formed with increasing the Ta content. Ta-HMS with Ta/Si ratio of 0.015 shows the highest conversion and selectivity in the studied epoxidation reaction. The catalyst can be used for three times without significant activity loss.

  13. Optical properties of 1T and 2H phases of TaS2 and TaSe2

    Indian Academy of Sciences (India)

    Sangeeta Sharma; S Auluck; M A Khan

    2000-03-01

    We have calculated the anisotropic frequency dependent dielectric function for the 1T and 2H phases of TaS2 and TaSe2 using the linear muffin tin orbital method within the atomic sphere approximation. We find significant anisotropy in the frequency dependent dielectric function for the 1T and 2H phases at low energies (less than 4 eV). Unfortunately there are no experimental data to compare with. The averaged dielectric function agrees with the available experimental data except that the calculated peak heights are underestimated and shifted to higher energies by 1–2 eV.

  14. Structure-dependent size effects in CuTa/Cu nanolaminates

    Energy Technology Data Exchange (ETDEWEB)

    Gu, C. [State-Key Laboratory for Mechanical Behavior of Material, Xi’an Jiaotong University Xi’an, 710049 (China); Wang, F., E-mail: wangfei@mail.xjtu.edu.cn [State Key Laboratory for Strength and Vibration of Mechanical Structures, Xian Jiaotong University Xi’an, 710049 (China); Huang, P., E-mail: huangping@mail.xjtu.edu.cn [State-Key Laboratory for Mechanical Behavior of Material, Xi’an Jiaotong University Xi’an, 710049 (China); Xu, K.W. [State-Key Laboratory for Mechanical Behavior of Material, Xi’an Jiaotong University Xi’an, 710049 (China); Lu, T.J. [State Key Laboratory for Strength and Vibration of Mechanical Structures, Xian Jiaotong University Xi’an, 710049 (China)

    2016-03-21

    CuTa monolayers with different Ta contents (34 at% and 37 at%) and CuTa/Cu multilayers with varying nanoscale Cu layer thickness (3–24 nm) were prepared by magnetron sputtering. Their microstructure and mechanical properties were investigated by means of high resolution transmission electron microscopy (HRTEM) and nanoindentation testing. The microstructure of CuTa34 was pure amorphous phase while that of CuTa37 was amorphous phase embedded with nanoparticles. Adding Cu layers into the two different CuTa monolayers led to CuTa-Cu interfaces with different microstructures. For CuTa34/Cu, the interface was relatively straight and the Cu layers exhibited textured growth. For CuTa37/Cu, the interface was wavy and GBs (grain boundaries) were formed in the Cu layers. To investigate the influence of the two different microstructures on multilayer deformation, the residue indentation morphologies of CuTa/Cu were observed under scanning electronic microscope (SEM). For both CuTa34/Cu and CuTa37/Cu, SBs (shear bands) could be effectively inhibited if the Cu layers had a proper thickness. Dominant deformation mechanisms and size effects were proposed and discussed for CuTa/Cu thin films possessing different interfaces and Cu layer structures.

  15. Ta Keo Temple Reconstruction Based on Terrestrial Laser Scanning Technology

    Science.gov (United States)

    Xi, X.; Wang, C.; Wan, Y. P.; Khuon, K. N.

    2015-08-01

    Ta Keo temple is one of the very famous temple complex of Angkor Wat in northwestern Cambodia. It has been suffering massive collapse and other serious damages in recent years. Nowadays, Terrestrial Laser Scanning(TLS) technology is considered as a wellestablished resource for heritage documentation and protection (Lerma et al, 2008; Reshetyuk, 2009). This paper used TLS to reconstruct Ta Keo Temple. Firstly, we acquired 71 scanning stations of points cloud data with high density and high accuracy, and over one thousand images with high spatial resolution about the temple. Secondly, the raw points cloud data were denoised, reduced and managed efficiently, and registrated using an adjusted ICP algorithm. Thirdly, a triangulation method was used to model most objects. At last, we mapped the texture data into the digital model and a 3-D model of Ta Keo with high accuracy was achieved. The authors focus on large object reconstruction by TLS technology, and pay much attention to the scanning design, multi-station data and the whole project's data registration, and texture mapping and so on. The research result will be useful for Ta Keo restoration, reconstruction and protection. Also, it is a good reference source for large complex buildings reconstruction when using terrestrial laser scanning technology.

  16. Studies on layer growth and interfaces on Ta-base thin layers by means of XPS; Untersuchungen zu Schichtwachstum und Grenzflaechen an Ta-basierten Duennschichten mittels XPS

    Energy Technology Data Exchange (ETDEWEB)

    Zier, M.

    2007-11-02

    In this thesis studies on the growth and on the formation of the interfaces of Ta and TaN layers on Si and SiO{sub 2} were performed. In the system TaN on SiO{sub 2} no reaction on the interface could be found. As the system with the mostly disturbed interface Ta on SiO{sub 2} was proved. Here a reduction of the SiO{sub 2} at simultaneous oxidation of the Ta was to be observed. Additionally tantalum silicide was formed to be considered concerning the bonding state as Ta{sub 5}Si{sub 3}, from which a double layer of a tantalum silicide and a tantalum suboxide resulted. A whole thickness of the double layer of above 1 nm resulted. In the system Ta on Si at the deposition of the film on the interface a tantalum silicide was formed to be characterized concerning the bonding state as TaSi{sub 2}. The thickness of the interlayer growed thereby up to 0.8 nm in form of islands. Finally in the system TaN on Si a silicon nitride formation during the deposition was observed, which was attributed to the insertion of adsorbed nitrogen from the sputtering atmosphere by recoil implantation of the sputtered Ta atoms. The silicon nitride interlayer growed thereby up to a thickness of 0.8 nm.

  17. The Wheat Mediator Subunit TaMED25 Interacts with the Transcription Factor TaEIL1 to Negatively Regulate Disease Resistance against Powdery Mildew.

    Science.gov (United States)

    Liu, Jie; Zhang, Tianren; Jia, Jizeng; Sun, Jiaqiang

    2016-03-01

    Powdery mildew, caused by the biotrophic fungal pathogen Blumeria graminis f. sp. tritici, is a major limitation for the production of bread wheat (Triticum aestivum). However, to date, the transcriptional regulation of bread wheat defense against powdery mildew remains largely unknown. Here, we report the function and molecular mechanism of the bread wheat Mediator subunit 25 (TaMED25) in regulating the bread wheat immune response signaling pathway. Three homoalleles of TaMED25 from bread wheat were identified and mapped to chromosomes 5A, 5B, and 5D, respectively. We show that knockdown of TaMED25 by barley stripe mosaic virus-induced gene silencing reduced bread wheat susceptibility to the powdery mildew fungus during the compatible plant-pathogen interaction. Moreover, our results indicate that MED25 may play a conserved role in regulating bread wheat and barley (Hordeum vulgare) susceptibility to powdery mildew. Similarly, bread wheat ETHYLENE INSENSITIVE3-LIKE1 (TaEIL1), an ortholog of Arabidopsis (Arabidopsis thaliana) ETHYLENE INSENSITIVE3, negatively regulates bread wheat resistance against powdery mildew. Using various approaches, we demonstrate that the conserved activator-interacting domain of TaMED25 interacts physically with the separate amino- and carboxyl-terminal regions of TaEIL1, contributing to the transcriptional activation activity of TaEIL1. Furthermore, we show that TaMED25 and TaEIL1 synergistically activate ETHYLENE RESPONSE FACTOR1 (TaERF1) transcription to modulate bread wheat basal disease resistance to B. graminis f. sp. tritici by repressing the expression of pathogenesis-related genes and deterring the accumulation of reactive oxygen species. Collectively, we identify the TaMED25-TaEIL1-TaERF1 signaling module as a negative regulator of bread wheat resistance to powdery mildew.

  18. Sea ice-atmospheric interaction: Application of multispectral satellite data in polar surface energy flux estimates

    Science.gov (United States)

    Steffen, Konrad; Key, J.; Maslanik, J.; Schweiger, A.

    1993-01-01

    This is the third annual report on: Sea Ice-Atmosphere Interaction - Application of Multispectral Satellite Data in Polar Surface Energy Flux Estimates. The main emphasis during the past year was on: radiative flux estimates from satellite data; intercomparison of satellite and ground-based cloud amounts; radiative cloud forcing; calibration of the Advanced Very High Resolution Radiometer (AVHRR) visible channels and comparison of two satellite derived albedo data sets; and on flux modeling for leads. Major topics covered are arctic clouds and radiation; snow and ice albedo, and leads and modeling.

  19. Tuning the charge density wave and superconductivity in CuxTaS2

    NARCIS (Netherlands)

    Wagner, K.E.; Morosan, E.; Hor, Y.S.; Tao, J.; Zhu, Y.; Sanders, T.; McQueen, T.M.; Zandbergen, H.W.; Williams, A.J.; West, D.V.; Cava, R.J.

    2008-01-01

    We report the characterization of layered 2H-type CuxTaS2 for 0≤x≤0.12. The charge density wave (CDW), at 70 K for TaS2, is destabilized with Cu doping. The sub-1 K superconducting transition in undoped 2H-TaS2 jumps quickly to 2.5 K at low x, increases to 4.5 K at the optimal composition Cu0.04TaS2

  20. Analysis of the Tuition Assistance Program: does the method of instruction matter in TA classes?

    OpenAIRE

    Mehay, Stephen L; Pema, Elda

    2010-01-01

    The Navy's Tuition Assistance (TA) program subsidizes the tuition costs of off-duty college classes for Navy personnel. Although prior studies have investigated the effect of completing college courses via TA on enlisted retention and promotion (Mehay and Pema, 2009), no prior study has examined the effect of the instructional methods in the courses taken via TA. Interest in course delivery methods has been stimulated by the rapid growth in online TA classes. This study analyzes the effects o...

  1. Influence of Ta content on hot corrosion behaviour of a directionally solidified nickel base superalloy

    Energy Technology Data Exchange (ETDEWEB)

    Han, F.F. [Superalloy Division, Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016 (China); Chang, J.X., E-mail: jxchang11s@imr.ac.cn [Superalloy Division, Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016 (China); Li, H.; Lou, L.H. [Superalloy Division, Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016 (China); Zhang, J. [Superalloy Division, Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016 (China); Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016 (China)

    2015-01-15

    Highlights: • Three nickel-base superalloys containing different Ta content were subjected to Na{sub 2}SO{sub 4}-induced hot corrosion. • Ta improved the hot corrosion resistance. • Ta decreased the diffusion rate of alloying elements. • Ta promoted the formation of (Cr, Ti)TaO{sub 4} layer. - Abstract: Hot corrosion behaviour of a directionally solidified nickel base superalloy with different tantalum (Ta) addition in fused sodium sulphate (Na{sub 2}SO{sub 4}) under an oxidizing atmosphere at 900 °C has been studied. It was shown that the hot corrosion resistance was improved by increasing of Ta content. The hot corrosion kinetics of the alloy with lower Ta content deviated from parabolic law after 60 h corrosion test, whereas the corrosion kinetics of the alloy with high Ta content followed the parabolic law before 60 h and with less mass change afterwards. A detailed microstructure study using scanning electron microscopy (SEM) equipped with an energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM) and X-ray diffraction (XRD) was performed to investigate the corrosion products and mechanisms. The beneficial effect of Ta was found to be resulted from a Ta-enriched (Cr, Ti)TaO{sub 4} layer inside the corrosion scale, which led to the retarding of the element diffusion so as to decrease the hot corrosion kinetics.

  2. Signature splitting and quasiparticle alignment in the yrast band of Ta-165

    NARCIS (Netherlands)

    Roux, DG; Fetea, MS; Gueorguieva, E; Babu, BRS; Newman, RT; Lawrie, JJ; Fearick, R; Aschman, DG; Beetge, R; Benatar, M; Mabala, GK; Mullins, SM; Murray, SHT; Naguleswaran, S; Rigollet, C; Sharpey-Schafer, JF; Smit, FD; Whittaker, WJ

    Excited states in Ta-165 were populated in the Nd-142(Al-27,4n)Ta-165 and Pr-141(Si-28,4n)Ta-165 reactions and investigated using the AFRODITE array. The yrast rotational decay sequence up to spin 53/2(-) is identified and assigned to the [514]9/2(-) configuration. The nuclear shape is investigated

  3. Preliminary results on the comparison between satellite derived ground temperature and in-situ measurement of soil CO2 flux and soil temperature at Solfatara of Pozzuoli (Naples, Italy)

    Science.gov (United States)

    Cardellini, Carlo; Silvestri, Malvina; Chiodini, Giovanni; Fabrizia Buongiorno, Maria

    2014-05-01

    temperature (at 10 cm depth) are measured periodically in about 400 point randomly distributed in the Solfatara crater area and in its surroundings. The data measured in 3 surveys performed from 2003 to 2010, in periods roughly correspondent to the available ASTER data, have been elaborated with the geostatistical method of Sequential Gaussian Simulation in order to obtain maps with a spatial resolution of 90X90 m to be compared to the ASTER data. The first results show a quite good correlations between ASTER derived temperatures and both temperatures and CO2 fluxes derived from ground measurement, especially in the most anomalous areas characterized by higher soil CO2 fluxes and temperatures. These first results encourage the possibility to use the satellite derived temperature as proxy of the CO2 fluxes and to implement methods to use long time series of satellite TIR data in a monitoring prospective.

  4. Ultrafast optical spectroscopy of quasi one dimensional Ta{sub 2}NiSe{sub 5}

    Energy Technology Data Exchange (ETDEWEB)

    Mor, Selene; Herzog, Marc; Monney, Claude; Staehler, Julia; Wolf, Martin [Fritz-Haber-Institut der MPG, Dept. of Phys. Chem., Berlin (Germany)

    2015-07-01

    Ta2NiSe5 is a layered compound in which atomic chains are aligned in the layers, forming a quasi one dimensional crystal structure. At 328 K, the system shows a structural change, which is accompanied by an electronic phase transition from a semiconductor to an excitonic insulator, with an estimated energy gap of about few hundreds millielectronvolts. Our aim is to unveil the microscopic mechanisms underlying the phase transition in Ta{sub 2}NiSe{sub 5}. The system is excited with a femtosecond Ti:sapphire fundamental laser pulse and the mid-infrared (MIR) transient optical response is monitored by ultrafast optical spectroscopy. We observe a fast rise of transient reflectivity, which decays exponentially. This incoherent response is superimposed by a coherent phonon oscillation. A preliminary study with white light (WL) probe beam shows that low repetition rate is mandatory to study the response of the photoexcited system. The analysis unveils the presence of two phonons at 3 and 4 THz, that dominate at high (HT) and low (LT) temperature, respectively. We study the time evolution of the two phonons in the LT phase. We reveal a finite lifetime for the LT phase phonon, whose amplitude decays within few picoseconds, while the HT phase phonon amplitude remains almost constant. The picture is supported by temperature-dependent Raman spectroscopy.

  5. Combined experimental and theoretical assessments of the lattice dynamics and optoelectronics of TaON and Ta{sub 3}N{sub 5}

    Energy Technology Data Exchange (ETDEWEB)

    Nurlaela, Ela; Harb, Moussab [Division of Physical Sciences and Engineering, KAUST Catalysis Center (KCC), King Abdullah University of Science and Technology (KAUST), 4700 KAUST, Thuwal 23955-6900 Saudi Arabia (Saudi Arabia); Gobbo, Silvano del [Solar and Photovoltaic Engineering Center, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900 (Saudi Arabia); Vashishta, Manish [Division of Physical Sciences and Engineering, KAUST Catalysis Center (KCC), King Abdullah University of Science and Technology (KAUST), 4700 KAUST, Thuwal 23955-6900 Saudi Arabia (Saudi Arabia); Takanabe, Kazuhiro, E-mail: kazuhiro.takanabe@kaust.edu.sa [Division of Physical Sciences and Engineering, KAUST Catalysis Center (KCC), King Abdullah University of Science and Technology (KAUST), 4700 KAUST, Thuwal 23955-6900 Saudi Arabia (Saudi Arabia)

    2015-09-15

    Presented herein is a detailed discussion of the properties of the lattice dynamic and optoelectronic properties of tantalum(V) oxynitride (TaON) and tantalum(V) nitride (Ta{sub 3}N{sub 5}), from experimental and theoretical standpoint. The active Raman and infra red (IR) frequencies of TaON and Ta{sub 3}N{sub 5} were measured using confocal Raman and Fourier Transform Infrared spectroscopies (FTIR) and calculated using the linear response method within the density functional perturbation theory (DFPT). The detailed study leads to an exhaustive description of the spectra, including the symmetry of the vibrational modes. Electronic structures of these materials were computed using DFT within the range-separated hybrid HSE06 exchange–correlation formalism. Electronic and ionic contributions to the dielectric constant tensors of these materials were obtained from DFPT within the linear response method using the PBE functional. Furthermore, effective mass of photogenerated holes and electrons at the band edges of these compounds were computed from the electronic band structure obtained at the DFT/HSE06 level of theory. The results suggest that anisotropic nature in TaON and Ta{sub 3}N{sub 5} is present in terms of dielectric constant and effective masses. - Graphical abstract: Detailed investigation has been conducted from combined experimental and theoretical approaches on Raman and IR spectroscopies, electronic structures, dielectric constants and effective masses of TaON and Ta{sub 3}N{sub 5}. - Highlights: • Crystal structures of TaON and Ta{sub 3}N{sub 5} are discussed based on XRD and DFT calculation. • Raman and IR spectra of TaON and Ta{sub 3}N{sub 5} materials are measured and computed by DFPT method. • Optoelectronic properties of TaON and Ta{sub 3}N{sub 5} are discussed. • Dielectric constant and effective masses of TaON and Ta{sub 3}N{sub 5} are calculated.

  6. Ultrafast magnetization and structural dynamics in the intercalated transition metal dichalcogenides Fe0.25TaS2 and Mn0.25TaS2.

    Science.gov (United States)

    Liu, Q; Zhu, X D; Wang, L H; Cheong, S-W; Tobey, R I

    2016-05-18

    We measure magnetization and structural dynamics in two intercalant-ordered transition metal dichalcogenides: Fe0.25TaS2 and Mn0.25TaS2. The structurally equivalent materials allow us to probe the effect of orbital angular momentum which is active in Fe0.25TaS2 and absent in Mn0.25TaS2. Interestingly, we find that the magnetooptics dynamics are nearly indistinguishable in these two materials, in contradiction to conventional explanations of a spin-lattice mechanism. We compare our results to other materials where spin-lattice demagnetization has been put forth as a demagnetization channel.

  7. Shock Hugoniot measurements on Ta to 0. 78 TPa

    Energy Technology Data Exchange (ETDEWEB)

    Froeschner, K.E.; Lee, R.S.; Chau, H.H.; Weingart, R.C.

    1983-08-18

    Symmetric impact shock Hugoniot measurements have been made on Ta with an electrically exploded foil gun system. The results obtained to date for the Hugoniot of Ta cover the range 0.19 to 0.78 TPa (impact velocities from 4.0 to 9.7 km/s) and agree with data obtained by other researchers to within 2.7% rms. Recent improvements in the system include electromagnetic shielding of impactor and target, continuous measurement of impactor velocity with a Fabry-Perot interferometer and computer-aided analysis of shot film. Conservative extrapolation from current operating conditions indicate that pressures of 1.1 to 1.5 TPa could be achieved with little difficulty.

  8. Ordering Effects in NbC and TaC

    Science.gov (United States)

    Venables, J. D.; Meyerhoff, M. H.

    1972-01-01

    By means of transmission electron microscopy and electron diffraction, evidence has been obtained for the existence of long range carbon atom ordering in single-crystal niobium carbide that has a carbon-to-metal ratio close to the integral composition Nb6C5. The ordering, which gives rise to superlattice and domain structures similar to those observed in V6C5, appears, however, only in samples that have been cooled slowly through the order-disorder temperature of 1025 C. In TaC of similar composition, the ordering, although present, remains very imperfect even after the crystals are subjected to the same thermal treatment. The results are interpreted in terms of the electronic structure of the transition metal carbides as it is currently understood, and their relevance to the mechanical properties of NbC and TaC are discussed.

  9. Construction and Identification of Plasmid pTA-TUB2

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    An about 1.40 Kb target gene fragment was yielded by PCR amplification with the plasmid pRB 129,which was identified by restriction enzyme digestion that the PCR product was TU B2 gene.The gene was digested by the restriction enzyme and was linked with pTA plasmid to construct pTA-TU B2 plasmid.The plasmid was transformed into Chaetomium spp.by PEG method and the transformation rate was 27/(2×105) and it is nine times higher than that of pRB 129.The transformants can grow on the PDA containing 1 000 μg*mL-1 carbendazim,which is 1 000 times higher than the original Chaetomium spp.The resistance was stable after 10 times transfer on non-selective medium.

  10. CoTaZr/Pd multilayer with perpendicular magnetic anisotropy

    Directory of Open Access Journals (Sweden)

    Yong Chang Lau

    2013-08-01

    Full Text Available We report a novel perpendicularly magnetized thin film [Co91.5Ta4.5Zr4/Pd]5 multilayer, which exhibits strong perpendicular magnetic anisotropy when grown on 5 nm of Pd and Ru seed layers. The Pd-seeded multilayer annealed at 300 °C shows an effective uniaxial anisotropy constant, Keff = 1.1 MJ m−3, with an anisotropy field as high as 1.6 T. The perpendicular anisotropy is sustained on annealing at 400 °C for 1 h. X-ray diffraction on multilayers with 30 repeats suggests that the use of amorphous CoTaZr reduces the stress of the stack, compared to [Co/Pd] multilayer.

  11. HBx M130K and V131I (T-A mutations in HBV genotype F during a follow-up study in chronic carriers

    Directory of Open Access Journals (Sweden)

    Albertazzi Federico

    2005-08-01

    Full Text Available Abstract Background Around 400 million people worldwide are chronically infected with Hepatitis B virus (HBV. An estimated 10% of these chronic patients develop progressive liver damage including cirrhosis and Hepatocellular Carcinoma (HCC. The HBx gene encodes a protein of 154 amino acids which is a transactivator and has been associated with HBV pathogenesis. A change in the amino acid sequences at positions 130 and 131 in the HBV-X protein (M130K and V131I produced by T-A point mutations at the nucleic acids level has been associated with severe liver damage and HCC in patients from China and Africa. Further, such changes have been proposed as a prognostic marker for progressive liver damage and HCC. The purpose of this study was to determine if T-A mutations are present in HBV chronic carriers with genotype F (the major genotype in Costa Rica and further, if these mutations are associated with HBV disease progression in Costa Rica HBV patients from 1972 to 1985. Results Serum samples from 50 HBV positive individuals were amplified and directly sequenced, 48 belonged to genotype F, 1 from genotype D and another was classified as D or E. T-;A mutations were absent in 17 acute patients who recovered, but was present in 12 of 29 chronic carrier samples (42.8%, in one sample the T-A mutations were detected as early as 29 days after clinical onset of disease. In 17 carriers with available liver biopsies, T-;A mutations were found in 8 sera of 13 (61.5% classified as moderate or severe, and none in 4 biopsies with mild liver damage. However, it was not possible to demonstrate a statistical association between the presence of T-A mutations and moderate/severe liver damage, using a Fischer exact test, 1 tail, p = 0.05. In 4 patients HCC was diagnosed, and 2 of them presented the T-A mutations in their sera. Conclusion T-A mutations were found in HBV genotype F in chronic carriers but not in patients who recovered from acute infection. These mutations

  12. Issues for reuse of gloveboxes at LANL TA-55

    Energy Technology Data Exchange (ETDEWEB)

    Cadwallader, L.C.; Pinson, P.A.; Miller, C.F.

    1998-08-01

    This report is a summary of issues that face plutonium glovebox designers and users at the Los Alamos National Laboratory (LANL) Technical Area 55 (TA-55). Characterizing the issues is a step in the task of enhancing the next generation glovebox design to minimize waste streams while providing the other design functions. This report gives an initial assessment of eight important design and operation issues that can benefit from waste minimization.

  13. Due testimonianze di Josip Vaništa

    Directory of Open Access Journals (Sweden)

    Radmila Iva Janković

    2013-12-01

    Full Text Available Radmila Iva Janković ha intervistato nel luglio 2013 Josip Vaništa, artista che aveva partecipato al gruppo Gorgona e preso parte alla residenza d'artista a Brunnenburg nel 1991, organizzata da Francesco Conz con l'obiettivo di includere il gruppo di artisti nel progetto La Livre, una monumentale edizione d'artista dedicata a Ezra Pound.

  14. TaN resistor process development and integration.

    Energy Technology Data Exchange (ETDEWEB)

    Romero, Kathleen (LMATA, Albuquerque, NM); Martinez, Marino John; Clevenger, Jascinda; Austin, Franklin H., IV (, LMATA, Albuquerque, NM); Sullivan, Charles Thomas; Wolfley, Steven L.; Patrizi, Gary A.; Vigil, Pablita S. (LMATA, Albuquerque, NM); Grine, Alejandro J.

    2010-05-01

    This paper describes the development and implementation of an integrated resistor process based on reactively sputtered tantalum nitride. Image reversal lithography was shown to be a superior method for liftoff patterning of these films. The results of a response surface DOE for the sputter deposition of the films are discussed. Several approaches to stabilization baking were examined and the advantages of the hot plate method are shown. In support of a new capability to produce special-purpose HBT-based Small-Scale Integrated Circuits (SSICs), we developed our existing TaN resistor process, designed for research prototyping, into one with greater maturity and robustness. Included in this work was the migration of our TaN deposition process from a research-oriented tool to a tool more suitable for production. Also included was implementation and optimization of a liftoff process for the sputtered TaN to avoid the complicating effects of subtractive etching over potentially sensitive surfaces. Finally, the method and conditions for stabilization baking of the resistors was experimentally determined to complete the full implementation of the resistor module. Much of the work to be described involves the migration between sputter deposition tools - from a Kurt J. Lesker CMS-18 to a Denton Discovery 550. Though they use nominally the same deposition technique (reactive sputtering of Ta with N{sup +} in a RF-excited Ar plasma), they differ substantially in their design and produce clearly different results in terms of resistivity, conformity of the film and the difference between as-deposited and stabilized films. We will describe the design of and results from the design of experiments (DOE)-based method of process optimization on the new tool and compare this to what had been used on the old tool.

  15. TA53:19 Reverb Chamber Quick-Look

    Energy Technology Data Exchange (ETDEWEB)

    Bishofberger, Kip A. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-05-19

    Within Building 19 of TA-53, a screen room has been evaluated for use as a reverb chamber (with deep gratitude to Dale Dalmas and Greg Dale for their assistance). With minimal additional sealing of the chamber, we expect the Q to increase even more, and thus field levels for the same RF source power. Future studies need to determine leakage field levels, which will define maximum achievable field levels.

  16. Proton induced fission of 181-Ta at relativistic energies

    CERN Document Server

    Ayyad, Y; Casarejos, E; Álvarez-Pol, H; Bacquias, A; Boudard, A; Caamaño, M; Enqvist, T; Föhr, V; Kelić-Heil, A; Kezzar, K; Leray, S; Paradela, C; Pérez-Loureiro, D; Pleskač, R; Tarrío, D

    2012-01-01

    Total fission cross sections of 181-Ta induced by protons at different relativistic energies have been measured at GSI, Darmstadt. The inverse kinematics technique used together with a dedicated set-up, made it possible to determine these cross sections with high accuracy. The new data obtained in this experiment will contribute to the understanding of the fission process at high excitation energies. The results are compared with data from previous experiments and systematics for proton-induced fission cross sections.

  17. Issues for reuse of gloveboxes at LANL TA-55

    Energy Technology Data Exchange (ETDEWEB)

    Cadwallader, L.C.; Pinson, P.A.; Miller, C.F.

    1998-08-01

    This report is a summary of issues that face plutonium glovebox designers and users at the Los Alamos National Laboratory (LANL) Technical Area 55 (TA-55). Characterizing the issues is a step in the task of enhancing the next generation glovebox design to minimize waste streams while providing the other design functions. This report gives an initial assessment of eight important design and operation issues that can benefit from waste minimization.

  18. MCrA1Y/TaC Metal Matrix Composite Coatings Produced by Electrospark Deposition

    Institute of Scientific and Technical Information of China (English)

    Yujiang XIE; Yanhong YANG; Mingsheng WANG; Jian HOU

    2013-01-01

    MCrAlY/TaC metal matrix composite coatings with 10,20 and 30 wt.% TaC have been successfully produced by electrospark deposition (ESD).The effects of TaC content on microstructure,hardness and oxidation behavior of the composite coatings were studied.The results showed that the composite coatings were composed of superfine γ columnar dendrite and large TaC particles dispersedly distributed.The hardness was enhanced but oxidation resistance of the composite coatings was reduced with increasing TaC contents.

  19. Seismic assessment of Technical Area V (TA-V).

    Energy Technology Data Exchange (ETDEWEB)

    Medrano, Carlos S.

    2014-03-01

    The Technical Area V (TA-V) Seismic Assessment Report was commissioned as part of Sandia National Laboratories (SNL) Self Assessment Requirement per DOE O 414.1, Quality Assurance, for seismic impact on existing facilities at Technical Area-V (TA-V). SNL TA-V facilities are located on an existing Uniform Building Code (UBC) Seismic Zone IIB Site within the physical boundary of the Kirtland Air Force Base (KAFB). The document delineates a summary of the existing facilities with their safety-significant structure, system and components, identifies DOE Guidance, conceptual framework, past assessments and the present Geological and Seismic conditions. Building upon the past information and the evolution of the new seismic design criteria, the document discusses the potential impact of the new standards and provides recommendations based upon the current International Building Code (IBC) per DOE O 420.1B, Facility Safety and DOE G 420.1-2, Guide for the Mitigation of Natural Phenomena Hazards for DOE Nuclear Facilities and Non-Nuclear Facilities.

  20. Alkane metathesis with the tantalum methylidene [(≡SiO)Ta(=CH2)Me2]/[(≡SiO)2Ta(=CH2)Me] generated from well-defined surface organometallic complex [(≡SiO)TaVMe4

    KAUST Repository

    Chen, Yin

    2015-01-21

    By grafting TaMe5 on Aerosil700, a stable, well-defined, silica-supported tetramethyl tantalum(V) complex, [(≡SiO)TaMe4], is obtained on the silica surface. After thermal treatment at 150 °C, the complex is transformed into two surface tantalum methylidenes, [(≡SiO)2Ta(=CH2)Me] and [(≡SiO)Ta(=CH2)Me2], which are active in alkane metathesis and comparable to the previously reported [(≡SiO)2TaHx]. Here we present the first experimental study to isolate and identify a surface tantalum carbene as the intermediate in alkane metathesis. A systematic experimental study reveals a new reasonable pathway for this reaction.

  1. Technical Area V (TA-V) transformation project close-out report.

    Energy Technology Data Exchange (ETDEWEB)

    2010-07-01

    Sandia National Laboratories (SNL) Technical Area V (TA-V) has provided unique nuclear experimental environments for decades. The technologies tested in TA-V facilities have furthered the United States Nuclear Weapons program and has contributed to the national energy and homeland security mission. The importance of TA-V working efficiently to produce an attractive and effective platform for experiments should not be underestimated. Throughout its brief history, TA-V has evolved to address multiple and diverse sets of requirements. These requirements evolved over many years; however, the requirements had not been managed nor communicated comprehensively or effectively. A series of programmatic findings over several years of external audits was evidence of this downfall. Today, these same requirements flow down through a new TA-V management system that produces consistently applied and reproducible approaches to work practices. In 2008, the TA-V department managers assessed the state of TA-V services and work activities to understand how to improve customer interfaces, stakeholders perceptions, and workforce efficiencies. The TA-V management team initiated the TA-V Transformation Project after they deemed the pre-June 2008 operational model to be ineffective in managing work and in providing integrated, continuous improvement to TA-V processes. This report summarizes the TA-V Transformation Project goals, activities, and accomplishments.

  2. Diffusion barrier performance of nanoscale TaNx thin-film

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    TaNx nanoscale thin-films and Cu/TaNx multilayer structures were deposited on P-type Si(100) substrates by DC reactive magnetron sputtering. The characteristics of TaNx films and thermal stabilities of Cu/TaNx/Si systems annealed at various temperatures were studied by four-point probe(FPP) sheet resistance measurement, atomic force microscopy(AFM), scanning electron microscope-energy dispersive spectrum (SEM-EDS), Alpha-Step IQ Profilers and X-ray diffraction(XRD), respectively. The results show that the surfaces of deposited TaNx thin-films are smooth. With the increasing of N2 partial pressure, the deposition rate and root-mean-square(RMS) decrease, while the content of N and sheet resistance of the TaNx thin-films increase, and the diffusion barrier properties of TaNx thin-films is improved. TaN1.09 can prevent interdiffusion between Cu and Si effectively after annealing up to 650 ℃ for 60 s. The failure of TaNx is mainly attributed to the formation of Cu3Si on TaN/Si interface, which results from Cu diffusion along the grain boundaries of polycrystalline TaN.

  3. Growth and Holographic Storage Properties of Fe:LiTaO3 Crystal

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Using Si-Mo bar as heater and doping Fe2O3 in LiTaO3, Fe∶LiTaO3 crystal was grown by Czochralski method. The curie temperature of the crystal was measured by thermal analyze method. The lattice constants of the crystal were calculated by measuring of X-ray spectra. The response time, exponential gain coefficient and diffraction efficiency of Fe:LiTaO3 were obtained by two wave coupled technique. Compared with Fe∶LiNbO3, the response time of Fe:LiTaO3 is six times shorter, the storage time of Fe:LiTaO3 is ten times longer and the photo scattering resistance ability of Fe:LiTaO3 is four times higher. Fe:LiTaO3 is an excellent holographic storage material.

  4. Synthesis and Optical Properties of NuTaN2: Potential Solar Cell Applications

    Energy Technology Data Exchange (ETDEWEB)

    Yang, M.; Zakutayev, A.; Zhang, X.; Ginley, D.; DiSalvo, F.

    2013-01-01

    Layered CuTaN2 was synthesized by an ion exchange reaction of CuI and NaTaN2 as previously reported. Based on the results of EDX analysis, the Cu:Ta ratio of the CuTaN2 sample was 1:1 within the overall errors when examining powders of +/-10% and no Na was detected. The crystal structure and thermal stability of CuTaN2 was accurately determined by Rietveld analysis of the powder X-ray Diffraction profile and by TGA analysis, respectively. CuTaN2 crystallizes in a rhombohedral structure with space group R-3mH as shown in [figure 1]. CuTaN2 possesses a band gap of 1.53(x) eV, which is in reasonable agreement with density functional theory calculations of Cu containing nitrides. Similar materials may be even better suited for solar cell application.

  5. Preparasi dan karakterisasi fotokatalis NaTaO3 didoping ion lantanum (La/NaTaO3 dengan metode sol-gel

    Directory of Open Access Journals (Sweden)

    Husni Husin

    2011-12-01

    Full Text Available Crystalline sodium tantalate doped with La3+ ions (La/NaTaO3 has been successfully synthesized by sol-gel technique. The photocatalysts have been prepared by mixing of TaCl5, NaOH, and La(NO33.2H2O in the aqueous solution of H2O2. The resulting materials are characterized by X-ray diffraction (XRD, Brunauer-Emmett-Teller (BET, and transmission electron microscopy (TEM to provide useful information about crystallinity and morphology. All samples are exactly indexed as the pure NaTaO3 orthorhombic structure with the space group Pcmn. The XRD spectra displayed a single-phase NaTaO3 structure without any impurity phase, suggesting that lanthanum is uniformly incorporated into the NaTaO3 lattice. TEM images indicates that the particle sizes of the La-doped NaTaO3 powders are approximately 30-80 nm, while the particle sizes of the non-doped NaTaO3 are around 80-250 nm. Doping lanthanum in the NaTaO3 is able to prevent agglomeration, result in particle size, and better crystallinity. The La/NaTaO3 crystal structures reveal that a certain amount of lattice distortion due to the La3+ ions occupying the Na+ sites results in the increase of crystallite size. Powder formation mechanisms for both non-doped NaTaO3 and La-doped NaTaO3 are proposed based on the experimental results. Keywords: La-doped sodium tantalum oxide, photocatalyst, sol-gel, perovskite, orthorhombic

  6. Gold nanoparticles embedded in Ta 2 O 5 /Ta 3 N 5 as active visible-light plasmonic photocatalysts for solar hydrogen evolution

    KAUST Repository

    Luo, Yujing

    2014-07-10

    Here, we demonstrate a new recreating photocatalytic activity of a Nano Au/Ta2O5 composite for hydrogen evolution from water as a visible-light-responsive plasmonic photocatalyst by embedding Au nanoparticles in a Ta2O5 host lattice. The Nano Au/Ta2O 5 composite samples were prepared through a simple Pechini-type sol-gel process. Further nitridating Nano Au/Ta2O5 composite samples in ammonia flow at 1123 K yielded Nano Au/Ta3N 5 composite samples. The obtained Nano Au/Ta3N5 composite exhibited a significantly enhanced photocatalytic activity in the visible region for hydrogen evolution from water compared with blank Ta 3N5 nanoparticles. UV-visible diffuse reflectance spectra and photocatalytic activity measurements indicated that the excitation of surface plasmon resonance of Au nanoparticles is responsible for the new recreating photocatalytic activity of the Nano Au/Ta2O5 composite and significantly enhanced photocatalytic activity of the Nano Au/Ta3N5 composite for hydrogen evolution in the visible region, which might be ascribed to the charge transfer effect in Nano Au/Ta 2O5 composite and the synergetic effect of charge transfer and near-field electromagnetic effect in Nano Au/Ta3N5 composite induced by surface plasmon resonance of embedded Au nanoparticles. The current study could provide a new paradigm for designing plasmonic metal/semiconductor composite systems for photocatalytic, photovoltaic and other optoelectronic devices. © the Partner Organisations 2014.

  7. Mechanical Properties and Electronic Structure of N and Ta Doped TiC: A First-Principles Study

    Science.gov (United States)

    Ma, Shi-Qing; Liu, Ying; Ye, Jin-Wen; Wang, Bin

    2014-12-01

    The first principles calculations based on density functional theory (DFT) are employed to investigate the mechanical properties and electronic structure of N and Ta doped TiC. The result shows that the co-doping of nitrogen and tantalum dilates the lattice constant and improves the stability of TiC. Nitrogen and tantalum can signiβcantly enhance the elastic constants and elastic moduli of TiC. The results of B/G and C12-C44 indicate tantalum can markedly increase the ductility of TiC. The electronic structure is calculated to describe the bonding characteristic, which revealed the strong hybridization between C-p and Ta-d and between N-p and Ti-d. The hardnessis is estimated by a semi-empirical model that is based on the Mulliken overlap population and bond length. While the weakest bond takes determinative role of the hardness of materials, the addition of Ta sharply reduces the hardness of TiC.

  8. Photoelectrochemical evidence of nitrogen incorporation during anodizing sputtering--deposited Al-Ta alloys.

    Science.gov (United States)

    Zaffora, A; Santamaria, M; Di Franco, F; Habazaki, H; Di Quarto, F

    2016-01-01

    Anodic films were grown to 20 V on sputtering-deposited Al-Ta alloys in ammonium biborate and borate buffer solutions. According to glow discharge optical emission spectroscopy, anodizing in ammonium containing solution leads to the formation of N containing anodic layers. Impedance measurements did not evidence significant differences between the dielectric properties of the anodic films as a function of the anodizing electrolyte. Photoelectrochemical investigation allowed evidencing that N incorporation induces a red-shift in the light absorption threshold of the films due to the formation of allowed localized states inside their mobility gap. The estimated Fowler threshold for the internal photoemission processes of electrons resulted to be independent of the anodizing electrolyte confirming that N incorporation does not appreciably affect the density of states distribution close to the conduction band mobility edge. The transport of photogenerated carriers has been rationalized according to the Pai-Enck model of geminate recombination.

  9. Facile and efficient synthesis of the surface tantalum hydride (≡SiO)2TaIIIH and tris-siloxy tantalum (≡SiO)3TaIII starting from novel tantalum surface species (≡SiO)TaMe4 and (≡SiO)2TaMe 3

    KAUST Repository

    Chen, Yin

    2014-03-10

    By grafting of TaMe5 (1) on the surface of silica partially dehydroxylated at 500 C (silica500), a mixture of (≡SiO)TaMe4 (2a; major, 65 ± 5%) and (≡SiO) 2TaMe3 (2b; minor, 35 ± 5%) was produced, which has been characterized by microanalysis, IR, and SS NMR (1H, 13C, 1H-13C HETCOR, proton double and triple quantum). After grafting, these surface organometallic compounds are more stable than the precursor TaMe5. Treatment of 2a,b with water and H 2 resulted in the formation of methane in amount of 3.6 ± 0.2 and 3.4 ± 0.2 mol/grafted Ta, respectively. 2a,b react with H2 (800 mbar) to form (≡SiO)2TaH. After (≡SiO) 2TaH was heated to 500 C under hydrogen or vacuum, [(≡SiO) 3Ta][≡SiH] was produced, and the structure was confirmed by IR, NMR, and EXAFS. Considering the difficulty of the previous preparation method, these syntheses represent a facile and convenient way to prepare tantalum surface species (≡SiO)2TaH and (≡SiO)3Ta via the intermediate of the new surface organometallic precursors: (≡SiO)TaMe4/(≡SiO)2TaMe3. (≡SiO)2TaH and (≡SiO)3Ta exhibit equal reactivities in alkane metathesis and ethylene polymerization in comparison to those in previous reports. © 2014 American Chemical Society.

  10. Superelastic and shape memory properties of TixNb3Zr2Ta alloys.

    Science.gov (United States)

    Zhu, Yongfeng; Wang, Liqiang; Wang, Minmin; Liu, Zhongtang; Qin, Jining; Zhang, Di; Lu, Weijie

    2012-08-01

    The microstructure and phase constitutions of TixNb3Zr2Ta alloys (x=35, 31, 27, 23) (wt%) were studied. With a lower niobium content the grain size of β phase in TixNb3Zr2Ta alloys increased significantly, and the TixNb3Zr2Ta system was more likely to form α″ phase and even α phase. Tensile tests showed that UTS of TixNb3Zr2Ta alloys improved as the Nb content was decreased. Cyclic loading-unloading tensile tests were carried on TixNb3Zr2Ta alloys. Ti23Nb3Zr2Ta and Ti27Nb3Zr2Ta alloys featured the best superelasticity among the alloys studied. The pseudoelastic strain ratio of Ti35Nb3Zr2Ta alloy decreased a lot as the cycle number increased. Ti31Nb3Zr2Ta alloy showed only minimum superelasticity. This is because Ti23Nb3Zr2Ta and Ti27Nb3Zr2Ta alloys had higher yield strength than Ti31Nb3Zr2Ta did, which allowed martensite phase to be induced. On the contrary, Ti31Nb3Zr2Ta alloy exhibited better shape memory property than Ti27Nb3Zr2Ta, Ti23Nb3Zr2Ta and Ti35Nb3Zr2Ta titanium alloys. β phase, α phase and α″ phase were found in Ti23Nb3Zr2Ta alloy by TEM observation. The dislocation density of α phase was much lower than that of β phase due to their crystal structure difference. This may explained why Ti23Nb3Zr2Ta with α phase possessed higher tensile strength. The incomplete shape recovery of Ti23Nb3Zr2Ta alloy after unloading resulted from two sources. Plastic deformation occurred in β phase, α phase and even α″ phase under dislocation slip mechanism, and incomplete decomposition of α″ martensitic phase resulted in unrecovered strain as well. Copyright © 2012 Elsevier Ltd. All rights reserved.

  11. Roles of TaON and Ta{sub 3}N{sub 5} in the visible-Fenton-like degradation of atrazine

    Energy Technology Data Exchange (ETDEWEB)

    Du, Yingxun, E-mail: yxdu@niglas.ac.cn; Zhao, Lu; Zhang, Yuanyuan

    2014-02-01

    Graphical abstract: - Highlights: • TaON exhibited higher photocatalytic activity than Ta{sub 3}N{sub 5}. • e{sub CB} is captured by either Fe{sup 3+} or H{sub 2}O{sub 2} and h{sub VB} could not oxidize atrazine. • ·OH, from the reduction of H{sub 2}O{sub 2} by Fe{sup 2+} or by e{sub CB}, is the active species. • By capturing e{sub CB}, H{sub 2}O{sub 2} was preferred to be reduced to H{sub 2}O than to ·OH. • TaON showed the higher separation efficiency of electrons and holes than Ta{sub 3}N{sub 5}. - Abstract: In this study, the roles of TaON and Ta{sub 3}N{sub 5} in the degradation of atrazine by the visible-Fenton-like system were examined in detail. The TaON and Ta{sub 3}N{sub 5} samples prepared by the nitridation of Ta{sub 2}O{sub 5} and characterized by XRD, DRS, BET and PL analyses. The results showed that the TaON sample had weaker absorption in the visible region but higher specific surface area than the Ta{sub 3}N{sub 5} sample. The degradation rate of atrazine in visible-TaON-Fenton-like system was 2.64 times than that in visible-Ta{sub 3}N{sub 5}-Fenton-like system. Both Fe{sup 2+} and H{sub 2}O{sub 2} could be reduced by e{sub CB} (electrons in the conduction band) in TaON or Ta{sub 3}N{sub 5}, while atrazine could not be oxidized by h{sub VB} (holes in the valance band). ·OH is the active species for the degradation of atrazine in visible-TaON/Ta{sub 3}N{sub 5}-Fenton-like systems. Majority of ·OH originated from Fenton reaction. After Fe{sup 3+} was reduced by e{sub CB} to Fe{sup 2+}, Fe{sup 2+} reacted quickly with H{sub 2}O{sub 2} to generate ·OH. In addition, by capturing e{sub CB}, a little of H{sub 2}O{sub 2} was reduced to yield ·OH, which contributed a small fraction of atrazine degradation. Based on the experimental results, the roles of TaON and Ta{sub 3}N{sub 5} in the visible-Fenton-like system were proposed. And the higher photocatalytic activity of TaON than Ta{sub 3}N{sub 5} was suggested to be due to the higher

  12. Structure of metal-oxide Ti-Ta-(Ti,Ta)xOy coatings during spark alloying and induction-thermal oxidation

    Science.gov (United States)

    Koshuro, V.; Fomin, A.; Fomina, M.; Rodionov, I.; Brzhozovskii, B.; Martynov, V.; Zakharevich, A.; Aman, A.; Oseev, A.; Majcherek, S.; Hirsch, S.

    2016-08-01

    The study focuses on combined spark alloying of titanium and titanium alloy surface and porous matrix structure oxidation. The metal-oxide coatings morphology is the result of melt drop transfer, heat treatment, and oxidation. The study establishes the influence of technological regimes of alloying and oxidation on morphological heterogeneity of metal- oxide system Ti-Ta-(Ti,Ta)xOy.

  13. From Ba3Ta5O14N to LaBa2Ta5O13N2: Decreasing the optical band gap of a photocatalyst

    Science.gov (United States)

    Anke, B.; Bredow, T.; Pilarski, M.; Wark, M.; Lerch, M.

    2017-02-01

    Yellow LaBa2Ta5O13N2 was successfully synthesized as phase-pure material crystallizing isostructurally to previously reported Ba3Ta5O14N and mixed-valence Ba3TaV4TaIVO15. The electronic structure of LaBa2Ta5O13N2 was studied theoretically with the range-separated hybrid method HSE06. The most stable structure was obtained when lanthanum was placed on 2a and nitrogen on 4h sites confirming Pauling's second rule. By incorporating nitrogen, the measured band gap decreases from ∼3.8 eV for the oxide via 2.74 eV for Ba3Ta5O14N to 2.63 eV for the new oxide nitride, giving rise to an absorption band well in the visible-light region. Calculated fundamental band gaps confirm the experimental trend. The atom-projected density of states has large contributions from N2p orbitals close to the valence band edge. These are responsible for the observed band gap reduction. Photocatalytic hydrogen formation was investigated and compared with that of Ba3Ta5O14N revealing significantly higher activity for LaBa2Ta5O13N2 under UV-light.

  14. Partitioning and Hydrolysis of Nb and Ta and Their Implications with Regard to Mineralization

    Institute of Scientific and Technical Information of China (English)

    王玉荣; 顾复; 等

    1993-01-01

    K2NbOF5·H2O and K2TaF7 were prepared through melting Nb2O5 and Ta2O5 respectively with FHF2·2H2O, followed by recrystallizing .The hydrolysis properties of K2NbOF5 and K2TaF7 were determined again by using a rapidly quench vessel.As temperature (from 250 to 550℃) and pressure (from 500 to 1500 bars) increase, the degree of hydrolysis of both K2NbOF5 and K2TaF7 will increase.Nb- and Ta-fluorine complex compounds are instable in supercritical aqueous fluids.The degree of hydrolysis of both K2NbOF5 and K2TaF7 decreases with increasing concentra-tion of HF, independent of the concentration of NaF .The partition coefficients of Nb and Ta between granitic melt and fluid phase are less than 0.15,ie., most of Nb and Ta are left in granitic melt.The partition coefficient of Ta is more dependent on the concentration of HF than that of Nb.The significance of hydrolysis in Nb-ans Ta mineralization is also discussed in the present paper.

  15. [Cl5Ta(μ-O)TaCl3{(i)PrS(CH2)2S(i)Pr}] and [(TaCl4)2(μ-O)(μ-Me2Se2)]: two chalcogenoether complexes of Ta2OCl8 with very different geometries.

    Science.gov (United States)

    Benjamin, Sophie L; Hyslop, Alison; Levason, William; Webster, Michael

    2011-07-01

    The title compounds, [1,2-bis(isopropylsulfanyl)ethane-2κ(2)S,S']octachlorido-1κ(5)Cl,2κ(3)Cl-μ-oxido-ditantalum(V), [Ta(2)Cl(8)O(C(8)H(18)S(2))], (I), and μ-dimethyldiselane-κ(2)Se:Se'-μ-oxido-bis[tetrachloridotantalum(V)], [Ta(2)Cl(8)O(C(2)H(6)Se(2))], (II), contain six-coordinate Ta(V) centres linked by a nonlinear oxide bridge. Compound (I) contains one Ta(V) centre bonded to a chelating dithioether and three terminal chloride ligands, with the second Ta(V) centre bonded to five terminal chloride ligands. In (II), two tetrachloridotantalum(V) residues are bridged by the diselenide, giving a puckered five-membered Ta/O/Ta/Se/Se ring. The Ta-O distances in the bridges are short in both compounds, indicating that significant multiple-bond character is retained despite the deviation from linearity, and the bond lengths reveal a clear trans influence order of O > Cl > S > Se on the hard Ta(V) centre. The structures are compared with the [Ta(2)Cl(10)O](2-) anion, which contains a linear oxide bridge.

  16. Removal of organic matter from H2TaF7 solution by adsorption

    Institute of Scientific and Technical Information of China (English)

    LI Qing-gang; ZHOU Kang-gen; ZHANG Qi-xiu

    2005-01-01

    The removal of organic matter from H2TaF7 solution by adsorption was investigated in order to reduce the carbon content in the K2TaF7 crystal. Three kinds of adsorbent, LSA-5 resin, LSA-20 resin and active carbon were applied in the fixed bed respectively. Experimental results indicate that LAS-5 resin, LAS-20 resin, the mixture of LAS-5 resin and LAS-20 resin(with volume ratio of 1∶1), and the active carbon can all reduce chemical oxygen demand(COD) value of the H2TaF7 solution, and reduce consequently carbon content of K2TaF7 crystal to 0.001 0%0.001 5% from 0.002 5%0.003 0%. Comparing with the others, the active carbon is an approved adsorbent whose bed volumes of effluent reaches 70. In addition, there is a linear relationship between the COD value of H2TaF7 solution and the carbon content in K2TaF7 crystal, and the carbon content in K2TaF7 crystal decreases with the decreasing of COD value of H2TaF7 solution. When the COD value of H2TaF7 solution is lower than 7 mg/L, the carbon content in K2TaF7 crystal would decrease to less than 0.001 5%.

  17. XPS analyses of Ta/MgO{sub x}/Ni{sub 81}Fe{sub 19}/MgO{sub x}/Ta films

    Energy Technology Data Exchange (ETDEWEB)

    Li Minghua, E-mail: mhli@ustb.edu.cn [Department of Material Physics and Chemistry, University of Science and Technology Beijing, Beijing 100083 (China); Han Gang; Liu Yang; Feng Chun; Wang Haicheng; Teng Jiao; Yu Guanghua [Department of Material Physics and Chemistry, University of Science and Technology Beijing, Beijing 100083 (China)

    2012-10-01

    Highlights: Black-Right-Pointing-Pointer Ta/MgO{sub x}/Ni{sub 81}Fe{sub 19}/MgO{sub x}/Ta films were prepared by magnetron sputtering. The anisotropic magnetoresistance (AMR) increases dramatically after annealing. Black-Right-Pointing-Pointer The chemical states of Ta and MgO{sub x} at the interface of the NiFe/MgO{sub x}/Ta films, which were prepared at the different technological conditions, were analyzed by X-ray photoelectron spectroscopy (XPS). Black-Right-Pointing-Pointer The AMR of Ta/MgO{sub x}/Ni{sub 81}Fe{sub 19}/MgO{sub x}/Ta films is related to the chemical states of MgO{sub x}. These states were produced under different technical conditions and influence the film properties. - Abstract: Ta/MgO{sub x}/Ni{sub 81}Fe{sub 19}/MgO{sub x}/Ta films were prepared by magnetron sputtering. The anisotropic magnetoresistance (AMR) increases dramatically after annealing. The chemical states of Ta and MgO{sub x} at the interface of the NiFe/MgO{sub x}/Ta films, which were prepared at the different technological conditions, were analyzed by X-ray photoelectron spectroscopy (XPS). The results show that the AMR of the films is related to the chemical states of MgO{sub x}. The chemical states of Mg are different when MgO{sub x} is prepared at different technological conditions. Therefore, increasing the AMR is beneficial when more Mg{sup 2+} ions are present in the MgO{sub x} films.

  18. A Monte Carlo simulation of radiative transfer in the atmosphere applied to ToTaL-DOAS

    Science.gov (United States)

    Premuda, M.; Masieri, S.; Bortoli, D.; Margelli, F.; Ravegnani, F.; Petritoli, A.; Kostadinov, I.; Giovanelli, G.; Cupini, E.

    2009-09-01

    In the frame of DOAS, a Monte Carlo code has been developed, to calculate, for a given detector with assigned diameter and field of view, the single and multiple scattering radiance. Very general 3-D geometry is foreseen. Spatial distribution along the detector axis for the single and total scattering radiance are computed. Ground reflected contributions to the solar radiance are estimated. Differential effects due to small perturbations in physical parameters, such as ozone density, can simultaneously be taken into account in the same calculation. The code has been applied to ToTaL-DOAS (Topographic Target Light scattering-Differential Optical Absorption Spectroscopy) measurements.

  19. Quantum and superconducting fluctuations effects in disordered Nb 1- xTa x thin films above Tc

    Science.gov (United States)

    Giannouri, M.; Papastaikoudis, C.

    1999-05-01

    Disordered Nb 1- xTa x thin films are prepared with e-gun coevaporation. The influence of the β-phase of tantalum in the critical temperature Tc is observed as a function of the substrate temperature. The measurements of transverse magnetoresistance at various isothermals are interpreted in terms of weak-localization and superconducting fluctuations. From the fitting procedure, the phase breaking rate τφ-1 and the Larkin parameter βL are estimated as a function of temperature. Conclusions about the dominant inelastic scattering mechanisms at various temperature regions as well as for the dominant mechanism of superconducting fluctuations near the transition temperature are extracted.

  20. Modifications of the heliostat procedures for irradiance estimates from satellite images

    Energy Technology Data Exchange (ETDEWEB)

    Beyer, H.G.; Costanzo, Claudio; Heinemann, Detlev [Oldenburg Univ. (Germany). Fachbereich 8 - Physik

    1996-03-01

    Images taken by geostationary satellites may be used to estimate solar irradiance fluxes at the earth`s surface. The Heliostat method is a widely applied procedure for this task. It is based on the empirical correlation between a satellite derived cloud index and the irradiance at the ground. Modifications to this procedure that may reduce the temporal variability of the correlation are presented. The modified method may open the way to the use of a generic relation of cloud index and global irradiance. (author)

  1. The effects of Cr, Co, Al, Mo and Ta on the cyclic oxidation behavior of a prototype cast Ni-base superalloy based on a 2(5) composite statistically designed experiment

    Science.gov (United States)

    Barrett, C. A.

    1984-01-01

    A series of cast Ni-base superalloys were systematically varied at selected levels of Co, Cr, Mo, Ta, and Al. The elemental levels varied were Mo, 0 to 4 percent; Cr, 6 to 18 percent; Co, 0 to 20 percent, Ta, 0 to 8 percent; and Al, 3.25 to 6.25 percent. The cyclic oxidation resistance was determined from specific weight change data as a function of time for 1 hr cycles in static air at 1100 C. The significant terms in decreasing order of their importance were Al, Ta, Cr2, Al-Cr, Cr-Co, Co2, Al-Mo, Cr-Mo, Al-Al, and Mo-Ta. The Al term alone accounted for close to 82 percent of the explained variability. The estimating equation showed that the Al level was the most important and should be at its 6.25 wt % maximum value. The Mo and Ta levels should also be at their maximum 4 and 8 wt % respectively. The cobalt composition should be as low as possible, i.e., 0 wt%. The Cr level optimum varies depending on the other 4 levels. The X-ray diffaction results indicate the most protective scales are alumina/aluminate spinel stabilizized with a tri-rutile oxide high in Ta and Mo.

  2. Microstructure evolution mechanism in adiabatic shear band in TA2

    Institute of Scientific and Technical Information of China (English)

    杨扬; 熊俊; 杨续跃

    2004-01-01

    The micro structure evolution mechanism in adiabatic shear band in commercial pure titanium (TA2) at high strain rates(γ≈105 - 106/s) were studied. The nanosized recrystallized grains (about 50 nm in diameter) within the center of adiabatic shear band (ASB) were observed by means of transmission electronic microscope (TEM). A Rotational Dynamic Recrystallization (RDR) mechanism can explain the microstructure evolution (i. e. nanosized grains were formed within 5 - 10μs) in ASB. Kinetics calculations indicate that the recrystallized small grains are formed during the deformation and don't undergo significant growth by grain boundary migration after deformation.

  3. TaC Studios New Construction Test House

    Energy Technology Data Exchange (ETDEWEB)

    Butler, T. [NAHB Research Center Industry Partnership, Upper Marlboro, MD (United States); Curtis, O. [NAHB Research Center Industry Partnership, Upper Marlboro, MD (United States); Kim, E. [NAHB Research Center Industry Partnership, Upper Marlboro, MD (United States); Roberts, S. [NAHB Research Center Industry Partnership, Upper Marlboro, MD (United States); Stephenson, R. [NAHB Research Center Industry Partnership, Upper Marlboro, MD (United States)

    2013-03-01

    As part of the NAHB Research Center Industry Partnership, Southface partnered with TaC Studios, an Atlanta based architecture firm specializing in residential and light commercial design, on the construction of a new test home in Atlanta, GA, in the mixed humid climate zone. This home will serve as a model home for the builder partner and addresses Building America energy savings targets through the planning and implementation of a design package will serve as a basis of design for the builder partner’s future homes. As a BA test house, this home will be evaluated to detail whole house energy use, end use loads, and HVAC and hot water efficiency.

  4. TA-54 (Area G) Risk Assessment from Extreme Wildfire Scenarios

    Energy Technology Data Exchange (ETDEWEB)

    Linn, Rodman Ray [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Koo, Eunmo [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Honig, Kristen Ann [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); White, Judith [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Funk, David John [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-08-10

    Los Alamos National Laboratory (LANL) and surrounding areas have been exposed to at least four significant wildfires since 1977 and there have been numerous others within 50 miles of LANL. Based on this history, wildfires are considered a risk to LANL facilities and their contents. While many LANL facilities are at risk to wildfire to some degree, they are found in a wide variety of conditions, thus they have varying sensitivities to wildfires. Additionally, LANL facilities have various functions and different assets, so they have a wide range of values or consequences if compromised. Therefore, determining the risks and precautions that are warranted to mitigate these risks must be done on a case-by-case basis. In an effort to assess possible wildfire risks to sensitive materials stored in a Perma-Con® in dome TA-54-0375, a conventional fire risk analysis was performed. This conventional risk analysis is documented in Engineering Evaluation Form AP-FIRE-001-FM1, which is dated 9/28/2015 and was titled ‘Wildland Fire Exposure Evaluation for Building TA-54-0375’ (Hall 2015). This analysis acknowledged that there was significant chance of wildfire in the vicinity of TA-54-0375, but the amount of combustible material surrounding the building was deemed low. The wildland fuels that were closest to the building were largely fine fuels and were not expected to have significant duration of heat release. The prevailing winds at this location are from the south and southwest and the nearest significant upwind fuels (tree crowns or unmown grasses) are at least 300 feet away. Based on these factors the conventional wildland fire risk to TA-54-0375 was deemed minimal, “Acceptable As Is, No Action Required.” This risk evaluation was based on a combined assessment of low probability of wildfires arriving at the site from other directions (where higher fuel loadings might be present) as well as the effective setback of fuels in the direction that fire is

  5. Symposium in Honour of T.A. Springer

    CERN Document Server

    Hesselink, Wim; Kallen, Wilberd; Strooker, Jan

    1987-01-01

    From 1-4 April 1986 a Symposium on Algebraic Groups was held at the University of Utrecht, The Netherlands, in celebration of the 350th birthday of the University and the 60th of T.A. Springer. Recognized leaders in the field of algebraic groups and related areas gave lectures which covered wide and central areas of mathematics. Though the fourteen papers in this volume are mostly original research contributions, some survey articles are included. Centering on the Symposium subject, such diverse topics are covered as Discrete Subgroups of Lie Groups, Invariant Theory, D-modules, Lie Algebras, Special Functions, Group Actions on Varieties.

  6. Experimental investigation of phase equilibria in the Nb-Si-Ta ternary system

    Energy Technology Data Exchange (ETDEWEB)

    Li, Jian; Wang, Cuiping; Yao, Jun; Yang, Shuiyuan; Zhan Shi; Liu, Xingjun [Xiamen Univ. (China). Dept. of Materials Science and Engineering; Xiamen Univ. (China). Fujian Provincial Key Laboratory of Materials Genome; Kang, Yongwang [Beijing Institute of Aeronautical Materials (China). Science and Technology on Advanced High Temperature Structural Materials Lab.

    2016-12-15

    The phase equilibria in the Nb-Si-Ta ternary system at 1 373 K, 1 473 K and 1 573 K were investigated by means of back-scattered electron imaging, electron probe microanalysis and X-ray diffraction. The isothermal sections at 1 373 K, 1 473 K and 1 573 K consist of two three-phase regions and seven two-phase regions, without any ternary compounds. The compounds of NbSi{sub 2} and TaSi{sub 2}, αNb{sub 5}Si{sub 3} and αTa{sub 5}Si{sub 3} form continuous solid solutions, respectively. The solubilities of Nb in Ta{sub 3}Si and Ta{sub 2}Si phases are extremely large, whereas the solubility of Si in the β(Nb, Ta) phase is relatively small.

  7. Carrier dynamics of a visible-light-responsive Ta3N5 photoanode for water oxidation

    KAUST Repository

    Ziani, Ahmed

    2015-01-01

    The physicochemical properties of a tantalum nitride (Ta3N5) photoanode were investigated in detail to understand the fundamental aspects associated with the photoelectrochemical (PEC) water oxidation. The Ta3N5 thin films were synthesized using DC magnetron sputtering followed by annealing in air and nitridation under ammonia (NH3). A polycrystalline structure with a dense morphology of the monoclinic Ta3N5 films was obtained. A relatively low absorption coefficient (104 to 105 cm-1) in the visible light range was measured for Ta3N5, consistent with the nature of the indirect band-gap. Ultra-fast spectroscopic measurements revealed that the Ta3N5 with different thicknesses films possess low transport properties and fast carrier recombination (<10 ps). These critical kinetic properties of Ta3N5 as a photoanode may necessitate high overpotentials to achieve appreciable photocurrents for water oxidation (onset ∼0.6 V vs. RHE). This journal is

  8. High-density formation of Ta nanodot induced by remote hydrogen plasma

    Science.gov (United States)

    Wang, Yaping; Takeuchi, Daichi; Ohta, Akio; Ikeda, Mitsuhisa; Makihara, Katsunori; Miyazaki, Seiichi

    2017-01-01

    We have studied the formation of Ta nanodots (NDs) on thermally grown SiO2/Si by exposing a thin metal layer to a remote H2 plasma (H2-RP) without external heating. Atomic force microscopy (AFM) analyses show that a combination of a Ge (˜30.0 nm)/Ta (˜2.0 nm) bilayer stack with subsequent H2-RP exposure is effective for forming electrically isolated Ta NDs with an areal dot density as high as ˜1011 cm-2, where the Ge layer plays an important role as a barrier layer against the oxidation of the ultrathin Ta layer surface. The change in the chemical structure of the Ge/Ta bilayer stack on SiO2/Si upon Ta ND formation by H2-RP exposure is investigated by hard X-ray photoemission spectroscopy (HAXPES) and X-ray photoelectron spectroscopy (XPS).

  9. Supporting data for senary refractory high-entropy alloy CrxMoNbTaVW

    Directory of Open Access Journals (Sweden)

    B. Zhang

    2015-12-01

    Full Text Available This data article is related to the research paper entitled “senary refractory high-entropy alloy CrxMoNbTaVW [1]”. In this data article, the pseudo-binary Cr-MoNbTaVW phase diagram is presented to show the impact of Cr content to the senary Cr-MoNbTaVW alloy system; the sub-lattice site fractions are presented to show the disordered property of the Cr-MoNbTaVW BCC structures; the equilibrium and Scheil solidification results with the actual sample elemental compositions are presented to show the thermodynamic information of the melted/solidified CrxMoNbTaVW samples; and the raw EDS scan data of the arc-melted CrxMoNbTaVW samples are also provided.

  10. Collective flows of protons and $\\pi^-$ mesons in $^{2}$H + C, Ta and He plus C, Ta collisions at 3.4 GeV/nucleon

    CERN Document Server

    Chkhaidze, L; Djobava, T; Kladnitskaya, E; Kharkhelauri, L; Uzhinsky, V

    2011-01-01

    Collective flows of protons and negative pions have been studied in (2)H + C, Ta and He + C, Ta collisions at an energy of 3.4 GeV/nucleon. The data have been obtained by the 2-m Propane Bubble Chamber (PBC-500) at JINR. It is found that the directed flow of protons and pi(-) mesons characterized by d /d(y) increases with increase of the mass numbers of colliding nucleus pairs; the elliptic proton flow points out of the reaction plane and also strengthens as the system mass increases; the negative pion directed flow is in the same reaction plane as the proton flow for the lighter (2H + C, He + C) systems and in the opposite direction for the heavier ((2)H + Ta, He + Ta) systems. In (2)H + C, He + C, C + C, C + Ne, (2)H + Ta, He + Ta, C + Cu, and C + Ta collisions, the linear dependence of directed and elliptic flow parameters from mass numbers of projectile and target nuclei, (A(P).A(T))(1/2), is similar for protons while for pi(-) mesons the dependence of directed flow parameters is stronger. The ultrarelati...

  11. Study on Luminescence Properties of High-Density Phosphors BiTaO4∶Pr3+ and BiTaO4

    Institute of Scientific and Technical Information of China (English)

    张庆礼; 郭常新; 施朝淑; 刘波

    2003-01-01

    The photoluminescence properties of BiTaO4∶Pr3+ and BiTaO4 at room temperature were studied, and the infrared transmission and diffusion reflection spectra of BiTaO4 were measured. The photoluminescence spectrum of BiTaO4 peaks at about 420, 440 and 465 nm. There has an obvious excitation band from 330 to 370 nm. The photoluminescence spectrum of BiTaO4∶Pr3+ consists of the characteristic emission of Pr3+, and its main peak is at 606 nm from 3P0→3H6 transition of Pr3+. Its excitation spectrum consists of the wide band with maximum at 325 nm, the wide band in the range of 375~430 nm, and the characteristic excitation of Pr3+. The bands at 325 nm and 375~430 nm may be from the absorption of the charge transfer transition of the tantalate group and defect energy levels in its forbidden band, respectively. There is energy transfer from host to Pr3+. Because both the host density and photoluminescence peak intensity of BiTaO4∶Pr3+ are superior to PbWO4, BiTaO4∶Pr3+ may be a potential heavy scintillator.

  12. Oxidation of TaSi2 thin films on polycrystalline Si

    Science.gov (United States)

    Nguyen Tan, T. A.; Guerfi, N.; Veuillen, J. Y.; Derrien, J.

    1990-01-01

    XPS and UPS have been used for studying the oxidation of TaSi2 films formed by annealing, under ultrahigh-vacuum, of Ta deposits (≈70Å) on polycrystalline Si. Oxidation has been carried out at room-temperature and at 700°C with an oxygen pressure of 2×10-5 mbar. Both Ta and Si react with oxygen. At room-temperature, O chemisorbs on the surface giving a mixed phase of Si suboxides and Ta oxides (TaO, TaO2 and Ta2O5). At 700°C, a very thin Ta2O5 layer (<0.1 monolayer) is formed on top of the growing SiO2 layer. In comparison with Si(111), the oxidation kinetics of TaSi2 begins with a higher transitory rate and follows afterwards the same parabolic dependence of the SiO2 thickness as a function of oxidation time. UPS spectra indicate a higher density of interface states, in comparison with that of SiO2 on Si. The XPS valence band testifies that the electronic structure of the underlying TaSi2 is preserved after oxidation. Subsequent heating of the sample leads to the progressive decomposition of SiO2, at T ≳ 750°C, while the upper Ta2O5 layer is not affected. The results are discussed in relation to thermodynamic properties of Si and Ta oxides, and compared with existing results given by macroscopic methods.

  13. Density Measurement of Liquid Ni-Ta Alloys by a Modified Sessile Drop Method

    Institute of Scientific and Technical Information of China (English)

    FANG Liang; XIAO Feng; TAO Zainan; Kusuhiro Mukai

    2005-01-01

    The density of liquid Ni-Ta alloys was measured by using a modified sessile drop method. It is found that the density of the liquid Ni-Ta alloys decreases with the increasing temperature, but increases with the increase of tantalum concentration in the alloys. The molar volume of liquid Ni-Ta binary alloys increases with the increase of temperature and tantalum concentration.

  14. TaS2 nanosheet-based room-temperature dosage meter for nitric oxide

    Directory of Open Access Journals (Sweden)

    Qiyuan He

    2014-09-01

    Full Text Available A miniature dosage meter for toxic gas is developed based on TaS2 nanosheets, which is capable of indicating the toxic dosage of trace level NO at room temperature. The TaS2 film-based chemiresistor shows an irreversible current response against the exposure of NO. The unique non-recovery characteristic makes the TaS2 film-based device an ideal indicator of total dosage of chronicle exposure.

  15. Characterization of Ta-based barrier films on SiLK for Cu-metalization

    NARCIS (Netherlands)

    Bystrova, S.; Holleman, J.; Woerlee, P.H.; Wolters, R.A.M.

    2002-01-01

    Structures with Ta, TaxN1-x, Ta90C10, Ta95Si5 on SiLK were tested using in-situ 4- point probe resistance measurements during annealing up to 400oC. The change in normalized resistance by a factor of up to 2.58 was attributed to oxygen diffusion out of SiLK layer into the barriers. No direct chemica

  16. H2 evolution on Lanthanum and Carbon co-doped NaTaO3 Photocatalyst

    Directory of Open Access Journals (Sweden)

    Husni Husin

    2014-07-01

    Full Text Available We report a carbon-modify lanthanum doped sodium tantalum oxide powders (La-C-NaTaO3 by sol-gel process. The resultant materials are characterized by powder X-ray diffraction (XRD, scanning electron microscopy (SEM, and transmission electron microscopy (TEM. The X ray diffraction of La-C-NaTaO3 show a single phases with a good crystallinity and without any impurity. The samples is exactly indexed as NaTaO3 monoclinic structure with the space group P2/m. The SEM measurements give a smaller particle size of doped NaTaO3 than pure NaTaO3. The effect of dopant on the photocatalytic activity of La-C-NaTaO3 in the photocatalytic of hydrogen generation is studied and compared with pure NaTaO3. The results show that the rate of hydrogen evolution over La-C-NaTaO3 is higher as compared to that of pure NaTaO3. The enhancement of photocatalytic activity of La-C-NaTaO3 nanocrystalline is mainly due to their capability for reducing the electron hole pair recombination. The La-C-dopant is believed to play a key role in the enhancement of photocatalytic properties of La-C-NaTaO3 crystalline.Submitted: 28th September 2013; Revised: 16th February 2014; Accepted: 28th February 2014[How to Cite: Husin, H., Mahidin, M., Zuhra, Z., Hafita, F. (2014. H2 evolution on Lanthanum and Carbon co-doped NaTaO3 Photocatalyst . Bulletin of Chemical Reaction Engineering & Catalysis, 9 (2:81-86. (doi:10.9767/bcrec.9.2.5530.81-86][Permalink/DOI: http://dx.doi.org/10.9767/bcrec.9.2.5530.81-86] 

  17. Geology of the Western Part of Los Alamos National Laboratory (TA-3 to TA-16), Rio Grande Rift, New Mexico

    Energy Technology Data Exchange (ETDEWEB)

    C.J.Lewis; A.Lavine; S.L.Reneau; J.N.Gardner; R.Channell; C.W.Criswell

    2002-12-01

    We present data that elucidate the stratigraphy, geomorphology, and structure in the western part of Los Alamos National Laboratory between Technical Areas 3 and 16 (TA-3 and TA-16). Data include those gathered by geologic mapping of surficial, post-Bandelier Tuff strata, conventional and high-precision geologic mapping and geochemical analysis of cooling units within the Bandelier Tuff, logging of boreholes and a gas pipeline trench, and structural analysis using profiles, cross sections, structure contour maps, and stereographic projections. This work contributes to an improved understanding of the paleoseismic and geomorphic history of the area, which will aid in future seismic hazard evaluations and other investigations. The study area lies at the base of the main, 120-m (400-ft) high escarpment formed by the Pajarito fault, an active fault of the Rio Grande rift that bounds Los Alamos National Laboratory on the west. Subsidiary fracturing, faulting, and folding associated with the Pajarito fault zone extends at least 1,500 m (5,000 ft) to the east of the main Pajarito fault escarpment. Stratigraphic units in the study area include upper units of the Tshirege Member of the early Pleistocene Bandelier Tuff, early Pleistocene alluvial fan deposits that predate incision of canyons on this part of the Pajarito Plateau, and younger Pleistocene and Holocene alluvium and colluvium that postdate drainage incision. We discriminate four sets of structures in the area between TA-3 and TA-16: (a) north-striking faults and folds that mark the main zone of deformation, including a graben in the central part of the study area; (b) north-northwest-striking fractures and rare faults that bound the eastern side of the principal zone of deformation and may be the surface expression of deep-seated faulting; (c) rare northeast-striking structures near the northern limit of the area associated with the southern end of the Rendija Canyon fault; and (d) several small east

  18. Imaging spectroscopy with Ta/Al DROIDs: performance for different geometries

    Science.gov (United States)

    Hijmering, R. A.; Jerjen, I.; Verhoeve, P.; Martin, D. D. E.; Peacock, A.; Kozorezov, A. G.; Venn, R.

    2006-06-01

    In this paper we present the preliminary results from experiments with Distributed Read Out Imaging Devices (DROIDs) in the optical and in the X-ray regime. For the optical results DROIDs of different lengths ranging from 200 to 700 μm have been used with an STJ lay-up of Ta/Al/AlOx/Al/Ta with thicknesses of 100/30/1/30/100 nm. With this data the behavior with different absorber length has been investigated to determine an optimal absorber size for a DROID array to be used in the optical wavelength regime. The optimum absorber size has been found to be 30x400 um. The X-ray data has been obtained with a similar device structure but with 60 nm aluminium trapping layers to increase the trapping of quasiparticles in the STJs. In this paper we only present the data obtained with the standard DROID size of 400μm. With this device an extensive set of measurements have been performed which involves; a scan in photon energy ranging from 50eV to 1900 eV, a scan in temperature and a scan in bias voltage. We report here only results from the preliminary analysis of the data obtained with readout electronics comprising the normal preamplifier and subsequent shaping stage. For the final analyzes the pulses resulting from the STJs have been digitized and are ready to be analyzed. The pulses have been used to estimate the decay time of the STJs which appear to be very short. This is probably caused by the poor trapping of quasiparticles. Detailed results on this process will be presented however at a later date.

  19. Spectroscopy of TaN in Support of Fundamental Physics

    Science.gov (United States)

    Mawhorter, Richard; Sharfi, David; Kim, Yongrak; Kokkin, Damian; Bouchard, Jacob; Steimle, Timothy

    2016-05-01

    Tantalum nitride, TaN, has been recently identified as a leading candidate for extending the study of T, P-odd effects in the nuclear realm to include proton, neutron, and quark electric dipole moments (EDM) and beyond. This is primarily due to enhancements in the interaction of electrons with the nuclear magnetic quadrupole moment (MQM) and the resulting parity-violating effects. Study of the dispersed laser induced fluorescence resulting from the excitation of the 17570.80 (Ω = 0+) , 18427.38 (Ω = 0+) , 19216.80 (Ω = 1), and 19396.78 (Ω = 1) bands above the X1Σ+ (v = 0) ground state of TaN near 569 nm, 543 nm, 520 nm, and 515 nm has enabled a determination of the branching ratios and transition dipole moments of all 4 states. Radiative lifetimes of 454(32) ns, 479(12) ns, 333(4) ns, and 480(17) ns respectively were measured from an analysis of the fluorescence decay curves, and potential optical pumping approaches for both populating and detecting the parity-violation sensitive 3Δ1 state are proposed. Further experiments using CW laser excitation have enabled the observation of the hyperfine structure of several bands in the gateway 18427.38 (Ω = 0+) to X1Σ+ (v = 0) transition, and analysis of these complex spectra is underway. DK, JB, and TS acknowledge support from NSF CHE-1265885, as do RM, DS, and YK from Pomona College.

  20. Design and Simulation of TF and TA Controller for Missile

    Institute of Scientific and Technical Information of China (English)

    ZHA Xu; GUANG Cheng-qi; CUI Ping-yuan; LIU Yong-cai

    2005-01-01

    A nonlinear terrain following(TF) and terrain avoidance(TA) controller is proposed for missile control systems.Based on classical TF algorithm (adaptive angle method), a new method for TF controller is proposed by using angle of attack. A method of obtaining terrain outline data from digital elevation map (DEM) for TF control is discussed in order to save store space. A TA algorithm is proposed by using bank-to-turn technique. The block control model, which is suitable for backstepping design, is given for nonlinear model of missile. Making full use of the characteristics of the system and combining block control principle and backstepping technique, a robust controller design method is proposed. Uncertainties in every sub-block are allowed, and can be canceled by using the idea of nonlinear damping. It is proved that the state tracking errors are converged to a neighborhood of the origin exponentially. Finally, nonlinear six-degree-of-freedom simulation results for the missile model are presented to demonstrate the effectiveness of the proposed control law.

  1. Reconnaissance of the Hydrogeology of Ta'u, American Samoa

    Science.gov (United States)

    Izuka, Scot K.

    2005-01-01

    Analysis of existing data and information collected on a reconnaissance field visit supports a conceptual model of ground-water occurrence in Ta'u, American Samoa, in which a thin freshwater lens exists in a predominantly high-permeability aquifer that receives high rates of recharge. Because the freshwater lens is thin throughout most of the island, the productivity of wells, especially those near the coast where the lens is the thinnest, is likely to be limited by saltwater intrusion. The landfill in northwestern Ta'u is closer to the north coast of the island than to any of the existing or proposed well sites. Although this may indicate that ground water beneath the landfill would flow away from the existing and proposed well sites, this interpretation may change depending on the hydraulic properties of a fault and rift zone in the area. Of four plausible scenarios tested with a numerical ground-water flow model, only one scenario indicated that ground water from beneath the landfill would flow toward the existing and proposed well sites; the analysis does not, however, assess which of the four scenarios is most plausible. The analysis also does not consider the change in flow paths that will result from ground-water withdrawals, dispersion of contaminants during transport by ground water, other plausible hydrogeologic scenarios, transport of contaminants by surface-water flow, or that sources of contamination other than the landfill may exist. Accuracy of the hydrologic interpretations in this study is limited by the relatively sparse data available for Ta'u. Understanding water resources on Ta'u can be advanced by monitoring rainfall, stream-flow, evaporation, ground-water withdrawals, and water quality, and with accurate surveys of measuring point elevations for all wells and careful testing of well-performance. Assessing the potential for contaminants in the landfill to reach existing and proposed well sites can be improved with additional information on the

  2. Effects of Ta Addition on NiTi Shape Memory Alloys

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    @@The effect of Ta addition on the martensitic transformation characteristics and the X-ray visibility on NiTi shape memory alloy have been studied in (Ni51Ti49)1-xTax system. It was found that the transformation temperatures of the Ni51Ti49 binary alloy increased drastically by an addition of 0~4 at. pct Ta, but only slightly when the concentration exceeded 4 at. pct; the addition of Ta greatly decreases the sensitivity of the martensitic transformations to the variation in the Ni-Ti ratio. The addition of Ta to the NiTi binary alloy can improve its X-ray visibility.

  3. Synthesis of Solar-Light-Responsive ZnO/TaON Nanocomposite and Their Photocatalytic Activity.

    Science.gov (United States)

    Kim, Tae-Ho; Jo, Yong-Hyun; Lee, Soo-Wohn; Cho, Sung-Hun; Kim, Seung-Ho

    2015-09-01

    The effects of the preparation conditions of ZnO-modified TaON on the photocatalytic activity for degradation of rhodamine B dye (Rh. B) under simulated solar light were investigated. The ZnO/TaON nanocomposite were prepared by loading particulate Ta2O5 with ZnO using different ZnO contents, followed by thermal nitridation at 1123 K for 5 h under NH3 flow (20 ml min(-1)). The as-prepared samples were characterized by XRD, UV-Vis-DRS, and SEM-EDX. The results revealed that the band gap energy absorption edge of as prepared nanocomposite samples was shifted to a longer wavelength as compared to ZnO and Ta2O5, and the 60 wt% ZnO/TaON nanocomposite exhibited the highest percentage (99.2%) of degradation of Rh. B and the highest reaction rate constant (0.0137 min(-1)) in 4 h which could be attributed to the enhanced absorption of the ZnO/TaON nanocomposite photocatalyst. Hence, these results suggest that the ZnO/TaON nanocomposite exhibits enhanced photocatalytic activity for the degradation of rhodamine B under simulated solar light irradiation in comparison to the commercial ZnO, Ta2O5, and TaON.

  4. Tandem Core-Shell Si-Ta3N5 Photoanodes for Photoelectrochemical Water Splitting.

    Science.gov (United States)

    Narkeviciute, Ieva; Chakthranont, Pongkarn; Mackus, Adriaan J M; Hahn, Christopher; Pinaud, Blaise A; Bent, Stacey F; Jaramillo, Thomas F

    2016-12-14

    Nanostructured core-shell Si-Ta3N5 photoanodes were designed and synthesized to overcome charge transport limitations of Ta3N5 for photoelectrochemical water splitting. The core-shell devices were fabricated by atomic layer deposition of amorphous Ta2O5 onto nanostructured Si and subsequent nitridation to crystalline Ta3N5. Nanostructuring with a thin shell of Ta3N5 results in a 10-fold improvement in photocurrent compared to a planar device of the same thickness. In examining thickness dependence of the Ta3N5 shell from 10 to 70 nm, superior photocurrent and absorbed-photon-to-current efficiencies are obtained from the thinner Ta3N5 shells, indicating minority carrier diffusion lengths on the order of tens of nanometers. The fabrication of a heterostructure based on a semiconducting, n-type Si core produced a tandem photoanode with a photocurrent onset shifted to lower potentials by 200 mV. CoTiOx and NiOx water oxidation cocatalysts were deposited onto the Si-Ta3N5 to yield active photoanodes that with NiOx retained 50-60% of their maximum photocurrent after 24 h chronoamperometry experiments and are thus among the most stable Ta3N5 photoanodes reported to date.

  5. Effects of helium and deuterium irradiation on SPS sintered W–Ta composites at different temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Mateus, R., E-mail: rmateus@ipfn.ist.utl.pt [Associação Euratom/IST, Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico, Universidade Técnica de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa (Portugal); Dias, M. [ITN, Instituto Tecnológico e Nuclear, Estrada Nacional 10, 2686-953 Sacavém (Portugal); Lopes, J. [ITN, Instituto Tecnológico e Nuclear, Estrada Nacional 10, 2686-953 Sacavém (Portugal); ISEL, Instituto Superior de Engenharia de Lisboa, Rua Conselheiro Emídio Navarro, 1, 1959-007 Lisboa (Portugal); Rocha, J.; Catarino, N.; Franco, N. [ITN, Instituto Tecnológico e Nuclear, Estrada Nacional 10, 2686-953 Sacavém (Portugal); Livramento, V. [Associação Euratom/IST, Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico, Universidade Técnica de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa (Portugal); LNEG, Laboratório Nacional de Energia e Geologia, Estrada do Paço do Lumiar, 1649-038 Lisboa (Portugal); and others

    2013-11-15

    Energetic He{sup +} and D{sup +} ions were implanted into different W–Ta composites in order to investigate their stability under helium and deuterium irradiation. The results were compared with morphological and chemical modifications arising from exposure of pure W and Ta. Special attention was given to tantalum hydride (Ta{sub 2}H) formation due to its implications for tritium inventory. Three W–Ta composites with 10 and 20 at.% Ta were prepared from elemental W powder and Ta fibre or powder through low-energy ball milling in argon atmosphere. Spark plasma sintering (SPS) was used as the consolidation process in the temperature range from 1473 to 1873 K. The results obtained from pure elemental samples and composites are similar. However, Ta{sub 2}H is easily formed in pure Ta by using a pre-implantation stage of He{sup +}, whereas in W–Ta composites the same reaction is clearly reduced, and it can be inhibited by controlling the sintering temperature.

  6. Overexpression of a Triticum aestivum Calreticulin gene (TaCRT1 Improves Salinity Tolerance in Tobacco.

    Directory of Open Access Journals (Sweden)

    Yang Xiang

    Full Text Available Calreticulin (CRT is a highly conserved and abundant multifunctional protein that is encoded by a small gene family and is often associated with abiotic/biotic stress responses in plants. However, the roles played by this protein in salt stress responses in wheat (Triticum aestivum remain obscure. In this study, three TaCRT genes were identified in wheat and named TaCRT1, TaCRT2 and TaCRT3-1 based on their sequence characteristics and their high homology to other known CRT genes. Quantitative real-time PCR expression data revealed that these three genes exhibit different expression patterns in different tissues and are strongly induced under salt stress in wheat. The calcium-binding properties of the purified recombinant TaCRT1 protein were determined using a PIPES/Arsenazo III analysis. TaCRT1 gene overexpression in Nicotiana tabacum decreased salt stress damage in transgenic tobacco plants. Physiological measurements indicated that transgenic tobacco plants showed higher activities of superoxide dismutase (SOD, peroxidase (POD and catalase (CAT than non-transgenic tobacco under normal growth conditions. Interestingly, overexpression of the entire TaCRT1 gene or of partial TaCRT1 segments resulted in significantly higher tolerance to salt stress in transgenic plants compared with their WT counterparts, thus revealing the essential role of the C-domain of TaCRT1 in countering salt stress in plants.

  7. Effects of annealing temperature on the magnetoresistance in Ta/NiFe/Ta films by ZnO intercalations

    Energy Technology Data Exchange (ETDEWEB)

    Ding, Lei, E-mail: Lding@hainu.edu.cn [Key Laboratory of Advanced Materials of Tropical Island Resources, Ministry of Education, Hainan University, Haikou 570228 (China); Yu, Guang-hua; Zhang, Min; Zhao, Chong-jun; Teng, Jiao [Department of Materials Physics and Chemistry, University of Science and Technology Beijing, Beijing 100083 (China); Xiang, Dao-ping [Key Laboratory of Advanced Materials of Tropical Island Resources, Ministry of Education, Hainan University, Haikou 570228 (China)

    2015-09-01

    Zinc oxide (ZnO) exhibiting many superior physical properties was inserted into the Ta/NiFe/Ta films as nano-oxide intercalations. Different annealing temperatures and ZnO thickness significantly affected the magnetoresistance (MR) in NiFe films. The 4-nm thick ZnO film annealed at 200 °C had a MR of 2.41%, which was more than 70% higher than that of the 1-nm thick ZnO annealed film (MR=1.40%). However, the further increase in annealing temperature to 300 °C rapidly deteriorated the MR performance of the films. Diffusion and interface reactions occur between the crystal ZnO and the adjacent NiFe layer. Lower-temperature annealing improved the interface, increasing the specular reflection of spin-polarized electrons to some extent. However, higher-temperature annealing induced severe diffusion and interface reactions, which led to a sharp decline in MR performance. - Highlights: • Combining NiFe with ZnO, thereby producing NiFe/ZnO interfaces. • Investigating the effects of annealing temperatures on the magnetoresistance. • Explaining the corresponding relationship between MR and microstructure.

  8. Interfacial electronic structure-modulated magnetic anisotropy in Ta/CoFeB/MgO/Ta multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Xi; Jiang, Shao Long; Yang, Guang; Liu, Yang; Teng, Jiao; Yu, Guang Hua, E-mail: ghyu@mater.ustb.edu.cn [Department of Materials Physics and Chemistry, University of Science and Technology Beijing, Beijing 100083 (China); Wang, Kai You [SKLSM, Institute of Semiconductors, CAS, P. O. Box 912, Beijing 100083 (China); Wu, Zheng Long [Analytical and Testing Center, Beijing Normal University, Beijing 100875 (China)

    2014-09-01

    We have observed several unexpected phenomena when a trace amount of Fe atoms is deposited onto the CoFeB/MgO interface in Ta/CoFeB/MgO/Ta multilayers. With the nominal thickness of the introduced Fe atoms (t{sub Fe}) varying from 0 to 0.1 Å, the effective magnetic anisotropy energy (K{sub eff}) of annealed multilayers is remarkably enhanced from 1.28 × 10{sup 6 }erg/cm{sup 3} to 2.14 × 10{sup 6 }erg/cm{sup 3}. As t{sub Fe} further increasing, the K{sub eff} decreases and even becomes negative when t{sub Fe} > 1 Å, indicating the change from perpendicular magnetic anisotropy to in-plane magnetic anisotropy. The analysis by X-ray photoelectron spectrometer reveals that the Fe atoms at annealed CoFeB/MgO interface show different electronic structures as t{sub Fe} increasing, which combine with O atoms to form FeO{sub x} (x < 1), Fe{sub 2}O{sub 3}, and Fe{sub 3}O{sub 4}, respectively, leading to modulation of Fe 3d-O 2p orbital hybridization and thus the K{sub eff}. On the other hand, we find that the introduction of Fe atoms also helps to reduce the multilayers' magnetic damping.

  9. Electrodeposited ultrafine TaOx/CB catalysts for PEFC cathode application: Their oxygen reduction reaction kinetics

    KAUST Repository

    Seo, Jeongsuk

    2014-12-01

    Ultrafine TaOx nanoparticles were electrodeposited on carbon black (CB) powder in a nonaqueous Ta complex solution at room temperature, and the resultant TaOx/CB catalysts were assessed as oxygen reduction reaction (ORR) electrocatalysts for polymer electrolyte fuel cell (PEFC) cathodes. The Ta electrodeposition process was scaled up using a newly designed working electrode containing a CB dense layer, without introducing any binder such as the ionomer Nafion in the electrode for electrodeposition. The electrodeposited TaOx/CB powders were removed from the deposition electrode and subsequent H2 treatment at varying temperatures between 523 and 1073 K was attempted to increase the ORR performance. The TaOx/CB samples were characterized by SEM, STEM, XPS, and EELS measurements. XPS and EELS results indicated the reduced nature of the Ta species caused by the high-temperature treatment in H2, while STEM images clearly revealed that the TaOx particles aggregated as the treatment temperature increased. When the TaOx/CB catalyst, which was treated at 873 K for 2 h, was deposited on a glassy carbon substrate with Nafion ionomer, it resulted in the highest activity among the samples investigated, giving an onset potential of 0.95 VRHE at -2 μA cm-2 in a 0.1 M H2SO4 solution. Moreover, the long-term stability test with 10,000 cycles of the voltammetry only led to a 6% loss in the ORR currents, demonstrating the high stability of the TaOx/CB catalysts. Kinetic analysis by R(R)DE indicated that the four-electron transfer pathway in the ORR process was dominant for this TaOx/CB catalyst, and Tafel plots showed a slope corresponding to a one-electron reaction for the rate-determining step.

  10. Electrochemical Corrosion Behavior of Ta2N Nanoceramic Coating in Simulated Body Fluid

    Directory of Open Access Journals (Sweden)

    Jian Cheng

    2016-09-01

    Full Text Available In order to improve the corrosion and wear resistance of biomedical Ti-6Al-4V implants, a Ta2N nanoceramic coating was synthesized on a Ti-6Al-4V substrate by the double glow discharge plasma process. The Ta2N coating, composed of fine nanocrystals, with an average grain size of 12.8 nm, improved the surface hardness of Ti-6Al-4V and showed good contact damage tolerance and good adhesion strength to the substrate. The corrosion resistance of the Ta2N coating in Ringer’s physiological solution at 37 °C was evaluated by different electrochemical techniques: potentiodynamic polarization, electrochemical impedance spectroscopy (EIS, potentiostatic polarization and capacitance measurements (Mott-Schottky approach. The evolution of the surface composition of the passive films at different applied potentials was determined by X-ray photoelectron spectroscopy (XPS. The results indicated that the Ta2N coating showed higher corrosion resistance than both commercially pure Ta and uncoated Ti-6Al-4V in this solution, because of the formed oxide film on the Ta2N coating having a smaller carrier density (Nd and diffusivity (Do of point defects. The composition of the surface passive film formed on the Ta2N coating changed with the applied potential. At low applied potentials, the oxidation of the Ta2N coating led to the formation of tantalum oxynitride (TaOxNy but, subsequently, the tantalum oxynitride (TaOxNy could be chemically converted to Ta2O5 at higher applied potentials.

  11. Enhancement of memory windows in Pt/Ta{sub 2}O{sub 5−x}/Ta bipolar resistive switches via a graphene oxide insertion layer

    Energy Technology Data Exchange (ETDEWEB)

    Chung, Je Bock; Bae, Yoon Cheol; Lee, Ah Rahm; Baek, Gwang Ho [Department of Nanoscale Semiconductor Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of); Lee, Min Yong [Department of Energy Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of); R& D Division, SK Hynix, Kyoungki-do 467-701 (Korea, Republic of); Yoon, Hee Wook; Park, Ho Bum [Department of Energy Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of); Hong, Jin Pyo, E-mail: jphong@hanyang.ac.kr [Department of Nanoscale Semiconductor Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of); The Research Institute for Natural Science, Novel Functional Materials and Devices Lab, Department of Physics, Hanyang University, Seoul 133-791 (Korea, Republic of)

    2015-07-31

    The influence of a graphene oxide (GO) layer on Pt/Ta{sub 2}O{sub 5−x}/Ta bipolar resistive switches, in which the GO layer is spin-coated on the Ta bottom electrode before the growth of a Ta{sub 2}O{sub 5−x} switching element was examined. Experimental observations suggest that the insertion of the GO layer is crucial for adjusting the low resistance states without changing the high resistance states. Controlling GO layer thickness represents the variation of the forming voltage and on/off ratio, demonstrating enhanced memory windows. The possible nature of the enhanced switching events is described by adapting the creation of strong conductive filaments driven by a greater resistive GO layer. - Highlights: • Graphene oxide (GO) layer functions as the strong conductive filaments. • The GO insertion layer controls the low resistance states of bipolar switching. • Memory windows of bipolar switching were intentionally manipulated.

  12. Effects of thickness and annealing condition on magnetic properties and thermal stabilities of Ta/Nd/NdFeB/Nd/Ta sandwiched films

    Science.gov (United States)

    Liu, Wen-Feng; Zhang, Min-Gang; Zhang, Ke-Wei; Zhang, Hai-Jie; Xu, Xiao-Hong; Chai, Yue-Sheng

    2016-11-01

    Ta/Nd/NdFeB/Nd/Ta sandwiched films are deposited by magnetron sputtering on Si (100) substrates, and subsequently annealed in vacuum at different temperatures for different time. It is found that both the thickness of NdFeB and Nd layer and the annealing condition can affect the magnetic properties of Ta/Nd/NdFeB/Nd/Ta films. Interestingly, the thickness and annealing temperature show the relevant behaviors that can affect the magnetic properties of the film. The high coercivity of 24.1 kOe (1 Oe = 79.5775 A/m) and remanence ratio (remanent magnetization/saturation magnetization) of 0.94 can be obtained in a Ta/Nd(250 nm)/NdFeB(600 nm)/Nd(250 nm)/Ta film annealed for 3 min at 1023 K. In addition, the thermal stability of the film is also linked to the thickness of NdFeB and Nd layer and the annealing temperature as well. The excellent thermal stability can be achieved in a Ta/Nd(250 nm)/NdFeB(600 nm)/Nd(250 nm)/Ta film annealed at 1023 K. Program supported by the National Natural Science Foundation of China (Grant No. 51305290), the Higher Education Technical Innovation Project of Shanxi Province, China (Grant No. 2013133), the Fund Program for the Scientific Activities of Selected Returned Overseas Professionals of Shanxi Province, China (Grant No. 2015003), and the Program for the Key Team of Scientific and Technological Innovation of Shanxi Province, China (Grant No. 2013131009).

  13. A New Kinetic Method of Processing TA Data

    Institute of Scientific and Technical Information of China (English)

    张建军; 任宁

    2004-01-01

    A new method of investigating the kinetic parameters and mechanism functions of a solid phase reaction is presented. This method is to analyze the data based on the use of these data at the same temperature and the same degree of conversion on a series of TA curves with different heating rates, so that the kinetic triplet-the activation energy E, the pre-exponential factor A and the analytical form of the function of conversion f(α) can be obtained.The main advantage of this method is that the values of E andf(α) are obtained respectively, and the determination off(α) is not under the influence of the value of E and the calculation of the value of E is not influenced by thef(α)either.

  14. La recerca lingüística en la TA

    OpenAIRE

    Melero i Nogués, Maite

    2006-01-01

    La recerca lingüística pot contribuir molt al desenvolupament de la Traducció Automàtica, i al problema fonamental de les divergències en la traducció, amb observacions de fenòmens, amb tècniques i teories que la recerca en TA pot adoptar i combinar amb mètodes estadístics d’anàlisi de corpus. La investigación lingüística puede contribuir mucho al desarrollo de la Traducción Automática, y al problema fundamental de las divergencias en la traducción, con observaciones de fenómenos, con técn...

  15. TaC Studios New Construction Test House

    Energy Technology Data Exchange (ETDEWEB)

    Butler, T.; Curtis, O.; Kim, E.; Roberts, S.; Stephenson, R.

    2013-03-01

    As part of the NAHB Research Center Industry Partnership, Southface partnered with TaC Studios, an Atlanta based architecture firm specializing in residential and light commercial design, on the construction of a new test home in Atlanta, GA in the mixed humid climate zone. This home will serve as a model home for the builder partner and addresses Building America energy savings targets through the planning and implementation of a design package will serve as a basis of design for the builder partner's future homes. As a BA test house, this home will be evaluated to detail whole house energy use, end use loads, and HVAC and hot water efficiency.

  16. Acoustic wave propagation in Ni3 ( = Mo, Nb, Ta) compounds

    Indian Academy of Sciences (India)

    Pramod Kumar Yadawa

    2011-04-01

    The ultrasonic properties of the hexagonal closed packed structured Ni3Mo, Ni3Nb and Ni3Ta compounds were studied at room temperature for their characterization. For the investigations of ultrasonic properties, the second-order elastic constants using Lennard–Jones potential were computed. The velocities 1 and 2 have minima and maxima respectively at 45° with the unique axis of the crystal, while 3 increases with respect to angle with the unique axis of the crystal. The inconsistent behaviour of angle-dependent velocities is associated with the action of second-order elastic constants. Debye average sound velocities of these compounds increase with the angle and has maximum at 55° with the unique axis at room temperature. Hence, when a sound wave travels at 55° with the unique axis of these materials, the average sound velocity is found to be maximum. The results achieved are discussed and compared with the available experimental and theoretical results.

  17. Electron Cloud at Low Emittance in CesrTA

    CERN Document Server

    Palmer, Mark; Billing, Michael; Calvey, Joseph; Conolly, Christopher; Crittenden, James; Dobbins, John; Dugan, Gerald; Eggert, Nicholas; Fontes, Ernest; Forster, Michael; Gallagher, Richard; Gray, Steven; Greenwald, Shlomo; Hartill, Donald; Hopkins, Walter; Kreinick, David; Kreis, Benjamin; Leong, Zhidong; Li, Yulin; Liu, Xianghong; Livezey, Jesse; Lyndaker, Aaron; Makita, Junki; McDonald, Michael; Medjidzade, Valeri; Meller, Robert; O'Connell, Tim; Peck, Stuart; Peterson, Daniel; Ramirez, Gabriel; Rendina, Matthew; Revesz, Peter; Rider, Nate; Rice, David; Rubin, David; Sagan, David; Savino, James; Schwartz, Robert; Seeley, Robert; Sexton, James; Shanks, James; Sikora, John; Smith, Eric; Strohman, Charles; Williams, Heather; Antoniou, Fanouria; Calatroni, Sergio; Gasior, Marek; Jones, Owain Rhodri; Papaphilippou, Yannis; Pfingstner, Juergen; Rumolo, Giovanni; Schmickler, Hermann; Taborelli, Mauro; Asner, David; Boon, Laura; Garfinkel, Arthur; Byrd, John; Celata, Christine; Corlett, John; De Santis, Stefano; Furman, Miguel; Jackson, Alan; Kraft, Rick; Munson, Dawn; Penn, Gregory; Plate, David; Venturini, Marco; Carlson, Benjamin; Demma, Theo; Dowd, Rohan; Flanagan, John; Jain, Puneet; Kanazawa, Ken-ichi; Kubo, Kiyoshi; Ohmi, Kazuhito; Sakai, Hiroshi; Shibata, Kyo; Suetsugu, Yusuke; Tobiyama, Makoto; Gonnella, Daniel; Guo, Weiming; Harkay, Katherine; Holtzapple, Robert; Jones, James; Wolski, Andrzej; Kharakh, David; Ng, Johnny; Pivi, Mauro; Wang, Lanfa; Ross, Marc; Tan, Cheng-Yang; Zwaska, Robert; Schachter, Levi; Wilkinson, Eric

    2010-01-01

    The Cornell Electron Storage Ring (CESR) has been reconfigured as a test accelerator (CesrTA) for a program of electron cloud (EC) research at ultra low emittance. The instrumentation in the ring has been upgraded with local diagnostics for measurement of cloud density and with improved beam diagnostics for the characterization of both the low emittance performance and the beam dynamics of high intensity bunch trains interacting with the cloud. A range of EC mitigation methods have been deployed and tested and their effectiveness is discussed. Measurements of the electron cloud’s effect on the beam under a range of conditions are discussed along with the simulations being used to quantitatively understand these results

  18. MICROSTRUCTURAL STABILITY OF Ti-46Al-8Ta DURING CREEP

    Directory of Open Access Journals (Sweden)

    Hana Staneková

    2011-05-01

    Full Text Available The effect of long-term creep exposure on the microstructure stability of a new cast air-hardenable intermetallic alloy with nominal chemical composition Ti-46Al-8Ta (at .% was studied. Constat load creep test were performed at the temperature 750°C and at applied stress 250 MPa up to 3479,3 h. The initial gama(TiAl + alpha2(Ti3Al microstructure of the alloy is unstable and transforms to alpha2 + gama + tau type. During creep the formation of cavities along the lamellar colony and grain boundaries is observed. The specimens fail by the growth and coalescence of such cavities with intergranular type of fracture.

  19. Electron Cloud at Low Emittance in CesrTA

    Energy Technology Data Exchange (ETDEWEB)

    Palmer, Mark; /Cornell U., CLASSE; Alexander, James; /Cornell U., CLASSE; Billing, Michael; /Cornell U., CLASSE; Calvey, Joseph; /Cornell U., CLASSE; Conolly, Christopher; /Cornell U., CLASSE; Crittenden, James; /Cornell U., CLASSE; Dobbins, John; /Cornell U., CLASSE; Dugan, Gerald; /Cornell U., CLASSE; Eggert, Nicholas; /Cornell U., CLASSE; Fontes, Ernest; /Cornell U., CLASSE; Forster, Michael; /Cornell U., CLASSE; Gallagher, Richard; /Cornell U., CLASSE; Gray, Steven; /Cornell U., CLASSE; Greenwald, Shlomo; /Cornell U., CLASSE; Hartill, Donald; /Cornell U., CLASSE; Hopkins, Walter; /Cornell U., CLASSE; Kreinick, David; /Cornell U., CLASSE; Kreis, Benjamin; /Cornell U., CLASSE; Leong, Zhidong; /Cornell U., CLASSE; Li, Yulin; /Cornell U., CLASSE; Liu, Xianghong; /Cornell U., CLASSE /Cornell U., CLASSE /Cornell U., CLASSE /Cornell U., CLASSE /Cornell U., CLASSE /Cornell U., CLASSE /Cornell U., CLASSE /Cornell U., CLASSE /Cornell U., CLASSE /Cornell U., CLASSE /Cornell U., CLASSE /Cornell U., CLASSE /Cornell U., CLASSE /Cornell U., CLASSE /Cornell U., CLASSE /Cornell U., CLASSE /Cornell U., CLASSE /Cornell U., CLASSE /Cornell U., CLASSE /Cornell U., CLASSE /Cornell U., CLASSE /Cornell U., CLASSE /Cornell U., CLASSE /Cornell U., CLASSE /Cornell U., CLASSE /Cornell U., CLASSE /CERN /CERN /CERN /CERN /CERN /CERN; /more authors..

    2012-07-06

    The Cornell Electron Storage Ring (CESR) has been reconfigured as a test accelerator (CesrTA) for a program of electron cloud (EC) research at ultra low emittance. The instrumentation in the ring has been upgraded with local diagnostics for measurement of cloud density and with improved beam diagnostics for the characterization of both the low emittance performance and the beam dynamics of high intensity bunch trains interacting with the cloud. A range of EC mitigation methods have been deployed and tested and their effectiveness is discussed. Measurements of the electron cloud's effect on the beam under a range of conditions are discussed along with the simulations being used to quantitatively understand these results.

  20. Electron Cloud at Low Emittance in CesrTA

    Energy Technology Data Exchange (ETDEWEB)

    Alexander, J. P.; Billing, M. G.; Calvey, J.; Crittenden, J. A.; Dugan, G.; Eggert, N.; Forster, M.; Greenwald, S.; Hartill, D. L.; Hopkins, W. H.; Kreinick, D. L.; Li, Y.; Liu, X.; Livezey, J. A.; Meller, R.; Peck, S.; Peterson, D. P.; Rice, D.; Rider, N.; Rubin, D.; Sagan, D.; Schwartz, R.; Shanks, J. P.; Sikora, J.; Harkay, K. C.; Antoniou, F.; Calatroni, S.; Gasior, M.; Papaphilippou, Y.; Pfingstner, J.; Rumolo, G.; Schmickler, H.; Taborelli, M.; Holtzapple, R.; Jones, J.; Wolski, A.; Tan, C.Y.; Zwaska, R. M; Flanagan, J. W.; Kanazawa, K.I.; Sakai, H.; Shibata, K.; Suetsugu, Y.; Byrd, J.; Corlett, J.; De Santis, S.; Furman, M.; Kraft, R.; Munson, D. V.; Penn, G.; Plate, D.; Venturini, M.; Pivi, M. T. F.; Wang, L.; Schachter, L.

    2010-05-23

    The Cornell Electron Storage Ring (CESR) has been reconfigured as a test accelerator (CesrTA) for a program of electron cloud (EC) research at ultra low emittance. The instrumentation in the ring has been upgraded with local diagnostics for measurement of cloud density and with improved beam diagnostics for the characterization of both the low emittance performance and the beam dynamics of high intensity bunch trains interacting with the cloud. A range of EC mitigation methods have been deployed and tested and their effectiveness is discussed. Measurements of the electron cloud's effect on the beam under a range of conditions are discussed along with the simulations being used to quantitatively understand these results.

  1. Atomistic simulation of shocks in single crystal and polycrystalline Ta

    Science.gov (United States)

    Bringa, E. M.; Higginbotham, A.; Park, N.; Tang, Y.; Suggit, M.; Mogni, G.; Ruestes, C. J.; Hawreliak, J.; Erhart, P.; Meyers, M. A.; Wark, J. S.

    2011-06-01

    Non-equilibrium molecular dynamics (MD) simulations of shocks in Ta single crystals and polycrystals were carried out using up to 360 million atoms. Several EAM and FS type potentials were tested up to 150 GPa, with varying success reproducing the Hugoniot and the behavior of elastic constants under pressure. Phonon modes were studied to exclude possible plasticity nucleation by soft-phonon modes, as observed in MD simulations of Cu crystals. The effect of loading rise time in the resulting microstructure was studied for ramps up to 0.2 ns long. Dislocation activity was not observed in single crystals, unless there were defects acting as dislocation sources above a certain pressure. E.M.B. was funded by CONICET, Agencia Nacional de Ciencia y Tecnología (PICT2008-1325), and a Royal Society International Joint Project award.

  2. Charge fluctuations and nodeless superconductivity in quasi-one-dimensional Ta4Pd3Te16 revealed by 125Te-NMR and 181Ta-NQR

    Science.gov (United States)

    Li, Z.; Jiao, W. H.; Cao, G. H.; Zheng, Guo-qing

    2016-11-01

    We report 125Te nuclear magnetic resonance and 181Ta nuclear quadrupole resonance studies on single-crystal Ta4Pd3Te16 , which has a quasi-one-dimensional structure and superconducts below Tc=4.3 K. 181Ta with spin I =7 /2 is sensitive to quadrupole interactions, while 125Te with spin I =1 /2 can only relax by magnetic interactions. By comparing the spin-lattice relaxation rate (1 /T1 ) of 181Ta and 125Te, we found that electric-field-gradient (EFG) fluctuations develop below 80 K. The EFG fluctuations are enhanced with decreasing temperature due to the fluctuations of a charge density wave that sets in at TCDW=20 K, below which the spectra are broadened and 1 /T1T drops sharply. In the superconducting state, 1 /T1 shows a Hebel-Slichter coherence peak just below Tc for 125Te, indicating that Ta4Pd3Te16 is a full-gap superconductor without nodes in the gap function. The coherence peak is absent in the 1 /T1 of 181Ta due to the strong EFG fluctuations.

  3. Using the TA to Prepare Graduate Students for Research and Employment

    Science.gov (United States)

    Heller, Kenneth

    One of the most underused components of the physics graduate program is the time spent being a teaching assistant (TA). Often the TA duties consist of grading and trying to help undergraduates survive a physics course. How those duties are accomplished is left to each TA. The most common TA preparation, if it exists, has a narrow focus on the class being taught. Preparation consists of describing, or perhaps practicing, specific teaching skills and gaining familiarity with the equipment used in the laboratory portion of the class. Instead TAs can be integrated into the entire course in which they function so that they learn the course as a system. This means treating a course in the same way one approaches a research project with the TAs as members of the research team headed by a faculty advisor. TA preparation is broadened and support includes the management, teamwork, and communication skills necessary. This makes the TAs more efficient and effective teachers while explicitly connecting the TA experience to the ``soft'' skills they need in their own research careers whether in industry, national laboratories, or academia. This talk describes such a program, functioning for over 20 years at the University of Minnesota, that takes no more time than the usual TA but results in graduate students that are more satisfied with their TA experience, are better prepared to function in research groups, and provide a better classroom experience for their undergraduate students.

  4. Nanocrystalline β-Ta Coating Enhances the Longevity and Bioactivity of Medical Titanium Alloys

    Directory of Open Access Journals (Sweden)

    Linlin Liu

    2016-09-01

    Full Text Available A β-Ta nanocrystalline coating was engineered onto a Ti-6Al-4V substrate using a double cathode glow discharge technique to improve the corrosion resistance and bioactivity of this biomedical alloy. The new coating has a thickness of ~40 μm and exhibits a compact and homogeneous structure composed of equiaxed β-Ta grains with an average grain size of ~22 nm, which is well adhered on the substrate. Nanoindentation and scratch tests indicated that the β-Ta coating exhibited high hardness combined with good resistance to contact damage. The electrochemical behavior of the new coating was systematically investigated in Hank’s physiological solution at 37 °C. The results showed that the β-Ta coating exhibited a superior corrosion resistance as compared to uncoated Ti-6Al-4V and commercially pure tantalum, which was attributed to a stable passive film formed on the β-Ta coating. The in vitro bioactivity was studied by evaluating the apatite-forming capability of the coating after seven days of immersion in Hank’s physiological solution. The β-Ta coating showed a higher apatite-forming ability than both uncoated Ti-6Al-4V and commercially pure Ta, suggesting that the β-Ta coating has the potential to enhance functionality and increase longevity of orthopaedic implants.

  5. "Forest Grove School District v. T.A." Supreme Court Case: Implications for School Psychology Practice

    Science.gov (United States)

    Dixon, Shauna G.; Eusebio, Eleazar C.; Turton, William J.; Wright, Peter W. D.; Hale, James B.

    2011-01-01

    The 2009 "Forest Grove School District v. T.A." United States Supreme Court case could have significant implications for school psychology practice. The Court ruled that the parents of a student with a disability were entitled to private school tuition reimbursement even though T.A. had not been identified with a disability or previously…

  6. Fabrication of ultrathin films of Ta2O5 by a sol-gel method

    NARCIS (Netherlands)

    Wolf, M.J.; Roitsch, J.; Mayer, J.; Nijmeijer, A.; Bouwmeester, H.J.M.

    2013-01-01

    Tantalum oxide (Ta2O5) is widely known for its high chemical, thermal and hydrothermal stability. In this study, a sol–gel method has been developed to produce homogenous, i.e., defect and pin-hole free, ultrathin films of Ta2O5. These were coated onto a porous substrate by means of dip-coating, and

  7. Resonant optical absorption and defect control in Ta3N5 photoanodes

    NARCIS (Netherlands)

    Dabirian, A.; Van de Krol, R.

    2013-01-01

    In this study, we explore resonance-enhanced optical absorption in Ta3N5 photoanodes for water splitting. By using a reflecting Pt back-contact and appropriate Ta3N5 film thickness, the resonance frequency can be tuned to energies just above the bandgap, where the optical absorption is normally weak

  8. "Forest Grove School District v. T.A." Supreme Court Case: Implications for School Psychology Practice

    Science.gov (United States)

    Dixon, Shauna G.; Eusebio, Eleazar C.; Turton, William J.; Wright, Peter W. D.; Hale, James B.

    2011-01-01

    The 2009 "Forest Grove School District v. T.A." United States Supreme Court case could have significant implications for school psychology practice. The Court ruled that the parents of a student with a disability were entitled to private school tuition reimbursement even though T.A. had not been identified with a disability or previously provided…

  9. Evaluation of the CoCrTaPt alloy for longitudinal magnetic recording

    Science.gov (United States)

    Cheng, Yuanda; Sedighi, Mojtaba; Lam, Irene; Gardner, Richard A.; Yang, ZhiJun; Scheinfein, Michael R.

    1994-05-01

    A quaternary alloy of CoCrTaPt with a composition of 80-10-4-6 (in at. %) was evaluated for its magnetic and recording properties. Samples of C/CoCrTaPt/Cr recording media were prepared by dc magnetron sputtering on circumferentially textured Al/NiP substrates. The effects on static magnetic properties and recording performance were studied for different substrate preheating times, Cr underlayer thicknesses, and Co-alloy layer thicknesses. It was found that both the coercivity Hc and remanent magnetization Mr increased with substrate preheating time. Hc also increased with Cr underlayer thickness, as expected. The Mrδ value depended linearly on the Co-alloy layer thickness. In addition, we found that the coercivity increased dramatically as the magnetic layer thickness decreased from ˜800 to ˜200 Å. For a sample with a 235-Å CoCrTaPt magnetic layer and ˜1000-Å Cr underlayer, the coercivity was found to be ≳2700 Oe. Parametric evaluation showed that CoCrTaPt samples have performance similar to samples of CoCrTa and, because of the Pt addition, the CoCrTaPt alloy offers significantly higher attainable coercivities than the CoCrTa alloy. Therefore, the CoCrTaPt alloy proves to be a good candidate for use in high density recording media which require coercivity of higher than 2000 Oe.

  10. Atomistic simulation of Cu-Ta thin film deposition and other phenomena

    NARCIS (Netherlands)

    Klaver, T.P.C.

    2004-01-01

    Tantalum (Ta) is a metal with good properties to act as a diffusion barrier material in computer chips, where it should prevent the mixing of Cu into Si and SiO. The deposition of thin Cu films onto various Ta substrates has been studied through molecular dynamics simulations, using either empirical

  11. A View from the Cocoon--Space Categorization in the Korean Verb [na-ka-ta].

    Science.gov (United States)

    Kim, Alan Hyun-Oak

    1996-01-01

    Analysis of the Korean verb "na-ka-ta" ("to get out, exit") focuses on why an expression such as "kyengkicang-ey na-ka-ta" ("someone goes out/in to the sports arena") is acceptable only in the context that the person's entering the arena is for the purpose of a contest, while it becomes semantically…

  12. Planar interdigitated electrolyte-conductivity sensors on an insulating substrate covered with Ta2O5

    NARCIS (Netherlands)

    Olthuis, W.; Sprenkels, A.J.; Bomer, J.G.; Bergveld, P.

    1997-01-01

    Interdigitated electrolyte-conductivity sensors with an added top layer of insulating Ta2O5 have been realized. The electrode-substrate structure under the Ta2O5 film has been planarized in order to obtain a totally flat top surface. In addition, the electrodes have been applied on a totally insulat

  13. Overexpression of the wheat aquaporin gene, TaAQP7, enhances drought tolerance in transgenic tobacco.

    Directory of Open Access Journals (Sweden)

    Shiyi Zhou

    Full Text Available Aquaporin (AQP proteins have been shown to transport water and other small molecules through biological membranes, which is crucial for plants to combat stress caused by drought. However, the precise role of AQPs in drought stress response is not completely understood in plants. In this study, a PIP2 subgroup gene AQP, designated as TaAQP7, was cloned and characterized from wheat. Expression of TaAQP7-GFP fusion protein revealed its localization in the plasma membrane. TaAQP7 exhibited high water channel activity in Xenopus laevis oocytes and TaAQP7 transcript was induced by dehydration, and treatments with polyethylene glycol (PEG, abscisic acid (ABA and H(2O(2. Further, TaAQP7 was upregulated after PEG treatment and was blocked by inhibitors of ABA biosynthesis, implying that ABA signaling was involved in the upregulation of TaAQP7 after PEG treatment. Overexpression of TaAQP7 increased drought tolerance in tobacco. The transgenic tobacco lines had lower levels of malondialdehyde (MDA and H(2O(2, and less ion leakage (IL, but higher relative water content (RWC and superoxide dismutase (SOD and catalase (CAT activities when compared with the wild type (WT under drought stress. Taken together, our results show that TaAQP7 confers drought stress tolerance in transgenic tobacco by increasing the ability to retain water, reduce ROS accumulation and membrane damage, and enhance the activities of antioxidants.

  14. TA 55 Reinvestment Project II Phase C Update Project Status May 23, 2017

    Energy Technology Data Exchange (ETDEWEB)

    Giordano, Anthony P. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-05-25

    The TA-55 Reinvestment Project (TRP) II Phase C is a critical infrastructure project focused on improving safety and reliability of the Los Alamos National Laboratory (LANL) TA-55 Complex. The Project recapitalizes and revitalizes aging and obsolete facility and safety systems providing a sustainable nuclear facility for National Security Missions.

  15. Methane Activation by Tantalum Carbide Cluster Anions Ta2C4().

    Science.gov (United States)

    Li, Hai-Fang; Zhao, Yan-Xia; Yuan, Zhen; Liu, Qing-Yu; Li, Zi-Yu; Li, Xiao-Na; Ning, Chuan-Gang; He, Sheng-Gui

    2017-02-02

    Methane activation by transition metals is of fundamental interest and practical importance, as this process is extensively involved in the natural gas conversion to fuels and value-added chemicals. While single-metal centers have been well recognized as active sites for methane activation, the active center composed of two or more metal atoms is rarely addressed and the detailed reaction mechanism remains unclear. Here, by using state-of-the-art time-of-flight mass spectrometry, cryogenic anion photoelectron imaging spectroscopy, and quantum-chemical calculations, the cooperation of the two Ta atoms in a dinuclear carbide cluster Ta2C4(-) for methane activation has been identified. The C-H bond activation takes place predominantly around one Ta atom in the initial stage of the reaction and the second Ta atom accepts the delivered H atom from the C-H bond cleavage. The well-resolved vibrational spectra of the cryogenically cooled anions agree well with theoretical simulations, allowing the clear characterization of the structure of Ta2C4(-) cluster. The reactivity comparison between Ta2C4(-) cluster and the carbon-less analogues (Ta2C3(-) and Ta2C2(-)) demonstrated that the cooperative effect of the two metal atoms can be well tuned by the carbon ligands in terms of methane activation and transformation.

  16. Synthesis, crystal structure, and photocatalytical properties of Ba3Ta5O14N

    Science.gov (United States)

    Anke, B.; Bredow, T.; Soldat, J.; Wark, M.; Lerch, M.

    2016-01-01

    Light yellow Ba3TaV5O14N was successfully synthesized as phase-pure material crystallizing isostructurally to well-known mixed-valence Ba3TaV4TaIVO15. The electronic structure of Ba3Ta5O14N was studied theoretically with a hybrid Hartree-Fock-DFT method. The most stable structure was obtained when nitrogen atoms were placed at 4 h sites having fourfold coordination. By incorporating nitrogen, the band gap decreases from ∼3.8 eV commonly known for barium tantalum(V) oxides to 2.8 eV for the oxide nitride, giving rise to an absorption band well in the visible-light region. Ba3Ta5O14N was also tested for photocatalytic hydrogen formation.

  17. Preparation and photocatalytic performance of iodine-doped NaTaO3 nanoparticles.

    Science.gov (United States)

    Han, Peilin; Su, Yiguo; Meng, Yue; Wang, Shuwei; Jia, Qingyue; Wang, Xiaojing

    2011-11-01

    Iodine-doped NaTaO3 nanoparticles were prepared by hydrothermal conditions and explored as the visible-light-driven photocatalysts for photodegradation of methylene blue in water. It is found that I-doped NaTaO3 showed photodegradation efficiency superior over the un-doped NaTaO3. UV-Vis diffuse reflectance spectra indicate that the absorption edges shifted towards longer wavelength with increasing the iodine concentration. The energy band structure and the transient behavior of the photogenerated charge carriers for both un-doped and doped NaTaO3 powders were investigated using density functional theory. The improved photocatalytic activity under visible light for I-doped NaTaO3 may be caused by both the broadening of valence band that inhibited the recombination of e-h+ pairs and the narrowing of energy band gap due to the much negative energy levels in the bottom of conduction bands.

  18. Thermodynamic and mechanical stabilities of tantalum nitride Ta2N3

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Chao [Los Alamos National Laboratory; Lin, Zhijun [Los Alamos National Laboratory; Zhao, Yusheng [Los Alamos National Laboratory

    2009-01-01

    We perform first-principles density functional calculations on a newly discovered tantalum nitride with an orthorhombic U{sub 2}S{sub 3} structure to assess its thermodynamic and mechanical stabilities. Our random search unveils a tetragonal Ta{sub 2}N{sub 3} structure that is energetically more favorable than an orthorhombic Ta{sub 2}N{sub 3} at zero pressure. We predict that the tetragonal Ta{sub 2}N{sub 3} transforms into the orthorhombic phase above a relatively low pressure of 7.7 GPa. Single-crystal elastic constant calculations reveal that orthorhombic Ta{sub 2}N{sub 3} is mechanically unstable because of a negative c{sub 66}. Our calculations suggest that minor oxygen substitution for nitrogen plays an important role in stabilizing the orthorhombic Ta{sub 2}N{sub 3} structure.

  19. Washing powders and the environment: has TAED any influence on the complexing behaviour of phosphonic acids?

    Science.gov (United States)

    Deluchat, Véronique; Lacour, Stella; Serpaud, Bernard; Bollinger, Jean-Claude

    2002-10-01

    Complexation properties of two phosphonic acids: nitrilotris (methylenephosphonic acid) and 1-hydroxyethane-1,1'-diphosphonic acid, with Cu(II) and Ca(II) have been previously determined by pH and ionic selective electrode titrations. These phosphonic acids are commonly added to washing powders as polyphosphate substitutes and are here studied in the presence of another detergent compound: tetraacetylethylenediamine (TAED), a bleaching activator. Product concentrations were chosen in order to correspond to component concentration ratios encountered in washing powders. Potentiometric titrations were carried out to determine the possible TAED interferences; they indicate that TAED and its by-products have no action on phosphonic acid complexing behaviour. Under our experimental conditions, the action of TAED was modelled with acetic acid and ethylenediamine, the final by-products of TAED hydrolysis. If we take into account both phosphonic and acetic acids, speciation diagrams corresponding to representative fresh water systems showed that the acetic acid does not influence cation speciation.

  20. Atomic resolution investigations of phase transformation from TaN to CrTaN in a steel matrix

    DEFF Research Database (Denmark)

    Danielsen, Hilmar Kjartansson; Hald, John

    2012-01-01

    , thus preserving long-term creep strength. This can be done by alloying with Ta instead of Nb and V. Recent investigations have indicated a direct transformation of MN into CrMN to take place, not the traditional nucleation/dissolution process. In this paper atomic resolution microscopy shows how Cr......In development of 12%Cr high temperature steels used for fossil fired power plants, the precipitation of large Z-phase particles, CrMN, has been identified as a major problem since they replace small and finely distributed MN particles. This causes a premature breakdown in the longterm creep...... strength of the steel. The Cr content promotes Z-phase precipitation, making MN strengthening of these materials unfeasible, since 12%Cr is necessary for oxidation resistance. The authors have suggested an acceleration of Z-phase precipitation to obtain a fine and stable distribution of CrMN instead of MN...

  1. Assessment of Radiometer Calibration with GPS Radio Occultation for the MiRaTA CubeSat Mission.

    Science.gov (United States)

    Marinan, Anne D; Cahoy, Kerri L; Bishop, Rebecca L; Lui, Susan S; Bardeen, James R; Mulligan, Tamitha; Blackwell, William J; Leslie, R Vincent; Osaretin, Idahosa; Shields, Michael

    2016-12-01

    The Microwave Radiometer Technology Acceleration (MiRaTA) is a 3U CubeSat mission sponsored by the NASA Earth Science Technology Office (ESTO). The science payload on MiRaTA consists of a tri-band microwave radiometer and Global Positioning System (GPS) radio occultation (GPSRO) sensor. The microwave radiometer takes measurements of all-weather temperature (V-band, 50-57 GHz), water vapor (G-band, 175-191 GHz), and cloud ice (G-band, 205 GHz) to provide observations used to improve weather forecasting. The Aerospace Corporation's GPSRO experiment, called the Compact TEC (Total Electron Content) and Atmospheric GPS Sensor (CTAGS), measures profiles of temperature and pressure in the upper troposphere/lower stratosphere (∼20 km) and electron density in the ionosphere (over 100 km). The MiRaTA mission will validate new technologies in both passive microwave radiometry and GPS radio occultation: (1) new ultra-compact and low-power technology for multi-channel and multi-band passive microwave radiometers, (2) the application of a commercial off the shelf (COTS) GPS receiver and custom patch antenna array technology to obtain neutral atmospheric GPSRO retrieval from a nanosatellite, and (3) a new approach to spaceborne microwave radiometer calibration using adjacent GPSRO measurements. In this paper, we focus on objective (3), developing operational models to meet a mission goal of 100 concurrent radiometer and GPSRO measurements, and estimating the temperature measurement precision for the CTAGS instrument based on thermal noise. Based on an analysis of thermal noise of the CTAGS instrument, the expected temperature retrieval precision is between 0.17 K and 1.4 K, which supports the improvement of radiometric calibration to 0.25 K.

  2. Virus-Induced Gene Silencing Identifies an Important Role of the TaRSR1 Transcription Factor in Starch Synthesis in Bread Wheat

    Directory of Open Access Journals (Sweden)

    Guoyu Liu

    2016-09-01

    Full Text Available The function of a wheat starch regulator 1 (TaRSR1 in regulating the synthesis of grain storage starch was determined using the barley stripe mosaic virus—virus induced gene-silencing (BSMV-VIGS method in field experiments. Chlorotic stripes appeared on the wheat spikes infected with barley stripe mosaic virus-virus induced gene-silencing- wheat starch regulator 1 (BSMV-VIGS-TaRSR1 at 15 days after anthesis, at which time the transcription levels of the TaRSR1 gene significantly decreased. Quantitative real-time PCR was also used to measure the transcription levels of 26 starch synthesis-related enzyme genes in the grains of BSMV-VIGS-TaRSR1-silenced wheat plants at 20, 27, and 31 days after anthesis. The results showed that the transcription levels of some starch synthesis-related enzyme genes were markedly induced at different sampling time points: TaSSI, TaSSIV, TaBEIII, TaISA1, TaISA3, TaPHOL, and TaDPE1 genes were induced at each of the three sampling time points and TaAGPS1-b, TaAGPL1, TaAGPL2, TaSSIIb, TaSSIIc, TaSSIIIb, TaBEI, TaBEIIa, TaBEIIb, TaISA2, TaPHOH, and TaDPE2 genes were induced at one sampling time point. Moreover, both the grain starch contents, one thousand kernel weights, grain length and width of BSMV-VIGS-TaRSR1-infected wheat plants significantly increased. These results suggest that TaRSR1 acts as a negative regulator and plays an important role in starch synthesis in wheat grains by temporally regulating the expression of specific starch synthesis-related enzyme genes.

  3. The Antibacterial Activity of Ta-doped ZnO Nanoparticles.

    Science.gov (United States)

    Guo, Bing-Lei; Han, Ping; Guo, Li-Chuan; Cao, Yan-Qiang; Li, Ai-Dong; Kong, Ji-Zhou; Zhai, Hai-Fa; Wu, Di

    2015-12-01

    A novel photocatalyst of Ta-doped ZnO nanoparticles was prepared by a modified Pechini-type method. The antimicrobial study of Ta-doped ZnO nanoparticles on several bacteria of Gram-positive Bacillus subtilis (B. subtilis) and Staphylococcus aureus (S. aureus) and Gram-negative Escherichia coli (E. coli) and Pseudomonas aeruginosa (P. aeruginosa) were performed using a standard microbial method. The Ta-doping concentration effect on the minimum inhibitory concentration (MIC) of various bacteria under dark ambient has been evaluated. The photocatalytical inactivation of Ta-doped ZnO nanoparticles under visible light irradiation was examined. The MIC results indicate that the incorporation of Ta(5+) ions into ZnO significantly improve the bacteriostasis effect of ZnO nanoparticles on E. coli, S. aureus, and B. subtilis in the absence of light. Compared to MIC results without light irradiation, Ta-doped ZnO and pure ZnO nanoparticles show much stronger bactericidal efficacy on P. aeruginosa, E. coli, and S. aureus under visible light illumination. The possible antimicrobial mechanisms in Ta-doped ZnO systems under visible light and dark conditions were also proposed. Ta-doped ZnO nanoparticles exhibit more effective bactericidal efficacy than pure ZnO in dark ambient, which can be attributed to the synergistic effect of enhanced surface bioactivity and increased electrostatic force due to the incorporation of Ta(5+) ions into ZnO. Based on the antibacterial tests, 5 % Ta-doped ZnO is a more effective antimicrobial agent than pure ZnO.

  4. 75 FR 66794 - Notice of Affirmative Determination Regarding Application for Reconsideration: TA-W-71,572...

    Science.gov (United States)

    2010-10-29

    ...., Steubenville, OH By applications dated May 15 and May 21, 2010, United Steel, Paper and Forestry, Rubber... back plate coils (TA-W-71,572A), hot rolled coils (TA- W-71,572B), and cold rolled coils...

  5. Landslide risk assessment in the Göta Älv river valley to limit consequences of climate change on society

    Science.gov (United States)

    Hedlund, Jonas; Lind, Bo; Tremblay, Marius; Zackrisson, Peter; Cederbom, Charlotte

    2010-05-01

    Higher temperatures, higher average precipitation and increased occurrence of extreme rainfall events are some expected climate changes in Sweden during the coming 70-100 years. Due to the changing climate the risk for floods, erosion and landslides are expected to increase. in large parts of the country. To prevent extensive floodings and damages of cities and infrastructure around Lake Vänern, it is necessary to allow controlled overflow from Lake Vänern through the river Göta Älv. An overflow in the river, in turn, leads to increased risk for erosion and landslides along the Göta Älv valley. In order to meet the upcoming climate changes and to handle the increasing flows through the river, we need to improve the knowledge of the stability of the entire river bank. The Swedish Government has commissioned the Swedish Geotechnical Institute (SGI) to investigate the landslide potential of the Göta Älv valley, taking the predicted climate changes into consideration. The investigated area includes the parts of Göta Älv that could be affected by the increased flows from Lake Vänern; areas where the increased flow will affect stability and where landslides could cause serious damages or damming of the river. The investigation area includes c. 90 km of the Göta Älv river plus tributaries in connection to Göta Älv. In the landslide risk analyses developed for Göta Älv, the likelihood of landslides and estimation of the subsequent consequences are included. The methodology involves mapping of landslide hazards and a judgement of the risk area on the basis of a risk matrix. The landslide risk analysis allows for an assessment of where geotechnical reinforcements would be necessary. A cost estimation for the required reinforcement measures is also provided. In areas where the estimated risk for a landslide is low (e.g. limited consequences), stability mapping in accordance with the model used by the Swedish Civil Contingencies Agency (MSB) is developed

  6. Estimating Daily Maximum and Minimum Land Air Surface Temperature Using MODIS Land Surface Temperature Data and Ground Truth Data in Northern Vietnam

    Directory of Open Access Journals (Sweden)

    Phan Thanh Noi

    2016-12-01

    Full Text Available This study aims to evaluate quantitatively the land surface temperature (LST derived from MODIS (Moderate Resolution Imaging Spectroradiometer MOD11A1 and MYD11A1 Collection 5 products for daily land air surface temperature (Ta estimation over a mountainous region in northern Vietnam. The main objective is to estimate maximum and minimum Ta (Ta-max and Ta-min using both TERRA and AQUA MODIS LST products (daytime and nighttime and auxiliary data, solving the discontinuity problem of ground measurements. There exist no studies about Vietnam that have integrated both TERRA and AQUA LST of daytime and nighttime for Ta estimation (using four MODIS LST datasets. In addition, to find out which variables are the most effective to describe the differences between LST and Ta, we have tested several popular methods, such as: the Pearson correlation coefficient, stepwise, Bayesian information criterion (BIC, adjusted R-squared and the principal component analysis (PCA of 14 variables (including: LST products (four variables, NDVI, elevation, latitude, longitude, day length in hours, Julian day and four variables of the view zenith angle, and then, we applied nine models for Ta-max estimation and nine models for Ta-min estimation. The results showed that the differences between MODIS LST and ground truth temperature derived from 15 climate stations are time and regional topography dependent. The best results for Ta-max and Ta-min estimation were achieved when we combined both LST daytime and nighttime of TERRA and AQUA and data from the topography analysis.

  7. 77 FR 42003 - TA-W-81,263, Chartis Global Services, Inc., a Subsidiary of Chartis, Inc., Regional Processing...

    Science.gov (United States)

    2012-07-17

    ... Employment and Training Administration TA-W-81,263, Chartis Global Services, Inc., a Subsidiary of Chartis, Inc., Regional Processing Organization, Regional Service Center, Houston, TX; TA-W-81,263A, Chartis... certification (TA-W-81,263) to add ``Regional Processing Organization'' and to add workers at an...

  8. Effect of Ta on the microstructure and hardness of Stellite 6 coating deposited by low power pulse laser treatments

    NARCIS (Netherlands)

    Farnia, A.; Ghaini, F. Malek; Rao, J. C.; Ocelik, V.; De Hosson, J. Th M.

    2012-01-01

    Stellite 6 hardfacing alloy with different Ta contents is successfully synthesized with an in situ process on low carbon ferritic steel substrate by Nd:YAG pulsed laser cladding with pre-placed Stellite 6 and Ta mixed powders. The effect of different amounts of Ta on the microstructure of the Stelli

  9. Chromatin modification contributes to the expression divergence of three TaGS2 homoeologs in hexaploid wheat

    Science.gov (United States)

    Zhang, Wei; Fan, Xiaoli; Gao, Yingjie; Liu, Lei; Sun, Lijing; Su, Qiannan; Han, Jie; Zhang, Na; Cui, Fa; Ji, Jun; Tong, Yiping; Li, Junming

    2017-01-01

    Plastic glutamine synthetase (GS2) is responsible for ammonium assimilation. The reason that TaGS2 homoeologs in hexaploid wheat experience different selection pressures in the breeding process remains unclear. TaGS2 were minimally expressed in roots but predominantly expressed in leaves, and TaGS2-B had higher expression than TaGS2-A and TaGS2-D. ChIP assays revealed that the activation of TaGS2-B expression in leaves was correlated with increased H3K4 trimethylation. The transcriptional silencing of TaGS2 in roots was correlated with greater cytosine methylation and less H3K4 trimethylation. Micrococcal nuclease and DNase I accessibility experiments indicated that the promoter region was more resistant to digestion in roots than leaves, which indicated that the closed nucleosome conformation of the promoter region was important to the transcription initiation for the spatial-temporal expression of TaGS2. In contrast, the transcribed regions possess different nuclease accessibilities of three TaGS2 homoeologs in the same tissue, suggesting that nucleosome conformation of the transcribed region was part of the fine adjustment of TaGS2 homoeologs. This study provides evidence that histone modification, DNA methylation and nuclease accessibility coordinated the control of the transcription of TaGS2 homoeologs. Our results provided important evidence that TaGS2-B experienced the strongest selection pressures during the breeding process. PMID:28300215

  10. 78 FR 41954 - TA-W-82,634, Prudential Global Business Technology Solutions Central Security Services Dresher...

    Science.gov (United States)

    2013-07-12

    ... Employment and Training Administration TA-W-82,634, Prudential Global Business Technology Solutions Central Security Services Dresher, Pennsylvania; TA-W-82,634A, Prudential Global Business Technology Solutions Central Security Services Iselin, New Jersey; TA-W-82,634B, Prudential Global Business...

  11. Effect of Ta on the microstructure and hardness of Stellite 6 coating deposited by low power pulse laser treatments

    NARCIS (Netherlands)

    Farnia, A.; Ghaini, F. Malek; Rao, J. C.; Ocelik, V.; De Hosson, J. Th M.

    2012-01-01

    Stellite 6 hardfacing alloy with different Ta contents is successfully synthesized with an in situ process on low carbon ferritic steel substrate by Nd:YAG pulsed laser cladding with pre-placed Stellite 6 and Ta mixed powders. The effect of different amounts of Ta on the microstructure of the

  12. Giant exciton Fano resonance in quasi-one-dimensional Ta2NiSe5

    Science.gov (United States)

    Larkin, T. I.; Yaresko, A. N.; Pröpper, D.; Kikoin, K. A.; Lu, Y. F.; Takayama, T.; Mathis, Y.-L.; Rost, A. W.; Takagi, H.; Keimer, B.; Boris, A. V.

    2017-05-01

    We report the complex dielectric function of the quasi-one-dimensional chalcogenide Ta2NiSe5 , which undergoes a structural phase transition presumably associated with exciton condensation below Tc=326 K [Y. Wakisaka et al., Phys. Rev. Lett. 103, 026402 (2009), 10.1103/PhysRevLett.103.026402; Y. F. Lu et al., Nat. Commun. 8, 14408 (2017), 10.1038/ncomms14408], and of the isostructural Ta2NiS5 , which does not exhibit such a transition. Using spectroscopic ellipsometry, we have detected exciton doublets with pronounced Fano line shapes in both the compounds. The exciton Fano resonances in Ta2NiSe5 display an order-of-magnitude higher intensity than those in Ta2NiS5 . In conjunction with prior theoretical work [E. Rashba, Sov. Phys. Semicond. 8, 807 (1975)], we attribute this observation to the giant oscillator strength of spatially extended exciton-phonon bound states in Ta2NiSe5 . The formation of exciton-phonon complexes in Ta2NiS5 and Ta2NiSe5 is confirmed by the pronounced temperature dependence of sharp interband transitions in the optical spectra, the peak energies and widths of which scale with the thermal population of optical phonon modes. The description of the optically excited states in terms of strongly overlapping exciton complexes is in good agreement with the hypothesis of an exciton insulator ground state.

  13. Consolidation of B4C-TaB2 eutectic composites by spark plasma sintering

    Directory of Open Access Journals (Sweden)

    Dmytro Demirskyi

    2015-12-01

    Full Text Available The in situ synthesis/consolidation of B4C-TaB2 eutectic composites by spark plasma sintering (SPS is reported. The microstructure–property relations were determined for composites with the B4C-TaB2 eutectic composition as functions of TaB2 content, and TaB2-TaB2 interlamellar spacing. A clear maximum in fracture toughness was identified (∼4.5 MPa m1/2 for eutectic composites with interlamellar spacing between 0.9 and 1.1 μm. The composites with the hypereutectic composition of 40 mol.% TaB2 obtained by SPS exhibited lower Vickers hardness (25–26 GPa but higher indentation fracture toughness (up to 4.9 MPa m1/2 than eutectic composites with 30–35 mol.% of TaB2.

  14. The Dilatometric Analysis of the High Carbon Alloys from Ni-Ta-Al-M System

    Directory of Open Access Journals (Sweden)

    Bała P.

    2014-10-01

    Full Text Available In the following work presents results of high carbon alloys from the Ni-Ta-Al-M system are presented. The alloys have been designed to have a good tribological properties at elevated temperatures. Despite availability of numerous hot work tool materials there is still a growing need for new alloys showing unique properties, which could be used under heavy duty conditions, i.e. at high temperatures, in a chemically aggressive environment and under heavy wear conditions. A characteristic, coarse-grained dendritic microstructure occurs in the investigated alloys in the as-cast condition. Primary dendrites with secondary branches can be observed. Tantalum carbides of MC type and graphite precipitations are distributed in interdendritic spaces in the Ni-Ta-Al-C and Ni-Ta-Al-C-Co alloys, while Tantalum carbides of MC type and Chromium carbides of M7C3 type appeared in the Ni-Ta-Al-C-Co-Cr and Ni-Ta-Al-C-Cr alloys. In all alloys g’ phase is present, however, its volume fraction in the Ni-Ta-Al-C and Ni-Ta-Al-C-Co alloys is small.

  15. Theoretical study of water adsorption and dissociation on Ta3N5(100) surfaces.

    Science.gov (United States)

    Wang, Jiajia; Luo, Wenjun; Feng, Jianyong; Zhang, Li; Li, Zhaosheng; Zou, Zhigang

    2013-10-14

    Water adsorption and dissociation on the perfect, oxygen containing and nitrogen vacancy containing Ta3N5(100) surfaces are systematically studied by density functional theory calculations. The results show that the perfect Ta3N5(100) surface is very active for water dissociation because of the dangling bonds formed on the perfect Ta3N5(100) surface. The presence of oxygen on the surface is able to stabilize the Ta3N5(100) surface but not to facilitate water dissociation, which may be ascribed to the saturation of surface dangling bonds by oxygen. The presence of a nitrogen vacancy on the surface is able to facilitate water dissociation, but Ta3N5(100) surfaces with nitrogen vacancies are not stable. We found that keeping the impurity oxygen as less as possible is one effective approach to enhance the water splitting ability of Ta3N5. We propose that doping with foreign elements is one potential method to obtain a clean Ta3N5(100) surface, since the oxygen concentration may be adjusted by competition between oxygen and foreign elements.

  16. First-principles study of the structural stability and electronic structures of TaN

    Energy Technology Data Exchange (ETDEWEB)

    Cao, C.L.; Yuan, G. [School of Information and Engineering, Ocean University of China, QingDao 266100 (China); Hou, Z.F. [Department of Physics, Fudan University, Shanghai 200433 (China)

    2008-08-15

    Using the plane-wave pseudopotential method within the generalized gradient approximation, we have studied the structural stability and electronic structures for several TaN phases. Our results show CoSn is the calculated ground-state structure of TaN among the five crystallographic structures that have been studied. The order of energetic stability of phase structures of TaN from low to high is: CsClTaN in the CoSn and WC structures is due to the formation of pseudogap around the Fermi level and the stronger hybridization between N-2p states and Ta-5d states. TaN in all structures studied has a metallic nature. The calculated bulk modulus indicates that TaN in the WC structure may be a less compressible material. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  17. Transformation,Deformation and Microstructure Characteristics of Ru50Ta50 High Temperature Shape Memory Alloy

    Institute of Scientific and Technical Information of China (English)

    Zhirong HE; Fang WANG; Jing'en ZHOU

    2006-01-01

    The basic martensitic transformation(MT)properties of Ru50Ta50 alloy, i.e. MT temperature(MTT), temperature hysteresis(△T), and MT heat(△H)were investigated in this paper. The effects of heat treatment and thermal cycling on MT behavior of Ru50Ta50 alloy, the deformation and microstructure characteristics of Ru50Ta50 alloy were also studied for its engineering application as high temperature actuator/sensor materials by means of differential scanning calorimetry, X-ray diffraction, transmission electron microscope, optical microscope, and hardness test. The results showed that a two-stage reversible MT takes place in Ru50Ta50 alloy.The two-stage MT starting temperatures(M1s, M2s)and the temperature hysteresis(△T1, △T2)are 1047,784 and 11, 14℃, respectively. No significant effect of aging treatment and thermal cycling on MTT and △T of Ru50Ta50 alloy were observed, but △H decreases slowly with increasing thermal cycles. The hardness and brittleness of Ru50Ta50 alloy are high. The deformation mode of RuTa alloys is twinning.

  18. Consolidation of W–Ta composites: Hot isostatic pressing and spark and pulse plasma sintering

    Energy Technology Data Exchange (ETDEWEB)

    Dias, M., E-mail: marta.dias@itn.pt [Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa (Portugal); Guerreiro, F. [Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa (Portugal); Correia, J.B. [LNEG, Laboratório Nacional de Energia e Geologia, Estrada do Paço do Lumiar, 1649-038 Lisboa (Portugal); Galatanu, A. [National Institute of Materials Physics, Atomistilor 105 bis Bucharest-Magurele, 077125 Ilfov (Romania); Rosiński, M. [Warsaw University of Technology, Faculty of Materials Science and Engineering, Warsaw (Poland); Monge, M.A.; Munoz, A. [Departamento de Física, Univerdidad Carlos III de Madrid, Avd. de la Universidad 30, 28911 Madrid (Spain); Alves, E. [Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa (Portugal); Carvalho, P.A. [Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa (Portugal); CeFEMA, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa (Portugal)

    2015-10-15

    Highlights: • Consolidation of W–Ta composites using three techniques: HIP, SPS and PPS. • Comparison of consolidation methods in terms of W–Ta interdiffusion and densification. • Microstructure analysis in terms of oxides formation. - Abstract: Composites consisting of tantalum fiber/powder dispersed in a nanostructured W matrix have been consolidated by spark and pulse plasma sintering as well as by hot isostatic pressing. The microstructural observations revealed that the tungsten–tantalum fiber composites consolidated by hot isostatic pressing and pulse plasma sintering presented a continuous layer of Ta{sub 2}O{sub 5} phase at the W/Ta interfaces, while the samples consolidated by spark plasma sintering evidenced a Ta + Ta{sub 2}O{sub 5} eutectic mixture due to the higher temperature of this consolidation process. Similar results have been obtained for the tungsten–tantalum powder composites. A (W, Ta) solid solution was detected around the prior nanostructured W particles in tungsten–tantalum powder composites consolidated by spark and pulse plasma sintering. Higher densifications were obtained for composites consolidated by hot isostatic pressing and pulse plasma sintering.

  19. Structures, Phase Transformations, and Dielectric Properties of BiTaO4 Ceramics.

    Science.gov (United States)

    Zhou, Di; Fan, Xiao-Qin; Jin, Xiao-Wei; He, Duan-Wei; Chen, Guo-Hua

    2016-11-21

    Low (α)- and high-temperature (β) forms of BiTaO4 have attracted much attention due to their dielectric and photocatalytic properties. In the present work, a third form, the so-called HP-BiTaO4, was synthesized at high temperature and pressure. The phase evolution, phase transformations, and dielectric properties of α- and β-BiTaO4 and HP-BiTaO4 ceramics are studied in detail. β-BiTaO4 ceramics densified at 1300 °C with the microwave permittivity εr ≈ 53, the microwave quality factor Qf ≈ 12070 GHz, and the temperature coefficient of resonant frequency τf ≈ -200 ppm/°C. HP-BiTaO4 ceramics were synthesized at 5 GPa and 1300 °C followed by annealing at 600 °C. In contrast with the α phase, HP-BiTaO4 exhibited εr ≈ 195 at 1 kHz to 10 MHz, accompanied by a low dielectric loss of ∼0.004. The relation between structure and dielectric properties is discussed in the context of Shannon's additive rule and bond theory.

  20. Mechanism of n-butane hydrogenolysis promoted by Ta-hydrides supported on silica

    KAUST Repository

    Pasha, Farhan Ahmad

    2014-06-06

    The mechanism of hydrogenolysis of alkanes, promoted by Ta-hydrides supported on silica via 2 ≡ Si-O- bonds, has been studied with a density functional theory (DFT) approach. Our study suggests that the initial monohydride (≡ Si-O-)2Ta(III)H is rapidly trapped by molecular hydrogen to form the more stable tris-hydride (≡ Si-O-) 2Ta(V)H3. Loading of n-butane to the Ta-center occurs through C-H activation concerted with elimination of molecular hydrogen (σ-bond metathesis). Once the Ta-alkyl species is formed, the C-C activation step corresponds to a β-alkyl transfer to the metal with elimination of an olefin. According to these calculations, an α-alkyl transfer to the metal to form a Ta-carbene species is of higher energy. The olefins formed during the C-C activation step can be rapidly hydrogenated by both mono- and tris-Ta-hydride species, making the overall process of alkane cracking thermodynamically favored. © 2014 American Chemical Society.

  1. The physical properties of cubic plasma-enhanced atomic layer deposition TaN films

    Science.gov (United States)

    Kim, H.; Lavoie, C.; Copel, M.; Narayanan, V.; Park, D.-G.; Rossnagel, S. M.

    2004-05-01

    Plasma-enhanced atomic layer deposition (PE-ALD) is a promising technique to produce high quality metal and nitride thin films at low growth temperature. In this study, very thin (<10 nm) low resistivity (350 μΩ cm) cubic TaN Cu diffusion barrier were deposited by PE-ALD from TaCl5 and a plasma of both hydrogen and nitrogen. The physical properties of TaN thin films including microstructure, conformality, roughness, and thermal stability were investigated by various analytical techniques including x-ray diffraction, medium energy ion scattering, and transmission electron microscopy. The Cu diffusion barrier properties of PE-ALD TaN thin films were studied using synchrotron x-ray diffraction, optical scattering, and sheet resistance measurements during thermal annealing of the test structures. The barrier failure temperatures were obtained as a function of film thickness and compared with those of PE-ALD Ta, physical vapor deposition (PVD) Ta, and PVD TaN. A diffusion kinetics analysis showed that the microstructure of the barrier materials is one of the most critical factors for Cu diffusion barrier performance.

  2. Synthesis and characterization of Cu{sub 3}TaIn{sub 3}Se{sub 7} and CuTa{sub 2}InTe{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Calderon, E.; Munoz-Pinto, M.; Duran-Pina, S.; Quintero, M.; Quintero, E.; Morocoima, M. [Centro de Estudios de Semiconductores, Departamento de Fisica, Facultad de Ciencias, Universidad de Los Andes, Merida (Venezuela); Delgado, G.E. [Laboratorio de Cristalografia, Departamento de Quimica, Facultad de Ciencias, Universidad de Los Andes, Merida (Venezuela); Romero, H. [Laboratorio de Magnetismo, Departamento de Fisica, Facultad de Ciencias, Universidad de Los Andes, Merida (Venezuela); Briceno, J.M.; Fernandez, J. [Laboratorio de Analisis Quimico y Estructural (LAQUEM), Departamento de Fisica, Facultad de Ciencias, Merida (Venezuela); Grima-Gallardo, P.

    2008-07-15

    Polycrystalline samples of Cu{sub 3}TaIn{sub 3}Se{sub 7} and CuTa{sub 2}InTe{sub 4} were synthesized by the usual melt and anneal technique. X-ray powder diffraction showed a single phase behavior for both samples with tetragonal symmetry and unit cell parameter values a=5.794{+-}0.002 A, c=11.66{+-}0.01 A, c/a=2.01, V=391{+-}1 A{sup 3} and a=6.193{+-}0.001 A, c=12.400 {+-}0.002A, c/a=2.00, V=475{+-}1 A{sup 3}, respectively. Differential thermal analysis (DTA) measurements suggested a complicated behavior near the melting point with several thermal transitions observed in the heating and cooling runs. From the shape of the DTA peaks it was deduced that the melting is incongruent for both materials. Magnetic susceptibility measurements (zero-field cooling and field cooling) indicated an antiferromagnetic character with transition temperatures of T=70 K (Cu{sub 3}TaIn{sub 3}Se{sub 7}) and 42 K (CuTa{sub 2}InTe{sub 4}). A spin-glass transition was observed in Cu{sub 3}TaIn{sub 3}Se{sub 7} with T{sub f}{approx}50 K. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  3. Study of XANES near Ta-L edges in LiTaO{sub 3} through thermal wave, fluorescence and first principles

    Energy Technology Data Exchange (ETDEWEB)

    Kane, S.R.; Singh, Ajit Kumar [Raja Ramanna Centre for Advanced Technology, Indus Synchrotrons Utilisation Division, Indore (India); Kumar, Shailendra; Ghosh, Haranath; Tiwari, M.K. [Raja Ramanna Centre for Advanced Technology, Indus Synchrotrons Utilisation Division, Indore (India); BARC, Homi Bhabha National Institute, Mumbai (India)

    2016-01-15

    X-ray absorption near-edge spectra (XANES) of Ta-L{sub 2} and L{sub 3} edges in LiTaO{sub 3} (LTO) crystals are measured by measuring amplitude and phase of thermal waves generated within the LTO crystal, using pyroelectric property of LTO. Thus, LTO crystal is used both as a sample as well as sensor material. XANES of Ta-L edges in LTO are also measured by fluorescence. XANES spectra from fluorescence and first-principles simulations agree excellently well. The onset of the pre-edge region of XANES, measured by both techniques, extends below the edge by about 50 eV. This pre-edge onset of absorption is explained in terms of the core-hole lifetime effect on near-edge absorption using density functional theory. However, detailed nature of XANES peaks near Ta-L{sub 3} and Ta-L{sub 2} absorption edges, measured by thermal waves and fluorescence, differ. Possible origins of these differences are discussed. (orig.)

  4. Chemical Concentrations in Field Mice from Open-Detonation Firing Sites TA-36 Minie and TA-39 Point 6 at Los Alamos National Laboratory

    Energy Technology Data Exchange (ETDEWEB)

    Fresquez, Philip R. [Los Alamos National Laboratory

    2011-01-01

    Field mice (mostly Peromyscus spp.) were collected at two open-detonation (high explosive) firing sites - Minie at Technical Area (TA) 36 and Point 6 at TA-39 - at Los Alamos National Laboratory in August of 2010 and in February of 2011 for chemical analysis. Samples of whole body field mice from both sites were analyzed for target analyte list elements (mostly metals), dioxin/furans, polychlorinated biphenyl congeners, high explosives, and perchlorate. In addition, uranium isotopes were analyzed in a composite sample collected from TA-36 Minie. In general, all constituents, with the exception of lead at TA-39 Point 6, in whole body field mice samples collected from these two open-detonation firing sites were either not detected or they were detected below regional statistical reference levels (99% confidence level), biota dose screening levels, and/or soil ecological chemical screening levels. The amount of lead in field mice tissue collected from TA-39 Point 6 was higher than regional background, and some lead levels in the soil were higher than the ecological screening level for the field mouse; however, these levels are not expected to affect the viability of the populations over the site as a whole.

  5. Phase relations and crystal structures in the system Ta-V-Ge.

    Science.gov (United States)

    Khan, Atta U; Bursik, J; Rogl, P

    2012-05-28

    Phase equilibria have been derived for the isothermal section of the Ta-V-Ge system at 1500 °C (for concentrations phases have been identified within the isothermal section, out of which three were characterized by Rietveld refinement of X-ray powder diffraction data. τ(1)-(Ta(1-x)V(x))(5)Ge(3) (0.21 ≤ x ≤ 0.63) adopts the Mn(5)Si(3)-type and τ(2)-Ta(Ta(x)V(1-x-y)Ge(y))(2), x = 0.02, y = 0.12 was found to be a MgZn(2)-type Laves phase. Detailed transmission electron microscopy (TEM) in several crystallographic directions confirmed lattice parameters and crystal symmetry of this phase and rejected the presence of any superstructure. τ(3)-Ta(9-x+y)V(4+x-y-z)Ge(1+z), x = 0.32, y = 0.51, z = 0.98 crystallizes with the Nb(9)Co(4)Ge-type, whereas the structure of τ(4) is not yet known. Although a MgCu(2)-type cubic Laves phase is not present in the Ta-V binary at this temperature, additions of Ge stabilize this phase in the ternary system: C15-Ta(Ta(x)V(1-x-y)Ge(y))(2), x = 0.04, y = 0.05. V(11)Ge(8) (Cr(11)Ge(8) type) shows a large solubility up to (Ta(x)V(1-x))(11)Ge(8), x = 0.64 at 1500 °C.

  6. Determination of the effective quadrupole moment in $^{181}$Ta with pionic x-rays

    CERN Document Server

    Beetz, R; Fransson, K; Konijn, J; Panman, J; Tauscher, Ludwig; Tibell, G

    1978-01-01

    From the hyperfine splitting of the 5g to 4f and the 6g to 4f pionic X-rays in /sup 181/Ta, an effective quadrupole moment of Q/sub eff /=3.58+or-0.03 b was determined. The strong interaction monopole shift epsilon /sub 0/ and the width Gamma /sub 0/ of the 4f level were measured to be epsilon /sub 0/=540+or-100 eV and Gamma /sub 0 /=225+or-57 eV, in good agreement with the values obtained with the standard optical potential description of the pion-nucleus interaction. Estimating the influence of the finite nuclear size, the deformation induced through the strong interaction between the pion and the finite nucleus, and the relative magnitude between the strong and the electromagnetic quadrupole coupling constants values for the spectroscopic quadrupole moment of Q=3.30+or-0.06 b, and for the intrinsic quadrupole moment of Q/sub 0/=7.06+or-0.12 b are obtained. (28 refs).

  7. Bitcoin - alternatīva valūta

    OpenAIRE

    Liškovska, Eva

    2014-01-01

    Mūsdienās digitālās valūtas kļūst ar vien izplatītākas, tādēļ autore ir izvēlējusies pētīt digitālo valūtu Bitcoin. Maģistra darba mērķis ir izanalizēt, kādas ir Bitcoin valūtas priekšrocības un trūkumi, lai izdarītu secinājumus un izstrādātu priekšlikumus Bitcoin uzlabošanai, lai nākotnē tā spētu būt tikpat konkurētspējīga kā reālā valūta. Pēc pētījuma veikšanas autore secināja, ka Bitcoin popularitāte gan lietotāju vidū, gan uzņēmumu vidū, kas sāk pieņemt Bitcoin digotālo valūtu, tikai t...

  8. Biocompatibility of new Ti-Nb-Ta base alloys.

    Science.gov (United States)

    Hussein, Abdelrahman H; Gepreel, Mohamed A-H; Gouda, Mohamed K; Hefnawy, Ahmad M; Kandil, Sherif H

    2016-04-01

    β-type titanium alloys are promising materials in the field of medical implants. The effect of β-phase stability on the mechanical properties, corrosion resistance and cytotoxicity of a newly designed β-type (Ti77Nb17Ta6) biocompatible alloys are studied. The β-phase stability was controlled by the addition of small quantities of Fe and O. X-ray diffraction and microstructural analysis showed that the addition of O and Fe stabilized the β-phase in the treated solution condition. The strength and hardness have increased with the increase in β-phase stability while ductility and Young's modulus have decreased. The potentio-dynamic polarization tests showed that the corrosion resistance of the new alloys is better than Ti-6Al-4V alloy by at least ten times. Neutral red uptake assay cytotoxicity test showed cell viability of at least 95%. The new alloys are promising candidates for biomedical applications due to their high mechanical properties, corrosion resistance, and reduced cytotoxicity.

  9. Biocompatibility of new Ti–Nb–Ta base alloys

    Energy Technology Data Exchange (ETDEWEB)

    Hussein, Abdelrahman H. [Department of Materials Science, Institute of Graduate Studies and Research, Alexandria University, Alexandria (Egypt); Gepreel, Mohamed A.-H.; Gouda, Mohamed K. [Department of Materials Science and Engineering, Egypt–Japan University of Science and Technology, Alexandria (Egypt); Hefnawy, Ahmad M.; Kandil, Sherif H. [Department of Materials Science, Institute of Graduate Studies and Research, Alexandria University, Alexandria (Egypt)

    2016-04-01

    β-type titanium alloys are promising materials in the field of medical implants. The effect of β-phase stability on the mechanical properties, corrosion resistance and cytotoxicity of a newly designed β-type (Ti{sub 77}Nb{sub 17}Ta{sub 6}) biocompatible alloys are studied. The β-phase stability was controlled by the addition of small quantities of Fe and O. X-ray diffraction and microstructural analysis showed that the addition of O and Fe stabilized the β-phase in the treated solution condition. The strength and hardness have increased with the increase in β-phase stability while ductility and Young's modulus have decreased. The potentio-dynamic polarization tests showed that the corrosion resistance of the new alloys is better than Ti–6Al–4V alloy by at least ten times. Neutral red uptake assay cytotoxicity test showed cell viability of at least 95%. The new alloys are promising candidates for biomedical applications due to their high mechanical properties, corrosion resistance, and reduced cytotoxicity. - Highlights: • The properties and biocompatibility of new titanium alloys for biomedical applications were investigated. • Biocompatibility is excellent compared to Ti-6Al-4V in terms of a lower young's modulus and better corrosion resistance. • The newly designed alloys have good strength and lower Young's modulus combined with excellent corrosion resistance. • The new alloys have a strong potential for biomedical applications.

  10. Laser-deposited Ti-Nb-Zr-Ta orthopedic alloys.

    Science.gov (United States)

    Banerjee, R; Nag, S; Samuel, S; Fraser, H L

    2006-08-01

    The complex quaternary Ti-35Nb-7Zr-5Ta orthopedic alloy has been successfully deposited from a powder feedstock consisting of a blend of elemental titanium, niobium, zirconium, and tantalum powders, using the laser engineered net-shaping (LENStrade mark) process. In the as laser-deposited form, these alloys exhibit a substantially higher tensile strength as compared with more conventionally processed counterparts of similar composition, while maintaining excellent ductility and a low modulus. Furthermore, the as-deposited alloys appear to exhibit a texture, with a substantially large number of grains of the beta phase aligning one of their axes nearly normal to the substrate or parallel to the growth direction. The microstructure of the as-deposited as well as tensile-tested alloys have been characterized in detail using scanning electron microscopy (SEM), orientation microscopy (OM), and transmission electron microscopy (TEM). Formation of a high density of shear bands, possibly arising from slip localization due to precipitates of the omega phase in the beta matrix, is clearly evident in the tensile-tested sample. The enhanced tensile strength and low modulus in these laser-deposited alloys coupled with the ability to form near-net shape components makes LENS an attractive processing technology for orthopedic implants.

  11. LAFD: TA-16 HE Facility Familiarization Tour, OJT 55258

    Energy Technology Data Exchange (ETDEWEB)

    Rutherford, Victor Stephen [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-05-31

    Los Alamos National Laboratory (LANL) will conduct familiarization tours for personnel of the Los Alamos County Fire Department (LAFD) at TA-16 high explosives (HE) facilities. These familiarization tours are official LANL business; the purpose of these tours is to orient LAFD firefighters to the facility so that they can respond efficiently and quickly to a variety of emergency situations. This orientation includes, among other topics, ingress and egress of the area and buildings, layout and organization of the facility, evacuation procedures and assembly points, and areas of concern within the various buildings at the facility. LAFD firefighters have the skills and abilities to perform firefighting operations and other emergency response tasks that cannot be provided by LANL personnel who have the required clearance. This handout provides details of the information, along with maps and diagrams, to be presented during the familiarization tours. The handout will be distributed to the trainees at the time of the tour. A corresponding checklist will also be used as guidance during the familiarization tours to ensure that all required information is presented to LAFD personnel.

  12. Dynamic surface tension of surfactant TA: experiments and theory.

    Science.gov (United States)

    Otis, D R; Ingenito, E P; Kamm, R D; Johnson, M

    1994-12-01

    A bubble surfactometer was used to measure the surface tension of an aqueous suspension of surfactant TA as a function of bubble area over a range of cycling rates and surfactant bulk concentrations. Results of the surface tension-interfacial area loops exhibited a rich variety of phenomena, the character of which varied systematically with frequency and bulk concentration. A model was developed to interpret and explain these data and for use in describing the dynamics of surface layers under more general circumstances. Surfactant was modeled as a single component with surface tension taken to depend on only the interfacial surfactant concentration. Two distinct mechanisms were considered for the exchange of surfactant between the bulk phase and interface. The first is described by a simple kinetic relationship for adsorption and desorption that pertains only when the interfacial concentration is below its maximum equilibrium value. The second mechanism is "squeeze-out" by which surfactant molecules are expelled from an interface compressed past a maximum packing state. The model provided good agreement with experimental measurements for cycling rates from 1 to 100 cycles/min and for bulk concentrations between 0.0073 and 7.3 mg/ml.

  13. The JEM-EUSO prototype telescope TA-EUSO

    Energy Technology Data Exchange (ETDEWEB)

    Bisconti, Francesca; Haungs, Andreas; Kang, Donghwa; Karus, Michael [Institut fuer Kernphysik (IKP), Karlsruher Institut fuer Technologie (KIT) (Germany); Bluemer, Johannes [Institut fuer Kernphysik (IKP), Karlsruher Institut fuer Technologie (KIT) (Germany); Institut fuer Experimentelle Kernphysik (IEKP), KIT (Germany); Huber, Thomas [Institut fuer Experimentelle Kernphysik (IEKP), KIT (Germany); Collaboration: JEM-EUSO-Collaboration

    2015-07-01

    JEM-EUSO (Extreme Universe Space Observatory onboard Japanese Experiment Module) is an Ultra High-Energy Cosmic Rays (UHECRs) detector under development, sensitive to the fluorescence emission of extensive air showers in the Earth's atmosphere, looking down from the International Space Station. In this way, it will provide a large field of view and therefore about tenfold better statistics for UHECRs than with ground-based observatories. To validate the design of such a space based telescope, one of the prototypes under development is EUSO-TA, at the Telescope Array site (Utah). This prototype will give information about the calibration of the Fresnel lense system and the Photo Detector Module (PDM), both basic parts of JEM-EUSO. One PDM currently consists of 36 Multi-Anode Photomultiplier Tubes from Hamamatsu. Silicon Photo-Multipliers (SiPMs) are under consideration for the realization of a PDM, benefiting from the practical advantages as excellent photon counting capability and time resolution, high gain, low operating voltage, robustness and compactness. The response of this sensor type is investigated by simulations and in the laboratory.

  14. Ta/TA6V heterogeneous welding. Study of the formation and the metallurgical properties of the melted zones; Soudage heterogene Ta/TA6V Etude de la formation et des proprietes metallurgiques des zones fondues

    Energy Technology Data Exchange (ETDEWEB)

    Malicrot, A.; Naudy, P.; Durut, L. [CEA Valduc, 21120 Is-sur-Tille (France); Grevey, D. [Pole Laser Creusot Bourgogne, 71200 Le Creusot (France); Daloz, D. [Ecole des Mines de Nancy, 54000 Nancy (France)

    2006-07-01

    The welding laboratory of the department of manufacturing and nuclear technologies is in charge to assemble prototype objects which appeal to a lot of materials as for instance titanium or tantalum. The autogenous weldability of these two materials is relatively well known nowadays, by laser beam or electrons beam. On the other hand, the heterogeneous welding is most difficult on account of the important differences of the thermophysical and metallurgical properties of the two involved materials. This work deals more particularly with the Nd:YAG laser welding of tantalum with the titanium alloy TA6V. Two modes of energy contribution are considered: impulsional and continuous. The aim of this work is to finely characterized, in a metallurgical point of view, the melted zones in order to control their composition (constitution and distribution of the phases in presence, identification of the eventual defects), as well as the reactional processes occurring in the liquid bath during and after the interaction of the laser beam with the matter. Thus, a first study has been carried out at the macroscopic scale in order to obtain global views of the melted zones. The magnification is then strongly increased for analyzing the weldings at the microstructure scale. (O.M.)

  15. Effect of TaC Particles Dissolution on Grain Coarsening in Reduced Activation Steels

    Institute of Scientific and Technical Information of China (English)

    XIA Zhi-xin; ZHANG Chi; HUANG Qun-ying; LIU Shao-jun; LI Zhao-dong; YANG Zhi-gang

    2011-01-01

    The effect of TaC on grains and packets coarsening in the reduced activation ferritic/martensitic (RAFM) steels was investigated. It was found that the combined effect of the austenitizing temperature and heating rate resulted in the heterogeneous austenite grain growth. When the austenitizing temperature was raised above 1 423 K, the TaC particles disappeared, and the homogenous grains abruptly increased. The thermodynamic model for dissolution of TaC particles during austenitizing was applied to interpret the results.

  16. Low External Electric Field Periodic Poling of Thick LiTaO3

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    A promising method of ferroelectric domain inverted structures was demonstrated, which allows us to fabricate thicker domain inverted patterns by applying a lower external electric field in LiTaO3 crystal. The external field for the domain reversal of the 1.5 mm thick LiTaO3 at 500 ℃ was only 6 V·mm-1, which is lower by three orders of magnitude than that in LiTaO3 crystal at room temperature. The process of the domain inversion structure was also studied. The fabrication techniques are based on controlled temperature and field duration time.

  17. Application of LiTaO3 pyroelectric crystal for pulsed neutron detection

    Science.gov (United States)

    Liang, W. F.; Lu, Y.; Wu, J.; Gao, H.; Li, M.

    2016-08-01

    The feasibility of a LiTaO3 pyroelectric crystal for pulsed neutron detection has been studied. The detector consists of a slice of electroded Z-cut LiTaO3 pyroelectric crystal, and no additional neutron converter is required owing to the Li contained in the crystal. The slight temperature increase caused by neutron radiation will lead to the release of bound charges and will give rise to a pyroelectric signal. The response of it has been studied both theoretically and experimentally. Our preliminary experiment on the CFBR-II reactor suggests that the LiTaO3 pyroelectric detector is promising for high intensity neutron - pulse measurement.

  18. Nanostructured Ti-Ta thin films synthesized by combinatorial glancing angle sputter deposition.

    Science.gov (United States)

    Motemani, Yahya; Khare, Chinmay; Savan, Alan; Hans, Michael; Paulsen, Alexander; Frenzel, Jan; Somsen, Christoph; Mücklich, Frank; Eggeler, Gunther; Ludwig, Alfred

    2016-12-09

    Ti-Ta alloys are attractive materials for applications in actuators as well as biomedical implants. When fabricated as thin films, these alloys can potentially be employed as microactuators, components for micro-implantable devices and coatings on surgical implants. In this study, Ti100-x Ta x (x = 21, 30) nanocolumnar thin films are fabricated by glancing angle deposition (GLAD) at room temperature using Ti73Ta27 and Ta sputter targets. Crystal structure, morphology and microstructure of the nanostructured thin films are systematically investigated by XRD, SEM and TEM, respectively. Nanocolumns of ∼150-160 nm in width are oriented perpendicular to the substrate for both Ti79Ta21 and Ti70Ta30 compositions. The disordered α″ martensite phase with orthorhombic structure is formed in room temperature as-deposited thin films. The columns are found to be elongated small single crystals which are aligned perpendicular to the [Formula: see text] and [Formula: see text] planes of α″ martensite, indicating that the films' growth orientation is mainly dominated by these crystallographic planes. Laser pre-patterned substrates are utilized to obtain periodic nanocolumnar arrays. The differences in seed pattern, and inter-seed distances lead to growth of multi-level porous nanostructures. Using a unique sputter deposition geometry consisting of Ti73Ta27 and Ta sputter sources, a nanocolumnar Ti-Ta materials library was fabricated on a static substrate by a co-deposition process (combinatorial-GLAD approach). In this library, a composition spread developed between Ti72.8Ta27.2 and Ti64.4Ta35.6, as confirmed by high-throughput EDX analysis. The morphology over the materials library varies from well-isolated nanocolumns to fan-like nanocolumnar structures. The influence of two sputter sources is investigated by studying the resulting column angle on the materials library. The presented nanostructuring methods including the use of the GLAD technique along with pre

  19. Nanostructured Ti-Ta thin films synthesized by combinatorial glancing angle sputter deposition

    Science.gov (United States)

    Motemani, Yahya; Khare, Chinmay; Savan, Alan; Hans, Michael; Paulsen, Alexander; Frenzel, Jan; Somsen, Christoph; Mücklich, Frank; Eggeler, Gunther; Ludwig, Alfred

    2016-12-01

    Ti-Ta alloys are attractive materials for applications in actuators as well as biomedical implants. When fabricated as thin films, these alloys can potentially be employed as microactuators, components for micro-implantable devices and coatings on surgical implants. In this study, Ti100-x Ta x (x = 21, 30) nanocolumnar thin films are fabricated by glancing angle deposition (GLAD) at room temperature using Ti73Ta27 and Ta sputter targets. Crystal structure, morphology and microstructure of the nanostructured thin films are systematically investigated by XRD, SEM and TEM, respectively. Nanocolumns of ˜150-160 nm in width are oriented perpendicular to the substrate for both Ti79Ta21 and Ti70Ta30 compositions. The disordered α″ martensite phase with orthorhombic structure is formed in room temperature as-deposited thin films. The columns are found to be elongated small single crystals which are aligned perpendicular to the (20\\bar{4}) and (204) planes of α″ martensite, indicating that the films’ growth orientation is mainly dominated by these crystallographic planes. Laser pre-patterned substrates are utilized to obtain periodic nanocolumnar arrays. The differences in seed pattern, and inter-seed distances lead to growth of multi-level porous nanostructures. Using a unique sputter deposition geometry consisting of Ti73Ta27 and Ta sputter sources, a nanocolumnar Ti-Ta materials library was fabricated on a static substrate by a co-deposition process (combinatorial-GLAD approach). In this library, a composition spread developed between Ti72.8Ta27.2 and Ti64.4Ta35.6, as confirmed by high-throughput EDX analysis. The morphology over the materials library varies from well-isolated nanocolumns to fan-like nanocolumnar structures. The influence of two sputter sources is investigated by studying the resulting column angle on the materials library. The presented nanostructuring methods including the use of the GLAD technique along with pre-patterning and a

  20. Formation of titanium dioxide nanotubes on Ti–30Nb–xTa alloys by anodizing

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Eun-Sil [Department of Dental Materials and Research Center of Nano-Interface Activation for Biomaterials, School of Dentistry, Chosun University, Gwangju (Korea, Republic of); Jeong, Yong-Hoon [Department of Dental Materials and Research Center of Nano-Interface Activation for Biomaterials, School of Dentistry, Chosun University, Gwangju (Korea, Republic of); Biomechanics and Tissue Engineering Laboratory, Division of Orthodontics, College of Dentistry, The Ohio State University, Columbus, OH (United States); Choe, Han-Cheol, E-mail: hcchoe@chosun.ac.kr [Department of Dental Materials and Research Center of Nano-Interface Activation for Biomaterials, School of Dentistry, Chosun University, Gwangju (Korea, Republic of); Brantley, William A. [Division of Restorative, Prosthetic and Primary Care Dentistry, College of Dentistry, The Ohio State University, Columbus, OH (United States)

    2013-12-31

    The goal of this study was to investigate the formation of titanium dioxide nanotubes on the surface of cast Ti–30Nb–xTa alloys by anodizing. The anodization technique for creating the nanotubes utilized a potentiostat and an electrolyte containing 1 M H{sub 3}PO{sub 4} with 0.8 wt.% NaF. The grain size of the Ti–30Nb–xTa alloys increased as the Ta content increased. Using X-ray diffraction, for the Ti–30Nb alloy the main peaks were identified as α″ martensite with strong peaks of β phase. The phases in the Ti–30Nb–xTa alloys changed from a duplex (α″ + β) microstructure to solely β phase with increasing Ta content. The nanotubes that formed on the surface of the Ti–30Nb–xTa alloys were amorphous TiO{sub 2} without an evidence of the crystalline anatase or rutile forms of TiO{sub 2}. Scanning electron microscopy revealed that the average diameters of the small and large nanotubes on the Ti–30Nb alloy not containing Ta were approximately 100 nm and 400 nm, respectively, whereas the small and large nanotubes on the alloy had diameters of approximately 85 nm and 300 nm, respectively. As the Ta content increased from 0 to 15 wt.%, the average lengths of the nanotubes increased from 2 μm to 3.5 μm. Energy-dispersive X-ray spectroscopy indicated that the nanotubes were principally composed of Ti, Nb, Ta, O and F. Contact angle measurements showed that the nanotube surface had good wettability by water droplets. - Highlights: • TiO{sub 2} nanotube layers on anodized Ti-30Nb-xTa alloys have been investigated. • Nanotube surface had an amorphous structure without heat treatment. • Nanotube diameter of Ti-30Nb-xTa decreased, whereas tube layer increased with Ta content. • The nanotube surface exhibited the low contact angle and good wettability.

  1. Oxide stoichiometry-controlled TaOx-based resistive switching behaviors

    Science.gov (United States)

    Baek, Gwang Ho; Lee, Ah Rahm; Kim, Tae Yoon; Im, Hyun Sik; Hong, Jin Pyo

    2016-10-01

    We examine the influence of variable oxygen concentration in TaOx active layers on the forming process and bipolar resistive switching (BRS) features of TaOx-based resistive switching cells. TaOx active layers prepared using various rf sputtering powers were systematically analyzed to identify the relation between initial compositions and BRS behavior. Proper control of oxygen vacancy concentration was clearly identified as a basic factor in ensuring typical BRS features without affecting the structural properties. We describe the possible origins of both conduction and switching based on the variation of oxygen concentrations initially provided by the growth conditions.

  2. Structural studies of the metal-rich region in the ternary Ta-Nb-S system

    Energy Technology Data Exchange (ETDEWEB)

    Yao, Xiaoqiang.

    1991-10-07

    Six new solid solution type compounds have been prepared using high temperature techniques and characterized by means of single crystal x-ray techniques during a study of the metal-rich region of the ternary Ta-Nb-S system. The structures of Nb{sub x}Ta{sub 11-x}S{sub 4} are reminiscent of niobium-rich sulfides, rather than of tantalum-rich sulfides. The coordinations of sulfur are capped trigonal prismatic while the metal coordinations are capped distorted cubic prismatic for Nb{sub x}Ta{sub 11-x}S{sub 4}, and capped distorted cubic prismatic and pentagonal prismatic for Nb{sub 12-x}Ta{sub x}S{sub 4}. The structures of Nb{sub x}Ta{sub 5-x}S{sub 2} contain homoatomic layers sequenced S-M3-M2-M1-M2-M3-S (M is mixed Nb, Ta) generating six-layer sheets, respectively. Weak S-S interactions at 3.26 and 3.19{Angstrom} between sheets contrast with the M-M binding within and between the sheets in these two novel layered compounds. The former are presumably responsible for the observed graphitic slippage of the samples. Nb{sub 21-x}Ta{sub x}S{sub 8} and Nb{sub x}Ta{sub 2-x}S are isostructural with Nb{sub 21}S{sub 8} and Ta{sub 2}S, respectively. Extended Hueckel band calculations were carried out for two layered compounds, Nb{sub x}Ta{sub 5-x}S{sub 2} (x {approx} 1.72) and Nb{sub x}ta{sub 2-x}S (x {approx} 0.95). Based upon band calculations metallic properties can be expected for these two layered compounds. The relative preference of the metal sites for the two metal elements (Ta, Nb) in two layered compounds is explained by the results of the band calculations. 17 figs., 31 tabs., 80 refs.

  3. Water Solubility of Plutonium and Uranium Compounds and Residues at TA-55

    Energy Technology Data Exchange (ETDEWEB)

    Reilly, Sean Douglas [Los Alamos National Lab. (LANL), Los Alamos, NM (United States; Smith, Paul Herrick [Los Alamos National Lab. (LANL), Los Alamos, NM (United States; Jarvinen, Gordon D. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States; Prochnow, David Adrian [Los Alamos National Lab. (LANL), Los Alamos, NM (United States; Schulte, Louis D. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States; DeBurgomaster, Paul Christopher [Los Alamos National Lab. (LANL), Los Alamos, NM (United States; Fife, Keith William [Los Alamos National Lab. (LANL), Los Alamos, NM (United States; Rubin, Jim [Los Alamos National Lab. (LANL), Los Alamos, NM (United States; Worl, Laura Ann [Los Alamos National Lab. (LANL), Los Alamos, NM (United States

    2016-06-13

    Understanding the water solubility of plutonium and uranium compounds and residues at TA-55 is necessary to provide a technical basis for appropriate criticality safety, safety basis and accountability controls. Individual compound solubility was determined using published solubility data and solution thermodynamic modeling. Residue solubility was estimated using a combination of published technical reports and process knowledge of constituent compounds. The scope of materials considered includes all compounds and residues at TA-55 as of March 2016 that contain Pu-239 or U-235 where any single item in the facility has more than 500 g of nuclear material. This analysis indicates that the following materials are not appreciably soluble in water: plutonium dioxide (IDC=C21), plutonium phosphate (IDC=C66), plutonium tetrafluoride (IDC=C80), plutonium filter residue (IDC=R26), plutonium hydroxide precipitate (IDC=R41), plutonium DOR salt (IDC=R42), plutonium incinerator ash (IDC=R47), uranium carbide (IDC=C13), uranium dioxide (IDC=C21), U3O8 (IDC=C88), and uranium filter residue (IDC=R26). This analysis also indicates that the following materials are soluble in water: plutonium chloride (IDC=C19) and uranium nitrate (IDC=C52). Equilibrium calculations suggest that PuOCl is water soluble under certain conditions, but some plutonium processing reports indicate that it is insoluble when present in electrorefining residues (R65). Plutonium molten salt extraction residues (IDC=R83) contain significant quantities of PuCl3, and are expected to be soluble in water. The solubility of the following plutonium residues is indeterminate due to conflicting reports, insufficient process knowledge or process-dependent composition: calcium salt (IDC=R09), electrorefining salt (IDC=R65), salt (IDC=R71), silica (IDC=R73) and sweepings/screenings (IDC=R78). Solution thermodynamic modeling also indicates that fire suppression water buffered with a

  4. Molecular evolution of the rice blast resistance gene Pi-ta in invasive weedy rice in the USA.

    Directory of Open Access Journals (Sweden)

    Seonghee Lee

    Full Text Available The Pi-ta gene in rice has been effectively used to control rice blast disease caused by Magnaporthe oryzae worldwide. Despite a number of studies that reported the Pi-ta gene in domesticated rice and wild species, little is known about how the Pi-ta gene has evolved in US weedy rice, a major weed of rice. To investigate the genome organization of the Pi-ta gene in weedy rice and its relationship to gene flow between cultivated and weedy rice in the US, we analyzed nucleotide sequence variation at the Pi-ta gene and its surrounding 2 Mb region in 156 weedy, domesticated and wild rice relatives. We found that the region at and around the Pi-ta gene shows very low genetic diversity in US weedy rice. The patterns of molecular diversity in weeds are more similar to cultivated rice (indica and aus, which have never been cultivated in the US, rather than the wild rice species, Oryza rufipogon. In addition, the resistant Pi-ta allele (Pi-ta found in the majority of US weedy rice belongs to the weedy group strawhull awnless (SH, suggesting a single source of origin for Pi-ta. Weeds with Pi-ta were resistant to two M. oryzae races, IC17 and IB49, except for three accessions, suggesting that component(s required for the Pi-ta mediated resistance may be missing in these accessions. Signatures of flanking sequences of the Pi-ta gene and SSR markers on chromosome 12 suggest that the susceptible pi-ta allele (pi-ta, not Pi-ta, has been introgressed from cultivated to weedy rice by out-crossing.

  5. Molecular evolution of the rice blast resistance gene Pi-ta in invasive weedy rice in the USA.

    Science.gov (United States)

    Lee, Seonghee; Jia, Yulin; Jia, Melissa; Gealy, David R; Olsen, Kenneth M; Caicedo, Ana L

    2011-01-01

    The Pi-ta gene in rice has been effectively used to control rice blast disease caused by Magnaporthe oryzae worldwide. Despite a number of studies that reported the Pi-ta gene in domesticated rice and wild species, little is known about how the Pi-ta gene has evolved in US weedy rice, a major weed of rice. To investigate the genome organization of the Pi-ta gene in weedy rice and its relationship to gene flow between cultivated and weedy rice in the US, we analyzed nucleotide sequence variation at the Pi-ta gene and its surrounding 2 Mb region in 156 weedy, domesticated and wild rice relatives. We found that the region at and around the Pi-ta gene shows very low genetic diversity in US weedy rice. The patterns of molecular diversity in weeds are more similar to cultivated rice (indica and aus), which have never been cultivated in the US, rather than the wild rice species, Oryza rufipogon. In addition, the resistant Pi-ta allele (Pi-ta) found in the majority of US weedy rice belongs to the weedy group strawhull awnless (SH), suggesting a single source of origin for Pi-ta. Weeds with Pi-ta were resistant to two M. oryzae races, IC17 and IB49, except for three accessions, suggesting that component(s) required for the Pi-ta mediated resistance may be missing in these accessions. Signatures of flanking sequences of the Pi-ta gene and SSR markers on chromosome 12 suggest that the susceptible pi-ta allele (pi-ta), not Pi-ta, has been introgressed from cultivated to weedy rice by out-crossing.

  6. A Remote Sensing Method for Estimating Surface Air Temperature and Surface Vapor Pressure on a Regional Scale

    Directory of Open Access Journals (Sweden)

    Renhua Zhang

    2015-05-01

    Full Text Available This paper presents a method of estimating regional distributions of surface air temperature (Ta and surface vapor pressure (ea, which uses remotely-sensed data and meteorological data as its inputs. The method takes into account the effects of both local driving force and horizontal advection on Ta and ea. Good correlation coefficients (R2 and root mean square error (RMSE between the measurements of Ta/ea at weather stations and Ta/ea estimates were obtained; with R2 of 0.77, 0.82 and 0.80 and RMSE of 0.42K, 0.35K and 0.20K for Ta and with R2 of 0.85, 0.88, 0.88 and RMSE of 0.24hpa, 0.35hpa and 0.16hpa for ea, respectively, for the three-day results. This result is much better than that estimated from the inverse distance weighted method (IDW. The performance of Ta/ea estimates at Dongping Lake illustrated that the method proposed in the paper also has good accuracy for a heterogeneous surface. The absolute biases of Ta and ea estimates at Dongping Lake from the proposed method are less than 0.5Kand 0.7hpa, respectively, while the absolute biases of them from the IDW method are more than 2K and 3hpa, respectively. Sensitivity analysis suggests that the Ta estimation method presented in the paper is most sensitive to surface temperature and that the ea estimation method is most sensitive to available energy.

  7. Microstructural characterization of Ta-Si alloy as cast; Caracterizacao microestrutural de ligas Ta-Si no estado bruto de fusao

    Energy Technology Data Exchange (ETDEWEB)

    Silva, A.A.A.P. da; Coelho, G.C.; Nunes, C.A.; Suzuki, P.A.; Borges, S.P.T., E-mail: antonioaaps@gmail.co [Universidade de Sao Paulo (EEL/USP), Lorena, SP (Brazil). Escola de Engenharia; Faria, M.I.S.T. [Centro Universitario de Volta Redonda (UNIFOA), RJ (Brazil)

    2010-07-01

    Recent experimental studies developed in our group involving systems containing transition metals and silicon differed from the phase diagrams actually accepted. The objective of this study is to experimentally re-evaluate the invariant reactions involving liquid phase of the binary Ta-Si. Samples with different compositions were melted in arc furnace with non-consumable tungsten electrode in the copper crucible cooled water under argon atmosphere and titanium getter, using materials of high purity (minimum purity of 99.5% Ta and 99.999% Si). The samples were melted four times to ensure the microstructural and compositional homogeneity. The microstructures of the samples as cast were characterized by scanning electron microscopy (SEM/EDS) and X-ray diffraction (XRD). The results of this analysis led to a proposal for the phase diagram of Ta-Si slightly different than the diagram currently accepted. (author)

  8. Ground-based tests of JEM-EUSO components at the Telescope Array site, "EUSO-TA"

    Science.gov (United States)

    Adams, J. H.; Ahmad, S.; Albert, J.-N.; Allard, D.; Anchordoqui, L.; Andreev, V.; Anzalone, A.; Arai, Y.; Asano, K.; Ave Pernas, M.; Baragatti, P.; Barrillon, P.; Batsch, T.; Bayer, J.; Bechini, R.; Belenguer, T.; Bellotti, R.; Belov, K.; Berlind, A. A.; Bertaina, M.; Biermann, P. L.; Biktemerova, S.; Blaksley, C.; Blanc, N.; Błȩcki, J.; Blin-Bondil, S.; Blümer, J.; Bobik, P.; Bogomilov, M.; Bonamente, M.; Briggs, M. S.; Briz, S.; Bruno, A.; Cafagna, F.; Campana, D.; Capdevielle, J.-N.; Caruso, R.; Casolino, M.; Cassardo, C.; Castellinic, G.; Catalano, C.; Catalano, G.; Cellino, A.; Chikawa, M.; Christl, M. J.; Cline, D.; Connaughton, V.; Conti, L.; Cordero, G.; Crawford, H. J.; Cremonini, R.; Csorna, S.; Dagoret-Campagne, S.; de Castro, A. J.; De Donato, C.; de la Taille, C.; De Santis, C.; del Peral, L.; Dell'Oro, A.; De Simone, N.; Di Martino, M.; Distratis, G.; Dulucq, F.; Dupieux, M.; Ebersoldt, A.; Ebisuzaki, T.; Engel, R.; Falk, S.; Fang, K.; Fenu, F.; Fernández-Gómez, I.; Ferrarese, S.; Finco, D.; Flamini, M.; Fornaro, C.; Franceschi, A.; Fujimoto, J.; Fukushima, M.; Galeotti, P.; Garipov, G.; Geary, J.; Gelmini, G.; Giraudo, G.; Gonchar, M.; González Alvarado, C.; Gorodetzky, P.; Guarino, F.; Guzmán, A.; Hachisu, Y.; Harlov, B.; Haungs, A.; Hernández Carretero, J.; Higashide, K.; Ikeda, D.; Ikeda, H.; Inoue, N.; Inoue, S.; Insolia, A.; Isgrò, F.; Itow, Y.; Joven, E.; Judd, E. G.; Jung, A.; Kajino, F.; Kajino, T.; Kaneko, I.; Karadzhov, Y.; Karczmarczyk, J.; Karus, M.; Katahira, K.; Kawai, K.; Kawasaki, Y.; Keilhauer, B.; Khrenov, B. A.; Kim, J.-S.; Kim, S.-W.; Kim, S.-W.; Kleifges, M.; Klimov, P. A.; Kolev, D.; Kreykenbohm, I.; Kudela, K.; Kurihara, Y.; Kusenko, A.; Kuznetsov, E.; Lacombe, M.; Lachaud, C.; Lee, J.; Licandro, J.; Lim, H.; López, F.; Maccarone, M. C.; Mannheim, K.; Maravilla, D.; Marcelli, L.; Marini, A.; Martinez, O.; Masciantonio, G.; Mase, K.; Matev, R.; Medina-Tanco, G.; Mernik, T.; Miyamoto, H.; Miyazaki, Y.; Mizumoto, Y.; Modestino, G.; Monaco, A.; Monnier-Ragaigne, D.; Morales de los Ríos, J. A.; Moretto, C.; Morozenko, V. S.; Mot, B.; Murakami, T.; Murakami, M. Nagano; Nagata, M.; Nagataki, S.; Nakamura, T.; Napolitano, T.; Naumov, D.; Nava, R.; Neronov, A.; Nomoto, K.; Nonaka, T.; Ogawa, T.; Ogio, S.; Ohmori, H.; Olinto, A. V.; Orleański, P.; Osteria, G.; Panasyuk, M. I.; Parizot, E.; Park, I. H.; Park, H. W.; Pastircak, B.; Patzak, T.; Paul, T.; Pennypacker, C.; Perez Cano, S.; Peter, T.; Picozza, P.; Pierog, T.; Piotrowski, L. W.; Piraino, S.; Plebaniak, Z.; Pollini, A.; Prat, P.; Prévôt, G.; Prieto, H.; Putis, M.; Reardon, P.; Reyes, M.; Ricci, M.; Rodríguez, I.; Rodríguez Frías, M. D.; Ronga, F.; Roth, M.; Rothkaehl, H.; Roudil, G.; Rusinov, I.; Rybczyński, M.; Sabau, M. D.; Sáez-Cano, G.; Sagawa, H.; Saito, A.; Sakaki, N.; Sakata, M.; Salazar, H.; Sánchez, S.; Santangelo, A.; Santiago Crúz, L.; Sanz Palomino, M.; Saprykin, O.; Sarazin, F.; Sato, H.; Sato, M.; Schanz, T.; Schieler, H.; Scotti, V.; Segreto, A.; Selmane, S.; Semikoz, D.; Serra, M.; Sharakin, S.; Shibata, T.; Shimizu, H. M.; Shinozaki, K.; Shirahama, T.; Siemieniec-Oziȩbło, G.; Silva López, H. H.; Sledd, J.; Słomińska, K.; Sobey, A.; Sugiyama, T.; Supanitsky, D.; Suzuki, M.; Szabelska, B.; Szabelski, J.; Tajima, F.; Tajima, N.; Tajima, T.; Takahashi, Y.; Takami, H.; Takeda, M.; Takizawa, Y.; Tenzer, C.; Tibolla, O.; Tkachev, L.; Tokuno, H.; Tomida, T.; Tone, N.; Toscano, S.; Trillaud, F.; Tsenov, R.; Tsunesada, Y.; Tsuno, K.; Tymieniecka, T.; Uchihori, Y.; Unger, M.; Vaduvescu, O.; Valdés-Galicia, J. F.; Vallania, P.; Valore, L.; Vankova, G.; Vigorito, C.; Villaseñor, L.; von Ballmoos, P.; Wada, S.; Watanabe, J.; Watanabe, S.; Watts, J.; Weber, M.; Weiler, T. J.; Wibig, T.; Wiencke, L.; Wille, M.; Wilms, J.; Włodarczyk, Z.; Yamamoto, T.; Yamamoto, Y.; Yang, J.; Yano, H.; Yashin, I. V.; Yonetoku, D.; Yoshida, K.; Yoshida, S.; Young, R.; Zotov, M. Yu.; Zuccaro Marchi, A.

    2015-11-01

    We are conducting tests of optical and electronics components of JEMEUSO at the Telescope Array site in Utah with a ground-based "EUSO-TA" detector. The tests will include an engineering validation of the detector, cross-calibration of EUSO-TA with the TA fluorescence detector and observations of air shower events. Also, the proximity of the TA's Electron Light Source will allow for convenient use of this calibration device. In this paper, we report initial results obtained with the EUSO-TA telescope.

  9. Charge modulation and structural transformation in TaTe2 studied by scanning tunneling microscopy/spectroscopy

    Science.gov (United States)

    Feng, Jiagui; Tan, Andrew; Wagner, Sean; Liu, Jinyu; Mao, Zhiqiang; Ke, Xianglin; Zhang, Pengpeng

    2016-07-01

    We show that the (3 × 1) stripe structure observed in TaTe2 at room temperature arises from the formation of Ta4+-Ta4+ dimer chains along with a separate chain of Ta3+. More importantly, we reveal an intriguing lattice distortion and charge modulation at low temperature, which suggests an interplay and competition between the triple-axis (3 × 3) charge density wave-like modulation and the single-axis (3 × 1) stripe configuration. This work highlights the importance of TaTe2 as an alternative platform with rich structural and electrical phases to explore charge-lattice coupling.

  10. Technology Estimating 2: A Process to Determine the Cost and Schedule of Space Technology Research and Development

    Science.gov (United States)

    Cole, Stuart K.; Wallace, Jon; Schaffer, Mark; May, M. Scott; Greenberg, Marc W.

    2014-01-01

    As a leader in space technology research and development, NASA is continuing in the development of the Technology Estimating process, initiated in 2012, for estimating the cost and schedule of low maturity technology research and development, where the Technology Readiness Level is less than TRL 6. NASA' s Technology Roadmap areas consist of 14 technology areas. The focus of this continuing Technology Estimating effort included four Technology Areas (TA): TA3 Space Power and Energy Storage, TA4 Robotics, TA8 Instruments, and TA12 Materials, to confine the research to the most abundant data pool. This research report continues the development of technology estimating efforts completed during 2013-2014, and addresses the refinement of parameters selected and recommended for use in the estimating process, where the parameters developed are applicable to Cost Estimating Relationships (CERs) used in the parametric cost estimating analysis. This research addresses the architecture for administration of the Technology Cost and Scheduling Estimating tool, the parameters suggested for computer software adjunct to any technology area, and the identification of gaps in the Technology Estimating process.

  11. Influences of Pr and Ta doping concentration on the characteristic features of FTO thin film deposited by spray pyrolysis

    Science.gov (United States)

    Güven, Turgut; Adem, Koçyiğit; Erdal, Sönmez

    2015-10-01

    The Pr and Ta separately doped FTO (10 at.% F incorporated SnO2) films are fabricated via spray pyrolysis. The microstructural, topographic, optical, and electrical features of fluorine-doped TO (FTO) films are investigated as functions of Pr and Ta dopant concentrations. The x-ray diffraction (XRD) measurements reveal that all deposited films show polycrystalline tin oxide crystal property. FTO film has (200) preferential orientation, but this orientation changes to (211) direction with Pr and Ta doping ratio increasing. Atomic force microscopy (AFM) and scanning electron microscopy (SEM) analyses show that all films have uniform and homogenous nanoparticle distributions. Furthermore, morphologies of the films depend on the ratio between Pr and Ta dopants. From ultraviolet-visible (UV-Vis) spectrophotometer measurements, it is shown that the transmittance value of FTO film decreases with Pr and Ta doping elements increasing. The band gap value of FTO film increases only at 1 at.% Ta doping level, it drops off with Pr and Ta doping ratio increasing at other doped FTO films. The electrical measurements indicate that the sheet resistance value of FTO film initially decreases with Pr and Ta doping ratio decreasing and then it increases with Pr and Ta doping ratio increasing. The highest value of figure of merit is obtained for 1 at.% Ta- and Pr-doped FTO film. These results suggest that Pr- and Ta-doped FTO films may be appealing candidates for TCO applications.

  12. Effect of nitrogen content on the degradation mechanisms of thin Ta-Si-N diffusion barriers for Cu metallization

    Energy Technology Data Exchange (ETDEWEB)

    Huebner, R. [Leibniz Institute for Solid State and Materials Research Dresden, Helmholtzstrasse 20, D-01069 Dresden (Germany)]. E-mail: rhuebner@uamail.albany.edu; Hecker, M. [Leibniz Institute for Solid State and Materials Research Dresden, Helmholtzstrasse 20, D-01069 Dresden (Germany); Mattern, N. [Leibniz Institute for Solid State and Materials Research Dresden, Helmholtzstrasse 20, D-01069 Dresden (Germany); Hoffmann, V. [Leibniz Institute for Solid State and Materials Research Dresden, Helmholtzstrasse 20, D-01069 Dresden (Germany); Wetzig, K. [Leibniz Institute for Solid State and Materials Research Dresden, Helmholtzstrasse 20, D-01069 Dresden (Germany); Heuer, H. [Dresden University of Technology, Semiconductor and Microsystems Technology Laboratory, D-01062 Dresden (Germany); Wenzel, Ch. [Dresden University of Technology, Semiconductor and Microsystems Technology Laboratory, D-01062 Dresden (Germany); Engelmann, H.-J. [AMD Saxony LLC and Co. KG, Materials Analysis Department, D-01330 Dresden (Germany); Gehre, D. [AMD Saxony LLC and Co. KG, Materials Analysis Department, D-01330 Dresden (Germany); Zschech, E. [AMD Saxony LLC and Co. KG, Materials Analysis Department, D-01330 Dresden (Germany)

    2006-04-03

    The effect of the nitrogen content on the thermal stability and degradation mechanisms of Ta-Si-N diffusion barriers was studied using methods that prove Cu interdiffusion. On the one hand, glancing angle X-ray diffraction was applied to detect Cu{sub 3}Si formation after annealing of Cu/Ta-Si-N/Si layer stacks. On the other hand, a combined secondary ion mass spectroscopy and transmission electron microscopy analysis of Ta-Si-N/Cu/Ta-Si-N/SiO{sub 2}/Si samples was performed. For a detailed investigation of the microstructure evolution, the crystallization behavior of both Cu-capped and uncapped Ta-Si-N/Si samples was analyzed using X-ray diffraction. In the case of an uncapped Ta{sub 73}Si{sub 27} film, Si interdiffusion from the substrate precedes the layer crystallization. The substrate influence on the crystallization process decreases with increasing N content x {sub N} of the Ta-Si-N layer. Using Cu/Ta-Si-N/Si samples, a critical temperature for Cu silicide formation was determined. This temperature increases with increasing N content of the Ta-Si-N barrier. In the case of Ta-Si-N films with x {sub N} > 25 at.%, Cu interdiffusion into the substrate occurs before a significant barrier crystallization is observed. For Ta-Si-N layers with x {sub N} {<=} 25 at.%, no indications for Cu diffusion before crystalline phase formation were detected.

  13. Influences of Pr and Ta doping concentration on the characteristic features of FTO thin film deposited by spray pyrolysis

    Institute of Scientific and Technical Information of China (English)

    G ¨uven Turgut; Adem Koc¸ yi˘git; Erdal S ¨onmez

    2015-01-01

    The Pr and Ta separately doped FTO (10 at.%F incorporated SnO2) films are fabricated via spray pyrolysis. The mi-crostructural, topographic, optical, and electrical features of fl uorine-doped TO (FTO) films are investigated as functions of Pr and Ta dopant concentrations. The x-ray diffraction (XRD) measurements reveal that all deposited films show polycrys-talline tin oxide crystal property. FTO film has (200) preferential orientation, but this orientation changes to (211) direction with Pr and Ta doping ratio increasing. Atomic force microscopy (AFM) and scanning electron microscopy (SEM) anal-yses show that all films have uniform and homogenous nanoparticle distributions. Furthermore, morphologies of the films depend on the ratio between Pr and Ta dopants. From ultraviolet-visible (UV-Vis) spectrophotometer measurements, it is shown that the transmittance value of FTO film decreases with Pr and Ta doping elements increasing. The band gap value of FTO film increases only at 1 at.%Ta doping level, it drops off with Pr and Ta doping ratio increasing at other doped FTO films. The electrical measurements indicate that the sheet resistance value of FTO film initially decreases with Pr and Ta doping ratio decreasing and then it increases with Pr and Ta doping ratio increasing. The highest value of figure of merit is obtained for 1 at.%Ta-and Pr-doped FTO film. These results suggest that Pr-and Ta-doped FTO films may be appealing candidates for TCO applications.

  14. Mechanical Properties of Nb25Mo25Ta25W25 and V20Nb20Mo20Ta20W20 Refractory High Entropy Alloys (Postprint)

    Science.gov (United States)

    2011-05-01

    temper ature from 548 MPa at 1000 C to 405 MPa at 1600 C (Table 2).ublic release; distribution unlimited. Table 4 Composition (in wt.%) of Inconel 718 ...values of the refractory HEAs are much higher than those of Haynes 230 at all studied temperatures and higher than those of Inconel 718 at...than twice (for the Nb25Mo25 Ta25W25 alloy) or four times (for the V20Nb20Mo20Ta20W20 alloy) higher than for Inconel 718 or Haynes 230 at 1000 C. The

  15. Mechanical properties and biocompatibility in alloy Ti-Ta system containing oxygen; Propriedades mecanicas e biocompatibilidades em ligas do sistema Ti-Ta contendo oxigenio

    Energy Technology Data Exchange (ETDEWEB)

    Ruiz, S.L.M.; Grandini, C.R., E-mail: samlea@fc.unesp.b [Universidade Estadual Paulista (UNESP), Bauru, SP (Brazil). Lab. de Anelasticidade e Biomateriais; Claro, A.P.R.A. [Universidade Estadual Paulista Julio de Mesquisa Filho (DMT/UNESP), Guaratingueta, SP (Brazil). Fac. de Engenharia. Dept. de Materiais e Tecnologia

    2010-07-01

    Due to the excellent properties such as corrosion resistance, good mechanical strength/density, good performance at high temperatures, Ti is very useful in the chemical industry and aerospace. Currently, their use has expanded to the field of biomaterials, due to its excellent biocompatibility and reduced elasticity modulus, favouring the production of orthopaedic and dental prostheses. Promising alloys are the Ti-Ta system and researches have been directed to describe and understand the behavior of this system. In this paper, samples of Ti-Ta alloys containing 8 and 16% (wt%) containing interstitial oxygen were prepared and characterized by density, xray diffraction, hardness, elasticity modulus measurements and in vitro cytotoxicity tests. (author)

  16. Bixbyite-type phases in the system Ta-Zr-O-N

    Energy Technology Data Exchange (ETDEWEB)

    Luedtke, Tobias; Orthmann, Steven; Lerch, Martin [Technische Univ. Berlin (Germany). Inst. fuer Chemie

    2017-06-01

    Phase-pure tantalum/zirconium oxide nitrides and nitrides were synthesized by the ammonolysis of amorphous oxide precursors. The nitrogen-rich oxide nitrides with variable anion composition and the nitride TaZrN3 crystallize in the cubic bixbyite-type structure (space group Ia3). The nitrogen content of these compounds has a significant influence on the cell parameters, the atomic positions, and the optical band gap. The results extend the already well-studied Ta-Zr-O-N system by new oxide nitrides in addition to the already known baddeleyite- and anosovite-type phases. TaZrN{sub 3} can be considered as a thermodynamically stable ternary variant of metastable Ta{sub 2}N{sub 3}.

  17. CRED REA Coral Population Parameters at Ta'u, American Samoa, 2004

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Belt transects along 2 consecutively-placed, 25m transect lines were surveyed as part of Rapid Ecological Assessments conducted at 9 sites at Ta'u in American Samoa...

  18. CRED REA Coral Population Parameters at Ta'u Island, American Samoa in 2008

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Belt transects along 2 consecutively-placed, 25m transect lines were surveyed as part of Rapid Ecological Assessments conducted at 9 sites around Ta'u Island in...

  19. Stormwater Pollution Prevention Plan TA-60 Roads and Grounds Facility and Associated Sigma Mesa Staging Area

    Energy Technology Data Exchange (ETDEWEB)

    Sandoval, Leonard Frank [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-02-01

    This Stormwater Pollution Prevention Plan (SWPPP) is applicable to operations at the Technical Area -60 (TA-60) Roads and Grounds Facility and Associated Sigma Mesa Staging Area off Eniwetok Drive, in Los Alamos County, New Mexico.

  20. Stormwater Pollution Prevention Plan TA-60 Asphalt Batch Plant Revision 2: January 2017

    Energy Technology Data Exchange (ETDEWEB)

    Sandoval, Leonard Frank [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-02-01

    The Stormwater Pollution Prevention Team (PPT) is applicable to operations at the Technical Area (TA)- 60 Asphalt Batch Plant (ABP) located on Eniwetok Drive/Sigma Mesa, in Los Alamos County, New Mexico at Los Alamos National Laboratory (LANL).

  1. Fast ultradense GdTa1-xNbxO4 scintillator crystals

    Science.gov (United States)

    Voloshyna, Olesia; Gerasymov, Iaroslav; Sidletskiy, Oleg; Kurtsev, Daniil; Gorbacheva, Tatyana; Hubenko, Kateryna; Boiaryntseva, Ianina; Ivanov, Alexey; Spassky, Dmitry; Omelkov, Sergey; Belsky, Andrei

    2017-04-01

    Single crystals of GdTaO4 and GdTa0.8Nb0.2O4 were grown by the Czochralski technique, and their luminescent and scintillation properties were studied. Both crystals demonstrate fast emission with decay time around 10-8 s. Meanwhile, in GdTaO4 the fast decay is accompanied by a huge build-up with the decay time around 1 μs, while in the mixed crystal the contribution of slow components is negligible. UV- and X-ray excited luminescence, curves of thermostimulated luminescence and absolute light yields of crystals are presented as well. GdTa0.8Nb0.2O4 crystal is shown to be an ultradense (8.37 g/cm3) and fast (shortest component decay time 17 ns) scintillator with a high stopping power.

  2. Microstructure characteristic and formation mechanism of crackfree TaC coating on C/C composite

    Institute of Scientific and Technical Information of China (English)

    LI Guo-dong; XIONG Xiang; HUANG Bai-yun

    2005-01-01

    The microstructure characteristic and formation mechanism of the crackfree and ablation-resistant TaC coating deposited on the C/C composite by Chemical Vapour Deposition(CVD) were investigated, using the reaction system of TaCl5-C3H6-H2-Ar. The results show that the nanosized pore structure formed in the TaC coating interior during CVD process is the main factor to reduce the hardness, elastic modulus, linear expansibility and inner thermal stress. Then crackfree coatings can be prepared and their thermal shock resistance can be enhanced. To obtain the dense and homogeneous matrix surface is necessary for the crackfree and low stress coating. The TaC coating structure that distributes from the dense matrix towards loose coating surface will result in the thick crackfree coating with good thermal shock resistance.

  3. Nanocrystalline [beta]-Ta Coating Enhances the Longevity and Bioactivity of Medical Titanium Alloys

    National Research Council Canada - National Science Library

    Linlin Liu; Jiang Xu; Shuyun Jiang

    2016-01-01

      A [beta]-Ta nanocrystalline coating was engineered onto a Ti-6Al-4V substrate using a double cathode glow discharge technique to improve the corrosion resistance and bioactivity of this biomedical alloy...

  4. Data of evolutionary structure change: 1ELTA-2G4TA [Confc[Archive

    Lifescience Database Archive (English)

    Full Text Available 1ELTA-2G4TA 1ELT 2G4T A A VVGGRVAQPNSWPWQISLQYKSGSSYYHTCGGSLIRQGW...VGGTEAQRNSWPSQISLQYRSGSSWAHTCGGTLIRQNWVMTAAHCVDRELTFRVVVGEHNLNQNDGTEQYVGVQKIVVHPY...E EEEEEEEEEEEE EEEEEEGG HHHHHHHHH 0 1ELT... A 1ELTA

  5. CRED REA Fish Team Stationary Point Count Surveys at Ta'u, American Samoa, 2006

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Stationary Point Counts at 4 stations at each survey site were surveyed as part of Rapid Ecological Assessments (REA) conducted at 9 sites around Ta'u in the...

  6. CRED REA Fish Team Belt Transect Survey at Ta'u, 2004

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Belt transects along 3 consecutively-placed, 25m transect lines were surveyed as part of Rapid Ecological Assessments conducted at 9 sites at Ta'u Islands in...

  7. CRED REA Fish Team Stationary Point Count Surveys at Ta'u, 2004

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Stationary Point Counts at 4 stations at each survey site were surveyed as part of Rapid Ecological Assessments conducted at 9 sites at Ta'u, Island in American...

  8. CRED REA Coral Population Paramaters at Ta'u, American Samoa, 2006

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Belt transects along 1 or 2 consecutively-placed, 25m transect lines were surveyed as part of Rapid Ecological Assessments conducted at 9 sites at Ta'u Island in...

  9. CRED REA Coral Health and Disease Assessment at Ta'u Island, American Samoa in 2008

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Coral health and disease assessments were conducted along 2 consecutively placed 25-m transects, as part of Rapid Ecological Assessments conducted at 9 sites at Ta'u...

  10. CRED REA Fish Team Belt Transect Survey at Ta'u, American Samoa, 2006

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Belt transects along 3 consecutively-placed, 25m transect lines were surveyed as part of Rapid Ecological Assessments conducted at 9 sites at Ta'u in the American...

  11. Evaluation of electric field intensity on atom diffusion of Cu/Ta/Si stacks during annealing

    Energy Technology Data Exchange (ETDEWEB)

    Wang, L. [Jiangsu University of Science and Technology, Key Laboratory of Advanced Welding Technology of Jiangsu Province, Zhenjiang (China); Nanjing University, Stomatology Department, Nanjing General Hospital of Nanjing Command, Medical School, Nanjing (China); Jin, L. [Nanjing University, Stomatology Department, Nanjing General Hospital of Nanjing Command, Medical School, Nanjing (China); Yu, L.H.; Dong, S.T.; Chen, J.; Xu, J.H. [Jiangsu University of Science and Technology, Key Laboratory of Advanced Welding Technology of Jiangsu Province, Zhenjiang (China)

    2016-01-15

    Cu/Ta/Si stacks were prepared and, subsequently, annealed at 650 C with different electric field intensity (0-4.0 kV/cm). The effect of electric field intensity on atomic diffusion was determined from cross-sectional TEM micrographs of Cu/Ta/Si stacks. The atomic diffusion as well as the growth of amorphous layer at Ta/Si interface tended to enhance with the increased electric field intensity at 650 C. The growth of amorphous layer obeyed a logarithmic law. The reduction in diffusion activation energy Q by increased electric field intensity will accelerate the atom diffusion, leading to significant barrier failure of Cu/Ta/Si stacks. (orig.)

  12. Queer paradox/paradoxical queer: Anne Garréta's Pas un jour (2002).

    Science.gov (United States)

    Cairns, Lucille

    2007-01-01

    This paper shows how Anne Garréta's Pas un jour (2002) is a decidedly queer text, in both the new and the old sense of that contested epithet. I examine three interrelated concerns central to Pas un jour. First, I analyze Garréta's mediation of desire in general: her own experiences of it; modalities thereof which subvert more 'normative' models of lesbianism; and her convergences with other gay, but male writers and theorists of desire such as Guy Hocquenghem, Gilles Deleuze and Michel Foucault. Second, I interrogate Garréta's dichotomy between desire and friendship, and adumbrate contrasts with Foucauldian theory. Finally, I scrutinize the meaning and value attributed to the particular body of desire with which Garréta is most commonly associated-homosexuality- and their links with those of a contemporary gay male writer, Dominique Fernandez.

  13. TA-EUSO - fluorescence measurement with a prototype JEM-EUSO telescope

    Energy Technology Data Exchange (ETDEWEB)

    Sakaki, Naoto; Falk, Stefanie; Haungs, Andreas; Karus, Michael [Karlsruher Institut fuer Technologie (KIT), Karlsruhe (Germany). Inst. fuer Kernphysik (IKP); Bluemer, Johannes [Karlsruher Institut fuer Technologie (KIT), Karlsruhe (Germany). Inst. fuer Kernphysik (IKP); Karlsruher Institut fuer Technologie (KIT), Karlsruhe (Germany). Inst. fuer Experimentelle Kernphysik; Ebersoldt, Andreas [Institut fuer Prozessdatenverarbeitung und Elektronik (IPE) - Karlsruher Institut fuer Technologie (KIT), Karlsruhe (Germany); Huber, Thomas [Karlsruher Institut fuer Technologie (KIT), Karlsruhe (Germany). Inst. fuer Experimentelle Kernphysik; Collaboration: JEM-EUSO-Collaboration

    2013-07-01

    In order to discover the sources of ultra high energy cosmic rays (UHECR's), Extreme Universe Space Observatory on-board Japan Experiment Module (JEM-EUSO) will observe fluorescence and Cherenkov light from extensive air showers (EASs) induced by UHECRs from the International Space Station with a huge acceptance from 2017. As an important step to realize JEM-EUSO, a prototype telescope, TA-EUSO, will be deployed in early 2013 at the Telescope Array Experiment (TA) site in Utah, U.S.A. to observe ultra-violet light from EASs, LIDAR and the electron light source (ELS). The TA-EUSO telescope consists of two Fresnel lenses of 1m x 1m size each and a Photo-Detector Module (PDM) with 2304 channels at the focal surface which will be used for JEM-EUSO as well. The plan and the present status of the TA-EUSO experiment are reported.

  14. Eesti pronoomenid. I : ühiskeele see, too ja tema/ta / Renate Pajusalu

    Index Scriptorium Estoniae

    Pajusalu, Renate, 1963-

    1997-01-01

    Kolmanda isiku asesõnade ta ja tema ning demonstratiivpronoomenite see ja too kasutamise kontekstist. Ka üldisest deiktoloogiast ehk deiksise mõistest. Järgneb: Keel ja Kirjandus, 1997, nr. 2, lk. 106-115

  15. Barroso väitel jaotas ta volinikukohti talendi järgi / Evelun Kaldoja

    Index Scriptorium Estoniae

    Kaldoja, Evelyn, 1980-

    2009-01-01

    Euroopa Komisjoni presidendi José Manuel Barroso sõnul ei jagatud volinikukohti mitte riikide, vaid oma valikul lähtus ta inimestest ja nende andest. Nimekiri: Järgmise Euroopa Komisjoni volinike kandidaadid. Fotod

  16. Evolution of planetary cores and the Earth-Moon system from Nb/Ta systematics.

    Science.gov (United States)

    Münker, Carsten; Pfänder, Jörg A; Weyer, Stefan; Büchl, Anette; Kleine, Thorsten; Mezger, Klaus

    2003-07-04

    It has been assumed that Nb and Ta are not fractionated during differentiation processes on terrestrial planets and that both elements are lithophile. High-precision measurements of Nb/Ta and Zr/Hf reveal that Nb is moderately siderophile at high pressures. Nb/Ta values in the bulk silicate Earth (14.0 +/- 0.3) and the Moon (17.0 +/- 0.8) are below the chondritic ratio of 19.9 +/- 0.6, in contrast to Mars and asteroids. The lunar Nb/Ta constrains the mass fraction of impactor material in the Moon to less than 65%. Moreover, the Moon-forming impact can be linked in time with the final core-mantle equilibration on Earth 4.533 billion years ago.

  17. TaN molecule as a candidate to search for New physics

    CERN Document Server

    Skripnikov, L V; Mosyagin, N S; Titov, A V; Flambaum, V V

    2015-01-01

    TaN molecule is probably the best candidate to search for T,P-violating nuclear magnetic quadrupole moment (MQM), it also looks promissing to search for other T,P-odd effects. We report results of coupled-cluster calculations of T,P-odd effects in TaN produced by the Ta nucleus MQM, electron electric dipole moment (EDM), scalar$-$pseudoscalar nucleus$-$electron interactions, also of the molecule-axis hyperfine structure constant and dipole moment. Nuclear calculations of $^{181}$Ta MQM are performed to express the T,P-odd effect in terms of the strength constants of T,P-odd nuclear forces, proton and neutron EDM, QCD parameter $\\theta$ and quark chromo-EDM.

  18. Large divergence of satellite and Earth system model estimates of global terrestrial CO2 fertilization

    Science.gov (United States)

    Smith, W. Kolby; Reed, Sasha C.; Cleveland, Cory C.; Ballantyne, Ashley P; Anderegg, William R. L.; Wieder, William R.; Liu, Yi Y; Running, Steven W.

    2015-01-01

    Atmospheric mass balance analyses suggest that terrestrial carbon (C) storage is increasing, partially abating the atmospheric [CO2] growth rate, although the continued strength of this important ecosystem service remains uncertain. Some evidence suggests that these increases will persist owing to positive responses of vegetation growth (net primary productivity; NPP) to rising atmospheric [CO2] (that is, ‘CO2 fertilization’). Here, we present a new satellite-derived global terrestrial NPP data set, which shows a significant increase in NPP from 1982 to 2011. However, comparison against Earth system model (ESM) NPP estimates reveals a significant divergence, with satellite-derived increases (2.8 ± 1.50%) less than half of ESM-derived increases (7.6  ±  1.67%) over the 30-year period. By isolating the CO2 fertilization effect in each NPP time series and comparing it against a synthesis of available free-air CO2 enrichment data, we provide evidence that much of the discrepancy may be due to an over-sensitivity of ESMs to atmospheric [CO2], potentially reflecting an under-representation of climatic feedbacks and/or a lack of representation of nutrient constraints. Our understanding of CO2 fertilization effects on NPP needs rapid improvement to enable more accurate projections of future C cycle–climate feedbacks; we contend that better integration of modelling, satellite and experimental approaches offers a promising way forward.

  19. High mobility of the strongly confined hole gas in AgTaO3/SrTiO3

    KAUST Repository

    Nazir, Safdar

    2012-05-18

    A theoretical study of the two-dimensional hole gas at the (AgO)−/(TiO2)0 p-type interface in the AgTaO3/SrTiO3 (001) heterostructure is presented. The Ag 4d states strongly hybridize with the O 2p states and contribute to the hole gas. It is demonstrated that the holes are confined to an ultra thin layer (∼4.9Å) with a considerable carrier density of ∼1014cm−2. We estimate a hole mobility of 18.6 cm2 V−1 s−1, which is high enough to enable device applications.

  20. Trace Code Validation for BWR Spray Cooling Injection and CCFL Condition Based on GÖTA Facility Experiments

    Directory of Open Access Journals (Sweden)

    Stefano Racca

    2012-01-01

    Full Text Available Best estimate codes have been used in the past thirty years for the design, licensing, and safety of NPP. Nevertheless, large efforts are necessary for the qualification and the assessment of such codes. The aim of this work is to study the main phenomena involved in the emergency spray cooling injection in a Swedish-designed BWR. For this purpose, data from the Swedish separate effect test facility GÖTA have been simulated using TRACE version 5.0 Patch 2. Furthermore, uncertainty calculations have been performed with the propagation of input errors method, and the identification of the input parameters that mostly influence the peak cladding temperature has been performed.

  1. Magnetic properties of ultrathin Ni81Fe19 films with Ta and Ru capping layers.

    Science.gov (United States)

    Kezilebieke, S; Ali, M; Shadeke, B; Gunnella, R

    2013-11-27

    Magnetic properties of Ni81Fe19 (permalloy) ultrathin films with Ru and Ta capping layers (CLs) were investigated for applications to magnetic random access memory units (MRAM). The sample structure, which simulated an MRAM free layer, is Si- sub./SiO2/Ni81Fe19/Ru(Ta). The Ni81Fe19 thin films less than 3 nm thick with Ru CL show low coercive fields compared with the Ta capping layer. Both systems showed loss of momentum equivalent to magnetically dead layers of thickness (δ) ~0.6 nm for Ru cap layer and ~1.4 nm for Ta cap layer, respectively. Moreover, after annealing the thicknesses are slightly increased to an equivalent magnetic dead layer thickness of δ ~0:84 nm and ~1.80 nm for Ru and Ta CL, respectively. Our calculations showed that the presence of only 11% Ta concentration at the interface reduced the Ni momentum to zero, with the Ni–Ta coupling being anti-ferromagnetic; while 50% Ru intermixing at the interface reduced the Ni momentum to zero with the coupling between Ru and Ni being ferromagnetic. To find out more about the intermixing at the interface, the composition and chemical states were characterized by the x-ray photoelectron spectroscopy and peak decomposition technique. The result showed that the peak positions were different from the pure metallic case at the interface region, mainly because of the intermixing between two layers. In conclusion, the Ru capping layer might be important for MRAM use in terms of low coercive field and small δ layer thickness if compared with the Ta capping layer.

  2. Oxygen related recombination defects in Ta{sub 3}N{sub 5} water splitting photoanode

    Energy Technology Data Exchange (ETDEWEB)

    Fu, Gao; Yu, Tao, E-mail: yscfei@nju.edu.cn, E-mail: yutao@nju.edu.cn; Zou, Zhigang [National Laboratory of Solid State Microstructures and Ecomaterials and Renewable Energy Research Center (ERERC) at Department of Physics, Nanjing University, Nanjing 210093 (China); Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093 (China); Jiangsu Key Laboratory for Nano Technology, Nanjing 210093 (China); Yan, Shicheng, E-mail: yscfei@nju.edu.cn, E-mail: yutao@nju.edu.cn [National Laboratory of Solid State Microstructures and Ecomaterials and Renewable Energy Research Center (ERERC) at Department of Physics, Nanjing University, Nanjing 210093 (China); Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093 (China); Jiangsu Key Laboratory for Nano Technology, Nanjing 210093 (China); College of Engineering and Applied Sciences, Nanjing University, Nanjing 210093 (China)

    2015-10-26

    A key route to improving the performance of Ta{sub 3}N{sub 5} photoelectrochemical film devices in solar driving water splitting to hydrogen is to understand the nature of the serious recombination of photo-generated carriers. Here, by using the temperature-dependent photoluminescence (PL) spectrum, we confirmed that for the Ta{sub 3}N{sub 5} films prepared by nitriding Ta{sub 2}O{sub 5} precursor, one PL peak at 561 nm originates from deep-level defects recombination of the oxygen-enriched Ta{sub 3}N{sub 5} phases, and another one at 580 nm can be assigned to band recombination of Ta{sub 3}N{sub 5} itself. Both of the two bulk recombination processes may decrease the photoelectrochemical performance of Ta{sub 3}N{sub 5}. It was difficult to remove the oxygen-enriched impurities in Ta{sub 3}N{sub 5} films by increasing the nitriding temperatures due to their high thermodynamically stability. In addition, a broadening PL peak between 600 and 850 nm resulting from oxygen related surface defects was observed by the low-temperature PL measurement, which may induce the surface recombination of photo-generated carriers and can be removed by increasing the nitridation temperature. Our results provided direct experimental evidence to understand the effect of oxygen-related crystal defects in Ta{sub 3}N{sub 5} films on its photoelectric performance.

  3. Magnetic properties of ultrathin Ni81Fe19 films with Ta and Ru capping layers

    Science.gov (United States)

    Kezilebieke, S.; Ali, M.; Shadeke, B.; Gunnella, R.

    2013-11-01

    Magnetic properties of Ni81Fe19 (permalloy) ultrathin films with Ru and Ta capping layers (CLs) were investigated for applications to magnetic random access memory units (MRAM). The sample structure, which simulated an MRAM free layer, is Si- sub./SiO2/Ni81Fe19/Ru(Ta). The Ni81Fe19 thin films less than 3 nm thick with Ru CL show low coercive fields compared with the Ta capping layer. Both systems showed loss of momentum equivalent to magnetically dead layers of thickness (δ) ˜0.6 nm for Ru cap layer and ˜1.4 nm for Ta cap layer, respectively. Moreover, after annealing the thicknesses are slightly increased to an equivalent magnetic dead layer thickness of δ ˜ 0.84 nm and ˜1.80 nm for Ru and Ta CL, respectively. Our calculations showed that the presence of only 11% Ta concentration at the interface reduced the Ni momentum to zero, with the Ni-Ta coupling being anti-ferromagnetic; while 50% Ru intermixing at the interface reduced the Ni momentum to zero with the coupling between Ru and Ni being ferromagnetic. To find out more about the intermixing at the interface, the composition and chemical states were characterized by the x-ray photoelectron spectroscopy and peak decomposition technique. The result showed that the peak positions were different from the pure metallic case at the interface region, mainly because of the intermixing between two layers. In conclusion, the Ru capping layer might be important for MRAM use in terms of low coercive field and small δ layer thickness if compared with the Ta capping layer.

  4. Preparation of ultrafine LiTaO3 powders by citrate gel method

    Indian Academy of Sciences (India)

    S C Navale; V Samuel; V Ravi

    2005-08-01

    A gel was formed when a aqueous solution of Li(NO3), TaF5 and citric acid in stoichiometric ratio was heated in a water bath. This gel on decomposition at 700°C produced fine crystallites of ternary oxide, LiTaO3 (LT). The phase contents and lattice parameters were studied by powder X-ray diffraction (XRD). Particle size and morphology were studied by transmission electron spectroscopy (TEM).

  5. Microstructure and Elevated Temperature Properties of a Refractory TaNbHfZrTi Alloy

    Science.gov (United States)

    2012-01-24

    alloy was prepared by vacuum arc melting of the equimolar mixtures of the corresponding elements. Titanium, zirconium, and hafnium were in the form of...AND ELEVATED TEMPERATURE PROPERTIES OF A REFRACTORY TaNbHfZrTi ALLOY (POSTPRINT) 5a. CONTRACT NUMBER In-house 5b. GRANT NUMBER 5c. PROGRAM...6260-2. 14. ABSTRACT Compression properties of a refractory multicomponent alloy , Ta20Nb20Hf20Zr20Ti20, were determined in the temperature range

  6. Numerical simulation and experiment of TA2 sheet forming under laser shock

    Institute of Scientific and Technical Information of China (English)

    Li Gao; Jiayang Yu; Yongkang Zhang

    2006-01-01

    @@ The effects of laser energy and different shock spaces and shock times on the TA2 titanium sheet deformation are investigated experimentally and simulated numerically by ABAQUS software. The results indicate that the amount of TA2 sheet deformation increases with the increase of laser energy, varies with shock order and shock path, and is the greatest when the shocks are along the length of sheet and symmetrical.The numerically simulative results are consistent with the experimental data.

  7. Helium and deuterium irradiation effects in W-Ta composites produced by pulse plasma compaction

    Science.gov (United States)

    Dias, M.; Catarino, N.; Nunes, D.; Fortunato, E.; Nogueira, I.; Rosinki, M.; Correia, J. B.; Carvalho, P. A.; Alves, E.

    2017-08-01

    Tungsten-tantalum composites have been envisaged for first-wall components of nuclear fusion reactors; however, changes in their microstructure are expected from severe irradiation with helium and hydrogenic plasma species. In this study, composites were produced from ball milled W powder mixed with 10 at.% Ta fibers through consolidation by pulse plasma compaction. Implantation was carried out at room temperature with He+ (30 keV) or D+ (15 keV) or sequentially with He+ and D+ using ion beams with fluences of 5 × 1021 at/m2. Microstructural changes and deuterium retention in the implanted composites were investigated by scanning electron microscopy, coupled with focused ion beam and energy dispersive X-ray spectroscopy, transmission electron microscopy, X-ray diffraction, Rutherford backscattering spectrometry and nuclear reaction analysis. The composite materials consisted of Ta fibers dispersed in a nanostructured W matrix, with Ta2O5 layers at the interfacial regions. The Ta and Ta2O5 surfaces exhibited blisters after He+ implantation and subsequent D+ implantation worsened the blistering behavior of Ta2O5. Swelling was also pronounced in Ta2O5 where large blisters exhibited an internal nanometer-sized fuzz structure. Transmission electron microscopy revealed an extensive presence of dislocations in the metallic phases after the sequential implantation, while a relatively low density of defects was detected in Ta2O5. This behavior may be partially justified by a shielding effect from the blisters and fuzz structure developed progressively during implantation. The tungsten peaks in the X-ray diffractograms were markedly shifted after He+ implantation, and even more so after the sequential implantation, which is in agreement with the increased D retention inferred from nuclear reaction analysis.

  8. Establishing efficient cobalt based catalytic sites for oxygen evolution on a Ta3N5 photocatalyst

    KAUST Repository

    Nurlaela, Ela

    2015-08-05

    In a photocatalytic suspension system with a powder semiconductor, the interface between the photocatalyst semiconductor and catalyst should be constructed to minimize resistance for charge transfer of excited carriers. This study demonstrates an in-depth understanding of pretreatment effects on the photocatalytic O2 evolution reaction (OER) activity of visible-light-responsive Ta3N5 decorated with CoOx nanoparticles. The CoOx/Ta3N5 sample was synthesized by impregnation followed by sequential heat treat-ments under NH3 flow and air flow at various temperatures. Various characterization techniques, including X-ray diffraction (XRD), X-ray absorption spectroscopy (XAS), scanning transmission electron microscopy (STEM), and X-ray photoelectron spec-troscopy (XPS), were used to clarify the state and role of cobalt. No improvement in photocatalytic activity for OER over the bare Ta3N5 was observed for the as-impregnated CoOx/Ta3N5, likely because of insufficient contact between CoOx and Ta3N5. When the sample was treated in NH3 at high temperature, a substantial improvement in the photocatalytic activity was observed. After NH3 treatment at 700 °C, the Co0-CoOx core-shell agglomerated cobalt structure was identified by XAS and STEM. No metallic cobalt species was evident after the photocatalytic OER, indicating that the metallic cobalt itself is not essential for the reaction. Accordingly, mild oxidation (200 °C) of the NH3-treated CoOx/Ta3N5 sample enhanced photocatalytic OER activity. Oxidation at higher temperatures drastically eliminated the photocatalytic activity, most likely because of unfavorable Ta3N5 oxidation. These results suggest that the intimate contact between cobalt species and Ta3N5 facilitated at high temperature is beneficial to enhancing hole transport and that the cobalt oxide provides electrocatalytic sites for OER.

  9. Determination of phase equilibria in the Ni-Ta-Zr system at 1223 K

    Institute of Scientific and Technical Information of China (English)

    PAN Ximiao; JIN Zhanpeng

    2003-01-01

    The phase equilibrium relations of the ternary Ni-Ta-Zr system at 1223 K were investigated by means of diffusion triple and electron probe microanalysis (EPMA) techniques. Two ternary compounds were found and a series of tie lines and fie triangles have been determined. The maximum solubility of Ta in NiZr2 is about 13.5% (atom fraction). The corresponding tentative isothermal section at this temperature was constructed based on current experimental information.

  10. Structure and physical properties of EuTa2O6 tungsten bronze polymorph

    Science.gov (United States)

    Kolodiazhnyi, T.; Sakurai, H.; Vasylkiv, O.; Borodianska, H.; Forbes, S.; Mozharivskyj, Y.

    2014-08-01

    A tetragonal tungsten bronze (TTB) polymorph of EuTa2O6 was prepared and analyzed. EuTa2O6 crystallizes in the centrosymmetric Pnam space group (with unit cell: a = 12.3693, b = 12.4254, and c = 7.7228 Å) isomorphous with orthorhombic β-SrTa2O6. In contrast to early reports, we see no evidence of deviation from paramagnetic Curie-Weiss behavior among the Eu2+ 4f7spins in EuTa2O6 down to 2 K. Dielectric constant shows a broad peak at ca. 50 K with dielectric dispersion resembling diffuse phase transition. The relaxation time, however, follows a simple (non-freezing) thermally activated process with an activation energy of 92 meV and an attempt frequency of f0 = 5.79 × 1012 Hz. A thermal conductivity of EuTa2O6 shows a low-temperature (T ≈ 30 K) "plateau" region reminiscent of a glass-like behaviour in Nb-based TTB compounds. This behaviour can be attributed to the loosely bound Eu2+ ions occupying large tricapped trigonal prismatic sites in the EuTa2O6 structure.

  11. Application of LiTaO{sub 3} pyroelectric crystal for pulsed neutron detection

    Energy Technology Data Exchange (ETDEWEB)

    Liang, W.F., E-mail: liang_wen_feng@163.com [CAEP Key Laboratory of Neutron Physics, Mianyang 621900 (China); Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900 (China); Lu, Y.; Wu, J.; Gao, H.; Li, M. [CAEP Key Laboratory of Neutron Physics, Mianyang 621900 (China); Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900 (China)

    2016-08-11

    The feasibility of a LiTaO{sub 3} pyroelectric crystal for pulsed neutron detection has been studied. The detector consists of a slice of electroded Z-cut LiTaO{sub 3} pyroelectric crystal, and no additional neutron converter is required owing to the Li contained in the crystal. The slight temperature increase caused by neutron radiation will lead to the release of bound charges and will give rise to a pyroelectric signal. The response of it has been studied both theoretically and experimentally. Our preliminary experiment on the CFBR-II reactor suggests that the LiTaO{sub 3} pyroelectric detector is promising for high intensity neutron – pulse measurement. - Highlights: • LiTaO{sub 3} pyroelectric neutron detector can be used with no additional neutron converter. • Relationship between the pulsed neutron field and the voltage signal was obtained. • Experiment was carried out to test the response of LiTaO{sub 3} detector. • Feasibility of LiTaO{sub 3} for intense neutron pulse measurement was confirmed.

  12. Optical signature of Weyl electronic structures in tantalum pnictides Ta P n (P n = P, As)

    Science.gov (United States)

    Kimura, Shin-ichi; Yokoyama, Hiroko; Watanabe, Hiroshi; Sichelschmidt, Jörg; Süß, Vicky; Schmidt, Marcus; Felser, Claudia

    2017-08-01

    To investigate the electronic structure of Weyl semimetals Ta P n (P n = P, As), optical conductivity [σ (ω )] spectra are measured over a wide range of photon energies and temperatures, and these measured values are compared with band calculations. Two significant structures can be observed: a bending structure at ℏ ω ˜85 meV in TaAs, and peaks at ℏ ω ˜ 50 meV (TaP) and ˜30 meV (TaAs). The bending structure can be explained by the interband transition between saddle points connecting a set of W2 Weyl points. The temperature dependence of the peak intensity can be fitted by assuming the interband transition between saddle points connecting a set of W1 Weyl points. Owing to the different temperature dependence of the Drude weight in both materials, it is found that the Weyl points of TaAs are located near the Fermi level, whereas those of TaP are further away.

  13. Stability and electrocatalytic activity for oxygen reduction in WC + Ta catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Kunchan; Ishihara, Akimitsu; Mitsushima, Shigenori; Kamiya, Nobuyuki; Ota, Ken-ichiro

    2004-09-01

    Tantalum (Ta)-added tungsten carbide (WC) (WC+Ta) was examined in order to obtain surperior characteristics in stability and electrocatalytic activity for the oxygen reduction reaction (ORR) in acid electrolyte. The stability and the electrocatalytic activity of the WC+Ta catalyst were electrochemically investigated and compared to the pure WC. It was proved that the stability of the tungsten carbide was significantly increased by the addition of tantalum compared to the pure WC. The enhanced stability might be due to the formation of the W-Ta alloy in the WC+Ta catalyst. The reduction current of the WC+Ta catalyst for the ORR was observed at a potential of 0.8 V (versus dynamin hydrogen eletrode (DHE)) or less noble potential. This value was about 0.35 V higher than that of the pure WC. The enhanced electrocatalytic activity for the ORR might be caused by the presence of tungsten carbide, which exists on the surface and/or sub-surface.

  14. Microstructure and properties of Si-TaSi2 eutectic in situ composite for field emission

    Institute of Scientific and Technical Information of China (English)

    CUI ChunJuan; ZHANG Jun; HAN Min; CHEN Jun; XU NingSheng; LIU Lin; FU HengZhi

    2007-01-01

    The Si-TaSi2 eutectic in situ composite for field emission is prepared by electron beam floating zone melting (EBFZM) technique on the basis of Czochralski (CZ) crystal growth technique. The directional solidification microstructure and the field emission properties of the Si-TaSi2 eutectic in situ composite prepared by two kinds of crystal growth techniques have been systematically tested and compared.Researches demonstrated that the solidification microstructure of EBFZM can be fined obviously because of the relatively high solidification rate and very high temperature gradient, i.e. both the diameter and inter-rod spacing of the TaSi2 fibers prepared by EBFZM technique were decreased, and the density and the volume fraction of the TaSi2 fibers prepared by EBFZM technique were increased in comparison with that of the TaSi2 fibers prepared by CZ method. Therefore the field emission property of the Si-TaSi2 eutectic in situ composite prepared by EBFZM can be improved greatly, which exhibits better field emission uniformity and straighter F-N curve.

  15. Ab initio study of TaON, an active photocatalyst under visible light irradiation.

    Science.gov (United States)

    Reshak, A H

    2014-06-14

    Tantalum oxynitride has been studied as an active photocatalyst under visible light, using a full potential linearized augmented plane wave method within the framework of density functional theory. The electronic and optical properties of TaON are calculated using local density approximation (LDA), generalized gradient approximation (GGA), Engel-Vosko generalized gradient approximation (EVGGA) and the modified Becke-Johnson (mBJ) potential approximation to describe the exchange-correlation potential. The calculated band gap value obtained by the mBJ approximation approach (2.5 eV) is very close to the experimental result (2.5 eV). We found that hybridization among the Ta-d, O-p and N-p states results in the formation of a covalent bond between Ta-N and Ta-O. The calculated optical properties confirm that the TaON is an active photocatalyst under visible light irradiation. TaON has a high dielectric constant and the components show anisotropy in the energy range between 3.0 eV and 10.0 eV. A high refractive index of 2.47 at 632.8 nm is obtained which shows better agreement with the experimental value (2.5 at 632.8 nm) than previous results.

  16. On the study of zinc doping in congruent LiTaO{sub 3} crystals

    Energy Technology Data Exchange (ETDEWEB)

    Wu, J.C.; Chen, Z.B. [Department of Chemical Engineering, National Taiwan University, Taipei, 10617, Taiwan (China); Choubey, R.K. [Department of Chemical Engineering, National Taiwan University, Taipei, 10617, Taiwan (China); Department of Applied Physics, Birla Institute of Technology, Mesra, Ranchi 835 215 (India); Lan, C.W., E-mail: cwlan@ntu.edu.tw [Department of Chemical Engineering, National Taiwan University, Taipei, 10617, Taiwan (China)

    2012-04-16

    Highlights: Black-Right-Pointing-Pointer Crack-free congruent Zn:LiTaO{sub 3} grown for various Zn concentrations. Black-Right-Pointing-Pointer Crystal properties for Zn/Ta up to 0.047. Black-Right-Pointing-Pointer 4.7 mol% Zn:LiTaO{sub 3} crystals grown from 15 mol% Zn raw material. - Abstract: Zn-doped congruent LiTaO{sub 3} single crystals have been grown by the Czochralski technique for various doping concentrations. The as-grown crystals were transparent and void-free. The crystals were characterized by the measurements of composition (by inductively coupled plasma atomic emission spectroscopy (ICP-AES)), UV absorption edge, Curie temperature, refractive index, and Fourier transform infrared spectroscopy (FTIR). During the growth we observed that after a certain amount, it was difficult to add more Zn into the grown crystal due to its high volatility and low segregation coefficient. From the ICP-AES study, we also found that the Li/Ta ratio was decreased with the increasing Zn/Ta ratio. The blue shift in absorption edge was observed in Zn doped crystals as compared with the undoped ones. The Curie temperature increased with the increasing Zn concentration and the position of OH{sup -} ions was studied by FTIR as well.

  17. Extraordinary high strength Ti-Zr-Ta alloys through nanoscaled, dual-cubic spinodal reinforcement.

    Science.gov (United States)

    Biesiekierski, Arne; Ping, Dehai; Li, Yuncang; Lin, Jixing; Munir, Khurram S; Yamabe-Mitarai, Yoko; Wen, Cuie

    2017-02-02

    While titanium alloys represent the current state-of-the-art for orthopedic biomaterials, concerns still remain over their modulus. Circumventing this via increased porosity requires high elastic admissible strains, yet also limits traditional thermomechanical strengthening techniques. To this end, a novel β-type Ti-Zr-Ta alloy system, comprised of Ti-45Zr-10Ta, Ti-40Zr-14Ta, Ti-35Zr-18Ta and Ti-30Zr-22Ta, was designed and characterized mechanically and microstructurally. As-cast, this system displayed extremely high yield strengths and elastic admissible strains, up to 1.4GPa and potentially 1.48%, respectively. This strength was attributed to a nanoscaled, cuboidal structure of semi-coherent, dual body-centered cubic (BCC) phases, arising from the thermodynamics of interaction between Ta and Zr; this morphology occurring with dual BCC-phases is heretofore unreported in Ti-based alloys. Further, cell proliferation investigated by MTS assay suggests this was achieved without sacrificing biocompatibility, with no significant difference to either empty-well or commercially-pure Ti controls noted.

  18. Characterization and wear properties of nanoscaled TiN/TaN multilayer coatings

    Institute of Scientific and Technical Information of China (English)

    AN Jian; ZHANG Qing-yu

    2006-01-01

    The structural, morphological, mechanical and tribological characterization of nanoscaled multilayer TiN/TaN coatings deposited by magnetron sputtering technology were investigated by low angle X-ray diffractometry, high angle X-ray diffractometry, atomic force microscopy, microhardness, pin-on-disc testing and 3-D surface profiler. The results show that the TiN/TaN coatings exhibit good modulation period and sharp interface between TiN and TaN layers. In mutilayered TiN/TaN coatings, TiN layers have cubic structure, but hexagonal structure emerged among TaN layers besides cubic structure as modulation period is beyond 8.5 nm. The microhardness is affected by modulation period and the maximum hardness value of 31.5 GPa appears at a modulation period of 8.5 nm. The coefficient of friction is high and the wear resistance is improved for TiN/TaN coatings compared with those of TiN coating; the wear mechanism exhibits predominantly ploughing, material transfer and localized spallation.

  19. Manipulating charge density waves in 1 T -TaS2 by charge-carrier doping: A first-principles investigation

    Science.gov (United States)

    Shao, D. F.; Xiao, R. C.; Lu, W. J.; Lv, H. Y.; Li, J. Y.; Zhu, X. B.; Sun, Y. P.

    2016-09-01

    The transition-metal dichalcogenide 1 T -TaS2 exhibits a rich set of charge-density-wave (CDW) orders. Recent investigations suggested that using light or an electric field can manipulate the commensurate CDW (CCDW) ground state. Such manipulations are considered to be determined by charge-carrier doping. Here we use first-principles calculations to simulate the carrier-doping effect on the CCDW in 1 T -TaS2 . We investigate the charge-doping effects on the electronic structures and phonon instabilities of the 1 T structure, and we analyze the doping-induced energy and distortion ratio variations in the CCDW structure. We found that both in bulk and monolayer 1 T -TaS2 , the CCDW is stable upon electron doping, while hole doping can significantly suppress the CCDW, implying different mechanisms of such reported manipulations. Light or positive perpendicular electric-field-induced hole doping increases the energy of the CCDW, so that the system transforms to a nearly commensurate CDW or a similar metastable state. On the other hand, even though the CCDW distortion is more stable upon in-plane electric-field-induced electron injection, some accompanied effects can drive the system to cross over the energy barrier from the CCDW to a nearly commensurate CDW or a similar metastable state. We also estimate that hole doping can introduce potential superconductivity with a Tc of 6-7 K. Controllable switching of different states such as a CCDW/Mott insulating state, a metallic state, and even a superconducting state can be realized in 1 T -TaS2 . As a result, this material may have very promising applications in future electronic devices.

  20. The Triple Salt Sr14[Ta4N13][TaN4]O-A Nitridotantalate Oxide with 19-fold Rock Salt Superstructure.

    Science.gov (United States)

    Wörsching, Matthias; Daiger, Martin; Hoch, Constantin

    2017-02-21

    A new structure motif in nitridometalate chemistry is the tetracatena-nitridotantalate anion [Ta4N13](19-). It occurs in the crystal structure of the triple salt Sr14[Ta4N13][TaN4]O (monoclinic, space group P21/c with a = 15.062(2) Å, b = 7.2484(6) Å, c = 24.266(3) Å, and β = 97.280(10)(o)) together with ortho-tantalate and isolated oxide anions. Synthesis followed a new approach with employment of Sr surplus and reductive conditions aimed at the preparation of subvalent compounds. The new structure type was established on the basis of single-crystal X-ray diffraction data and also Rietveld refinement. It is a complex superstructure of the rock salt structure type with Ta and Sr atoms forming the face-centered cubic packing and N and O atoms occupying 18/19 of the octahedral voids. We discuss structure and stability of the triple salt with respect to other known nitridometalates and the use of this triple salt for preparative access toward new metal-rich compounds in this field.

  1. Electrochemical behavior of nanocrystalline Ta/TaN multilayer on 316L stainless steel: Novel bipolar plates for proton exchange membrane fuel-cells

    Science.gov (United States)

    Alishahi, M.; Mahboubi, F.; Mousavi Khoie, S. M.; Aparicio, M.; Hübner, R.; Soldera, F.; Gago, R.

    2016-08-01

    Insufficient corrosion resistance and surface conductivity are two main issues that plague large-scale application of stainless steel (SS) bipolar plates in proton exchange membrane fuel cells (PEMFCs). This study explores the use of nanocrystalline Ta/TaN multilayer coatings to improve the electrical and electrochemical performance of polished 316L SS bipolar plates. The multilayer coatings have been deposited by (reactive) magnetron sputtering and characterized by X-ray diffraction, field-emission scanning electron microscopy and transmission electron microscopy. The electrochemical behavior of bare and coated substrates has been evaluated in simulated PEMFC working environments by potentiodynamic and potentiostatic polarization tests at ambient temperature and 80 °C. The results show that the Ta/TaN multilayer coating increases the polarization resistance of 316L SS by about 30 and 104 times at ambient and elevated temperatures, respectively. The interfacial contact resistance (ICR) shows a low value of 12 mΩ × cm2 before the potentiostatic test. This ICR is significantly lower than for the bare substrate and remains mostly unchanged after potentiostatic polarization for 14 h. In addition, the high contact angle (92°) with water for coated substrates indicates a hydrophobic character, which can improve the water management within the cell in PEMFC stacks.

  2. Influence of inserted Mo layer on the thermal stability of perpendicularly magnetized Ta/Mo/Co20Fe60B20/MgO/Ta films

    Directory of Open Access Journals (Sweden)

    Minghua Li

    2016-04-01

    Full Text Available We studied the thermal stability of perpendicular magnetic anisotropy (PMA in Ta/Mo/CoFeB/MgO/Ta films with and without inserted Mo layers. In the absence of a Mo layer, the films show PMA at annealing temperatures below 300 °C. On the other hand, the insertion of a Mo layer preserves PMA at annealing temperatures of up to 500 °C; however, a higher annealing temperature leads to the collapse of PMA. X-ray photoelectron spectroscopy (XPS and high-resolution transmission electron microscopy (HRTEM were used to study the microstructure of the films to understand the deterioration of PMA. The XPS results show that the segregation of Ta is partly suppressed by inserting a Mo layer. Once inserted, Mo does not remain at the interface of Ta and CoFeB but migrates to the surface of the films. The HRTEM results show that the crystallization of the MgO (001 texture is improved owing to the higher annealing temperature of the Mo inserted sample. A smooth and clear CoFeB/MgO interface is evident. The inserted Mo layer not only helps to obtain sharper and smoother interfaces but also contributes to the crystallization after the higher annealing temperature of films.

  3. Road Safety Data, Collection, Transfer and Analysis DaCoTa. Workpackage 4, Decision Support: Deliverable 4.8: DaCoTA Webtexts.

    NARCIS (Netherlands)

    Elvik, R. Risser, R. Tingval, C. Thomas, P. Togni, T. & Twisk, D.A.M. (Eds.) Houwing, S. Vlakveld, W.P. Davidse, R.J. Breen, J. Lynam, D. Schagen, I.N.L.G. van Goldenbeld, C. Townsend, E. & Auserer, K.

    2015-01-01

    One of the valuable products that were initialised in SafetyNet, are the web texts on a number of relevant road safety issues. Within DaCoTA, these web texts have been updated and also a few issues have been added. Another aim regarding the web texts was to organise them better in order to prevent p

  4. Uncertainty reduction and parameters estimation of a~distributed hydrological model with ground and remote sensing data

    Science.gov (United States)

    Silvestro, F.; Gabellani, S.; Rudari, R.; Delogu, F.; Laiolo, P.; Boni, G.

    2014-06-01

    During the last decade the opportunity and usefulness of using remote sensing data in hydrology, hydrometeorology and geomorphology has become even more evident and clear. Satellite based products often provide the advantage of observing hydrologic variables in a distributed way while offering a different view that can help to understand and model the hydrological cycle. Moreover, remote sensing data are fundamental in scarce data environments. The use of satellite derived DTM, which are globally available (e.g. from SRTM as used in this work), have become standard practice in hydrologic model implementation, but other types of satellite derived data are still underutilized. In this work, Meteosat Second Generation Land Surface Temperature (LST) estimates and Surface Soil Moisture (SSM) available from EUMETSAT H-SAF are used to calibrate the Continuum hydrological model that computes such state variables in a prognostic mode. This work aims at proving that satellite observations dramatically reduce uncertainties in parameters calibration by reducing their equifinality. Two parameter estimation strategies are implemented and tested: a multi-objective approach that includes ground observations and one solely based on remotely sensed data. Two Italian catchments are used as the test bed to verify the model capability in reproducing long-term (multi-year) simulations.

  5. Estimation of underwater visibility in coastal and inland waters using remote sensing data.

    Science.gov (United States)

    Kulshreshtha, Anuj; Shanmugam, Palanisamy

    2017-04-01

    An optical method is developed to estimate water transparency (or underwater visibility) in terms of Secchi depth (Z sd ), which follows the remote sensing and contrast transmittance theory. The major factors governing the variation in Z sd , namely, turbidity and length attenuation coefficient (1/(c + K d ), c = beam attenuation coefficient; K d  = diffuse attenuation coefficient at 531 nm), are obtained based on band rationing techniques. It was found that the band ratio of remote sensing reflectance (expressed as (R rs (443) + R rs (490))/(R rs (555) + R rs (670)) contains essential information about the water column optical properties and thereby positively correlates to turbidity. The beam attenuation coefficient (c) at 531 nm is obtained by a linear relationship with turbidity. To derive the vertical diffuse attenuation coefficient (K d ) at 531 nm, K d (490) is estimated as a function of reflectance ratio (R rs (670)/R rs (490)), which provides the bio-optical link between chlorophyll concentration and K d (531). The present algorithm was applied to MODIS-Aqua images, and the results were evaluated by matchup comparisons between the remotely estimated Z sd and in situ Z sd in coastal waters off Point Calimere and its adjoining regions on the southeast coast of India. The results showed the pattern of increasing Z sd from shallow turbid waters to deep clear waters. The statistical evaluation of the results showed that the percent mean relative error between the MODIS-Aqua-derived Z sd and in situ Z sd values was within ±25%. A close agreement achieved in spatial contours of MODIS-Aqua-derived Z sd and in situ Z sd for the month of January 2014 and August 2013 promises the model capability to yield accurate estimates of Z sd in coastal, estuarine, and inland waters. The spatial contours have been included to provide the best data visualization of the measured, modeled (in situ), and satellite-derived Z sd products. The modeled and satellite-derived

  6. 金属醇盐法制备Ta2O5气凝胶%Preparation of Ta2O5 aerogel with metal alkoxide method

    Institute of Scientific and Technical Information of China (English)

    杨静; 任洪波; 毕于铁; 罗炫

    2011-01-01

    With metal alkoxide as precursor. Ta2O5 aerogels were prepared by sol-gel technique. The sol-gel process is found to be affected by water amount, catalyst amount and concentration of Ta(OC2 H5 )5. The gelation can only happen in the presence of strong acid as catalyst, and with the increase of acid strength, the gelation time is obviously decreased. With the con-tinuous increase of water, the gelation time lengthens and then tends to be constant. Additionally, the gelation time increases and the theoretical density of Ta2 O5 aerogel decreases as the solvent amount increases. Through sol-gel process control along with su-percritical drying technique, the Ta2Os aerogel with a low density of 44 mg/cm3 was prepared.%以乙醇钽为前驱物,采用金属醇盐溶胶-凝胶技术,获得了Ta2O5湿凝胶,分析了不同条件下的溶胶-凝胶过程,并初步探讨了凝胶过程机理.Ta2O5的溶胶-凝胶过程主要受到水量、催化剂用量及钽源浓度等因素的影响:体系在强酸性条件下凝胶,且随着酸性的增强,体系凝胶时间明显缩短;当水量较少时,凝胶时间随水量的增加而增加,但当水量增加到一定程度时,体系凝胶时间基本不变;实验证明,通过增大溶剂用量,体系凝胶时间延长,气凝胶理论密度降低.通过对溶胶-凝胶过程的控制,结合超临界干燥技术,获得了密度低至44 mg/cm3的Ta2O5气凝胶样品.

  7. Surface characterization and preparation of Ta coating on Ti6Al4V alloy

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Xiaoming, E-mail: xmyu@imr.ac.cn; Tan, Lili; Yang, Huazhe; Yang, Ke

    2015-09-25

    Highlights: • Ta coating was made on both plate and porous Ti alloy. • The quality of coating depends on H{sub 2} gas flow and T{sub s}. • The corrosion resistance is improved by Ta coating. - Abstract: In this study, high quality Ta coating was made on both plate and porous Ti6Al4V alloy substrates by atmospheric pressure chemical vapor deposition (APCVD) in order to further improve the corrosion resistance and biocompatibility of Ti alloys for medical application. XRD analyses showed that the coatings were mainly composed of Ta with the substrate temperature (T{sub s}) of 1000 °C, 950 °C and 900 °C. The morphology, microstructure and elements composition were characterized by optical microscope, scanning electron microscopy (SEM), atomic force microscopy (AFM) and energy-dispersive spectroscopy (EDS). It was found that the coating surface became much more smooth and uniform at low H{sub 2} gas flow rate of 120 mL/min, and the root-mean-square (RMS) roughness was decreased with the increase of T{sub s}. The wettability of Ta coating was investigated by measuring contact angel of water and α-bromonaphthalene (α-BrNp). The Ta coating with T{sub s} of 950 °C showed the lowest of γ{sub s}, γ{sub s}{sup d} and γ{sub s}{sup d}/γ{sub s}{sup p}, indicating a better hemocompatibility of the Ta coating than that of substrate. The corrosion behavior of the coating was studied by electrochemical test in 0.9% NaCl solution at 37 °C. The Ta coating exhibited higher corrosion potential (E{sub corr}) and lower corrosion current density (i{sub corr}), indicating an improved corrosion resistance compared with the Ti6Al4V substrate. Ta coating was fabricated not only on the plate substrate, but also on a porous Ti6Al4V substrate. The above results made it possible to develop a novel class of Ta-coated Ti alloy implants with wide clinical applications.

  8. Molecular Cloning and Characterization of TaLon1 Gene in Wheat%小麦TaLon1基因克隆与分析

    Institute of Scientific and Technical Information of China (English)

    刘立科; 郭小丽; 刘冬成; 刘春光; 王化波; 张爱民

    2005-01-01

    在酵母和人类中,依赖于ATP的Lon蛋白酶起着降解线粒体内非正常蛋白质和维持线粒体DNA的稳定等重要作用.本研究应用RT-PCR和RACE技术,克隆了小麦Lon蛋白酶家族的一个基因,命名为TaLon1.TaLon1和籼稻Lon1、玉米Lon1的相似性分别为94%和92%.表达分析表明,TaLon1在小麦根、叶和花药中均表现组成型表达,表明该基因在小麦的生长发育过程中很重要,起着类似管家基因的作用.在菜豆上已经间接证明Lon蛋白酶与细胞质雄性不育有一定的相关性.但在本研究中, TaLon1的表达在小麦K型细胞质雄性不育系和其他育性正常的品系之间没有差别.与大肠杆菌和酵母中的Lon基因不同,TaLon1不能被90 min的42℃热激所诱导.另外,250 mmol/L NaCl处理24 h后,该基因的表达量下降.%The ATP-dependent Lon protease plays an important role in removal of the abnormal proteins and maintaining mtDNA integrity in yeast and human. In this paper, using RT-PCR and RACE techniques, a gene that encodes a product belonging to the Lon protease family was isolated from wheat. This gene, designated as TaLon1 with similarity of 94% to Lon1 in indica rice and 92% to Lon1 in maize, was predicted to encode an 886 amino acid protein. TaLon1 showed a constitutive expression pattern in wheat, which indicating its housekeeping role in wheat. It has been indirectly demonstrated that the Lon protease was probably relevant to cytoplasmic male sterility (CMS) in common bean. But there was no difference in expression of TaLon1 between CMS lines with Agiolops kotschyi cytoplasm and normal lines in wheat. Unlike the Lon gene in yeast and E. coli, the TaLon1 didn't respond to heat-shock at 42℃ for 90 min. Furthermore, the expression of TaLon1 was reduced by salt treatment with 250 mmol/L NaCl for 24 h.

  9. Strengthening effect of nano-scaled precipitates in Ta alloying layer induced by high current pulsed electron beam

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Guangze; Luo, Dian; Fan, Guohua [School of Material Science & Engineering, Harbin Institute of Technology, Harbin 150001 (China); Ma, Xinxin, E-mail: maxin@hit.edu.cn [State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin 150001 (China); Wang, Liqin [School of Mechatronics Engineering, Harbin Institute of Technology, Harbin 150001 (China)

    2017-05-01

    Highlights: • Ta alloying layer are fabricated by magnetron sputtering and high current pulsed electron beam. • Nano-scaled TaC precipitates forms within the δ-Fe grain after tempering treatment. • The mean diameter of TaC particles is about 5–8 nm. • The hardness of alloying layer increased by over 50% after formation of nano-scaled TaC particle. - Abstract: In this study, the combination of magnetron sputtering and high current pulsed electron beam are used for surface alloying treatment of Ta film on high speed steel. And the Ta alloying layer is about 6 μm. After tempering treatment, TaC phase forms in Ta alloying layer when the treated temperature is over 823 K. Through the TEM and HRTEM observation, a large amount of nano-scaled precipitates (mean diameter 5–8 nm) form within the δ-Fe grain in Ta alloying layer after tempering treatment and these nano-scaled precipitates are confirmed as TaC particles, which contribute to the strengthening effect of the surface alloying layer. The hardness of tempered alloying layer can reach to 18.1 GPa when the treated temperature is 823 K which increase by 50% comparing with the untreated steel sample before surface alloying treatment.

  10. Potential Utility of the Real-Time TMPA-RT Precipitation Estimates in Streamflow Prediction

    Science.gov (United States)

    Su, Fengge; Gao, Huilin; Huffman, George J.; Lettenmaier, Dennis P.

    2010-01-01

    We investigate the potential utility of the real-time Tropical Rainfall Measuring Mission (TRMM) Multi-satellite Precipitation Analysis (TMPA-RT) data for streamflow prediction, both through direct comparisons of TMPA-RT estimates with a gridded gauge product, and through evaluation of streamflow simulations over four tributaries of La Plata Basin (LPB) in South America using the two precipitation products. Our assessments indicate that the relative accuracy and the hydrologic performance of TMPA-RT-based streamflow simulations generally improved after February 2005. The improvements in TMPA-RT since 2005 are closely related to upgrades in the TMPA-RT algorithm in early February, 2005 which include use of additional microwave sensors (AMSR-E and AMSU-B) and implementation of different calibration schemes. Our work suggests considerable potential for hydrologic prediction using purely satellite-derived precipitation estimates (no adjustments by in situ gauges) in parts of the globe where in situ observations are sparse.

  11. A new look at ocean carbon remineralization for estimating deepwater sequestration

    DEFF Research Database (Denmark)

    Guidi, L.; Legendre, L.; Reygondeau, Gabriel;

    2015-01-01

    provinces, where these estimates range between -50 and +100% of the commonly used globally uniform remineralization value. We apply the regionalized values to satellite-derived estimates of upper ocean POC export to calculate regionalized and ocean-wide deep carbon fluxes and sequestration. The resulting...... the water column. Most of the sinking POC is remineralized during its downward transit, and modest changes in remineralization have substantial feedback on atmospheric CO2 concentrations, but little is known about global variability in remineralization. Here we assess this variability based on modern...... value of global organic carbon sequestration at 2000m is 0.33PgCyr-1, and 0.72PgCyr-1 at the depth of the top of the permanent pycnocline, which is up to 3 times higher than the value resulting from the commonly used approach based on uniform remineralization and constant sequestration depth...

  12. A wheat cinnamyl alcohol dehydrogenase TaCAD12 contributes to host resistance to the sharp eyespot disease

    Directory of Open Access Journals (Sweden)

    Wei Rong

    2016-11-01

    Full Text Available Sharp eyespot, caused mainly by the necrotrophic fungus Rhizoctonia cerealis, is a destructive disease in hexaploid wheat (Triticum aestivum L.. In Arabidopsis, certain cinnamyl alcohol dehydrogenases (CADs have been implicated in monolignol biosynthesis and in defense response to bacterial pathogen infection. However, little is known about CADs in wheat defense responses to necrotrophic or soil-borne pathogens. In this study, we isolate a wheat CAD gene TaCAD12 in response to R. cerealis infection through microarray-based comparative transcriptomics, and study the enzyme activity and defense role of TaCAD12 in wheat. The transcriptional levels of TaCAD12 in sharp eyespot-resistant wheat lines were significantly higher compared with those in susceptible wheat lines. The sequence and phylogenetic analyses revealed that TaCAD12 belongs to IV group in CAD family. The biochemical assay proved that TaCAD12 protein is an authentic CAD enzyme and possesses catalytic efficiencies towards both coniferyl aldehyde and sinapyl aldehyde. Knock-down of TaCAD12 transcript significantly repressed resistance of the gene-silenced wheat plants to sharp eyespot caused by R. cerealis, whereas TaCAD12 overexpression markedly enhanced resistance of the transgenic wheat lines to sharp eyespot. Furthermore, certain defense genes (Defensin, PR10, PR17c, and Chitinase1 and monolignol biosynthesis-related genes (TaCAD1, TaCCR, and TaCOMT1 were up-regulated in the TaCAD12-overexpressing wheat plants but down-regulated in TaCAD12-silencing plants. These results suggest that TaCAD12 positively contributes to resistance against sharp eyespot through regulation of the expression of certain defense genes and monolignol biosynthesis-related genes in wheat.

  13. Electrical and Electrochemical Properties of Nitrogen-Containing Tetrahedral Amorphous Carbon (ta-C) Thin Films

    Science.gov (United States)

    Yang, Xingyi

    Tetrahedral amorphous carbon (ta-C) is a diamond-like carbon (DLC) material comprised of a mixture of sp2 (˜40%) and sp3-bonded (˜60%) carbon domains. The physicochemical structure and electrochemical properties depend strongly on the sp2/sp3 bonding ratio as well as the incorporation of impurities, such as hydrogen or nitrogen. The ability to grow ta-C films at lower temperatures (25-100 °C) on a wider variety of substrates is a potential advantage of these materials as compared with diamond films. In this project, the basic structural and electrochemical properties of nitrogen-incorporated ta-C thin films will be discussed. The major goal of this work was to determine if the ta-C:N films exhibit electrochemical properties more closely aligned with those of boron-doped diamond (sp 3 carbon) or glassy carbon (amorphous sp2 carbon). Much like diamond, ta-C:N thin-film electrodes are characterized by a low background voltammetric current, a wide working potential window, relatively rapid electron-transfer kinetics for aqueous redox systems, such as Fe(CN) 6-3/-4 and Ru(NH3)6+3/+2 , and weak adsorption of polar molecules from solution. For example, negligible adsorption of methylene blue was found on the ta-C:N films in contrast to glassy carbon; a surface on which this molecule strongly adsorbs. The film microstructure was studied with x-ray photoelectron microscopy (XPS), visible Raman spectroscopy and electron-energy loss spectroscopy (EELS); all of which revealed the sp2-bonded carbon content increased with increasing nitrogen. The electrical properties of ta-C:N films were studied by four-point probe resistance measurement and conductive-probe AFM (CP-AFM). The incorporation of nitrogen into ta-C films increased the electrical conductivity primarily by increasing the sp2-bonded carbon content. CP-AFM showed the distribution of the conductive sp2-carbon on the film surface was not uniform. These films have potential to be used in field emission area. The

  14. Optimization of TaDREB3 gene expression in transgenic barley using cold-inducible promoters.

    Science.gov (United States)

    Kovalchuk, Nataliya; Jia, Wei; Eini, Omid; Morran, Sarah; Pyvovarenko, Tatiana; Fletcher, Stephen; Bazanova, Natalia; Harris, John; Beck-Oldach, Kontanze; Shavrukov, Yuri; Langridge, Peter; Lopato, Sergiy

    2013-08-01

    Constitutive over-expression of the TaDREB3 gene in barley improved frost tolerance of transgenic plants at the vegetative stage of plant development, but leads to stunted phenotypes and 3- to 6-week delays in flowering compared to control plants. In this work, two cold-inducible promoters with contrasting properties, the WRKY71 gene promoter from rice and the Cor39 gene promoter from durum wheat, were applied to optimize expression of TaDREB3. The aim of the work was to increase plant frost tolerance and to decrease or prevent negative developmental phenotypes observed during constitutive expression of TaDREB3. The OsWRKY71 and TdCor39 promoters had low-to-moderate basal activity and were activated by cold treatment in leaves, stems and developing spikes of transgenic barley and rice. Expression of the TaDREB3 gene, driven by either of the tested promoters, led to a significant improvement in frost tolerance. The presence of the functional TaDREB3 protein in transgenic plants was confirmed by the detection of strong up-regulation of cold-responsive target genes. The OsWRKY71 promoter-driven TaDREB3 provides stronger activation of the same target genes than the TdCor39 promoter. Analysis of the development of transgenic plants in the absence of stress revealed small or no differences in plant characteristics and grain yield compared with wild-type plants. The WRKY71-TaDREB3 promoter-transgene combination appears to be a promising tool for the enhancement of cold and frost tolerance in crop plants but field evaluation will be needed to confirm that negative development phenotypes have been controlled.

  15. Ni-based Ni-Fe-B-Si-Ta bulk metallic glasses

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The glass-forming ability and properties of Ni-based Ni-Fe-B-Si-Ta bulk metallic glasses are explored in this work. The alloy compositions are determined by using a combination of the cluster line approach, the multi-alloying strategy and the substitutions of similar elements. Bulk metallic glasses with diameters of 3 mm take shape at compositions formulated under the clus- ter-plus-glue-atom model [M9B]B~[(Ni1-xFex)7.71(Si0.66Ta0.34)1.29B]B0.94=(Ni1-xFex)70.5B17.7Si7.8Ta4, x=0.35–0.45, where the bracketed part is the cluster and the unbracketed part is the glue atoms. These alloys exhibit good magnetic properties. The maximum Is is found in the (Ni0.55Fe0.45)70.5B17.7Si7.8Ta4 alloy which reaches 0.51 T, with its Hc as low as 8.5 A/m. Interestingly, these alloys display dual glass transitions at (Ni0.65Fe0.35)70.5B17.7Si7.8Ta4, (Ni0.60Fe0.4)70.5B17.7Si7.8Ta4 and (Ni0.55Fe0.45)70.5B17.7- Si7.8Ta4 as unveiled by Temperature-Modulated Differential Scanning Calorimetry.

  16. Time Series Vegetation Aerodynamic Roughness Fields Estimated from MODIS Observations

    Science.gov (United States)

    Borak, Jordan S.; Jasinski, Michael F.; Crago, Richard D.

    2005-01-01

    Most land surface models used today require estimates of aerodynamic roughness length in order to characterize momentum transfer between the surface and atmosphere. The most common method of prescribing roughness is through the use of empirical look-up tables based solely on land cover class. Theoretical approaches that employ satellite-based estimates of canopy density present an attractive alternative to current look-up table approaches based on vegetation cover type that do not account for within-class variability and are oftentimes simplistic with respect to temporal variability. The current research applies Raupach s formulation of momentum aerodynamic roughness to MODIS data on a regional scale in order to estimate seasonally variable roughness and zero-plane displacement height fields using bulk land cover parameters estimated by [Jasinski, M.F., Borak, J., Crago, R., 2005. Bulk surface momentum parameters for satellite-derived vegetation fields. Agric. For. Meteorol. 133, 55-68]. Results indicate promising advances over look-up approaches with respect to characterization of vegetation roughness variability in land surface and atmospheric circulation models.

  17. 缺失TA35R基因减毒天坛株痘苗病毒的构建及筛选%Construction and selection of the attenuated vaccinia Tiantan strain with deleted TA35R gene

    Institute of Scientific and Technical Information of China (English)

    姜爽; 阚式绂; 胡宁宁; 陈智飞; 李一权; 周晔; 李霄; 孙丽丽; 金宁一

    2014-01-01

    通过敲除痘苗病毒天坛株(vaccinia virus tiantan strain,VTT)复制非必需基因TA35R,结合双筛选标记及同源重组技术,构建TA35R基因缺失的VTT弱毒株rVTT TA35R.人工合成含有TA35R重组臂、同向loxp序列、早晚期启动子PE/L、EGFP及酶切位点的穿梭质粒pTA35R-EGFP.pTA35R-EGFP和野生型VTT共转染BHK-21细胞,通过绿色荧光蚀斑筛选,构建缺失TA35R基因且含FGFP基因的重组痘苗病毒rVTT TA35R--EGFP+.采用Cre/Loxp系统敲除外源筛选标记EGFP,获得缺失TA35R基因的重组痘苗病毒rVTT-TA35R-,利用PCR方法和电子显微镜对其进行鉴定,通过MTT法检测细胞噬性以评价其减毒效果.结果表明,所构建的痘苗病毒弱毒株rVTT-TA35R完全缺失了TA35R基因和外源筛选标记EGFP,且细胞毒性减弱.

  18. Satellite-derived emissions inventories and detection of missing sources

    Science.gov (United States)

    McLinden, C. A.; Fioletov, V.; Shephard, M.; Krotkov, N. A.; Li, C.; Joiner, J.

    2016-12-01

    Our understanding of the impacts of air pollution on health and the environment, and our ability to predict future levels, is limited by our knowledge of its sources. Here, a global inventory of SO2 emissions, derived from the Ozone Monitoring Instrument (OMI) on the Aura satellite and independent of conventional emissions databases, is presented. Our OMI-based inventory is found to be generally consistent with these conventional inventories. However, since we are also able to detect emission sources (in addition to quantifying their emissions), many SO2 sources were identified that are evidently missing from bottom-up inventories, including nearly 40 large anthropogenic sources pointing to significant discrepancies in some regions such as the Middle-East. The methodology, inventory highlights, and applications to other pollutants (NO2 from OMI and NH3 from the Cross-track Infrared Sounder) will be discussed.

  19. NOAA/NESDIS Satellite Derived Surface Oil Analysis Products

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NESDIS Experimental Marine Pollution Surveillance Report (EMPSR) and the Daily Composite product are new products of the NOAA Satellite Analysis Branch and...

  20. Migratory herbivorous waterfowl track satellite-derived green wave index

    NARCIS (Netherlands)

    Shariatinajafabadi, Mitra; Wang, Tiejun; Skidmore, A.K.; Toxopeus, A.G.; Kölzsch, Andrea; Nolet, Bart; Exo, K-M.; Griffin, L.

    2014-01-01

    Many migrating herbivores rely on plant biomass to fuel their life cycles and have adapted to following changes in plant quality through time. The green wave hypothesis predicts that herbivorous waterfowl will follow the wave of food availability and quality during their spring migration. However, t

  1. Evaluation of satellite derived spectral diffuse attenuation coefficients

    Digital Repository Service at National Institute of Oceanography (India)

    Suresh, T.; Talaulikar, M.; Desa, E.; Mascarenhas, A.A.M.Q.; Matondkar, S.G.P.

    wavelengths and are found to deviate from the measured values in the red band of 670nm. It compared well for lower values of K sub(d) in the blue green bands and overestimated at larger values of K sub(d). The comparison is good within 20% of error for bands...

  2. Relating watershed nutrient loads to satellite derived estuarine water quality

    Science.gov (United States)

    Lehrter, J. C.; Le, C.

    2015-12-01

    Nutrient enhanced phytoplankton production is a cause of degraded estuarine water quality. Yet, relationships between watershed nutrient loads and the spatial and temporal scales of phytoplankton blooms and subsequent water quality impairments remain unquantified for most systems. This is partially due to a lack of observations. In many systems, satellite remote sensing of water quality variables may be used to supplement limited field observations and improve understanding of linkages to nutrients. Here, we present the results from a field and satellite ocean color study that quantitatively links nutrients to variations in estuarine water quality endpoints. The study was conducted in Pensacola Bay, Florida, an estuary in the northern Gulf of Mexico that is impacted by watershed nutrients. We developed new empirical band ratio algorithms to retrieve phytoplankton biomass as chlorophyll a (chla), colored dissolved organic matter (CDOM), and suspended particulate matter (SPM) from the MEdium Resolution Imaging Spectrometer (MERIS). MERIS had suitable spatial resolution (300-m) for the scale of Pensacola Bay (area = 370 km2, mean depth = 3.4 m) and a spectral band centered at wavelength 709 nm that was used to minimize the effect of organic matter on chla retrieval. The algorithms were applied to daily MERIS remote sensing reflectance (level 2) data acquired from 2003 to 2011 to calculate nine-year time-series of mean monthly chla, CDOM, and SPM concentrations. The MERIS derived time-series were then analyzed for statistical relations with time-series of mean monthly river discharge and river loads of nitrogen, phosphorus, dissolved organic carbon, and SPM. Regression analyses revealed significant relationships between river loads and MERIS water quality variables. The simple regression models provide quantitative predictions about how much chla, CDOM, and SPM concentrations in Pensacola Bay will increase with increased river loading, which is necessary information for nutrient, land-use, and climate management decisions. We will discuss the lessons learned for management of Pensacola Bay and about communicating the value of satellite observations to water quality managers.

  3. On the use of satellite-derived CH

    NARCIS (Netherlands)

    Pandey, S.; Houweling, S.; Krol, M.; Aben, I.; Röckmann, T.

    2015-01-01

    We present a method for assimilating total column CH4 : CO2 ratio measurements from satellites for inverse modeling of CH4 and CO2 fluxes using the variational approach. Unlike conventional approaches, in which retrieved CH4 : CO2

  4. Satellite-Derived Extinction at A Desert Site

    Science.gov (United States)

    Walker, P. L.; Blomshield, F. S.

    2002-12-01

    We have been conducting research aimed at enabling determination of desert optical environments from meteorological and satellite observations. To this end we have been making Rotating Shadowband Radiometer measurements, collecting aerosol size distributions, visibility and meteorological data continuously for the past 2 years in the Indian Wells Valley of the Mojave Desert of California. These data present an opportunity to validate satellite retrieval of atmospheric optical depth. Specifically, MISR-derived optical depths are compared to those derived from Shadowband measurements. A crude measure of extinction can be made by dividing the optical depth by the height of the mixing layer. The validity of this procedure is determined by comparison with extinction directly measured by nephelometers and calculated from measured aerosol size distributions.

  5. A Review of Global Satellite-derived Snow Products

    Science.gov (United States)

    Frei, Allan; Tedesco, Marco; Lee, Shihyan; Foster, James; Hall, Dorothy K.; Kelly, Richard; Robinson, David A.

    2012-01-01

    Snow cover over the Northern Hemisphere plays a crucial role in the Earth's hydrology and surface energy balance, and modulates feedbacks that control variations of global climate. While many of these variations are associated with exchanges of energy and mass between the land surface and the atmosphere, other expected changes are likely to propagate downstream and affect oceanic processes in coastal zones. For example, a large component of the freshwater flux into the Arctic Ocean comes from snow melt. The timing and magnitude of this flux affects biological and thermodynamic processes in the Arctic Ocean, and potentially across the globe through their impact on North Atlantic Deep Water formation. Several recent global remotely sensed products provide information at unprecedented temporal, spatial, and spectral resolutions. In this article we review the theoretical underpinnings and characteristics of three key products. We also demonstrate the seasonal and spatial patterns of agreement and disagreement amongst them, and discuss current and future directions in their application and development. Though there is general agreement amongst these products, there can be disagreement over certain geographic regions and under conditions of ephemeral, patchy and melting snow.

  6. Identifying individual fires from satellite-derived burned area data

    CSIR Research Space (South Africa)

    Archibald, S

    2009-07-01

    Full Text Available An algorithm for identifying individual fires from the Modis burned area data product is introduced for southern Africa. This algorithm gives the date of burning, size of fire, and location of the centroid for all fires identified over 8 years...

  7. [Clinicopathological study of the 1973 who classification and the WHO/ISUP classification in pTa bladder carcinoma].

    Science.gov (United States)

    Ishida, Ryo; Tsuzuki, Toyonori; Yoshida, Shinri; Shiota, Takako; Nisikimi, Toshinori; Yamada, Hiroshi; Yokoi, Keisuke; Kobayashi, Hiroaki

    2010-05-01

    To compare the usefulness of the World Health Organization (WHO) 1973 classification with the WHO/International Society of Urological Pathology (ISUP) classification in pTa bladder tumors. A retrospective analysis was performed on 132 patients (107 men and 25 women; mean age 69 years) with a initial diagnosis of pTa bladder carcinoma. Median follow-up were 67 months. On the WHO 1973 classification, histopathological evaluation of initial diagnostic specimens revealed 51 cases with grade1, 68 cases with grade 2, 13 cases with grade3. All histological slides were examined by one genitourinary pathologist blinded with respect to clinical outcome and were classified according to the WHO/ISUP classification. Disease progression was defined as up stage (> or = pT1). Actual probability of progression-free and recurrence-free survival rate were estimated using the Kaplan-Meier method. The Log rank test was used to determine statistical difference between actual curves. Univariate and multivariate analyses were done using Cox regression analysis. The independent variables were multiplicity, histopathological grade, and adjuvant intravesical therapy. The dependent variable was disease progression and recurrence. The tumors were reclassified as low grade carcinoma in 77 and high grade carcinoma in 55. During the follow-up, 68 patients experience recurrence, 14 patients experienced disease progression. On the WHO 1973 classification, the risk of recurrence was significantly lower in patients with grade 1 compared to those with grade3 (p = 0.007). On the WHO/ISUP classification, the risk of recurrence and disease progression were significantly lower in patients with low grade compared to those with high grade (p = 0.003, P = 0.01). After adjustment for tumor multiplicity and adjuvant therapy, the relative risks of recurrence and progression in the low grade carcinoma versus the high grade carcinoma was 2.0 (95% confidence intervals 1.26-3.31), 5.6 (95% confidence intervals 1

  8. Nanodiamond embedded ta-C composite film by pulsed filtered vacuum arc deposition from a single target

    Science.gov (United States)

    Iyer, Ajai; Etula, Jarkko; Ge, Yanling; Liu, Xuwen; Koskinen, Jari

    2016-11-01

    Detonation Nanodiamonds (DNDs) are known to have sp3 core, sp2 shell, small size (few nm) and are gaining importance as multi-functional nanoparticles. Diverse methods have been used to form composites, containing detonation nanodiamonds (DNDs) embedded in conductive and dielectric matrices for various applications. Here we show a method, wherein DND-ta-C composite film, consisting of DNDs embedded in ta-C matrix have been co-deposited from the same cathode by pulsed filtered cathodic vacuum arc method. Transmission Electron Microscope analysis of these films revel the presence of DNDs embedded in the matrix of amorphous carbon. Raman spectroscopy indicates that the presence of DNDs does not adversely affect the sp3 content of DND-ta-C composite film compared to ta-C film of same thickness. Nanoindentation and nanowear tests indicate that DND-ta-C composite films possess improved mechanical properties in comparison to ta-C films of similar thickness.

  9. Effect of sputtering pressure and rapid thermal annealing on optical properties of Ta2O5 thin films

    Institute of Scientific and Technical Information of China (English)

    ZHOU Ji-cheng; LUO Di-tian; LI You-zhen; LIU Zheng

    2009-01-01

    Ta2O5 thin films were deposited by DC reactive magnetron sputtering followed by rapid thermal annealing(RTA). Influence of sputtering pressure and annealing temperature on surface characteristics, microstructure and optical property of Ta2O5 thin films were investigated. As-deposited Ta2O5 thin films are amorphous. It takes hexagonal structure (δ-Ta2O5) after being annealed at 800 ℃. A transition from δ-Ta2O5 to orthorhombic structure (L-Ta2O5) occurs at 900-1 000 ℃. Surface roughness is decreased after annealing at low temperature. Refractive index and extinction coefficient are decreased when annealing temperature is increased.

  10. Mechanisms of Low-Temperature Nitridation Technology on a TaN Thin Film Resistor for Temperature Sensor Applications.

    Science.gov (United States)

    Chen, Huey-Ru; Chen, Ying-Chung; Chang, Ting-Chang; Chang, Kuan-Chang; Tsai, Tsung-Ming; Chu, Tian-Jian; Shih, Chih-Cheng; Chuang, Nai-Chuan; Wang, Kao-Yuan

    2016-12-01

    In this letter, we propose a novel low-temperature nitridation technology on a tantalum nitride (TaN) thin film resistor (TFR) through supercritical carbon dioxide (SCCO2) treatment for temperature sensor applications. We also found that the sensitivity of temperature of the TaN TFR was improved about 10.2 %, which can be demonstrated from measurement of temperature coefficient of resistance (TCR). In order to understand the mechanism of SCCO2 nitridation on the TaN TFR, the carrier conduction mechanism of the device was analyzed through current fitting. The current conduction mechanism of the TaN TFR changes from hopping to a Schottky emission after the low-temperature SCCO2 nitridation treatment. A model of vacancy passivation in TaN grains with nitrogen and by SCCO2 nitridation treatment is eventually proposed to increase the isolation ability in TaN TFR, which causes the transfer of current conduction mechanisms.

  11. The enhancement of ferromagnetism in Ta-doped anatase TiO2 system by iron co-doping

    Science.gov (United States)

    Muhammady, S.; Kurniawan, R.; Nurfani, E.; Sutjahja, I. M.; Winata, T.; Darma, Y.

    2016-11-01

    The ferromagnetic properties of Ta-doped and (Ta,Fe)-doped anatase TiO2 as diluted ferromagnetic materials has been studied within spin-polarized generalized gradient approximation (GGA) and GGA + U method. We observed a ferromagnetic properties in Ta- doped anatase TiO2, with a total magnetic moment of 1.00 μ B /supercell, which mainly arised due to Ti 3d and O 2p states upon Ef. Furthermore, the enhancement of ferromagnetism, mainly arising due to Fe 3d states, in (Ta,Fe)-doped anatase TiO2 was observed up to 5.00 μB /supercell, 5 times larger than that in Ta-doped TiO2. Our results confirmed the important role of Fe doping for the ferromagnetism enhancement in Ta-doped anatase TiO2.

  12. 小麦Ta-hir2基因克隆及转Ta-hir2基因小麦的获得%Cloning of a wheat gene Ta-hir2 and obtaining of transgenic plant of wheat with Ta-hir2

    Institute of Scientific and Technical Information of China (English)

    陈佳平; 孟涛; 刘芬; 于秀梅; 赵伟全; 刘大群

    2011-01-01

    通过基因枪介导法将小麦过敏性诱导反应蛋白2基因Ta-hir2转入小麦胚性愈伤组织中,经分化筛选后获得转基因小麦植株,为验证该基因的功能奠定基础.以接种非亲和叶锈菌小种05-19-43②的小麦‘TcLr15,为材料,采用同源克隆的策略克隆了小麦Ta-hir2基因;将该基因的编码区与植物表达载体pAHC-25相连,成功构建了重组转基因质粒Ta-hir2-pAHC-25;采用基因枪法将构建好的重组质粒转化小麦品种‘Thatcher,和‘TcLr15’的胚性愈伤组织,获得了再生植株;对再生植株提取基因组DNA后,进行PCR检测,经计算,PCR阳性率为4.76%,最终转化率为0.28%.%The purpose of the present study was to obtain transgenic plant of wheat through transforming wheat hypersensitive induced reaction protein 2 gene Ta-hir2 into wheat embryo-genic callus by particle bombardment, and series of differentiation and selection, which would lay a foundation for determining the function of Ta-hir2 in wheat. Ta-hir2 was cloned from wheat (Triticum aestivum L. ) isogenic line 'TcLr15' inoculated with incompatible leaf rust race 05-19-43 ② by homology cloning. The recombinant plasmid Ta-hir2-pAHC-25 was constructed successfully by inserting open reading frame of Ta-hir2 into the plant expression vector pAHC-25. Embryogenic callus initiated from mature embryos of 'Thatcher' and 'TcLrl5' were transformed with recombinant Ta-hir2-pAHC-25 by particle bombardment, and the regenerated seedlings were obtained. Genomic DNA of regenerated seedlings were extracted and subject to PCR detection, the positive ratio for PCR was 4. 76%, ratio of gene transformation was 0.28%.

  13. CO oxidation on Ta-Modified SnO2 solid solution catalysts

    Science.gov (United States)

    Han, Xue; Xu, Xianglan; Liu, Wenming; Wang, Xiang; Zhang, Rongbin

    2013-06-01

    Co-precipitation method was adopted to prepare Sn-Ta mixed oxide catalysts with different Sn/Ta molar ratios and used for CO oxidation. The catalysts were investigated by N2-Brunauer-Emmett-Teller (N2-BET), X-ray diffraction patterns (XRD), H2-temperature programmed reduction (H2-TPR), Thermal Gravity Analysis - Differential Scanning Calorimetry (TGA-DSC) techniques. It is revealed that a small amount of Ta cations can be doped into SnO2 lattice to form solid solution by co-precipitation method, which resulted in samples having higher surface areas, improved thermal stability and more deficient oxygen species on the surface of SnO2. As a result, those Sn rich Sn-Ta solid solution catalysts with an Sn/Ta molar ratio higher than 4/2 showed significantly enhanced activity as well as good resistance to water deactivation. It is noted here that if tantala disperses onto SnO2 surface instead of doping into its lattice, it will then have negative effect on its activity.

  14. Prokaryotic expression of TaSDP gene of Theileria annulata and preparation of polyclonal antibody against TaSDP%环形泰勒虫TaSDP基因的原核表达及TaSDP蛋白多克隆抗体的制备

    Institute of Scientific and Technical Information of China (English)

    杨聪山; 刘军龙; 李有全; 田占成; 赵洪喜; 刘娟; 刘爱红; 任巧云; 牛庆丽

    2015-01-01

    利用PCR技术从环形泰勒虫裂殖体cDNA中扩增TaSDP(Theileria annulata schizont-derived protein)基因,用获得的基因片段构建原核表达载体pET-30a(+)-TaSDP,并在大肠杆菌BL21 (DE3)pLysS中进行表达,蛋白以包涵体的形式存在;融合蛋白经纯化后免疫家兔,制备多克隆抗体,并分别用ELISA和Western-blot测定抗体的效价及特异性.结果显示,获得的TaSDP基因的长度为552 bp,制备的多克隆抗体不仅可与重组蛋白His-TaSDP发生反应,而且可以识别天然的虫体蛋白,效价高于1∶215.上述研究结果为开展TaSDP在细胞调控方面的研究奠定了基础.

  15. Ionizing radiation effects on electrical and reliability characteristics of sputtered Ta2O5/Si interface

    Science.gov (United States)

    Rao, Ashwath; Verma, Ankita; Singh, B. R.

    2015-06-01

    This paper describes the effect of ionizing radiation on the interface properties of Al/Ta2O5/Si metal oxide semiconductor (MOS) capacitors using capacitance-voltage (C-V) and current-voltage (I-V) characteristics. The devices were irradiated with X-rays at different doses ranging from 100 rad to 1 Mrad. The leakage behavior, which is an important parameter for memory applications of Al/Ta2O5/Si MOS capacitors, along with interface properties such as effective oxide charges and interface trap density with and without irradiation has been investigated. Lower accumulation capacitance and shift in flat band voltage toward negative value were observed in annealed devices after exposure to radiation. The increase in interfacial oxide layer thickness after irradiation was confirmed by Rutherford Back Scattering measurement. The effect of post-deposition annealing on the electrical behavior of Ta2O5 MOS capacitors was also investigated. Improved electrical and interface properties were obtained for samples deposited in N2 ambient. The density of interface trap states (Dit) at Ta2O5/Si interface sputtered in pure argon ambient was higher compared to samples reactively sputtered in nitrogen-containing plasma. Our results show that reactive sputtering in nitrogen-containing plasma is a promising approach to improve the radiation hardness of Ta2O5/Si MOS devices.

  16. Crystal structure and molecular modeling study of N-carbamoylsarcosine amidase Ta0454 from Thermoplasma acidophilum

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Hai-Bin; Zheng, Heping; Zimmerman, Matthew D.; Chruszcz, Maksymilian; Skarina, Tatiana; Egorova, Olga; Savchenko, Alexei; Edwards, Aled M.; Minor, Wladek (Sun Yat-Sen); (Toronto); (UV)

    2010-05-12

    A crystal structure of the putative N-carbamoylsarcosine amidase (CSHase) Ta0454 from Thermoplasma acidophilum was solved by single-wavelength anomalous diffraction and refined at a resolution of 2.35 {angstrom}. CSHases are involved in the degradation of creatinine. Ta0454 shares a similar fold and a highly conserved C-D-K catalytic triad (Cys123, Asp9, and Lys90) with the structures of three cysteine hydrolases (PDB codes 1NBA, 1IM5, and 2H0R). Molecular dynamics (MD) simulations of Ta0454/N-carbamoylsarcosine and Ta0454/pyrazinamide complexes were performed to determine the structural basis of the substrate binding pattern for each ligand. Based on the MD-simulated trajectories, the MM/PBSA method predicts binding free energies of -24.5 and -17.1 kcal/mol for the two systems, respectively. The predicted binding free energies suggest that Ta0454 is selective for N-carbamoylsarcosine over pyrazinamide, and zinc ions play an important role in the favorable substrate bound states.

  17. MHC2TA and FCRL3 genes are not associated with rheumatoid arthritis in Mexican patients.

    Science.gov (United States)

    Mendoza Rincón, J F; Rodríguez Elias, A K; Fragoso, J M; Vargas Alarcón, G; Maldonado Murillo, K; Rivas Jiménez, M L; Barbosa Cobos, R E; Jimenez Morales, S; Lugo Zamudio, G; Tovilla Zárate, C; Ramírez Bello, J

    2016-02-01

    Rheumatoid arthritis (RA) is a multifactorial disease. A combination of genetic and environmental risk factors contributes to its etiology. Several genes have been reported to be associated with susceptibility to the development of RA. The MHC2TA and FCRL3 genes have been associated previously with RA in Swedish and Japanese populations, respectively. In two recent reports, we show an association between FCRL3 and juvenile rheumatoid arthritis (JRA), and MHC2TA and acute coronary syndrome (ACS) in Mexican population. We assessed the association between three single nucleotide polymorphisms (SNPs) of the MHC2TA (-168G/A; rs3087456, and +16G/C; rs4774) and FCRL3 (-169T/C; rs7528684) genes and rheumatoid arthritis in Mexican population through a genotyping method using allelic discrimination assays with TaqMan probes. Our case-control study included 249 patients with RA and 314 controls. We found no evidence of an association between the MHC2TA -168G/A and +1614G/C or FCRL3 -169T/C polymorphisms and RA in this Mexican population. In this cohort of Mexican patients with RA, we observed no association between the MHC2TA or FCRL3 genes and this autoimmune disease.

  18. Structural, electronic and optical properties of hexagonal TaN compound

    Science.gov (United States)

    Chen, Zhongjun; Yan, Jungan; Kuang, Zhong; Chen, Taihong; Li, Dehua

    2016-01-01

    Structural and electronic properties of hexagonal Tantalum nitride (TaN) in CoSn and WC structures are studied using the first-principle calculations. Lattice constants and electronic band structures are in an excellent agreement with the available experimental and other theoretical values. TaN in both structures studied has a metallic nature and a strong hybridization of Ta 5d and N 2p are found from the spin density of states (DOS). Meanwhile, our LSDA+U calculations predicted a strong ferromagnetic state for CoSn-type structure and an obvious paramagnetic nature for WC-type structure. No phase transition are observed within cubic and hexagonal CoSn and WC structures under high pressures. Our results show WC-type TaN is the calculated ground-state structure among the three crystallographic structures studied under 120 GPa. Optical properties show that TaN in CoSn-type structure is a better dielectric material.

  19. Perpendicular magnetic anisotropy in composite MgO/CoFeB/Ta/[Co/Pd]n structures

    Science.gov (United States)

    Garcia-Vazquez, Valentin; Chang, Yao-Jen; Canizo-Cabrera, A.; Garzon-Roman, Abel; Wu, Te-ho

    2016-02-01

    The impact of a non-magnetic Ta spacer layer on the perpendicular magnetic anisotropy (PMA) of composite magnetic structures constituted by ultra-thin Co/Pd multilayers (MLs) and MgO/CoFeB was studied. Composite structures lacking a Ta layer present in-plane magnetic anisotropy. The strong perpendicular anisotropy observed in sole Co/Pd MLs is not sufficient to pull the magnetic moment out of the film plane, not even after annealing at 300 or 350 °C. PMA with squareness values close to unity and annealing stability up to 350 °C is observed after the insertion of an ultra-thin Ta layer. Our study demonstrates that Ta layer is essential for obtaining perpendicular magnetic axis in MgO/CoFeB/Ta/[Co/Pd]6. The exchange coupling between the MgO/CoFeB bilayer and the Co/Pd MLs is ferromagnetic with sharp switching characteristics. Perpendicular composite structures with sharp magnetization reversal and annealing stability are relevant in perpendicular CoFeB-based magnetic tunnel junctions for the development of gigabit-scale nonvolatile memory.

  20. The ubiquitin conjugating enzyme, TaU4 regulates wheat defence against the phytopathogen Zymoseptoria tritici

    Science.gov (United States)

    Millyard, Linda; Lee, Jack; Zhang, Cunjin; Yates, Gary; Sadanandom, Ari

    2016-01-01

    Mycosphaerella graminicola (Zymoseptoria tritici commonly known as Septoria), the causal agent of Septoria Leaf Blotch (STB), is considered one of the major threats to European wheat production. Previous studies have shown the importance of ubiquitination in plant defence against a multitude of pathogens. However the ubiquitination machinery in wheat is under studied, particularly E2 enzymes that have the ability to control the ubiquitination and thereby the fate of many different target proteins. In this study we identify an E2 enzyme, Triticum aestivum Ubiquitin conjugating enzyme 4 (TaU4) that functions in wheat defence against Septoria. We demonstrate TaU4 to be a bona fide E2 enzyme through an E2 charging assay. TaU4 localises in both the cytoplasm and nucleus, therefore potentially interacting with E3 ligases and substrate proteins in multiple compartments. Virus Induced Gene Silencing of TaU4 in wheat leaves resulted in delayed development of disease symptoms, reduced Septoria growth and reproduction. We conclude that TaU4 is a novel negative regulator of defence against Septoria. PMID:27759089

  1. Dye Modification Effects on TaON for Photocatalytic Hydrogen Production from Water

    Directory of Open Access Journals (Sweden)

    Tatsumi Ishiahara

    2013-07-01

    Full Text Available Modification effects of porphyrin dyes on the photocatalytic activity of tantalum (oxynitride (TaON were investigated. The nitrogen content in tantalum (oxynitride was increased by increasing the heat treatment period. The optimized nitridation conditions were found to be calcination at 800 °C for 14 h under a NH3 gas flow (25 mL min−1. Among the porphyrin dyes examined, pentamethylene bis[4-(10,15,20-triphenylporphine-5-yl benzoate]-dizinc (II (Zn-TPPD showed the most positive effect on the photocatalytic activity of TaON for H2 production from Na2S aqueous solution. From the results of the photocatalytic reaction using various combinations of catalyst components, it was found that the modification dye and PtOx co-catalysts were necessary to achieving photocatalytic H2 formation. In the PtOx/Zn-TPPD/TaON photocatalyst, the expected charge transfer mechanism was a two-step excitation of both TaON and Zn-TPPD, and the oxidation and reduction sites were TaON and PtOx co-catalyst, respectively. These results indicate that dye modification has the potential to improve the photocatalytic activity of various (oxynitride photocatalysts.

  2. Decay heat calculations for a 500 kW W–Ta spallation target

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Quanzhi, E-mail: qzhyu@iphy.ac.cn [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Lu, Youlian; Hu, Zhiliang; Zhou, Bin [Dongguan Campus, Institute of High Energy Physics, Chinese Academy of Sciences, Dongguan 523800 (China); Dongguan Neutron Science Center, Dongguan 523800 (China); Yin, Wen; Liang, Tianjiao [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China)

    2015-05-15

    The China Spallation Neutron Source (CSNS) is a short-pulsed neutron scattering facility. The beam power is designed to be 100 kW in Phase I, with the capability of upgrading to 500 kW. Tantalum (Ta)-cladded tungsten (W) was chosen as the spallation target due to its high neutron yield. Ta claddings can solve the problem of the corrosiveness of W plates, although they produce high decay heat after intense irradiation. This paper presents the decay heat distributions and evolutions for the future upgraded 500 kW W–Ta spallation target. The calculations are performed using the MCNPX2.5 Monte Carlo code and the CINDER’90 activation code. The decay heat distributions show that for the W plates, decay heat is mainly produced via the spallation reaction process, whereas for the Ta claddings, it is mainly produced via the neutron capture process. An effective method of reducing the decay heat in the W–Ta target is also presented and discussed.

  3. TaSYP71, a Qc-SNARE, Contributes to Wheat Resistance against Puccinia striiformis f. sp. tritici

    Directory of Open Access Journals (Sweden)

    Minjie eLiu

    2016-04-01

    Full Text Available N-ethylmaleimide-sensitive factor attachment protein receptors (SNAREs are involved in plant resistance; however, the role of SYP71 in the regulation of plant–pathogen interactions is not well known. In this study, we characterized a plant-specific SNARE in wheat, TaSYP71, which contains a Qc-SNARE domain. Three homologues are localized on chromosome 1AL, 1BL and 1DL. Using Agrobacterium-mediated transient expression, TaSYP71 was localized to the plasma membrane in Nicotiana benthamiana. Quantitative real-time PCR assays revealed that TaSYP71 homologues was induced by NaCl, H2O2 stress and infection by virulent and avirulent Puccinia striiformis f. sp. tritici (Pst isolates. Heterologous expression of TaSYP71 in Schizosaccharomyces pombe elevated tolerance to H2O2. Meanwhile, H2O2 scavenging gene (TaCAT was downregulated in TaSYP71 silenced plants treated by H2O2 compared to that in control, which indicated that TaSYP71 enhanced tolerance to H2O2 stress possibly by influencing the expression of TaCAT to remove the excessive H2O2 accumulation. When TaSYP71 homologues were all silenced in wheat by the virus-induced gene silencing system, wheat plants were more susceptible to Pst, with larger infection area and more haustoria number, but the necrotic area of wheat mesophyll cells were larger, one possible explanation that minor contribution of resistance to Pst was insufficient to hinder pathogen extension when TaSYP71were silenced, and the necrotic area was enlarged accompanied with the pathogen growth. Of course, later cell death could not be excluded. In addition, the expression of pathogenesis-related genes were down-regulated in TaSYP71 silenced wheat plants. These results together suggest that TaSYP71 play a positive role in wheat defence against Pst.

  4. Functional analysis of TaABF1 during abscisic acid and gibberellin signalling in aleurone cells of cereal grains.

    Science.gov (United States)

    Harris, Lauren J; Martinez, Sarah A; Keyser, Benjamin R; Dyer, William E; Johnson, Russell R

    2013-06-01

    The wheat transcription factor TaABF1 physically interacts with the protein kinase PKABA1 and mediates both abscisic acid (ABA)-induced and ABA-suppressed gene expression. In bombarded aleurone cells of imbibing grains, the effect of TaABF1 in down-regulating the gibberellin (GA)-induced Amy32b promoter was stronger in the presence of exogenous ABA. As these grains contained low levels of endogenous ABA, the effect of TaABF1 may also be mediated by ABA-induced activation even in the absence of exogenous ABA. Levels of TaABF1 protein decreased slightly during imbibition of afterripened grains. However, TaABF1 levels (especially in aleurone layers) were not substantially affected by exogenous ABA or GA, indicating that changes in TaABF1 protein level are not an important part of regulating its role in hormone signalling. We found that TaABF1 was phosphorylated in vivo in aleurone cells, suggesting a role for post-translational modification in regulating TaABF1 activity. Induction of Amy32b by overexpression of the transcription factor GAMyb could not be prevented by TaABF1, indicating that TaABF1 acts upstream of GAMyb transcription in the signalling pathway. Supporting this view, knockdown of TaABF1 by RNA interference resulted in increased expression from the GAMyb promoter. These results are consistent with a model in which TaABF1 is constitutively present in aleurone cells, while its ability to down-regulate GAMyb is regulated in response to ABA.

  5. Effects of Li and Na intercalation on electronic, bonding and thermoelectric transport properties of MX{sub 2} (M = Ta; X = S or Se) dichalcogenides – Ab initio investigation

    Energy Technology Data Exchange (ETDEWEB)

    Meziane, Souheyr; Feraoun, Houda [Unité de Recherche Matériaux et Energies Renouvelables – URMER, Université de Tlemcen (Algeria); Ouahrani, Tarik [Laboratoire de Physique Théorique, Ecole Préparatoire en Sciences et Techniques, B.P. 230, 13000 Tlemcen (Algeria); Esling, Claude, E-mail: claude.esling@univ-lorraine.fr [Laboratoire d’Etude des Microstructures et de Mécanique des Matériaux, LEM3 UMR CNRS 7239, Université de Lorraine UL, Metz 57045 (France); Laboratoire d’Excellence “DAMAS”: Design of Metal Alloys for low-mAss Structures, Université de Lorraine – Metz, Ile du Saulcy, 57045 Metz Cedex 01 (France)

    2013-12-25

    Highlights: •Topological method is used to analyze the chemical bonding in Li(Na)TaX{sub 2} dichalcogenide compounds. •For the first time, Seebeck coefficient, electrical resistivity and thermal conductivity were estimated. •The best figure of merit is established for 2H-LiTaS{sub 2}. •Some new thermoelectric compounds are found. -- Abstract: Using the pseudo-potential method and semi-classical Boltzmann theory, electronic, chemical bonding and thermoelectric transport properties of sample and Li or Na intercalated Ta(S, Se){sub 2} dichalcogenides have been reported. The chemical bonding is studied using the Quantum Theory of Atoms in Molecules (QTAIM). Then, the Seebeck coefficient, electrical resistivity, electrical conductivity, thermal conductivity and figure of merit have been calculated in the temperature range 100–700 K. It was shown that the thermoelectric transport properties strongly depend on the Alkali metals doping and the two main structures 1T- or 2H- as well as the temperature. 2H-LiTaS{sub 2} have been selected as the best candidate for thermoelectrical applications with zT = 1.1.

  6. A Study of Thin Film Resistors Prepared Using Ni-Cr-Si-Al-Ta High Entropy Alloy

    Directory of Open Access Journals (Sweden)

    Ruei-Cheng Lin

    2015-01-01

    Full Text Available Ni-Cr-Si-Al-Ta resistive thin films were prepared on glass and Al2O3 substrates by DC magnetron cosputtering from targets of Ni0.35-Cr0.25-Si0.2-Al0.2 casting alloy and Ta metal. Electrical properties and microstructures of Ni-Cr-Si-Al-Ta films under different sputtering powers and annealing temperatures were investigated. The phase evolution, microstructure, and composition of Ni-Cr-Si-Al-Ta films were characterized by X-ray diffraction (XRD, transmission electron microscopy (TEM, and Auger electron spectroscopy (AES. When the annealing temperature was set to 300°C, the Ni-Cr-Si-Al-Ta films with an amorphous structure were observed. When the annealing temperature was at 500°C, the Ni-Cr-Si-Al-Ta films crystallized into Al0.9Ni4.22, Cr2Ta, and Ta5Si3 phases. The Ni-Cr-Si-Al-Ta films deposited at 100 W and annealed at 300°C which exhibited the higher resistivity 2215 μΩ-cm with −10 ppm/°C of temperature coefficient of resistance (TCR.

  7. Spin–orbit torque induced magnetization switching in Pt/Co/Ta structures with perpendicular magnetic anisotropy

    Science.gov (United States)

    Yun, Jijun; Li, Dong; Cui, Baoshan; Guo, Xiaobin; Wu, Kai; Zhang, Xu; Wang, Yupei; Zuo, Yalu; Xi, Li

    2017-10-01

    Spin–orbit torque (SOT) induced magnetization switching is investigated in Pt/Co/Ta stacks with perpendicular magnetic anisotropy with the variation of the thickness of Ta layer (t Ta). SOT is characterized by an effective spin Hall angle θ SH, which is determined by an anomalous Hall resistance measurements method based on a macrospin model. A high charge current induced magnetization switching efficiency is achieved by the enhanced injection efficiency of spin currents from bottom Pt and top Ta with opposite signs of θ SH. When t Ta  =  4 nm, the enhanced effective θ SH for Pt/Co/Ta shows a maximum value around 0.356, which is larger than the sum of |θ SH| for Pt and Ta and is ascribed to an additional interfacial SOT at Co/Ta interface. θ SH gradually decreases with increasing Ta layer thickness beyond 4 nm, which can be explained by the improved crystallinity of Ta layer. Our results confirm a way to decrease the switching current density in SOT-based spintronic devices.

  8. Ion-Exchange Reaction Of A-Site In A2Ta2O6 Pyrochlore Crystal Structure

    Directory of Open Access Journals (Sweden)

    Matsunami M.

    2015-06-01

    Full Text Available Na+ or K+ ion rechargeable battery is started to garner attention recently in Place of Li+ ion cell. It is important that A+ site ion can move in and out the positive-electrode materials. When K2Ta2O6 powder had a pyrochlore structure was only dipped into NaOH aqueous solution at room temperature, Na2Ta2O6 was obtained. K2Ta2O6 was fabricated from a tantalum sheet by a hydrothermal synthesize with KOH aqueous solution. When Na2Ta2O6 was dipped into KOH aqueous solution, K2Ta2O6 was obtained again. If KTaO3 had a perovskite structure was dipped, Ion-exchange was not observed by XRD. Because a lattice constant of pyrochlore structure of K-Ta-O system is bigger than perovskite, K+ or Na+ ion could shinny through and exchange between Ta5+ and O2− ion site in a pyrochlore structure. K+ or Na+ ion exchange of A2Ta2O6 pyrochlore had reversibility. Therefore, A2Ta2O6 had a pyrochlore structure can be expected such as Na+ ion rechargeable battery element.

  9. Using remotely sensed temperature to estimate climate response functions

    Science.gov (United States)

    Heft-Neal, Sam; Lobell, David B.; Burke, Marshall

    2017-01-01

    Temperature data are commonly used to estimate the sensitivity of many societally relevant outcomes, including crop yields, mortality, and economic output, to ongoing climate changes. In many tropical regions, however, temperature measures are often very sparse and unreliable, limiting our ability to understand climate change impacts. Here we evaluate satellite measures of near-surface temperature (Ts) as an alternative to traditional air temperatures (Ta) from weather stations, and in particular their ability to replace Ta in econometric estimation of climate response functions. We show that for maize yields in Africa and the United States, and for economic output in the United States, regressions that use Ts produce very similar results to those using Ta, despite the fact that daily correlation between the two temperature measures is often low. Moreover, for regions such as Africa with poor station coverage, we find that models with Ts outperform models with Ta, as measured by both R 2 values and out-of-sample prediction error. The results indicate that Ts can be used to study climate impacts in areas with limited station data, and should enable faster progress in assessing risks and adaptation needs in these regions.

  10. Microscopic quantum interference in excitonic condensation of Ta2NiSe5

    Science.gov (United States)

    Sugimoto, Koudai; Kaneko, Tatsuya; Ohta, Yukinori

    2016-01-01

    The microscopic quantum interference associated with excitonic condensation in Ta2NiSe5 is studied in a BCS-type mean-field approximation. We show that in ultrasonic attenuation the coherence peak appears just below the transition temperature Tc, whereas in NMR spin-lattice relaxation the rate rapidly decreases below Tc; these observations can offer a crucial experimental test for the validity of the excitonic condensation scenario in Ta2NiSe5 . We also show that excitonic condensation manifests itself in a jump of the heat capacity at Tc as well as in a softening of the elastic shear constant, in accordance with the second-order phase transition observed in Ta2NiSe5 .

  11. Hydrothermal Synthesis and Characterization of Perovskite Oxide AgTaO3

    Institute of Scientific and Technical Information of China (English)

    HE Li-jie; ZHANG Dong; FENG Shou-hua; ZOU Bo; CHEN Gang

    2012-01-01

    The perovskite-type AgTaO3 crystals were prepared by mild hydrothermal method and determined by powder X-ray diffraction.Rietveld refinement indicates that AgTaO3 crystallized in an orthorhombic system with the space group Pcmn.The lattice parameters are a-5.5822(1) nm,b=7.8522(2) nm and c=5.5347(1) nm,with α=β=γ=90.0°.The compound was characterized by scanning electron microscopy(SEM),X-ray photoelectron spectroscopy (XPS),high resolution transmission electron microscopy(HR-TEM) and UV-Vis diffuse reflectance spectrometry (UV-Vis DRS).The photocatalytic activity of AgTaO3 powder was evaluated by the degradation of Congo red under UV-light irradiation.The result shows that the titled compound has a high photocatalytic activity at room temperature and potential application in photocatalysis.

  12. Vortex motion in layered superconductors Cu0.03TaS2

    Directory of Open Access Journals (Sweden)

    Junchao Lu

    2014-06-01

    Full Text Available The vortex motion in Cu0.03TaS2 has been investigated by resistivity results with a special electrode arrangements. The vortex behaviors for H ∥ c are completely different from that for H ∥ ab. The analysis indicates that when H ∥ ab, the sharp ρ − T transition is the superconductive-normal transition while for H ∥ c, the broadened ρ − T transition is caused by the suppression of the superconducting weak link between the S-Ta-S layers. The existence of the vortex pancake in Cu0.03TaS2 is contradictory to the Clem's model, further demonstrating that the models for high temperature cuprates superconductors are not applicable to the layered transition metal dichalcogenides.

  13. Mechanochemical preparation and structural characterization of Ta-doped chlorapatite nanopowders

    Directory of Open Access Journals (Sweden)

    Bahman Nasiri-Tabrizi

    2016-12-01

    Full Text Available Nanocrystalline tantalum-doped chlorapatite (Ta-doped ClA was successfully synthesized using a facile mechanochemical method. In the absence of the dopant, milling for 3 h led to the formation of a poorly crystalline hydroxyapatite, while in its presence of the Ta dopant, Ta-doped ClA nanopowders were produced as a result of an oncoming reaction. The results indicated that lattice micro-strain, crystallite size, crystallinity level, phase percentage and hexagonal lattice constants of the substituted apatite nanopowders were dramatically affected by the doping concentration. The a-axis and unit cell volume increased with the increase in the doping concentration, owing to the ionic radius difference of Cl− and OH− ions. From the TEM observations, the doped powders consisted of nanoneedles with a mean size of 60±20 nm in length and 14±4 nm in width.

  14. Interpreting Medieval Inter-tidal Features at Weelie's Taing on Papa Westray, Orkney, NE Scotland

    Science.gov (United States)

    Pollard, Edward; Gibson, Julie; Littlewood, Mark

    2016-12-01

    Investigation of the inter-tidal heritage of the Orkney Islands is used to interpret a previously perplexing complex at Weelie's Taing on Papa Westray. The study revealed a previously unknown type of harbour since identified in several locations around Orkney. Situated in exposed environmental situations, shelter is formed by an `ayre', a type of spit that encloses a loch, and which has been used historically as a landing place or crossing of the inter-tidal zone. A complex landing area, pier, tower and ship-blockage suggest Weelie's Taing was used as a harbour. Important fishing grounds exploited since the Neolithic are nearby, and Papa Westray was the site of water-focussed religious communities. It is suggested that Weelie's Taing was in use in the medieval period when Papa Westray was less isolated than today with the presence of ecclesiastical communities and situation on the Orkney-Shetland route.

  15. Choosing an SAT with SAnTA: A Recommender System for Informal Workplace Learning

    Directory of Open Access Journals (Sweden)

    Frank Linton

    2015-10-01

    Full Text Available Current intelligence community analytic standards encourage the use of structured analytic techniques; these are taught in training programs and supported by analytic tradecraft cells. Yet resources are scarce, timely personalized help is not available to all when it is most needed, and conditions for the improper selection and misapplication of these techniques prevail. The Structured Analytic Technique Advisor (SAnTA is an electronic interactive job aid that recommends structured analytic techniques to analysts, based on the current state of their analysis and on the synthesized expertise of tradecraft staff. SAnTA is undergoing formative evaluation and iterative development. When released, SAnTA will provide individualized support to a large number of analysts every day.

  16. Blistering and cracking of LiTaO{sub 3} single crystal under helium ion implantation

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Changdong; Lu, Fei; Ma, Yujie [Shandong University, School of Information Science and Engineering, Jinan, Shandong (China)

    2014-11-29

    Blistering and cracking in LiTaO{sub 3} surface are investigated after 200-keV helium ion implantation and subsequent post-implantation annealing. Rutherford backscattering/channeling is used to examine the lattice damage caused by ion implantation. Blistering is observed through optical microscopy in a dynamic heating process. Atomic force microscopy and scanning electron microscopy measurements are used to detect the LiTaO{sub 3} surface morphology. Experimental results show that blistering and flaking are dependent on implantation fluence, beam current, and also annealing temperature. We speculate that the surface cracking of He{sup +}-implanted LiTaO{sub 3} results from the implantation-induced stress and compression. (orig.)

  17. Large magnetoresistance in compensated semimetals TaAs2 and NbAs2

    Science.gov (United States)

    Yuan, Zhujun; Lu, Hong; Liu, Yongjie; Wang, Junfeng; Jia, Shuang

    2016-05-01

    We report large magnetoresistance (MR) at low temperatures in single-crystalline nonmagnetic compounds TaAs2 and NbAs2. Both compounds exhibit parabolic-field-dependent MR larger than 5 ×103 in a magnetic field of 9 Tesla at 2 K. The MR starts to deviate from parabolic dependence above 10 T and intends to be saturated in 45 T for TaAs2 at 4.2 K. The Hall resistance measurements and band structure calculations reveal their compensated semimetal characteristics. Their large MR at low temperatures is ascribed to an effect for compensation of electrons and holes with large mobilities. After discussing the MR for different samples of TaAs2 and other semimetals, we found that the magnitudes of MR are strongly dependent on the samples' quality for different compounds.

  18. Genome sequence of the clover-nodulating Rhizobium leguminosarum bv. trifolii strain TA1.

    Science.gov (United States)

    Reeve, Wayne; Tian, Rui; De Meyer, Sofie; Melino, Vanessa; Terpolilli, Jason; Ardley, Julie; Tiwari, Ravi; Howieson, John; Yates, Ronald; O'Hara, Graham; Ninawi, Mohamed; Teshima, Hazuki; Bruce, David; Detter, Chris; Tapia, Roxanne; Han, Cliff; Wei, Chia-Lin; Huntemann, Marcel; Han, James; Chen, I-Min; Mavromatis, Konstantinos; Markowitz, Victor; Ivanova, Natalia; Ovchinnikova, Galina; Pagani, Ioanna; Pati, Amrita; Goodwin, Lynne; Pitluck, Sam; Woyke, Tanja; Kyrpides, Nikos

    2013-12-20

    Rhizobium leguminosarum bv. trifolii strain TA1 is an aerobic, motile, Gram-negative, non-spore-forming rod that is an effective nitrogen fixing microsymbiont on the perennial clovers originating from Europe and the Mediterranean basin. TA1 however is ineffective with many annual and perennial clovers originating from Africa and America. Here we describe the features of R. leguminosarum bv. trifolii strain TA1, together with genome sequence information and annotation. The 8,618,824 bp high-quality-draft genome is arranged in a 6 scaffold of 32 contigs, contains 8,493 protein-coding genes and 83 RNA-only encoding genes, and is one of 20 rhizobial genomes sequenced as part of the DOE Joint Genome Institute 2010 Community Sequencing Program.

  19. Ta2O5 nanowires: a novel synthetic method and their solar energy utilization.

    Science.gov (United States)

    Lü, Xujie; Ding, Shangjun; Lin, Tianquan; Mou, Xinliang; Hong, Zhanglian; Huang, Fuqiang

    2012-01-14

    Single-crystalline uniform Ta(2)O(5) nanowires are prepared by a novel synthetic route. The formation of the nanowires involves an oriented attachment process caused by the reduction of surface energy. The nanowires are successfully applied to photocatalytic H(2) evolution, contaminant degradation, and dye-sensitized solar cells (DSCs). The Ta(2)O(5)-based DSCs reveal a significant photovoltaic response, which has not been reported. As a photocatalyst, the Ta(2)O(5) nanowires possess high H(2) evolution efficiency under Xe lamp irradiation, nearly 27-fold higher than the commercial powders. A better performance of photocatalytic contaminant degradation is also observed. Such improvements are ascribed to better charge transport ability for the single-crystalline wire and a higher potential energy of the conduction band. This new synthetic approach using a water-soluble precursor provides a versatile way to prepare nanostructured metal oxides.

  20. Search for the decay of nature's rarest isotope $^{\\rm {180m}}$Ta

    CERN Document Server

    Lehnert, Björn; Lutter, Guillaume; Zuber, Kai

    2016-01-01

    $^{\\rm {180m}}$Ta is the rarest naturally occurring quasi-stable isotope and the longest lived metastable state which is known. Its possible decay via the $\\beta^-$ or the electron capture channel has never been observed. This article presents a search for the decay of $^{\\rm {180m}}$Ta with an ultra low background Sandwich HPGe gamma spectrometry setup in the HADES underground laboratory. No signal is observed and improved lower partial half-life limits are set with a Bayesian analysis to $5.8\\cdot10^{16}$ yr for the $\\beta^-$ channel and $2.0\\cdot10^{17}$ yr for the electron capture channel (90% credibility). The total half-life of $^{\\rm {180m}}$Ta is longer than $4.5\\cdot10^{16}$ yr. This is more than a factor of two improvement compared to previous searches.

  1. Microstructure, mechanical behavior and biocompatibility of powder metallurgy Nb-Ti-Ta alloys as biomedical material.

    Science.gov (United States)

    Liu, Jue; Chang, Lin; Liu, Hairong; Li, Yongsheng; Yang, Hailin; Ruan, Jianming

    2017-02-01

    Microstructures, mechanical properties, apatite-forming ability and in vitro experiments were studied for Nb-25Ti-xTa (x=10, 15, 20, 25, 35at.%) alloys fabricated by powder metallurgy. It is confirmed that the alloys could achieve a relative density over 80%. Meanwhile, the increase in Ta content enhances the tensile strength, elastic modulus and hardness of the as-sintered alloys. When increasing the sintering temperatures, the microstructure became more homogeneous for β phase, resulting in a decrease in the modulus and strength. Moreover, the alloys showed a good biocompatibility due to the absence of cytotoxic elements, and were suitable for apatite formation and cell adhesion. In conclusion, Nb-25Ti-xTa alloys are potentially useful in biomedical applications with their mechanical and biological properties being evaluated in this work. Copyright © 2016 Elsevier B.V. All rights reserved.

  2. Fishing TaSC Interacting Protein in Wheat Using Split Ubiquitin Yeast Two Hybrid System%利用分裂泛素酵母双杂交技术钓取小麦TaSC互作蛋白质

    Institute of Scientific and Technical Information of China (English)

    蔺芳芳; 杨旭; 武小翠; 刘晓梅; 葛荣朝; 赵宝存

    2013-01-01

      TaSC (Triticum asetivum L. salt-tolerance related gene, GenBank 登录号为 AY956330)是从小麦耐盐突变体RH8706-49中克隆的高盐诱导表达的耐盐相关基因.以该基因编码的蛋白质TaSC为诱饵,运用分裂泛素酵母双杂交技术从小麦 cDNA 表达文库中钓取互作蛋白质,筛选到一个编码小麦未知功能蛋白质的基因(GenBank 登录号为AK336035),命名为TaSCIP1(TaSC interaction protein 1).双分子荧光互补(BiFC)实验证实TaSCIP1与TaSC存在互作.该互作蛋白的分离有利于进一步研究TaSC基因的耐盐机制.%The TaSC (Triticum asetivum L. salt-tolerance related gene, GenBank accession number AY956330) has been cloned from wheat salt tolerant mutant RH 8706-49, which is induced by high salinity. To fish interacting proteins of this gene, we used TaSC protein as bait to hybrid with the wheat cDNA expression library using the split ubiquitin yeast two hybrid system in this experiment. A novel wheat gene (GenBank accession number AK336035) encoding a protein with unknown function was isolated, which was designated TaSCIP1 (TaSC interaction protein 1). Bimolecular fluorescence complementation (BiFC) experiment con-firmed the interaction between proteins TaSCIP1 and TaSC. The separation of TaSC-interacting protein is beneficial to disclose the mechanism of salt tolerance gene TaSC.

  3. Deposition and characterization of TaAIN thin films by reactive magnetron sputtering; Deposicao e caracterizacao de filmes finos de TaAIN depositados por magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, G.B.; Fernandez, D.R.; Fontes Junior, A.S.; Felix, L.C.; Tentardini, E.K. [Universidade Federal de Sergipe (UFS), Sao Cristovao, SE (Brazil). Departamento de Ciencia e Engenharia de Materiais; Hubler, R. [Pontificia Universidade Catolica do Rio Grande do Sul (PUC-RS), RS (Brazil); Silva Junior, A.H. da, E-mail: brito-g@hotmail.com [Universidade Federal do Rio Grande do Sul (UFRGS), RS (Brazil)

    2016-07-01

    Phase stability, oxidation resistance and great mechanical properties are the main objectives when synthesizing protective coatings. The tantalum nitride (TaN) has aroused interest because of its high temperature stability, chemical inertness and thermal conductivity. However, it has a low hardness value when compared to other coatings. Researches has shown that one way to improvements in the properties of a thin film is by adding other elements in the deposition process. Therefore, the objective of this study was to deposit thin films of TaAlN by magnetron sputtering, changing the aluminum concentration of 2, 5, 7, to 14%. Then the coatings were characterized by EDS, RBS, GIXRD and nanohardness. In this study was found that the aluminum deposited did not change the oxidation resistance of the coating, and the highest value of hardness was 28 GPa for the sample with 14 at.%. (author)

  4. Impact of total ionizing dose irradiation on Pt/SrBi{sub 2}Ta{sub 2}O{sub 9}/HfTaO/Si memory capacitors

    Energy Technology Data Exchange (ETDEWEB)

    Yan, S. A.; Tang, M. H., E-mail: mhtang@xtu.edu.cn, E-mail: lizheng@xtu.edu.cn; Xiao, Y. G.; Zhang, W. L. [School of Materials Science and Engineering, Xiangtan University, Xiangtan 411105 (China); Hunan Provincial National Defense Key Laboratory of Key Film Materials and Application for Equipments, Xiangtan University, Xiangtan 411105 (China); Hunan Provincial Key Laboratory of Thin Film Materials and Devices, Xiangtan University, Xiangtan 411105 (China); Zhao, W.; Guo, H. X. [Northwest Institute of Nuclear Technology, Xi' an, Shanxi 710024 (China); Xiong, Y. [The School of Mathematics and Computational Science, Xiangtan University, Xiangtan, Hunan 411105 (China); Li, Z., E-mail: mhtang@xtu.edu.cn, E-mail: lizheng@xtu.edu.cn; Ding, H.; Chen, J. W.; Zhou, Y. C. [School of Materials Science and Engineering, Xiangtan University, Xiangtan 411105 (China)

    2015-01-05

    In this work, metal-ferroelectric-insulator-semiconductor (MFIS) structure capacitors with SrBi{sub 2}Ta{sub 2}O{sub 9} (300 nm) as ferroelectric thin film and HfTaO (6 nm, 8 nm, 10 nm, and 12 nm) as insulating buffer layer were proposed and investigated. The prepared capacitors were fabricated and characterized before radiation and then subjected to {sup 60}Co gamma irradiation in steps of two dose levels. Significant irradiation-induced degradation of the electrical characteristics was observed. The radiation experimental results indicated that stability and reliability of as-fabricated MFIS capacitors for nonvolatile memory applications could become uncontrollable under strong irradiation dose and/or long irradiation time.

  5. [The mutagenic action of radioactive contaminants of feed and food products on strains TA98 and TA100 of Salmonella typhimurium].

    Science.gov (United States)

    Matseliukh, B P; Lavrinchuk, V Ia; Bambura, O I; Kopiĭko, O P

    1996-01-01

    Radionuclide-polluted slices of beef (2775 Bq/kg), pork (274.8 Bq/kg), potato (159.0-444.0 Bq/kg), carrot, garden beet, kidney bean and sorrel (44.5-460.0 Bq/kg) have been studied for their mutagenic effect on the tester strains TA98 and TA100 of Salmonella typhimurium and this index as a rule correlates with the level of the slices pollution. On the other hand the slices of cabbage and samples of rye and wheat (46.0-460.0 Bq/kg) as well as fish (2314.0 Bq/kg) had no mutagenic effect on these strains. The samples of milk (230.0-581.5 Bq/1) also did not evoke the increase of mutagenesis level while high concentrations of these preparations (20 mg/ml, and above) manifested toxic effect on the mentioned strains.

  6. Mechanical Failure of Thin Ta and Cu/Ta Layers on Polyimide Substrates: A Synchrotron-Based Technique for In Situ Characterization

    Science.gov (United States)

    Frank, Stephan; Handge, Ulrich A.; Olliges, Sven; Spolenak, Ralph

    2009-06-01

    In situ synchrotron radiation diffraction and confocal light microscopy is used to study fragmentation and buckling of thin brittle Ta layers with thicknesses of 50 nm, 100 nm and 200 nm on polyimide substrates. Synchrotron-based stress measurements confirm that cracking leads to relaxation of tensile stress. Simultaneously, compressive stress arises in transverse direction, which finally leads to buckling. This behavior can be explained quantitatively by a two-dimensional shear lag model. It is well established that the properties of the coating-substrate interface determine the processes of coating fragmentation and delamination. A possible approach for influencing and controlling these processes is given by the incorporation of a ductile interlayer. It can be observed that the presence of Cu interlayers with thicknesses of 5 nm, 20 nm and 50 nm reduces the fracture strength of brittle Ta coatings on polyimide substrates, whereas the resistance to buckling is increased significantly.

  7. 3D Ta/TaO x /TiO2/Ti synaptic array and linearity tuning of weight update for hardware neural network applications

    Science.gov (United States)

    Wang, I.-Ting; Chang, Chih-Cheng; Chiu, Li-Wen; Chou, Teyuh; Hou, Tuo-Hung

    2016-09-01

    The implementation of highly anticipated hardware neural networks (HNNs) hinges largely on the successful development of a low-power, high-density, and reliable analog electronic synaptic array. In this study, we demonstrate a two-layer Ta/TaO x /TiO2/Ti cross-point synaptic array that emulates the high-density three-dimensional network architecture of human brains. Excellent uniformity and reproducibility among intralayer and interlayer cells were realized. Moreover, at least 50 analog synaptic weight states could be precisely controlled with minimal drifting during a cycling endurance test of 5000 training pulses at an operating voltage of 3 V. We also propose a new state-independent bipolar-pulse-training scheme to improve the linearity of weight updates. The improved linearity considerably enhances the fault tolerance of HNNs, thus improving the training accuracy.

  8. Intersectional Gene Expression in Zebrafish Using the Split KalTA4 System.

    Science.gov (United States)

    Almeida, Rafael Gois; Lyons, David Anthony

    2015-12-01

    In this study, we describe the adaptation of the split Gal4 system for zebrafish. The Gal4-UAS system is widely used for expression of genes-of-interest by crossing driver lines expressing the transcription factor Gal4 (under the control of the promoter of interest) with reporter lines where upstream activating sequence (UAS) repeats (recognized by Gal4) drive expression of the genes-of-interest. In the Split Gal4 system, hemi-drivers separately encode the DNA-binding domain (DBD) and the activation domain (AD) of Gal4. When encoded under two different promoters, only those cells in the intersection of the promoters' expression pattern and in which both promoters are active reconstitute a functional Gal4 and activate expression from a UAS-driven transgene. We split the zebrafish-optimized version of Gal4, KalTA4, and generated a hemi-driver encoding the KalTA4 DBD and a hemi-driver encoding KalTA4's AD. We show that split KalTA4 domains can assemble in vivo and transactivate a UAS reporter transgene and that each hemi-driver alone cannot transactivate the reporter. Also, transactivation can happen in several cell types, with similar efficiency to intact KalTA4. Finally, in transient mosaic expression assays, we show that when hemi-drivers are preceded by two distinct promoters, they restrict the expression of an UAS-driven reporter from a broader pattern (sox10) to its constituent smaller neuronal pattern. The Split KalTA4 system should be useful for expression of genes-of-interest in an intersectional manner, allowing for more refined manipulations of cell populations in zebrafish.

  9. Interleukin-8 gene polymorphism –251T>A contributes to Alzheimer's disease susceptibility

    Science.gov (United States)

    Qin, Biyong; Li, Li; Wang, Shanshan; Wu, Jun; Huang, Yulan; Zhou, Ping; Bai, Jiao; Zheng, Yan

    2016-01-01

    Abstract Background: Published association studies have investigated the correlation between interleukin-8 (IL-8) gene polymorphism –251T>A and susceptibility to Alzheimer's disease (AD); however, the results are conflicting. Thus, we conducted the meta-analysis to reassess the effect of IL-8 gene –251T>A variant on the risk of AD. Methods: Relevant studies regarding this association were electronically searched and identified from the PubMed, Embase, Cochrane Library, China National Knowledge Infrastructure, and the Chinese Biomedicine Database. The odds ratios (ORs) with the corresponding 95% confidence intervals (95% CIs) were pooled to calculate the strength of this association. Results: Nine studies with a total of 1406 cases and 2152 controls were included in the meta-analysis. Overall, a significant association of IL-8 gene –251T>A polymorphism with increased risk of AD was observed in several genetic models (allele, A vs T: OR=1.32, 95%CI=1.16-1.50; homozygous, AA vs TT: OR=1.70, 95%CI=1.21–2.21; heterozygous, TA vs TT: OR=1.37, 95%CI=1.12–1.69; recessive, AA vs TA+TT: OR=1.40, 95%CI=1.12–1.75). Similarly, such association was also revealed both in Asian and European populations in the subgroup analysis by ethnicity. Conclusion: The current study suggested that IL-8 gene polymorphism –251T>A may contribute to the susceptibility to AD. PMID:27684880

  10. 新一代数字集群通信系统--GoTa%GoTa-A New Generation Digital Trunking Communication System

    Institute of Scientific and Technical Information of China (English)

    曾少华

    2004-01-01

    文章介绍了中兴通讯自主开发的数字集群通信系统--GoTa,给出了系统组网结构、业务功能和业务定位,指出由于有巨大的市场需求因而GoTa系统应用前景广阔.

  11. Parameter Estimation

    DEFF Research Database (Denmark)

    2011-01-01

    of optimisation techniques coupled with dynamic solution of the underlying model. Linear and nonlinear approaches to parameter estimation are investigated. There is also the application of maximum likelihood principles in the estimation of parameters, as well as the use of orthogonal collocation to generate a set......In this chapter the importance of parameter estimation in model development is illustrated through various applications related to reaction systems. In particular, rate constants in a reaction system are obtained through parameter estimation methods. These approaches often require the application...... of algebraic equations as the basis for parameter estimation.These approaches are illustrated using estimations of kinetic constants from reaction system models....

  12. Coherence Factors and Quantum Interferences in Excitonic Condensation of Ta2NiSe5

    Science.gov (United States)

    Sugimoto, Koudai; Kaneko, Tatsuya; Ohta, Yukinori

    2017-04-01

    In order to elucidate whether Ta2NiSe5 is in an excitonic condensation state or not, we study macroscopic quantum interferences in ultrasonic attenuation rate and nuclear magnetic resonance relaxation rate. Using the three-chain model describing the excitonic condensation of Ta2NiSe5, we demonstrate analytically that the ultrasonic attenuation rate shows a characteristic peak just below the transition temperature of the excitonic condensation, while the nuclear magnetic resonance relaxation rate shows a rapid drop. In particular, we find that the constructive interference originates from the hybridization between the conduction and valence bands induced by an external field.

  13. Excitonic Bose-Einstein condensation in Ta2NiSe5 above room temperature

    Science.gov (United States)

    Seki, K.; Wakisaka, Y.; Kaneko, T.; Toriyama, T.; Konishi, T.; Sudayama, T.; Saini, N. L.; Arita, M.; Namatame, H.; Taniguchi, M.; Katayama, N.; Nohara, M.; Takagi, H.; Mizokawa, T.; Ohta, Y.

    2014-10-01

    We show that finite temperature variational cluster approximation (VCA) calculations on an extended Falicov-Kimball model can reproduce angle-resolved photoemission spectroscopy (ARPES) results on Ta2NiSe5 across a semiconductor-to-semiconductor structural phase transition at 325 K. We demonstrate that the characteristic temperature dependence of the flat-top valence band observed by ARPES is reproduced by the VCA calculation on the realistic model for an excitonic insulator only when the strong excitonic fluctuation is taken into account. The present calculations indicate that Ta2NiSe5 falls in the Bose-Einstein condensation regime of the excitonic insulator state.

  14. Photoelectron Spectroscopy Study of [Ta2B6]-: a Hexagonal Bipyramdial Cluster

    Science.gov (United States)

    Jian, Tian; Li, Weili; Romanescu, Constantin; Wang, Lai-Sheng

    2014-06-01

    It has been a long-sought goal in cluster science to discover stable atomic clusters as building blocks for cluster-assembled nanomaterials, as exemplified by the fullerenes and their subsequent bulk syntheses.[1,2] Clusters have also been considered as models to understand bulk properties, providing a bridge between molecular and solid-state chemistry.[3] Herein we report a joint photoelectron spectroscopy and theoretical study on the [Ta2B6]- and [Ta2B6] clusters.[4] The photoelectron spectrum of [Ta2B6]- displays a simple spectral pattern and a large HOMO-LUMO gap, suggesting its high symmetry. Theoretical calculations show that both the neutral and anion are D6h pyramidal. The chemical bonding analyses for [Ta2B6] revealed the nature of the B6 and Ta interactions and uncovered strong covalent bonding between B6 and Ta. The D6h-[TaB6Ta] gaseous cluster is reminiscent of the structural pattern in the ReB6X6Re core in the [(Cp*Re)2B6H4Cl2] and the TiB6Ti motif in the newly synthesized Ti7Rh4Ir2B8 solid-state compound.[5,6] The current work provides an intrinsic link between a gaseous cluster and motifs for solid materials. Continued investigations of the transition-metal boron clusters may lead to the discovery of new structural motifs involving pure boron clusters for the design of novel boride materials. Reference [1] H.W. Kroto, J. R. Heath, S. C. OBrien, R. F. Curl, R. E. Smalley, Nature 1985, 318, 162 - 163. [2] W. Krtschmer, L. D. Lamb, K. Fostiropoulos, D. R. Huffman, Nature 1990, 347, 354 - 358. [3] T. P. Fehlner, J.-F. Halet, J.-Y. Saillard, Molecular Clusters: A Bridge to Solid-State Chemitry, Cambridge University Press, UK, 2007. [4] W. L. Li, L. Xie, T. Jian, C. Romanescu, X. Huang, L.-S. Wang, Angew. Chem. Int. Ed. 2014, 126, 1312 - 1316. [5] B. Le Guennic, H. Jiao, S. Kahlal, J.-Y. Saillard, J.-F. Halet, S. Ghosh, M. Shang, A. M. Beatty, A. L. Rheingold, T. P. Fehlner, J. Am. Chem. Soc. 2004, 126, 3203 - 3217. [6] B. P. T. Fokwa, M. Hermus, Angew

  15. Fatigue modification of TA15 titanium alloy weldments by an ultrasonic impact treatment

    DEFF Research Database (Denmark)

    Gao, Yukui; Zhong, Zheng; Zhang, Xiaodan;

    2014-01-01

    The welded components of TA15 titanium alloy were ultrasonically impact treated. The fatigue lives were investigated under the same test conditions. The fatigue strength was determined by stair-step method and the residual stresses were analyzed by an X-ray diffraction stress tester. The results...... show that the fatigue properties of TA15 titanium alloy welded components are sensitive to the surface treatment and ultrasonic impacting can prolong the fatigue lives. The effect of fatigue strength improvement mainly depends on compressive residual stresses and grain refinement....

  16. Observation of inhomogeneity in congruent LiTaO3 crystal

    Institute of Scientific and Technical Information of China (English)

    X.B.Hu; H.D.Jiang; H.Liu; S.S.Jiang; Q.Li; J.Y.Wang; C.Q.Zhang; B.Ten

    2001-01-01

    The inhomogeneity in a congrunet LiTaO3 crystal has been observed by transmission synchrotron topography.Many extraordinary regions exist in congruent LiTaO3 crystal and they often show diffraction intensity different from that of ordinary regions in synchrotron topographs.Differential thermal analysis indiates that the Curie temperature of the extraordinary region is lower than that of ordinary region,and the extraordinary region is really a high defect density region.The diffraction contrast of the extraordinary region in synchrotron topographs is explained qualitatively by a calculation at the selected wavelength.2001 Published by Elsevier Science B.V.

  17. Low Dimensional K(Nb, Ta)O3 Thin Film Structures

    Science.gov (United States)

    2007-11-02

    solid state synthesis . The starting materials were K2CO3, Ta2O5, Nb2O5, and TiO2. The powders were reacted in air at 900˚C for 4 hrs, reground...KTa0.63Nb0.37O3 targets were made by solid state synthesis . The starting materials were K2CO3, Ta2O5, and Nb2O5. The powders were reacted in air at 900˚C

  18. El juego de la parodia en la escritura de Anne F. Garréta

    Directory of Open Access Journals (Sweden)

    Montserrat Cots Vicente

    2013-04-01

    Full Text Available The objective of this article is to study the dimension of parody in the work of Anne Garréta in light of the theories of Authier-Revuz regarding the essential het-erogeneity of discourse. We show how Garréta’s parody makes allusion to other sources without specifying them and systematically effaces borders between her own discourse and that of others. We argue that through this personal (intertextual montage Garréta unveils a social, literary and linguistic critique to the informed reader.

  19. Spin Glass Behavior in the Dy3-xYxTaO7 System

    OpenAIRE

    Gomez-Garcia, J. Francisco; Escudero, Roberto; Tavizon, Gustavo

    2014-01-01

    Several x-compositions of the polycrystalline Dy3-xYxTaO7 system, crystallizing in the weberite-type structure, were synthesized and structurally characterized using Rietveld refinements based on X-ray diffraction data. In previous magnetic characterization of Dy3TaO7 (x = 0), with the same crystal structure, an antiferromagnetic transition at T = 2.3 K has been assigned to this compound. On the basis of DC and AC magnetic susceptibilities analyses, we show in this work that all compounds in ...

  20. Electronic structure of Mn{sub 0.25}TaS{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Debnath, Saikat; Mahadevan, Priya, E-mail: priya@bose.res.in

    2016-04-15

    The electronic structure of Mn{sub 0.25}TaS{sub 2} has been studied with ab-initio electronic structure calculations. Various magnetic configurations have been considered for the ordering of the spins on Mn. Despite the typical separation of the Mn atoms being ∼6 Å, one finds that the ferromagnetic configuration is strongly stabilized. This is traced to a pathway between Mn d{sub z}{sup 2} orbitals and Ta d{sub z}{sup 2} orbitals which results in a strong exchange coupling of the Mn spins in the c direction.