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Sample records for airborne bismuth contributions

  1. Contribution of traffic emissions to indoor airborne VOCs

    SciTech Connect

    Otson, R.; Williams, D.T.; Fellin, P.

    1998-12-31

    The contribution of nearby vehicle traffic to indoor airborne volatile organic compound levels and to personal exposures was examined to determine the importance of this source. Indoor and outdoor levels of selected VOCs, aldehydes, ketones, and ethanol were measured at 10 homes in Toronto, on sidewalks near the traffic source, indoors and in the backyards or balconies of apartments (outdoors). Concurrently, air exchange rates were measured at each home with a perfluorocarbon tracer method. All the residences were within 1 km of urban intersections with traffic counts of more than 20,000 vehicles per day. Average concentrations of hexane, 1,3-butadiene, toluene, benzene and propionaldehyde decreased in the order: street level > indoor > outdoor. These compounds occur in vehicle emissions, and the contribution of outdoor to indoor concentrations ranged from 24 to 88 % suggesting that traffic emissions contributed to indoor pollutant level through the process of air exchange. For other compounds different trends were observed. Indoors concentrations were greater than outdoors for ethylacetate, tetrachlorethane, pinene, limonene, 1,4-dichlorobenzene, naphthalene, formaldehyde, acetaldehyde and ethanol, for example. These compounds are common in consumer products, and the contribution of outdoor to indoor concentrations ranged from 2 to 44%. The differences in street and backyard (outdoor) concentrations for some compounds were large due to the presence of nearby vehicles at street level sampling sites, indicating that the impact of traffic on human exposures (pedestrians on sidewalks and occupants of vehicles) is potentially large, compared to the impact of general background urban air pollutants.

  2. The NASA Airborne Astronomy Program: A perspective on its contributions to science, technology, and education

    NASA Technical Reports Server (NTRS)

    Larson, Harold P.

    1995-01-01

    The scientific, educational, and instrumental contributions from NASA's airborne observatories are deduced from the program's publication record (789 citations, excluding abstracts, involving 580 authors at 128 institutions in the United States and abroad between 1967-1990).

  3. Total contribution of airborne lead to blood lead.

    PubMed Central

    Manton, W I

    1985-01-01

    A nine year study of blood lead concentrations and isotope ratios carried out on a married couple shows that pulmonary deposition cannot account for all the airborne lead in blood; that lead from bone may comprise 70% of blood lead; and that during pregnancy blood lead may double due to mobilisation of lead from bone. PMID:3970881

  4. Bismuth Subsalicylate

    MedlinePlus

    Pink Bismuth® ... Bismuth subsalicylate is used to treat diarrhea, heartburn, and upset stomach in adults and children 12 years of age and older. Bismuth subsalicylate is in a class of medications called ...

  5. Effect of land uses and wind direction on the contribution of local sources to airborne pollen.

    PubMed

    Rojo, Jesús; Rapp, Ana; Lara, Beatriz; Fernández-González, Federico; Pérez-Badia, Rosa

    2015-12-15

    The interpretation of airborne pollen levels in cities based on the contribution of the surrounding flora and vegetation is a useful tool to estimate airborne allergen concentrations and, consequently, to determine the allergy risk for local residents. This study examined the pollen spectrum in a city in central Spain (Guadalajara) and analysed the vegetation landscape and land uses within a radius of 20km in an attempt to identify and locate the origin of airborne pollen and to determine the effect of meteorological variables on pollen emission and dispersal. The results showed that local wind direction was largely responsible for changes in the concentrations of different airborne pollen types. The land uses contributing most to airborne pollen counts were urban green spaces, though only 0.1% of the total surface area studied, and broadleaved forest which covered 5% of the study area. These two types of land use together accounted for 70% of the airborne pollen. Crops, scrubland and pastureland, though covering 80% of the total surface area, contributed only 18.6% to the total pollen count, and this contribution mainly consisted of pollen from Olea and herbaceous plants, including Poaceae, Urticaceae and Chenopodiaceae-Amaranthaceae. Pollen from ornamental species were mainly associated with easterly (Platanus), southerly (Cupressaceae) and westerly (Cupressaceae and Platanus) winds from the areas where the city's largest parks and gardens are located. Quercus pollen was mostly transported by winds blowing in from holm-oak stands on the eastern edge of the city. The highest Populus pollen counts were associated with easterly and westerly winds blowing in from areas containing rivers and streams. The airborne pollen counts generally rose with increasing temperature, solar radiation and hours of sunlight, all of which favour pollen release. In contrast, pollen counts declined with increased relative humidity and rainfall, which hinder airborne pollen transport

  6. The NASA airborne astronomy program - A perspective on its contributions to science, technology, and education

    NASA Technical Reports Server (NTRS)

    Larson, Harold P.

    1992-01-01

    The publication records from NASA's airborne observatories are examined to evaluate the contribution of the airborne astronomy program to technological development and scientific/educational progress. The breadth and continuity of program is detailed with reference to its publication history, discipline representation, literature citations, and to the ability of such a program to address nonrecurring and unexpected astronomical phenomena. Community involvement in the airborne-observation program is described in terms of the number of participants, institutional affiliation, and geographic distribution. The program utilizes instruments including heterodyne and grating spectrometers, high-speed photometers, and Fabry-Perot spectrometers with wide total spectral ranges, resolutions, and numbers of channels. The potential of the program for both astronomical training and further scientific, theoretical, and applied development is underscored.

  7. Contribution of the source velocity to the scattering of electromagnetic fields caused by airborne magnetic dipoles

    NASA Astrophysics Data System (ADS)

    Emanoel Starteri Sampaio, Edson

    2014-08-01

    The velocity of controlled airborne sources of electromagnetic geophysical surveys plays an additional role in the scattering of the fields by the earth. Therefore, it is necessary to investigate its contribution in the space and time variation of secondary electromagnetic fields. The model of a vertical magnetic dipole moving at a constant speed along a horizontal line in the air and above a homogeneous conductive half-space constitutes a first approach to stress the kinematic aspect and determine the difference between the fields due to an airborne and a static source. The magnetic moment of the source is equal to 104 A m2, its height is 120 m, and the horizontal and vertical separations between it and the receiver are, respectively, equal to 100 and 50 m: these values of the model are typical of towed-bird airborne TDEM surveys. We employed four values for the common velocities of source and receiver (0, 60, 80, and 100 m s-1), four values of the conductivity of the half-space (0.5, 0.1, 0.05, and 0.01 S m-1), and two causal source currents (box with periods of 80 and 10 ms and periodic with frequency values of 12.5 and 100 Hz). The results demonstrate that the relative velocity between source and medium yields a measurable variation compared to the static condition. Therefore, it must be taken into consideration by compensating the discrepancy in measured data employing the respective theoretical result. The results also show that it is necessary to adjust the concepts of time and frequency domain for electromagnetic measurements with traveling sources.

  8. Valley polarization in bismuth

    NASA Astrophysics Data System (ADS)

    Fauque, Benoit

    2013-03-01

    The electronic structure of certain crystal lattices can contain multiple degenerate valleys for their charge carriers to occupy. The principal challenge in the development of valleytronics is to lift the valley degeneracy of charge carriers in a controlled way. In bulk semi-metallic bismuth, the Fermi surface includes three cigar-shaped electron valleys lying almost perpendicular to the high symmetry axis known as the trigonal axis. The in-plane mass anisotropy of each valley exceeds 200 as a consequence of Dirac dispersion, which drastically reduces the effective mass along two out of the three orientations. According to our recent study of angle-dependent magnetoresistance in bismuth, a flow of Dirac electrons along the trigonal axis is extremely sensitive to the orientation of in-plane magnetic field. Thus, a rotatable magnetic field can be used as a valley valve to tune the contribution of each valley to the total conductivity. As a consequence of a unique combination of high mobility and extreme mass anisotropy in bismuth, the effect is visible even at room temperature in a magnetic field of 1 T. Thus, a modest magnetic field can be used as a valley valve in bismuth. The results of our recent investigation of angle-dependent magnetoresistance in other semi-metals and doped semiconductors suggest that a rotating magnetic field can behave as a valley valve in a multi-valley system with sizeable mass anisotropy.

  9. Geogenic Sources Strongly Contribute to the Mackenzie River Delta's Methane Emissions Derived From Airborne Flux Data

    NASA Astrophysics Data System (ADS)

    Kohnert, K.; Serafimovich, A.; Metzger, S.; Hartmann, J.; Sachs, T.

    2015-12-01

    Arctic permafrost-associated wetlands and thawing permafrost emit the greenhouse gas methane (CH4), either as a product of recent microbial activity in the active layer or taliks, or from deeper geogenic sources where pathways through the permafrost exist. Current emission estimates vary strongly between different models and there is still disagreement between bottom-up estimates from local field studies and top-down estimates from atmospheric measurements. We use airborne flux data from two campaigns in the Mackenzie River Delta, Canada, in July 2012 and 2013 to directly quantify permafrost CH4 emissions on the regional scale, to analyse the regional pattern of CH4 fluxes and to estimate the contribution of geogenic emissions to the overall CH4 budget of the delta. CH4 fluxes were calculated with a time-frequency resolved version of the eddy covariance technique, resulting in a gridded 100 m x 100 m resolution flux map within the footprints of the flight tracks. We distinguish geogenic gas seeps from biogenic sources by their strength and show that they contribute strongly to the annual CH4 budget of the delta. Our study provides the first estimate of annual CH4 release from the Mackenzie River Delta and the adjacent coastal plain. We show that one percent of the covered area contains the strongest geogenic seeps which contribute disproportionately to the annual emission estimate. Our results show that geogenic CH4 emissions might need more attention, especially in areas where permafrost is vulnerable to thawing sufficiently to create pathways for geogenic gas migration. The presented map can be used as a baseline for future CH4 flux studies in the Mackenzie River Delta.

  10. Crop harvest in Denmark and Central Europe contributes to the local load of airborne Alternaria spore concentrations in Copenhagen

    NASA Astrophysics Data System (ADS)

    Skjøth, C. A.; Sommer, J.; Frederiksen, L.; Gosewinkel Karlson, U.

    2012-11-01

    This study examines the hypothesis that Danish agricultural areas are the main source of airborne Alternaria spores in Copenhagen, Denmark. We suggest that the contribution to the overall load is mainly local or regional, but with intermittent long distance transport (LDT) from more remote agricultural areas. This hypothesis is supported by investigating a 10 yr bi-hourly record of Alternaria spores in the air from Copenhagen. This record shows 232 clinically relevant episodes (daily average spore concentration above 100 m-3) with a distinct daily profile. The data analysis also revealed potential LDT episodes almost every year. A source map and analysis of atmospheric transport suggest that LDT always originates from the main agricultural areas in Central Europe. A dedicated emission study in cereal crops under harvest during 2010 also supports our hypothesis. The emission study showed that although the fields had been treated against fungal infections, harvesting still produced large amounts of airborne fungal spores. It is likely that such harvesting periods can cause clinically relevant levels of fungal spores in the atmosphere. Our findings suggest that crop harvest in Central Europe causes episodes of high airborne Alternaria spore concentrations in Copenhagen as well as other urban areas in this region. It is likely that such episodes could be simulated using atmospheric transport models.

  11. Contribution of airborne microbes to bacterial production and N2 fixation in seawater upon aerosol deposition

    NASA Astrophysics Data System (ADS)

    Rahav, Eyal; Ovadia, Galit; Paytan, Adina; Herut, Barak

    2016-01-01

    Aerosol deposition may supply a high diversity of airborne microbes, which can affect surface microbial composition and biological production. This study reports a diverse microbial community associated with dust and other aerosol particles, which differed significantly according to their geographical air mass origin. Microcosm bioassay experiments, in which aerosols were added to sterile (0.2 µm filtered and autoclaved) SE Mediterranean Sea (SEMS) water, were performed to assess the potential impact of airborne bacteria on bacterial abundance, production, and N2 fixation. Significant increase was observed in all parameters within a few hours, and calculations suggest that airborne microbes can account for one third in bacterial abundance and 50-100% in bacterial production and N2-fixation rates following dust/aerosol amendments in the surface SEMS. We show that dust/aerosol deposition can be a potential source of a wide array of microorganisms, which may impact microbial composition and food web dynamics in oligotrophic marine systems such as the SEMS.

  12. Renal uptake of bismuth-213 and its contribution to kidney radiation dose following administration of actinium-225-labeled antibody

    PubMed Central

    Schwartz, J; Jaggi, J S; O’Donoghue, J A; Ruan, S; McDevitt, M; Larson, S M; Scheinberg, D A; Humm, J L

    2011-01-01

    Clinical therapeutic studies using 225Ac-labeled antibodies have begun. Of major concern is renal toxicity that may result from the three alpha-emitting progeny generated following the decay of 225Ac. The purpose of this study was to determine the amount of 225Ac and non-equilibrium progeny in the mouse kidney after the injection of 225Ac-huM195 antibody and examine the dosimetric consequences. Groups of mice were sacrificed at 24, 96 and 144 h after injection with 225Ac-huM195 antibody and kidneys excised. One kidney was used for gamma ray spectroscopic measurements by a high-purity germanium (HPGe) detector. The second kidney was used to generate frozen tissue sections which were examined by digital autoradiography (DAR). Two measurements were performed on each kidney specimen: (1) immediately post-resection and (2) after sufficient time for any non-equilibrium excess 213Bi to decay completely. Comparison of these measurements enabled estimation of the amount of excess 213Bi reaching the kidney (γ-ray spectroscopy) and its sub-regional distribution (DAR). The average absorbed dose to whole kidney, determined by spectroscopy, was 0.77 (SD 0.21) Gy kBq−1, of which 0.46 (SD 0.16) Gy kBq−1 (i.e. 60%) was due to non-equilibrium excess 213Bi. The relative contributions to renal cortex and medulla were determined by DAR. The estimated dose to the cortex from non-equilibrium excess 213Bi (0.31 (SD 0.11) Gy kBq−1) represented ~46% of the total. For the medulla the dose contribution from excess 213Bi (0.81 (SD 0.28) Gy kBq−1) was ~80% of the total. Based on these estimates, for human patients we project a kidney-absorbed dose of 0.28 Gy MBq−1 following administration of 225Ac-huM195 with non-equilibrium excess 213Bi responsible for approximately 60% of the total. Methods to reduce renal accumulation of radioactive progeny appear to be necessary for the success of 225Ac radioimmunotherapy. PMID:21220845

  13. Renal uptake of bismuth-213 and its contribution to kidney radiation dose following administration of actinium-225-labeled antibody

    NASA Astrophysics Data System (ADS)

    Schwartz, J.; Jaggi, J. S.; O'Donoghue, J. A.; Ruan, S.; McDevitt, M.; Larson, S. M.; Scheinberg, D. A.; Humm, J. L.

    2011-02-01

    Clinical therapeutic studies using 225Ac-labeled antibodies have begun. Of major concern is renal toxicity that may result from the three alpha-emitting progeny generated following the decay of 225Ac. The purpose of this study was to determine the amount of 225Ac and non-equilibrium progeny in the mouse kidney after the injection of 225Ac-huM195 antibody and examine the dosimetric consequences. Groups of mice were sacrificed at 24, 96 and 144 h after injection with 225Ac-huM195 antibody and kidneys excised. One kidney was used for gamma ray spectroscopic measurements by a high-purity germanium (HPGe) detector. The second kidney was used to generate frozen tissue sections which were examined by digital autoradiography (DAR). Two measurements were performed on each kidney specimen: (1) immediately post-resection and (2) after sufficient time for any non-equilibrium excess 213Bi to decay completely. Comparison of these measurements enabled estimation of the amount of excess 213Bi reaching the kidney (γ-ray spectroscopy) and its sub-regional distribution (DAR). The average absorbed dose to whole kidney, determined by spectroscopy, was 0.77 (SD 0.21) Gy kBq-1, of which 0.46 (SD 0.16) Gy kBq-1 (i.e. 60%) was due to non-equilibrium excess 213Bi. The relative contributions to renal cortex and medulla were determined by DAR. The estimated dose to the cortex from non-equilibrium excess 213Bi (0.31 (SD 0.11) Gy kBq-1) represented ~46% of the total. For the medulla the dose contribution from excess 213Bi (0.81 (SD 0.28) Gy kBq-1) was ~80% of the total. Based on these estimates, for human patients we project a kidney-absorbed dose of 0.28 Gy MBq-1 following administration of 225Ac-huM195 with non-equilibrium excess 213Bi responsible for approximately 60% of the total. Methods to reduce renal accumulation of radioactive progeny appear to be necessary for the success of 225Ac radioimmunotherapy.

  14. Renal uptake of bismuth-213 and its contribution to kidney radiation dose following administration of actinium-225-labeled antibody.

    PubMed

    Schwartz, J; Jaggi, J S; O'Donoghue, J A; Ruan, S; McDevitt, M; Larson, S M; Scheinberg, D A; Humm, J L

    2011-02-01

    Clinical therapeutic studies using (225)Ac-labeled antibodies have begun. Of major concern is renal toxicity that may result from the three alpha-emitting progeny generated following the decay of (225)Ac. The purpose of this study was to determine the amount of (225)Ac and non-equilibrium progeny in the mouse kidney after the injection of (225)Ac-huM195 antibody and examine the dosimetric consequences. Groups of mice were sacrificed at 24, 96 and 144 h after injection with (225)Ac-huM195 antibody and kidneys excised. One kidney was used for gamma ray spectroscopic measurements by a high-purity germanium (HPGe) detector. The second kidney was used to generate frozen tissue sections which were examined by digital autoradiography (DAR). Two measurements were performed on each kidney specimen: (1) immediately post-resection and (2) after sufficient time for any non-equilibrium excess (213)Bi to decay completely. Comparison of these measurements enabled estimation of the amount of excess (213)Bi reaching the kidney (γ-ray spectroscopy) and its sub-regional distribution (DAR). The average absorbed dose to whole kidney, determined by spectroscopy, was 0.77 (SD 0.21) Gy kBq(-1), of which 0.46 (SD 0.16) Gy kBq(-1) (i.e. 60%) was due to non-equilibrium excess (213)Bi. The relative contributions to renal cortex and medulla were determined by DAR. The estimated dose to the cortex from non-equilibrium excess (213)Bi (0.31 (SD 0.11) Gy kBq(-1)) represented ∼46% of the total. For the medulla the dose contribution from excess (213)Bi (0.81 (SD 0.28) Gy kBq(-1)) was ∼80% of the total. Based on these estimates, for human patients we project a kidney-absorbed dose of 0.28 Gy MBq(-1) following administration of (225)Ac-huM195 with non-equilibrium excess (213)Bi responsible for approximately 60% of the total. Methods to reduce renal accumulation of radioactive progeny appear to be necessary for the success of (225)Ac radioimmunotherapy. PMID:21220845

  15. Contribution of particle counting in assessment of exposure to airborne microorganisms

    NASA Astrophysics Data System (ADS)

    Parat, Sylvie; Perdrix, Alain; Mann, Sylvie; Baconnier, Pierre

    The aim of the study was to determine the relationship between airborne bacterial concentrations and particle counts measured simultaneously at different sites. Andersen single stage viable particle samplers were used for microbial measurements while a Laser particle counter gave the cumulated counts of particles larger than 0.5 μm diameter. The first phase of the study was performed in two experimental rooms where the basic level of microbial contamination was low. Peaks of concentrations were generated by human activity and both bacterial and particle counts were monitored over 1 h. In the second phase, measurements were run for several days in three different buildings normally occupied. Natural variations of bacterial and particle counts were monitored: microbial measurements were performed each hour while particle counts were started with a 10 min frequency. Statistics revealed strong positive correlations between bacterial and particle counts in four sites out of five. Analyses of covariance used to compare the regression lines obtained in each area showed that except for two natural sites, the regression lines were significantly different, indicating that no absolute relationship can be established between the two parameters. Therefore, particle counting should, of course, not take the place of microorganism measurements, but combining particle counting with bioaerosols measurements may allow detection of rapid variations instantaneously and indicate further microbial measurements. This strategy should improve the assessment of people"s real exposure to airborne microorganisms.

  16. The contribution of the GRAV-D airborne gravity to geoid determination in the Great Lakes region

    NASA Astrophysics Data System (ADS)

    Li, Xiaopeng; Crowley, John W.; Holmes, Simon A.; Wang, Yan-Ming

    2016-05-01

    The current official North American Vertical Datum of 1988 (NAVD 88) and the International Great Lakes Datum of 1985 (IGLD 85) will be replaced by a new geoid-based vertical datum in 2022. The Gravity for the Redefinition of the American Vertical Datum (GRAV-D) project collects high-quality airborne gravity data to improve the quality of the gravitational model that underpins the geoid model. This paper validates the contribution of GRAV-D data in the Great Lakes region. Using the lake surface height measured by satellite altimetry as an independent data set, Global Gravity Models (GGMs) with/without the GRAV-D data are compared. The comparisons show that the improvement reaches decimeters over Lake Michigan where the historic gravity data have significant errors. Over all lakes, except Lake Erie, the GRAV-D data improve the accuracy of the gravitational model to 1-3 cm.

  17. Source apportionment of airborne particles in commercial aircraft cabin environment: Contributions from outside and inside of cabin

    NASA Astrophysics Data System (ADS)

    Li, Zheng; Guan, Jun; Yang, Xudong; Lin, Chao-Hsin

    2014-06-01

    Airborne particles are an important type of air pollutants in aircraft cabin. Finding sources of particles is conducive to taking appropriate measures to remove them. In this study, measurements of concentration and size distribution of particles larger than 0.3 μm (PM>0.3) were made on nine short haul flights from September 2012 to March 2013. Particle counts in supply air and breathing zone air were both obtained. Results indicate that the number concentrations of particles ranged from 3.6 × 102 counts L-1 to 1.2 × 105 counts L-1 in supply air and breathing zone air, and they first decreased and then increased in general during the flight duration. Peaks of particle concentration were found at climbing, descending, and cruising phases in several flights. Percentages of particle concentration in breathing zone contributed by the bleed air (originated from outside) and cabin interior sources were calculated. The bleed air ratios, outside airflow rates and total airflow rates were calculated by using carbon dioxide as a ventilation tracer in five of the nine flights. The calculated results indicate that PM>0.3 in breathing zone mainly came from unfiltered bleed air, especially for particle sizes from 0.3 to 2.0 μm. And for particles larger than 2.0 μm, contributions from the bleed air and cabin interior were both important. The results would be useful for developing better cabin air quality control strategies.

  18. Manufactured and Airborne Nanoparticle Cardiopulmonary Interactions: A Review of Mechanisms and the Possible Contribution of Mast Cells

    PubMed Central

    Shannahan, Jonathan H.; Kodavanti, Urmila P.; Brown, Jared M.

    2013-01-01

    Human inhalation exposures to manufactured nanoparticles (NP) and airborne ultrafine particles (UFP) continues to increase in both occupational and environmental settings. UFP exposures have been associated with increased cardiovascular mortality and morbidity, while ongoing research supports adverse systemic and cardiovascular health effects after NP exposures. Adverse cardiovascular health effects include alterations in heart rate variability, hypertension, thrombosis, arrhythmias, increased myocardial infarction, and atherosclerosis. Exactly how UFP and NP cause these negative cardiovascular effects is poorly understood, however a variety of mediators and mechanisms have been proposed. UFP and NP, as well as their soluble components, are known to systemically translocate from the lung. Translocated particles could mediate cardiovascular toxicity through direct interactions with the vasculature, blood, and heart. Recent study suggests that sensory nerve stimulation within the lung may also contribute to UFP- and NP-induced acute cardiovascular alterations. Activation of sensory nerves, such as C-fibers, within the lung may result in altered cardiac rhythm and function. Lastly, release of pulmonary-derived mediators into systemic circulation has been proposed to facilitate cardiovascular effects. In general, these proposed pulmonary-derived mediators include pro-inflammatory cytokines, oxidatively-modified macromolecules, vasoactive proteins, and prothrombotic factors. These pulmonary-derived mediators have been postulated to contribute to the subsequent prothrombotic, atherogenic, and inflammatory effects after exposure. This review will evaluate the potential contribution of individual mediators and mechanisms in facilitating cardiopulmonary toxicity following inhalation of UFP and NP. Lastly we will appraise the literature and propose a hypothesis regarding the possible role of mast cells in contributing to these systemic effects. PMID:22486349

  19. Carbon content of common airborne fungal species and fungal contribution to aerosol organic carbon in a subtropical city

    NASA Astrophysics Data System (ADS)

    Cheng, Jessica Y. W.; Chan, Chak K.; Lee, C.-T.; Lau, Arthur P. S.

    Interest in the role and contribution of fungi to atmospheric aerosols and processes grows in the past decade. Substantial data or information such as fungal mass or carbon loading to ambient aerosols is however still lacking. This study aimed to quantify the specific organic carbon content (OC per spore) of eleven fungal species commonly found airborne in the subtropics, and estimated their contribution to organic carbon in aerosols. The specific OC contents showed a size-dependent relationship ( r = 0.64, p < 0.05) and ranged from 3.6 to 201.0 pg carbon per spore or yeast cell, giving an average of 6.0 pg carbon per spore (RSD 51%) for spore or cell size less than 10 μm. In accounting for natural variations in the composition and abundance of fungal population, weighted-average carbon content for field samples was adopted using the laboratory determined specific OC values. An average of 5.97 pg carbon per spore (RSD 3.8%) was enumerated from 28 field samples collected at the university campus. The mean fungal OC concentration was 3.7, 6.0 and 9.7 ng m -3 in PM 2.5, PM 2.5-10 and PM 10, respectively. These corresponded to 0.1%, 1.2% and 0.2% of the total OC in PM 2.5, PM 2.5-10 and PM 10, respectively. In the study period, rain provided periods with low total OC but high fungal prevalence and fungi contributed 7-32% OC in PM 2.5-10 or 2.4-7.1% OC in PM 10. More extensive studies are deserved to better understand the spatial-, temporal- and episodic dependency on the fungal OC contribution to the atmospheric aerosols.

  20. Manufactured and Airborne Nanoparticle Cardiopulmonary Interactions: A Review of Mechanisms and the Possible Contribution of Mast Cells

    EPA Science Inventory

    Human inhalation exposures to manufactured nanoparticles (NP) and airborne ultrafine particles (UFP) continues to increase in both occupational and environmental settings. UFP exposures have been associated with increased cardiovascular mortality and morbidity, while ongoing res...

  1. Tribochemistry of Bismuth and Bismuth Salts for Solid Lubrication.

    PubMed

    Gonzalez-Rodriguez, Pablo; van den Nieuwenhuijzen, Karin J H; Lette, Walter; Schipper, Dik J; Ten Elshof, Johan E

    2016-03-23

    One of the main trends in the past decades is the reduction of wastage and the replacement of toxic compounds in industrial processes. Some soft metallic particles can be used as nontoxic solid lubricants in high-temperature processes. The behavior of bismuth metal particles, bismuth sulfide (Bi2S3), bismuth sulfate (Bi2(SO4)3), and bismuth oxide (Bi2O3) as powder lubricants was studied in a range of temperatures up to 580 °C. The mechanical behavior was examined using a high-temperature pin-on-disc setup, with which the friction force between two flat-contact surfaces was recorded. The bismuth-lubricated surfaces showed low coefficients of friction (μ ≈ 0.08) below 200 °C. Above the melting temperature of the metal powder at 271 °C, a layer of bismuth oxide developed and the friction coefficient increased. Bismuth oxide showed higher friction coefficients at all temperatures. Bismuth sulfide exhibited partial oxidation upon heating but the friction coefficient decreased to μ ≈ 0.15 above 500 °C, with the formation of bismuth oxide-sulfate, while some bismuth sulfate remained. All surfaces were studied by X-ray diffraction (XRD), confocal microscopy, high-resolution scanning electron microscopy (HR-SEM), and energy-dispersive X-ray spectroscopy (EDS). This study reveals how the partial oxidation of bismuth compounds at high temperatures affects their lubrication properties, depending on the nature of the bismuth compound. PMID:26936490

  2. Magnetometer uses bismuth-selenide

    NASA Technical Reports Server (NTRS)

    Woollman, J. A.; Spain, I. L.; Beale, H.

    1972-01-01

    Characteristics of bismuth-selenide magnetometer are described. Advantages of bismuth-selenide magnetometer over standard magnetometers are stressed. Thermal stability of bismuth-selenide magnetometer is analyzed. Linearity of output versus magnetic field over wide range of temperatures is reported.

  3. Spread of Coxiella burnetii between dairy cattle herds in an enzootic region: modelling contributions of airborne transmission and trade.

    PubMed

    Pandit, Pranav; Hoch, Thierry; Ezanno, Pauline; Beaudeau, François; Vergu, Elisabeta

    2016-01-01

    Q fever, a worldwide zoonotic disease caused by Coxiella burnetii, is a looming concern for livestock and public health. Epidemiological features of inter-herd transmission of C. burnetii in cattle herds by wind and trade of cows are poorly understood. We present a novel dynamic spatial model describing the inter-herd regional spread of C. burnetii in dairy cattle herds, quantifying the ability of airborne transmission and animal trade in C. burnetii propagation in an enzootic region. Among all the new herd infections, 92% were attributed to airborne transmission and the rest to cattle trade. Infections acquired following airborne transmission were shown to cause relatively small and ephemeral intra-herd outbreaks. On the contrary, disease-free herds purchasing an infectious cow experienced significantly higher intra-herd prevalence. The results also indicated that, for short duration, both transmission routes were independent from each other without any synergistic effect. The model outputs applied to the Finistère department in western France showed satisfactory sensitivity (0.71) and specificity (0.80) in predicting herd infection statuses at the end of one year in a neighbourhood of 3 km around expected incident herds, when compared with data. The model developed here thus provides important insights into the spread of C. burnetii between dairy cattle herds and paves the way for implementation and assessment of control strategies. PMID:27048416

  4. THORIUM DISPERSION IN BISMUTH

    DOEpatents

    Bryner, J.S.

    1961-07-01

    The growth of thorium bismutaide particles, which are formed when thorium is suspended in liquid bismuth, is inhibited when the liquid metal suspension is being flowed through a reactor and through a heat exchanger in sequence. It involves the addition of as little as 1 part by weight of tellurium to 100 parts of thorium. This addition is sufficient to inhibit particle growth and agglomeration.

  5. Contribution of the airborne geophysical survey to the study of the regolith : A case study in southern Paris Basin.

    NASA Astrophysics Data System (ADS)

    Prognon, Francois; Lacquement, Fréderic; Deparis, Jacques; Martelet, Guillaume; Perrin, José

    2010-05-01

    Studies of soil and subsoil, also called regolith, are at the crossroads of scientific new challenging questions as well as new environmental needs. Historically, geological maps were focussed on solid geology. Present societal needs increasingly require knowledge of regolith properties: superficial studies combining geology, geochemistry and geophysics become essential to better understand the natural processes which govern the repartition and evolution of subsoil formations. Such progress is critical to better orient the use and management of natural and groundwater resources. Among other techniques, airborne geophysics is appropriate to provide information on near surface, because of i) its high spatial coverage ii) the rapidity of acquisition and iii) the variety of available sensors (magnetic, spectral radiometry, electromagnetic …). We illustrate the results of an airborne geophysical survey carried out in France, in "Région Centre" administrative region in the southern part of the Paris Basin. Spectral radiometry data were collected throughout "Région Centre" with a line spacing of 1 km. This method provides maps of potassium (K), uranium (U) and thorium (Th) which are the only naturally occurring elements with direct or indirect radioisotopes that produce gamma rays of sufficient intensity to be measured at airborne survey heights. Gamma-rays emitted from the Earth surface are related to the primary mineralogy and geochemistry of the bedrock and/or the nature of secondary weathering including regolith materials. Obtained images are confronted with former geological investigations (1:50 000e geological maps). Geophysical data and geological maps are generally consistent on most of the covered area since the first-rate information delivered by the spectrometry derives from the geochemistry of the solid geology. Second-rate gamma-ray responses come from superimposed allochtonous deposits as well as in situ geochemical modifications. For instance

  6. A multivariate receptor modeling study of air-borne particulate PAHs: Regional contributions in a roadside environment.

    PubMed

    Kim, Bong Mann; Lee, Seung-Bok; Kim, Jin Young; Kim, Sunwha; Seo, Jihoon; Bae, Gwi-Nam; Lee, Ji Yi

    2016-02-01

    Understanding the geographic source contributions by particulate polycyclic aromatic hydrocarbons (PAHs) is important for the Korean peninsula due to its downwind location from source areas. Regional influence of particulate PAHs was previously identified using diagnostic ratios applied to mobile source dominated roadside sampling data (Kim et al., 2012b). However, no study has yet been conducted to quantify the regional source contributions. We applied a multivariate receptor modeling tool to identify and quantify the regional source contributions to particulate PAHs in Seoul. Sampling of roadside particulate PAHs was conducted in Seoul, Korea for four years between May 2005 and April 2009, and data analysis was performed with a new multivariate receptor model, Solver for Mixture Problem (SMP). The SMP model identified two sources, local mobile source and transported regional source, and quantified their source contributions. Analysis of the particulate PAHs data reveals three types of episodic periods: a high regional source contribution period with one case, a high mobile source contribution period with three cases, and a normal contribution period with eight cases. Four-year average particulate PAHs source contributions from the two sources are 4.6 ng m(-3) and 10.7 ng m(-3) for regional and mobile sources, respectively and equivalent to 30% and 70% of the total estimated contribution from each of these sources. PMID:26473551

  7. 21 CFR 73.2110 - Bismuth citrate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 1 2013-04-01 2013-04-01 false Bismuth citrate. 73.2110 Section 73.2110 Food and... ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2110 Bismuth citrate. (a) Identity. The color additive bismuth citrate is the synthetically prepared crystalline salt of bismuth and citric acid,...

  8. 21 CFR 73.2110 - Bismuth citrate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 1 2014-04-01 2014-04-01 false Bismuth citrate. 73.2110 Section 73.2110 Food and... ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2110 Bismuth citrate. (a) Identity. The color additive bismuth citrate is the synthetically prepared crystalline salt of bismuth and citric acid,...

  9. 21 CFR 73.2110 - Bismuth citrate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 1 2012-04-01 2012-04-01 false Bismuth citrate. 73.2110 Section 73.2110 Food and... ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2110 Bismuth citrate. (a) Identity. The color additive bismuth citrate is the synthetically prepared crystalline salt of bismuth and citric acid,...

  10. 21 CFR 73.2110 - Bismuth citrate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 1 2011-04-01 2011-04-01 false Bismuth citrate. 73.2110 Section 73.2110 Food and... ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2110 Bismuth citrate. (a) Identity. The color additive bismuth citrate is the synthetically prepared crystalline salt of bismuth and citric acid,...

  11. 21 CFR 73.2110 - Bismuth citrate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Bismuth citrate. 73.2110 Section 73.2110 Food and... ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2110 Bismuth citrate. (a) Identity. The color additive bismuth citrate is the synthetically prepared crystalline salt of bismuth and citric acid,...

  12. Bismuth ochers from San Diego Co., California

    USGS Publications Warehouse

    Schaller, W.T.

    1911-01-01

    The chief points brought out in this paper may be briefly summarized as follows: (1) The existence of natural Bi2O3 has not been established. (2) Natural bismite or bismuth ocher, when pure, is more probably a bismuth hydroxide. (3) The bismuth ochers from San Diego County, California, are either a bismuth hydroxide or bismuth vanadate, pucherite, or mixtures of these two. (4) Pucherite has been found noncrystallin and determined for the first time in the United States.

  13. Energetics of bismuth vanadate

    SciTech Connect

    Nagabhushana, G.P.; Tavakoli, A.H.; Navrotsky, A.

    2015-05-15

    Bismuth vanadate has gained considerable interest as a photoanode for water splitting reactions under visible light. It exists in four different polymorphs, out of which three of them have been synthesized. Thermodynamic properties of these three polymorphs are investigated using high temperature oxide melt solution calorimetry. The monoclinic scheelite phase which exhibits photocatalytic activity under visible light is found to be the most stable polymorph, followed by tetragonal scheelite which exhibits activity under UV light. The photocatalytically inactive tetragonal zircon form is found to be the least stable polymorph. The small difference in enthalpy of formation between the two scheelite structures (−8 kJ/mol) is in accord with the reversibility of the transformation between them and the larger difference between the most stable monoclinic phase and the least stable tetragonal zircon phase (−23 kJ/mol) is in accord with the irreversible (monoclinic→tetragonal zircon) phase transformation. - Graphical abstract: Schematic representation of polymorphic transitions in BiVO{sub 4} along with their formation enthalpies. - Highlights: • Bismuth vanadate crystallizes in three different polymorphs. • High temperature calorimetric measurements were made to determine their formation enthalpies. • Enthalpy of formation decreases in the order BV-ms→BV-ts→BV-tz. • Photocatalytically active monoclinic-BiVO{sub 4} was found to be the most stable polymorph.

  14. Energetics of bismuth vanadate

    NASA Astrophysics Data System (ADS)

    Nagabhushana, G. P.; Tavakoli, A. H.; Navrotsky, A.

    2015-05-01

    Bismuth vanadate has gained considerable interest as a photoanode for water splitting reactions under visible light. It exists in four different polymorphs, out of which three of them have been synthesized. Thermodynamic properties of these three polymorphs are investigated using high temperature oxide melt solution calorimetry. The monoclinic scheelite phase which exhibits photocatalytic activity under visible light is found to be the most stable polymorph, followed by tetragonal scheelite which exhibits activity under UV light. The photocatalytically inactive tetragonal zircon form is found to be the least stable polymorph. The small difference in enthalpy of formation between the two scheelite structures (-8 kJ/mol) is in accord with the reversibility of the transformation between them and the larger difference between the most stable monoclinic phase and the least stable tetragonal zircon phase (-23 kJ/mol) is in accord with the irreversible (monoclinic→tetragonal zircon) phase transformation.

  15. Mineral resource of the month: bismuth

    USGS Publications Warehouse

    Carlin, James F.

    2006-01-01

    Bismuth compounds are most known for their soothing effects on the stomach, wounds and sores. These properties make the compounds an essential part of many medicinal and cosmetic preparations, which until 1930 accounted for about 90 percent of the bismuth used. The subsequent development of low-melting alloys and chemical catalysts containing bismuth, as well as its use as an additive to casting alloys, has resulted in a wider variety of industrial applications for bismuth.

  16. 21 CFR 73.1162 - Bismuth oxychloride.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 1 2014-04-01 2014-04-01 false Bismuth oxychloride. 73.1162 Section 73.1162 Food... COLOR ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1162 Bismuth oxychloride. (a) Identity. (1) The color additive bismuth oxychloride is a synthetically prepared white or nearly white amorphous or...

  17. 21 CFR 73.1162 - Bismuth oxychloride.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 1 2012-04-01 2012-04-01 false Bismuth oxychloride. 73.1162 Section 73.1162 Food... COLOR ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1162 Bismuth oxychloride. (a) Identity. (1) The color additive bismuth oxychloride is a synthetically prepared white or nearly white amorphous or...

  18. 21 CFR 73.1162 - Bismuth oxychloride.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Bismuth oxychloride. 73.1162 Section 73.1162 Food... COLOR ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1162 Bismuth oxychloride. (a) Identity. (1) The color additive bismuth oxychloride is a synthetically prepared white or nearly white amorphous or...

  19. 21 CFR 73.2162 - Bismuth oxychloride.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Bismuth oxychloride. 73.2162 Section 73.2162 Food... COLOR ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2162 Bismuth oxychloride. (a) Identity and specifications. (1) The color additive bismuth oxychloride shall conform in identity and specifications to...

  20. 21 CFR 73.2162 - Bismuth oxychloride.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 1 2014-04-01 2014-04-01 false Bismuth oxychloride. 73.2162 Section 73.2162 Food... COLOR ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2162 Bismuth oxychloride. (a) Identity and specifications. (1) The color additive bismuth oxychloride shall conform in identity and specifications to...

  1. 21 CFR 73.2162 - Bismuth oxychloride.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 1 2013-04-01 2013-04-01 false Bismuth oxychloride. 73.2162 Section 73.2162 Food... COLOR ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2162 Bismuth oxychloride. (a) Identity and specifications. (1) The color additive bismuth oxychloride shall conform in identity and specifications to...

  2. 21 CFR 73.2162 - Bismuth oxychloride.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 1 2011-04-01 2011-04-01 false Bismuth oxychloride. 73.2162 Section 73.2162 Food... COLOR ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2162 Bismuth oxychloride. (a) Identity and specifications. (1) The color additive bismuth oxychloride shall conform in identity and specifications to...

  3. 21 CFR 73.2162 - Bismuth oxychloride.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 1 2012-04-01 2012-04-01 false Bismuth oxychloride. 73.2162 Section 73.2162 Food... COLOR ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2162 Bismuth oxychloride. (a) Identity and specifications. (1) The color additive bismuth oxychloride shall conform in identity and specifications to...

  4. 21 CFR 73.1162 - Bismuth oxychloride.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 1 2013-04-01 2013-04-01 false Bismuth oxychloride. 73.1162 Section 73.1162 Food... COLOR ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1162 Bismuth oxychloride. (a) Identity. (1) The color additive bismuth oxychloride is a synthetically prepared white or nearly white amorphous or...

  5. 21 CFR 73.1162 - Bismuth oxychloride.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 1 2011-04-01 2011-04-01 false Bismuth oxychloride. 73.1162 Section 73.1162 Food... COLOR ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1162 Bismuth oxychloride. (a) Identity. (1) The color additive bismuth oxychloride is a synthetically prepared white or nearly white amorphous or...

  6. Bismuth-ring-doped fibres

    SciTech Connect

    Zlenko, Aleksandr S; Dvoirin, Vladislav V; Bogatyrev, Vladimir A; Firstov, Sergei V; Akhmetshin, Ural G

    2009-11-30

    A new process for bismuth doping of optical fibres is proposed in which the dopant is introduced into a thin layer surrounding the fibre core. This enables bismuth stabilisation in the silica glass, with no limitations on the core composition. In particular, the GeO{sub 2} content of the fibre core in this study is 16 mol %. Spectroscopic characterisation of such fibres and optical gain measurements suggest that the proposed approach has considerable potential for laser applications. (optical fibres and fibreoptic sensors)

  7. Third order nonlinear optical properties of bismuth zinc borate glasses

    SciTech Connect

    Shanmugavelu, B.; Ravi Kanth Kumar, V. V.; Kuladeep, R.; Narayana Rao, D.

    2013-12-28

    Third order nonlinear optical characterization of bismuth zinc borate glasses are reported here using different laser pulse durations. Bismuth zinc borate glasses with compositions xBi{sub 2}O{sub 3}-30ZnO-(70-x) B{sub 2}O{sub 3} (where x = 30, 35, 40, and 45 mol. %) have been prepared by melt quenching method. These glasses were characterized by Raman, UV-Vis absorption, and Z scan measurements. Raman and UV-Vis spectroscopic results indicate that non-bridging oxygens increase with increase of bismuth content in the glass. Nonlinear absorption and refraction behavior in the nanosecond (ns), picosecond (ps), and femtosecond (fs) time domains were studied in detail. Strong reverse saturable absorption due to dominant two-photon absorption (TPA) was observed with both ps and fs excitations. In the case of ns pulse excitations, TPA and free-carrier absorption processes contribute for the nonlinear absorption. Two-photon absorption coefficient (β) and the absorption cross section due to free carriers (σ{sub e}) are estimated by theoretical fit of the open aperture Z-scan measurements and found to be dependent on the amount of bismuth oxide in the glass composition. In both ns and fs regimes the sign and magnitude of the third order nonlinearity are evaluated, and the optical limiting characteristics are also reported.

  8. Ab initio energetics of lanthanum substitution in ferroelectric bismuth titanate

    NASA Astrophysics Data System (ADS)

    Shah, S. H.; Bristowe, P. D.

    2011-04-01

    Using first principles calculations and atomistic thermodynamics the bulk and defect properties of orthorhombic bismuth titanate (Bi4Ti3O12) and bismuth lanthanum titanate (Bi3.25La0.75Ti3O12) have been investigated. Heats of formation, valid chemical conditions for synthesis, lanthanum substitution energies and oxygen and bismuth vacancy formation energies have been computed. The study improves our understanding of how native point defects and substitutional impurities influence the ferroelectric properties of these layered perovskite materials. It is found that lanthanum incorporation could occur on either of the two distinct bismuth sites in the structure and that the effect of substitution is to increase the formation energy of nearby native oxygen vacancies. The results provide direct atomistic evidence over a range of chemical conditions supporting the suggestion that lanthanum incorporation reduces the oxygen vacancy concentration. Oxygen vacancies contribute to ferroelectric fatigue by interacting strongly with domain walls, and therefore a decrease in their concentration is beneficial. The conditions that favor the greatest reduction in oxygen vacancy concentration are described.

  9. Third order nonlinear optical properties of bismuth zinc borate glasses

    NASA Astrophysics Data System (ADS)

    Shanmugavelu, B.; Ravi Kanth Kumar, V. V.; Kuladeep, R.; Narayana Rao, D.

    2013-12-01

    Third order nonlinear optical characterization of bismuth zinc borate glasses are reported here using different laser pulse durations. Bismuth zinc borate glasses with compositions xBi2O3-30ZnO-(70-x) B2O3 (where x = 30, 35, 40, and 45 mol. %) have been prepared by melt quenching method. These glasses were characterized by Raman, UV-Vis absorption, and Z scan measurements. Raman and UV-Vis spectroscopic results indicate that non-bridging oxygens increase with increase of bismuth content in the glass. Nonlinear absorption and refraction behavior in the nanosecond (ns), picosecond (ps), and femtosecond (fs) time domains were studied in detail. Strong reverse saturable absorption due to dominant two-photon absorption (TPA) was observed with both ps and fs excitations. In the case of ns pulse excitations, TPA and free-carrier absorption processes contribute for the nonlinear absorption. Two-photon absorption coefficient (β) and the absorption cross section due to free carriers (σe) are estimated by theoretical fit of the open aperture Z-scan measurements and found to be dependent on the amount of bismuth oxide in the glass composition. In both ns and fs regimes the sign and magnitude of the third order nonlinearity are evaluated, and the optical limiting characteristics are also reported.

  10. Fourth Airborne Geoscience Workshop

    NASA Technical Reports Server (NTRS)

    1991-01-01

    The focus of the workshop was on how the airborne community can assist in achieving the goals of the Global Change Research Program. The many activities that employ airborne platforms and sensors were discussed: platforms and instrument development; airborne oceanography; lidar research; SAR measurements; Doppler radar; laser measurements; cloud physics; airborne experiments; airborne microwave measurements; and airborne data collection.

  11. Airborne laser

    NASA Astrophysics Data System (ADS)

    Lamberson, Steven E.

    2002-06-01

    The US Air Force Airborne Laser (ABL) is an airborne, megawatt-class laser system with a state-of-the-art atmospheric compensation system to destroy enemy ballistic missiles at long ranges. This system will provide both deterrence and defense against the use of such weapons during conflicts. This paper provides an overview of the ABL weapon system including: the notional operational concept, the development approach and schedule, the overall aircraft configuration, the technologies being incorporated in the ABL, and the risk reduction approach being utilized to ensure program success.

  12. Bismuth electrodes, an alternative in stripping voltammetry

    NASA Astrophysics Data System (ADS)

    Barón-Jaimez, J.; Joya, M. R.; Barba-Ortega, J.

    2013-11-01

    The heavy metals are known as highly toxic contaminants, the processes carried out in industry contribute that finally they remain dispersed in effluents and sewage, doing part of the food chain. The importance of controlling the levels of these heavy metals has become an international policy, so it has generated interest in developing new analytical methodologies for its determination [1, 2, 3, 4]. The stripping voltammetry has been considered as a family of electro-sensitive analytical techniques useful for the determination of trace levels of many metals in environmental, clinical and industrial samples [3, 4]. This work presents an overview of these bismuth-based electrodes which were introduced around 2000, which have interesting characteristics for detection of heavy metals and which represent an alternative to mercury electrodes.

  13. SEPARATION OF PLUTONIUM HYDROXIDE FROM BISMUTH HYDROXIDE

    DOEpatents

    Watt, G.W.

    1958-08-19

    An tmproved method is described for separating plutonium hydroxide from bismuth hydroxide. The end product of the bismuth phosphate processes for the separation amd concentration of plutonium is a inixture of bismuth hydroxide amd plutonium hydroxide. It has been found that these compounds can be advantageously separated by treatment with a reducing agent having a potential sufficient to reduce bismuth hydroxide to metalltc bisinuth but not sufficient to reduce the plutonium present. The resulting mixture of metallic bismuth and plutonium hydroxide can then be separated by treatment with a material which will dissolve plutonium hydroxide but not metallic bismuth. Sodiunn stannite is mentioned as a preferred reducing agent, and dilute nitric acid may be used as the separatory solvent.

  14. Aspects of the magmatic geochemistry of bismuth

    USGS Publications Warehouse

    Greenland, L.P.; Gottfried, D.; Campbell, E.Y.

    1973-01-01

    Bismuth has been determined in 74 rocks from a differentiated tholeiitic dolerite, two calc-alkaline batholith suites and in 66 mineral separates from one of the batholiths. Average bismuth contents, weighted for rock type, of the Great Lake (Tasmania) dolerite, the Southern California batholith and the Idaho batholith are, 32, 50 and 70 ppb respectively. All three bodies demonstrate an enrichment of bismuth in residual magmas with magmatic differentiation. Bismuth is greatly enriched (relative to the host rock) in the calcium-rich accessory minerals, apatite and sphene, but other mineral analyses show that a Bi-Ca association is of little significance to the magmatic geochemistry of bismuth. Most of the bismuth, in the Southern California batholith at least, occurs in a trace mineral phase (possibly sulfides) present as inclusions in the rock-forming minerals. ?? 1973.

  15. Atmospheric Transport Studies Using In-situ Airborne Gas Chromatograph Measurements: An Overview of the NOAA Climate Monitoring and Diagnostics Laboratory (CMDL) Contribution.

    NASA Astrophysics Data System (ADS)

    Moore, F.; Dutton, G.; Elkins, J.; Hall, B.; Hurst, D.; Nance, D.; Ray, E.; Romashkin, P.; Thompson, T.; Volk, C. M.

    2005-12-01

    Accurate models of atmospheric transport are crucial to our current understanding of ozone production/loss and its coupling with climate change. Over the last ``20 years'', improvements in the ability to predict ``The Antarctic Ozone Hole and Polar Ozone Loss'' have tracked improvements in transport models. Data taken from the NOAA/CMDL airborne in-situ GC's (ACATS, LACE, PANTHER, and UCATS) have and will continue to play key roles in quantifying many aspects of stratospheric transport. Our data have been used in many of the model assessments to date. We will display an overview of the transport issues studied over the years using our data. They include descent with mixing within and into the polar vortex, entrainment of mid-latitude air across the vortex edge, upwelling and entrainment in the tropical pipe, isentropic transport across the tropopause into the lowermost stratosphere, mean ages of air parcels in the stratosphere, and stratospheric path distributions. ACATS - Airborne Chromatograph for Atmospheric Trace Species LACE - Lightweight Airborne Chromatograph Experiment PANTHER - PAN and Other Trace Hydrohalocarbons ExpeRiment UCATS - Unmanned aerial systems Chromatograph for Atmospheric Trace Species

  16. Battery performance enhancement with additions of bismuth

    NASA Astrophysics Data System (ADS)

    Manders, J. E.; Lam, L. T.; de Marco, R.; Douglas, J. D.; Pillig, R.; Rand, D. A. J.

    1994-02-01

    Automotive and valve-regulated batteries (VRBs) of typical commercial design have been constructed using positive and negative plates produced from leady oxide that is doped with 0.06 wt.% bismuth. The doping is performed by adding bismuth (III) oxide powder during the paste-mixing stage. Both battery designs have been subjected to endurance tests (automotive batteries: JIS cycle-life test; VRBs: repetitive 3-h discharge) in parallel with batteries that are similar in all respects but do not contain bismuth. A strategy and necessary hardware have been developed to measure the gassing properties of the VRBs during both charge and discharge. The procedure involves monitoring the internal pressure with high-precision pressure transducers. For automotive batteries, doping with bismuth produces no significant differences in JIS cycle life. By contrast, both the endurance and the capacity of VRBs are found to be enhanced by the presence of bismuth. Furthermore, bismuth reduces the build-up in gas pressure (mainly oxygen) in VRBs during constant-current charging. These results suggest that future specifications for leady oxide should include a minimum - rather than a maximum - bismuth content. In this respect, although studies performed to date show that significant advantages can be achieved with 0.06 wt.% bismuth in the active material, the optimum bismuth level has yet to be established.

  17. BISMUTH PHOSPHATE CARRIER PROCESS FOR Pu RECOVERY

    DOEpatents

    Finzel, T.G.

    1959-02-01

    An improvement in the bismuth phosphate carrier precipitation process for recovering plutonium is described. It has been found that a more granular and more easily filterable carrier precipitiite is formed if the addition of the bismuth and phosphate ions is effected by first adding 9/10 of the bismuth ions necessary, then slowly adding all of the source of the phosphate ions to be incorporated in the precipitate, while digesting at 75 C and afterwards incorporating the remainder of the total bismuth ions necessary

  18. Multiferroic bismuth ferrite material core based inductive displacement sensor

    NASA Astrophysics Data System (ADS)

    Rajeswari, R.; Biswal, M. R.; Nanda, J.; Mishra, N. C.

    2012-07-01

    In this research, an inductive displacement sensor with multiferroic bismuth ferrite core has been realized. The bismuth ferrite sample is synthesized and its structural and dielectric properties are studied. A rod-shaped bismuth ferrite core is prepared and displaced through the inductor of a RLC circuit. The performance of the prepared bismuth ferrite core has been compared with a commercially available ferrite core.

  19. IR luminescence in bismuth-doped germanate glasses and fibres

    SciTech Connect

    Pynenkov, A A; Firstov, Sergei V; Panov, A A; Firstova, E G; Nishchev, K N; Bufetov, Igor' A; Dianov, Evgenii M

    2013-02-28

    We have studied the optical properties of lightly bismuth doped ({<=}0.002 mol %) germanate glasses prepared in an alumina crucible. The glasses are shown to contain bismuth-related active centres that have been identified previously only in bismuth-doped fibres produced by MCVD. With increasing bismuth concentration in the glasses, their luminescence spectra change markedly, which is attributable to interaction between individual bismuth centres. (optical fibres)

  20. D-penicillamine does not increase urinary bismuth excretion in patients treated with tripotassium dicitrato bismuthate.

    PubMed Central

    Nwokolo, C U; Pounder, R E

    1990-01-01

    Twenty-four urinary bismuth excretion was measured in five patients who had been treated with tripotassium dicitrato bismuthate, before and after single 1 g oral dose of D-penicillamine. Before dosing with D-penicillamine, the median 24 h urinary bismuth output was 55 micrograms 24 h-1 (range 17-156 micrograms 24 h-1) and following dosing with D-penicillamine the median 24 h urinary bismuth output was 53 micrograms 24 h-1 (range 12-156 micrograms 24 h-1). D-penicillamine does not facilitate the urinary excretion of bismuth, hence it is unsuitable for use as an oral chelator in patients with bismuth intoxication. PMID:2291879

  1. PROCESS OF COATING METALS WITH BISMUTH OR BISMUTH-BASE ALLOYS

    DOEpatents

    Beach, J.G.

    1958-01-28

    A method is described for producing coatings of bismuth or bismuth alloys on a metal base. This is accomplished by electrodepositing the bismuth from an aqueous solution of BiCl/sub 3/, and by making the metal base alternately the cathode and the anode, the cathode periods being twice as long as the anode periods. In one embodiment a nickel coating is first electrodeposited in a known way, and this nickel plated piece is tae base upon which tae bismuth is deposited by the process of this patent. The coated piece is then heat treated to produce a homogeneous Ni--Bi alloy by diffusion.

  2. Induced electronic anisotropy in bismuth thin films

    SciTech Connect

    Liao, Albert D.; Yao, Mengliang; Opeil, Cyril; Katmis, Ferhat; Moodera, Jagadeesh S.; Li, Mingda; Tang, Shuang; Dresselhaus, Mildred S.

    2014-08-11

    We use magneto-resistance measurements to investigate the effect of texturing in polycrystalline bismuth thin films. Electrical current in bismuth films with texturing such that all grains are oriented with the trigonal axis normal to the film plane is found to flow in an isotropic manner. By contrast, bismuth films with no texture such that not all grains have the same crystallographic orientation exhibit anisotropic current flow, giving rise to preferential current flow pathways in each grain depending on its orientation. Extraction of the mobility and the phase coherence length in both types of films indicates that carrier scattering is not responsible for the observed anisotropic conduction. Evidence from control experiments on antimony thin films suggests that the anisotropy is a result of bismuth's large electron effective mass anisotropy.

  3. Bismuth-based electrochemical stripping analysis

    DOEpatents

    Wang, Joseph

    2004-01-27

    Method and apparatus for trace metal detection and analysis using bismuth-coated electrodes and electrochemical stripping analysis. Both anodic stripping voltammetry and adsorptive stripping analysis may be employed.

  4. Infrared surface polaritons on bismuth

    NASA Astrophysics Data System (ADS)

    Khalilzadeh-Rezaie, Farnood; Smith, Christian W.; Nath, Janardan; Nader, Nima; Shahzad, Monas; Cleary, Justin W.; Avrutsky, Ivan; Peale, Robert E.

    2015-01-01

    Optical constants for evaporated bismuth (Bi) films were measured by ellipsometry and compared with those published for single crystal and melt-cast polycrystalline Bi in the wavelength range of 1 to 40 μm. The bulk plasma frequency ωp and high-frequency limit to the permittivity ε∞ were determined from the long-wave portion of the permittivity spectrum, taking previously published values for the relaxation time τ and effective mass m*. This part of the complex permittivity spectrum was confirmed by comparing calculated and measured reflectivity spectra in the far-infrared. Properties of surface polaritons (SPs) in the long-wave infrared were calculated to evaluate the potential of Bi for applications in infrared plasmonics. Measured excitation resonances for SPs on Bi lamellar gratings agree well with calculated resonance spectra based on grating geometry and complex permittivity.

  5. Role of bismuth in improving Helicobacter pylori eradication with triple therapy.

    PubMed

    Dore, Maria Pina; Lu, Hong; Graham, David Y

    2016-05-01

    In most regions of the world, antimicrobial resistance has increased to the point where empirical standard triple therapy for Helicobacter pylorieradication is no longer recommended. The treatment outcome in a population is calculated as the sum of the treatment success in the subpopulation with susceptible infections plus treatment success in the subpopulation with resistant infections. The addition of bismuth (i.e., 14-day triple therapy plus bismuth) can improve cure rates despite a high prevalence of antimicrobial resistance. The major bismuth effect is to add an additional 30%-40% to the success with resistant infections. The overall result is therefore dependent on the prevalence of resistance and the treatment success in the subpopulation with resistant infections (eg, with proton-pump inhibitor-amoxicillin dual therapy). Here, we explore the contribution of each component and the mechanisms of how bismuth might enhance the effectiveness of triple therapy. We also discuss the limitations of this approach and provide suggestions how triple therapy plus bismuth might be further improved. PMID:26848181

  6. Nonlinear optical properties of bismuth selenide

    NASA Astrophysics Data System (ADS)

    Bas, Derek; Babakiray, Sercan; Stanescu, Tudor; Lederman, David; Bristow, Alan

    Bismuth selenide (Bi2Se3) is a topological insulator with many interesting photonic properties. Much research has been done involving various types of photocurrents in an attempt to highlight the differences between the bulk electronic states and massless conducting surface states. Here, Bi2Se3 films varying in thickness from 6 to 40 quintuple layers have been produced via molecular beam epitaxy as a means to vary the relative contributions of bulk and surface. On these samples, optical measurements were performed at around 1.6 eV, which is enough energy to stimulate transitions from the Fermi level to a region near the second Dirac cone. Z-scan was used to measure saturable absorption, time-resolved two-color pump-probe was used to measure two-photon absorption, and a Fourier transform infrared spectrometer was used to measure linear absorption. Results were examined and analyzed with respect to thickness. Thickness-dependent band structures were produced using a tight-binding model and used to compare with experimental results.

  7. Gravimetric Analysis of Bismuth in Bismuth Subsalicylate Tablets: A Versatile Quantitative Experiment for Undergraduate Laboratories

    ERIC Educational Resources Information Center

    Davis, Eric; Cheung, Ken; Pauls, Steve; Dick, Jonathan; Roth, Elijah; Zalewski, Nicole; Veldhuizen, Christopher; Coeler, Joel

    2015-01-01

    In this laboratory experiment, lower- and upper-division students dissolved bismuth subsalicylate tablets in acid and precipitated the resultant Bi[superscript 3+] in solution with sodium phosphate for a gravimetric determination of bismuth subsalicylate in the tablets. With a labeled concentration of 262 mg/tablet, the combined data from three…

  8. Thermal degradation of ultrabroad bismuth NIR luminescence in bismuth-doped tantalum germanate laser glasses.

    PubMed

    Wang, Liping; Zhao, Yanqi; Xu, Shanhui; Peng, Mingying

    2016-04-01

    Because of ultra-broadband luminescence in 1000-1700 nm and consequent applications in fiber amplifier and lasers in the new spectral range where traditional rare earth cannot work, bismuth-doped laser glasses have received rising interest recently. For long-term practical application, thermal degradation must be considered for the glasses. This, however, has seldom been investigated. Here we report the thermal degradation of bismuth-doped germanate glass. Heating and cooling cycle experiments at high temperature reveal strong dependence of the thermal degradation on glass compositions. Bismuth and tantalum lead to the reversible degradation, while lithium can produce permanent irreversible degradation. The degradation becomes worse as lithium content increases in the glass. Absorption spectra show this is due to partial oxidation of bismuth near-infrared emission center. Surprisingly, we notice the emission of bismuth exhibits blueshift, rather than redshift at a higher temperature, and the blueshift can be suppressed by increasing the lithium content. PMID:27192231

  9. Airborne radioactive contamination monitoring

    SciTech Connect

    Whitley, C.R.; Adams, J.R.; Bounds, J.A.; MacArthur, D.W.

    1996-03-01

    Current technologies for the detection of airborne radioactive contamination do not provide real-time capability. Most of these techniques are based on the capture of particulate matter in air onto filters which are then processed in the laboratory; thus, the turnaround time for detection of contamination can be many days. To address this shortcoming, an effort is underway to adapt LRAD (Long-Range-Alpha-Detection) technology for real-time monitoring of airborne releases of alpa-emitting radionuclides. Alpha decays in air create ionization that can be subsequently collected on electrodes, producing a current that is proportional to the amount of radioactive material present. Using external fans on a pipe containing LRAD detectors, controlled samples of ambient air can be continuously tested for the presence of radioactive contamination. Current prototypes include a two-chamber model. Sampled air is drawn through a particulate filter and then through the first chamber, which uses an electrostatic filter at its entrance to remove ambient ionization. At its exit, ionization that occurred due to the presence of radon is collected and recorded. The air then passes through a length of pipe to allow some decay of short-lived radon species. A second chamber identical to the first monitors the remaining activity. Further development is necessary on air samples without the use of particulate filtering, both to distinguish ionization that can pass through the initial electrostatic filter on otherwise inert particulate matter from that produced through the decay of radioactive material and to separate both of these from the radon contribution. The end product could provide a sensitive, cost-effective, real-time method of determining the presence of airborne radioactive contamination.

  10. Bismuth alloy potting seals aluminum connector in cryogenic application

    NASA Technical Reports Server (NTRS)

    Flower, J. F.; Stafford, R. L.

    1966-01-01

    Bismuth alloy potting seals feedthrough electrical connector for instrumentation within a pressurized vessel filled with cryogenic liquids. The seal combines the transformation of high-bismuth content alloys with the thermal contraction of an external aluminum tube.

  11. Liquid Bismuth Propellant Flow Sensor

    NASA Technical Reports Server (NTRS)

    Polzin, Kurt A.; Stanojev, B. J.; Korman, V.

    2007-01-01

    Quantifying the propellant mass flow rate in liquid bismuth-fed electric propulsion systems has two challenging facets. First, the flow sensors must be capable of providing a resolvable measurement at propellant mass flow rates on the order of 10 mg/see with and uncertainty of less that 5%. The second challenge has to do with the fact that the materials from which the flow sensors are fabricated must be capable of resisting any of the corrosive effects associated with the high-temperature propellant. The measurement itself is necessary in order to properly assess the performance (thrust efficiency, Isp) of thruster systems in the laboratory environment. The hotspot sensor[I] has been designed to provide the bismuth propellant mass flow rate measurement. In the hotspot sensor, a pulse of thermal energy (derived from a current pulse and associated joule heating) is applied near the inlet of the sensor. The flow is "tagged" with a thermal feature that is convected downstream by the flowing liquid metal. Downstream, a temperature measurement is performed to detect a "ripple" in the local temperature associated with the passing "hotspot" in the propellant. By measuring the time between the upstream generation and downstream detection of the thermal feature, the flow speed can be calculated using a "time of flight" analysis. In addition, the system can be calibrated by measuring the accumulated mass exiting the system as a-function of time and correlating this with the time it takes the hotspot to convect through the sensor. The primary advantage of this technique is that it doesn't depend on an absolute measurement of temperature but, instead, relies on the observation of thermal features. This makes the technique insensitive to other externally generated thermal fluctuations. In this paper, we describe experiments performed using the hotspot flow sensor aimed at quantifying the resolution of the sensor technology. Propellant is expelled onto an electronic scale to

  12. Template synthesis of bismuth telluride nanowires. Interim report

    SciTech Connect

    Sapp, S.A.; Lakshmi, B.B.; Martin, C.R.

    1998-12-01

    The authors report the fabrication of thermoelectric bismuth telluride nanowires using the template synthesis method. A simple electrodeposition procedure was used to produce the nanowires within the pores of an alumina filtration membrane. The resulting bismuth telluride/alumina composite membranes constitute an array of thermoelectric nanowires surrounded by a thermally and electrically insulating matrix. The individual bismuth telluride nanowires can be isolated by removal of the template membrane. These nanowires were characterized and found to be composed of stoichiometric bismuth telluride.

  13. Modeling astatine production in liquid lead-bismuth spallation targets

    NASA Astrophysics Data System (ADS)

    David, J. C.; Boudard, A.; Cugnon, J.; Ghali, S.; Leray, S.; Mancusi, D.; Zanini, L.

    2013-03-01

    Astatine isotopes can be produced in liquid lead-bismuth eutectic targets through proton-induced double charge exchange reactions on bismuth or in secondary helium-induced interactions. Models implemented into the most common high-energy transport codes generally have difficulties to correctly estimate their production yields as was shown recently by the ISOLDE Collaboration, which measured release rates from a lead-bismuth target irradiated by 1.4 and 1 GeV protons. In this paper, we first study the capability of the new version of the Liège intranuclear cascade model, INCL4.6, coupled to the deexcitation code ABLA07 to predict the different elementary reactions involved in the production of such isotopes through a detailed comparison of the model with the available experimental data from the literature. Although a few remaining deficiencies are identified, very satisfactory results are found, thanks in particular to improvements brought recently on the treatment of low-energy helium-induced reactions. The implementation of the models into MCNPX allows identifying the respective contributions of the different possible reaction channels in the ISOLDE case. Finally, the full simulation of the ISOLDE experiment is performed, taking into account the likely rather long diffusion time from the target, and compared with the measured diffusion rates for the different astatine isotopes, at the two studied energies, 1.4 and 1 GeV. The shape of the isotopic distribution is perfectly reproduced as well as the absolute release rates, assuming in the calculation a diffusion time between 5 and 10hours. This work finally shows that our model, thanks to the attention paid to the emission of high-energy clusters and to low-energy cluster induced reactions, can be safely used within MCNPX to predict isotopes with a charge larger than that of the target by two units in spallation targets, and, probably, more generally to isotopes created in secondary reactions induced by composite

  14. Electrodeposition and Characterization of Bismuth Telluride Nanowires

    NASA Astrophysics Data System (ADS)

    Frantz, C.; Stein, N.; Gravier, L.; Granville, S.; Boulanger, C.

    2010-09-01

    In this work, we report thermoelectric measurements on electroplated bismuth telluride nanowires. Porous polycarbonate membranes, obtained by ion-track irradiation lithography, were chosen as electroplating templates. Bismuth telluride nanowires were achieved in acidic media under potentiostatic conditions at -100 mV versus saturated silver chloride electrode. The filling ratio of the pores was increased to 80% by adding dimethyl sulfoxide to the electrolyte. Whatever the experimental conditions, the nanowires were polycrystalline in the rhombohedral phase of Bi2Te3. Finally, the power output of arrays of bismuth telluride nanowires was analyzed as a function of load resistance. The results were strongly dependent on the internal resistance, which can be significantly reduced by the presence of dimethyl sulfoxide during electroplating.

  15. Liquid Bismuth Feed System for Electric Propulsion

    NASA Technical Reports Server (NTRS)

    Markusic, T. E.; Polzin, K. A.; Stanojev, B. J.

    2006-01-01

    Operation of Hall thrusters with bismuth propellant has been shown to be a promising path toward high-power, high-performance, long-lifetime electric propulsion for spaceflight missions. For example, the VHITAL project aims td accurately, experimentally assess the performance characteristics of 10 kW-class bismuth-fed Hall thrusters - in order to validate earlier results and resuscitate a promising technology that has been relatively dormant for about two decades. A critical element of these tests will be the precise metering of propellant to the thruster, since performance cannot be accurately assessed without an accurate accounting of mass flow rate. Earlier work used a pre/post-test propellant weighing scheme that did not provide any real-time measurement of mass flow rate while the thruster was firing, and makes subsequent performance calculations difficult. The motivation of the present work was to develop a precision liquid bismuth Propellant Management System (PMS) that provides real-time propellant mass flow rate measurement and control, enabling accurate thruster performance measurements. Additionally, our approach emphasizes the development of new liquid metal flow control components and, hence, will establish a basis for the future development of components for application in spaceflight. The design of various critical components in a bismuth PMS are described - reservoir, electromagnetic pump, hotspot flow sensor, and automated control system. Particular emphasis is given to material selection and high-temperature sealing techniques. Open loop calibration test results are reported, which validate the systems capability to deliver bismuth at mass flow rates ranging from 10 to 100 mg/sec with an uncertainty of less than +/- 5%. Results of integrated vaporizer/liquid PMS tests demonstrate all of the necessary elements of a complete bismuth feed system for electric propulsion.

  16. Burnout current density of bismuth nanowires

    NASA Astrophysics Data System (ADS)

    Cornelius, T. W.; Picht, O.; Müller, S.; Neumann, R.; Völklein, F.; Karim, S.; Duan, J. L.

    2008-05-01

    Single bismuth nanowires with diameters ranging from 100nmto1μm were electrochemically deposited in ion track-etched single-pore polycarbonate membranes. The maximum current density the wires are able to carry was investigated by ramping up the current until failure occurred. It increases by three to four orders of magnitude for nanowires embedded in the template compared to bulk bismuth and rises with diminishing diameter. Simulations show that the wires are heated up electrically to the melting temperature. Since the surface-to-volume ratio rises with diminishing diameter, thinner wires dissipate the heat more efficiently to the surrounding polymer matrix and, thus, can tolerate larger current densities.

  17. Field-induced polarization of Dirac valleys in bismuth

    NASA Astrophysics Data System (ADS)

    Behnia, Kamran; Zhu, Zengwei; Callaudin, Aurelie; Fauque, Benoit; Kang, Woun

    2012-02-01

    The principal challenge in the field of ``valleytronics'' is to lift the valley degeneracy of electrons in a controlled way. In graphene, a number of methods to generate a valley-polarized flow of electrons have been proposed, which are yet to be experimentally realized. In bulk semi-metallic bismuth, the Fermi surface includes three cigar-shaped electron valleys lying almost perpendicular to the high-symmetry axis known as the trigonal axis. The in-plane mass anisotropy of each valley exceeds 200 as a consequence of Dirac dispersion, which drastically reduces the effective mass along two out of the three orientations. We present a study of angle-dependent magnetoresistance in bismuth which shows that a flow of Dirac electrons along the trigonal axis is extremely sensitive to the orientation of in-plane magnetic field. The effect is visible even at room temperature. Thus, a rotatable magnetic field can be used as a valley valve to tune the contribution of each valley to the total conductivity. At high temperature and low magnetic field, the three valleys are interchangeable and the three-fold symmetry of the underlying lattice is respected. As the temperature is decreased or the magnetic field increased, this symmetry is spontaneously lost. This loss may be an experimental manifestation of the recently proposed valley-nematic Fermi liquid state.

  18. Metabolism of bismuth subsalicylate and intracellular accumulation of bismuth by Fusarium sp. strain BI.

    PubMed

    Dodge, Anthony G; Wackett, Lawrence P

    2005-02-01

    Enrichment cultures were conducted using bismuth subsalicylate as the sole source of carbon and activated sludge as the inoculum. A pure culture was obtained and identified as a Fusarium sp. based on spore morphology and partial sequences of 18S rRNA, translation elongation factor 1-alpha, and beta-tubulin genes. The isolate, named Fusarium sp. strain BI, grew to equivalent densities when using salicylate or bismuth subsalicylate as carbon sources. Bismuth nitrate at concentrations of up to 200 muM did not limit growth of this organism on glucose. The concentration of soluble bismuth in suspensions of bismuth subsalicylate decreased during growth of Fusarium sp. strain BI. Transmission electron microscopy and energy-dispersive spectroscopy revealed that the accumulated bismuth was localized in phosphorus-rich granules distributed in the cytoplasm and vacuoles. Long-chain polyphosphates were extracted from fresh biomass grown on bismuth subsalicylate, and inductively coupled plasma optical emission spectrometry showed that these fractions also contained high concentrations of bismuth. Enzyme activity assays of crude extracts of Fusarium sp. strain BI showed that salicylate hydroxylase and catechol 1,2-dioxygenase were induced during growth on salicylate, indicating that this organism degrades salicylate by conversion of salicylate to catechol, followed by ortho cleavage of the aromatic ring. Catechol 2,3-dioxygenase activity was not detected. Fusarium sp. strain BI grew with several other aromatic acids as carbon sources: benzoate, 3-hydroxybenzoate, 4-hydroxybenzoate, gentisate, d-mandelate, l-phenylalanine, l-tyrosine, phenylacetate, 3-hydroxyphenylacetate, 4-hydroxyphenylacetate, and phenylpropionate. PMID:15691943

  19. Probing bismuth ferrite nanoparticles by hard x-ray photoemission: Anomalous occurrence of metallic bismuth

    SciTech Connect

    Chaturvedi, Smita; Rajendra, Ranguwar; Ballav, Nirmalya; Kulkarni, Sulabha; Sarkar, Indranil; Shirolkar, Mandar M.; Jeng, U-Ser; Yeh, Yi-Qi

    2014-09-08

    We have investigated bismuth ferrite nanoparticles (∼75 nm and ∼155 nm) synthesized by a chemical method, using soft X-ray (1253.6 eV) and hard X-ray (3500, 5500, and 7500 eV) photoelectron spectroscopy. This provided an evidence for the variation of chemical state of bismuth in crystalline, phase pure nanoparticles. X-ray photoelectron spectroscopy analysis using Mg Kα (1253.6 eV) source showed that iron and bismuth were present in both Fe{sup 3+} and Bi{sup 3+} valence states as expected for bismuth ferrite. However, hard X-ray photoelectron spectroscopy analysis of the bismuth ferrite nanoparticles using variable photon energies unexpectedly showed the presence of Bi{sup 0} valence state below the surface region, indicating that bismuth ferrite nanoparticles are chemically inhomogeneous in the radial direction. Consistently, small-angle X-ray scattering reveals a core-shell structure for these radial inhomogeneous nanoparticles.

  20. Hydrothermal synthesis map of bismuth titanates

    NASA Astrophysics Data System (ADS)

    Sardar, Kripasindhu; Walton, Richard I.

    2012-05-01

    The hydrothermal synthesis of four bismuth titanate materials from common bismuth and titanium precursors under hydrothermal conditions is described. Reaction of NaBiO3·2H2O and anatase TiO2 in concentrated NaOH solution at 240 °C is shown to produce perovskite and sillenite phases Na0.5Bi0.5TiO3 and Bi12TiO20, depending on the ratio of metal precursors used. When KOH solution is used and a 1:1 ratio of the same precursors, a pyrochlore Bi1.43Ti2O6(OH)0.29(H2O)0.66 is formed. The use of a mixture of HNO3 and NaOH is shown to facilitate the formation of the Aurivillius-type bismuth titanate Bi4Ti3O12. The phases have been isolated separately as phase-pure powders and profile refinement of powder X-ray diffraction data allows comparisons with comparable materials reported in the literature. Analysis of Bi LIII-edge X-ray absorption near edge structure (XANES) spectra of the materials shows the oxidation state of bismuth is +3 in all of the hydrothermally derived products.

  1. Hydrothermal synthesis map of bismuth titanates

    SciTech Connect

    Sardar, Kripasindhu; Walton, Richard I.

    2012-05-15

    The hydrothermal synthesis of four bismuth titanate materials from common bismuth and titanium precursors under hydrothermal conditions is described. Reaction of NaBiO{sub 3}{center_dot}2H{sub 2}O and anatase TiO{sub 2} in concentrated NaOH solution at 240 Degree-Sign C is shown to produce perovskite and sillenite phases Na{sub 0.5}Bi{sub 0.5}TiO{sub 3} and Bi{sub 12}TiO{sub 20}, depending on the ratio of metal precursors used. When KOH solution is used and a 1:1 ratio of the same precursors, a pyrochlore Bi{sub 1.43}Ti{sub 2}O{sub 6}(OH){sub 0.29}(H{sub 2}O){sub 0.66} is formed. The use of a mixture of HNO{sub 3} and NaOH is shown to facilitate the formation of the Aurivillius-type bismuth titanate Bi{sub 4}Ti{sub 3}O{sub 12}. The phases have been isolated separately as phase-pure powders and profile refinement of powder X-ray diffraction data allows comparisons with comparable materials reported in the literature. Analysis of Bi L{sub III}-edge X-ray absorption near edge structure (XANES) spectra of the materials shows the oxidation state of bismuth is +3 in all of the hydrothermally derived products. - Graphical abstract: Use of NaBiO{sub 3}{center_dot}2H{sub 2}O and TiO{sub 2} as reagents under hydrothermal conditions allows the phase-pure preparation of four crystalline bismuth titanate materials. Highlights: Black-Right-Pointing-Pointer NaBiO{sub 3} and TiO{sub 2} under hydrothermal conditions allow formation of bismuth titanates. Black-Right-Pointing-Pointer Synthesis of four distint phases has been mapped. Black-Right-Pointing-Pointer Bi LIII-edge XANES shows Bi is reduced to oxidation state +3 in all materials. Black-Right-Pointing-Pointer A new hydrated bismuth titanate pyrochlore has been isolated.

  2. Bismuth pyrochlore thin films for dielectric energy storage

    SciTech Connect

    Michael, Elizabeth K. Trolier-McKinstry, Susan

    2015-08-07

    Thin films of cubic pyrochlore bismuth zinc niobate, bismuth zinc tantalate, and bismuth zinc niobate tantalate were fabricated using chemical solution deposition. This family of materials exhibited moderate relative permittivities between 55 ± 2 and 145 ± 5 for bismuth zinc tantalate and bismuth zinc niobate, respectively, and low loss tangents on the order of 0.0008 ± 0.0001. Increases in the concentration of the tantalum end member increased the dielectric breakdown strength. For example, at 10 kHz, the room temperature breakdown strength of bismuth zinc niobate was 5.1 MV/cm, while that of bismuth zinc tantalate was 6.1 MV/cm. This combination of a high breakdown strength and a moderate permittivity led to a high discharged energy storage density for all film compositions. For example, at a measurement frequency of 10 kHz, bismuth zinc niobate exhibited a maximum recoverable energy storage density of 60.8 ± 2.0 J/cm{sup 3}, while bismuth zinc tantalate exhibited a recoverable energy storage density of 60.7 ± 2.0 J/cm{sup 3}. Intermediate compositions of bismuth zinc niobate tantalate offered higher energy storage densities; at 10 mol. % tantalum, the maximum recoverable energy storage density was ∼66.9 ± 2.4 J/cm{sup 3}.

  3. Airborne oceanographic lidar system

    NASA Technical Reports Server (NTRS)

    Bressel, C.; Itzkan, I.; Nunes, J. E.; Hoge, F.

    1977-01-01

    The characteristics of an Airborne Oceanographic Lidar (AOL) are given. The AOL system is described and its potential for various measurement applications including bathymetry and fluorosensing is discussed.

  4. Nanoscale mechanisms for the reduction of heat transport in bismuth

    NASA Astrophysics Data System (ADS)

    Markov, Maxime; Sjakste, Jelena; Fugallo, Giorgia; Paulatto, Lorenzo; Lazzeri, Michele; Mauri, Francesco; Vast, Nathalie

    2016-02-01

    Hand-on routes to reduce lattice thermal conductivity (LTC) in bismuth have been explored by employing a combination of Boltzmann's transport equation and ab initio calculations of phonon-phonon interaction within the density functional perturbation theory. We have first obtained the temperature dependence of the bulk LTC in excellent agreement with available experiments. A very accurate microscopic description of heat transport has been achieved and the electronic contribution to thermal conductivity has been determined. By controlling the interplay between phonon-phonon interaction and phonon scattering by sample boundaries, we predict the effect of size reduction for various temperatures and nanostructure shapes. The largest heat transport reduction is obtained in polycrystals with grain sizes smaller than 100 nm.

  5. Bound excitons at nitrogen and bismuth isoelectronic impurities

    NASA Astrophysics Data System (ADS)

    Christian, Theresa; Alberi, Kirstin; Beaton, Daniel; Fluegel, Brian; Mascarenhas, Angelo

    When nitrogen and bismuth dopants are simultaneously incorporated into a host lattice such as gallium arsenide (GaAs) or gallium phosphide (GaP), each dopant species contributes to the evolution of the electronic structure. Bound excitons in these systems luminescence from localized states whose distinctive radiative signatures provide invaluable clues into the nature of impurity clustering and inter-impurity interactions within the host lattice. Spectroscopic studies of these states will be presented for a series of samples grown by molecular beam epitaxy. Research was supported by the U. S. Department of Energy, Basic Energy Sciences, Materials Sciences and Engineering Division under contract DE-AC36-08GO28308 and by the Department of Energy Office of Science Graduate Fellowship Program (DOE SCGF), made possible in part by the American Recovery and Reinvestment Act of 2009, administered by ORISE-ORAU under Contract No. DE-AC05-06OR23100.

  6. Spectrally resolved optical probing of laser induced magnetization dynamics in bismuth iron garnet

    NASA Astrophysics Data System (ADS)

    Koene, Benny; Deb, Marwan; Popova, Elena; Keller, Niels; Rasing, Theo; Kirilyuk, Andrei

    2016-07-01

    The spectrally resolved magnetization dynamics in bismuth iron garnet shows a fluence dependent light induced modification of the magneto-optical Faraday spectrum. It is demonstrated that the relative contributions from the tetrahedral and octahedral iron sites to the Faraday spectrum change due to the impact of the pump pulse. This change explains the observed deviation from a linear dependence of the amplitude of the oscillations on the fluence, as expected for the inverse Faraday effect.

  7. Spectrally resolved optical probing of laser induced magnetization dynamics in bismuth iron garnet.

    PubMed

    Koene, Benny; Deb, Marwan; Popova, Elena; Keller, Niels; Rasing, Theo; Kirilyuk, Andrei

    2016-07-13

    The spectrally resolved magnetization dynamics in bismuth iron garnet shows a fluence dependent light induced modification of the magneto-optical Faraday spectrum. It is demonstrated that the relative contributions from the tetrahedral and octahedral iron sites to the Faraday spectrum change due to the impact of the pump pulse. This change explains the observed deviation from a linear dependence of the amplitude of the oscillations on the fluence, as expected for the inverse Faraday effect. PMID:27213266

  8. Magnetoconductance fluctuations in open bismuth quantum dots

    NASA Astrophysics Data System (ADS)

    Hackens, B.; Minet, J. P.; Farhi, G.; Crahay, A.; Faniel, S.; Gustin, C.; Bayot, V.

    2002-03-01

    We investigate the low temperature (300 mK - 10 K) magnetoconductance of open circular bismuth quantum dots (diameter: 500 nm). The structures are fabricated using a combination of electron beam lithography, lift off and plasma etching techniques on bismuth thin films evaporated on heated SiO2 substrates. We observe reproducible magnetoconductance fluctuations (UCFs) up to 5T, qualitatively similar to conductance fluctuations evidenced in open quantum dots patterned in high mobility semiconductor heterostructures. In our samples, UCFs are superposed on a slowly varying negative magnetoconductance background. We also observe a sharp conductance maximum centered in B=0, which is reminescent of the spin-orbit induced anti-localisation phenomenon. The behavior of UCFs and of the conductance maximum is discussed as a function of the temperature, thickness and degree of cristallinity of the cavity.

  9. Phase transitions of Dirac electrons in bismuth.

    PubMed

    Li, Lu; Checkelsky, J G; Hor, Y S; Uher, C; Hebard, A F; Cava, R J; Ong, N P

    2008-07-25

    The Dirac Hamiltonian, which successfully describes relativistic fermions, applies equally well to electrons in solids with linear energy dispersion, for example, in bismuth and graphene. A characteristic of these materials is that a magnetic field less than 10 tesla suffices to force the Dirac electrons into the lowest Landau level, with resultant strong enhancement of the Coulomb interaction energy. Moreover, the Dirac electrons usually come with multiple flavors or valley degeneracy. These ingredients favor transitions to a collective state with novel quantum properties in large field. By using torque magnetometry, we have investigated the magnetization of bismuth to fields of 31 tesla. We report the observation of sharp field-induced phase transitions into a state with striking magnetic anisotropy, consistent with the breaking of the threefold valley degeneracy. PMID:18653888

  10. Stress-driven growth of bismuth nanowires

    NASA Astrophysics Data System (ADS)

    Cheng, Yang-Tse; Weiner, Anita M.; Wong, Curtis A.; Balogh, Michael P.; Lukitsch, Michael J.

    2003-03-01

    We recently reported that compressive stresses in thin films can be exploited to grow nanowires (Ref.1). Nanowires of bismuth (Bi) with diameters ranging from 30 to 200 nm and lengths up to several millimeters were formed spontaneously at the rate of a few micrometers per second at room temperature on surfaces of freshly grown composite thin films consisting of Bi and chrome-nitride (CrN). The high compressive stress in the composite thin films was shown to be the driving force responsible for the nanowire formation. In this presentation, the effects of stress, composition, and temperature on the growth and structure of bismuth nanowires will be discussed. This method of growing nanowires can also be extended to other material systems. Ref. 1. Yang-Tse Cheng, Anita M. Weiner, Curtis A. Wong, Michael P. Balogh, and Michael J. Lukitsch, Applied Physics Letters 81, 3248 (2002).

  11. Bismuth film electrodes for heavy metals determination

    NASA Astrophysics Data System (ADS)

    Rehacek, Vlastimil; Hotovy, Ivan; Vojs, Marian; Mika, Fedor

    2007-05-01

    Bismuth film electrodes (BiFEs) have a potential to replace toxic mercury used most frequently for determination of heavy metals (Cd, Pb, Zn) by anodic stripping voltammetry. We prepared a graphite disc electrode (0.5 mm in diameter) from a pencil-lead rod and developed a nitrogen doped diamond-like carbon (NDLC) microelectrode array consisting of 50 625 microdiscs with 3 μm in diameter and interelectrode distances of 20 μm on a highly conductive silicon substrate as a support for BiFEs. The disc graphite BiFE was used for simultaneous determination of Pb(II), Cd(II) and Zn(II) by square wave voltammetry (SWV) in an aqueous solution. We found the optimum bismuth-to-metal concentration ratio in the solution to be 20. The dependence of the stripping responses on the concentration of target metals was linear in the range from 1×10 -8 to 1.2×10 -7 mol/L. Detection limits 2.4×10 -9 mol/L for Pb(II), 2.9×10 -9 mol/L for Cd(II) and 1.2×10 -8 mol/L for Zn(II) were estimated. A bismuth-plated NDLC microelectrode array was used for Pb(II) determination by differential pulse voltammetry (DPV) in an aqueous solution. We found that the stripping current for bismuth-plated NDLC array was linear in the concentration range of Pb(II) from 2×10 -8 to 1.2×10 -7 mol/L. The detection limit 2.2×10 -8 mol/L was estimated from a calibration plot.

  12. Ultrafast broadband spectroscopy of crystalline bismuth

    SciTech Connect

    Mel'nikov, A A; Misochko, Oleg V; Chekalin, Sergei V

    2013-04-30

    Femtosecond spectroscopy in the wavelength range 0.4 - 2.3 {mu}m has been used to probe ultrafast electronic and lattice processes in bismuth. The photoresponse of a bismuth crystal is shown to comprise components with relaxation times of 1 ps, 7 ps, and {approx}1 ns. The electron-hole and electron-phonon interaction strengths in bismuth are found to depend significantly on the wave vector in the {Gamma}-T direction of the Brillouin zone. Comparison of the spectral dependences of the amplitudes of coherent E{sub g} and A{sub 1g} phonons and the corresponding dependences of the Raman scattering cross sections indicates that these phonon modes differ in generation mechanism. The generation of coherent A{sub 1g} phonons is mainly due to displacement of the equilibrium position of atoms in the crystal lattice in a nonequilibrium state. This process differs fundamentally from resonance Raman scattering responsible for the coherent excitation of low-symmetry phonon modes. (extreme light fields and their applications)

  13. Spin dynamics of complex oxides, bismuth-antimony alloys, and bismuth chalcogenides

    NASA Astrophysics Data System (ADS)

    Sahin, Cuneyt

    The emerging field of spintronics relies on the manipulation of electron spin in order to use it in spin-based electronics. Such a paradigm change has to tackle several challenges including finding materials with sufficiently long spin lifetimes and materials which are efficient in generating pure spin currents. This thesis predicts that two types of material families could be a solution to the aforementioned challenges: complex oxides and bismuth based materials. We derived a general approach for constructing an effective spin-orbit Hamiltonian which is applicable to all nonmagnetic materials. This formalism is useful for calculating spin-dependent properties near an arbitrary point in momentum space. We also verified this formalism through comparisons with other approaches for III-V semiconductors, and its general applicability is illustrated by deriving the spin-orbit interaction and predicting spin lifetimes for strained strontium titanate (STO) and a two-dimensional electron gas in STO (such as at the LAO/STO interface). Our results suggest robust spin coherence and spin transport properties in STO related materials even at room temperature. In the second part of the study we calculated intrinsic spin Hall conductivities for bismuth-antimony (BISb) semimetals with strong spin-orbit couplings, from the Kubo formula and using Berry curvatures evaluated throughout the Brillouin zone from a tight-binding Hamiltonian. Nearly crossing bands with strong spin-orbit interaction generate giant spin Hall conductivities in these materials, ranging from 474 ((h/e)O--1cm--1) for bismuth to 96((h/e)O--1cm --1) for antimony; the value for bismuth is more than twice that of platinum. The large spin Hall conductivities persist for alloy compositions corresponding to a three-dimensional topological insulator state, such as Bi0.83Sb0.17. The spin Hall conductivity could be changed by a factor of 5 for doped Bi, or for Bi0.83Sb0.17, by changing the chemical potential by 0.5 e

  14. Airborne GLM Simulator (FEGS)

    NASA Astrophysics Data System (ADS)

    Quick, M.; Blakeslee, R. J.; Christian, H. J., Jr.; Stewart, M. F.; Podgorny, S.; Corredor, D.

    2015-12-01

    Real time lightning observations have proven to be useful for advanced warning and now-casting of severe weather events. In anticipation of the launch of the Geostationary Lightning Mapper (GLM) onboard GOES-R that will provide continuous real time observations of total (both cloud and ground) lightning, the Fly's Eye GLM Simulator (FEGS) is in production. FEGS is an airborne instrument designed to provide cal/val measurements for GLM from high altitude aircraft. It consists of a 5 x 5 array of telescopes each with a narrow passband filter to isolate the 777.4 nm neutral oxygen emission triplet radiated by lightning. The telescopes will measure the optical radiance emitted by lightning that is transmitted through the cloud top with a temporal resolution of 10 μs. When integrated on the NASA ER-2 aircraft, the FEGS array with its 90° field-of-view will observe a cloud top area nearly equal to a single GLM pixel. This design will allow FEGS to determine the temporal and spatial variation of light that contributes to a GLM event detection. In addition to the primary telescope array, the instrument includes 5 supplementary optical channels that observe alternate spectral emission features and will enable the use of FEGS for interesting lightning physics applications. Here we present an up-to-date summary of the project and a description of its scientific applications.

  15. Binding and killing of bacteria by bismuth subsalicylate.

    PubMed Central

    Sox, T E; Olson, C A

    1989-01-01

    Bismuth subsalicylate (BSS) is a compound without significant aqueous solubility that is widely used for the treatment of gastrointestinal disorders. BSS was able to bind bacteria of diverse species, and these bound bacteria were subsequently killed. A 4-log10 reduction of viable bacteria occurred within 4 h after a 10 mM aqueous suspension of BSS was inoculated with 2 x 10(6) Escherichia coli cells per ml. Binding and killing were dependent on the levels of inoculated bacteria, and significant binding but little killing of the exposed bacteria occurred at an inoculum level of 2 x 10(9) E. coli per ml. Intracellular ATP decreased rapidly after exposure of E. coli to 10 mM BSS and, after 30 min, was only 1% of the original level. Extracellular ATP increased after exposure to BSS, but the accumulation of extracellular ATP was not sufficient to account for the loss of intracellular ATP. The killing of bacteria exposed to BSS may have been due to cessation of ATP synthesis or a loss of membrane integrity. Bactericidal activity of BSS was also investigated in a simulated gastric juice at pH 3. Killing of E. coli at this pH was much more rapid than at pH 7 and was apparently due to salicylate released by the conversion of BSS to bismuth oxychloride. It is proposed that the binding and killing observed for BSS contribute to the efficacy of this compound against gastrointestinal infections such as traveler's diarrhea. PMID:2694949

  16. Shubnikov-de Haas Oscillations in Single-Crystal Bismuth Nanowires Encased in Quartz Template

    NASA Astrophysics Data System (ADS)

    Tsunemi, Fumiaki; Murata, Masayuki; Saito, Yusuke; Shirota, Katsuhito; Hasegawa, Yasuhiro; Komine, Takashi

    2013-04-01

    Shubnikov-de Haas (SdH) oscillations were measured at 0.3 K in bismuth nanowires with diameters of 393, 548, and 622 nm, and lengths of over 1 mm, which were encased in quartz templates. The magnetoresistance was measured up to a magnetic field of 17 T. Distinct SdH oscillations were observed, and the nanowire samples were rotated in the magnetic field to determine the contribution due to holes, electrons, and spin-orbit interactions. For the 622-nm-diameter nanowire, for example, values of 30.7 meV and 1.66×1017 cm-3 were obtained for the Fermi energy and carrier density, respectively, which were similar to the values for bulk bismuth.

  17. Airborne gravity is here

    SciTech Connect

    Hammer, S.

    1982-01-11

    After 20 years of development efforts, the airborne gravity survey has finally become a practical exploration method. Besides gravity data, the airborne survey can also collect simultaneous, continuous records of high-precision magneticfield data as well as terrain clearance; these provide a topographic contour map useful in calculating terrain conditions and in subsequent planning and engineering. Compared with a seismic survey, the airborne gravity method can cover the same area much more quickly and cheaply; a seismograph could then detail the interesting spots.

  18. Hall-Effect Thruster Utilizing Bismuth as Propellant

    NASA Technical Reports Server (NTRS)

    Szabo, James; Gasdaska, Charles; Hruby, Vlad; Robin, Mike

    2008-01-01

    A laboratory-model Hall-effect spacecraft thruster was developed that utilizes bismuth as the propellant. Xenon was used in most prior Hall-effect thrusters. Bismuth is an attractive alternative because it has a larger atomic mass, a larger electron-impact-ionization cross-section, and is cheaper and more plentiful.

  19. 21 CFR 520.1204 - Kanamycin, bismuth subcarbonate, activated attapulgite.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Kanamycin, bismuth subcarbonate, activated... § 520.1204 Kanamycin, bismuth subcarbonate, activated attapulgite. (a) Specifications—(1) Each 5 milliliters (mL) of suspension contains 100 milligrams (mg) kanamycin (as the sulfate), 250 mg...

  20. 21 CFR 520.1204 - Kanamycin, bismuth subcarbonate, activated attapulgite.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Kanamycin, bismuth subcarbonate, activated... § 520.1204 Kanamycin, bismuth subcarbonate, activated attapulgite. (a) Specifications—(1) Each 5 milliliters (mL) of suspension contains 100 milligrams (mg) kanamycin (as the sulfate), 250 mg...

  1. 21 CFR 520.1204 - Kanamycin, bismuth subcarbonate, activated attapulgite.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 6 2014-04-01 2014-04-01 false Kanamycin, bismuth subcarbonate, activated... § 520.1204 Kanamycin, bismuth subcarbonate, activated attapulgite. (a) Specifications—(1) Each 5 milliliters (mL) of suspension contains 100 milligrams (mg) kanamycin (as the sulfate), 250 mg...

  2. 21 CFR 520.1204 - Kanamycin, bismuth subcarbonate, activated attapulgite.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Kanamycin, bismuth subcarbonate, activated... § 520.1204 Kanamycin, bismuth subcarbonate, activated attapulgite. (a) Specifications—(1) Each 5 milliliters (mL) of suspension contains 100 milligrams (mg) kanamycin (as the sulfate), 250 mg...

  3. 21 CFR 520.1204 - Kanamycin, bismuth subcarbonate, activated attapulgite.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 6 2013-04-01 2013-04-01 false Kanamycin, bismuth subcarbonate, activated... § 520.1204 Kanamycin, bismuth subcarbonate, activated attapulgite. (a) Specifications—(1) Each 5 milliliters (mL) of suspension contains 100 milligrams (mg) kanamycin (as the sulfate), 250 mg...

  4. Bismuth(III) dialkyldithiophosphates: Facile single source precursors for the preparation of bismuth sulfide nanorods and bismuth phosphate thin films

    SciTech Connect

    Biswal, Jasmine B.; Garje, Shivram S.; Nuwad, Jitendra; Pillai, C.G.S.

    2013-08-15

    Two different phase pure materials (Bi{sub 2}S{sub 3} and Bi{sub 2}P{sub 4}O{sub 13}) have been prepared under different conditions using the same single source precursors. Solvothermal decomposition of the complexes, Bi(S{sub 2}P(OR){sub 2}){sub 3} [where, R=Methyl (Me) (1), Ethyl (Et) (2), n-Propyl (Pr{sup n}) (3) and iso-Propyl (Pr{sup i}) (4)] in ethylene glycol gave orthorhombic bismuth sulfide nanorods, whereas aerosol assisted chemical vapor deposition (AACVD) of the same precursors deposited monoclinic bismuth tetraphosphate (Bi{sub 2}P{sub 4}O{sub 13}) thin films on glass substrates. Surface study of the thin films using SEM illustrated the formation of variety of nanoscale morphologies (spherical-, wire-, pendent-, doughnut- and flower-like) at different temperatures. AFM studies were carried out to evaluate quality of the films in terms of uniformity and roughness. Thin films of average roughness as low as 1.4 nm were deposited using these precursors. Photoluminescence studies of Bi{sub 2}P{sub 4}O{sub 13} thin films were also carried out. - Graphical abstract: Solvothermal decomposition of bismuth(III) dialkyldithiophosphates in ethylene glycol gave Bi{sub 2}S{sub 3} nanoparticles, whereas aerosol assisted chemical vapor deposition of these single source precursors deposited Bi{sub 2}P{sub 4}O{sub 13} thin films. Display Omitted - Highlights: • Preparation of phase pure orthorhombic Bi{sub 2}S{sub 3} nanorods and monoclinic Bi{sub 2}P{sub 4}O{sub 13} thin films. • Use of single source precursors for deposition of bismuth phosphate thin films. • Use of solvothermal decomposition and AACVD methods. • Morphology controlled synthesis of Bi{sub 2}P{sub 4}O{sub 13} thin films. • Bi{sub 2}S{sub 3} nanorods and Bi{sub 2}P{sub 4}O{sub 13} thin films using same single source precursors.

  5. Heat capacity, enthalpy and entropy of bismuth niobate and bismuth tantalate

    SciTech Connect

    Hampl, M.; Strejc, A.; Sedmidubsky, D.; Ruzicka, K.; Hejtmanek, J.; Leitner, J. . E-mail: jindrich.leitner@vscht.cz

    2006-01-15

    The heat capacity and the heat content of bismuth niobate BiNbO{sub 4} and bismuth tantalate BiTaO{sub 4} were measured by the relaxation method and Calvet-type heat flux calorimetry. The temperature dependencies of the heat capacities in the form C{sub p} {sub m}=128.628+0.03340 T-1991055/T {sup 2}+136273131/T {sup 3} (J K{sup -1} mol{sup -1}) and 133.594+0.02539 T-2734386/T {sup 2}+235597393/T {sup 3} (J K{sup -1} mol{sup -1}) were derived for BiNbO{sub 4} and BiTaO{sub 4}, respectively, by the least-squares method from the experimental data. Furthermore, the standard molar entropies at 298.15 K S {sub m}(BiNbO{sub 4})=147.86 J K{sup -1} mol{sup -1} and S {sub m}(BiTaO{sub 4})=149.11 J K{sup -1} mol{sup -1} were assessed from the low temperature heat capacity measurements. To complete a set of thermodynamic data of these mixed oxides an attempt was made to estimate the values of the heat of formation from the constituent binary oxides. -- Graphical abstract: Heat content of bismuth niobate and bismuth tantalate-experimental points determined by the drop method and temperature dependencies obtained by the simultaneous fit of heat capacity and heat content data.

  6. Toolsets for Airborne Data

    Atmospheric Science Data Center

    2015-04-02

    article title:  Toolsets for Airborne Data     View larger image The ... limit of detection values. Prior to accessing the TAD Web Application ( https://tad.larc.nasa.gov ) for the first time, users must ...

  7. The airborne laser

    NASA Astrophysics Data System (ADS)

    Lamberson, Steven; Schall, Harold; Shattuck, Paul

    2007-05-01

    The Airborne Laser (ABL) is an airborne, megawatt-class laser system with a state-of-the-art atmospheric compensation system to destroy enemy ballistic missiles at long ranges. This system will provide both deterrence and defense against the use of such weapons during conflicts. This paper provides an overview of the ABL weapon system including: the notional operational concept, the development approach and schedule, the overall aircraft configuration, the technologies being incorporated in the ABL, and the current program status.

  8. Bismuth-based perovskites as multiferroics

    NASA Astrophysics Data System (ADS)

    Guennou, Mael; Viret, Michel; Kreisel, Jens

    2015-03-01

    This review devoted to multiferroic properties of bismuth-based perovskites is divided into two parts. The first one focuses on BiFeO3 and summarizes the recent progress made in the studies of its pressure-temperature phase diagram and magnetoelectric coupling phenomena. The second part discusses in a more general way the issue of polar-and multiferroic-phases in Bi BO3 perovskites and the competition between ferroelectricity and other structural instabilities, from an inventory of recently synthesized compounds.

  9. Deterministic Switching in Bismuth Ferrite Nanoislands.

    PubMed

    Morelli, Alessio; Johann, Florian; Burns, Stuart R; Douglas, Alan; Gregg, J Marty

    2016-08-10

    We report deterministic selection of polarization variant in bismuth BiFeO3 nanoislands via a two-step scanning probe microscopy procedure. The polarization orientation in a nanoisland is toggled to the desired variant after a reset operation by scanning a conductive atomic force probe in contact over the surface while a bias is applied. The final polarization variant is determined by the direction of the inhomogeneous in-plane trailing field associated with the moving probe tip. This work provides the framework for better control of switching in rhombohedral ferroelectrics and for a deeper understanding of exchange coupling in multiferroic nanoscale heterostructures toward the realization of magnetoelectric devices. PMID:27454612

  10. Dirac fermions at high-index surfaces of bismuth chalcogenide topological insulator nanostructures

    NASA Astrophysics Data System (ADS)

    Virk, Naunidh; Yazyev, Oleg V.

    2016-02-01

    Binary bismuth chalcogenides Bi2Se3, Bi2Te3, and related materials are currently being extensively investigated as the reference topological insulators (TIs) due to their simple surface-state band dispersion (single Dirac cone) and relatively large bulk band gaps. Nanostructures of TIs are of particular interest as an increased surface-to-volume ratio enhances the contribution of surfaces states, meaning they are promising candidates for potential device applications. So far, the vast majority of research efforts have focused on the low-energy (0001) surfaces, which correspond to natural cleavage planes in these layered materials. However, the surfaces of low-dimensional nanostructures (nanoplatelets, nanowires, nanoribbons) inevitably involve higher-index facets. We perform a systematic ab initio investigation of the surfaces of bismuth chalcogenide TI nanostructures characterized by different crystallographic orientations, atomic structures and stoichiometric compositions. We find several stable terminations of high-index surfaces, which can be realized at different values of the chemical potential of one of the constituent elements. For the uniquely defined stoichiometric termination, the topological Dirac fermion states are shown to be strongly anisotropic with a clear dependence of Fermi velocities and spin polarization on the surface orientation. Self-doping effects and the presence of topologically trivial mid-gap states are found to characterize the non-stoichiometric surfaces. The results of our study pave the way towards experimental control of topologically protected surface states in bismuth chalcogenide nanostructures.

  11. Dirac fermions at high-index surfaces of bismuth chalcogenide topological insulator nanostructures

    PubMed Central

    Virk, Naunidh; Yazyev, Oleg V.

    2016-01-01

    Binary bismuth chalcogenides Bi2Se3, Bi2Te3, and related materials are currently being extensively investigated as the reference topological insulators (TIs) due to their simple surface-state band dispersion (single Dirac cone) and relatively large bulk band gaps. Nanostructures of TIs are of particular interest as an increased surface-to-volume ratio enhances the contribution of surfaces states, meaning they are promising candidates for potential device applications. So far, the vast majority of research efforts have focused on the low-energy (0001) surfaces, which correspond to natural cleavage planes in these layered materials. However, the surfaces of low-dimensional nanostructures (nanoplatelets, nanowires, nanoribbons) inevitably involve higher-index facets. We perform a systematic ab initio investigation of the surfaces of bismuth chalcogenide TI nanostructures characterized by different crystallographic orientations, atomic structures and stoichiometric compositions. We find several stable terminations of high-index surfaces, which can be realized at different values of the chemical potential of one of the constituent elements. For the uniquely defined stoichiometric termination, the topological Dirac fermion states are shown to be strongly anisotropic with a clear dependence of Fermi velocities and spin polarization on the surface orientation. Self-doping effects and the presence of topologically trivial mid-gap states are found to characterize the non-stoichiometric surfaces. The results of our study pave the way towards experimental control of topologically protected surface states in bismuth chalcogenide nanostructures. PMID:26847409

  12. Dirac fermions at high-index surfaces of bismuth chalcogenide topological insulator nanostructures.

    PubMed

    Virk, Naunidh; Yazyev, Oleg V

    2016-01-01

    Binary bismuth chalcogenides Bi2Se3, Bi2Te3, and related materials are currently being extensively investigated as the reference topological insulators (TIs) due to their simple surface-state band dispersion (single Dirac cone) and relatively large bulk band gaps. Nanostructures of TIs are of particular interest as an increased surface-to-volume ratio enhances the contribution of surfaces states, meaning they are promising candidates for potential device applications. So far, the vast majority of research efforts have focused on the low-energy (0001) surfaces, which correspond to natural cleavage planes in these layered materials. However, the surfaces of low-dimensional nanostructures (nanoplatelets, nanowires, nanoribbons) inevitably involve higher-index facets. We perform a systematic ab initio investigation of the surfaces of bismuth chalcogenide TI nanostructures characterized by different crystallographic orientations, atomic structures and stoichiometric compositions. We find several stable terminations of high-index surfaces, which can be realized at different values of the chemical potential of one of the constituent elements. For the uniquely defined stoichiometric termination, the topological Dirac fermion states are shown to be strongly anisotropic with a clear dependence of Fermi velocities and spin polarization on the surface orientation. Self-doping effects and the presence of topologically trivial mid-gap states are found to characterize the non-stoichiometric surfaces. The results of our study pave the way towards experimental control of topologically protected surface states in bismuth chalcogenide nanostructures. PMID:26847409

  13. Use of a Soluble Anode in Electrodeposition of Thick Bismuth Telluride Layers

    NASA Astrophysics Data System (ADS)

    Maas, M.; Diliberto, S.; de Vaulx, C.; Azzouz, K.; Boulanger, C.

    2014-10-01

    Integration of thermoelectric devices within an automotive heat exchanger could enable conversion of lost heat into electrical energy, contributing to improved total output from the engine. For this purpose, synthesis of thick bismuth telluride (Bi2Te3) films is required. Bismuth telluride has been produced by an electrochemical method in nitric acid with a sacrificial bismuth telluride anode as the source of cations. The binary layer grows on the working electrode while the counter-electrode, a Bi2Te3 disk obtained by high frequency melting, is oxidized to BiIII and TeIV. This process leads to auto-regeneration of the solution without modification of its composition. The thickness of films deposited by use of the Bi2Te3 anode was approximately 10 times that without. To demonstrate the utility of a soluble anode in electrochemical deposition, we report characterization of the composition and morphology of the films obtained under different experimental conditions. Perfectly dense and regular Bi2Te3 films (˜400 μm) with low internal stress and uniform composition across the cross-section were prepared. Their thermoelectric properties were assessed.

  14. Electron Paramagnetic Resonance Study of Thermally Treated Bismuth Subgallate

    PubMed Central

    Ramos, Paweł; Pilawa, Barbara

    2014-01-01

    Complex of bismuth, an anti-inflammatory drug, was studied by EPR spectroscopy. The aim of this study was to determine concentrations and properties of free radicals formed during thermal sterilization of bismuth subgallate according to pharmacopoeia norms to optimize its sterilization process. Different temperatures (160°C, 170°C, and 180°C) and times (120 minutes, 60 minutes, and 30 minutes) of sterilization were used. Interactions of bismuth subgallate with DPPH, the model free radical reference, were checked. g-Factors, amplitudes (A), integral intensities (I), and linewidths (ΔBpp) were obtained. Integral intensities were obtained by double integration of the first-derivative EPR lines. The influence of microwave power in the range of 2.2–70 mW on shape and parameters of the EPR spectra was examined. Thermal sterilization produced free radicals in bismuth subgallate in all tested cases. Strong interactions with free radicals were pointed out for all the analysed samples containing bismuth independent of sterilization conditions. Optimal conditions of thermal sterilization for bismuth subgallate with the lowest free radical formation are temperature 170°C and time of heating 60 minutes. Strong dipolar interactions exist in thermally sterilized bismuth subgallate. EPR spectroscopy is a useful method of examination of thermal sterilization conditions. PMID:25525421

  15. Electron paramagnetic resonance study of thermally treated bismuth subgallate.

    PubMed

    Ramos, Paweł; Pilawa, Barbara

    2014-01-01

    Complex of bismuth, an anti-inflammatory drug, was studied by EPR spectroscopy. The aim of this study was to determine concentrations and properties of free radicals formed during thermal sterilization of bismuth subgallate according to pharmacopoeia norms to optimize its sterilization process. Different temperatures (160°C, 170°C, and 180°C) and times (120 minutes, 60 minutes, and 30 minutes) of sterilization were used. Interactions of bismuth subgallate with DPPH, the model free radical reference, were checked. g-Factors, amplitudes (A), integral intensities (I), and linewidths (ΔB pp) were obtained. Integral intensities were obtained by double integration of the first-derivative EPR lines. The influence of microwave power in the range of 2.2-70 mW on shape and parameters of the EPR spectra was examined. Thermal sterilization produced free radicals in bismuth subgallate in all tested cases. Strong interactions with free radicals were pointed out for all the analysed samples containing bismuth independent of sterilization conditions. Optimal conditions of thermal sterilization for bismuth subgallate with the lowest free radical formation are temperature 170°C and time of heating 60 minutes. Strong dipolar interactions exist in thermally sterilized bismuth subgallate. EPR spectroscopy is a useful method of examination of thermal sterilization conditions. PMID:25525421

  16. Development of a direct evaporation bismuth Hall thruster

    NASA Astrophysics Data System (ADS)

    Massey, Dean Richard

    Hall thrusters have been under active development around the world since the 1960's. Thrusters using traditional propellants such as xenon have been flown on a variety of satellite orbit raising and maintenance missions with an excellent record. To expand the mission envelope, it is necessary to lower the specific impulse of the thrusters but xenon and krypton are poor performers at specific impulses below 1,200 seconds. To enhance low specific impulse performance, this dissertation examines the development of a Hall-effect thruster which uses bismuth as a propellant. Bismuth, the heaviest non-radioactive element, holds many advantages over noble gas propellants from an energetics as well as a practical economic standpoint. Low ionization energy, large electron-impact cross-section and high atomic mass make bismuth ideal for low-specific impulse applications. The primary disadvantage lies in the high temperatures which are required to generate the bismuth vapors. Previous efforts carried out in the Soviet Union relied upon the complete bismuth vaporization and gas phase delivery to the anode. While this proved successful, the power required to vaporize and maintain gas phase throughout the mass flow system quickly removed many of the efficiency gains expected from using bismuth. To solve these problems, a unique method of delivering liquid bismuth to the anode has been developed. Bismuth is contained within a hollow anode reservoir that is capped by a porous metallic disc. By utilizing the inherent waste heat generated in a Hall thruster, liquid bismuth is evaporated and the vapors pass through the porous disc into the discharge chamber. Due to the high temperatures and material compatibility requirements, the anode was fabricated out of pure molybdenum. The porous vaporizer was not available commercially so a method of creating a refractory porous plate with 40-50% open porosity was developed. Molybdenum also does not respond well to most forms of welding so a

  17. Luminescent properties of bismuth centres in aluminosilicate optical fibres

    SciTech Connect

    Bulatov, Lenar I; Mashinskii, Valerii M; Dvoirin, Vladislav V; Dianov, Evgenii M; Kustov, Evgenii F

    2010-02-28

    The shape and spectral position of the luminescence bands of bismuth-doped aluminosilicate glass fibres are shown to depend on excitation power and wavelength. This indicates that the red and IR luminescence bands are composed of several components. The absorption and radiative transitions involved are identified, and a diagram of energy levels and transitions is obtained for four modifications of a bismuth centre in different environments in the aluminosilicate glass network. The effect of local environment on the optical properties of the bismuth centres is examined. (optical fibres and waveguides)

  18. Automatic Searching Radioactive Sources by Airborne Radioactive Survey Using Multicopter

    NASA Astrophysics Data System (ADS)

    Rim, H.; Eun, S. B.; Kim, K.; Park, S.; Jung, H. K.

    2015-12-01

    In order to prepare emergency situation lost a dangerous radioelement source in advance and to search a radioactive source automatically, we develop airborne radioelement survey system by multicopter. This multicopter radioelement survey system consists of a small portable customized BGO (Bismuth Germanate Oxide) detector, video recording part, wireless connecting part to ground pilot, GPS, and several equipments for automatic flight. This system is possible to search flight by preprogramed lines. This radioactive detecting system are tested to find intentional hidden source, The performance of detecting a source is well proved with very low flight altitude in spite of depending on the magnitude of radioelement sources. The advantage of multicopter system, one of UAV (Unmanned Aerial Vehicle), is to avoid the potential of close access to a dangerous radioactive source by using fully automatic searching capability. In this paper, we introduce our multicopter system for detecting radioactive source and synthetic case history for demonstrating this system.

  19. A resonance-free nano-film airborne ultrasound emitter

    NASA Astrophysics Data System (ADS)

    Daschewski, Maxim; Harrer, Andrea; Prager, Jens; Kreutzbruck, Marc; Beck, Uwe; Lange, Thorid; Weise, Matthias

    2013-01-01

    In this contribution we present a novel thermo-acoustic approach for the generation of broad band airborne ultrasound and investigate the applicability of resonance-free thermo-acoustic emitters for very short high pressure airborne ultrasound pulses. We report on measurements of thermo-acoustic emitter consisting of a 30 nm thin metallic film on a usual soda-lime glass substrate, generating sound pressure values of more than 140 dB at 60 mm distance from the transducer and compare the results with conventional piezoelectric airborne ultrasound transducers. Our experimental investigations show that such thermo-acoustic devices can be used as broad band emitters using pulse excitation.

  20. The Airborne Laser

    NASA Astrophysics Data System (ADS)

    Lamberson, Steven E.

    2002-09-01

    The US Air Force Airborne Laser (ABL) is an airborne, megawatt-class laser system with a state-of-the-art atmospheric compensation system to destroy enemy ballistic missiles at long ranges. This system will provide both deterrence and defense against the use of such weapons during conflicts. This paper provides an overview of the ABL weapon system including: the notional operational concept, the development approach and schedule, the overall aircraft configuration, the technologies being incorporated in the ABL, and the risk reduction approach being utilized to ensure program success.

  1. Airborne oceanographic lidar system

    NASA Technical Reports Server (NTRS)

    1975-01-01

    Specifications and preliminary design of an Airborne Oceanographic Lidar (AOL) system, which is to be constructed for installation and used on a NASA Wallops Flight Center (WFC) C-54 research aircraft, are reported. The AOL system is to provide an airborne facility for use by various government agencies to demonstrate the utility and practicality of hardware of this type in the wide area collection of oceanographic data on an operational basis. System measurement and performance requirements are presented, followed by a description of the conceptual system approach and the considerations attendant to its development. System performance calculations are addressed, and the system specifications and preliminary design are presented and discussed.

  2. NASA Airborne Lidar July 1991

    Atmospheric Science Data Center

    2016-05-26

    NASA Airborne Lidar July 1991 Data from the 1991 NASA Langley Airborne Lidar flights following the eruption of Pinatubo in July ... and Osborn [1992a, 1992b]. Project Title:  NASA Airborne Lidar Discipline:  Field Campaigns ...

  3. NASA Airborne Lidar May 1992

    Atmospheric Science Data Center

    2016-05-26

    NASA Airborne Lidar May 1992 An airborne Nd:YAG (532 nm) lidar was operated by the NASA Langley Research Center about a year following the June 1991 eruption of ... Osborn [1992a, 1992b].  Project Title:  NASA Airborne Lidar Discipline:  Field Campaigns ...

  4. Bismuth breast and thyroid shield implementation for pediatric CT.

    PubMed

    Dobbs, Melinda; Ahmed, Renee; Patrick, L Ellen

    2011-01-01

    Studies have indicated that infants and children are as much as ten times more susceptible to carcinogenesis from radiation than adults. Because data show bismuth breast and thyroid shields decrease radiation dose to sensitive areas without changes in image quality, Children's Healthcare of Atlanta implemented the use of bismuth shields in all patients undergoing CTexaminations. Staff education regarding the use of bismuth shielding was key to the success of this program.Their understanding of the benefits would ultimately assist in their support of shield use in the CT department. This program was made possible through a grant from the AHRA & Toshiba Putting Patients First Program. Otherwise, the cost of bismuth shielding would be supported by the operating budget of the organization and, with the decline in CT volume reported at many healthcare institutions,this cost may be too high for many hospitals. PMID:21366141

  5. Dielectric investigations of polycrystalline samarium bismuth ferrite ceramic

    SciTech Connect

    Palaimiene, E.; Macutkevic, J.; Banys, J.; Karpinsky, D. V.; Kholkin, A. L.

    2015-01-05

    Results of broadband dielectric investigations of samarium doped bismuth ferrite ceramics are presented in wide temperature range (20–800 K). At temperatures higher than 400 K, the dielectric properties of samarium bismuth ferrite ceramics are governed by Maxwell-Wagner relaxation and electrical conductivity. The DC conductivity increases and activation energy decreases with samarium concentration. In samarium doped bismuth ferrite, the ferroelectric phase transition temperature decreases with samarium concentration and finally no ferroelectric order is observed at x = 0.2. At lower temperatures, the dielectric properties of ferroelectric samarium doped bismuth ferrite are governed by ferroelectric domains dynamics. Ceramics with x = 0.2 exhibit the relaxor-like behaviour.

  6. Optical Properties of Bismuth Germanate (BGO)

    SciTech Connect

    Jellison Jr, Gerald Earle; Auluck, S.; Singh, David J; Boatner, Lynn A

    2010-01-01

    The optical dielectric function of bismuth germanate Bi4Ge3O12 has been measured using spectroscopic ellipsometry and optical transmission. Analysis near the direct band edge indicates that there are at least three critical points at 4.44 low intensity and at 4.75 and 4.91 high intensity. Using transmission measurements, the band gap is determined to be 4.20 eV, which is likely determined by the defects in the material. Comparisons are made with relativistic electronic structure and optical calculations based on the Engel Vosko generalized gradient approximation. The near-absorption-edge critical points are associated with spin-orbit-split bands which significantly modify the conduction bands.

  7. OPTICAL FIBRES AND FIBREOPTIC SENSORS: Bismuth-ring-doped fibres

    NASA Astrophysics Data System (ADS)

    Zlenko, Aleksandr S.; Akhmetshin, Ural G.; Dvoirin, Vladislav V.; Bogatyrev, Vladimir A.; Firstov, Sergei V.

    2009-11-01

    A new process for bismuth doping of optical fibres is proposed in which the dopant is introduced into a thin layer surrounding the fibre core. This enables bismuth stabilisation in the silica glass, with no limitations on the core composition. In particular, the GeO2 content of the fibre core in this study is 16 mol %. Spectroscopic characterisation of such fibres and optical gain measurements suggest that the proposed approach has considerable potential for laser applications.

  8. Effect of Octamethylcyclotetrasiloxane on Methylation of Bismuth by Methanosarcina barkeri

    PubMed Central

    Michalke, Klaus; Meyer, Jörg; Hensel, Reinhard

    2006-01-01

    Octamethylcyclotetrasiloxane (OMCTS), a common constituent of household products, triggers the transformation of bismuth to the volatile toxic derivative trimethylbismuth by Methanosarcina barkeri, which is a representative member of the sewage sludge microflora. Comparative studies with the ionophores monensin and lasalocid, which induce effects similar to those observed for OMCTS, indicated that the stimulation of bismuth methylation is not specific for the siloxane and suggested that the stimulation observed is mainly due to facilitated membrane permeation of the metal ion. PMID:17021235

  9. Bismuth alloying properties in GaAs nanowires

    SciTech Connect

    Ding, Lu; Lu, Pengfei; Cao, Huawei; Cai, Ningning; Yu, Zhongyuan; Gao, Tao; Wang, Shumin

    2013-09-15

    First-principles calculations have been performed to investigate the structural, electronic and optical properties of bismuth alloying in GaAs nanowires. A typical model of Ga{sub 31}As{sub 31} nanowires is introduced for its reasonable band gap. The band gap of GaAs{sub 1−x}Bi{sub x} shrinks clearly with the increasing Bi concentration and the band edge shifts when spin–orbit coupling (SOC) is considered. The insertion of Bi atom leads to hybridization of Ga/As/Bi p states which contributes a lot around Fermi level. Scissor effect is involved. The optical properties are presented, including dielectric function, optical absorption spectra and reflectivity, which are also varied with the increasing of Bi concentrations. - Graphical abstract: Top view of Bi-doped GaAs nanowires. Ga, As, and Bi atoms are denoted with grey, purple and red balls, respectively. Display Omitted - Highlights: • A typical model of Ga{sub 31}As{sub 31} nanowires is introduced for its reasonable band gap. • The band gap of GaAs{sub 1−x}Bi{sub x} shrinks clearly with the increasing Bi concentration. • The band edge shifts when spin–orbit coupling (SOC) is considered. • The insertion of Bi atom leads to hybridization of Ga/As/Bi p states.

  10. Airborne antenna pattern calculations

    NASA Technical Reports Server (NTRS)

    Knerr, T. J.; Schaffner, P. R.; Mielke, R. R.; Gilreath, M. C.

    1980-01-01

    A procedure for numerically calculating radiation patterns of fuselage-mounted airborne antennas using the Volumetric Pattern Analysis Program is presented. Special attention is given to aircraft modeling. An actual case study involving a large commercial aircraft is included to illustrate the analysis procedure.

  11. Recognizing Airborne Hazards.

    ERIC Educational Resources Information Center

    Schneider, Christian M.

    1990-01-01

    The heating, ventilating, and air conditioning (HVAC) systems in older buildings often do not adequately handle air-borne contaminants. Outlines a three-stage Indoor Air Quality (IAQ) assessment and describes a case in point at a Pittsburgh, Pennsylvania, school. (MLF)

  12. Airborne Fraunhofer Line Discriminator

    NASA Technical Reports Server (NTRS)

    Gabriel, F. C.; Markle, D. A.

    1969-01-01

    Airborne Fraunhofer Line Discriminator enables prospecting for fluorescent materials, hydrography with fluorescent dyes, and plant studies based on fluorescence of chlorophyll. Optical unit design is the coincidence of Fraunhofer lines in the solar spectrum occurring at the characteristic wavelengths of some fluorescent materials.

  13. Airborne Remote Sensing

    NASA Technical Reports Server (NTRS)

    1992-01-01

    NASA imaging technology has provided the basis for a commercial agricultural reconnaissance service. AG-RECON furnishes information from airborne sensors, aerial photographs and satellite and ground databases to farmers, foresters, geologists, etc. This service produces color "maps" of Earth conditions, which enable clients to detect crop color changes or temperature changes that may indicate fire damage or pest stress problems.

  14. Investigation Of Dispersive Conductivity And Dielectric Losses In Barium Bismuth Silicate Glasses

    NASA Astrophysics Data System (ADS)

    Ahlawat, Neetu; Sanghi, Sujata; Agarwal, Ashish; Ahlawat, Navneet; Aghamkar, Praveen; Monica

    2011-12-01

    Barium bismuth silicate glasses (BBS glasses) with composition were prepared by normal melt quench technique. The dispersive conductivity and dielectric losses in these glasses were investigated by impedance spectroscopy. The analyses of ac conductivity spectra show a crossover from ion hopping conductivity to nearly constant loss (NCL) contribution in all the glasses. The variations in dielectric constant ɛ*(ω) = ɛ'(ω)-íɛ″(ω) with frequency and temperature indicate an increase in electrode polarization, which reduces the dipolar relaxation effects in these glasses. The increased concentration of BaO in the glass composition reduces the dielectric losses in the present glasses.

  15. International Symposium on Airborne Geophysics

    NASA Astrophysics Data System (ADS)

    Mogi, Toru; Ito, Hisatoshi; Kaieda, Hideshi; Kusunoki, Kenichiro; Saltus, Richard W.; Fitterman, David V.; Okuma, Shigeo; Nakatsuka, Tadashi

    2006-05-01

    Airborne geophysics can be defined as the measurement of Earth properties from sensors in the sky. The airborne measurement platform is usually a traditional fixed-wing airplane or helicopter, but could also include lighter-than-air craft, unmanned drones, or other specialty craft. The earliest history of airborne geophysics includes kite and hot-air balloon experiments. However, modern airborne geophysics dates from the mid-1940s when military submarine-hunting magnetometers were first used to map variations in the Earth's magnetic field. The current gamut of airborne geophysical techniques spans a broad range, including potential fields (both gravity and magnetics), electromagnetics (EM), radiometrics, spectral imaging, and thermal imaging.

  16. Synthesis and Characterization of High-Purity Bismuth Nanowires via Seed-Assisted Growth Approach

    NASA Astrophysics Data System (ADS)

    Mu, Xin; Zhao, Wen-Yu; He, Dan-Qi; Zhou, Hong-Yu; Zhu, Wan-Ting; Zhang, Qing-Jie

    2015-06-01

    Nanowires are considered as high-performance thermoelectric materials with large Seebeck coefficients due to quantum confinement and low thermal conductivity because of enhanced boundary scattering of phonons. In this work, a seed-assisted growth method has been developed to synthesize high-purity bismuth nanowires. The bismuth seeds were first synthesized by reducing BiCl3 in the ice water with NaBH4. The high-purity bismuth nanowires about 40-50 nm in diameter and several tens of micrometers in length were then grown on bismuth seeds by reducing NaBiO3 with ethylene glycol. X-ray diffraction, scanning electron microscopy, and transmission electron microscopy were employed to characterize the crystal structure, microstructure, and growth direction of the bismuth seeds and nanowires. The effects of temperature, reductant, and bismuth seeds template on the microstructures of the bismuth nanowires were also investigated. The synthesis conditions of bismuth seeds and nanowires were optimized. The selected area electron diffraction pattern confirms that the growth direction of bismuth nanowires is parallel to [] direction. It was discovered that high-purity bismuth nanowires with high aspect ratio can be synthesized by precisely controlling the temperature to adjust the nucleation rate of the bismuth nuclei, selecting the appropriate reductant to maintain a low nucleation rate, and using bismuth seeds as the template of the epitaxial growth of the bismuth nuclei.

  17. [Air-borne disease].

    PubMed

    Lameiro Vilariño, Carmen; del Campo Pérez, Victor M; Alonso Bürger, Susana; Felpeto Nodar, Irene; Guimarey Pérez, Rosa; Pérez Alvarellos, Alberto

    2003-11-01

    Respiratory protection is a factor which worries nursing professionals who take care of patients susceptible of transmitting microorganisms through the air more as every day passes. This type of protection covers the use of surgical or hygienic masks against the transmission of infection by airborne drops to the use of highly effective masks or respirators against the transmission of airborne diseases such as tuberculosis or SARS, a recently discovered disease. The adequate choice of this protective device and its correct use are fundamental in order to have an effective protection for exposed personnel. The authors summarize the main protective respiratory devices used by health workers, their characteristics and degree of effectiveness, as well as the circumstances under which each device is indicated for use. PMID:14705591

  18. Airborne forest fire research

    NASA Technical Reports Server (NTRS)

    Mattingly, G. S.

    1974-01-01

    The research relating to airborne fire fighting systems is reviewed to provide NASA/Langley Research Center with current information on the use of aircraft in forest fire operations, and to identify research requirements for future operations. A literature survey, interview of forest fire service personnel, analysis and synthesis of data from research reports and independent conclusions, and recommendations for future NASA-LRC programs are included.

  19. MLS airborne antenna research

    NASA Technical Reports Server (NTRS)

    Yu, C. L.; Burnside, W. D.

    1975-01-01

    The geometrical theory of diffraction was used to analyze the elevation plane pattern of on-aircraft antennas. The radiation patterns for basic elements (infinitesimal dipole, circumferential and axial slot) mounted on fuselage of various aircrafts with or without radome included were calculated and compared well with experimental results. Error phase plots were also presented. The effects of radiation patterns and error phase plots on the polarization selection for the MLS airborne antenna are discussed.

  20. Airborne field strength monitoring

    NASA Astrophysics Data System (ADS)

    Bredemeyer, J.; Kleine-Ostmann, T.; Schrader, T.; Münter, K.; Ritter, J.

    2007-06-01

    In civil and military aviation, ground based navigation aids (NAVAIDS) are still crucial for flight guidance even though the acceptance of satellite based systems (GNSS) increases. Part of the calibration process for NAVAIDS (ILS, DME, VOR) is to perform a flight inspection according to specified methods as stated in a document (DOC8071, 2000) by the International Civil Aviation Organization (ICAO). One major task is to determine the coverage, or, in other words, the true signal-in-space field strength of a ground transmitter. This has always been a challenge to flight inspection up to now, since, especially in the L-band (DME, 1GHz), the antenna installed performance was known with an uncertainty of 10 dB or even more. In order to meet ICAO's required accuracy of ±3 dB it is necessary to have a precise 3-D antenna factor of the receiving antenna operating on the airborne platform including all losses and impedance mismatching. Introducing precise, effective antenna factors to flight inspection to achieve the required accuracy is new and not published in relevant papers yet. The authors try to establish a new balanced procedure between simulation and validation by airborne and ground measurements. This involves the interpretation of measured scattering parameters gained both on the ground and airborne in comparison with numerical results obtained by the multilevel fast multipole algorithm (MLFMA) accelerated method of moments (MoM) using a complex geometric model of the aircraft. First results will be presented in this paper.

  1. Mutagenicity of airborne particles.

    PubMed

    Chrisp, C E; Fisher, G L

    1980-09-01

    The physical and chemical properties of airborne particles are important for the interpretation of their potential biologic significance as genotoxic hazards. For polydisperse particle size distributions, the smallest, most respirable particles are generally the most mutagenic. Particulate collection for testing purposes should be designed to reduce artifact formation and allow condensation of mutagenic compounds. Other critical factors such as UV irradiation, wind direction, chemical reactivity, humidity, sample storage, and temperature of combustion are important. Application of chemical extraction methods and subsequent class fractionation techniques influence the observed mutagenic activity. Particles from urban air, coal fly ash, automobile and diesel exhaust, agricultural burning and welding fumes contain primarily direct-acting mutagens. Cigarette smoke condensate, smoke from charred meat and protein pyrolysates, kerosene soot and cigarette smoke condensates contain primarily mutagens which require metabolic activation. Fractionation coupled with mutagenicity testing indicates that the most potent mutagens are found in the acidic fractions of urban air, coal fly ash, and automobile diesel exhaust, whereas mutagens in rice straw smoke and cigarette smoke condensate are found primarily in the basic fractions. The interaction of the many chemical compounds in complex mixtures from airborne particles is likely to be important in determining mutagenic or comutagenic potentials. Because the mode of exposure is generally frequent and prolonged, the presence of tumor-promoting agents in complex mixtures may be a major factor in evaluation of the carcinogenic potential of airborne particles. PMID:7005667

  2. Airborne wireless communication systems, airborne communication methods, and communication methods

    DOEpatents

    Deaton, Juan D.; Schmitt, Michael J.; Jones, Warren F.

    2011-12-13

    An airborne wireless communication system includes circuitry configured to access information describing a configuration of a terrestrial wireless communication base station that has become disabled. The terrestrial base station is configured to implement wireless communication between wireless devices located within a geographical area and a network when the terrestrial base station is not disabled. The circuitry is further configured, based on the information, to configure the airborne station to have the configuration of the terrestrial base station. An airborne communication method includes answering a 911 call from a terrestrial cellular wireless phone using an airborne wireless communication system.

  3. Homogeneity of bismuth-distribution in bismuth-doped alkali germanate laser glasses towards superbroad fiber amplifiers.

    PubMed

    Zhao, Yanqi; Wondraczek, Lothar; Mermet, Alain; Peng, Mingying; Zhang, Qinyuan; Qiu, Jianrong

    2015-05-01

    Compared to rare-earth doped glasses, bismuth-doped glasses hold promise for super-broadband near-infrared (NIR) photoemission and potential applications in optical amplification. However, optically active bismuth centers are extremely sensitive to the properties of the surrounding matrix, and also to processing conditions. This is strongly complicating the exploitation of this class of materials, because functional devices require a very delicate adjustment of the redox state of the bismuth species, and its distribution throughout the bulk of the material. It also largely limits some of the conventional processing routes for glass fiber, which start from gas phase deposition and may require very high processing temperature. Here, we investigate the influence of melting time and alkali addition on bismuth-related NIR photoluminescence from melt-derived germanate glasses. We show that the effect of melting time on bismuth-related absorption and NIR photoemission is primarily through bismuth volatilization. Adding alkali oxides as fluxing agents, the melt viscosity can be lowered to reduce either the glass melting temperature, or the melting time, or both. At the same time, however, alkali addition also leads to increasing mean-field basicity, what may reduce the intensity of bismuth-related NIR emission. Preferentially using Li2O over Na2O or K2O presents the best trade-off between those above factors, because its local effect may be adverse to the generally assumed trend of the negative influence of more basic matrix composition. This observation provides an important guideline for the design of melt-derived Bi-doped glasses with efficient NIR photoemission and high optical homogeneity. PMID:25969328

  4. Full spin polarization of complex ferrimagnetic bismuth iron garnet probed by magneto-optical Faraday spectroscopy

    NASA Astrophysics Data System (ADS)

    Deb, Marwan; Popova, Elena; Fouchet, Arnaud; Keller, Niels

    2013-06-01

    We investigate the spin-dependent electronic density of states near and above the Fermi level in bismuth iron garnet (BIG), Bi3Fe5O12, by magnetic circular dichroism and magneto-optical Faraday spectroscopy. BIG is a recently synthesized material, as its preparation requires special nonequilibrium conditions. Its scientific and applicative interest resides in huge specific Faraday rotation of the incident light, useful for magneto-optic applications. We show experimentally the presence of spin gaps in the conduction band as recently predicted theoretically by Oikawa [T. Oikawa, S. Suzuki, and K. Nakao, J. Phys. Soc. Jpn.JUPSAU0031-901510.1143/JPSJ.74.401 74, 401 (2005)]. In the range of photon energies, where full spin polarization is expected, completely asymmetric Faraday hysteresis loops were observed, similar to those observed in half-metals such as (Pr,La)0.7Ca0.3MnO3 and Fe3O4. These results were modeled using even and odd (with respect to magnetization) contributions into hysteresis loops. The odd contribution appears only in the energy ranges where the density of states is fully spin polarized and vanishes at the Curie temperature. These results open a new perspective for the use of bismuth iron garnet in optic spintronics at room temperature and above.

  5. Magnetic field resistant quantum interferences in Josephson junctions based on bismuth nanowires

    NASA Astrophysics Data System (ADS)

    Li, Chuan; Kasumov, A.; Murani, Anil; Sengupta, Shamashis; Fortuna, F.; Napolskii, K.; Koshkodaev, D.; Tsirlina, G.; Kasumov, Y.; Khodos, I.; Deblock, R.; Ferrier, M.; Guéron, S.; Bouchiat, H.

    2014-12-01

    We investigate proximity-induced superconductivity in micrometer-long bismuth nanowires connected to superconducting electrodes with a high critical field. At low temperature we measure a supercurrent that persists in magnetic fields as high as the critical field of the electrodes (above 11 T). The critical current is also strongly modulated by the magnetic field. In certain samples we find regular, rapid SQUID-like periodic oscillations occurring up to high fields. Other samples exhibit less periodic but full modulations of the critical current on Tesla field scales, with field-caused extinctions of the supercurrent. These findings indicate the existence of low dimensionality, phase coherent, interfering conducting regions through the samples, with a subtle interplay between orbital and spin contributions. We relate these surprising results to the electronic properties of the surface states of bismuth, strong Rashba spin-orbit coupling, large effective g factors, and their effect on the induced pair correlations. In particular, we emphasize the possible contribution of topological edge states of specific facets of the nanowires.

  6. Airborne Submillimeter Spectroscopy

    NASA Technical Reports Server (NTRS)

    Zmuidzinas, J.

    1998-01-01

    This is the final technical report for NASA-Ames grant NAG2-1068 to Caltech, entitled "Airborne Submillimeter Spectroscopy", which extended over the period May 1, 1996 through January 31, 1998. The grant was funded by the NASA airborne astronomy program, during a period of time after the Kuiper Airborne Observatory was no longer operational. Instead. this funding program was intended to help develop instrument concepts and technology for the upcoming SOFIA (Stratospheric Observatory for Infrared Astronomy) project. SOFIA, which is funded by NASA and is now being carried out by a consortium lead by USRA (Universities Space Research Association), will be a 747 aircraft carrying a 2.5 meter diameter telescope. The purpose of our grant was to fund the ongoing development of sensitive heterodyne receivers for the submillimeter band (500-1200 GHz), using sensitive superconducting (SIS) detectors. In 1997 July we submitted a proposal to USRA to construct a heterodyne instrument for SOFIA. Our proposal was successful [1], and we are now continuing our airborne astronomy effort with funding from USRA. A secondary purpose of the NAG2-1068 grant was to continue the anaIN'sis of astronomical data collected with an earlier instrument which was flown on the NASA Kuiper Airborne Observatory (KAO). The KAO instrument and the astronomical studies which were carried out with it were supported primarily under another grant, NAG2-744, which extended over October 1, 1991 through Januarv 31, 1997. For a complete description of the astronomical data and its anailysis, we refer the reader to the final technical report for NAG2-744, which was submitted to NASA on December 1. 1997. Here we report on the SIS detector development effort for SOFIA carried out under NAG2-1068. The main result of this effort has been the demonstration of SIS mixers using a new superconducting material niobium titanium nitride (NbTiN), which promises to deliver dramatic improvements in sensitivity in the 700

  7. Ultrasonication of Bismuth Telluride Nanocrystals Fabricated by Solvothermal Method

    NASA Technical Reports Server (NTRS)

    Chu, Sang-Hyon; Choi, Sang H.; Kim, Jae-Woo; King, Glen C.; Elliott, James R.

    2006-01-01

    The objective of this study is to evaluate the effect of ultrasonication on bismuth telluride nanocrystals prepared by solvothermal method. In this study, a low dimensional nanocrystal of bismuth telluride (Bi2Te3) was synthesized by a solvothermal process in an autoclave at 180 C and 200 psi. During the solvothermal reaction, organic surfactants effectively prevented unwanted aggregation of nanocrystals in a selected solvent while controlling the shape of the nanocrystal. The atomic ratio of bismuth and tellurium was determined by energy dispersive spectroscopy (EDS). The cavitational energy created by the ultrasonic probe was varied by the ultrasonication process time, while power amplitude remained constant. The nanocrystal size and its size distribution were measured by field emission scanning electron microscopy (FESEM) and a dynamic light scattering system. When the ultrasonication time increased, the average size of bismuth telluride nanocrystal gradually increased due to the direct collision of nanocrystals. The polydispersity of the nanocrystals showed a minimum when the ultrasonication was applied for 5 min. Keywords: bismuth telluride, nanocrystal, low-dimensional, ultrasonication, solvothermal

  8. Integrated Liquid Bismuth Propellant Feed System

    NASA Technical Reports Server (NTRS)

    Polzin, Kurt A.; Markusic, Thomas E.; Stanojev, Boris J.

    2006-01-01

    A prototype bismuth propellant feed and control system was constructed and tested. An electromagnetic pump was used in this system to provide fine control of the hydrostatic pressure, and a new type of in-line flow sensor was developed to provide an accurate, real-time measurement of the mass flow rate. High-temperature material compatibility was a driving design requirement for the pump and flow sensor, leading to the selection of macor for the main body of both components. Post-test inspections of both components revealed no cracks or leaking in either. In separate proof-of-concept experiments, the pump produced a linear pressure rise as a function of current that compared favorably with theoretical pump pressure predictions, with a pressure of 10 kPa at 30 A. Flow sensing was successfully demonstrated in a bench-top test using gallium as a substitute liquid metal. A real-time controller was successfully used to control the entire system, simultaneously monitoring all power supplies and performing data acquisition duties.

  9. Ultrasound in lead-bismuth eutectic

    SciTech Connect

    Dierckx, M.; Van Dyck, D.

    2011-07-01

    The Belgian Nuclear Research Centre (SCK.CEN) is in the process of designing MYRRHA, a new multi-purpose irradiation facility to replace the ageing BR2. MYRRHA is a fast spectrum reactor cooled with lead-bismuth eutectic (LBE). As liquid metal is opaque to visual light, ultrasonic measurement techniques are selected to fulfill essential tasks that, according to our assessment, will be demanded by licensing authorities, in particular: fuel assembly identification and localization of a lost fuel assembly. To that end, a considerable research effort at SCK.CEN is devoted to study ultrasonic propagation in LBE. As ultrasonic experiments in LBE are elaborate and expensive to set up, we are particularly interested in to what extent experiments in water can be extrapolated to LBE - one of the main focuses of this article. We describe and present results of a first experiment with this goal which shows that the signal to noise ratio is better in LBE and that we even see small diffuse reflections up to 40 deg. off normal. On the other hand, we do not see internal reflections in stainless steel objects in LBE which we do in water. Therefore, we conclude that experiments in water can be used to validate algorithms for LBE on the condition that they do not rely on internal reflections. We also present solutions to tackle the essential tasks: fuel assembly identification and lost object localization. The requirements for the ultrasonic equipment implementing these solutions are also discussed. (authors)

  10. Local and global superconductivity in bismuth

    NASA Astrophysics Data System (ADS)

    Baring, Luis A.; da Silva, Robson R.; Kopelevich, Yakov

    2011-10-01

    We performed magnetization M(H, T) and magnetoresistance R(T, H) measurements on powdered (grain size ˜149 μm) as well as highly oriented rhombohedral (A7) bismuth (Bi) samples consisting of single crystalline blocks of size ˜1 × 1 mm in the plane perpendicular to the trigonal c axis. The obtained results revealed the occurrence of (1) local superconductivity in powdered samples with Tc(0) = (8.75 ± 0.05) K, and (2) global superconductivity at Tc(0) = (7.3 ± 0.1) K in polycrystalline Bi triggered by low-resistance ohmic contacts with silver (Ag) normal metal. The results provide evidence that the superconductivity in Bi is localized in a tiny volume fraction, probably at intergrain or Ag/Bi interfaces. On the other hand, the occurrence of global superconductivity observed for polycrystalline Bi can be accounted for by enhancement of the superconducting order parameter phase stiffness induced by the normal metal contacts, the scenario proposed in the context of "pseudogap regime" in cuprates [E. Berg et al., Phys. Rev. B 78, 094509 (2008)].

  11. LMO dielectronic resonances in highly charged bismuth

    NASA Astrophysics Data System (ADS)

    Smiga, Joseph; Gillaspy, John; Podpaly, Yuri; Ralchenko, Yuri

    2016-05-01

    Dielectronic resonances from high-Z elements are important for the analysis of high temperature plasmas. Thus, the extreme ultraviolet spectra of highly charged bismuth were measured using the NIST electron beam ion trap (EBIT) at beam energies ranging from 8.7 keV to 9.2 keV. The measured intensity ratios between forbidden magnetic-dipole lines in Bi64+ and Bi63+ show strong resonance features. The experimental data were compared to theoretical predictions from a large-scale collisional-radiative model with the code NOMAD, and good agreement was found that allowed the identification of observed resonance features as the LMO inner-shell dielectronic resonances. It is common practice in EBIT experiments that ions are periodically dumped from the trap and replaced. However, in this particular experiment, the contents of the trap were not dumped for the duration of each 10 minute sampling. The effects of trap stability were studied and a small but noticeable shift in beam energy over time was observed. Potential explanations for this are considered.

  12. 40 CFR 471.10 - Applicability; description of the lead-tin-bismuth forming subcategory.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...-tin-bismuth forming subcategory. 471.10 Section 471.10 Protection of Environment ENVIRONMENTAL... METAL POWDERS POINT SOURCE CATEGORY Lead-Tin-Bismuth Forming Subcategory § 471.10 Applicability; description of the lead-tin-bismuth forming subcategory. This subpart applies to discharges of pollutants...

  13. 40 CFR 471.10 - Applicability; description of the lead-tin-bismuth forming subcategory.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...-tin-bismuth forming subcategory. 471.10 Section 471.10 Protection of Environment ENVIRONMENTAL... METAL POWDERS POINT SOURCE CATEGORY Lead-Tin-Bismuth Forming Subcategory § 471.10 Applicability; description of the lead-tin-bismuth forming subcategory. This subpart applies to discharges of pollutants...

  14. 40 CFR 471.10 - Applicability; description of the lead-tin-bismuth forming subcategory.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...-tin-bismuth forming subcategory. 471.10 Section 471.10 Protection of Environment ENVIRONMENTAL... METAL POWDERS POINT SOURCE CATEGORY Lead-Tin-Bismuth Forming Subcategory § 471.10 Applicability; description of the lead-tin-bismuth forming subcategory. This subpart applies to discharges of pollutants...

  15. Seedless Growth of Bismuth Nanowire Array via Vacuum Thermal Evaporation.

    PubMed

    Liu, Mingzhao; Nam, Chang-Yong; Zhang, Lihua

    2015-01-01

    Here a seedless and template-free technique is demonstrated to scalably grow bismuth nanowires, through thermal evaporation in high vacuum at RT. Conventionally reserved for the fabrication of metal thin films, thermal evaporation deposits bismuth into an array of vertical single crystalline nanowires over a flat thin film of vanadium held at RT, which is freshly deposited by magnetron sputtering or thermal evaporation. By controlling the temperature of the growth substrate the length and width of the nanowires can be tuned over a wide range. Responsible for this novel technique is a previously unknown nanowire growth mechanism that roots in the mild porosity of the vanadium thin film. Infiltrated into the vanadium pores, the bismuth domains (~ 1 nm) carry excessive surface energy that suppresses their melting point and continuously expels them out of the vanadium matrix to form nanowires. This discovery demonstrates the feasibility of scalable vapor phase synthesis of high purity nanomaterials without using any catalysts. PMID:26709727

  16. Mixed-phase bismuth ferrite nanoflake electrodes for supercapacitor application

    NASA Astrophysics Data System (ADS)

    Jadhav, Vijaykumar V.; Zate, Manohar K.; Liu, Shude; Naushad, Mu.; Mane, Rajaram S.; Hui, K. N.; Han, Sung-Hwan

    2016-04-01

    Nanoflake bismuth ferrite thin film was synthesized by means of electrodeposition technique at room temperature. The morphology and phase evaluation of the synthesized electrode were analyzed using scanning electron microscopy, X-ray diffraction, Raman spectroscopy, and surface wettability techniques. Specifically, the bismuth ferrite nanoflake electrode exhibited high specific capacitance of 72.2 F g-1 at a current density of 1 A g-1, and high rate capability with 37 % retention of capacitance even up to 20A g-1, and excellent cycling stability with 82.8 % retention of the initial capacitance after 1500 charge/discharge cycles, supporting that the bismuth ferrite thin-film electrode could be a potential candidate for supercapacitor application.

  17. Characterization of bismuth nanospheres deposited by plasma focus device

    SciTech Connect

    Ahmad, M.; Al-Hawat, Sh.; Akel, M.; Mrad, O.

    2015-02-14

    A new method for producing thin layer of bismuth nanospheres based on the use of low energy plasma focus device is demonstrated. Various techniques such as scanning electron microscopy, Rutherford backscattering spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and Raman spectroscopy have been used to characterize the morphology and the composition of the nanospheres. Experimental parameters may be adjusted to favour the formation of bismuth nanospheres instead of microspheres. Therefore, the formation of large surface of homogeneous layer of bismuth nanospheres with sizes of below 100 nm can be obtained. The natural snowball phenomenon is observed to be reproduced in nanoscale where spheres roll over the small nanospheres and grow up to bigger sizes that can reach micro dimensions. The comet-like structure, a reverse phenomenon to snowball is also observed.

  18. Isotopic generator for bismuth-212 and lead-212 from radium

    DOEpatents

    Atcher, Robert W.; Friedman, Arnold M.; Hines, John

    1987-01-01

    A method and apparatus for providing radionuclides of bismuth-212 and lead-212. Thorium-228 and carrier solution starting material is input to a radiologically contained portion of an isotopic generator system, and radium-224 is separated from thorium-228 which is retained by a strongly basic anion exchange column. The separated radium-224 is transferred to an accessible, strongly acidic cationic exchange column. The cationic column retains the radium-224, and natural radioactive decay generates bismuth-212 and lead-212. The cationic exchange column can also be separated from the contained portion of the system and utilized without the extraordinary safety measures necessary in the contained portion. Furthermore, the cationic exchange column provides over a relatively long time period the short lived lead-212 and bismuth-212 radionuclides which are useful for a variety of medical therapies.

  19. Phase transitions in the Hubbard model for the bismuth nickelate

    NASA Astrophysics Data System (ADS)

    Kojima, Shoya; Nasu, Joji; Koga, Akihisa

    2016-07-01

    We study low temperature properties of the Hubbard model for the bismuth nickelate, where degenerate orbitals in the nickel ions and a single orbital in the bismuth ions are taken into account, combining dynamical mean-field theory with the continuous-time quantum Monte Carlo method. We discuss the effect of the attractive interactions to mimic the valence skipping phenomenon in the bismuth ions. We demonstrate how the charge and magnetically ordered states are stable against thermal fluctuations. It is furthermore clarified that the ferromagnetically ordered and orbital ordered states are stabilized due to the presence of the orbital degeneracy at low temperatures. The crossover between metallic and insulating states is also discussed.

  20. Characterization of bismuth nanospheres deposited by plasma focus device

    NASA Astrophysics Data System (ADS)

    Ahmad, M.; Al-Hawat, Sh.; Akel, M.; Mrad, O.

    2015-02-01

    A new method for producing thin layer of bismuth nanospheres based on the use of low energy plasma focus device is demonstrated. Various techniques such as scanning electron microscopy, Rutherford backscattering spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and Raman spectroscopy have been used to characterize the morphology and the composition of the nanospheres. Experimental parameters may be adjusted to favour the formation of bismuth nanospheres instead of microspheres. Therefore, the formation of large surface of homogeneous layer of bismuth nanospheres with sizes of below 100 nm can be obtained. The natural snowball phenomenon is observed to be reproduced in nanoscale where spheres roll over the small nanospheres and grow up to bigger sizes that can reach micro dimensions. The comet-like structure, a reverse phenomenon to snowball is also observed.

  1. Thermal, structural and electrical studies of bismuth zinc borate glasses

    NASA Astrophysics Data System (ADS)

    Shanmugavelu, B.; Ravi Kanth Kumar, V. V.

    2013-06-01

    Bismuth Zinc Borate glasses with compositions xBi2O3-30ZnO-(70 - x)B2O3 (where x = 30, 35, 40 and 45 mol %) have been prepared by melt quenching method. These glasses were characterized by X-ray diffraction (XRD), Differential Thermal Analysis (DTA), Fourier Transform Infrared Spectrometer (FTIR) and Broad Band Dielectric Spectrometer (BDS). DTA and FTIR analysis reveals that Non-Bridging Oxygens (NBOs) increase with increase of bismuth content in the glass. Electrical data have been analyzed in the framework of impedance and modulus formalisms. The activation energy for dc conductivity decreases with increase of bismuth concentration. The imaginary part of modulus spectra has been fitted to non-exponential Kohlrausch-Williams-Watts (KWW) function and the value of the stretched exponent (β) is found to be almost independent of temperature but slightly dependent on composition.

  2. PHARUS airborne SAR concept

    NASA Astrophysics Data System (ADS)

    Snoeij, Paul; Pouwels, Henk; Koomen, Peter J.; Hoogeboom, Peter

    1995-11-01

    PHARUS (phased array universal SAR) is an airborne SAR concept which is being developed in the Netherlands. The PHARUS system differs from other airborne SARs by the use of a phased array antenna, which provides both for the flexibility in the design as well as for a compact, light-weight instrument that can be carried on small aircraft. The concept allows for the construction of airborne SAR systems on a common generic basis but tailored to specific user needs and can be seen as a preparation for future spaceborne SAR systems using solid state transmitters with electronically steerable phased array antenna. The whole approach is aimed at providing an economic and yet technically sophisticated solution to remote sensing or surveying needs of a specific user. The solid state phased array antenna consists of a collection of radiating patches; the design flexibility for a large part resides in the freedom to choose the number of patches, and thereby the essential radar performance parameters such as resolution and swath width. Another consequence of the use of the phased array antenna is the system's compactness and the possibility to rigidly mount it on a small aircraft. The use of small aircraft of course considerably improves the cost/benefit ratio of the use of airborne SAR. Flight altitude of the system is flexible between about 7,000 and 40,000 feet, giving much operational freedom within the meteo and airspace control limits. In the PHARUS concept the airborne segment is complemented by a ground segment, which consists of a SAR processor, possibly extended by a matching image processing package. (A quick look image is available in real-time on board the aircraft.) The SAR processor is UNIX based and runs on easily available hardware (SUN station). Although the additional image processing software is available, the SAR processing software is nevertheless designed to be able to interface with commercially available image processing software, as well as being able

  3. Compact and Integrated Liquid Bismuth Propellant Feed System

    NASA Technical Reports Server (NTRS)

    Polzin, Kurt A.; Stanojev, Boris; Korman, Valentin; Gross, Jeffrey T.

    2007-01-01

    Operation of Hall thrusters with bismuth propellant has been shown to be a promising path toward high-power, high-performance, long-lifetime electric propulsion for spaceflight missions [1]. There has been considerable effort in the past three years aimed at resuscitating this promising technology and validating earlier experimental results indicating the advantages of a bismuth-fed Hall thruster. A critical element of the present effort is the precise metering of propellant to the thruster, since performance cannot be accurately assessed without an accurate accounting of mass flow rate. Earlier work used a pre./post-test propellant weighing scheme that did not provide any real-time measurement of mass flow rate while the thruster was firing, and makes subsequent performance calculations difficult. The motivation of the present work is to develop a precision liquid bismuth Propellant Management System (PMS) that provides hot, molten bismuth to the thruster while simultaneously monitoring in real-time the propellant mass flow rate. The system is a derivative of our previous propellant feed system [2], but the present system represents a more compact design. In addition, all control electronics are integrated into a single unit and designed to reside on a thrust stand and operate in the relevant vacuum environment where the thruster is operating, significantly increasing the present technology readiness level of liquid metal propellant feed systems. The design of various critical components in a bismuth PMS are described. These include the bismuth reservoir and pressurization system, 'hotspot' flow sensor, power system and integrated control system. Particular emphasis is given to selection of the electronics employed in this system and the methods that were used to isolate the power and control systems from the high-temperature portions of the feed system and thruster. Open loop calibration test results from the 'hotspot' flow sensor are reported, and results of

  4. Airborne Raman lidar

    NASA Astrophysics Data System (ADS)

    Heaps, Wm. S.; Burris, J.

    1996-12-01

    We designed and tested an airborne lidar system using Raman scattering to make simultaneous measurements of methane, water vapor, and temperature in a series of flights on a NASA-operated C-130 aircraft. We present the results for methane detection, which show that the instrument has the requisite sensitivity to atmospheric trace gases. Ultimately these measurements can be used to examine the transport of chemically processed air from within the polar vortex to mid-latitudinal regions and the exchange of stratospheric air between tropical and mid-latitudinal regions.

  5. Airborne Oceanographic Lidar System

    NASA Technical Reports Server (NTRS)

    Bressel, C.; Itzkan, I.; Nunes, J. E.; Hoge, F.

    1977-01-01

    The Airborne Oceanographic Lidar (AOL), a spatially scanning range-gated device installed on board a NASA C-54 aircraft, is described. The AOL system is capable of measuring topographical relief or water depth (bathymetry) with a range resolution of plus or minus 0.3 m in the vertical dimension. The system may also be used to measure fluorescent spectral signatures from 3500 to 8000 A with a resolution of 100 A. Potential applications of the AOL, including sea state measurements, water transparency assessments, oil spill identification, effluent identification and crop cover assessment are also mentioned.

  6. Electrical and optical properties of gadolinium doped bismuth ferrite nanoparticles

    SciTech Connect

    Mukherjee, A. Banerjee, M. Basu, S.; Pal, M.

    2014-04-24

    Multiferroic bismuth ferrite (BFO) and gadolinium (Gd) doped bismuth ferrite had been synthesized by a sol-gel method. Particle size had been estimated by Transmission electron microscopy (TEM) and found to decrease with Gd doping. We studied the temperature and frequency dependence of impedance and electric modulus and calculated the grain and grain boundary resistance and capacitance of the investigated samples. We observed that electrical activation energy increases for all the doped samples. Optical band gap also increases for the doped samples which can be used in photocatalytic application of BFO.

  7. Correlation between thermoluminescence and radiation damage in bismuth germanate

    SciTech Connect

    Melcher, C.L.

    1985-02-01

    Thermoluminescence properties of bismuth germanate and their relationship to radiation damage characteristics have been investigated. Thermoluminescence and radiation damage in bismuth germanate display several similar properties including similar responses as a function of radiation dose, similar saturation levels, and similar decay times. Also a correlation was found between the thermoluminescence sensitivities and radiation damage sensitivities of four different crystals. The traps responsible for the radiation damage and those which store the thermoluminescence signal appear to be either closely related or actually the same traps. Four trapping centers can be seen in the thermoluminescence glow curves. The depth of the dominant trap is 1.1 eV. 10 references.

  8. Design of Material Strength Test in Lead-Bismuth Flow

    SciTech Connect

    Masatoshi Kondo; Minoru Takahashi; Koji Hata

    2002-07-01

    Liquid lead and lead-bismuth have drawn the attention as one of the candidate coolants of the fast breeder reactors (FBRs), and the accelerator driven transmutation systems (ADSs). In order to use the coolant to the systems, the physical and chemical characteristics of the heavy metals are necessary. This plan has been proposed for the strength test of materials in the liquid metal surroundings. The lead-bismuth circulation loop with the strength test has been designed, and the strength test of candidate materials has been planned. (authors)

  9. Lead-bismuth eutectic technology for Hyperion reactor

    NASA Astrophysics Data System (ADS)

    Zhang, J.; Kapernick, R. J.; McClure, P. R.; Trapp, T. J.

    2013-10-01

    A small lead-bismuth eutectic-cooled reactor concept (referred to as the Hyperion reactor concept) is being studied at Los Alamos National Laboratory and Hyperion Power Generation. In this report, a critical assessment of the lead-bismuth eutectic technology for Hyperion reactor is presented based on currently available knowledge. Included are: material compatibility, oxygen control, thermal hydraulics, polonium control. The key advances in the technology and their applications to Hyperion reactor design are analyzed. Also, the near future studies in main areas of the technology are recommended for meeting the design requirements.

  10. Inexpensive laser-induced surface modification in bismuth thin films

    NASA Astrophysics Data System (ADS)

    Contreras, A. Reyes; Hautefeuille, M.; García, A. Esparza; Mejia, O. Olea; López, M. A. Camacho

    2015-05-01

    In this work, we present results on texturing a 500 nm thick bismuth film, deposited by sputtering onto a glass slide using a low-cost homemade, near-infrared pulsed laser platform. A 785 nm laser diode of a CD-DVD pickup head was precisely focused on the sample mounted on a motorized two-axis translation stage to generate localized surface microbumps on the bismuth films. This simple method successfully transferred desired micropatterns on the films in a computer-numerical control fashion. Irradiated zones were characterized by atomic force microscopy and scanning electron microscopy. It was observed that final results are strongly dependent on irradiation parameters.

  11. Bismuth-doped optical fibres: A new breakthrough in near-IR lasing media

    SciTech Connect

    Dianov, Evgenii M

    2012-09-30

    Recent results demonstrate that bismuth-doped optical fibres have considerable potential as near-IR active lasing media. This paper examines bismuth-doped fibres intended for the fabrication of fibre lasers and optical amplifiers and reviews recent results on the luminescence properties of various types of bismuth-doped fibres and the performance of bismuth-doped fibre lasers and optical amplifiers for the spectral range 1150 - 1550 nm. Problems are discussed that have yet to be solved in order to improve the efficiency of the bismuth lasers and optical amplifiers. (optical fibres, lasers and amplifiers. properties and applications)

  12. Airborne concentrations of peanut protein.

    PubMed

    Johnson, Rodney M; Barnes, Charles S

    2013-01-01

    Food allergy to peanut is a significant health problem, and there are reported allergic reactions to peanuts despite not eating or having physical contact with peanuts. It is presumed that an allergic reaction may have occurred from inhalation of airborne peanut allergens. The purpose of this study was to detect the possible concentrations of airborne peanut proteins for various preparations and during specific activities. Separate Ara h 1 and Ara h 2 monoclonal enzyme-linked immunosorbent assays and a polyclonal sandwich enzyme immunoassay for peanuts were used to detect the amount of airborne peanut protein collected using a Spincon Omni 3000 air collector (Sceptor Industries, Inc., Kansas City, MO) under different peanut preparation methods and situations. Air samples were measured for multiple peanut preparations and scenarios. Detectable amounts of airborne peanut protein were measured using a whole peanut immunoassay when removing the shells of roasted peanut. No airborne peanut allergen (Ara h 1 or Ara h 2) or whole peanut protein above the LLD was measured in any of the other peanut preparation collections. Ara h 1, Ara h 2, and polyclonal peanut proteins were detected from water used to boil peanuts. Small amounts of airborne peanut protein were detected in the scenario of removing shells from roasted peanuts; however, Ara h 1 and Ara h 2 proteins were unable to be consistently detected. Although airborne peanut proteins were detected, the concentration of airborne peanut protein that is necessary to elicit a clinical allergic reaction is unknown. PMID:23406937

  13. Airborne ballistic camera tracking systems

    NASA Technical Reports Server (NTRS)

    Redish, W. L.

    1976-01-01

    An operational airborne ballistic camera tracking system was tested for operational and data reduction feasibility. The acquisition and data processing requirements of the system are discussed. Suggestions for future improvements are also noted. A description of the data reduction mathematics is outlined. Results from a successful reentry test mission are tabulated. The test mission indicated that airborne ballistic camera tracking systems are feasible.

  14. Tunable Infrared Laser Instruments for Airborne Atmospheric Studies

    NASA Technical Reports Server (NTRS)

    Fried, A.; Diskin, G.; Weibring, P.; Richter, D.; Walega, J. G.; Sachse, G.; Slate, T.; Rana, M.; Podolske, J.

    2008-01-01

    Tunable infrared laser-based instruments on airborne platforms have provided invaluable contributions to atmospheric studies over the past several decades. This paper presents an overview of some recent studies and developments using this approach that were presented at the 2007 Field Laser Applications in Industry and Research (FLAIR, http://www.inoa.it/flair/) conference in Florence, Italy. The present overview only covers select in situ absorption-based instruments that were presented in the airborne session at this conference. In no case are comprehensive details presented. These details can be found in the numerous references given. Additional approaches based upon cavity-enhanced and photoacoustic measurements, which are also making invaluable contributions in airborne atmospheric studies, are not discussed in this brief overview.

  15. Airborne Trace Gas Mapping During the GOSAT-COMEX Experiment

    NASA Astrophysics Data System (ADS)

    Tratt, D. M.; Leifer, I.; Buckland, K. N.; Johnson, P. D.; Van Damme, M.; Pierre-Francois, C.; Clarisse, L.

    2015-12-01

    The GOSAT-COMEX-IASI (Greenhouse gases Observing SATellite - CO2 and Methane EXperiment - Infrared Atmospheric Sounding Interferometer) experiment acquired data on 24-27 April 2015 with two aircraft, a mobile ground-based sampling suite, and the GOSAT and IASI platforms. Collections comprised the Kern Front and Kern River oil fields north of Bakersfield, Calif. and the Chino stockyard complex in the eastern Los Angeles Basin. The nested-grid experiment examined the convergence of multiple approaches to total trace gas flux estimation from the experimental area on multiple length-scales, which entailed the integrated analysis of ground-based, airborne, and space-based measurements. Airborne remote sensing was employed to map the spatial distribution of discrete emission sites - crucial information to understanding their relative aggregate contribution to the overall flux estimation. This contribution discusses the methodology in the context of the airborne GHG source mapping component of the GOSAT-COMEX experiment and its application to satellite validation.

  16. Airborne transmission of lyssaviruses.

    PubMed

    Johnson, N; Phillpotts, R; Fooks, A R

    2006-06-01

    In 2002, a Scottish bat conservationist developed a rabies-like disease and subsequently died. This was caused by infection with European bat lyssavirus 2 (EBLV-2), a virus closely related to Rabies virus (RABV). The source of this infection and the means of transmission have not yet been confirmed. In this study, the hypothesis that lyssaviruses, particularly RABV and the bat variant EBLV-2, might be transmitted via the airborne route was tested. Mice were challenged via direct introduction of lyssavirus into the nasal passages. Two hours after intranasal challenge with a mouse-adapted strain of RABV (Challenge Virus Standard), viral RNA was detectable in the tongue, lungs and stomach. All of the mice challenged by direct intranasal inoculation developed disease signs by 7 days post-infection. Two out of five mice challenged by direct intranasal inoculation of EBLV-2 developed disease between 16 and 19 days post-infection. In addition, a simple apparatus was evaluated in which mice could be exposed experimentally to infectious doses of lyssavirus from an aerosol. Using this approach, mice challenged with RABV, but not those challenged with EBLV-2, were highly susceptible to infection by inhalation. These data support the hypothesis that lyssaviruses, and RABV in particular, can be spread by airborne transmission in a dose-dependent manner. This could present a particular hazard to personnel exposed to aerosols of infectious RABV following accidental release in a laboratory environment. PMID:16687600

  17. NASA's Airborne Astronomy Program - Lessons For SOFIA

    NASA Astrophysics Data System (ADS)

    Erickson, Edwin F.

    2007-07-01

    Airborne astronomy was pioneered and has evolved at NASA Ames Research Center near San Francisco, California, since 1965. Nowhere else in the world has a similar program been implemented. Its many unique features deserve description, especially for the benefit of planning the operation of SOFIA, the Stratospheric Observatory for Infrared Astronomy, and in particular since NASA Headquarters’ recent decision to base SOFIA operations at Dryden Flight Research Center at Edwards, California instead of at Ames. The history of Ames’ airborne astronomy program is briefly summarized. Discussed in more detail are the operations and organization of the 21-year Kuiper Airborne Observatory (KAO) program, which provide important lessons for SOFIA. The KAO program is our best prototype for planning effective SOFIA operations. Principal features of the KAO program which should be retained on SOFIA are: unique science, innovative new science instruments and technologies, training of young scientists, an effective education and public outreach program, flexibility, continuous improvement, and efficient operations with a lean, well integrated team. KAO program features which should be improved upon with SOFIA are: (1) a management structure that is dedicated primarily to safely maximizing scientific productivity for the resources available, headed by a scientist who is the observatory director, and (2) stimuli to assure prompt distribution and accessibility of data to the scientific community. These and other recommendations were recorded by the SOFIA Science Working Group in 1995, when the KAO was decommissioned to start work on SOFIA. Further operational and organizational factors contributing to the success of the KAO program are described. Their incorporation into SOFIA operations will help assure the success of this new airborne observatory. SOFIA is supported by NASA in the U.S. and DLR (the German Aerospace Center) in Germany.

  18. Performance Basis for Airborne Separation

    NASA Technical Reports Server (NTRS)

    Wing, David J.

    2008-01-01

    Emerging applications of Airborne Separation Assistance System (ASAS) technologies make possible new and powerful methods in Air Traffic Management (ATM) that may significantly improve the system-level performance of operations in the future ATM system. These applications typically involve the aircraft managing certain components of its Four Dimensional (4D) trajectory within the degrees of freedom defined by a set of operational constraints negotiated with the Air Navigation Service Provider. It is hypothesized that reliable individual performance by many aircraft will translate into higher total system-level performance. To actually realize this improvement, the new capabilities must be attracted to high demand and complexity regions where high ATM performance is critical. Operational approval for use in such environments will require participating aircraft to be certified to rigorous and appropriate performance standards. Currently, no formal basis exists for defining these standards. This paper provides a context for defining the performance basis for 4D-ASAS operations. The trajectory constraints to be met by the aircraft are defined, categorized, and assessed for performance requirements. A proposed extension of the existing Required Navigation Performance (RNP) construct into a dynamic standard (Dynamic RNP) is outlined. Sample data is presented from an ongoing high-fidelity batch simulation series that is characterizing the performance of an advanced 4D-ASAS application. Data of this type will contribute to the evaluation and validation of the proposed performance basis.

  19. Bismuth-Loaded Polymer Scintillators for Gamma Ray Spectroscopy

    SciTech Connect

    Rupert, B L; Cherepy, N J; Sturm, B W; Sanner, R D; Dai, Z; Payne, S A

    2011-04-11

    We synthesize a series of polyvinylcarbazole monoliths containing varying loadings of triphenyl bismuth as a high-Z dopant and varying fluors, either organic or organometallic, in order to study their use as scintillators capable of gamma ray spectroscopy. A trend of increasing bismuth loading resulting in a better-resolved photopeak is observed. For PVK parts with no fluor or a standard organic fluor, diphenylanthracene, increasing bismuth loading results in decreasing light yield while with samples 1 or 3 % by weight of the spin-orbit coupling organometallic fluor FIrpic, which emits light from both singlet and triple excitons, show increasing light yield with increasing bismuth loading. Our best performing PVK/ BiPh{sub 3}/FIrpic scintillator with 40 wt % BiPh3 and 3 wt % FIrpic has an emission maximum of 500 nm, a light yield of {approx}30,000 photons/MeV, and energy resolution better than 7% FWHM at 662 keV. Replacing the Ir complex with an equal weight of diphenylanthracene produces a sample with a light yield of {approx}6,000 photons/MeV, with an emission maximum at 420 nm and energy resolution of 9% at 662 keV. Transmission electron microscopy studies show that the BiPh{sub 3} forms small clusters of approximately 5 nm diameter.

  20. ADSORPTION-BISMUTH PHOSPHATE METHOD FOR SEPARATING PLUTONIUM

    DOEpatents

    Russell, E.R.; Adamson, A.W.; Boyd, G.E.

    1960-06-28

    A process is given for separating plutonium from uranium and fission products. Plutonium and uranium are adsorbed by a cation exchange resin, plutonium is eluted from the adsorbent, and then, after oxidation to the hexavalent state, the plutonium is contacted with a bismuth phosphate carrier precipitate.

  1. REMOVAL OF CERTAIN FISSION PRODUCT METALS FROM LIQUID BISMUTH COMPOSITIONS

    DOEpatents

    Dwyer, O.E.; Howe, H.E.; Avrutik, E.R.

    1959-11-24

    A method is described for purifying a solution of urarium in liquid bismuth containing at least one metal from the group consisting of selenium, tellurium, palladium, ruthenium, rhodium, niobium, and zirconium. The solution is contacted with zinc in an inert atmosphere to form a homogeneous melt, a solid zinc phase is formed, and the zinc phase containing the metal is separated from the melt.

  2. Lead-Bismuth Activities at the Karlsruhe Lead Laboratory KALLA

    SciTech Connect

    Knebel, Joachim U.; Muller, Georg; Konys, Jurgen

    2002-07-01

    At Forschungszentrum Karlsruhe (FZK) the characteristics of an accelerator-driven subcritical system (ADS) are evaluated, mainly with respect to the potential of transmutation of minor actinides and long-lived fission products, to the feasibility and to safety aspects. All experimental activities, which are related to lead-bismuth as cooling fluid and spallation material, are performed in the Karlsruhe Lead Laboratory KALLA. This article gives an overview on KALLA, which has three stagnant experiments and three loop experiments. The stagnant experiments are concentrating on corrosion mechanisms, surface treatment, oxygen sensor development, and oxygen control system (OCS), the loop experiments are concentrating on thermalhydraulic measurement techniques, ADS-relevant component testing, and corrosion investigations in flowing lead-bismuth. A fourth loop experiment is planned to investigate the integral heat removal from a 4 MW spallation target for normal and decay heat removal conditions. Among others, latest results are presented of: characteristics of oxygen sensors in flowing liquid Pb-Bi, the oxygen control system (OCS) operating on a loop system, an ultrasonic flow meter applied to lead-bismuth at 400 deg. C. In addition, results are given on the improvement of the corrosion resistivity of steels in flowing lead-bismuth, using a special temperature treatment method (electron beam facility GESA) and alloying aluminium in the surface layer. (authors)

  3. Discovery of the thallium, lead, bismuth, and polonium isotopes

    NASA Astrophysics Data System (ADS)

    Fry, C.; Thoennessen, M.

    2013-05-01

    Forty-two thallium, forty-two lead, forty-one bismuth, and forty-two polonium isotopes have so far been observed; the discovery of these isotopes is described. For each isotope a brief summary of the first refereed publication, including the production and identification method, is presented.

  4. A simplified analytical method to estimate the bismuth build-up and the polonium activity in LiPb-bearing blankets of a fusion reactor

    SciTech Connect

    Zimin, S.

    1994-09-01

    Although neutron-induced activation in a fusion reactor is a nonlinear problem whose solution requires the use of both neutron transport and activation codes, a simplified analytical approach to bismuth and polonium build-up in lead is proposed to estimate the polonium inventory and the related biological hazards of LiPb-bearing blankets. All neutronic reactions of polonium build-up in lead and in its bismuth impurities are surveyed and discussed. The contribution of the different possible chains to the build-up of polonium is evaluated. A set of differential equations for the densities of {sup 209}Bi and {sup 210}Po isotopes in the lead is worked into simplified, easy-to-use expressions. These analytical formulas obtained for the densities can be used for the estimation of both the bismuth and the polonium densities after any reactor operation time and allow identification of the build-up mechanisms of those isotopes. A simplified formula for polonium inventory estimations at any blanket zone is proposed as well. The polonium inventory evaluation takes into account the initial conditions (primarily bismuth impurity in the lead) and the reactor operation conditions, such as the average availability of a fusion reactor and the blanket operation scenario. 44 refs., 11 figs., 5 tabs.

  5. Bismuth tri-iodide radiation detector development

    NASA Astrophysics Data System (ADS)

    Gokhale, Sasmit S.

    Bismuth tri-iodide is an attractive material for room temperature radiation detection. BiI3 demonstrates a number of properties that are apt for semiconductor radiation detection, especially gamma ray spectroscopy. The high atomic number (ZBi = 83 and ZI = 53) and the relatively high density (5.78 g/cm3) cause the material to have good photon stopping power, while the large band-gap (1.67 eV ) allows it to function as a room temperature radiation detector without any cooling mechanism. This work presents the fabrication and characterization of BiI3 radiation detectors. For the purpose of this research detectors were fabricated by cutting BiI3 crystal boules, followed by mechanical and chemical surface treatments. Detectors with various electrode geometries enabling single polarity charge sensing were fabricated. The electrical characteristics and the radiation response of the detectors were measured. The radiation response measurement was performed at room temperature using a 241Am alpha particle source and a 241Am sealed gamma-ray source. The spectral resolutions of the detectors varied from 2.09% - 6.1% for 59.5 keV gamma-rays and between 26% - 40% for 5.48 MeV alpha particles. Charge carrier properties such as the electron and hole mobility and lifetime were also estimated. The electron mobility for an ultrapure BiI 3 detector was estimated to be approximately 433 cm 2/Vs while that for antimony doped BiI3 was estimated to be around 956 cm2/Vs and the mobility-lifetime product for electrons was estimated to be around 5.44 x 10-4 cm 2/V. Detector simulation was performed using the Monte Carlo simulation code MCNP5. A Matlab script which incorporates charge carrier trapping and statistical variation was written to generate a gamma-ray spectrum from the simulated energy deposition spectra. Measured and simulated spectra were compared to extract the charge carrier mobility-lifetime products, which for electrons and holes were estimated to be 5 x 10-3 cm2/V and 1.3 x

  6. Bismuth-based oxide semiconductors: Mild synthesis and practical applications

    NASA Astrophysics Data System (ADS)

    Timmaji, Hari Krishna

    In this dissertation study, bismuth based oxide semiconductors were prepared using 'mild' synthesis techniques---electrodeposition and solution combustion synthesis. Potential environmental remediation and solar energy applications of the prepared oxides were evaluated. Bismuth vanadate (BiVO4) was prepared by electrodeposition and solution combustion synthesis. A two step electrosynthesis strategy was developed and demonstrated for the first time. In the first step, a Bi film was first electrodeposited on a Pt substrate from an acidic BiCl3 medium. Then, this film was anodically stripped in a medium containing hydrolyzed vanadium precursor, to generate Bi3+, and subsequent BiVO4 formation by in situ precipitation. The photoelectrochemical data were consistent with the in situ formation of n-type semiconductor films. In the solution combustion synthesis procedure, BiVO4 powders were prepared using bismuth nitrate pentahydrate as the bismuth precursor and either vanadium chloride or vanadium oxysulfate as the vanadium precursor. Urea, glycine, or citric acid was used as the fuel. The effect of the vanadium precursor on the photocatalytic activity of combustion synthesized BiVO 4 was evaluated in this study. Methyl orange was used as a probe to test the photocatalytic attributes of the combustion synthesized (CS) samples, and benchmarked against a commercial bismuth vanadate sample. The CS samples showed superior activity to the commercial benchmark sample, and samples derived from vanadium chloride were superior to vanadium oxysulfate counterparts. The photoelectrochemical properties of the various CS samples were also studied and these samples were shown to be useful both for environmental photocatalytic remediation and water photooxidation applications. Silver bismuth tungstate (AgBiW2O8) nanoparticles were prepared for the first time by solution combustion synthesis by using silver nitrate, bismuth nitrate, sodium tungstate as precursors for Ag, Bi, and W

  7. Processor architecture for airborne SAR systems

    NASA Technical Reports Server (NTRS)

    Glass, C. M.

    1983-01-01

    Digital processors for spaceborne imaging radars and application of the technology developed for airborne SAR systems are considered. Transferring algorithms and implementation techniques from airborne to spaceborne SAR processors offers obvious advantages. The following topics are discussed: (1) a quantification of the differences in processing algorithms for airborne and spaceborne SARs; and (2) an overview of three processors for airborne SAR systems.

  8. Evaluation of meteorological airborne Doppler radar

    NASA Technical Reports Server (NTRS)

    Hildebrand, P. H.; Mueller, C. K.

    1984-01-01

    This paper will discuss the capabilities of airborne Doppler radar for atmospheric sciences research. The evaluation is based on airborne and ground based Doppler radar observations of convective storms. The capability of airborne Doppler radar to measure horizontal and vertical air motions is evaluated. Airborne Doppler radar is shown to be a viable tool for atmospheric sciences research.

  9. Airborne agent concentration analysis

    DOEpatents

    Gelbard, Fred

    2004-02-03

    A method and system for inferring airborne contaminant concentrations in rooms without contaminant sensors, based on data collected by contaminant sensors in other rooms of a building, using known airflow interconnectivity data. The method solves a least squares problem that minimizes the difference between measured and predicted contaminant sensor concentrations with respect to an unknown contaminant release time. Solutions are constrained to providing non-negative initial contaminant concentrations in all rooms. The method can be used to identify a near-optimal distribution of sensors within the building, when then number of available sensors is less than the total number of rooms. This is achieved by having a system-sensor matrix that is non-singular, and by selecting that distribution which yields the lowest condition number of all the distributions considered. The method can predict one or more contaminant initial release points from the collected data.

  10. Airborne Wind Turbine

    SciTech Connect

    2010-09-01

    Broad Funding Opportunity Announcement Project: Makani Power is developing an Airborne Wind Turbine (AWT) that eliminates 90% of the mass of a conventional wind turbine and accesses a stronger, more consistent wind at altitudes of near 1,000 feet. At these altitudes, 85% of the country can offer viable wind resources compared to only 15% accessible with current technology. Additionally, the Makani Power wing can be economically deployed in deep offshore waters, opening up a resource which is 4 times greater than the entire U.S. electrical generation capacity. Makani Power has demonstrated the core technology, including autonomous launch, land, and power generation with an 8 meter wingspan, 20 kW prototype. At commercial scale, Makani Power aims to develop a 600 kW, 28 meter wingspan product capable of delivering energy at an unsubsidized cost competitive with coal, the current benchmark for low-cost power.

  11. Airborne Cloud Computing Environment (ACCE)

    NASA Technical Reports Server (NTRS)

    Hardman, Sean; Freeborn, Dana; Crichton, Dan; Law, Emily; Kay-Im, Liz

    2011-01-01

    Airborne Cloud Computing Environment (ACCE) is JPL's internal investment to improve the return on airborne missions. Improve development performance of the data system. Improve return on the captured science data. The investment is to develop a common science data system capability for airborne instruments that encompasses the end-to-end lifecycle covering planning, provisioning of data system capabilities, and support for scientific analysis in order to improve the quality, cost effectiveness, and capabilities to enable new scientific discovery and research in earth observation.

  12. Characterization of Airborne Bacteria at an Underground Subway Station

    PubMed Central

    Dybwad, Marius; Granum, Per Einar; Bruheim, Per

    2012-01-01

    The reliable detection of airborne biological threat agents depends on several factors, including the performance criteria of the detector and its operational environment. One step in improving the detector's performance is to increase our knowledge of the biological aerosol background in potential operational environments. Subway stations are enclosed public environments, which may be regarded as potential targets for incidents involving biological threat agents. In this study, the airborne bacterial community at a subway station in Norway was characterized (concentration level, diversity, and virulence- and survival-associated properties). In addition, a SASS 3100 high-volume air sampler and a matrix-assisted laser desorption ionization–time of flight mass spectrometry-based isolate screening procedure was used for these studies. The daytime level of airborne bacteria at the station was higher than the nighttime and outdoor levels, and the relative bacterial spore number was higher in outdoor air than at the station. The bacterial content, particle concentration, and size distribution were stable within each environment throughout the study (May to September 2010). The majority of the airborne bacteria belonged to the genera Bacillus, Micrococcus, and Staphylococcus, but a total of 37 different genera were identified in the air. These results suggest that anthropogenic sources are major contributors to airborne bacteria at subway stations and that such airborne communities could harbor virulence- and survival-associated properties of potential relevance for biological detection and surveillance, as well as for public health. Our findings also contribute to the development of realistic testing and evaluation schemes for biological detection/surveillance systems by providing information that can be used to mimic real-life operational airborne environments in controlled aerosol test chambers. PMID:22247150

  13. Characterization of airborne bacteria at an underground subway station.

    PubMed

    Dybwad, Marius; Granum, Per Einar; Bruheim, Per; Blatny, Janet Martha

    2012-03-01

    The reliable detection of airborne biological threat agents depends on several factors, including the performance criteria of the detector and its operational environment. One step in improving the detector's performance is to increase our knowledge of the biological aerosol background in potential operational environments. Subway stations are enclosed public environments, which may be regarded as potential targets for incidents involving biological threat agents. In this study, the airborne bacterial community at a subway station in Norway was characterized (concentration level, diversity, and virulence- and survival-associated properties). In addition, a SASS 3100 high-volume air sampler and a matrix-assisted laser desorption ionization-time of flight mass spectrometry-based isolate screening procedure was used for these studies. The daytime level of airborne bacteria at the station was higher than the nighttime and outdoor levels, and the relative bacterial spore number was higher in outdoor air than at the station. The bacterial content, particle concentration, and size distribution were stable within each environment throughout the study (May to September 2010). The majority of the airborne bacteria belonged to the genera Bacillus, Micrococcus, and Staphylococcus, but a total of 37 different genera were identified in the air. These results suggest that anthropogenic sources are major contributors to airborne bacteria at subway stations and that such airborne communities could harbor virulence- and survival-associated properties of potential relevance for biological detection and surveillance, as well as for public health. Our findings also contribute to the development of realistic testing and evaluation schemes for biological detection/surveillance systems by providing information that can be used to mimic real-life operational airborne environments in controlled aerosol test chambers. PMID:22247150

  14. Open Source Software Reuse in the Airborne Cloud Computing Environment

    NASA Astrophysics Data System (ADS)

    Khudikyan, S. E.; Hart, A. F.; Hardman, S.; Freeborn, D.; Davoodi, F.; Resneck, G.; Mattmann, C. A.; Crichton, D. J.

    2012-12-01

    Earth science airborne missions play an important role in helping humans understand our climate. A challenge for airborne campaigns in contrast to larger NASA missions is that their relatively modest budgets do not permit the ground-up development of data management tools. These smaller missions generally consist of scientists whose primary focus is on the algorithmic and scientific aspects of the mission, which often leaves data management software and systems to be addressed as an afterthought. The Airborne Cloud Computing Environment (ACCE), developed by the Jet Propulsion Laboratory (JPL) to support Earth Science Airborne Program, is a reusable, multi-mission data system environment for NASA airborne missions. ACCE provides missions with a cloud-enabled platform for managing their data. The platform consists of a comprehensive set of robust data management capabilities that cover everything from data ingestion and archiving, to algorithmic processing, and to data delivery. Missions interact with this system programmatically as well as via browser-based user interfaces. The core components of ACCE are largely based on Apache Object Oriented Data Technology (OODT), an open source information integration framework at the Apache Software Foundation (ASF). Apache OODT is designed around a component-based architecture that allows for selective combination of components to create highly configurable data management systems. The diverse and growing community that currently contributes to Apache OODT fosters on-going growth and maturation of the software. ACCE's key objective is to reduce cost and risks associated with developing data management systems for airborne missions. Software reuse plays a prominent role in mitigating these problems. By providing a reusable platform based on open source software, ACCE enables airborne missions to allocate more resources to their scientific goals, thereby opening the doors to increased scientific discovery.

  15. Surface morphology and Raman spectroscopy of thin layers of antimony and bismuth chalcogenides

    NASA Astrophysics Data System (ADS)

    Luk'yanova, L. N.; Bibik, A. Yu.; Aseev, V. A.; Usov, O. A.; Makarenko, I. V.; Petrov, V. N.; Nikonorov, N. V.; Kutasov, V. A.

    2016-07-01

    The phonon spectra in thin layers of bismuth telluride and solid solutions of Bi2- x Sb x Te3- y Se y of different composition, belonging to three-dimensional topological insulators, have been investigated by micro-Raman spectroscopy, and the morphology of an interlayer van der Waals (0001) surface in them has been studied by semicontact atomic force microscopy at room temperature. The analysis of the Raman spectra and the intensity ratio of active and inactive longitudinal optical modes depending on the composition, morphology of the interlayer surface, and thickness of the layers enabled the estimation of the effect of topological surface states of Dirac fermions, associated with the strengthening of the electron-phonon interaction as a result of resonance Raman scattering, and the identification of the compositions, in which the contribution of topological surface states becomes dominant.

  16. Airborne Particulate Threat Assessment

    SciTech Connect

    Patrick Treado; Oksana Klueva; Jeffrey Beckstead

    2008-12-31

    Aerosol threat detection requires the ability to discern between threat agents and ambient background particulate matter (PM) encountered in the environment. To date, Raman imaging technology has been demonstrated as an effective strategy for the assessment of threat agents in the presence of specific, complex backgrounds. Expanding our understanding of the composition of ambient particulate matter background will improve the overall performance of Raman Chemical Imaging (RCI) detection strategies for the autonomous detection of airborne chemical and biological hazards. Improving RCI detection performance is strategic due to its potential to become a widely exploited detection approach by several U.S. government agencies. To improve the understanding of the ambient PM background with subsequent improvement in Raman threat detection capability, ChemImage undertook the Airborne Particulate Threat Assessment (APTA) Project in 2005-2008 through a collaborative effort with the National Energy Technology Laboratory (NETL), under cooperative agreement number DE-FC26-05NT42594. During Phase 1 of the program, a novel PM classification based on molecular composition was developed based on a comprehensive review of the scientific literature. In addition, testing protocols were developed for ambient PM characterization. A signature database was developed based on a variety of microanalytical techniques, including scanning electron microscopy, FT-IR microspectroscopy, optical microscopy, fluorescence and Raman chemical imaging techniques. An automated particle integrated collector and detector (APICD) prototype was developed for automated collection, deposition and detection of biothreat agents in background PM. During Phase 2 of the program, ChemImage continued to refine the understanding of ambient background composition. Additionally, ChemImage enhanced the APICD to provide improved autonomy, sensitivity and specificity. Deliverables included a Final Report detailing our

  17. Airborne Gravity Data Enhances NGS Experimental Gravimetric Geoid in Alaska

    NASA Astrophysics Data System (ADS)

    Holmes, S. A.; Childers, V. A.; Li, X.; Roman, D. R.

    2014-12-01

    The U.S. National Geodetic Survey [NGS], through their Gravity for the Redefinition of the American Vertical Datum [GRAV-D] program, continues to update its gravimetry holdings by flying new airborne gravity surveys over a large fraction of the USA and its territories. By 2022, NGS intends that all orthometric heights in the USA will be determined in the field by using a reliable national gravimetric geoid model to transform from geodetic heights obtained from GPS. Several airborne campaigns have already been flown over Alaska and its coastline. Some of this Alaskan coastal data have been incorporated into a new NGS experimental geoid model - xGEOID14. The xGEOID14 model is the first in a series of annual experimental geoid models that will incorporate NGS GRAV-D airborne data. This series provides a useful benchmark for assessing and improving current techniques by which the airborne and land-survey data are filtered and cleaned, and then combined with satellite gravity models, elevation data (etc.) with the ultimate aim of computing a geoid model that can support a national physical height system by 2022. Here we will examine the NGS GRAV-D airborne data in Alaska, and assess its contribution to xGEOID14. Future prospects for xGEOID15 will also be considered.

  18. Airborne rescue system

    NASA Technical Reports Server (NTRS)

    Haslim, Leonard A. (Inventor)

    1991-01-01

    The airborne rescue system includes a boom with telescoping members for extending a line and collar to a rescue victim. The boom extends beyond the tip of the helicopter rotor so that the victim may avoid the rotor downwash. The rescue line is played out and reeled in by winch. The line is temporarily retained under the boom. When the boom is extended, the rescue line passes through clips. When the victim dons the collar and the tension in the line reaches a predetermined level, the clips open and release the line from the boom. Then the rescue line can form a straight line between the victim and the winch, and the victim can be lifted to the helicopter. A translator is utilized to push out or pull in the telescoping members. The translator comprises a tape and a rope. Inside the telescoping members the tape is curled around the rope and the tape has a tube-like configuration. The tape and rope are provided from supply spools.

  19. METHOD OF PREPARING URANIUM, THORIUM, OR PLUTONIUM OXIDES IN LIQUID BISMUTH

    DOEpatents

    Davidson, J.K.; Robb, W.L.; Salmon, O.N.

    1960-11-22

    A method is given for forming compositions, as well as the compositions themselves, employing uranium hydride in a liquid bismuth composition to increase the solubility of uranium, plutonium and thorium oxides in the liquid bismuth. The finely divided oxide of uranium, plutonium. or thorium is mixed with the liquid bismuth and uranium hydride, the hydride being present in an amount equal to about 3 at. %, heated to about 5OO deg C, agitated and thereafter cooled and excess resultant hydrogen removed therefrom.

  20. Dielectric spectra of bismuth vanadate Bi4V2O11

    NASA Astrophysics Data System (ADS)

    Borisov, V. N.; Pashkov, V. M.; Poplavko, Iu. M.; Avakian, P. B.; Osipian, V. G.

    1990-06-01

    Results of a study of the temperature-frequency dependence of the behavior of the dielectric parameters of bismuth vanadate, Bi4V2O11, in the frequency range 1-100 GHz are reported. It is shown that bismuth vanadate is characterized by a large number of phase transitions. Yet another, previously unknown, phase transition in bismuth vanadate, masked by a relaxation process, has been observed in the temperature range 410-420 K.

  1. Bismuth-doped germanosilicate fibre laser with 20-W output power at 1460 nm

    SciTech Connect

    Firstov, Sergei V; Shubin, Aleksei V; Khopin, V F; Mel'kumov, Mikhail A; Bufetov, Igor' A; Medvedkov, O I; Gur'yanov, Aleksei N; Dianov, Evgenii M

    2011-07-31

    We report the first cw bismuth - germanium codoped silica fibre laser with an output power above 20 W at 1460 nm and 50% optical efficiency. The laser operates on a transition between energy levels of bismuth-related active centres associated with silicon. The incorporation of a small amount ({approx}5 mol %) of germanium into the core of bismuth-doped silica fibre has little effect on its luminescence spectrum but reduces optical losses, which limit the laser efficiency. (letters)

  2. Mapping permafrost with airborne electromagnetics

    NASA Astrophysics Data System (ADS)

    Minsley, B. J.; Ball, L. B.; Bloss, B. R.; Kass, A.; Pastick, N.; Smith, B. D.; Voss, C. I.; Walsh, D. O.; Walvoord, M. A.; Wylie, B. K.

    2014-12-01

    Permafrost is a key characteristic of cold region landscapes, yet detailed assessments of how the subsurface distribution of permafrost impacts the environment, hydrologic systems, and infrastructure are lacking. Data acquired from several airborne electromagnetic (AEM) surveys in Alaska provide significant new insight into the spatial extent of permafrost over larger areas (hundreds to thousands of square kilometers) than can be mapped using ground-based geophysical methods or through drilling. We compare several AEM datasets from different areas of interior Alaska, and explore the capacity of these data to infer geologic structure, permafrost extent, and related hydrologic processes. We also assess the impact of fires on permafrost by comparing data from different burn years within similar geological environments. Ultimately, interpretations rely on understanding the relationship between electrical resistivity measured by AEM surveys and the physical properties of interest such as geology, permafrost, and unfrozen water content in the subsurface. These relationships are often ambiguous and non-unique, so additional information is useful for reducing uncertainty. Shallow (upper ~1m) permafrost and soil characteristics identified from remotely sensed imagery and field observations help to constrain and aerially extend near-surface AEM interpretations, where correlations between the AEM and remote sensing data are identified using empirical multivariate analyses. Surface nuclear magnetic resonance (sNMR) measurements quantify the contribution of unfrozen water at depth to the AEM-derived electrical resistivity models at several locations within one survey area. AEM surveys fill a critical data gap in the subsurface characterization of permafrost environments and will be valuable in future mapping and monitoring programs in cold regions.

  3. Chrysanthemum-like bismuth sulfide microcrystals: Synthesis, characterization, and properties

    NASA Astrophysics Data System (ADS)

    Jiang, Jinghui; Gao, Guanhua; Yu, Runnan; Qiu, Guanzhou; Liu, Xiaohe

    2011-02-01

    Uniform chrysanthemum-like bismuth sulfide (Bi 2S 3) microcrystals assembled from nanosheet building blocks were successfully synthesized via a convenient hydrothermal synthetic route under mild conditions in which hydrated bismuth nitrate and L-cysteine were employed to supply Bi and S source and ethylenediaminetetraacetic acid disodium salt (EDTA-Na 2) was employed as chelating agent. The influences of reaction temperatures and time on the morphologies of final products were investigated. The phase structures, morphologies, and properties of as-prepared products were investigated by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, high-resolution transmission electron microscope, and photoluminescence spectra. The possible growth mechanism for the formation of chrysanthemum-like Bi 2S 3 microcrystals was discussed on the basis of the experimental results.

  4. Coexistence of multiple metastable polytypes in rhombohedral bismuth

    PubMed Central

    Shu, Yu; Hu, Wentao; Liu, Zhongyuan; Shen, Guoyin; Xu, Bo; Zhao, Zhisheng; He, Julong; Wang, Yanbin; Tian, Yongjun; Yu, Dongli

    2016-01-01

    Derivative structural polytypes coexisting with the rhombohedral A7 structure of elemental bismuth (Bi) have been discovered at ambient condition, based on microstructure analyses of pure Bi samples treated under high pressure and high temperature conditions. Three structures with atomic positions close to those of the A7 structure have been identified through first-principles calculations, showing these polytypes energetically comparable to the A7 structure under ambient condition. Simulated diffraction data are in excellent agreement with the experimental observations. We argue that previously reported some variations of physical properties (e.g., density, electrical conductivity, and magnetism) in bismuth could be due to the formation of these polytypes. The coexistence of metastable derivative structural polytypes may be a widely occurring phenomenon in other elemental materials. PMID:26883895

  5. The Design and Fabrication of Bismuth Hall Effect Biosensors

    NASA Astrophysics Data System (ADS)

    Sigillito, A. J.; Rudolph, M.; Soghomonian, V.; Heremans, J. J.

    2011-03-01

    Because of their high sensitivity, accuracy, and low cost, the use of Hall biosensors promises to be an effective diagnostic technique that may aid in the early diagnosis of diseases. In this research, Hall sensors were fabricated from thermally evaporated bismuth thin films. The bismuth films were deposited under high vacuum onto heated Si/ Si O2 substrates using a two layer deposition technique. The films varied in thickness from 60 nm to 75 nm and were etched into Hall bar geometries using photolithography and wet chemical etching. Magnetoresistance and Hall measurements were taken from 4 K to 300 K. The data indicate that the sensors may be characterized using a two carrier model with high mobility, low density holes and low mobility, high density electrons. Additionally, the sensors were exposed to magnetite nanoparticles and characterized using atomic force microscopy. The results will be reported. This research was funded by the National Science Foundation (NSF Grant DMR-0851662).

  6. The Design and Fabrication of Bismuth Hall Effect Biosensors

    NASA Astrophysics Data System (ADS)

    Sigillito, Anthony; Rudolph, Martin; Soghomonian, Vicki; Heremans, J. J.

    2010-10-01

    Because of their high sensitivity, accuracy, and low cost, the use of Hall biosensors promises to be an effective diagnostic technique that may aid in the early diagnosis of diseases. In this research, Hall sensors were fabricated from thermally evaporated bismuth thin films. The bismuth films were deposited under high vacuum onto heated Si/SiO2 substrates using a two layer deposition technique. The films varied in thickness from 60 nm to 75 nm and were etched into Hall bar geometries using photolithography and wet chemical etching. Magnetoresistance and Hall measurements were taken from 4 K to 300 K. The data indicate that the sensors may be characterized using a two carrier model with high mobility, low density holes and low mobility, high density electrons. Additionally, the sensors were exposed to magnetite nanoparticles and characterized using atomic force microscopy. The results will be reported. This research was funded by the National Science Foundation (NSF Grant DMR-0851662).

  7. Shape-controlled solvothermal synthesis of bismuth subcarbonate nanomaterials

    NASA Astrophysics Data System (ADS)

    Cheng, Gang; Yang, Hanmin; Rong, Kaifeng; Lu, Zhong; Yu, Xianglin; Chen, Rong

    2010-08-01

    Much effort has been devoted to the synthesis of novel nanostructured materials because of their unique properties and potential applications. Bismuth subcarbonate ((BiO) 2CO 3) is one of commonly used antibacterial agents against Helicobacter pylori ( H. pylori). Different (BiO) 2CO 3 nanostructures such as cube-like nanoparticles, nanobars and nanoplates, were fabricated from bismuth nitrate via a simple solvothermal method. The nanostructures were characterized by powder X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM). It was found that the solvents and precursors have an influence on the morphologies of (BiO) 2CO 3 nanostructures. The possible formation mechanism of different (BiO) 2CO 3 nanostructures fabricated under different conditions was also discussed.

  8. Bismuth shielding during CT exams: a literature review.

    PubMed

    Morford, Kyle; Watts, Lynette K

    2012-01-01

    Dose-reducing techniques and patients' radiation protection are of more concern today than in the past with the increased dose used in multi-detector computed tomography (MDCT) compared to single detector scanners. Companies that produce MDCT scanners can, and most often do, apply software that complies with the as low as reasonably achievable (ALARA) principle and decreases the dose used for the imaging. New ways have been discovered to reduce the dose to patients' radiosensitive organs through in-plane bismuth shielding. Different sizes and thicknesses of the shields are available to cover patients more radiosensitive organs. This literature review describes the uses, benefits, and some concerns of in-plane bismuth shielding. PMID:22720541

  9. Tin-silver-bismuth solders for electronics assembly

    DOEpatents

    Vianco, P.T.; Rejent, J.A.

    1995-08-08

    A lead-free solder alloy is disclosed for electronic assemblies composed of a eutectic alloy of tin and silver with a bismuth addition, x, of 0bismuth added to the eutectic tin-silver alloy as determined by DSC analysis, 10 C/min. A preferred alloy composition is 91.84Sn-3.33Ag-4.83Bi (weight percent based on total alloy weight). 4 figs.

  10. Tin-silver-bismuth solders for electronics assembly

    DOEpatents

    Vianco, Paul T.; Rejent, Jerome A.

    1995-01-01

    A lead-free solder alloy for electronic assemblies composed of a eutectic alloy of tin and silver with a bismuth addition, x, of 0bismuth added to the eutectic tin-silver alloy as determined by DSC analysis, 10.degree. C./min. A preferred alloy composition is 91.84Sn-3.33Ag-4.83Bi (weight percent based on total alloy weight).

  11. Bismuth(III) deferiprone effectively inhibits growth of Desulfovibrio desulfuricans ATCC 27774.

    PubMed

    Barton, Larry L; Lyle, Daniel A; Ritz, Nathaniel L; Granat, Alex S; Khurshid, Ali N; Kherbik, Nada; Hider, Robert; Lin, Henry C

    2016-04-01

    Sulfate-reducing bacteria have been implicated in inflammatory bowel diseases and ulcerative colitis in humans and there is an interest in inhibiting the growth of these sulfide-producing bacteria. This research explores the use of several chelators of bismuth to determine the most effective chelator to inhibit the growth of sulfate-reducing bacteria. For our studies, Desulfovibrio desulfuricans ATCC 27774 was grown with nitrate as the electron acceptor and chelated bismuth compounds were added to test for inhibition of growth. Varying levels of inhibition were attributed to bismuth chelated with subsalicylate or citrate but the most effective inhibition of growth by D. desulfuricans was with bismuth chelated by deferiprone, 3-hydroxy-1,2-dimethyl-4(1H)-pyridone. Growth of D. desulfuricans was inhibited by 10 μM bismuth as deferiprone:bismuth with either nitrate or sulfate respiration. Our studies indicate deferiprone:bismuth has bacteriostatic activity on D. desulfuricans because the inhibition can be reversed following exposure to 1 mM bismuth for 1 h at 32 °C. We suggest that deferiprone is an appropriate chelator for bismuth to control growth of sulfate-reducing bacteria because deferiprone is relatively nontoxic to animals, including humans, and has been used for many years to bind Fe(III) in the treatment of β-thalassemia. PMID:26896170

  12. METHOD OF SEPARATING FISSION PRODUCTS FROM FUSED BISMUTH-CONTAINING URANIUM

    DOEpatents

    Wiswall, R.H.

    1958-06-24

    A process is described for removing metal selectively from liquid metal compositions. The method effects separation of flssion product metals selectively from dilute solution in fused bismuth, which contains uraniunn in solution without removal of more than 1% of the uranium. The process comprises contacting the fused bismuth with a fused salt composition consisting of sodium, potassium and lithium chlorides, adding to fused bismuth and molten salt a quantity of bismuth chloride which is stoichiometrically required to convert the flssion product metals to be removed to their chlorides which are more stable in the fused salt than in the molten metal and are, therefore, preferentially taken up in the fused salt phase.

  13. Inclusive measurement of (p,. pi. /sup -/xn) double charge exchange reactions on bismuth from threshold to 800 MeV

    SciTech Connect

    Dombsky, M.; D'Auria, J.M.; Kelson, I.; Yavin, A.I.; Ward, T.E.; Clark, J.L.; Ruth, T.; Sheffer, G.

    1985-07-01

    The energy dependence of the total angle-integrated cross section for the production of astatine isotopes from (p,..pi../sup -/xn) double charge exchange reactions on bismuth (/sup 209/Bi) was measured from 120 to 800 MeV using activation and radiochemical techniques. Chemical yields were estimated by direct radioassaying of /sup 211/At activity in thin (approx.1 mg/cm/sup 2/), irradiated bismuth targets. Calculations of the contributions of secondary (two-step) reactions to these measured astatine yields were performed, based partially upon the observed /sup 211/At activity although even at the highest energies, the contribution to products lighter than /sup 207/At was negligible. These data for products with as many as seven neutrons removed from the doubly coherent product (/sup 210/At) display nearly Gaussian shapes for the mass distributions of the astatine residues, with the maximum occurring for about /sup 204/At. The most probable momentum transfer deduced from these distributions for the initial ..pi../sup -/ production step was 335 MeV/c. The observed excitation functions display a behavior similar to that observed for the yield of /sup 210/Po from a (p,..pi../sup 0/) reaction on /sup 209/Bi, but radically different from that observed for inclusive ..pi../sup -/ reactions on a heavy nucleus. These data are discussed in terms of recent theoretical approaches to negative pion production from bismuth. In addition, a simple, schematic model is developed to treat the rapidly decreasing percentage of the total inclusive ..pi../sup -/ emission which is observed for this double charge exchange reaction. This model reflects the opacity of a nucleus to a source of internal energetic protons.

  14. Bismuth-based Superconducting Wires for Actual Implementation

    NASA Astrophysics Data System (ADS)

    Kobayashi, Shin-Ichi; Nakashima, Takayoshi; Yamazaki, Kohei; Sato, Ken-Ichi

    The bismuth-based superconducting wires (Bi-2223) have been produced as commercial products since 2004. Bi-2223 superconducting wires have been applied to cables, motors, magnets, and current leads. In particular, current leads have been used in a large accelerator, and magnets have been used in a B-H curve tracer for permanent magnets and magnetic billet heaters for hot extrusion. Motors and cables have been developed and evaluated as real sized apparatus.

  15. Weak antilocalization and UCFs in an open bismuth quantum dot

    NASA Astrophysics Data System (ADS)

    Hackens, B.; Minet, J. P.; Farhi, G.; Faniel, G.; Gustin, C.; Bayot, V.

    2003-04-01

    We report on the observation of weak antilocalization and universal conductance fluctuations in the magnetoconductance of an open quasi-ballistic bismuth nano-cavity. The electron decoherence length is comparable to sample dimensions at low temperature, while the spin-orbit coupling length is smaller. The temperature dependence of both the conductance and the dephasing length are consistent with two-dimensional electron-electron interactions being the dominant decoherence process.

  16. Solid solutions based on bismuth and antimony tellurides andbismuth selenides

    SciTech Connect

    Abrikosov, N.K.; Stasova, M.M.

    1986-05-01

    The phase diagrams of the systems Bi-Te, Bi-Se, and Sb-Te serve as a basis for constructing multiphase diagrams of ternary semiconductor systems. This paper studies layered structures with large unit-cell parameters in the regions of the solid solutions to explain the ordering processes in the solid solutions of semiconductor and intermetallic systems. The laws governing the formation and structral features of bismuth and antimony chalcogenides are studied to obtain thermoelectric materials and identification of minerals.

  17. Bismuth iron titanate pyrochlores: Thermostability, structure and properties

    SciTech Connect

    Piir, I.V.; Koroleva, M.S.; Ryabkov, Yu.I.; Korolev, D.A.; Chezhina, N.V.; Semenov, V.G.; Panchuk, V.V.

    2013-08-15

    Iron containing bismuth titanates with pyrochlore structure Bi{sub 1.6}Fe{sub x}Ti{sub 2}O{sub 7−δ}, where 0.08≤x≤0.4, were obtained by ceramic procedure. The results of bough pycnometric density of the pyrochlores and of X-ray powder diffraction structure refinement points to the preference for iron atoms to occupy the Bi{sup 3+}-sites. Electric and magnetic properties were studied for single phase pyrochlores based on bismuth titanates. The magnetic ordering was studied by the methods of Mössbauer spectroscopy and magnetic susceptibility. - Graphical abstract: The ideal crystal structure of pyrochlore A{sub 2}B{sub 2}O{sub 6}O' (A—Bi{sup 3+}, Fe{sup 3+}; B—Ti{sup 4+}, Fe{sup 3+}). Highlights: • Bismuth titanate pyrochlores stable over a wide temperature range were obtained. • The distribution of Fe{sup 3+} over various sites was determined. • The obtained systems were characterized by magnetic susceptibility, Mössbauer spectroscopy and conductivity.

  18. Shape-controlled solvothermal synthesis of bismuth subcarbonate nanomaterials

    SciTech Connect

    Cheng Gang; Yang Hanmin; Rong Kaifeng; Lu Zhong; Yu Xianglin; Chen Rong

    2010-08-15

    Much effort has been devoted to the synthesis of novel nanostructured materials because of their unique properties and potential applications. Bismuth subcarbonate ((BiO){sub 2}CO{sub 3}) is one of commonly used antibacterial agents against Helicobacter pylori (H. pylori). Different (BiO){sub 2}CO{sub 3} nanostructures such as cube-like nanoparticles, nanobars and nanoplates, were fabricated from bismuth nitrate via a simple solvothermal method. The nanostructures were characterized by powder X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM). It was found that the solvents and precursors have an influence on the morphologies of (BiO){sub 2}CO{sub 3} nanostructures. The possible formation mechanism of different (BiO){sub 2}CO{sub 3} nanostructures fabricated under different conditions was also discussed. - Graphical abstract: Different bismuth subcarbonate ((BiO){sub 2}CO{sub 3}) nanostructures were successfully synthesized by a simple solvothermal method. It was found that the solvents and precursors have an influence on the morphologies of (BiO){sub 2}CO{sub 3} nanostructures.

  19. Oxide layer stability in lead-bismuth at high temperature

    NASA Astrophysics Data System (ADS)

    Martín, F. J.; Soler, L.; Hernández, F.; Gómez-Briceño, D.

    2004-11-01

    Materials protection by 'in situ' oxidation has been studied in stagnant lead-bismuth, with different oxygen levels (H 2/H 2O ratios of 0.3 and 0.03), at temperatures from 535 °C to 600 °C and times from 100 to 3000 h. The materials tested were the martensitic steels F82Hmod, EM10 and T91 and the austenitic stainless steels, AISI 316L and AISI 304L. The results obtained point to the existence of an apparent threshold temperature above which corrosion occurs and the formation of a protective and stable oxide layer is not possible. This threshold temperature depends on material composition, oxygen concentration in the liquid lead-bismuth and time. The threshold temperature is higher for the austenitic steels, especially for the AISI 304L, and it increases with the oxygen concentration in the lead-bismuth. The oxide layer formed disappear with time and, after 3000 h all the materials, except AISI 304L, suffer corrosion, more severe for the martensitic steels and at the highest temperature tested.

  20. Atomic Layer Deposition of Bismuth Vanadates for Solar Energy Materials.

    PubMed

    Stefik, Morgan

    2016-07-01

    The fabrication of porous nanocomposites is key to the advancement of energy conversion and storage devices that interface with electrolytes. Bismuth vanadate, BiVO4 , is a promising oxide for solar water splitting where the controlled fabrication of BiVO4 layers within porous, conducting scaffolds has remained a challenge. Here, the atomic layer deposition of bismuth vanadates is reported from BiPh3 , vanadium(V) oxytriisopropoxide, and water. The resulting films have tunable stoichiometry and may be crystallized to form the photoactive scheelite structure of BiVO4 . A selective etching process was used with vanadium-rich depositions to enable the synthesis of phase-pure BiVO4 after spinodal decomposition. BiVO4 thin films were measured for photoelectrochemical performance under AM 1.5 illumination. The average photocurrents were 1.17 mA cm(-2) at 1.23 V versus the reversible hydrogen electrode using a hole-scavenging sulfite electrolyte. The capability to deposit conformal bismuth vanadates will enable a new generation of nanocomposite architectures for solar water splitting. PMID:27246652

  1. Thermodynamic properties of lanthanide metals in liquid bismuth

    NASA Astrophysics Data System (ADS)

    Yamana, Hajimu; Sheng, Jiawei; Souda, Naohiko; Moriyama, Hirotake

    2001-04-01

    Thermodynamic quantities of La, Gd, Tb, and Dy in liquid bismuth were experimentally determined by electromotive force (EMF) measurement using a cell consisting of molten alkaline chloride and liquid bismuth. Excess Gibbs energy changes and activity coefficients were determined at varying concentrations and temperatures. Through their temperature dependence, corresponding enthalpy changes and entropy changes were determined. The excess enthalpy changes of La, Gd, Tb, and Dy in liquid bismuth in a temperature range from 850 to 1100 K were evaluated to be, -221.54±2.31, -202.25±1.80, -199.83±0.55, and -193.80±0.99 kJ/mol, respectively. The systematic variation of excess enthalpy change of lanthanides along the 4f-series was discussed. As a result, it was found that the excess enthalpy changes of La, Gd, Tb, Dy, and Er are likely to depend linearly on the 2/3 power of their metallic volume.

  2. Bismuth pyrochlore-based thin films for dielectric energy storage

    NASA Astrophysics Data System (ADS)

    Michael, Elizabeth K.

    The drive towards the miniaturization of electronic devices has created a need for dielectric materials with large energy storage densities. These materials, which are used in capacitors, are a critical component in many electrical systems. Here, the development of dielectric energy storage materials for pulsed power applications, which require materials with the ability to accumulate a large amount of energy and then deliver it to the system rapidly, is explored. The amount of electrostatic energy that can be stored by a material is a function of the induced polarization and the dielectric breakdown strength of the material. An ideal energy storage dielectric would possess a high relative permittivity, high dielectric breakdown strength, and low loss tangent under high applied electric fields. The bismuth pyrochlores are a compositionally tunable family of materials that meet these requirements. Thin films of cubic pyrochlore bismuth zinc niobate, bismuth zinc tantalate, and bismuth zinc niobate tantalate, were fabricated using a novel solution chemistry based upon the Pechini method. This solution preparation is advantageous because it avoids the use of teratogenic solvents, such as 2-methoxyethanol. Crystalline films fabricated using this solution chemistry had very small grains that were approximately 27 nm in lateral size and 35 nm through the film thickness. Impedance measurements found that the resistivity of the grain boundaries was two orders of magnitude higher than the resistivity of the grain interior. The presence of many resistive grain boundaries impeded conduction through the films, resulting in high breakdown strengths for these materials. In addition to high breakdown strengths, this family of materials exhibited moderate relative permittivities of between 55 +/- 2 and 145 +/- 5, for bismuth zinc tantalate and bismuth zinc niobate, respectively, and low loss tangents on the order of 0.0008 +/- 0.0001. Increases in the concentration of the tantalum

  3. Airborne Laser Polar Nephelometer

    NASA Technical Reports Server (NTRS)

    Grams, Gerald W.

    1973-01-01

    A polar nephelometer has been developed at NCAR to measure the angular variation of the intensity of light scattered by air molecules and particles. The system has been designed for airborne measurements using outside air ducted through a 5-cm diameter airflow tube; the sample volume is that which is common to the intersection of a collimated source beam and the detector field of view within the airflow tube. The source is a linearly polarized helium-neon laser beam. The optical system defines a collimated field-of-view (0.5deg half-angle) through a series of diaphragms located behind a I72-mm focal length objective lens. A photomultiplier tube is located immediately behind an aperture in the focal plane of the objective lens. The laser beam is mechanically chopped (on-off) at a rate of 5 Hz; a two-channel pulse counter, synchronized to the laser output, measures the photomultiplier pulse rate with the light beam both on and off. The difference in these measured pulse rates is directly proportional to the intensity of the scattered light from the volume common to the intersection of the laser beam and the detector field-of-view. Measurements can be made at scattering angles from 15deg to 165deg with reference to the direction of propagation of the light beam. Intermediate angles are obtained by selecting the angular increments desired between these extreme angles (any multiple of 0.1deg can be selected for the angular increment; 5deg is used in normal operation). Pulses provided by digital circuits control a stepping motor which sequentially rotates the detector by pre-selected angular increments. The synchronous photon-counting system automatically begins measurement of the scattered-light intensity immediately after the rotation to a new angle has been completed. The instrument has been flown on the NASA Convair 990 airborne laboratory to obtain data on the complex index of refraction of atmospheric aerosols. A particle impaction device is operated simultaneously

  4. Bismuth Propellant Feed System Development at NASA-MSFC

    NASA Technical Reports Server (NTRS)

    Polzin, Kurt A.

    2007-01-01

    NASA-MSFC has been developing liquid metal propellant feed systems capable of delivering molten bismuth at a prescribed mass flow rate to the vaporizer of an electric thruster. The first such system was delivered to NASA-JPL as part of the Very High Isp Thruster with Anode Layer (VHITAL) program. In this system, the components pictured were placed in a vacuum chamber and heated while the control electronics were located outside the chamber. The system was successfully operated at JPL in conjunction with a propellant vaporizer, and data was obtained demonstrating a new liquid bismuth flow sensing technique developed at MSFC. The present effort is aimed at producing a feed-system for use in conjunction with a bismuth-fed Hall thruster developed by Busek Co. Developing this system is more ambitious, however, in that it is designed to self-contain all the control electronics inside the same vacuum chamber as an operating bismuth-fed thruster. Consequently, the entire system, including an on-board computer, DC-output power supplies, and a gas-pressurization electro-pneumatic regulator, must be designed to survive a vacuum environment and shielded to keep bismuth plasma from intruding on the electronics and causing a shortcircuit. In addition, the hot portions of the feed system must be thermally isolated from the electronics to avoid failure due to high heat loads. This is accomplished using a thermal protection system (TPS) consisting of multiple layers of aluminum foil. The only penetrations into the vacuum chamber are an electrically isolated (floating) 48 VDC line and a fiberoptic line. The 48 VDC provides power for operation of the power supplies and electronics co-located with the system in the vacuum chamber. The fiberoptic Ethernet connection is used to communicate user-input control commands to the on-board computer and transmit real-time data back to the external computer. The partially assembled second-generation system is shown. Before testing at Busek, a

  5. Unusual anti-thermal degradation of bismuth NIR luminescence in bismuth doped lithium tantalum silicate laser glasses.

    PubMed

    Tan, Linling; Wang, Liping; Peng, Mingying; Xu, Shanhui; Zhang, Qinyuan

    2016-08-01

    For application of bismuth laser glasses in either fiber amplifier or laser, their performance stability in long run should be understood especially in extreme conditions. However, so far, there are few reports on it. Here, we found, after the cycle experiments on heating and cooling, that the proper increase of lithium content in lithium tantalum silicate laser glass can lead to unusual anti-thermal degradation of bismuth NIR luminescence, which completely differs from the scenario in germanate glass. FTIR, 29Si MAS NMR spectra, absorption and dynamic photoluminescence spectra are employed to unravel how this happens. The results illustrate that it should be due to the decrease of polymerization of silicate glass network, which in turn allows the regeneration at 250°C, and therefore, the content increase of bismuth NIR emission centers. In the meanwhile, we noticed though Bi luminescence can be thermally quenched its peak does not shift along with temperature, which seldom appears in laser materials. The unique property might guarantee the unshift of Bi fiber laser wavelength once such glass was made into fiber devices even as the environmental temperature changes. The role of lithium is discussed in the evolution of glass structures, the suppression of glass heterogeneity, and the thermal stability of Bi luminescence, and it should be helpful to design homogeneous silicate laser glass with outstanding thermal stability. PMID:27505827

  6. Solvothermal synthesis and study of nonlinear optical properties of nanocrystalline thallium doped bismuth telluride

    SciTech Connect

    Molli, Muralikrishna; Parola, Sowmendran; Avinash Chunduri, L.A.; Aditha, Saikiran; Sai Muthukumar, V; Mimani Rattan, Tanu; Kamisetti, Venkataramaniah

    2012-05-15

    Nanocrystalline Bismuth telluride and thallium (4 mol %) doped Bismuth telluride were synthesized through hydrothermal method. The as-prepared products were characterized using Powder X-ray Diffraction, High Resolution Transmission Electron Microscopy, Energy Dispersive X-Ray Spectroscopy, UV-Visible spectroscopy and Fourier Transform Infrared Spectroscopy. Powder XRD results revealed the crystalline nature of the obtained phases. HRTEM showed the particle-like morphology of the products. The decrease in the absorption coefficient due to thallium doping was observed in FTIR spectra. The intensity dependent nonlinear optical properties of nanocrystalline bismuth telluride and thallium doped bismuth telluride were studied using the Z-scan technique in open-aperture configuration. Bismuth telluride doped with thallium showed enhanced nonlinear optical response compared to pristine bismuth telluride and hence could be used as a potential candidate for optical power limiting applications. - Graphical Abstract: Nonlinear transmission (Z-scan) curves of nanocrystalline bismuth telluride ({Delta}) and thallium doped bismuth telluride ({open_square}). Thallium doped bismuth telluride showed enhanced nonlinear absorption compared to bismuth telluride. Inset: TEM micrograph of bismuth telluride nanocrystallites. Highlights: Black-Right-Pointing-Pointer Synthesis of Nanocrystalline Bi{sub 2}Te{sub 3} and Thallium doped Bi{sub 2}Te{sub 3} through solvothermal method. Black-Right-Pointing-Pointer Reduced absorption coefficient due to thallium doping found from IR spectroscopy. Black-Right-Pointing-Pointer Open-aperture Z-scan technique for nonlinear optical studies. Black-Right-Pointing-Pointer Two photon absorption based model for theoretical fitting of Z-scan data. Black-Right-Pointing-Pointer Enhanced nonlinear absorption in Thallium doped Bi{sub 2}Te{sub 3} - potential candidate for optical power limiting applications.

  7. The accurate determination of bismuth in lead concentrates and other non-ferrous materials by AAS after separation and preconcentration of the bismuth with mercaptoacetic acid.

    PubMed

    Howell, D J; Dohnt, B R

    1982-05-01

    A method for determining 0.0001% and upwards of bismuth in lead, zinc or copper concentrates, metals or alloys and other smelter residues is described. Bismuth is separated from lead, iron and gangue materials with mercaptoacetic acid after reduction of the iron with hydrazine. Large quantities of tin can be removed during the dissolution. An additional separation is made for materials high in copper and/or sulphate. The separated and concentrated bismuth is determined by atomic-absorption spectrometry using the Bi line at 223.1 nm. The proposed method also allows the simultaneous separation and determination of silver. PMID:18963145

  8. An airborne isothermal haze chamber

    NASA Technical Reports Server (NTRS)

    Hindman, E. E.

    1981-01-01

    Thermal gradient diffusion cloud chambers (TGDCC) are used to determine the concentrations of cloud condensation nuclei (CCN) with critical supersaturations greater than or equal to about 0.2%. The CCN concentrations measured with the airborne IHC were lower than theoretically predicted by factors ranging between 7.9 and 9.0. The CCN concentrations measured with the airborne IHC were lower than the concentrations measured with the larger laboratory IHC's by factors ranging between 3.9 and 7.5. The bounds of the supersaturation ranges of the airborne IHC and the CSU-Mee TGDCC do not overlap. Nevertheless, the slopes of the interpolated data between the bounds agree favorably with the theoretical slopes.

  9. Airborne laser topographic mapping results

    NASA Technical Reports Server (NTRS)

    Krabill, W. B.; Collins, J. G.; Link, L. E.; Swift, R. N.; Butler, M. L.

    1984-01-01

    The results of terrain mapping experiments utilizing the National Aeronautics and Space Administration (NASA) Airborne Oceanographic Lidar (AOL) over forested areas are presented. The flight tests were conducted as part of a joint NASA/U.S. Army Corps of Engineers (CE) investigation aimed at evaluating the potential of an airborne laser ranging system to provide cross-sectional topographic data on flood plains that are difficult and expensive to survey using conventional techniques. The data described in this paper were obtained in the Wolf River Basin located near Memphis, TN. Results from surveys conducted under winter 'leaves off' and summer 'leaves on' conditions, aspects of day and night operation, and data obtained from decidous and coniferous tree types are compared. Data processing techniques are reviewed. Conclusions relative to accuracy and present limitations of the AOL, and airborne lidar systems in general, to terrain mapping over forested areas are discussed.

  10. WESTERN AIRBORNE CONTAMINANTS ASSESSMENT PROJECT RESEARCH PLAN

    EPA Science Inventory

    The goal of the Western Airborne Contaminants Assessment Project (WACAP) is to assess the deposition of airborne contaminants in Western National Parks, providing regional and local information on exposure, accumulation, impacts, and probable sources. This project is being desig...

  11. Airborne soil organic particles generated by precipitation

    NASA Astrophysics Data System (ADS)

    Wang, Bingbing; Harder, Tristan H.; Kelly, Stephen T.; Piens, Dominique S.; China, Swarup; Kovarik, Libor; Keiluweit, Marco; Arey, Bruce W.; Gilles, Mary K.; Laskin, Alexander

    2016-06-01

    Airborne organic particles play a critical role in Earth's climate, public health, air quality, and hydrological and carbon cycles. However, sources and formation mechanisms for semi-solid and solid organic particles are poorly understood and typically neglected in atmospheric models. Laboratory evidence suggests that fine particles can be formed from impaction of mineral surfaces by droplets. Here, we use chemical imaging of particles collected following rain events in the Southern Great Plains, Oklahoma, USA and after experimental irrigation to show that raindrop impaction of soils generates solid organic particles. We find that after rain events, sub-micrometre solid particles, with a chemical composition consistent with soil organic matter, contributed up to 60% of atmospheric particles. Our irrigation experiments indicate that intensive water impaction is sufficient to cause ejection of airborne soil organic particles from the soil surface. Chemical imaging and micro-spectroscopy analysis of particle physico-chemical properties suggest that these particles may have important impacts on cloud formation and efficiently absorb solar radiation. We suggest that raindrop-induced formation of solid organic particles from soils may be a widespread phenomenon in ecosystems such as agricultural systems and grasslands where soils are exposed to strong, episodic precipitation events.

  12. Auxiliary DCP data acquisition system. [airborne system

    NASA Technical Reports Server (NTRS)

    Snyder, R. V.

    1975-01-01

    An airborne DCP Data Aquisition System has been designed to augment the ERTS satellite data recovery system. The DCP's are data collection platforms located at pertinent sites. With the appropriate sensors they are able to collect, digitally encode and transmit environmental parameters to the ERTS satellite. The satellite in turn relays these transmissions to a ground station for processing. The satellite is available for such relay duty a minimum of two times in a 24-hour period. The equipment is to obtain continuous DCP data during periods of unusual environmental activity--storms, floods, etc. Two circumstances contributed to the decision to design such a system; (1) Wallops Station utilizes surveillance aircraft in support of rocket launches and also in support of earth resources activities; (2) the area in which Wallops is located, the Delaware and Chesapeake Bay areas, are fertile areas for DCP usage. Therefore, by developing an airborne DCP receiving station and installing it on aircraft more continuous DCP data can be provided from sites in the surrounding areas at relatively low cost.

  13. Structural, optical, and transport properties of nanocrystalline bismuth telluride thin films treated with homogeneous electron beam irradiation and thermal annealing.

    PubMed

    Takashiri, Masayuki; Asai, Yuki; Yamauchi, Kazuki

    2016-08-19

    We investigated the effects of homogeneous electron beam (EB) irradiation and thermal annealing treatments on the structural, optical, and transport properties of bismuth telluride thin films. Bismuth telluride thin films were prepared by an RF magnetron sputtering method at room temperature. After deposition, the films were treated with homogeneous EB irradiation, thermal annealing, or a combination of both the treatments (two-step treatment). We employed Williamson-Hall analysis for separating the strain contribution from the crystallite domain contribution in the x-ray diffraction data of the films. We found that strain was induced in the thin films by EB irradiation and was relieved by thermal annealing. The crystal orientation along c-axis was significantly enhanced by the two-step treatment. Scanning electron microscopy indicated the melting and aggregation of nano-sized grains on the film surface by the two-step treatment. Optical analysis indicated that the interband transition of all the thin films was possibly of the indirect type, and that thermal annealing and two-step treatment methods increased the band gap of the films due to relaxation of the strain. Thermoelectric performance was significantly improved by the two-step treatment. The power factor reached a value of 17.2 μW (cm(-1) K(-2)), approximately 10 times higher than that of the as-deposited thin films. We conclude that improving the crystal orientation and relaxing the strain resulted in enhanced thermoelectric performance. PMID:27389820

  14. Structural, optical, and transport properties of nanocrystalline bismuth telluride thin films treated with homogeneous electron beam irradiation and thermal annealing

    NASA Astrophysics Data System (ADS)

    Takashiri, Masayuki; Asai, Yuki; Yamauchi, Kazuki

    2016-08-01

    We investigated the effects of homogeneous electron beam (EB) irradiation and thermal annealing treatments on the structural, optical, and transport properties of bismuth telluride thin films. Bismuth telluride thin films were prepared by an RF magnetron sputtering method at room temperature. After deposition, the films were treated with homogeneous EB irradiation, thermal annealing, or a combination of both the treatments (two-step treatment). We employed Williamson–Hall analysis for separating the strain contribution from the crystallite domain contribution in the x-ray diffraction data of the films. We found that strain was induced in the thin films by EB irradiation and was relieved by thermal annealing. The crystal orientation along c-axis was significantly enhanced by the two-step treatment. Scanning electron microscopy indicated the melting and aggregation of nano-sized grains on the film surface by the two-step treatment. Optical analysis indicated that the interband transition of all the thin films was possibly of the indirect type, and that thermal annealing and two-step treatment methods increased the band gap of the films due to relaxation of the strain. Thermoelectric performance was significantly improved by the two-step treatment. The power factor reached a value of 17.2 μW (cm‑1 K‑2), approximately 10 times higher than that of the as-deposited thin films. We conclude that improving the crystal orientation and relaxing the strain resulted in enhanced thermoelectric performance.

  15. NASA Airborne Lidar 1982-1984 Flights

    Atmospheric Science Data Center

    2016-05-26

    NASA Airborne Lidar 1982-1984 Flights Data from the 1982 NASA Langley Airborne Lidar flights following the eruption of El Chichon ... continuing to January 1984. Transcribed from the following NASA Tech Reports: McCormick, M. P., and M. T. Osborn, Airborne lidar ...

  16. Method of Creating Micro-scale Silver Telluride Grains Covered with Bismuth Nanoparticles

    NASA Technical Reports Server (NTRS)

    Kim, Hyun-Jung (Inventor); Choi, Sang Hyouk (Inventor); King, Glen C. (Inventor); Park, Yeonjoon (Inventor); Lee, Kunik (Inventor)

    2014-01-01

    Provided is a method of enhancing thermoelectric performance by surrounding crystalline semiconductors with nanoparticles by contacting a bismuth telluride material with a silver salt under a substantially inert atmosphere and a temperature approximately near the silver salt decomposition temperature; and recovering a metallic bismuth decorated material comprising silver telluride crystal grains.

  17. Experimental investigation of forced-convection heat-transfer characteristics of lead-bismuth eutectic

    NASA Technical Reports Server (NTRS)

    Lubarsky, Bernard

    1951-01-01

    The forced-convection heat-transfer characteristics of lead-bismuth eutectic were experimentally investigated. Experimental values of Nusselt number for lead-bismuth fell considerably below predicted values. The addition of a wetting agent did not change the heat transfer characteristics.

  18. Physico-chemical characteristics of visibility impairment by airborne pollen in an urban area

    NASA Astrophysics Data System (ADS)

    Kim, Kyung W.

    The number of airborne pollen produced from plants is visible as a haze mixed with urban air pollution in an urban area when atmospheric conditions are proper for pollination of pollen from April to May in Korea. The big loading of airborne pollen can cause further visibility degradation in an urban area. In order to investigate physico-chemical characteristics of visibility impairment by airborne pollen, chemical aerosol measurements, optical aerosol monitoring, and scenic monitoring were performed during the intensive monitoring period from April 19 to May 2, 2005 in the urban area of Seoul, Korea. The particles collected on filters were examined with a scanning electron microscope (SEM) interfaced with an energy dispersive X-ray analysis to characterize size, elemental composition, and count of airborne pollen. During the airborne pollen period, the daily averaged number concentrations of airborne pollen; P and P were calculated to be 8.4±6.9 and 113.7±91.1 m -3, respectively. The daily averaged light extinction coefficient ( bext), light scattering coefficient for open path ( bscat), light scattering coefficient for dry particle in the fine regime ( bscat,fine), and light absorption coefficient in the fine regime ( babs,fine) were measured to be 459±267, 357±214, 263±165, and 44±30 Mm -1, respectively. And mass concentration of PM 2.5 and PM 10 were measured to be 46.5±29.1 and 97.0±41.7 μg m -3. The average light absorption coefficient by airborne pollen was estimated to be about 30 M m -1 and the average light scattering coefficient by airborne pollen was estimated to be 67±57 Mm -1. During the airborne pollen period the average contribution of airborne pollen to visibility impairment was roughly estimated to be 19-25%.

  19. Contribution of airborne dust particles to HONO sources

    NASA Astrophysics Data System (ADS)

    Saliba, N. A.; Moussa, S. G.; El Tayyar, G.

    2014-02-01

    HONO is a major precursor for OH radicals in early mornings. Its formation has been mainly attributed to the heterogeneous hydrolysis of NO2 on surfaces such as soot, glass, mineral oxides and aerosol surfaces. In particular, dust events which are loaded with mineral oxide aerosols have been associated with higher HONO concentrations in the gas phase. In order to understand the mechanism of reactions related to this process, samples during dusty and non-dusty days were collected between October 2009 and April 2011. Based on HYSPLIT backward trajectories, data were divided between wind trajectories originating from Arabian or African deserts. In this study an increase of HONO levels was observed during dusty days. The increase in the acidic gas concentrations was accompanied by an increase in the PM nitrate and sulfate ion concentrations. During high relative humidity (African dusty days), it is proposed that the mechanism of NO2 hydrolysis predominates whereas during Arabian dusty days, where the air is relatively dry, a synergistic mechanism of adsorption and reaction between NO2 and SO2 on dust particles to produce HONO and sulfate in the particle phase is suggested. This study implies that the NOx reactivity on mineral oxide surfaces leads to a higher mixing level of OH. An increase in the sulfate forming capacity could account for the underestimation of sulfates in aerosols when the reactive uptake of SO2 alone is considered.

  20. Bismuth-induced phase control of GaAs nanowires grown by molecular beam epitaxy

    SciTech Connect

    Lu, Zhenyu; Chen, Pingping E-mail: luwei@mail.sitp.ac.cn; Shi, Suixing; Yao, Luchi; Zhou, Xiaohao; Lu, Wei E-mail: luwei@mail.sitp.ac.cn; Zhang, Zhi; Zhou, Chen; Zou, Jin

    2014-10-20

    In this work, the crystal structure of GaAs nanowires grown by molecular beam epitaxy has been tailored only by bismuth without changing the growth temperature and V/III flux ratio. The introduction of bismuth can lead to the formation of zinc-blende GaAs nanowires, while the removal of bismuth changes the structure into a 4H polytypism before it turns back to the wurtzite phase eventually. The theoretical calculation shows that it is the steadiest for bismuth to adsorb on the GaAs(111){sub B} surface compared to the liquid gold catalyst surface and the interface between the gold catalyst droplet and the nanowire, and these adsorbed bismuth could decrease the diffusion length of adsorbed Ga and hence the supersaturation of Ga in the gold catalyst droplet.

  1. Optical properties of bismuth-doped silica fibres in the temperature range 300 - 1500 K

    SciTech Connect

    Dvoretskii, D A; Bufetov, Igor' A; Vel'miskin, V V; Zlenko, Alexander S; Khopin, V F; Semjonov, S L; Guryanov, Aleksei N; Denisov, L K; Dianov, Evgenii M

    2012-09-30

    The visible and near-IR absorption and luminescence bands of bismuth-doped silica and germanosilicate fibres have been measured for the first time as a function of temperature. The temperature-dependent IR luminescence lifetime of a bismuth-related active centre associated with silicon in the germanosilicate fibre has been determined. The Bi{sup 3+} profile across the silica fibre preform is shown to differ markedly from the distribution of IR-emitting bismuth centres associated with silicon. The present results strongly suggest that the IR-emitting bismuth centre comprises a lowvalence bismuth ion and an oxygen-deficient glass network defect. (optical fibres, lasers and amplifiers. properties and applications)

  2. Determination of nanogram amounts of bismuth in rocks by substoichiometric isotope dilution analysis

    USGS Publications Warehouse

    Greenland, L. Paul; Campbell, E.Y.

    1972-01-01

    A rapid procedure suitable for the routine determination of 1-10 ng of bismuth in a silicate rock matrix is described. Results for the U.S. Geological Survey standard rocks are presented. Rocks and minerals are dissolved in hydrofluoric-perchloric acid in the presence of 207Bi tracer and the silica is removed by evaporation. The perchloric acid residue is taken up in water and bismuth iodide is extracted into methyl isobutyl ketone. After three acid-iodide washes, the bismuth is stripped into water and reacted with a substoichiometric amount of EDTA. Excess of bismuth is extracted as the iodide and the specific activity of the bismuth-EDTA complex is determined. ?? 1972.

  3. CALIOPE and TAISIR airborne experiment platform

    SciTech Connect

    Chocol, C.J.

    1994-07-01

    Between 1950 and 1970, scientific ballooning achieved many new objectives and made a substantial contribution to understanding near-earth and space environments. In 1986, the Lawrence Livermore National Laboratory (LLNL) began development of ballooning technology capable of addressing issues associated with precision tracking of ballistic missiles. In 1993, the Radar Ocean Imaging Project identified the need for a low altitude (1 km) airborne platform for its Radar system. These two technologies and experience base have been merged with the acquisition of government surplus Aerostats by Lawrence Livermore National Laboratory. The CALIOPE and TAISIR Programs can benefit directly from this technology by using the Aerostat as an experiment platform for measurements of the spill facility at NTS.

  4. Fourth Airborne Geoscience Workshop: Summary Minutes

    NASA Technical Reports Server (NTRS)

    1991-01-01

    The general theme for the workshop revolved around global environmental change. Over 170 individuals participated in the presentations and ensuing discussions about the many agency activities using airborne platforms and sensors in support of the U.S. Global Change Research Program (GCRP). The U.S. GCRP was developed as a central component of the U.S. Government's approach to global change and its contribution to worldwide efforts. An all-encompassing U.S. plan was developed by the Committee on Earth and Environmental Sciences (CEES), which continues as the interagency coordinating group for the program. The U.S. GCRP was established as a Presidential initiative in the FY90 budget, making it a particularly relevant topic for the workshop. The following are presented in the appendices: (1) final agenda and list of registrants; (2) final list of poster presenters; (3) steering group luncheon participants; (4) the draft resolution; and (5) selected handouts.

  5. Airborne Imagery Collections Barrow 2013

    DOE Data Explorer

    Cherry, Jessica; Crowder, Kerri

    2015-07-20

    The data here are orthomosaics, digital surface models (DSMs), and individual frames captured during low altitude airborne flights in 2013 at the Barrow Environmental Observatory. The orthomosaics, thermal IR mosaics, and DSMs were generated from the individual frames using Structure from Motion techniques.

  6. Airborne fungi--a resurvey

    SciTech Connect

    Meyer, G.H.; Prince, H.E.; Raymer, W.J.

    1983-07-01

    A 15-month survey of airborne fungi at 14 geographical stations was conducted to determine the incidence of different fungal genera. Five of these stations were surveyed 25 years earlier. A comparison between previous studies and present surveys revealed similar organisms at each station with slight shifts in frequency of dominant genera.

  7. Tropospheric and Airborne Emission Spectrometers

    NASA Technical Reports Server (NTRS)

    Glavich, Thomas; Beer, Reinhard

    1996-01-01

    X This paper describes the development of two related instruments, the Tropospheric Emission Spectrometer (TES) and the Airborne Emission Spectrometer (AES). Both instruments are infrared imaging Fourier Transform Spectrometers, used for measuring the state of the lower atmosphere, and in particular the measurement of ozone and ozone sources and sinks.

  8. AARD - Autonomous Airborne Refueling Demonstration

    NASA Technical Reports Server (NTRS)

    Ewers, Dick

    2007-01-01

    This viewgraph document reviews the Autonomous Airborne Refueling Demonstration program, and NASA Dryden's work in the program. The primary goal of the program is to make one fully automatic probe-to-drogue engagement using the AARD system. There are pictures of the aircraft approaching to the docking.

  9. Airborne asbestos in public buildings

    SciTech Connect

    Chesson, J.; Hatfield, J.; Schultz, B.; Dutrow, E.; Blake, J. )

    1990-02-01

    The U.S. Environmental Protection Agency sampled air in 49 government-owned buildings (six buildings with no asbestos-containing material, six buildings with asbestos-containing material in generally good condition, and 37 buildings with damaged asbestos-containing material). This is the most comprehensive study to date of airborne asbestos levels in U.S. public buildings during normal building activities. The air outside each building was also sampled. Air samples were analyzed by transmission electron microscopy using a direct transfer preparation technique. The results show an increasing trend in average airborne asbestos levels; outdoor levels are lowest and levels in buildings with damaged asbestos-containing material are highest. However, the measured levels and the differences between indoors and outdoors and between building categories are small in absolute magnitude. Comparable studies from Canada and the UK, although differing in their estimated concentrations, also conclude that while airborne asbestos levels may be elevated in buildings that contain asbestos, levels are generally low. This conclusion does not eliminate the possibility of higher airborne asbestos levels during maintenance or renovation that disturbs the asbestos-containing material.

  10. Cytotoxic Effect of Lipophilic Bismuth Dimercaptopropanol Nanoparticles on Epithelial Cells.

    PubMed

    Rene, Hernandez-Delgadillo; Badireddy, Appala Raju; José, Martínez-Sanmiguel Juan; Francisco, Contreras-Cordero Juan; Israel, Martinez-Gonzalez Gustavo; Isela, Sánchez-Nájera Rosa; Chellam, Shankararaman; Claudio, Cabral-Romero

    2016-01-01

    Bismuth nanoparticles have many interesting properties to be applied in biomedical and medicinal sectors, however their safety in humans have not been comprehensively investigated. The objective of this research was to determine the cytotoxic effect of bismuth dimercaptopropanol nanoparticles (BisBAL NPs) on epithelial cells. The nanoparticles are composed of 18.7 nm crystallites on average and have a rhombohedral structure, agglomerating into chains-like or clusters of small nanoparticles. Based on MTT viability assay and fluorescence microscopy, cytotoxicity was not observed on monkey kidney cells after growing with 5 µM of BisBAL NPs for 24 h. Employing same techniques, identical results were obtained with human epithelial cells (HeLa), showing a not strain-dependent phenomenon. The absence of toxic effects on epithelial cells growing with BisBAL NPs was corroborated with long-time experiments (24-72 hrs.), showing no difference in comparison with growing control (cells without nanoparticles). Further, genotoxicity assays, comet assay and fluorescent microscopy and electrophoresis in bromide-stained agarose gel revealed no damage to genomic DNA of MA104 cells after 24 h. of exposition to BisBAL NPs. Finally, the effect of bismuth nanoparticles on protein synthesis was studied in cells growing with BisBAL NPs for 24 h. SDS-PAGE assays showed no difference between treated and untreated cells, suggesting that BisBAL NPs did not interfere with protein synthesis. Hence BisBAL NPs do not appear to exert cytotoxic effects suggesting their biological compatibility with epithelial cells. PMID:27398446

  11. Bismuth oxide nanotubes-graphene fiber-based flexible supercapacitors

    NASA Astrophysics Data System (ADS)

    Gopalsamy, Karthikeyan; Xu, Zhen; Zheng, Bingna; Huang, Tieqi; Kou, Liang; Zhao, Xiaoli; Gao, Chao

    2014-07-01

    Graphene-bismuth oxide nanotube fiber as electrode material for constituting flexible supercapacitors using a PVA/H3PO4 gel electrolyte is reported with a high specific capacitance (Ca) of 69.3 mF cm-2 (for a single electrode) and 17.3 mF cm-2 (for the whole device) at 0.1 mA cm-2, respectively. Our approach opens the door to metal oxide-graphene hybrid fibers and high-performance flexible electronics.Graphene-bismuth oxide nanotube fiber as electrode material for constituting flexible supercapacitors using a PVA/H3PO4 gel electrolyte is reported with a high specific capacitance (Ca) of 69.3 mF cm-2 (for a single electrode) and 17.3 mF cm-2 (for the whole device) at 0.1 mA cm-2, respectively. Our approach opens the door to metal oxide-graphene hybrid fibers and high-performance flexible electronics. Electronic supplementary information (ESI) available: Equations and characterization. SEM images of GGO, XRD and XPS of Bi2O3 NTs, HRTEM images and EDX Spectra of Bi2O3 NT5-GF, CV curves of Bi2O3NT5-GF, Bi2O3 NTs and bismuth nitrate in three-electrode system (vs. Ag/AgCl). CV and GCD curves of Bi2O3 NT1-GF and Bi2O3 NT3-GF. See DOI: 10.1039/c4nr02615b

  12. Hydrothermal synthesis of sodium bismuth titanate and titanate nanofibers

    NASA Astrophysics Data System (ADS)

    Kundu, Animesh

    A hydrothermal processing method was developed for the synthesis of sodium bismuth titanate powders and thin films from suitable precursors at 150°C. Oxide precursors were best suited for preparing pure phase materials. The sodium bismuth titanate powders consisted of cube shaped crystals. A modified solution-reprecitation model involving partial dissolution of the precursors was proposed to explain the growth of these particles. The thin films were prepared on strontium titanate (100) substrate. A sample holder was specially designed and fabricated to secure the substrates in the reaction vessel. The result was a relatively smooth film of thickness ≤550 nm. The films were essentially single crystalline and had strong epitaxial relationship with the substrate. Titanate nanofibers (NaxH yTinO2n+1° zH2O) were known to form under similar hydrothermal conditions as sodium bismuth titanate powders. Detail research revealed that the pure hydroxide and oxide precursors tend to form sodium bismuth titanate powders or thin films. Titanate nanofibers were the predominant product when any other ions or organics were present in the precursor. Much faster reaction kinetics for the formation of nanofibers was observed when certain organic compounds were added deliberately with the precursors. Accordingly, a hydrothermal process was developed for converting the precursors to titanate nanofibers in a significantly shorter time than reported in the literature. A thin film consisting of vertically aligned nanofibers was prepared on titanium substrate at 150°C in as little as 30 minutes. Complete conversion of starting precursors to free standing nanofibers was achieved in ˜8 hours at 150°C. The as-prepared nanofibers were some form of sodium titanate. They were converted to hydrogen titanate by ion exchange. Differential Scanning calorimetric experiments were performed to understand the thermal evolution of the fibers. The hydrogen titanate fibers underwent structural

  13. Kinetics of Propagating Phase Transformation in Compressed Bismuth

    SciTech Connect

    Bastea, M; Bastea, S; Emig, J; Springer, P; Reisman, D

    2004-08-18

    The authors observed dynamically driven phase transitions in isentropically compressed bismuth. By changing the stress loading conditions they explored two distinct cases one in which the experimental signature of the phase transformation corresponds to phase-boundary crossings initiated at both sample interfaces, and another in which the experimental trace is due to a single advancing transformation front in the bulk of the material. They introduce a coupled kinetics-hydrodynamics model that for this second case enables them, under suitable simplifying assumptions, to directly extract characteristic transition times from the experimental measurements.

  14. Lattice dynamics study of bismuth III V compounds

    NASA Astrophysics Data System (ADS)

    Belabbes, A.; Zaoui, A.; Ferhat, M.

    2008-10-01

    We present first-principles calculations of the structural and lattice-dynamical properties for cubic bismuth III-V compounds: BBi, AlBi and GaBi. The ground-state properties, i.e., the lattice constant and the bulk modulus, are calculated using a plane wave pseudopotential method within density functional theory. A linear-response approach to density functional theory is used to derive the phonon frequencies. The effect of pressure on the dynamical charges and the longitudinal optical-transverse optical splitting is also examined.

  15. Growth and Characterization of Bismuth and Antimony Thin Films

    NASA Astrophysics Data System (ADS)

    Martinez, A.; Berrios, A. R.; Collazo, R.; Garcia, J. L.; Ducoudray, G. O.

    1996-03-01

    We have grown thin films of bismuth and antimony using hot wall epitaxy. The polycrystalline films were grown onto (111)-silicon substrates. The chemical integrity of the films was established using Auger electron spectroscopy. The crystallographical properties of the films were assessed using x-ray diffraction techniques. We will report on the results of these characterization efforts, as well as, on the growth apparatus and process. Work supported in part by NSWC-CRADA 93-01 and EPSCoR-NSF Grant EHR-9108775

  16. Ultrafast carrier dynamics in polycrystalline bismuth telluride nanofilm

    SciTech Connect

    Jia, Lin; Ma, Weigang; Zhang, Xing

    2014-06-16

    In this study, the dynamics of energy carriers in polycrystalline bismuth telluride nanofilm are investigated by the ultrafast pump-probe method. The energy relaxation processes are quantitatively analyzed by using the numerical fitting models. The extracted hot carrier relaxation times of photon excitation, thermalization, and diffusion are around sub-picosecond. The initial reflectivity recovery is found to be dominantly determined by the carrier diffusion, electron-phonon coupling, and photo-generated carriers trapping processes. High-frequency and low-frequency oscillations are both observed and attributed to coherent optical phonons and coherent acoustic phonons, respectively.

  17. Thermoelectric and structural characterizations of individual electrodeposited bismuth telluride nanowires

    NASA Astrophysics Data System (ADS)

    Mavrokefalos, Anastassios; Moore, Arden L.; Pettes, Michael T.; Shi, Li; Wang, Wei; Li, Xiaoguang

    2009-05-01

    The thermoelectric properties and crystal structure of individual electrodeposited bismuth telluride nanowires (NWs) were characterized using a microfabricated measurement device and transmission electron microscopy. Annealing in hydrogen was used to obtain electrical contact between the NW and the supporting Pt electrodes. By fitting the measured Seebeck coefficient with a two-band model, the NW samples were determined to be highly n-type doped. Higher thermal conductivity and electrical conductivity were observed in a 52 nm diameter monocrystalline NW than a 55 nm diameter polycrystalline NW. The electron mobility of the monocrystalline NW was found to be about 19% lower than that of bulk crystal at a similar carrier concentration and about 2.5 times higher than that of the polycrystalline NW. The specularity parameter for electron scattering by the NW surface was determined to be about 0.7 and partially specular and partially diffuse, leading to a reduction in the electron mean-free path from 61 nm in the bulk to about 40 nm in the 52 nm NW. Because of the already short phonon mean-free path of about 3 nm in bulk bismuth telluride, diffuse phonon-surface scattering is expected to reduce the lattice thermal conductivity of the 52-55 nm diameter NWs by only about 20%, which is smaller than the uncertainty in the extracted lattice thermal conductivity based on the measured total thermal conductivity and calculated electron thermal conductivity. Although the lattice thermal conductivity of the polycrystalline NW is likely lower than the bulk values, the lower thermal conductivity observed in this polycrystalline sample is mainly caused by the lower electron concentration and mobility. For both samples, the thermoelectric figure of merit (ZT) increases with temperature and is about 0.1 at a temperature of 400 K. The low ZT compared to that of bulk crystals is mainly caused by a high doping level, suggesting the need for better control of the chemical composition in

  18. Satellite and airborne IR sensor validation by an airborne interferometer

    SciTech Connect

    Gumley, L.E.; Delst, P.F. van; Moeller, C.C.

    1996-11-01

    The validation of in-orbit longwave IR radiances from the GOES-8 Sounder and inflight longwave IR radiances from the MODIS Airborne Simulator (MAS) is described. The reference used is the airborne University of Wisconsin High Resolution Interferometer Sounder (HIS). The calibration of each sensor is described. Data collected during the Ocean Temperature Interferometric Survey (OTIS) experiment in January 1995 is used in the comparison between sensors. Detailed forward calculations of at-sensor radiance are used to account for the difference in GOES-8 and HIS altitude and viewing geometry. MAS radiances and spectrally averaged HIS radiances are compared directly. Differences between GOES-8 and HIS brightness temperatures, and GOES-8 and MAS brightness temperatures, are found to be with 1.0 K for the majority of longwave channels examined. The same validation approach will be used for future sensors such as the Moderate Resolution Imaging Spectroradiometer (MODIS) and the Atmospheric Infrared Sounder (AIRS). 11 refs., 2 figs., 4 tabs.

  19. Solvothermal synthesis of uniform bismuth nanospheres using poly(N-vinyl-2-pyrrolidone) as a reducing agent

    PubMed Central

    2011-01-01

    Uniform bismuth nanospheres were successfully prepared from bismuth nitrate in the presence of poly(N-vinyl-2-pyrrolidone) (PVP) by solvothermal process. The product was characterized by powder X-ray diffraction, scanning electron microscopy, transmission electron microscopy, selected area electron diffraction, and energy-dispersive X-ray. PVP plays a critical role both as a reducing agent and a capping agent in the formation of bismuth nanospheres. Shape and size of bismuth nanospheres could be tuned by changing the employed PVP/bismuth salt ratio. It was also found the solvent had an effect on the morphologies of bismuth nanomaterials. The possible formation and growth mechanism of bismuth nanospheres were also discussed and proposed to explain the reduction step. PMID:21711606

  20. Dielectric investigations on co-substituted bismuth ferrite (Bi1-xLaxFe1-xMnxO3)

    NASA Astrophysics Data System (ADS)

    Kumar, Sunil; Supriya, Sweety; Kumar, Pawan; Kar, Manoranjan

    2016-05-01

    Bi1-xLaxFe1-xMnxO3 ceramics with x=0.00, 0.05, 0.10 and 0.20 were synthesized by the tartaric acid modified sol-gel technique with required optimization. The co-substitution suppresses the impurities phases in bismuth ferrite which is usually observed. It was observed that the composition-driven structural transition from rhombohedral (R3c space group) to orthorhombic symmetry (Pbnm space group) plays an important role in modifying the dielectric properties of bismuth ferrite. The dielectric constant was found to be increased in La and Mn co-substituted BiFeO3 due to significant large off-center movement of Fe3+ ions in the oxygen octahedra. The dispersion of dielectric constant in the frequency range of 100 Hz to 1 MHz has been analyzed by employing the modified Debye's function which suggests the contribution of multiple charge carriers in the dielectric relaxation.

  1. Structural and electronic properties of III-V bismuth compounds

    NASA Astrophysics Data System (ADS)

    Ferhat, M.; Zaoui, A.

    2006-03-01

    We have performed ab initio self-consistent calculations based on the full potential linear augmented plane-wave method with the generalized gradient approximation to investigate the structural and the electronic properties of the less known bismuth III-V compounds: BBi, AlBi, GaBi, and InBi. Ground state parameters are computed and compared with available theoretical and experimental works. The zinc-blende phase is found to be the most stable for BBi, AlBi, and GaBi, while InBi prefers the tetragonal PbO structure. The relativistic contraction of the 6s orbital of Bi has strong effect on the band structure of III-Bi compounds, which exhibits some features that differ considerably from those of typical III-V semiconductors. In particular, we found an inverted band gap, which reflects a semimetallic character of these systems. Their bonding nature is analyzed in terms of valence charge density transfer, showing three different natures of the bond. Besides, the calculated valence charge density for BBi shows an anomalous behavior characterized by a charge transfer toward the cation B atom, while the others III-Bi behave as the typical III-V compounds with a small charge transfer to the anion bismuth atom.

  2. Superconductivity in Bismuth. A New Look at an Old Problem

    PubMed Central

    2016-01-01

    To investigate the relationship between atomic topology, vibrational and electronic properties and superconductivity of bismuth, a 216-atom amorphous structure (a-Bi216) was computer-generated using our undermelt-quench approach. Its pair distribution function compares well with experiment. The calculated electronic and vibrational densities of states (eDOS and vDOS, respectively) show that the amorphous eDOS is about 4 times the crystalline at the Fermi energy, whereas for the vDOS the energy range of the amorphous is roughly the same as the crystalline but the shapes are quite different. A simple BCS estimate of the possible crystalline superconducting transition temperature gives an upper limit of 1.3 mK. The e-ph coupling is more preponderant in a-Bi than in crystalline bismuth (x-Bi) as indicated by the λ obtained via McMillan’s formula, λc = 0.24 and experiment λa = 2.46. Therefore with respect to x-Bi, superconductivity in a-Bi is enhanced by the higher values of λ and of eDOS at the Fermi energy. PMID:26815431

  3. Electronic band structure calculations of bismuth-antimony nanowires

    NASA Astrophysics Data System (ADS)

    Levin, Andrei; Dresselhaus, Mildred

    2012-02-01

    Alloys of bismuth and antimony received initial interest due to their unmatched low-temperature thermoelectric performance, and have drawn more recent attention as the first 3D topological insulators. One-dimensional bismuth-antimony (BiSb) nanowires display interesting quantum confinement effects, and are expected to exhibit even better thermoelectric properties than bulk BiSb. Due to the small, anisotropic carrier effective masses, the electronic properties of BiSb nanowires show great sensitivity to nanowire diameter, crystalline orientation, and alloy composition. We develop a theoretical model for calculating the band structure of BiSb nanowires. For a given crystalline orientation, BiSb nanowires can be in the semimetallic, direct semiconducting, or indirect semiconducting phase, depending on nanowire diameter and alloy composition. These ``phase diagrams'' turn out to be remarkably similar among the different orientations, which is surprising in light of the anisotropy of the bulk BiSb Fermi surface. We predict a novel direct semiconducting phase for nanowires with diameter less than ˜15 nm, over a narrow composition range. We also find that, in contrast to the bulk and thin film BiSb cases, a gapless state with Dirac dispersion cannot be realized in BiSb nanowires.

  4. New Bismuth-Substituted Hydroxyapatite Nanoparticles for Bone Tissue Engineering

    NASA Astrophysics Data System (ADS)

    Ciobanu, Gabriela; Bargan, Ana Maria; Luca, Constantin

    2015-11-01

    New bismuth-substituted hydroxyapatite [Ca10- x Bi x (PO4)6(OH)2 where x = 0-2.5] nanoparticles were synthesized by the co-precipitation method from aqueous solutions. The structural properties of the samples were analyzed by scanning electron microscopy coupled with x-ray analysis, x-ray powder diffraction, x-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy and Brunauer-Emmett-Teller surface area analysis. The results confirm that bismuth ions have been incorporated into the hydroxyapatite lattice. The prepared nanocrystalline powders consisted of hydroxyapatite as single phase with hexagonal structure, crystal sizes smaller than 60 nm and (Bi + Ca)/P atomic ratio of around 1.67. The hydroxyapatite samples doped with Bi have mesoporous textures with pores size of around 2 nm and specific surface area in the range of 12-25 m2/g. The Bi-substituted hydroxyapatite powders are more effective against Gram-negative Escherichia coli bacteria than Gram-positive Staphylococcus aureus bacteria.

  5. Superconductivity in Bismuth. A New Look at an Old Problem.

    PubMed

    Mata-Pinzón, Zaahel; Valladares, Ariel A; Valladares, Renela M; Valladares, Alexander

    2016-01-01

    To investigate the relationship between atomic topology, vibrational and electronic properties and superconductivity of bismuth, a 216-atom amorphous structure (a-Bi216) was computer-generated using our undermelt-quench approach. Its pair distribution function compares well with experiment. The calculated electronic and vibrational densities of states (eDOS and vDOS, respectively) show that the amorphous eDOS is about 4 times the crystalline at the Fermi energy, whereas for the vDOS the energy range of the amorphous is roughly the same as the crystalline but the shapes are quite different. A simple BCS estimate of the possible crystalline superconducting transition temperature gives an upper limit of 1.3 mK. The e-ph coupling is more preponderant in a-Bi than in crystalline bismuth (x-Bi) as indicated by the λ obtained via McMillan's formula, λc = 0.24 and experiment λa = 2.46. Therefore with respect to x-Bi, superconductivity in a-Bi is enhanced by the higher values of λ and of eDOS at the Fermi energy. PMID:26815431

  6. Radiopacity in bone cements using an organo-bismuth compound.

    PubMed

    Deb, S; Abdulghani, S; Behiri, J C

    2002-08-01

    In a joint replacement surgery it is vital for bone cement to be radiologically detectable. Consequently, heavy metal salts of barium and zirconia are incorporated as a contrast medium for this purpose. The addition of such particulate additives, however, can be detrimental to some of the physical, mechanical and biological properties. The present study reports the feasibility of using an organo-bismuth compound, namely. triphenyl bismuth (TPB) as a radiopaque agent for orthopaedic bone cements. TPB was incorporated in the bone cement matrix by two methods, (i) blending: TPB was added to the polymer phase of the bone cement and (ii) dissolution: by dissolving TPB in the monomer phase methylmethacrylate. The results showed that the inclusion of TPB at concentrations of 15% and 25% by weight of the polymer, in the bone cement matrix did not affect the polymerisation exotherm temperature and setting time. Furthermore, the addition of TPB via the dissolution method provided a statistically significant increase in the strain to failure in comparison to commercial acrylic cements containing barium sulphate, thus reducing the brittleness of the cement. The detrimental effects on the mechanical properties post conditioning in water, was also much less pronounced in the homogeneous TPB cements in comparison to barium sulphate containing cements. These observations can be attributed to the formation of a homogeneous and continuous matrix of the resultant bone cement with a much lower porosity. PMID:12099281

  7. Angle Dependence of the Orbital Magnetoresistance in Bismuth

    NASA Astrophysics Data System (ADS)

    Collaudin, Aurélie; Fauqué, Benoît; Fuseya, Yuki; Kang, Woun; Behnia, Kamran

    2015-04-01

    We present an extensive study of angle-dependent transverse magnetoresistance in bismuth, with a magnetic field perpendicular to the applied electric current and rotating in three distinct crystallographic planes. The observed angular oscillations are confronted with the expectations of semiclassic transport theory for a multivalley system with anisotropic mobility and the agreement allows us to quantify the components of the mobility tensor for both electrons and holes. A quadratic temperature dependence is resolved. As Hartman argued long ago, this indicates that inelastic resistivity in bismuth is dominated by carrier-carrier scattering. At low temperature and high magnetic field, the threefold symmetry of the lattice is suddenly lost. Specifically, a 2 π /3 rotation of magnetic field around the trigonal axis modifies the amplitude of the magnetoresistance below a field-dependent temperature. By following the evolution of this anomaly as a function of temperature and magnetic field, we map the boundary in the (field, temperature) plane separating two electronic states. In the less symmetric state, confined to low temperature and high magnetic field, the three Dirac valleys cease to be rotationally invariant. We discuss the possible origins of this spontaneous valley polarization, including a valley-nematic scenario.

  8. Layered bismuth oxyhalide nanomaterials for highly efficient tumor photodynamic therapy

    NASA Astrophysics Data System (ADS)

    Xu, Yu; Shi, Zhenzhi; Zhang, Ling'e.; Brown, Eric Michael Bratsolias; Wu, Aiguo

    2016-06-01

    Layered bismuth oxyhalide nanomaterials have received much more interest as promising photocatalysts because of their unique layered structures and high photocatalytic performance, which can be used as potential inorganic photosensitizers in tumor photodynamic therapy (PDT). In recent years, photocatalytic materials have been widely used in PDT and photothermal therapy (PTT) as inorganic photosensitizers. This investigation focuses on applying layered bismuth oxyhalide nanomaterials toward cancer PDT, an application that has never been reported so far. The results of our study indicate that the efficiency of UV-triggered PDT was highest when using BiOCl nanoplates followed by BiOCl nanosheets, and then TiO2. Of particular interest is the fact that layered BiOCl nanomaterials showed excellent PDT effects under low nanomaterial dose (20 μg mL-1) and low UV dose (2.2 mW cm-2 for 10 min) conditions, while TiO2 showed almost no therapeutic effect under the same parameters. BiOCl nanoplates and nanosheets have shown excellent performance and an extensive range of applications in PDT.

  9. Layered bismuth oxyhalide nanomaterials for highly efficient tumor photodynamic therapy.

    PubMed

    Xu, Yu; Shi, Zhenzhi; Zhang, Ling'e; Brown, Eric Michael Bratsolias; Wu, Aiguo

    2016-07-01

    Layered bismuth oxyhalide nanomaterials have received much more interest as promising photocatalysts because of their unique layered structures and high photocatalytic performance, which can be used as potential inorganic photosensitizers in tumor photodynamic therapy (PDT). In recent years, photocatalytic materials have been widely used in PDT and photothermal therapy (PTT) as inorganic photosensitizers. This investigation focuses on applying layered bismuth oxyhalide nanomaterials toward cancer PDT, an application that has never been reported so far. The results of our study indicate that the efficiency of UV-triggered PDT was highest when using BiOCl nanoplates followed by BiOCl nanosheets, and then TiO2. Of particular interest is the fact that layered BiOCl nanomaterials showed excellent PDT effects under low nanomaterial dose (20 μg mL(-1)) and low UV dose (2.2 mW cm(-2) for 10 min) conditions, while TiO2 showed almost no therapeutic effect under the same parameters. BiOCl nanoplates and nanosheets have shown excellent performance and an extensive range of applications in PDT. PMID:26287933

  10. Effect of O-vacancies on magnetic properties of bismuth ferrite nanoparticles by solution evaporation method

    NASA Astrophysics Data System (ADS)

    Afzal, A. M.; Umair, M.; Dastgeer, G.; Rizwan, M.; Yaqoob, M. Z.; Rashid, R.; Munir, H. S.

    2016-02-01

    Bismuth ferrite is a multiferroic material which shows high magnetization and polarization at room temperature. In present work, the effect of Oxygen (O) vacancies on magnetic properties of bismuth ferrite nanoparticles is studied. Bismuth ferrite nanoparticles (BiFeO3) were synthesized by solution evaporation method (SEM) at room temperature. The sample was annealed under two different atmospheres such as in air and oxygen, to check the effect of O-vacancies on magnetic properties. The average crystallite size of Bismuth ferrite nanoparticles (NPs) as calculated by X-ray diffraction (XRD) falls in the range of 23-32 nm and 26-39 nm for the case of air and oxygen respectively. The crystallite size of bismuth ferrite nanoparticles increases as the temperature was varied from 450 °C to 650 °C. Further the influence of annealing temperature on the magnetic properties of the bismuth ferrite nanoparticles was also observed. It was concluded that the magnetic properties of Bismuth ferrite nanoparticles are directly interconnected to annealing atmosphere and annealing temperature. The magnetic properties were increased in the case of oxygen annealing, which actually leads in our case to an improvement of the crystallinity.

  11. Bismuth oxide aqueous colloidal nanoparticles inhibit Candida albicans growth and biofilm formation

    PubMed Central

    Hernandez-Delgadillo, Rene; Velasco-Arias, Donaji; Martinez-Sanmiguel, Juan Jose; Diaz, David; Zumeta-Dube, Inti; Arevalo-Niño, Katiushka; Cabral-Romero, Claudio

    2013-01-01

    Multiresistance among microorganisms to common antimicrobials has become one of the most significant concerns in modern medicine. Nanomaterials are a new alternative to successfully treat the multiresistant microorganisms. Nanostructured materials are used in many fields, including biological sciences and medicine. Recently, it was demonstrated that the bactericidal activity of zero-valent bismuth colloidal nanoparticles inhibited the growth of Streptococcus mutans; however the antimycotic potential of bismuth nanostructured derivatives has not yet been studied. The main objective of this investigation was to analyze the fungicidal activity of bismuth oxide nanoparticles against Candida albicans, and their antibiofilm capabilities. Our results showed that aqueous colloidal bismuth oxide nanoparticles displayed antimicrobial activity against C. albicans growth (reducing colony size by 85%) and a complete inhibition of biofilm formation. These results are better than those obtained with chlorhexidine, nystatin, and terbinafine, the most effective oral antiseptic and commercial antifungal agents. In this work, we also compared the antimycotic activities of bulk bismuth oxide and bismuth nitrate, the precursor metallic salt. These results suggest that bismuth oxide colloidal nanoparticles could be a very interesting candidate as a fungicidal agent to be incorporated into an oral antiseptic. Additionally, we determined the minimum inhibitory concentration for the synthesized aqueous colloidal Bi2O3 nanoparticles. PMID:23637533

  12. Elemental characterization of the airborne pollen surface using Electron Probe Microanalysis (EPMA)

    NASA Astrophysics Data System (ADS)

    Duque, Laura; Guimarães, Fernanda; Ribeiro, Helena; Sousa, Raquel; Abreu, Ilda

    2013-08-01

    Recent worldwide increase in pollinoses has been attributed to the synergy between pollen and pollutants. We used EPMA for the elemental characterization of the airborne pollen surface in order to find out what occurs to the wall of pollen grains when they are together with other atmospheric pollutants. Analyses were performed both to airborne pollen and to pollen that was collected from Acer spp., Platanus spp. and Pinus spp. trees. Airborne samples were assembled using a Hirst-type volumetric spore sampler set in the coastal city of Porto, Portugal. Airborne pollen samples showed major elemental differences when compared to the control pollen sample of the same species, namely in the amounts of Cl, Na and Mg, which very significantly increased on airborne samples, revealing an important influence of the ocean. Mineral dust also contributed to modify the pollen surface, by increasing Si contents on Acer spp. and Platanus spp. airborne pollen. Our results revealed consistent positive effects of the relative humidity and the precipitation in the increase of Cl, Na and Mg relative amounts on the pollen surface. This study shows that pollen grains have the ability to adsorb and/or absorb other materials, which may contribute to enhance pollen's harmful effects on people's health.

  13. Large aperture scanning airborne lidar

    NASA Technical Reports Server (NTRS)

    Smith, J.; Bindschadler, R.; Boers, R.; Bufton, J. L.; Clem, D.; Garvin, J.; Melfi, S. H.

    1988-01-01

    A large aperture scanning airborne lidar facility is being developed to provide important new capabilities for airborne lidar sensor systems. The proposed scanning mechanism allows for a large aperture telescope (25 in. diameter) in front of an elliptical flat (25 x 36 in.) turning mirror positioned at a 45 degree angle with respect to the telescope optical axis. The lidar scanning capability will provide opportunities for acquiring new data sets for atmospheric, earth resources, and oceans communities. This completed facility will also make available the opportunity to acquire simulated EOS lidar data on a near global basis. The design and construction of this unique scanning mechanism presents exciting technological challenges of maintaining the turning mirror optical flatness during scanning while exposed to extreme temperatures, ambient pressures, aircraft vibrations, etc.

  14. Magnetic airborne survey - geophysical flight

    NASA Astrophysics Data System (ADS)

    de Barros Camara, Erick; Nei Pereira Guimarães, Suze

    2016-06-01

    This paper provides a technical review process in the area of airborne acquisition of geophysical data, with emphasis for magnetometry. In summary, it addresses the calibration processes of geophysical equipment as well as the aircraft to minimize possible errors in measurements. The corrections used in data processing and filtering are demonstrated with the same results as well as the evolution of these techniques in Brazil and worldwide.

  15. Airborne microorganisms from waste containers.

    PubMed

    Jedlicka, Sabrina S; Stravitz, David M; Lyman, Charles E

    2012-01-01

    In physician's offices and biomedical labs, biological waste is handled every day. This waste is disposed of in waste containers designed for holding red autoclave bags. The containers used in these environments are closed hands-free containers, often with a step pedal. While these containers protect the user from surface-borne microorganisms, the containers may allow airborne microorganisms to escape via the open/close mechanism because of the air current produced upon open/close cycles. In this study, the air current was shown to be sufficient to allow airborne escape of microorganisms held in the container, including Aspergillus niger. However, bacterial cultures, such as Escherichia coli and Lactococcus lactis did not escape. This may be due to the choice of bacterial cultures and the absence of solid waste, such as dust or other particulate matter in the waste containers, that such strains of bacteria could travel on during aerosolization. We compared these results to those obtained using a re-designed receptacle, which mimimizes air currents, and detected no escaping microorganisms. This study highlights one potential source of airborne contamination in labs, hospitals, and other environments that dispose of biological waste. PMID:23047084

  16. Airborne lidar global positioning investigations

    NASA Technical Reports Server (NTRS)

    Krabill, W. B.

    1988-01-01

    The Global Positioning System (GPS) network of satellites shows high promise of revolutionizing methods for conducting surveying, navigation, and positioning. This is especially true in the case of airborne or satellite positioning. A single GPS receiver (suitably adapted for aircraft deployment) can yield positioning accuracies (world-wide) in the order of 30 to 50 m vertically, as well as horizontally. This accuracy is dramatically improved when a second GPS receiver is positioned at a known horizontal and vertical reference. Absolute horizontal and vertical positioning of 1 to 2 m are easily achieved over areas of separation of tens of km. If four common satellites remain in lock in both receivers, then differential phase pseudo-ranges on the GPS L-band carrier can be utilized to achieve accuracies of + or - 10 cm and perhaps as good as + or - 2 cm. The initial proof of concept investigation for airborne positioning using the phase difference between the airborne and stationary GPS receivers was conducted and is examined.

  17. NASA Student Airborne Research Program

    NASA Astrophysics Data System (ADS)

    Schaller, E. L.; Shetter, R. E.

    2012-12-01

    The NASA Student Airborne Research Program (SARP) is a unique summer internship program for advanced undergraduates and early graduate students majoring in the STEM disciplines. SARP participants acquire hands-on research experience in all aspects of an airborne research campaign, including flying onboard an major NASA resource used for studying Earth system processes. In summer 2012, thirty-two participants worked in four interdisciplinary teams to study surface, atmospheric, and oceanographic processes. Participants assisted in the operation of instruments onboard the NASA P-3B aircraft where they sampled and measured atmospheric gases and imaged land and water surfaces in multiple spectral bands. Along with airborne data collection, students participated in taking measurements at field sites. Mission faculty and research mentors helped to guide participants through instrument operation, sample analysis, and data reduction. Over the eight-week program, each student developed an individual research project from the data collected and delivered a conference-style final presentation on his/her results. We will discuss the results and effectiveness of the program from the first four summers and discuss plans for the future.

  18. Airborne particulate matter in spacecraft

    NASA Technical Reports Server (NTRS)

    1988-01-01

    Acceptability limits and sampling and monitoring strategies for airborne particles in spacecraft were considered. Based on instances of eye and respiratory tract irritation reported by Shuttle flight crews, the following acceptability limits for airborne particles were recommended: for flights of 1 week or less duration (1 mg/cu m for particles less than 10 microns in aerodynamic diameter (AD) plus 1 mg/cu m for particles 10 to 100 microns in AD); and for flights greater than 1 week and up to 6 months in duration (0.2 mg/cu m for particles less than 10 microns in AD plus 0.2 mg/cu m for particles 10 to 100 microns in AD. These numerical limits were recommended to aid in spacecraft atmosphere design which should aim at particulate levels that are a low as reasonably achievable. Sampling of spacecraft atmospheres for particles should include size-fractionated samples of 0 to 10, 10 to 100, and greater than 100 micron particles for mass concentration measurement and elementary chemical analysis by nondestructive analysis techniques. Morphological and chemical analyses of single particles should also be made to aid in identifying airborne particulate sources. Air cleaning systems based on inertial collection principles and fine particle collection devices based on electrostatic precipitation and filtration should be considered for incorporation into spacecraft air circulation systems. It was also recommended that research be carried out in space in the areas of health effects and particle characterization.

  19. Measurement of partial L fluorescence yields of bismuth using synchrotron radiation.

    PubMed

    Ménesguen, Yves; Boyer, Bruno; Rodrigues, Matias; Lépy, Marie-Christine

    2016-03-01

    Tunable monochromatic photon radiation was used to measure transmission of a bismuth target in the energy range from 7keV to 20keV. Partial L fluorescence yields of bismuth were obtained by combining measurement of the fluorescence induced by photoionization of the bismuth target and X-rays from the radioactive decay of (210)Pb. Several photon energies have been used to successively ionize the L subshells, which allowed detailed analysis of the rearrangement spectra and determination of the X-ray relative intensities of the L1, L2 and L3 series. PMID:26651165

  20. Increased InAs quantum dot size and density using bismuth as a surfactant

    SciTech Connect

    Dasika, Vaishno D.; Krivoy, E. M.; Nair, H. P.; Maddox, S. J.; Park, K. W.; Yu, E. T.; Bank, S. R.; Jung, D.; Lee, M. L.

    2014-12-22

    We have investigated the growth of self-assembled InAs quantum dots using bismuth as a surfactant to control the dot size and density. We find that the bismuth surfactant increases the quantum dot density, size, and uniformity, enabling the extension of the emission wavelength with increasing InAs deposition without a concomitant reduction in dot density. We show that these effects are due to bismuth acting as a reactive surfactant to kinetically suppress the surface adatom mobility. This mechanism for controlling quantum dot density and size has the potential to extend the operating wavelength and enhance the performance of various optoelectronic devices.

  1. Exploiting Chemistry to Improve Performance of Screen-Printed, Bismuth Film Electrodes (SP-BiFE).

    PubMed

    Dossi, Carlo; Monticelli, Damiano; Pozzi, Andrea; Recchia, Sandro

    2016-01-01

    Mercury substitution is a big issue in electroanalysis, and the search for a suitable, and less toxic, replacement is still under development. Of all the proposed alternatives, bismuth films appear to be the most viable solution, although they are still suffering some drawbacks, particularly the influence of deposition conditions and linearity at low concentrations. In this paper, the most promising strategies for bismuth film deposition on screen-printed electrodes (surface modifications, polymeric film deposition, insoluble salt precursors) will be evaluated for trace metal analysis. Particular attention will be devoted to bismuth chemistry, aiming to rationalize their electroanalytic performance. PMID:27455338

  2. PRODUCTION OF PLUTONIUM FLUORIDE FROM BISMUTH PHOSPHATE PRECIPITATE CONTAINING PLUTONIUM VALUES

    DOEpatents

    Brown, H.S.; Bohlmann, E.G.

    1961-05-01

    A process is given for separating plutonium from fission products present on a bismuth phosphate carrier. The dried carrier is first treated with hydrogen fluoride at between 500 and 600 deg C whereby some fission product fluorides volatilize away from plutonium tetrafluoride, and nonvolatile fission product fluorides are formed then with anhydrous fluorine at between 400 and 500 deg C. Bismuth and plutonium distill in the form of volatile fluorides away from the nonvolatile fission product fluorides. The bismuth and plutonium fluorides are condensed at below 290 deg C.

  3. Oxidation mechanism of formic acid on the bismuth adatom-modified Pt(111) surface.

    PubMed

    Perales-Rondón, Juan Victor; Ferre-Vilaplana, Adolfo; Feliu, Juan M; Herrero, Enrique

    2014-09-24

    In order to improve catalytic processes, elucidation of reaction mechanisms is essential. Here, supported by a combination of experimental and computational results, the oxidation mechanism of formic acid on Pt(111) electrodes modified by the incorporation of bismuth adatoms is revealed. In the proposed model, formic acid is first physisorbed on bismuth and then deprotonated and chemisorbed in formate form, also on bismuth, from which configuration the C-H bond is cleaved, on a neighbor Pt site, yielding CO2. It was found computationally that the activation energy for the C-H bond cleavage step is negligible, which was also verified experimentally. PMID:25188779

  4. Structural and optical characterization of thermally evaporated bismuth and antimony films for photovoltaic applications

    NASA Astrophysics Data System (ADS)

    Srimathy, N.; Ruban Kumar, A.

    2016-05-01

    In this present study, the thin film of bismuth and antimony is coated by thermal evaporation system equipped with the inbuilt ultra high vacuum system. XRD analysis confirmed the rhombohedral structure of Bismuth and Antimony on the prepared film. The surface roughness and physical appearance is analyzed by Atomic force microscopy. The results of Raman Spectroscopy show the wave functions and the spectrum of electrons. The preparation technique and conditions strongly influence the crystalline structure and the phase composition of bismuth and antimony thin films. The electrical and optical properties for the prepared film are analyzed. The results show a great interest and promising applications in Photovoltaic devices.

  5. Determination of nanogram amounts of bismuth in rocks by atomic absorption spectrometry with electrothermal atomization

    USGS Publications Warehouse

    Kane, J.S.

    1979-01-01

    Bismuth concentrations as low as 10 ng g-1 in 100-mg samples of geological materials can be determined by atomic absorption spectrometry with electrothermal atomization. After HF-HClO4 decomposition of the sample, bismuth is extracted as the iodide into methyl isobutyl ketone and is then stripped with ethylenediaminetetraacetic acid into the aqueous phase. Aliquots of this solution are pipetted into the graphite furnace and dried, charred, and atomized in an automated sequence. Atomic absorbance at the Bi 223.1-nm line provides a measure of the amount of bismuth present. Results are presented for 14 U.S. Geological Survey standard rocks. ?? 1979.

  6. Bismuth nano-droplets for group-V based molecular-beam droplet epitaxy

    NASA Astrophysics Data System (ADS)

    Li, C.; Zeng, Z. Q.; Fan, D. S.; Hirono, Y.; Wu, J.; Morgan, T. A.; Hu, X.; Yu, S. Q.; Wang, Zh. M.; Salamo, G. J.

    2011-12-01

    Self-assembly of bismuth droplets at nanoscale on GaAs(100) surface using molecular beam epitaxy was demonstrated. Fine control of density and size was achieved by varying growth temperature and total bismuth deposition. Droplet density was tuned by roughly 3 orders of magnitude, and the density-temperature dependence was found to be consistent with classical nucleation theory. These results may extend the flexibility of droplet epitaxy by serving as templates for group V based droplet epitaxy, which is in contrast to conventional group III based droplet epitaxy and may encourage nanostructure formation of bismuth-containing materials.

  7. Anti-Stokes luminescence in bismuth-doped silica and germania-based fibers.

    PubMed

    Firstov, Sergei V; Khopin, Vladimir F; Velmiskin, Vladimir V; Firstova, Elena G; Bufetov, Igor A; Guryanov, Alexei N; Dianov, Evgeny M

    2013-07-29

    Luminescence excitation spectra of active centers in bismuth-doped vitreous SiO(2) and vitreous GeO(2) optical fibers under the two-step excitation have been obtained for the first time. The results revealed only one bismuth-related IR active center formed in each of these fibers. The observed IR luminescence bands at 1430 nm (1650 nm) and 830 nm (950 nm), yellow-orange (red) band at 580 nm (655 nm), violet (blue) band at 420 nm (480 nm) belong to this bismuth-related active center in the vitreous SiO(2) (vitreous GeO(2)), correspondingly. PMID:23938712

  8. Sources of airborne microorganisms in the built environment.

    PubMed

    Prussin, Aaron J; Marr, Linsey C

    2015-01-01

    Each day people are exposed to millions of bioaerosols, including whole microorganisms, which can have both beneficial and detrimental effects. The next chapter in understanding the airborne microbiome of the built environment is characterizing the various sources of airborne microorganisms and the relative contribution of each. We have identified the following eight major categories of sources of airborne bacteria, viruses, and fungi in the built environment: humans; pets; plants; plumbing systems; heating, ventilation, and air-conditioning systems; mold; dust resuspension; and the outdoor environment. Certain species are associated with certain sources, but the full potential of source characterization and source apportionment has not yet been realized. Ideally, future studies will quantify detailed emission rates of microorganisms from each source and will identify the relative contribution of each source to the indoor air microbiome. This information could then be used to probe fundamental relationships between specific sources and human health, to design interventions to improve building health and human health, or even to provide evidence for forensic investigations. PMID:26694197

  9. Survival rate of airborne Mycobacterium bovis.

    PubMed

    Gannon, B W; Hayes, C M; Roe, J M

    2007-04-01

    Despite years of study the principle transmission route of bovine tuberculosis to cattle remains unresolved. The distribution of pathological lesions, which are concentrated in the respiratory system, and the very low dose of Mycobacterium bovis needed to initiate infection from a respiratory tract challenge suggest that the disease is spread by airborne transmission. Critical to the airborne transmission of a pathogenic microorganism is its ability to survive the stresses incurred whilst airborne. This study demonstrates that M. bovis is resistant to the stresses imposed immediately after becoming airborne, 94% surviving the first 10 min after aerosolisation. Once airborne the organism is robust, its viability decreasing with a half-life of approximately 1.5 hours. These findings support the hypothesis that airborne transmission is the principle route of infection for bovine tuberculosis. PMID:17045316

  10. Airborne Trailblazer: Two decades with NASA Langley's 737 flying laboratory

    NASA Technical Reports Server (NTRS)

    Wallace, Lane E.

    1994-01-01

    This book is the story of a very unique aircraft and the contributions it has made to the air transportation industry. NASA's Boeing 737-100 Transport Systems Research Vehicle started life as the prototype for Boeing's 737 series of aircraft. The airplane was acquired by LaRC in 1974 to conduct research into advanced transport aircraft technologies. In the twenty years that followed, the airplane participated in more than twenty different research projects, evolving from a research tool for a specific NASA program into a national airborne research facility. It played a critical role in developing and gaining acceptance for numerous significant transport technologies including 'glass cockpits,' airborne windshear detection systems, data links for air traffic control communications, the microwave landing system, and the satellite-based global positioning system (GPS).

  11. An update on the NAST-I airborne FTS

    NASA Astrophysics Data System (ADS)

    Larar, Allen M.; Smith, William L.; Zhou, Daniel K.; Liu, Xu; Noe, Anna; Oliver, Don; Flood, Michael; Rochette, Luc; Tian, Jialin

    2011-11-01

    The NPOESS / NASA Airborne Sounder Testbed - Interferometer (NAST-I) is a well-proven airborne remote sensing system, which has flown in 18 previous field campaigns aboard the high altitude NASA ER-2, Northrop Grumman / Scaled Composites Proteus, and NASA WB-57 aircraft since initially being flight qualified in 1998. While originally developed to provide experimental observations needed to finalize specifications and test proposed designs and data processing algorithms for the Cross-track Infrared Sounder (CrIS) to fly on the National Polar-orbiting Operational Environmental Satellite System (NPOESS) Preparatory Project (NPP) and the Joint Polar Satellite System, JPSS (formerly NPOESS, prior to recent program restructuring), its unprecedented data quality and system characteristics have contributed to a variety of atmospheric research and measurement validation objectives. This paper will provide a program overview and update, including a summary of measurement system capabilities, select scientific results, and recent refurbishment activities.

  12. Heat capacity, enthalpy and entropy of ternary bismuth tantalum oxides

    SciTech Connect

    Leitner, J.; Jakes, V.; Sofer, Z.; Sedmidubsky, D.; Ruzicka, K.; Svoboda, P.

    2011-02-15

    Heat capacity and enthalpy increments of ternary bismuth tantalum oxides Bi{sub 4}Ta{sub 2}O{sub 11}, Bi{sub 7}Ta{sub 3}O{sub 18} and Bi{sub 3}TaO{sub 7} were measured by the relaxation time method (2-280 K), DSC (265-353 K) and drop calorimetry (622-1322 K). Temperature dependencies of the molar heat capacity in the form C{sub pm}=445.8+0.005451T-7.489x10{sup 6}/T{sup 2} J K{sup -1} mol{sup -1}, C{sub pm}=699.0+0.05276T-9.956x10{sup 6}/T{sup 2} J K{sup -1} mol{sup -1} and C{sub pm}=251.6+0.06705T-3.237x10{sup 6}/T{sup 2} J K{sup -1} mol{sup -1} for Bi{sub 3}TaO{sub 7}, Bi{sub 4}Ta{sub 2}O{sub 11} and for Bi{sub 7}Ta{sub 3}O{sub 18}, respectively, were derived by the least-squares method from the experimental data. The molar entropies at 298.15 K, S{sup o}{sub m}(298.15 K)=449.6{+-}2.3 J K{sup -1} mol{sup -1} for Bi{sub 4}Ta{sub 2}O{sub 11}, S{sup o}{sub m}(298.15 K)=743.0{+-}3.8 J K{sup -1} mol{sup -1} for Bi{sub 7}Ta{sub 3}O{sub 18} and S{sup o}{sub m}(298.15 K)=304.3{+-}1.6 J K{sup -1} mol{sup -1} for Bi{sub 3}TaO{sub 7}, were evaluated from the low-temperature heat capacity measurements. -- Graphical Abstract: Temperature dependence of {Delta}{sub ox}C{sub pm} for bismuth tantalum mixed oxides. Display Omitted Research highlights: > Heat capacity, enthalpy and entropy of ternary bismuth tantalum oxides Bi{sub 4}Ta{sub 2}O{sub 11}, Bi{sub 7}Ta{sub 3}O{sub 18} and Bi{sub 3}TaO{sub 7}. > Heat capacity by DSC calorimetry and heat-pulsed calorimetry. > Enthalpy increments by drop calorimetry. > Einstein-Debye model for low-temperature dependence of the heat capacity. > Application of Neumann-Kopp rule.

  13. Multi-center Airborne Coherent Atmospheric Wind Sensor (MACAWS)

    NASA Astrophysics Data System (ADS)

    Rhothermel, Jeffry; Jones, W. D.; Dunkin, J. A.; McCaul, E. W., Jr.

    1993-01-01

    This effort involves development of a calibrated, pulsed coherent CO2 Doppler lidar, followed by a carefully-planned and -executed program of multi-dimensional wind velocity and aerosol backscatter measurements from the NASA DC-8 research aircraft. The lidar, designated as the Multi-center Airborne Coherent Atmospheric Wind Sensor (MACAWS), will be applicable to two research areas. First, MACAWS will enable specialized measurements of atmospheric dynamical processes in the planetary boundary layer and free troposphere in geographic locations and over scales of motion not routinely or easily accessible to conventional sensors. The proposed observations will contribute fundamentally to a greater understanding of the role of the mesoscale, helping to improve predictive capabilities for mesoscale phenomena and to provide insights into improving model parameterizations of sub-grid scale processes within large-scale circulation models. As such, it has the potential to contribute uniquely to major, multi-institutional field programs planned for the mid 1990's. Second, MACAWS measurements can be used to reduce the degree of uncertainty in performance assessments and algorithm development for NASA's prospective Laser Atmospheric Wind Sounder (LAWS), which has no space-based instrument heritage. Ground-based lidar measurements alone are insufficient to address all of the key issues. To minimize costs, MACAWS is being developed cooperatively by the lidar remote sensing groups of the Jet Propulsion Laboratory, NOAA Wave Propagation Laboratory, and MSFC using existing lidar hardware and manpower resources. Several lidar components have already been exercised in previous airborne lidar programs (for example, MSFC Airborne Doppler Lidar System (ADLS) used in 1981,4 Severe Storms Wind Measurement Program; JPL Airborne Backscatter Lidar Experiment (ABLE) used in 1989,90 Global Backscatter Experiment Survey Missions). MSFC has been given responsibility for directing the overall

  14. Facile synthesis and shape control of bismuth nanoflowers induced by surfactants

    NASA Astrophysics Data System (ADS)

    Dai, Yunrong; Song, Yonghui

    2014-01-01

    Several nano-sized bismuth materials with different shapes were fabricated using ionic/nonionic surfactant as a synthesis agent. Ionic surfactants brought about the formation of irregular nanoparticles while nonionic surfactants directed the synthesis of uniform hexagonal nanoprisms. Among them, the nonionic surfactant Pluronic P123 (poly(ethyleneoxide)-poly(propyleneoxide)-poly(ethyleneoxide), PEO20PPO70PEO20) could act as the reductant/shape-directing bifunctional agent for successfully reducing Bi3+ to Bi0 and inducing many hexagonal nanoprisms to grow from one crystal seed and finally form the graceful bismuth nanoflowers. The molding mechanism of bismuth nanoflowers might be attributed to the accommodation, stabilization and induction effects of P123 micelles for bismuth crystal seeds.

  15. Corrosion by liquid lead and lead-bismuth: experimental results review and analysis

    SciTech Connect

    Zhang, Jinsuo

    2008-01-01

    Liquid metal technologies for liquid lead and lead-bismuth alloy are under wide investigation and development for advanced nuclear energy systems and waste transmutation systems. Material corrosion is one of the main issues studied a lot recently in the development of the liquid metal technology. This study reviews corrosion by liquid lead and lead bismuth, including the corrosion mechanisms, corrosion inhibitor and the formation of the protective oxide layer. The available experimental data are analyzed by using a corrosion model in which the oxidation and scale removal are coupled. Based on the model, long-term behaviors of steels in liquid lead and lead-bismuth are predictable. This report provides information for the selection of structural materials for typical nuclear reactor coolant systems when selecting liquid lead or lead bismuth as heat transfer media.

  16. Spectral behaviour of bismuth centres in different steps of the FCVD process

    SciTech Connect

    Zlenko, Alexander S; Mashinsky, Valerii M; Iskhakova, L D; Ermakov, R P; Semjonov, S L; Koltashev, V V

    2013-07-31

    The behaviour of bismuth ions in silica glass free of other dopants has been studied in different steps of the furnace chemical vapour deposition (FCVD) process. Porous layers annealed and consolidated in different atmospheres, a bismuth chloride solution in acetone for porous layer impregnation, the resultant glass preform and holey fibres drawn out under various conditions have been characterised by spectroscopic techniques and X-ray diffraction. Active bismuth centres present in the preform and luminescing in the visible and IR spectral regions persist during drawing under reducing conditions, whereas drawing under oxidising conditions eliminates such centres. Annealing under reducing conditions produces absorption bands of IR-emitting bismuth centres (IRBCs) in spectra of fibres drawn out under oxidising conditions and concurrently increases the background loss. Under the annealing conditions of this study (argon atmosphere, T{sub max} = 1100 Degree-Sign C, 30 min), the IRBC concentration reaches a maximum and then decreases, whereas the background loss increases monotonically. (fiber optics)

  17. METHOD FOR RECOVERING PLUTONIUM VALUES FROM SOLUTION USING A BISMUTH HYDROXIDE CARRIER PRECIPITATE

    DOEpatents

    Faris, B.F.

    1961-04-25

    Carrier precipitation processes for separating plutonium values from aqueous solutions are described. In accordance with the invention a bismuth hydroxide precipitate is formed in the plutonium-containing solution, thereby carrying plutonium values from the solution.

  18. Low temperature synthesis of bismuth ferrite nanoparticles by a ferrioxalate precursor method

    SciTech Connect

    Ghosh, Sushmita; Dasgupta, Subrata . E-mail: sdasgupta@cgcri.res.in; Sen, Amarnath; Maiti, Himadri Sekhar

    2005-12-08

    The synthesis of bismuth ferrite by solid-state reaction of Bi{sub 2}O{sub 3} and Fe{sub 2}O{sub 3} results in the formation of multiphase products. Even coprecipitation followed by calcination leads to the formation of impurity phases. Here, we report the synthesis of magnetoelectric bismuth ferrite by a ferrioxalate precursor method. In this process, bismuth ferrite, synthesized through solutions of some specific salts led to the formation of phase pure (perovskite) nanocrystalline powder (11-22 nm as evident from X-ray diffraction analysis) at a temperature of 600 deg. C. The synthesized powders were characterized by X-ray diffractometry, thermogravimetry and differential thermal analysis, Fourier transformation infrared spectroscopy and scanning electron microscopy. The synthesis route is simple, energy saving and cost-effective. Such nanosized bismuth ferrite powder may have a potential application in making lead free piezoelectric materials for actuators as well as magnetoelectric sensors.

  19. Development of Large Bismuth Absorbers for Magnetic Calorimeters Applied to Hard X-ray Spectrometry

    NASA Astrophysics Data System (ADS)

    Rodrigues, M.; Loidl, M.; Pies, C.; Fleischmann, A.; Enss, C.

    2014-08-01

    Bismuth is an interesting material for magnetic calorimeter absorbers applied to high energy resolution X-ray spectrometry; it has a low specific heat and high atomic number. However, past detector developments with Bi absorbers were confronted with the low thermal conductivity of bismuth that degraded the energy resolution and deformed the detector response function (non-Gaussian energy peak). In the present study, we have investigated the performances of large bulk bismuth absorbers ( mm) thermally coupled to metallic magnetic sensors. Despite a very good baseline energy resolution, detectors with monolithic bismuth absorbers have degraded FWHM energy resolutions with any type of thermal coupling between the absorber and the sensor tested. In comparison tests with BiCu and BiAg bilayer absorbers demonstrated much better performances.

  20. The experience in handling of lead-bismuth coolant contaminated by Polonium-210

    SciTech Connect

    Pankratov, D.V.; Gromov, B.F.; Solodjankin, M.A.

    1993-12-31

    During exploitation of lead-bismuth cooled reactors a wide experience in handling of radioactive coolant containing polonium has been gained. By 1990 total time of this reactor operation has reached approximately 60 reactor years.

  1. Compatibility of structural materials with liquid bismuth, lead, and mercury

    SciTech Connect

    Weeks, J.R.

    1996-06-01

    During the 1950s and 1960s, a substantial program existed at Brookhaven National Laboratory as part of the Liquid Metal Fuel reactor program on the compatibility of bismuth, lead, and their alloys with structural materials. Subsequently, compatibility investigations of mercury with structural materials were performed in support of development of Rankine cycle mercury turbines for nuclear applications. The present talk will review present understanding of the corrosion/mass-transfer reactions of structural materials with these liquid metal coolants. Topics to be discussed include the basic solubility relationships of iron, chromium, nickel, and refractory metals in these liquid metals, the results of inhibition studies, the role of oxygen on the corrosion processes, and specialized topics such as cavitation-corrosion and liquid metal embrittlement. Emphasis will be placed on utilizing the understanding gained in this earlier work on the development of heavy liquid metal targets in spallation neutron sources.

  2. Oxygen concentration measurement in liquid lead-bismuth eutectic

    SciTech Connect

    Darling, T. W.; Li, N.

    2001-01-01

    Liquid lead-bismuth (Pb-Bi) eutectic (LBE) may see extensive use as a coolant fluid, and perhaps also as a spallation target, in next generation nuclear energy systems. While it is not as reactive as alkali metal liquids, it does present a long term corrosion problem with some materials, notably stainless steels. Mitigation of the corrosion problem may be achieved by producing and maintaining a protective oxide on exposed surfaces, through control of the concentration of dissolved oxygen in the LBE. We have developed an oxygen sensor based on available zirconia-based solid electrolytes used in the automotive industry, which represents a relatively inexpensive source of reproducible and reliable components. We will present the design considerations and characteristics of our sensor unit, and describe its use in the LBE test loop at Los Alamos for measurement and control of dissolved oxygen concentration.

  3. Solubility of gallium arsenide in bismuth-gallium melts

    SciTech Connect

    Yakusheva, N.A.; Chikichev, S.I.

    1988-03-01

    The solubility of GaAs in melts of the system Bi-Ga at 700, 800, and 850/degree/C was determined. For all isotherms of the liquids the existence of a maximum for a Bi concentration in the solvent of approx. 85 at. % and a maximum in the case of a bismuth concentration of approx. 10 at. % are characteristic. The experimental data do not agree with calculations based on the model of regularly associated solutions. For the quasibinary system Bi-GaAs the solubility of As in the interval 600-900/degree/C is described by the expression C/sub As/ = 1.1 /times/ 10/sup /minus/5/ /times/ exp (9.45 /times/ 10/sup /minus/3/ /times/ t) atomic fractions.

  4. Evaporation of mercury impurity from liquid lead-bismuth eutectic

    NASA Astrophysics Data System (ADS)

    Aerts, A.; Danaci, S.; Gonzalez Prieto, B.; Van den Bosch, J.; Neuhausen, J.

    2014-05-01

    The equilibrium evaporation of mercury from dilute solutions in liquid lead-bismuth eutectic (LBE) was studied in argon atmosphere. Mercury present as impurity in LBE was evaporated and detected by atomic fluorescence spectroscopy. A method which could accurately simulate the experimental data was developed. Coefficients of the Henry constant temperature correlation for mercury dissolved in LBE were determined. Experiments with samples from several different batches of LBE revealed that mercury at mole fractions between 10-6 and 10-12 and temperatures between 150 and 350 °C evaporated from liquid LBE close to ideal behavior. Evaporation of mercury from solid LBE on the other hand was unexpectedly high. These results are important for safety evaluations of LBE based spallation targets and accelerator driven systems.

  5. Photoelastic constants of germanate glasses containing lead and bismuth oxides

    SciTech Connect

    Rabukhin, A.I.

    1995-07-01

    Regression equations which accurately approximate the concentration curves of the photoelastic constants of lead bismuth germanate glasses were obtained and the isolines of the photoelastic constants were plotted and graphically illustrate the change in the properties of the glasses in almost the entire glass-formation region of the PbO-Bi{sub 2}O{sub 3}-GeO{sub 2} system. The partial values of the photoelastic constants of the oxides, components of these glasses, were determined and are in agreement with the values established for glasses of other systems. The data obtained can be used in planning the compositions of effective optical media for fabrication of light and acoustic lines for acousto-optic instruments and glasses with a zero optical stress coefficient.

  6. Investigation of the dielectric properties of bismuth pyrochlores

    NASA Astrophysics Data System (ADS)

    Cann, David P.; Randall, Clive A.; Shrout, Thomas R.

    1996-11-01

    The dielectric properties of polycrystalline bismuth-based pyrochlores of the general chemical form Bi 2(B {2}/{3}2+B {4}/{3}5+)O 7 and Bi 2(B 3+B 5+)O 7 where B 2+ = Mg, Cu, Zn and Ni, B 3+ = Sc and In, and B 5+ = Nb and Ta, were investigated as a function of temperature and frequency. At low temperatures ( T ˜ 100-150 K), a dielectric dispersion was universally observed within these systems. The dielectric dispersion was analyzed using phenomenological models often used for describing dipolar glass systems. Similar activation energies and pre-exponential damping frequencies are found to exist with dipolar glasses such as RADP (Rb xH 2PO 4(NH 4) 1- xH 2PO 4), K 1- xLi xTaO 3, KBr 1- xCN x and KI 1- x(NO 2) x.

  7. High thermoelectric performance of the distorted bismuth(110) layer.

    PubMed

    Cheng, L; Liu, H J; Zhang, J; Wei, J; Liang, J H; Jiang, P H; Fan, D D; Sun, L; Shi, J

    2016-07-14

    The thermoelectric properties of the distorted bismuth(110) layer are investigated using first-principles calculations combined with the Boltzmann transport equation for both electrons and phonons. To accurately predict the electronic and transport properties, the quasiparticle corrections with the GW approximation of many-body effects have been explicitly included. It is found that a maximum ZT value of 6.4 can be achieved for n-type systems, which essentially stemmed from the weak scattering of electrons. Moreover, we demonstrate that the distorted Bi layer retains high ZT values in relatively broad regions of both temperature and carrier concentration. Our theoretical work emphasizes that the deformation potential constant characterizing the electron-phonon scattering strength is an important paradigm for searching high thermoelectric performance materials. PMID:27302907

  8. Bismuth-doped Mg - Al silicate glasses and fibres

    SciTech Connect

    Bufetov, Igor' A; Vel'miskin, V V; Galagan, B I; Denker, B I; Sverchkov, S E; Semjonov, S L; Firstov, Sergei V; Shulman, I L; Dianov, Evgenii M

    2012-09-30

    This paper compares the optical properties of bulk bismuth-doped Mg - Al silicate glasses prepared in an iridium crucible to those of optical fibres prepared by the powder-in-tube method and having a core identical in composition to the glasses. The bulk glasses and fibres are shown to be similar in luminescence properties. The optical loss in the fibres in their IR luminescence band is about one order of magnitude lower than that in the crucible-melted glasses. The level of losses in the fibres and their luminescence properties suggest that such fibres can be made to lase near 1.15 {mu}m. (optical fibres, lasers and amplifiers. properties and applications)

  9. Ni-rich precipitates in a lead bismuth eutectic loop

    NASA Astrophysics Data System (ADS)

    Kikuchi, K.; Saito, S.; Hamaguchi, D.; Tezuka, M.

    2010-03-01

    Solidified LBE was sampled from the specimens, electro-magnetic pump, filter, drain valve and oxygen sensor at the JAEA Lead Bismuth Loop-1 (JLBL-1) where the structural material was made of SS316. The concentration of Ni, Fe and Cr in LBE were analyzed by the Inductive Coupled Plasma atomic emission spectrometer. It was concluded that the solution of Ni into LBE was not saturated although the concentration of Fe and Cr almost achieved to the values in the literature. A needle-type structure appeared on the surface of solidified LBE inside the tube specimens. It was found to be Ni-rich precipitates by X-ray analyses (Field Emission Scanning Electron Microscope, FE-SEM). LBE samples collected from a circulating loop after discharging did not show the amount of impurities equivalent to the LBE bulk property.

  10. Structural investigation of Zn doped sodium bismuth borate glasses

    NASA Astrophysics Data System (ADS)

    Bhatia, V.; Kumar, D.; Singh, D.; Singh, S. P.

    2016-05-01

    A series of Bismuth Borate Oxide Glass samples with composition x(ZnO):(15-x)Na2O:15Bi2O3:70B2O3 (variation in x is from 6 to 12 mole %) have been prepared by conventional melt quenching technique. All the chemicals used were of Analytical Grade. In order to verify the amorphous nature of the prepared samples the X-Ray Diffraction (XRD) was done. The physical and structural properties have been explored by using the techniques such as density, molar volume and FTIR in order to understand the effect of alkali and transition metal ions on the structure of these glasses. The results obtained by these techniques are in good agreement to one another and with literature as well. With the increase in the content of ZnO, the increase in density and some variations in structural coordination (ratio of BO3 & BO4 structural units) have been observed.

  11. Dielectric behavior of barium modified strontium bismuth titanate ceramic

    SciTech Connect

    Nayak, P.; Badapanda, T.; Anwar, S.; Panigrahi, S.

    2014-04-24

    Barium Modified Strontium Bismuth Titanate(SBT) ceramic with general formula Sr1−xBaxBi4Ti4O15 is prepared by solid state reaction route. The structural analysis of the ceramics was done by X-ray diffraction technique. The X-ray patterns show that all the compositions are of single phase with orthorhombic structure. The temperature dependent dielectric behavior shows that the transition temperature decreases with Ba content but the maximum dielectric constant increases. The decreases of the transition with increase in Ba{sup 2+} ion, may be due to the decrease of orthorhombicity by the incorporation of Ba{sup 2+} ion in SBT lattice.

  12. Structural properties of bismuth-bearing semiconductor alloys

    NASA Technical Reports Server (NTRS)

    Berding, M. A.; Sher, A.; Chen, A.-B.; Miller, W. E.

    1988-01-01

    The structural properties of bismuth-bearing III-V semiconductor alloys InPBi, InAsBi, and InSbBi were studied theoretically. Bond energies, bond lengths, and strain coefficients were calculated for pure AlBi, GaBi, and InBi compounds and their alloys, and predictions were made for the mixing enthalpies, miscibility gaps, and critical metastable-to-stable material transition temperatures. Miscibility calculations indicate that InSbBi will be the most miscible, and the InPBi will be the the most difficult to mix. However, calculations of the hardness of the Bi compounds indicate that, once formed, the InPBi alloy will be harder than the other Bi alloys and substantially harder than the currently favored narrow-gap semiconductor HgCdTe.

  13. EXAFS Study of Semimetal-Semiconductor Transition of Bismuth Clusters

    SciTech Connect

    Ikemoto, H.; Yoshida, S.; Sogoh, J.; Miyanaga, T.

    2007-02-02

    Extended X-ray absorption fine structure (EXAFS) measurements of bismuth clusters in the temperature range of 23 -300 K have been performed using synchrotron radiation in order to investigate the size dependent phase transition. The inter-atomic distances around 3.0 A and 3.6 A are attributed to the nearest neighbors within the layer and between layers, respectively. EXAFS functions were analysed by the curve fitting method within a symmetric distribution approximation. The nearest neighbor distance of the 0.5 nm thick films is shorter than that of the 300 nm thick films at all the temperatures, which is related to the reduction of the inter-layer correlation.

  14. Quantum interferences and edge states in Bismuth based Josephson junctions

    NASA Astrophysics Data System (ADS)

    Murani, Anil; Sengupta, Shamashis; Kasumov, Alik; Gueron, Sophie; Bouchiat, Hélène; MESO group Team

    We have investigated proximity induced superconductivity in single crystal bismuth nanowires connected to superconducting electrodes with a high critical field. I will specially report recent results on nanowires whose crystalline orientation could be determined by electron diffraction. At low temperature a supercurrent is measured which persists up to the critical field of the electrodes and exhibits sample dependent fast squid-like oscillations (period one to few hundred gauss) modulated by slower (few thousand Gauss) oscillations. We attribute this striking result to the appearance of 1D topological edge channels on special surfaces of Bi due to its strong spin-orbit coupling, in addition to a strong Zeeman effect caused by an unusually high g-factor.

  15. Alkaline extraction of polonium from liquid lead bismuth eutectic

    NASA Astrophysics Data System (ADS)

    Heinitz, S.; Neuhausen, J.; Schumann, D.

    2011-07-01

    The production of highly radiotoxic polonium isotopes poses serious safety concerns for the development of future nuclear systems cooled by lead bismuth eutectic (LBE). In this paper it is shown that polonium can be extracted efficiently from LBE using a mixture of alkaline metal hydroxides (NaOH + KOH) in a temperature range between 180 and 350 °C. The extraction ratio was analyzed for different temperatures, gas blankets and phase ratios. A strong dependence of the extraction performance on the redox properties of the cover gas was found. While hydrogen facilitates the removal of polonium, oxygen has a negative influence on the extraction. These findings open new possibilities to back up the safety of future LBE based nuclear facilities.

  16. Lead-bismuth eutectic as advanced reactor collant : operational experience

    SciTech Connect

    Woloshun, K. A.; Watts, V.; Li, N.

    2004-01-01

    Some proposed advanced reactor concepts would be cooled by lead or lead-bismuth eutectic (LBE). An LBE test loop was designed and built at Los Alamos to develop the engineering and materials technology necessary to successfully implement LBE as a coolant (Fig. 1). Operational since December 2001, this test loop has been used to develop and demonstrate safe operation, oxygen concentration and metal corrosion control, instrumentation, thermal-hydraulic performance of heat exchangers and recuperators, and free convection and forced pumping. This paper discusses the technology development and lessons learned from the operation of this facility. A LBE test loop has been operational since December 2001. Using procedures, training, and engineering controls, this loop has operated without an accident. Continuous improvements in operation procedures and instrumentation over these years have resulted in a facility of high reliability, providing the groundwork for the use of LBE as a reactor coolant for temperatures up to 550 C.

  17. A route to fabricate single crystalline bismuth nanowire arrays with different diameters

    NASA Astrophysics Data System (ADS)

    Li, Liang; Zhang, Yong; Li, Guanghai; Zhang, Lide

    2003-09-01

    Single crystalline bismuth nanowire arrays in anodic alumina membrane have been fabricated by pulsed electrodeposition. The nanowires of different diameters were obtained by changing the electrical parameter of the pulsed electrodeposition using anodic alumina membrane as template with the same pore size. X-ray diffraction and TEM analysis show that the bismuth nanowires are single crystalline with highly preferential orientation, and the diameter of nanowires increases with increasing the relaxation time of pulse. The growth mechanism of nanowires was discussed.

  18. Comparison of radiation shielding ratios of nano-sized bismuth trioxide and molybdenum

    NASA Astrophysics Data System (ADS)

    Cho, J. H.; Kim, M. S.; Rhim, J. D.

    2015-07-01

    In this study, radiation shielding fibers using non-hazardous nano-sized bismuth trioxide and molybdenum instead of lead were developed and evaluated. Among the elements with high densities and atomic numbers, non-hazardous elements such as bismuth trioxide and molybdenum were chosen as a shielding element. Then, bismuth trioxide (Bi2O3) with average particle size 1-500 µm was ball milled for 10 min to produce a powdered form of nanoparticles with average particle size of 10-100 nm. Bismuth trioxide nanoparticles were dispersed to make a colloidal suspension, followed by spreading and hardening onto one or two sides of fabric, to create the radiation shielding fabric. The thicknesses of the shielding sheets using nano-sized bismuth and molybdenum were 0.4 and 0.7 mm. According to the lead equivalent test of X-ray shielding products suggested by KS, the equivalent dose was measured, followed by calculation of the shielding rate. The shielding rate of bismuth with 0.4 mm thickness and at 50 kVp was 90.5%, which is comparable to lead of 0.082 mm thickness. The shielding rate of molybdenum was 51.89%%, which is comparable to lead of 0.034 mm. At a thickness of 0.7 mm, the shielding rate of bismuth was 98.73%, equivalent to 0.101 mm Pb, whereas the shielding rate of molybdenum was 74.68%, equivalent to 0.045 mm Pb. In conclusion, the radiation shielding fibers using nano-sized bismuth developed in this study are capable of reducing radiation exposure by X-ray and its low-dose scatter ray.

  19. Influence of cooling on a bismuth-doped fiber laser and amplifier performance.

    PubMed

    Kalita, Mridu P; Yoo, Seongwoo; Sahu, Jayanta K

    2009-11-01

    We characterize bismuth-doped fibers under different excitation wavelengths. The fiber laser performance at 1179 nm was investigated, incorporating different cooling arrangements. Effective heat extraction can reduce the temperature-dependent unsaturable loss in fiber, resulting in increased laser performance. The operation of a bismuth-doped fiber amplifier at 1179 nm, at both low and high input signals, is also examined. The amplifier efficiency and the saturation power both depend on effective fiber cooling. PMID:19881653

  20. Determination of trimethylbismuth in the human body after ingestion of colloidal bismuth subcitrate.

    PubMed

    Boertz, Jens; Hartmann, Louise Michele; Sulkowski, Margareta; Hippler, Joerg; Mosel, Frank; Diaz-Bone, Roland Arturo; Michalke, Klaus; Rettenmeier, Albert Wolfgang; Hirner, Alfred Vitalis

    2009-02-01

    Biological methylation and hydride formation of metals and metalloids are ubiquitous environmental processes that can lead to the formation of chemical species with significantly increased mobility and toxicity. Whereas much is known about the interaction of metal(loid)s with microorganisms in environmental settings, little information has been gathered on respective processes inside the human body as yet. Here, we studied the biotransformation and excretion of bismuth after ingestion of colloidal bismuth subcitrate (215 mg of bismuth) to 20 male human volunteers. Bismuth absorption in the stomach and upper intestine was very low, as evidenced by the small quantity of bismuth eliminated via the renal route. Total bismuth concentrations in blood increased rapidly in the first hour after ingestion. Most of the ingested bismuth was excreted via feces during the study period. Trace levels of the metabolite trimethylbismuth [(CH(3))(3)Bi] were detected via low temperaturegas chromatography/inductively coupled plasma-mass spectrometry in blood samples and in exhaled air samples. Concentrations were in the range of up to 2.50 pg/ml (blood) and 0.8 to 458 ng/m(3) (exhaled air), with high interindividual variation being observed. Elimination routes of bismuth were exhaled air (up to 0.03 per thousand), urine (0.03-1.2%), and feces. The site of (CH(3))(3)Bi production could not be identified in the present study, but the intestinal microflora seems to be involved in this biotransformation if accompanying ex vivo studies are taken into consideration. PMID:18981168

  1. Optical properties of active bismuth centres in silica fibres containing no other dopants

    SciTech Connect

    Bufetov, Igor' A; Semenov, S L; Vel'miskin, V V; Firstov, Sergei V; Dianov, Evgenii M; Bufetova, G A

    2010-09-10

    Optical fibre preforms and fibres with a bismuth-doped silica core containing no other dopants have been fabricated by the powder-in-tube technique. The optical loss has been measured for the first time in such fibres in a wide spectral range, from 190 to 1700 nm. We have studied the luminescence of active bismuth centres and the luminescence lifetime for some of their bands in both the preforms and the fibres drawn out from them. (optical fibres)

  2. Polonium problem in lead-bismuth flow target

    SciTech Connect

    Pankratov, D.V.; Yefimov, E.I.; Bugreev, M.I.

    1996-06-01

    Alpha-active polonium nuclides Po198 - Po210 are formed in a lead-bismuth target as results of reactions Bi{sup 209}(n,{gamma})Bi{sup 210} {yields} Po{sup 210}, Bi{sup 209}(p,xn)Po{sup 210} {yields} Po{sup 210 {minus} x} (x = 1-12), Pb{sup 208}({alpha},xn) {yields} Po{sup 210 {minus} x + 2} (x = 2-14). The most important nuclides are Po-210 (T{sub {1/2}}=138.4 day), Po-209 (T{sub {1/2}}=102 years) and Po-208 (T{sub {1/2}}=2.9 years). Polonium activity of the circuit for SINQ - conditions is about 15,000 Ci after 1-year operation. Polonium radiation hazard is connected with its output from the coolant and formation of aerosol and surface alpha-activity after the circuit break-down for repair works or in accidents. One of the important issues of polonium removal system creation is containing and storing polonium removed. Its storage in solidified alkaline is not expedient because of secondary neutron formation as a result of ({alpha},n) - reaction on oxygen and sodium nucleus. The estimations carried out demonstrated that by polonium concentration {approx} 100 Ci/l neutron current on the container surface can reach {approx} 10{sup 4}n/(cm{sup 2}s). Concentration and storage of polonium in solidified lead-bisumth seems the most convenient. The calculations demonstrated that in a 100 l container 50,000 Ci of polonium can be stored (as much as 3 times more than 1-year polonium product in SINQ-conditions) under temperature in the container less than melting point of lead bismuth (the wall temperature is about 100{degrees}C).

  3. Ferroelectric properties of niobium-doped strontium bismuth tantalate films

    NASA Astrophysics Data System (ADS)

    Golosov, D. A.; Zavadski, S. M.; Kolos, V. V.; Turtsevich, A. S.

    2016-01-01

    The characteristics of ferroelectric thin films of strontium bismuth tantalate (SBT) and niobium-doped strontium bismuth tantalate (SBTN) deposited by radio-frequency (RF) magnetron sputtering on Pt/TiO2/SiO2/Si substrates were investigated. For the formation of the structure of the ferroelectric material, the deposited films were subjected to a subsequent annealing at temperatures of 970-1070 K in an O2 atmosphere. The results of the X-ray diffraction analysis demonstrated that, in contrast to SBT films, in which the Aurivillius phase is formed only at annealing temperatures of 1050-1070 K, the formation of this phase in SBTN films is observed already at a temperature of 970 K. The dependences of the dielectric permittivity, remanent polarization, and coercive force of the SBT and SBTN films on the subsequent annealing conditions were determined. It was found that, upon doping of the SBT films with niobium, the remanent polarization increases by a factor of approximately three, the Curie temperature increases by 50 K, and the dielectric permittivity also increases. It was revealed that, in contrast to the SBT films, the polarization of the SBTN films is observed already at an annealing temperature of approximately 970 K. It was shown that the replacement of SBT films by SBTN films in the manufacture of high-density nonvolatile ferroelectric randomaccess memory (FeRAM) capacitor modules makes it possible to decrease the synthesis temperature from 1070 to 990-1000 K, which improves the compatibility with the planar technology of semiconductor devices. However, it turned out that an increase in the coercive field makes niobium-doped SBT films less attractive for the use in FeRAM.

  4. Devitfrification Properties Of Bismuth Borate Glasses Doped With Trivalent Ions

    SciTech Connect

    Khanna, Atul; Bajaj, Anu

    2010-12-01

    Bismuth borate glasses and crystalline phases have outstanding luminescent and nonlinear optical properties; therefore there is lot of interest in their preparation and characterization. In this study we report the crystallization properties of bismuth borate glasses doped with trivalent ions. Glasses of the composition: xBi{sub 2}O{sub 3}-(100-x)B{sub 2}O{sub 3} (x = 20, 25, 30, 37.5, 40, 50, 60 and 66 mol %) and 40Bi{sub 2}O{sub 3}-1Tv{sub 2}O{sub 3}-59B{sub 2}O{sub 3}(where Tv = Al, Nd and Eu) were prepared by melt quench technique and devitrified by heat treatment above their glass transition temperatures for several hours. The crystalline phases produced were characterized by FTIR absorption spectroscopy, DTA and X-ray diffraction. Bi{sub 3}B{sub 5}O{sub 12} was found to be the predominant phase in all crystallized samples containing Bi{sub 2}O{sub 3} concentration of {<=}40 mol %, at higher Bi{sub 2}O{sub 3} concentration, we observed the formation of Bi{sub 4}B{sub 2}O{sub 9} phase. Glasses with Bi{sub 2}O{sub 3} concentration of {<=}37.5 mol % produced Bi{sub 2}B{sub 8}O{sub 15} phase on crystallization. The metastable BiBO{sub 3}-I phase was formed by short duration heat treatment (less than 5 hours) of the initial glass sample. Doping with rare earth ions like Eu{sup 3+} and Nd{sup 3+} promotes the formation of BiBO{sub 3}-II phase while Al{sup 3+} doping suppresses it.

  5. High-mobility surface states and conductance fluctuations in Bismuth Telluro-Sulfide topological insulator devices

    NASA Astrophysics Data System (ADS)

    Trivedi, Tanuj; Sonde, Sushant; Movva, Hema C. P.; Banerjee, Sanjay K.

    Since the experimental discovery of three-dimensional topological insulators (TI), (Bi,Sb)2(Se,Te)3 binary compounds are the principal material systems to explore TI physics. However, transport experiments studying surface-states are complicated by parallel bulk conductivity contribution, which is expected to improve for ternary and quaternary chalcogenide compounds of Bi and Sb. A promising alternative is the Sulfur-based tetradymite with an ideal formula of Bi2Te2S, which has received little attention. We present van der Waals epitaxial growth and magnetotransport in Bismuth Telluro-Sulfide (BTS) crystalline nanosheets. Gating-enhanced Weak-antilocalization (WAL) and Universal Conductance Fluctuations (UCF) are observed in BTS devices. Empirical modeling of the data shows the existence of two-dimensional surface transport. A three-channel Hall conductivity model is proposed, which is utilized in conjunction with an extended-WAL analysis, showing the presence of a high-mobility surface component and indication for separation of transport channels in BTS devices. Our growth and comprehensive transport experiments demonstrate BTS as a promising candidate TI material.

  6. Thermal transport in bismuth telluride quintuple layer: mode-resolved phonon properties and substrate effects

    PubMed Central

    Shao, Cheng; Bao, Hua

    2016-01-01

    The successful exfoliation of atomically-thin bismuth telluride (Bi2Te3) quintuple layer (QL) attracts tremendous research interest in this strongly anharmonic quasi-two-dimensional material. The thermal transport properties of this material are not well understood, especially the mode-wise properties and when it is coupled with a substrate. In this work, we have performed molecular dynamics simulations and normal mode analysis to study the mode-resolved thermal transport in freestanding and supported Bi2Te3 QL. The detailed mode-wise phonon properties are calculated and the accumulated thermal conductivities with respect to phonon mean free path (MFP) are constructed. It is shown that 60% of the thermal transport is contributed by phonons with MFP longer than 20 nm. Coupling with a-SiO2 substrate leads to about 60% reduction of thermal conductivity. Through varying the interfacial coupling strength and the atomic mass of substrate, we also find that phonon in Bi2Te3 QL is more strongly scattered by interfacial potential and its transport process is less affected by the dynamics of substrate. Our study provides an in-depth understanding of heat transport in Bi2Te3 QL and is helpful in further tailoring its thermal property through nanostructuring. PMID:27263656

  7. Radiochemical determination of rare Earth elements in proton-irradiated lead-bismuth eutectic.

    PubMed

    Hammer, Bernadette; Neuhausen, Jörg; Boutellier, Viktor; Wohlmuther, Michael; Türler, Andreas; Schumann, Dorothea

    2015-06-01

    Various types of proton-irradiated lead-bismuth eutectic (LBE) samples from the MEGAPIE prototype spallation target were analyzed concerning their content of (148)Gd, (173)Lu, and (146)Pm by use of α- and γ-spectrometry. A radiochemical separation procedure was developed to isolate the lanthanide fraction and to prepare thin samples for α-ray measurement. The results prove a substantial depletion of these three elements in bulk samples, whereas accumulation on the LBE/steel-interfaces was observed. The amount of material accumulated on surfaces was roughly estimated by relating the values measured on the sample surfaces to the total surface of the inner target walls. The amount of (148)Gd, (173)Lu, and (146)Pm was then quantified by summing up the contributions from every sample type. The results show a reasonable agreement with theoretical predictions. The obtained results are of utmost importance for the evaluation of the performance of high-power spallation targets, especially concerning the residual nuclide production, the physicochemical behavior of the produced radionuclides during operation, and in terms of an intermediate or final disposal. PMID:25938905

  8. Thermal transport in bismuth telluride quintuple layer: mode-resolved phonon properties and substrate effects

    NASA Astrophysics Data System (ADS)

    Shao, Cheng; Bao, Hua

    2016-06-01

    The successful exfoliation of atomically-thin bismuth telluride (Bi2Te3) quintuple layer (QL) attracts tremendous research interest in this strongly anharmonic quasi-two-dimensional material. The thermal transport properties of this material are not well understood, especially the mode-wise properties and when it is coupled with a substrate. In this work, we have performed molecular dynamics simulations and normal mode analysis to study the mode-resolved thermal transport in freestanding and supported Bi2Te3 QL. The detailed mode-wise phonon properties are calculated and the accumulated thermal conductivities with respect to phonon mean free path (MFP) are constructed. It is shown that 60% of the thermal transport is contributed by phonons with MFP longer than 20 nm. Coupling with a-SiO2 substrate leads to about 60% reduction of thermal conductivity. Through varying the interfacial coupling strength and the atomic mass of substrate, we also find that phonon in Bi2Te3 QL is more strongly scattered by interfacial potential and its transport process is less affected by the dynamics of substrate. Our study provides an in-depth understanding of heat transport in Bi2Te3 QL and is helpful in further tailoring its thermal property through nanostructuring.

  9. Geophex airborne unmanned survey system

    SciTech Connect

    Won, I.J.; Taylor, D.W.A.

    1995-03-01

    The purpose of this effort is to design, construct, and evaluate a portable, remotely-piloted, airborne, geophysical survey system. This nonintrusive system will provide {open_quotes}stand-off{close_quotes} capability to conduct surveys and detect buried objects, structures, and conditions of interest at hazardous locations. This system permits two operators to rapidly conduct geophysical characterization of hazardous environmental sites. During a survey, the operators remain remote from, but within visual distance, of, the site. The sensor system never contacts the Earth, but can be positioned near the ground so that weak anomalies can be detected.

  10. Airborne wavemeter validation and calibration

    NASA Technical Reports Server (NTRS)

    Goad, Joseph H., Jr.; Rinsland, Pamela L.; Kist, Edward H., Jr.; Geier, Erika B.; Banziger, Curtis G.

    1992-01-01

    This manuscript outlines a continuing effort to validate and verify the performance of an airborne autonomous wavemeter for tuning solid state lasers to a desired wavelength. The application is measuring the vertical profiles of atmospheric water vapor using a differential absorption lidar (DIAL) technique. Improved wavemeter performance data for varying ambient temperatures are presented. This resulted when the electronic grounding and shielding were improved. The results with short pulse duration lasers are also included. These lasers show that similar performance could be obtained with lasers operating in the continuous and the pulsed domains.

  11. High sensitive airborne radioiodine monitor.

    PubMed

    Ogata, Yoshimune; Yamasaki, Tadashi; Hanafusa, Ryuji

    2013-11-01

    Airborne radioiodine monitoring includes a problem in that commercial radioactive gas monitors have inadequate sensitivity. To solve this problem, we designed a highly sensitive monitoring system. The higher counting efficiency and lower background made it possible to perform the low-level monitoring. The characteristics of the system were investigated using gaseous (125)I. The minimum detectable activity concentration was 1 × 10(-4)Bq cm(-3) for 1 min counting, which is one tenth of the legal limit for the radiation controlled areas in Japan. PMID:23602709

  12. Geophex Airborne Unmanned Survey System

    SciTech Connect

    Won, I.J.; Keiswetter, D.

    1995-10-01

    The purpose of this effort is to design, construct, and evaluate a portable, remotely-piloted, airborne, geophysical survey system. This non-intrusive system will provide {open_quotes}stand-off{close_quotes} capability to conduct surveys and detect buried objects, structures, and conditions of interest at hazardous locations. This system permits rapid geophysical characterization of hazardous environmental sites. During a survey, the operators remain remote from, but within visual distance of, the site. The sensor system never contacts the Earth, but can be positioned near the ground so that weak geophysical anomalies can be detected.

  13. Cyberinfrastructure for Airborne Sensor Webs

    NASA Technical Reports Server (NTRS)

    Freudinger, Lawrence C.

    2009-01-01

    Since 2004 the NASA Airborne Science Program has been prototyping and using infrastructure that enables researchers to interact with each other and with their instruments via network communications. This infrastructure uses satellite links and an evolving suite of applications and services that leverage open-source software. The use of these tools has increased near-real-time situational awareness during field operations, resulting in productivity improvements and the collection of better data. This paper describes the high-level system architecture and major components, with example highlights from the use of the infrastructure. The paper concludes with a discussion of ongoing efforts to transition to operational status.

  14. Biological monitoring of airborne pollution

    SciTech Connect

    Ditz, D.W. )

    1990-01-01

    Common plants such as grasses, mosses, and even goldenrod may turn out to have a new high-tech role as monitors of airborne pollution from solid waste incinerators. Certain plants that respond to specific pollutants can provide continuous surveillance of air quality over long periods of time: they are bio-indicators. Other species accumulate pollutants and can serve as sensitive indicators of pollutants and of food-chain contamination: they are bio-accumulators. Through creative use of these properties, biological monitoring can provide information that cannot be obtained by current methods such as stack testing.

  15. Airborne Research Experience for Educators

    NASA Astrophysics Data System (ADS)

    Costa, V. B.; Albertson, R.; Smith, S.; Stockman, S. A.

    2009-12-01

    The Airborne Research Experience for Educators (AREE) Program, conducted by the NASA Dryden Flight Research Center Office of Education in partnership with the AERO Institute, NASA Teaching From Space Program, and California State University Fullerton, is a complete end-to-end residential research experience in airborne remote sensing and atmospheric science. The 2009 program engaged ten secondary educators who specialize in science, technology, engineering or mathematics in a 6-week Student Airborne Research Program (SARP) offered through NSERC. Educators participated in collection of in-flight remote sensor data during flights aboard the NASA DC-8 as well as in-situ research on atmospheric chemistry (bovine emissions of methane); algal blooms (remote sensing to determine location and degree of blooms for further in-situ analysis); and crop classification (exploration of how drought conditions in Central California have impacted almond and cotton crops). AREE represents a unique model of the STEM teacher-as-researcher professional development experience because it asks educators to participate in a research experience and then translate their experiences into classroom practice through the design, implementation, and evaluation of instructional materials that emphasize the scientific research process, inquiry-based investigations, and manipulation of real data. Each AREE Master Educator drafted a Curriculum Brief, Teachers Guide, and accompanying resources for a topic in their teaching assignment Currently, most professional development programs offer either a research experience OR a curriculum development experience. The dual nature of the AREE model engaged educators in both experiences. Educators’ content and pedagogical knowledge of STEM was increased through the review of pertinent research articles during the first week, attendance at lectures and workshops during the second week, and participation in the airborne and in-situ research studies, data

  16. Simultaneous solution-based generation and characterization of crystalline bismuth thin film by femtosecond laser spectroscopy

    NASA Astrophysics Data System (ADS)

    Zhu, Liangdong; Saha, Sumit; Liu, Weimin; Wang, Yanli; Keszler, Douglas A.; Fang, Chong

    2015-08-01

    We demonstrate generation and characterization of crystalline bismuth thin film from triphenyl bismuth in methanol. Upon ultraviolet (267 nm) femtosecond laser irradiation of the solution, a thin film of elemental bismuth forms on the inner side of the sample cuvette, confirmed by detection of the coherent A1g optical phonon mode of crystalline bismuth at ˜90 cm-1. Probe pulses at 267 and 400 nm are used to elucidate the excited state potential energy surface and photochemical reaction coordinate of triphenyl bismuth in solution with femtosecond resolution. The observed phonon mode blueshifts with increasing irradiation time, likely due to the gradual thickening of nascent bismuth thin film to ˜80 nm in 90 min. From transient absorption with the 400 nm probe, we observe a dominant ˜4 ps decay time constant of the excited-state absorption signal, which is attributed to a characteristic metal-ligand bond-weakening/breaking intermediate enroute to crystalline metallic thin film from the solution precursor molecules. Our versatile optical setup thus opens an appealing avenue to characterize the laser-induced crystallization process in situ and prepare high-quality thin films and nanopatterns directly from solution phase.

  17. Simultaneous solution-based generation and characterization of crystalline bismuth thin film by femtosecond laser spectroscopy

    SciTech Connect

    Zhu, Liangdong; Keszler, Douglas A.; Fang, Chong; Saha, Sumit; Liu, Weimin; Wang, Yanli

    2015-08-10

    We demonstrate generation and characterization of crystalline bismuth thin film from triphenyl bismuth in methanol. Upon ultraviolet (267 nm) femtosecond laser irradiation of the solution, a thin film of elemental bismuth forms on the inner side of the sample cuvette, confirmed by detection of the coherent A{sub 1g} optical phonon mode of crystalline bismuth at ∼90 cm{sup −1}. Probe pulses at 267 and 400 nm are used to elucidate the excited state potential energy surface and photochemical reaction coordinate of triphenyl bismuth in solution with femtosecond resolution. The observed phonon mode blueshifts with increasing irradiation time, likely due to the gradual thickening of nascent bismuth thin film to ∼80 nm in 90 min. From transient absorption with the 400 nm probe, we observe a dominant ∼4 ps decay time constant of the excited-state absorption signal, which is attributed to a characteristic metal-ligand bond-weakening/breaking intermediate enroute to crystalline metallic thin film from the solution precursor molecules. Our versatile optical setup thus opens an appealing avenue to characterize the laser-induced crystallization process in situ and prepare high-quality thin films and nanopatterns directly from solution phase.

  18. Zerovalent bismuth nanoparticles inhibit Streptococcus mutans growth and formation of biofilm

    PubMed Central

    Hernandez-Delgadillo, Rene; Velasco-Arias, Donaji; Diaz, David; Arevalo-Niño, Katiushka; Garza-Enriquez, Marianela; De la Garza-Ramos, Myriam A; Cabral-Romero, Claudio

    2012-01-01

    Background and methods Despite continuous efforts, the increasing prevalence of resistance among pathogenic bacteria to common antibiotics has become one of the most significant concerns in modern medicine. Nanostructured materials are used in many fields, including biological sciences and medicine. While some bismuth derivatives has been used in medicine to treat vomiting, nausea, diarrhea, and stomach pain, the biocidal activity of zerovalent bismuth nanoparticles has not yet been studied. The objective of this investigation was to analyze the antimicrobial activity of bismuth nanoparticles against oral bacteria and their antibiofilm capabilities. Results Our results showed that stable colloidal bismuth nanoparticles had 69% antimicrobial activity against Streptococcus mutans growth and achieved complete inhibition of biofilm formation. These results are similar to those obtained with chlorhexidine, the most commonly used oral antiseptic agent. The minimal inhibitory concentration of bismuth nanoparticles that interfered with S. mutans growth was 0.5 mM. Conclusion These results suggest that zerovalent bismuth nanoparticles could be an interesting antimicrobial agent to be incorporated into an oral antiseptic preparation. PMID:22619547

  19. Viability of Bismuth as a Green Substitute for Lead in Jacketed .357 Magnum Revolver Bullets

    NASA Astrophysics Data System (ADS)

    Jenkins, Joel

    In seeking to develop environmentally friendly lead-free non-toxic bullets, the research ballistically evaluated the performance of copper-jacketed handgun bullets containing a pure bismuth core. The lead was first removed from 140 grain Hornady(TM) XTPRTM bullets of 38 caliber (.357 diameter) by melting. The empty jackets were then refilled with pure bismuth, including the forming of a correctly sized hollow-point cavity. Due to the lower density of bismuth as compared to lead, the bismuth-cored bullets consistently weighed 125 gains. Conveniently this allowed direct comparison to commercially available 125 grain Hornady(TM) XTPRTM lead-cored bullets of 38 caliber. Both bismuth-cored and lead-cored versions of the 125 grain bullets had identical nose dimensions and jacket material, the only dimensional difference being the bullet length below the cannelure. Shooting took place at an outdoor range using a 357 Magnum Ruger(TM) SP101RTM revolver with 3" barrel as the test weapon. FBI protocols were followed when firing through clothing, wallboard, plywood, steel plates and laminated glass. Wound paths and bullets were captured in ballistic gelatin, with data collected for velocity, penetration, expansion, and weight retention. Bismuth compared favorably with lead in all but the laminated glass test, where it under penetrated due to jacket separation.

  20. A novel structure photonic crystal fiber based on bismuth-oxide for optical parametric amplification

    NASA Astrophysics Data System (ADS)

    Jin, Cang; Yuan, Jinhui; Yu, Chongxiu

    2010-11-01

    The heavy metal oxide glasses containing bismuth such as bismuth sesquioxide show unique high refractive index. In addition, the bismuth-oxide based glass does not include toxic elements such as Pb, As, Se, Te, and exhibits well chemical, mechanical and thermal stability. Hence, it is used to fabricate high nonlinear fiber for nonlinear optical application. Although the bismuth-oxide based high nonlinear fiber can be fusion-spliced to conventional silica fibers and have above advantages, yet it suffers from large group velocity dispersion because of material chromatic dispersion which restricts its utility. In regard to this, the micro-structure was introduced to adjust the dispersion of bismuth-oxide high nonlinear fiber in the 1550nm wave-band. In this paper, a hexagonal solid-core micro-structure is developed to balance its dispersion and nonlinearity. Our simulation and calculation results show that the bismuth-oxide based photonic crystal fiber has near zero dispersion around 1550nm where the optical parametric amplification suitable wavelength is. Its dispersion slop in the communication wavelength range is also relatively flat. Moreover, both nonlinear coefficient and model filed distribution were simulated, respectively.

  1. Data fusion techniques for object space classification using airborne laser data and airborne digital photographs

    NASA Astrophysics Data System (ADS)

    Park, Joong Yong

    The objective of this research is to investigate possible strategies for the fusion of airborne laser data with passive optical data for object space classification. A significant contribution of our work is the development and implementation of a data-level fusion technique, direct digital image georeferencing (DDIG). In DDIG, we use navigation data from an integrated system (composed of global positioning system (GPS) and inertial measurement unit (IMU)) to project three-dimensional data points measured with the University of Florida's airborne laser swath mapping (ALSM) system onto digital aerial photographs. As an underlying math model, we use the familiar collinearity condition equations. After matching the ALSM object space points to their corresponding image space pixels, we resample the digital photographs using cubic convolution techniques. We call the resulting images pseudo-ortho-rectified images (PORI) because they are orthographic at the ground surface but still exhibit some relief displacement for elevated objects; and because they have been resampled using a interpolation technique. Our accuracy tests on these PORI images show that they are planimetrically correct to about 0.4 meters. This accuracy is sufficient to remove most of the effects of the central perspective projection and enable a meaningful fusion of the RGB data with the height and intensity data produced by the laser. PORI images may also be sufficiently accurate for many other mapping applications, and may in some applications be an attractive alternative to traditional photogrammetric techniques. A second contribution of our research is the development of several strategies for the fusion of data from airborne laser and camera systems. We have conducted our work within the sensor fusion paradigm formalized in the optical engineering community. Our work explores the fusion of these two types of data for precision mapping applications. Specifically, we combine three different types of

  2. Airborne Visible Laser Optical Communications Program (AVLOC)

    NASA Technical Reports Server (NTRS)

    Ward, J. H.

    1975-01-01

    The design, development, and operation of airborne and ground-based laser communications and laser radar hardware is described in support of the Airborne Visible Laser Optical Communication program. The major emphasis is placed on the development of a highly flexible test bed for the evaluation of laser communications systems techniques and components in an operational environment.

  3. Global Test Range: Toward Airborne Sensor Webs

    NASA Technical Reports Server (NTRS)

    Mace, Thomas H.; Freudinger, Larry; DelFrate John H.

    2008-01-01

    This viewgraph presentation reviews the planned global sensor network that will monitor the Earth's climate, and resources using airborne sensor systems. The vision is an intelligent, affordable Earth Observation System. Global Test Range is a lab developing trustworthy services for airborne instruments - a specialized Internet Service Provider. There is discussion of several current and planned missions.

  4. Airborne Relay-Based Regional Positioning System

    PubMed Central

    Lee, Kyuman; Noh, Hongjun; Lim, Jaesung

    2015-01-01

    Ground-based pseudolite systems have some limitations, such as low vertical accuracy, multipath effects and near-far problems. These problems are not significant in airborne-based pseudolite systems. However, the monitoring of pseudolite positions is required because of the mobility of the platforms on which the pseudolites are mounted, and this causes performance degradation. To address these pseudolite system limitations, we propose an airborne relay-based regional positioning system that consists of a master station, reference stations, airborne relays and a user. In the proposed system, navigation signals are generated from the reference stations located on the ground and are relayed via the airborne relays. Unlike in conventional airborne-based systems, the user in the proposed system sequentially estimates both the locations of airborne relays and his/her own position. Therefore, a delay due to monitoring does not occur, and the accuracy is not affected by the movement of airborne relays. We conducted several simulations to evaluate the performance of the proposed system. Based on the simulation results, we demonstrated that the proposed system guarantees a higher accuracy than airborne-based pseudolite systems, and it is feasible despite the existence of clock offsets among reference stations. PMID:26029953

  5. The Continuous wavelet in airborne gravimetry

    NASA Astrophysics Data System (ADS)

    Liang, X.; Liu, L.

    2013-12-01

    Airborne gravimetry is an efficient method to recover medium and high frequency band of earth gravity over any region, especially inaccessible areas, which can measure gravity data with high accuracy,high resolution and broad range in a rapidly and economical way, and It will play an important role for geoid and geophysical exploration. Filtering methods for reducing high-frequency errors is critical to the success of airborne gravimetry due to Aircraft acceleration determination based on GPS.Tradiontal filters used in airborne gravimetry are FIR,IIR filer and so on. This study recommends an improved continuous wavelet to process airborne gravity data. Here we focus on how to construct the continuous wavelet filters and show their working principle. Particularly the technical parameters (window width parameter and scale parameter) of the filters are tested. Then the raw airborne gravity data from the first Chinese airborne gravimetry campaign are filtered using FIR-low pass filter and continuous wavelet filters to remove the noise. The comparison to reference data is performed to determinate external accuracy, which shows that continuous wavelet filters applied to airborne gravity in this thesis have good performances. The advantages of the continuous wavelet filters over digital filters are also introduced. The effectiveness of the continuous wavelet filters for airborne gravimetry is demonstrated through real data computation.

  6. A Simple Method for Collecting Airborne Pollen

    ERIC Educational Resources Information Center

    Kevan, Peter G.; DiGiovanni, Franco; Ho, Rong H.; Taki, Hisatomo; Ferguson, Kristyn A.; Pawlowski, Agata K.

    2006-01-01

    Pollination is a broad area of study within biology. For many plants, pollen carried by wind is required for successful seed set. Airborne pollen also affects human health. To foster studies of airborne pollen, we introduce a simple device--the "megastigma"--for collecting pollen from the air. This device is flexible, yielding easily obtained data…

  7. Airborne Oceanographic Lidar (AOL) (Global Carbon Cycle)

    NASA Technical Reports Server (NTRS)

    2003-01-01

    This bimonthly contractor progress report covers the operation, maintenance and data management of the Airborne Oceanographic Lidar and the Airborne Topographic Mapper. Monthly activities included: mission planning, sensor operation and calibration, data processing, data analysis, network development and maintenance and instrument maintenance engineering and fabrication.

  8. Meeting Review: Airborne Aerosol Inlet Workshop

    NASA Technical Reports Server (NTRS)

    Baumgardner, Darrel; Huebert, Barry; Wilson, Chuck

    1991-01-01

    Proceedings from the Airborne Aerosol Inlet Workshop are presented. The two central topics of discussion were the role of aerosols in atmospheric processes and the difficulties in characterizing aerosols. The following topics were discussed during the working sessions: airborne observations to date; identification of inlet design issues; inlet modeling needs and directions; objectives for aircraft experiments; and future laboratory and wind tunnel studies.

  9. Bismuth Undecahydro-closo-dodecaborane: A Retainable Intermediate of B-H Bond Activation by Bismuth(III) Cations.

    PubMed

    Zimmermann, Lucas W; Van, Nguyen-Duc; Gudat, Dietrich; Schleid, Thomas

    2016-01-26

    The [B12 H12](2-) anion shows an extensive substitutional chemistry based on its three-dimensional aromaticity. The replacement of functional groups can be attained by electrophilically induced substitution caused by Brønsted or Lewis acidic electrophiles (e.g. Pt(2+)). Until now, it was impossible to structurally characterize a metal-substituted [B12 H12](2-) cage. When an aqueous solution containing both Bi(3+) cations and [B12 H12](2-) anions was heated, the charge-neutral bismuth undecahydro-closo-dodecaborane BiB12 H11 was obtained, representing a new class of metalated [B12 H12](2-) clusters. The title compound was characterized by single-crystal X-ray diffraction and NMR spectroscopic methods. Compared to the typical B-H bond, the short B-Bi single bond (230 pm) exhibits inverted polarity. PMID:26676462

  10. EUFAR the unique portal for airborne research in Europe

    NASA Astrophysics Data System (ADS)

    Gérard, Elisabeth; Brown, Philip

    2016-04-01

    , the website offers easy navigation, and user friendly functionalities. New features also include a section on news and airborne research stories to keep users up-to-date on EUFAR's activities, a career section, photo galleries, and much more. By elaborating new solutions for the web portal, EUFAR continues to serve as an interactive and dynamic platform bringing together experts, early-stage researchers, operators, data users, industry and other stakeholders in the airborne research community. A main focus of the current project is the establishment of a sustainable legal structure for EUFAR. This is critical to ensuring the continuity of EUFAR and securing, at the least, partial financial independence from the European Commission who has been funding the project since its start. After carefully examining different legal forms relevant for EUFAR, the arguments are strongly in favour of establishing an International non-profit Association under the Belgian law (AISBL). Together with the implementation of an Open Access scheme by means of resource-sharing to support the mobility of personnel across countries envisaged in 2016, such a sustainable structure would contribute substantially toward broadening the user base of existing airborne research facilities in Europe and mobilising additional resources for this end. In essence, this would cement EUFAR's position as the key portal for airborne research in Europe.

  11. Bismuth-doped optical fibers and fiber lasers for a spectral region of 1600-1800  nm.

    PubMed

    Firstov, Sergei; Alyshev, Sergey; Melkumov, Mikhail; Riumkin, Konstantin; Shubin, Alexey; Dianov, Evgeny

    2014-12-15

    Bismuth-doped optical fibers and fiber lasers operating in 1625-1775 nm range have been developed for the first time to the best of our knowledge. Now the existing bismuth-doped lasers, including the result presented in this Letter, can cover O, E, S, C, L, and U telecommunication bands. In addition, new data on the nature of the bismuth-related active center were obtained and discussed. PMID:25503032

  12. The network modifier and former role of the bismuth ions in the bismuth-lead-germanate glasses

    NASA Astrophysics Data System (ADS)

    Rada, M.; Rus, L.; Rada, S.; Culea, E.; Rusu, T.

    2014-11-01

    The present work is focused on the enhancement of network former environment in lead-germanate glasses by bismuth ions doping. A series of bismuth-lead-germanate glasses with the xBi2O3·(100 - x)[7GeO2·3PbO] composition glass where 0 ⩽ x ⩽ 30 mol% Bi2O3 were synthesized by melt-quenching method. The FTIR, UV-VIS spectroscopy and cyclic voltammetry were conducted on these samples to evaluate the doping effect of structure of the host matrix network. Our results indicate that direct incorporation of Bi2O3 into the lead-germanate network modifies the lead-germanate network and the internal structure of glass network is rearranged. The structural flexibility of the lead-germanate network is possible due to its incapacity to accommodate with the excess of oxygen atoms and the creation of bridging oxygen ions. Optical gap energy and refractive index were obtained as a function of Bi2O3 content. Gap energy values decrease as Bi2O3 content increased from 0 to 10 mol%. Further increase of Bi2O3 concentration beyond 10 mol% increased the gap energy values. These behaviors of the glass system can be explained by two mechanisms: (i) for x ⩽ 10 mol% Bi2O3 - increase of degree of disorder of the host matrix because Bi2O3 is network modifier and (ii) for x > 10 mol% - Bi2O3 acts as a network former. Cyclic voltammetry measurements using the glass system with 10Bi2O3·90[7GeO2·3PbO] composition as working electrode show the mobility of the lead ions, in agreement with UV-VIS data.

  13. A theoretical model for airborne radars

    NASA Astrophysics Data System (ADS)

    Faubert, D.

    1989-11-01

    This work describes a general theory for the simulation of airborne (or spaceborne) radars. It can simulate many types of systems including Airborne Intercept and Airborne Early Warning radars, airborne missile approach warning systems etc. It computes the average Signal-to-Noise ratio at the output of the signal processor. In this manner, one obtains the average performance of the radar without having to use Monte Carlo techniques. The model has provision for a waveform without frequency modulation and one with linear frequency modulation. The waveform may also have frequency hopping for Electronic Counter Measures or for clutter suppression. The model can accommodate any type of encounter including air-to-air, air-to-ground (look-down) and rear attacks. It can simulate systems with multiple phase centers on receive for studying advanced clutter or jamming interference suppression techniques. An Airborne Intercept radar is investigated to demonstrate the validity and the capability of the model.

  14. CNR LARA project, Italy: Airborne laboratory for environmental research

    NASA Technical Reports Server (NTRS)

    Bianchi, R.; Cavalli, R. M.; Fiumi, L.; Marino, C. M.; Pignatti, S.

    1995-01-01

    The increasing interest for the environmental problems and the study of the impact on the environment due to antropic activity produced an enhancement of remote sensing applications. The Italian National Research Council (CNR) established a new laboratory for airborne hyperspectral imaging, the LARA Project (Laboratorio Aero per Ricerche Ambientali - Airborne Laboratory for Environmental Research), equipping its airborne laboratory, a CASA-212, mainly with the Daedalus AA5000 MIVIS (Multispectral Infrared and Visible Imaging Spectrometer) instrument. MIVIS's channels, spectral bandwidths, and locations are chosen to meet the needs of scientific research for advanced applications of remote sensing data. MIVIS can make significant contributions to solving problems in many diverse areas such as geologic exploration, land use studies, mineralogy, agricultural crop studies, energy loss analysis, pollution assessment, volcanology, forest fire management and others. The broad spectral range and the many discrete narrow channels of MIVIS provide a fine quantization of spectral information that permits accurate definition of absorption features from a variety of materials, allowing the extraction of chemical and physical information of our environment. The availability of such a hyperspectral imager, that will operate mainly in the Mediterranean area, at the present represents a unique opportunity for those who are involved in environmental studies and land-management to collect systematically large-scale and high spectral-spatial resolution data of this part of the world. Nevertheless, MIVIS deployments will touch other parts of the world, where a major interest from the international scientific community is present.

  15. Geophex Airborne Unmanned Survey System

    SciTech Connect

    Won, I.L.; Keiswetter, D.

    1995-12-31

    Ground-based surveys place personnel at risk due to the proximity of buried unexploded ordnance (UXO) items or by exposure to radioactive materials and hazardous chemicals. The purpose of this effort is to design, construct, and evaluate a portable, remotely-piloted, airborne, geophysical survey system. This non-intrusive system will provide stand-off capability to conduct surveys and detect buried objects, structures, and conditions of interest at hazardous locations. During a survey, the operators remain remote from, but within visual distance of, the site. The sensor system never contacts the Earth, but can be positioned near the ground so that weak geophysical anomalies can be detected. The Geophex Airborne Unmanned Survey System (GAUSS) is designed to detect and locate small-scale anomalies at hazardous sites using magnetic and electromagnetic survey techniques. The system consists of a remotely-piloted, radio-controlled, model helicopter (RCH) with flight computer, light-weight geophysical sensors, an electronic positioning system, a data telemetry system, and a computer base-station. The report describes GAUSS and its test results.

  16. The effect of aluminium on the post-anneal concentration of ion implanted bismuth in silica thin films

    NASA Astrophysics Data System (ADS)

    Southern-Holland, R.; Halsall, M. P.; Crowe, I. F.; Yang, P.; Gwilliam, R. M.

    2015-12-01

    We present a study of bismuth and aluminium co-implanted silica thin films and the effectiveness of post implantation annealing at activating Bismuth related photoluminescence. The only emission seen in photoluminescence from any of the samples was centred at 1160 nm and is of the kind generally reported as due to silicon dislocation loops. In particular, the layers did not exhibit the broad NIR emission in photoluminescence as reported by other authors in Bismuth doped silica fibres. In order to study the retention of the Bismuth in the layers after annealing Rutherford Backscattering measurements were conducted on the samples, these found that the concentration of bismuth in the samples was greatly reduced following the annealing process when compared to the concentration implanted and explains why we measured no emission from bismuth. The concentration of bismuth remaining in the sample post anneal depended on the initial implant doses of bismuth and aluminium. We propose that aluminium plays the role of increasing the solubility of bismuth in oxide but that this was not sufficient in our samples to observe the photoemission reported for fibre materials.

  17. Synthesis and characterization of bismuth telluride based nanostructured thermoelectric composite materials

    NASA Astrophysics Data System (ADS)

    Keshavarz Khorasgani, Mohsen

    single phase alloy. Scanning electron microscope images show that the average grain size of p-type (Bi0.2Sb 0.8)2Te3 composites containing 0.2, 0.4 and 0.8 wt% MoS2 nano-particles, under otherwise identical extrusion conditions, is reduced by a factor around four. Scherer's formula applied to x-ray diffraction data indicates that after the hot extrusion process, the average crystallite size in composites increases only by 10% (˜ 18 nm) compared to about 400% growth (˜ 80 nm) observed in the single phase bismuth telluride based alloy. Smaller crystallites, as expected, lead to a reduction of the thermal conductivity in these nanocomposites (˜1.4 W/m˙K at 450 K for 0.4 wt.% MoS2) when compared to the conventional alloy (˜1.8 W/m˙K). The structural changes in the nanocomposites characterized by mechanical spectroscopy in the temperature range 293-540 K show an increase of the internal friction accompanied by a systematic reduction of its activation energy with increase in MoS2 content, which is an indication of higher density of crystal defects in the nanocomposites that largely contribute to the internal friction background. Investigation of TE properties shows a reduction of the room temperature figure of merit (ZT values) from 0.9 to 0.7 due to a lower power factor. However, once above 370 K, the figure of merit of alloys containing MoS2 nano-particles surpasses that of single phase (Bi0.2Sb0.8)2Te3, due to a more pronounced reduction in the thermal conductivity at temperatures above the cross point of the ZT values. Remarkably, we have demonstrated that adding nano-particles of MoS 2 to bismuth telluride based alloys is an approach to significantly reduce the grain size of the matrix resulting in an important thermal conductivity decrease. The enhanced ZT values above 370 K in nanocomposites show the preeminent achievement of this approach, although further study is required to obtain optimum transport properties, and boost up the ZT more effectively.

  18. Airborne electromagnetic imaging of discontinuous permafrost

    USGS Publications Warehouse

    Minsley, B.J.; Abraham, J.D.; Smith, B.D.; Cannia, J.C.; Voss, C.I.; Jorgenson, M.T.; Walvoord, M.A.; Wylie, B.K.; Anderson, L.; Ball, L.B.; Deszcz-Pan, M.; Wellman, T.P.; Ager, T.A.

    2012-01-01

    The evolution of permafrost in cold regions is inextricably connected to hydrogeologic processes, climate, and ecosystems. Permafrost thawing has been linked to changes in wetland and lake areas, alteration of the groundwater contribution to streamflow, carbon release, and increased fire frequency. But detailed knowledge about the dynamic state of permafrost in relation to surface and groundwater systems remains an enigma. Here, we present the results of a pioneering ???1,800 line-kilometer airborne electromagnetic survey that shows sediments deposited over the past ???4 million years and the configuration of permafrost to depths of ???100 meters in the Yukon Flats area near Fort Yukon, Alaska. The Yukon Flats is near the boundary between continuous permafrost to the north and discontinuous permafrost to the south, making it an important location for examining permafrost dynamics. Our results not only provide a detailed snapshot of the present-day configuration of permafrost, but they also expose previously unseen details about potential surface-groundwater connections and the thermal legacy of surface water features that has been recorded in the permafrost over the past ???1,000 years. This work will be a critical baseline for future permafrost studies aimed at exploring the connections between hydrogeologic, climatic, and ecological processes, and has significant implications for the stewardship of Arctic environments. ?? 2012 by the American Geophysical Union.

  19. ARIES: NASA Langley's Airborne Research Facility

    NASA Technical Reports Server (NTRS)

    Wusk, Michael S.

    2002-01-01

    In 1994, the NASA Langley Research Center (LaRC) acquired a B-757-200 aircraft to replace the aging B-737 Transport Systems Research Vehicle (TSRV). The TSRV was a modified B-737-100, which served as a trailblazer in the development of glass cockpit technologies and other innovative aeronautical concepts. The mission for the B-757 is to continue the three-decade tradition of civil transport technology research begun by the TSRV. Since its arrival at Langley, this standard 757 aircraft has undergone extensive modifications to transform it into an aeronautical research "flying laboratory". With this transformation, the aircraft, which has been designated Airborne Research Integrated Experiments System (ARIES), has become a unique national asset which will continue to benefit the U.S. aviation industry and commercial airline customers for many generations to come. This paper will discuss the evolution of the modifications, detail the current capabilities of the research systems, and provide an overview of the research contributions already achieved.

  20. Assessing New Airborne Gravimetry Collected over New Zealand

    NASA Astrophysics Data System (ADS)

    Amos, M.; McCubbine, J.; Caratori Tontini, F.; Winefield, R.

    2014-12-01

    Land Information New Zealand, in conjunction with GNS Science and Victoria University, has recently completed a ten month airborne gravimetry campaign across New Zealand. The survey has provided, for the first time, consistent regular coverage across the shallow coastal areas and rough topographic regions that have previously been extremely difficult to survey. This data will be used to update the gravimetric geoid model that forms the basis of New Zealand's official vertical datum. In this contribution we present the results of the survey campaign and evaluate the accuracy of the data collected over 2013/14.

  1. Electrical transport measurements of individual bismuth nanowires and carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Jang, Wan Young

    Nanostructures are defined by reducing dimensions. When the reduced size of materials is comparable to the Fermi wavelength, quantum size effect occurs. Dimensionality plays a critical role in determining the electronic properties of materials, because the density of states of materials is quite different. Nanowires have attracted much attention recently due to their fundamental interest and potential applications. A number of materials have been tried. Among them, bismuth has unique properties. Bismuth has the smallest effective mass as small as 0.001me. This small effective mass of Bi nanowires allows one to observe the quantum confinement effect easily. Also Bi nanowires are good candidates for a low-dimensional transport study due to long mean free path. Because of these remarkable properties of Bi nanowires, many efforts have been made to study Bi nanowires. However, because bismuth is extremely sensitive to the oxide, it is very difficult to make a reliable device. So far, array measurements of Bi nanowires have been reported. The study is focused on the synthesis and electric transport measurements of individual Bi nanowires. Bi nanowires are synthesized by electrodeposition using either anodic aluminum oxide (AAO) templates or commercially available track etched polycarbonate membranes (PCTE). The desired nanowire has a heterostructure of Au - Bi - Au. Au wires on both sides serve as contact electrodes with Bi. To extract nanowires from PCTE or AAO, several attempts have been made. Devices consisting of single Bi nanowires grown by hydrothermal method are fabricated and electrical measurements have been carried out after in-situ deposition of Pt electrodes. The temperature dependence of resistance of majority of nanowires increases with decreasing temperature, showing polycrystalline nature of nanowires. However, some nanowires show resistance peaks at low temperature, suggesting quantum size effect (QSE). Magnetoresistance (MR) has also been measured. We

  2. Comparison of Lead-Bismuth and Lead as Coolants for Accelerator Driven Systems

    SciTech Connect

    Bianchi, F.; Mattioda, F.; Meloni, P.

    2002-07-01

    In the framework of the Italian research program TRASCO (TRAsmutazione SCOrie, namely transmutation of radioactive wastes) and of the European research program PDS-XADS (Preliminary Design Study on an eXperimental Accelerator Driven System) the feasibility and operability of gas or liquid metal cooled accelerator driven system prototypes are currently under investigation. Initially the attention of the thermal-hydraulics group of ENEA research centre in Bologna has been focussed toward a lead-bismuth cooled subcritical system under natural or enhanced natural circulation according to the prototype design proposed. The interest in using lead as a coolant, which is characterized by a higher melting point, is explained by the need to increase the plant efficiency for the economic competitiveness, though the higher temperatures pose some technological problems. Moreover, the amount of activation products should result significantly lower. Of course the results obtained and the experience gained analysing the dynamical behaviour of the lead-bismuth cooled system cannot be directly transferred to lead cooled systems. This paper aims at presenting a preliminary comparison of lead-bismuth and lead in a simplified liquid metal cooled subcritical system, mainly from the thermal-hydraulics and system dynamics points of view. By means of the modified RELAP5 version, the dynamical behavior of a lead-bismuth or lead cooled system, which is intended to be a quite accurate representation of the Italian accelerator driven prototype XADS, has been studied. Although a more exhaustive comparison should take into account the necessarily different structural characteristics of lead-bismuth and lead cooled systems, the neutronic feedback on reactor power and also the slightly different neutronic properties of lead-bismuth and lead, the purely thermal-hydraulic analysis presented in this paper has shown that the dynamical behaviour of the XADS does not differ noticeable when lead is used

  3. Dextran coated bismuth-iron oxide nanohybrid contrast agents for computed tomography and magnetic resonance imaging

    PubMed Central

    Naha, Pratap C.; Zaki, Ajlan Al; Hecht, Elizabeth; Chorny, Michael; Chhour, Peter; Blankemeyer, Eric; Yates, Douglas M.; Witschey, Walter R. T.; Litt, Harold I.; Tsourkas, Andrew; Cormode, David P.

    2014-01-01

    Bismuth nanoparticles have been proposed as a novel CT contrast agent, however few syntheses of biocompatible bismuth nanoparticles have been achieved. We herein report the synthesis of composite bismuth-iron oxide nanoparticles (BION) that are based on a clinically approved, dextran-coated iron oxide formulation; the particles have the advantage of acting as contrast agents for both CT and MRI. BION were synthesized and characterized using various analytical methods. BION CT phantom images revealed that the X-ray attenuation of the different formulations was dependent upon the amount of bismuth present in the nanoparticle, while T2-weighted MRI contrast decreased with increasing bismuth content. No cytotoxicity was observed in Hep G2 and BJ5ta cells after 24 hours incubation with BION. The above properties, as well as the yield of synthesis and bismuth inclusion efficiency, led us to select the Bi-30 formulation for in vivo experiments, performed in mice using a micro-CT and a 9.4 T MRI system. X-ray contrast was observed in the heart and blood vessels over a 2 hour period, indicating that Bi-30 has a prolonged circulation half-life. Considerable signal loss in T2-weighted MR images was observed in the liver compared to pre-injection scans. Evaluation of the biodistribution of Bi-30 revealed that bismuth is excreted via the urine, with significant concentrations found in the kidneys and urine. In vitro experiments confirmed the degradability of Bi-30. In summary, dextran coated BION are biocompatible, biodegradable, possess strong X-ray attenuation properties and also can be used as T2-weighted MR contrast agents. PMID:25485115

  4. Airborne lidar measurements of ozone and aerosols during the pacific exploratory mission-tropics A

    NASA Technical Reports Server (NTRS)

    Fenn, Marta A.; Browell, Edward V.; Grant, William B.; Butler, Carolyn F.; Kooi, Susan A.; Clayton, Marian B.; Brackett, Vincent G.; Gregory, Gerald L.

    1998-01-01

    Airborne lidar measurements of aerosol and ozone distributions from the surface to above the tropopause over the South Pacific Ocean are presented. The measurements illustrate large-scale features of the region, and are used to quantify the relative contributions of different ozone sources to the tropospheric ozone budget in this remote region.

  5. Spectroscopic Characterization of Extracellular Polymeric Substances from Escherichia coli and Serratia marcescens: Suppression using Sub-Inhibitory Concentrations of Bismuth Thiols

    SciTech Connect

    Badireddy, Appala R.; Korpol, Bhoom Reddy; Chellam, Shankararaman; Gassman, Paul L.; Engelhard, Mark H.; Lea, Alan S.; Rosso, Kevin M.

    2008-10-21

    Free and capsular EPS produced by Escherichia coli and Serratia marcescens were characterized in detail using Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and Auger electron spectroscopy (AES). Total EPS production decreased upon treatment with sub-inhibitory concentrations of lipophilic bismuth thiols (bismuth dimercaptopropanol, BisBAL; bismuth ethanedithiol, BisEDT; and bismuth pyrithione, BisPYR), BisBAL being most effective. Bismuth thiols also influenced acetylation and carboxylation of polysaccharides in EPS from S. marcescens. Extensive homology between EPS samples in the presence and absence of bismuth was observed with proteins, polysaccharides, and nucleic acids varying predominantly only in the total amount expressed. Second derivative analysis of the amide I region of FTIR spectra revealed decreases in protein secondary structures in the presence of bismuth thiols. Hence, anti-fouling properties of bismuth thiols appear to originate in their ability to suppress O-acetylation and protein secondary structures in addition to total EPS secretion.

  6. Morphology modulated growth of bismuth tungsten oxide nanocrystals

    SciTech Connect

    Yao Shushan; Wei, Jiyong; Huang Baibiao Feng Shengyu; Zhang Xiaoyang; Qin Xiaoyan; Wang Peng; Wang Zeyan; Zhang Qi; Jing Xiangyang; Zhan Jie

    2009-02-15

    Two kinds of bismuth tungsten oxide nanocrystals were prepared by microwave hydrothermal method. The morphology modulation of nanocrystals synthesized with precursor suspension's pH varied from 0.25 (strong acid) to 10.05 (base) was studied. The 3D flower like aggregation of Bi{sub 2}WO{sub 6} nanoflakes was synthesized in acid precursor suspension and the nanooctahedron crystals of Bi{sub 3.84}W{sub 0.16}O{sub 6.24} were synthesized in alkalescent precursor. The dominant crystal is changed from Bi{sub 2}WO{sub 6} to Bi{sub 3.84}W{sub 0.16}O{sub 6.24} when the precursor suspension changes from acid to alkalescence. The growth mechanisms of Bi{sub 2}WO{sub 6} and Bi{sub 3.84}W{sub 0.16}O{sub 6.24} were attributed to the different solubility of WO{sub 4}{sup 2-} and [Bi{sub 2}O{sub 2}]{sup 2+} in precursor suspensions with various pH. For the decomposition of Rhodamine B (RhB) under visible light irradiation ({lambda}>400 nm), different morphology of Bi{sub 2}WO{sub 6} crystal samples obtained by microwavesolvothermal process showed different photocatalytic activity. - Graphical abstract: The morphology modulation of bismuth tungsten oxide nanocrystals synthesized by microwave hydrothermal method with precursor suspension's pH varied from 0.25 (strong acid) to 10.05 (base) was studied. The 3D flower like aggregation of Bi{sub 2}WO{sub 6} nanoflakes and nanooctahedron crystals of Bi{sub 3.84}W{sub 0.16}O{sub 6.24} were prepared. The growth mechanisms of Bi{sub 2}WO{sub 6} and Bi{sub 3.84}W{sub 0.16}O{sub 6.24} were attributed to the different precipitation ability and solubility of H{sub 2}WO{sub 4} and Bi(OH){sub 3} in precursor suspensions with various pH. The photocatalytic evaluation, via the decomposition of Rhodamine B (RhB) under visible light irradiation ({lambda}>420 nm), reveals that nanocrystalline Bi{sub 2}WO{sub 6} samples obtained in different condition exhibit different photocatalytic activities which depend on pH value of the precursor suspensions.

  7. Modis-N airborne simulator

    NASA Technical Reports Server (NTRS)

    Cech, Steven D.

    1992-01-01

    All required work associated with the above referenced contract has been successfully completed at this time. The Modis-N Airborne Simulator has been developed from existing AB184 Wildfire spectrometer parts as well as new detector arrays, optical components, and associated mechanical and electrical hardware. The various instrument components have been integrated into an operational system which has undergone extensive laboratory calibration and testing. The instrument has been delivered to NASA Ames where it will be installed on the NASA ER-2. The following paragraphs detail the specific tasks performed during the contract effort, the results obtained during the integration and testing of the instrument, and the conclusions which can be drawn from this effort.

  8. Airborne imaging spectrometer development tasks

    NASA Astrophysics Data System (ADS)

    Bolten, John

    The tasks that must be completed to design and build an airborne imaging spectrometer are listed. The manpower and resources required to do these tasks must be estimated by the people responsible for that work. The tasks are broken down by instrument subsystem or discipline. The instrument performance can be assessed at various stages during the development. The initial assessment should be done with the preliminary computer model. The instrument calibration facilities should be designed, but no calibration facilities are needed. The intermediate assessment can be done when the front end has been assembled. The preliminary instrument calibration facility should be available at this stage. The final assessment can only be done when the instrument is complete and ready for flight. For this, the final instrument calibration facility and the flight qualification facilities must be ready. The final assessment is discussed in each discipline under the section on integration and test.

  9. Research on MLS airborne antenna

    NASA Technical Reports Server (NTRS)

    Yu, C. L.; Burnside, W. D.

    1976-01-01

    Numerical solutions for the radiation patterns of antennas mounted on aircraft are developed. The airborne antenna problems associated with the Microwave Landing System (MLS) are emphasized. Based on the requirements of the MLS, volumetric pattern solutions are essential. Previous attempts at solving for the volumetric patterns were found to be far too complex and very inefficient. However as a result of previous efforts, it is possible to combine the elevation and roll plane pattern solutions to give the complete volumetric pattern. This combination is described as well as the aircraft simulation models used in the analysis. A numerical technique is presented to aid in the simulation of the aircraft studied. Finally, a description of the input data used in the computer code is given.

  10. Global deposition of airborne dioxin.

    PubMed

    Booth, Shawn; Hui, Joe; Alojado, Zoraida; Lam, Vicky; Cheung, William; Zeller, Dirk; Steyn, Douw; Pauly, Daniel

    2013-10-15

    We present a global dioxin model that simulates one year of atmospheric emissions, transport processes, and depositions to the earth's terrestrial and marine habitats. We map starting emission levels for each land area, and we also map the resulting deposits to terrestrial and marine environments. This model confirms that 'hot spots' of deposition are likely to be in northern Europe, eastern North America, and in parts of Asia with the highest marine dioxin depositions being the northeast and northwest Atlantic, western Pacific, northern Indian Ocean and the Mediterranean. It also reveals that approximately 40% of airborne dioxin emissions are deposited to marine environments and that many countries in Africa receive more dioxin than they produce, which results in these countries being disproportionately impacted. Since human exposure to dioxin is largely through diet, this work highlights food producing areas that receive higher atmospheric deposits of dioxin than others. PMID:23962732

  11. Airborne remote sensing of forest biomes

    NASA Technical Reports Server (NTRS)

    Sader, Steven A.

    1987-01-01

    Airborne sensor data of forest biomes obtained using an SAR, a laser profiler, an IR MSS, and a TM simulator are presented and examined. The SAR was utilized to investigate forest canopy structures in Mississippi and Costa Rica; the IR MSS measured forest canopy temperatures in Oregon and Puerto Rico; the TM simulator was employed in a tropical forest in Puerto Rico; and the laser profiler studied forest canopy characteristics in Costa Rica. The advantages and disadvantages of airborne systems are discussed. It is noted that the airborne sensors provide measurements applicable to forest monitoring programs.

  12. Improvement of filling bismuth for x-ray absorption gratings through the enhancement of wettability

    NASA Astrophysics Data System (ADS)

    Lei, Yaohu; Liu, Xin; Li, Ji; Guo, Jinchuan; Niu, Hanben

    2016-06-01

    Filling materials with high x-ray linear absorption coefficients in high aspect-ratio (HAR) structures is a key process for the fabrication of absorption gratings used in x-ray differential phase-contrast imaging. Bismuth has been chosen as an effective filling material in micro-casting technology, because of its low cost both in price and facility use. However, repellence on structure surfaces against molten bismuth leads to an obstacle in terms of completely filling bismuth into the small-aperture and HAR microstructure formed by photo-assisted electrochemical etching in 5 inch silicon wafers. We propose and implement a novel method of surface modification to completely fill bismuth into these structures with periods of 3 μm and 42 μm, respectively, and as deep as 150 μm. The modified surface with a Bi2O3 layer covering the structure surface, including the side walls, induces an enhanced bismuth filling ratio. The superiority of the method is demonstrated by micrographs which show filled microstructures compared to the previously used method, where only a layer of 100 nm SiO2 was covered. Furthermore, we have observed that the improved micro-casting makes the absorption gratings clean surfaces, and no post treatment is needed.

  13. Electron excitation and autoionisation cross sections for elements of chemically peculiar stars: Study of bismuth

    NASA Astrophysics Data System (ADS)

    Predojević, B.; Pejčev, V.; Šević, D.; Marinković, B. P.

    2014-12-01

    Electron impact excitation from the ground state of bismuth atoms has been studied. A beam of electrons was scattered from a beam of atoms and the intensity of scattered electrons was measured for scattering angles up to 150° and incident electron energies of 40 and 60 eV. Obtained intensities were used for the calculation of relative differential cross sections (DCS). In addition, we recorded the energy loss-spectra at different incident electron energies and scattering angles. These spectra were analysed in order to identify the energy levels of bismuth atom below and above (autoionisation) the first ionization limit in electron spectroscopy. The presence of bismuth was confirmed in spectra of the chemically peculiar (CP) magnetic Ap 73 Dra and HR 465 and nonmagnetic Hg-Mn HR 7775 and χ Lupi stars. The obtained results for relative DCS and identified autoionised energy levels of bismuth were analysed and compared with previous experimental and theoretical data. The connection between our investigations of bismuth and astrophysical measurements are discussed.

  14. Enhanced thermoelectric properties of bismuth sulfide polycrystals prepared by mechanical alloying and spark plasma sintering

    SciTech Connect

    Zhao Lidong; Zhang Boping Liu Weishu; Zhang Hailong; Li Jingfeng

    2008-12-15

    Bismuth sulfide powders were synthesized by mechanical alloying (MA) and then consolidated by spark plasma sintering (SPS) technique. In order to improve the electrical transport properties of bismuth sulfides, the carrier concentration was optimized by modifying chemical composition of sulfur through producing sulfur vacancies, and the carrier mobility was enhanced by a two-step SPS as a hot-forging process through increasing grain orientation. The electrical resistivity of bismuth sulfides was reduced to 10{sup -4} from 10{sup -2} {omega} m by optimizing sulfur content, and further lowered by hot-forging, whereby the power factor was significantly increased from 91 to 254 {mu}W/mK{sup 2}. The hot-forged Bi{sub 2}S{sub 2.90} sample showed the highest ZT=0.11 (at 523 K), which is higher than the reported value. The present work revealed that bismuth sulfide compounds as a promising candidate of thermoelectric materials can be synthesized by a simple process. - Abstract: Electrical properties of bismuth sulfides were improved by optimizing carrier concentration through modifying compositions of sulfur and enhancing carrier mobility through SPSed hot-forging. The ZT value of 0.11 was obtained, which is the maximum reported so far . Display Omitted.

  15. Nanoscale Andreev Reflection Spectroscopy on Bismuth-Chalcogenide Topological Insulators

    NASA Astrophysics Data System (ADS)

    Granstrom, C. R.; Fridman, I.; Liang, R. X.; Lei, H.; Petrovic, C.; Yang, Shuo; Wu, K. H.; Wei, J. Y. T.

    Andreev reflection (AR) is the basic mechanism underlying the superconducting proximity effect which, at the interface between a topological insulator (TI) and a spin-singlet superconductor, can induce chiral p-wave pairing in the TI. Despite this novel importance, it is not well understood how AR is affected by the unique attributes of a three-dimensional TI, namely the Dirac dispersion and helical spin-polarization of its surface states. In this work, we use both s-wave and d-wave superconducting tips to perform AR spectroscopy at 4.2 K on flux-grown Bi2Se3 and Bi2Te3 single crystals, as well as epitaxial Bi2Se3 thin films grown on SrTiO3 substrates by molecular beam epitaxy. These AR measurements are complemented by scanning tunneling spectroscopy, in order to characterize the superconducting tip as well as the doping level and surface condition of the TI sample. Our data are analyzed using BTK theory, in light of the characteristic band structure of bismuth chalcogenides, to elucidate how the band structure affects the AR process. Work supported by: NSERC, CFI-OIT, the Canadian Institute for Advanced Research, and the Department of Energy.

  16. Energy levels scheme simulation of divalent cobalt doped bismuth germanate

    SciTech Connect

    Andreici, Emiliana-Laura; Petkova, Petya; Avram, Nicolae M.

    2015-12-07

    The aim of this paper is to simulate the energy levels scheme for Bismuth Germanate (BGO) doped with divalent cobalt, in order to give a reliable explanation for spectral experimental data. In the semiempirical crystal field theory we first modeled the Crystal Field Parameters (CFPs) of BGO:Cr{sup 2+} system, in the frame of Exchange Charge Model (ECM), with actually site symmetry of the impurity ions after doping. The values of CFPs depend on the geometry of doped host matrix and by parameter G of ECM. First, we optimized the geometry of undoped BGO host matrix and afterwards, that of doped BGO with divalent cobalt. The charges effect of ligands and covalence bonding between cobalt cations and oxygen anions, in the cluster approach, also were taken into account. With the obtained values of the CFPs we simulate the energy levels scheme of cobalt ions, by diagonalizing the matrix of the doped crystal Hamiltonian. Obviously, energy levels and estimated Racah parameters B and C were compared with the experimental spectroscopic data and discussed. Comparison of obtained results with experimental data shows quite satisfactory, which justify the model and simulation schemes used for the title system.

  17. Robust surface state transport in thin bismuth nanoribbons

    NASA Astrophysics Data System (ADS)

    Ning, Wei; Kong, Fengyu; Han, Yuyan; Du, Haifeng; Yang, Jiyong; Tian, Mingliang; Zhang, Yuheng

    2014-11-01

    While a two-dimensional (2D) metallic surface state in bismuth has been proposed, experimental 2D evidence of quantum transport, e.g., angular dependent Shubnikov-de Haas (SdH) oscillations is still lacking. Here, we report the angular-dependent magnetoresistance measurements in single-crystal Bi nanoribbons, and found that both the low-field weak antilocalization behavior and the high-field angle-dependent SdH oscillations follow exactly the 2D character, indicative of the 2D metallic surface states which dominate the transport properties of thin Bi nanoribbons. Moreover, by controllable exposing the ribbons to ambient environment (1 atm and room temperature), the metallic surface states were found to be robust to the oxidation although the carrier density in the surface states are modified after the exposures. These results suggest that the metallic surface states in Bi nanoribbons should be topologically protected which can provide key information in understanding the surface properties of Bi in nanometer scale.

  18. Investigation of solution-processed bismuth-niobium-oxide films

    SciTech Connect

    Inoue, Satoshi; Ariga, Tomoki; Matsumoto, Shin; Onoue, Masatoshi; Miyasako, Takaaki; Tokumitsu, Eisuke; Shimoda, Tatsuya; Chinone, Norimichi; Cho, Yasuo

    2014-10-21

    The characteristics of bismuth-niobium-oxide (BNO) films prepared using a solution process were investigated. The BNO film annealed at 550°C involving three phases: an amorphous phase, Bi₃NbO₇ fluorite microcrystals, and Nb-rich cubic pyrochlore microcrystals. The cubic pyrochlore structure, which was the main phase in this film, has not previously been reported in BNO films. The relative dielectric constant of the BNO film was approximately 140, which is much higher than that of a corresponding film prepared using a conventional vacuum sputtering process. Notably, the cubic pyrochlore microcrystals disappeared with increasing annealing temperature and were replaced with triclinic β-BiNbO₄ crystals at 590°C. The relative dielectric constant also decreased with increasing annealing temperature. Therefore, the high relative dielectric constant of the BNO film annealed at 550°C is thought to result from the BNO cubic pyrochlore structure. In addition, the BNO films annealed at 500°C contained approximately 6.5 atm.% carbon, which was lost at approximately 550°C. This result suggests that the carbon in the BNO film played an important role in the formation of the cubic pyrochlore structure.

  19. Ferroelectric and photocatalytic behavior of bismuth ferrite nano wire

    NASA Astrophysics Data System (ADS)

    William, R. V.; Marikani, A.; Madhavan, D.

    2016-05-01

    Multiferroic bismuth ferrite nanowires are prepared through polyol method with an average diameter of 35 nm with a narrow size distribution. The band gap was determined to be 2.10 eV, indicating their potential application as visible-light-response photo catalyst. The magnificent photocatalytic behaviors of BiFeO3 nanowires are understood from the methyl violet degradation under visible light irradiation. Moreover, the nano-wire takes only a lesser time for the diffusion of electron-hole pair from the surface of the sample. Further the BiFeO3 nano-wire was characterized using XRD, SEM, and U-V. The ferroelectric studies of BiFeO3 nano-wire show a frequency dependent property and maximum coercivity of 2.7 V/cm were achieved with a remanent polarization at 0.5 µC/cm2 at the frequency 4 kHz. The coercivity of BiFeO3 nano wire changes with variation of frequency from 1 kHz to 4 kHz.

  20. Bismuth telluride nanostructures: preparation, thermoelectric properties and topological insulating effect

    NASA Astrophysics Data System (ADS)

    Ashalley, Eric; Chen, Haiyuan; Tong, Xin; Li, Handong; Wang, Zhiming M.

    2015-05-01

    Bismuth telluride is known to wield unique properties for a wide range of device applications. However, as devices migrate to the nanometer scale, significant amount of studies are being conducted to keep up with the rapidly growing nanotechnological field. Bi2Te3 possesses distinctive properties at the nanometer level from its bulk material. Therefore, varying synthesis and characterization techniques are being employed for the realization of various Bi2Te3 nanostructures in the past years. A considerable number of these works have aimed at improving the thermoelectric (TE) figure-of-merit (ZT) of the Bi2Te3 nanostructures and drawing from their topological insulating properties. This paper reviews the various Bi2Te3 and Bi2Te3-based nanostructures realized via theoretical and experimental procedures. The study probes the preparation techniques, TE properties and the topological insulating effects of 0D, 1D, 2D and Bi2Te3 nanocomposites. With several applications as a topological insulator (TI), the topological insulating effect of the Bi2Te3 is reviewed in detail with the time reversal symmetry (TRS) and surface state spins which characterize TIs. Schematics and preparation methods for the various nanostructural dimensions are accordingly categorized.

  1. Quasiparticle electronic structure of bismuth telluride in the GW approximation

    NASA Astrophysics Data System (ADS)

    Kioupakis, Emmanouil; Tiago, Murilo L.; Louie, Steven G.

    2010-12-01

    The quasiparticle band structure of bismuth telluride (Bi2Te3) , an important thermoelectric material that exhibits topologically insulating surface states, is calculated from first principles in the GW approximation. The quasiparticle energies are evaluated in fine detail in the first Brillouin zone using a Wannier-function interpolation method, allowing the accurate determination of the location of the band extrema (which is in the mirror plane) as well as the values of the quasiparticle band gap (0.17 eV) and effective-mass tensors. Spin-orbit interaction effects were included. The valence band exhibits two distinct maxima in the mirror plane that differ by just 1 meV, giving rise to one direct and one indirect band gap of very similar magnitude. The effective-mass tensors are in reasonable agreement with experiment. The Wannier interpolation coefficients can be used for the tight-binding parametrization of the band structure. Our work elucidates the electronic structure of Bi2Te3 and sheds light on its exceptional thermoelectric and topologically insulating properties.

  2. Thermoelectric characterization of individual bismuth selenide topological insulator nanoribbons

    NASA Astrophysics Data System (ADS)

    Tang, Hao; Wang, Xiaomeng; Xiong, Yucheng; Zhao, Yang; Zhang, Yin; Zhang, Yan; Yang, Juekuan; Xu, Dongyan

    2015-04-01

    Bismuth selenide (Bi2Se3) nanoribbons have attracted tremendous research interest recently to study the properties of topologically protected surface states that enable new opportunities to enhance the thermoelectric performance. However, the thermoelectric characterization of individual Bi2Se3 nanoribbons is rare due to the technological challenges in the measurements. One challenge is to ensure good contacts between the nanoribbon and electrodes in order to determine the thermal and electrical properties accurately. In this work, we report the thermoelectric characterization of individual Bi2Se3 nanoribbons via a suspended microdevice method. Through careful measurements, we have demonstrated that contact thermal resistance is negligible after the electron-beam-induced deposition (EBID) of platinum/carbon (Pt/C) composites at the contacts between the nanoribbon and electrodes. It is shown that the thermal conductivity of the Bi2Se3 nanoribbons is less than 50% of the bulk value over the whole measurement temperature range, which can be attributed to enhanced phonon boundary scattering. Our results indicate that intrinsic Bi2Se3 nanoribbons prepared in this work are highly doped n-type semiconductors, and therefore the Fermi level should be in the conduction band and no topological transport behavior can be observed in the intrinsic system.

  3. [Efficient oxidative degradation of tetrabromobisphenol A by silver bismuth oxide].

    PubMed

    Chen, Man-tang; Song, Zhou; Wang, Nan; Ding, Yao-bin; Liao, Hai-xing; Zhu, Li-hua

    2015-01-01

    Silver bismuth oxide(BSO) was prepared by a simple ion exchange-coprecipitation method with AgNO3 and NaBiO, .2H2O as raw materials, and then used to oxidatively degrade tetrabromobisphenol A(TBBPA). Effects of the molar ratio of Ag/Bi during BSO preparation and the BSO dosage on the degradation of TBBPA were investigated. The results showed that under the optimized conditions (i.e., the Ag/Bi molar ratio of 1:1, BSO dosage of 1 g x L(-1), 40 mg x L(-1) of TBBPA was completely degraded and the removal of total organic carbon achieved more than 80% within 7 min. The degradation intermediates of TBBPA were identified by ion chromatography, gas chromatograph-mass spectrometer and X-ray photoelectron spectroscopy. The degradation pathway of TBBPA included the debromination, the cleavage of tert-butyl group and the open epoxidation of benzene ring. Based on a quenching study of NaN3, singlet oxygen was proved to play a dominant role in the TBBPA degradation. PMID:25898666

  4. Quasiparticle electronic structure of bismuth telluride in the GW approximation

    SciTech Connect

    Kioupakis, Emmanouil; Tiago, Murilo L; Louie, Steven G.

    2010-01-01

    The quasiparticle band structure of bismuth telluride Bi2Te3 , an important thermoelectric material that exhibits topologically insulating surface states, is calculated from first principles in the GW approximation. The quasiparticle energies are evaluated in fine detail in the first Brillouin zone using a Wannier-function interpo- lation method, allowing the accurate determination of the location of the band extrema which is in the mirror plane as well as the values of the quasiparticle band gap 0.17 eV and effective-mass tensors. Spin-orbit interaction effects were included. The valence band exhibits two distinct maxima in the mirror plane that differ by just 1 meV, giving rise to one direct and one indirect band gap of very similar magnitude. The effective- mass tensors are in reasonable agreement with experiment. The Wannier interpolation coefficients can be used for the tight-binding parametrization of the band structure. Our work elucidates the electronic structure of Bi2Te3 and sheds light on its exceptional thermoelectric and topologically insulating properties.

  5. Structure and thermoelectric properties of obliquely deposited bismuth films

    SciTech Connect

    Ukhlinov, G.A.; Kosakovskaya, Z. Ya.; Vigdorovich, V.N.

    1986-11-01

    Bismuth films were deposited in a vacuum evaporation equipment at a vacuum of 10/sup -2/ Pa. The microstructure of the films was investigaged by optical and scanning-electron microscopy. The orientation of the crystals was studied with a UEMV-100K electron microscope and a DRON-2 x-ray diffractometer using Fe K..cap alpha.. radiation. We carried out a survey both of the diffractograms of the films to reveal the type of planes parallel to the substrate surface and of the texture patterns from the 0009 reflection by tilting the samples relative to the horizontal axis on a GP-2 tilting attachment. The electrical resistance of the films was measured by the four-probe method and the longitudinal thermo-emf using two probes on a gradient thermoblock. The transverse thermo-emf was determined by irradiating the samples by a heat flux with an intensity of 1 W/cm/sup 2/ from an infrared heating lamp.

  6. Manganese modified structural and optical properties of bismuth silicate glasses

    NASA Astrophysics Data System (ADS)

    Dult, Meenakshi; Kundu, R. S.; Berwal, Neelam; Punia, R.; Kishore, N.

    2015-06-01

    Glass system with compositions xMnO2-(60-x) Bi2O3-40SiO2 have been synthesized by standard melt quench technique. X-ray diffraction patterns confirm the amorphous nature of as-prepared glass samples. The values of density have been measured and molar volume determined is found to decrease with increase in MnO2 content. Theoretical calculations of crystalline volume (Vc) have also been made. The glass transition temperature (Tg) determined using differential scanning calorimetry (DSC) is observed to increase with increase in MnO2 content. The structural analysis has been carried out using FTIR and Raman spectroscopy. In the present glass system, MnO2 acts as network modifier and exists in MnO6 structural units. Bismuth acts both as network former with BiO3 pyramidal units as well as network modifier with BiO6 octahedral units in the present glass system. SiO2 exists in form of SiO4 tetrahedral structural units with two non-bridging oxygens (NBO's). The optical band gap energy (Eg) has been estimated from Tauc's plot for direct transitions, it decreases with increase in manganese content.

  7. Experiments with the low melting indium-bismuth alloy system

    NASA Technical Reports Server (NTRS)

    Krepski, Richard P.

    1992-01-01

    The following is a laboratory experiment designed to create an interest in and to further understanding of materials science. The primary audience for this material is the junior high school or middle school science student having no previous familiarity with the material, other than some knowledge of temperature and the concepts of atoms, elements, compounds, and chemical reactions. The objective of the experiment is to investigate the indium-bismuth alloy system. Near the eutectic composition, the liquidus is well below the boiling point of water, allowing simple, minimal hazard casting experiments. Such phenomena as metal oxidation, formation of intermetallic compound crystals, and an unusual volume increase during solidification could all be directly observed. A key concept for students to absorb is that properties of an alloy (melting point, mechanical behavior) may not correlate with simple interpolation of properties of the pure components. Discussion of other low melting metals and alloys leads to consideration of environmental and toxicity issues, as well as providing some historical context. Wetting behavior can also be explored.

  8. Bismuth Oxide: A New Lithium-Ion Battery Anode

    PubMed Central

    Li, Yuling; Trujillo, Matthias A.; Fu, Engang; Patterson, Brian; Fei, Ling; Xu, Yun; Deng, Shuguang; Smirnov, Sergei; Luo, Hongmei

    2013-01-01

    Bismuth oxide directly grown on nickel foam (p-Bi2O3/Ni) was prepared by a facile polymer-assisted solution approach and was used directly as a lithium-ion battery anode for the first time. The Bi2O3 particles were covered with thin carbon layers, forming network-like sheets on the surface of the Ni foam. The binder-free p-Bi2O3/Ni shows superior electrochemical properties with a capacity of 668 mAh/g at a current density of 800 mA/g, which is much higher than that of commercial Bi2O3 powder (c-Bi2O3) and Bi2O3 powder prepared by the polymer-assisted solution method (p-Bi2O3). The good performance of p-Bi2O3/Ni can be attributed to higher volumetric utilization efficiency, better connection of active materials to the current collector, and shorter lithium ion diffusion path. PMID:24416506

  9. Tributylphosphate Extraction Behavior of Bismuthate-Oxidized Americium

    SciTech Connect

    Mincher; Leigh R. Martin; Nicholas C. Schmitt

    2008-08-01

    Higher oxidation states of americium have long been known; however, options for their preparation in acidic solution are limited. The conventional choice, silver-catalyzed peroxydisulfate, is not useful at nitric acid concentrations above about 0.3 M. We investigated the use of sodium bismuthate as an oxidant for Am3+ in acidic solution. Room-temperature oxidation produced AmO2 2+ quantitatively, whereas oxidation at 80 °C produced AmO2+ quantitatively. The efficacy of the method for the production of oxidized americium was verified by fluoride precipitation and by spectroscopic absorbance measurements. We performed absorbance measurements using a conventional 1 cm cell for high americium concentrations and a 100 cm liquid waveguide capillary cell for low americium concentrations. Extinction coefficients for the absorbance of Am3+ at 503 nm, AmO2+ at 514 nm, and AmO2 2+ at 666 nm in 0.1 M nitric acid are reported. We also performed solvent extraction experiments with the hexavalent americium using the common actinide extraction ligand tributyl phosphate (TBP) for comparison to the other hexavalent actinides. Contact with 30% tributyl phosphate in dodecane reduced americium; it was nevertheless extracted using short contact times. The TBP extraction of AmO2 2+ over a range of nitric acid concentrations is shown for the first time and was found to be analogous to that of uranyl, neptunyl, and plutonyl ions.

  10. Structural investigation of phosphate - bismuth glasses with vanadium

    SciTech Connect

    Stănescu, R.; Vedeanu, N.; Cozar, I. B.; Măgdaş, A.

    2013-11-13

    The xV{sub 2}O{sub 5}(1−dx)[0.5P{sub 2}O{sub 5}⋅0.5Bi{sub 2}O{sub 3}] glass system with 0 ≤ x ≤ 50 mol% is investigated by IR and Raman spectroscopy. Both P{sub 2}O{sub 5} and Bi{sub 2}O{sub 3} oxides are known as network formers, but Bi{sub 2}O{sub 3} is an unconventional one. At low content of vanadium oxide (x ≤ 5 mol%), both IR and Raman spectra are dominated by vibration bands characteristics to structural groups of phosphate and bismuthate lattices. Due to the network modifier role, vanadium oxide acts mainly on the Bi{sub 2}O{sub 3} network allowing the phosphate groups to impose their characteristics absorption bands in spectra. These bands are strongly reduced for x ≥ 20 mol% due to the phosphate network depolymerization and the appearance of new vibrations characteristic to P-O-V, Bi-O-V and V-O-V groups showing the network former role of V{sub 2}O{sub 5}.

  11. Thermoelectric characterization of individual bismuth selenide topological insulator nanoribbons.

    PubMed

    Tang, Hao; Wang, Xiaomeng; Xiong, Yucheng; Zhao, Yang; Zhang, Yin; Zhang, Yan; Yang, Juekuan; Xu, Dongyan

    2015-04-21

    Bismuth selenide (Bi2Se3) nanoribbons have attracted tremendous research interest recently to study the properties of topologically protected surface states that enable new opportunities to enhance the thermoelectric performance. However, the thermoelectric characterization of individual Bi2Se3 nanoribbons is rare due to the technological challenges in the measurements. One challenge is to ensure good contacts between the nanoribbon and electrodes in order to determine the thermal and electrical properties accurately. In this work, we report the thermoelectric characterization of individual Bi2Se3 nanoribbons via a suspended microdevice method. Through careful measurements, we have demonstrated that contact thermal resistance is negligible after the electron-beam-induced deposition (EBID) of platinum/carbon (Pt/C) composites at the contacts between the nanoribbon and electrodes. It is shown that the thermal conductivity of the Bi2Se3 nanoribbons is less than 50% of the bulk value over the whole measurement temperature range, which can be attributed to enhanced phonon boundary scattering. Our results indicate that intrinsic Bi2Se3 nanoribbons prepared in this work are highly doped n-type semiconductors, and therefore the Fermi level should be in the conduction band and no topological transport behavior can be observed in the intrinsic system. PMID:25798738

  12. Magnetoelectric Effect in Ceramics Based on Bismuth Ferrite

    NASA Astrophysics Data System (ADS)

    Jartych, Elżbieta; Pikula, Tomasz; Kowal, Karol; Dzik, Jolanta; Guzdek, Piotr; Czekaj, Dionizy

    2016-04-01

    Solid-state sintering method was used to prepare ceramic materials based on bismuth ferrite, i.e., (BiFeO3)1 - x -(BaTiO3) x and Bi1 - x Nd x FeO3 solid solutions and the Aurivillius Bi5Ti3FeO15 compound. The structure of the materials was examined using X-ray diffraction, and the Rietveld method was applied to phase analysis and structure refinement. Magnetoelectric coupling was registered in all the materials using dynamic lock-in technique. The highest value of magnetoelectric coupling coefficient α ME was obtained for the Bi5Ti3FeO15 compound ( α ME ~ 10 mVcm-1 Oe-1). In the case of (BiFeO3)1 - x -(BaTiO3) x and Bi1 - x Nd x FeO3 solid solutions, the maximum α ME is of the order of 1 and 2.7 mVcm-1 Oe-1, respectively. The magnitude of magnetoelectric coupling is accompanied with structural transformation in the studied solid solutions. The relatively high magnetoelectric effect in the Aurivillius Bi5Ti3FeO15 compound is surprising, especially since the material is paramagnetic at room temperature. When the materials were subjected to a preliminary electrical poling, the magnitude of the magnetoelectric coupling increased 2-3 times.

  13. Robust surface state transport in thin bismuth nanoribbons

    PubMed Central

    Ning, Wei; Kong, Fengyu; Han, Yuyan; Du, Haifeng; Yang, Jiyong; Tian, Mingliang; Zhang, Yuheng

    2014-01-01

    While a two-dimensional (2D) metallic surface state in bismuth has been proposed, experimental 2D evidence of quantum transport, e.g., angular dependent Shubnikov-de Haas (SdH) oscillations is still lacking. Here, we report the angular-dependent magnetoresistance measurements in single-crystal Bi nanoribbons, and found that both the low-field weak antilocalization behavior and the high-field angle-dependent SdH oscillations follow exactly the 2D character, indicative of the 2D metallic surface states which dominate the transport properties of thin Bi nanoribbons. Moreover, by controllable exposing the ribbons to ambient environment (1 atm and room temperature), the metallic surface states were found to be robust to the oxidation although the carrier density in the surface states are modified after the exposures. These results suggest that the metallic surface states in Bi nanoribbons should be topologically protected which can provide key information in understanding the surface properties of Bi in nanometer scale. PMID:25404036

  14. Structural properties of bismuth-bearing semiconductor alloys

    NASA Technical Reports Server (NTRS)

    Berding, M. A.; Sher, A.; Chen, A. B.

    1986-01-01

    The structural properties of bismuth-bearing III-V semiconductor alloys are addressed. Because the Bi compounds are not known to form zincblende structures, only the anion-substituted alloys InPBi, InAsBi, and InSbBi are considered candidates as narrow-gap semiconductors. Miscibility calculations indicate that InSbBi will be the most miscible, and InPBi, with the large lattice mismatch of the constituents, will be the most difficult to mix. Calculations of the hardness of the Bi compounds indicate that, once formed, the InPBi alloy will be harder than the other Bi alloys, and substantially harder than the currently favored narrow-gap semiconductor HgCdTe. Thus, although InSbBi may be an easier material to prepare, InPBi promises to be a harder material. Growth of the Bi compounds will require high effective growth temperatures, probably attainable only through the use of nonequilibrium energy-assisted epitaxial growth techniques.

  15. Dielectric and Impedance Spectroscopy of Barium Bismuth Vanadate Ferroelectrics

    NASA Astrophysics Data System (ADS)

    Sutar, B. C.; Choudhary, R. N. P.; Das, Piyush R.

    2014-07-01

    Structural, micro-structural and electrical properties of barium bismuth vanadate Ba(Bi0.5V0.5)O3 ceramics were investigated. X-ray diffraction (XRD) analysis of the prepared material confirmed the formation of the compound with monoclinic crystal system. Scanning electron microscopy (SEM) of the compound exhibits well-defined grains that are uniformly distributed throughout the surface of the sample. Dielectric properties of the compound were studied as a function of temperature at different frequencies. An observation of dielectric anomaly at 295 °C is due to ferroelectric phase transition that was later confirmed by the appearance of hysteresis loop. Detailed studies of complex impedance spectroscopy have provided a better understanding of the relaxation process and correlations between the microstructure-electrical properties of the materials. The nature of frequency dependence of ac conductivity obeys the Debye power law. The dc conductivity, calculated from the ac conductivity spectrum, shows the negative temperature coefficient of resistance behavior similar to that of a semiconductor.

  16. Frequency-dependent conductivity in bismuth-vanadate glassy semiconductors

    NASA Astrophysics Data System (ADS)

    Ghosh, Aswini

    1990-01-01

    The first measurements are reported for the frequency-dependent (ac) conductivity (real as well as imaginary parts) for various compositions of the bismuth-vanadate glassy semiconductors in the frequency range 102-105 Hz and in the temperature range 77-420 K. The behavior of the ac conductivity is broadly similar to what has been observed previously in many other types of amorphous semiconductors, namely, nearly linear frequency dependence and weak temperature dependence. The experimental results are analyzed with reference to various theoretical models based on quantum-mechanical tunneling and classical hopping over barriers. The analysis shows that the temperature dependence of the ac conductivity is consistent with the simple quantum-mechanical tunneling model at low temperatures; however, this model completely fails to predict the observed temperature dependence of the frequency exponent. The overlapping-large-polaron tunneling model can explain the temperature dependence of the frequency exponent at low temperatures. Fitting of this model to the low-temperature data yields a reasonable value of the wave-function decay constant. However, this model predicts the temperature dependence of the ac conductivity much higher than what actual data showed. The correlated barrier hopping model is consistent with the temperature dependence of both the ac conductivity and its frequency exponent. This model provides reasonable values of the maximum barrier heights but higher values of characteristic relaxation times.

  17. Mechanically Activated Synthesis of Nanocrystalline Powders of Ferroelectric Bismuth Vanadate

    NASA Astrophysics Data System (ADS)

    Shantha, K.; Subbanna, G. N.; Varma, K. B. R.

    1999-01-01

    Mechanical milling of a stoichiometric mixture of Bi2O3and V2O5yielded nanosized powders of bismuth vanadate, Bi2VO5.5(BiV). Structural evolution of the desired BiV phase, through an intermediate product (BiVO4), was monitored by subjecting the powders, ball milled for various durations to X-ray powder diffraction (XRD), differential thermal analysis (DTA), and transmission electron microscopic (TEM) studies. XRD studies indicate that the relative amount of the BiV phase present in the ball-milled mixture increases with increase in milling time and its formation reaches completion within 54 h of milling. Assynthesized powders were found to stabilize in the high-temperature tetragonal (γ) phase. DTA analyses of the powders milled for various durations suggest that the BiV phase-formation temperature decreases with increase in milling time. The nanometric size (30 nm) of the crystallites in the final product was confirmed by TEM and XRD studies. TEM studies clearly demonstrate the growth of BiV onBi2O3crystallites.

  18. Bismuth nanoparticles integration into heavy metal electrochemical stripping sensor.

    PubMed

    Cadevall, Miquel; Ros, Josep; Merkoçi, Arben

    2015-08-01

    Between their many applications bismuth nanoparticles (BiNPs) are showing interest as pre-concentrators in heavy metals detection while being applied as working electrode modifiers used in electrochemical stripping analysis. From the different reported methods to synthesize BiNPs we are focused on the typical polyol method, largely used in these types of metallic and semi-metallic nanoparticles. This study presents the strategy for an easy control of the shape and size of BiNPs including nanocubes, nanosferes and triangular nanostructures. To improve the BiNP size and shape, different reducing agents (ethylene glycol or sodium hypophosphite) and stabilizers (polyvinyl pyrrolidone, PVP, in different amounts) have been studied. The efficiency of BiNPs for heavy metals analysis in terms of detection sensitivity while being used as modifiers of screen-printed carbon electrodes including the applicability of the developed device in real sea water samples is shown. A parallel study between the obtained nanoparticles and their performance in heavy metal sensing has been described in this communication. PMID:25994368

  19. Airborne measurements of spatial NO2 distributions during AROMAT

    NASA Astrophysics Data System (ADS)

    Meier, Andreas Carlos; Seyler, André; Schönhardt, Anja; Richter, Andreas; Ruhtz, Thomas; Lindemann, Carsten; Burrows, John P.

    2015-04-01

    Nitrogen oxides, NOx (NOx = NO + NO2) play a key role in tropospheric chemistry. In addition to their directly harmful effects on the respiratory system of living organisms, they influence the levels of tropospheric ozone and contribute to acid rain and eutrophication of ecosystems. As they are produced in combustion processes, they can serve as an indicator for anthropogenic air pollution. In September 2014 several European research groups conducted the ESA funded Airborne ROmanian Measurements of Aerosols and Trace gases (AROMAT) campaign to test and intercompare newly developed airborne observation sytsems dedicated to air quality satellite validation studies. The IUP Bremen contributed to this campaign with its Airborne imaging DOAS instrument for Measurements of Atmospheric Pollution (AirMAP) on board a Cessna 207 turbo, operated by the FU Berlin. AirMAP allows the retrieval of integrated NO2 column densities in a stripe below the aircraft at a fine spatial resolution of up to 30 x 80 m2, at a typical flight altitude. Measurements have been performed over the city of Bucharest, creating for the first time high spatial resolution maps of Bucharest's NO2 distribution in a time window of approx. 2 hours. The observations were synchronised with ground-based car MAX-DOAS measurements for comparison. In addition, measurements were taken over the city of Berlin, Germany and at the Rovinari power plant, Romania. In this work the results of the research flights will be presented and conclusions will be drawn on the quality of the measurements, their applicability for satellite data validation and possible improvements for future measurements.

  20. The development of a bismuth feed system for the very high Isp thruster with anode layer VHITAL program

    NASA Technical Reports Server (NTRS)

    Marrese-Reading, Colleen; Markusic, Tom; Polzin, Kurt; Knowles, Timothy; Mueller, Juergen

    2005-01-01

    A bismuth feed system was developed for the VHITAL Program to deliver 8-12 mg/s of bismuth vapor at a few Torr to the VHITAL-160. A carbon vaporizer developed to control vapor flow rates to the thruster.

  1. [Airborne fungal community composition in indoor environments in Beijing].

    PubMed

    Fang, Zhi-guo; Ouyang, Zhi-yun; Liu, Peng; Sun, Li; Wang, Xiao-yong

    2013-05-01

    Indoor environmental quality has significant effects on human health. It is reported that adults in China spent about 80%-90% of their time in indoor environments, and a number of physically handicapped people such as the elderly and infants stayed in the room even up to 95% of their total time. Moreover, air conditioner in indoor environments becomes more and more important in modern life, and a closed circulatory system can be formed among human body, room and air conditioner in indoor environments with an air conditioner, which can make the microbes such as bacteria, viruses and mold indoors propagate rapidly or abundantly. Therefore, studies on the microbial pollution in the air at places such as mall, classroom, office, and family home have been the research hotspots recently. In the present study, the community composition and concentration variation pattern of airborne fungi were investigated from Nov 2009 to Oct 2010 in 31 family homes with children in Beijing. Results showed that 24 generas of airborne fungi in family homes were identified from 225 isolates. The most common fungi were Penicillium, Cladosporium, Aspergillus, Alternaria and Phoma. The frequency of Penicillium, Cladosporium, Aspergillus, Alternaria and Monilia was much higher than those of other fungal genera in family home, and the frequency of Penicillium was more than 90%. As for the concentration percentage, airborne fungi with most high concentrations were Penicillium, Cladosporium, Aspergillus, No-sporing, and Alternaria, and totally accounted for more than 65.0%. Penicillium contributed to 32.2% of the total airborne fungi in family homes. In the 31 family homes selected, the fungal concentration in the air ranged from 62-3 498 CFU x m(-3), and the mean concentration was 837 CFU x m(-3). Seasonal variation pattern of total fungi, and Cladosporium, Aspergillus, Alternaria concentration was consistent, and the highest fungal concentration was observed in summer, followed by spring and

  2. Airborne Gamma-Spectrometry in Switzerland

    SciTech Connect

    Butterweck, Gernot; Bucher, Benno; Rybach, Ladislaus

    2008-08-07

    Airborne gamma-spectrometry is able to obtain fast radiological information over large areas. The airborne gamma-spectrometry unit deployed in Switzerland by the Swiss National Emergency Operations Centre (NEOC) consists of a Swiss army Super Puma helicopter equipped with four NaI-Detectors with a total volume of 17 liters, associated electronics and a real-time data evaluation and mapping unit developed by the Swiss Federal Institute of Technology (ETH) and the Paul Scherrer Institut (PSI). The operational readiness of the airborne gamma-spectrometry system is validated in annual exercises of one week duration. Data from 2005 and 2006 exercises are represented in maps of {sup 137}Cs activity concentration for two towns located in southern and western Switzerland. An indicator of man-made radioactivity (MMGC ratio) is demonstrated for an area with four different types of nuclear installations. The intercomparison between airborne gamma-spectrometry and ground measurements showed good agreement between both methods.

  3. Principles for Sampling Airborne Radioactivity from Stacks

    SciTech Connect

    Glissmeyer, John A.

    2010-10-18

    This book chapter describes the special processes involved in sampling the airborne effluents from nuclear faciities. The title of the book is Radioactive Air Sampling Methods. The abstract for this chapter was cleared as PNNL-SA-45941.

  4. SOURCES OF HUMAN EXPOSURE TO AIRBORNE PAH

    EPA Science Inventory

    Personal exposures to airborne particulate polycyclic aromatic hydrocarbons (PAHs) were studied in several populations in the US, Japan, and Czech Republic. Personal exposure monitors, developed for human exposure biomonitoring studies were used to collect fine particles (<_ 1....

  5. Mapping of airborne Doppler radar data

    SciTech Connect

    Lee, W.; Dodge, P.; Marks, F.D. Jr.; Hildebrand, P.H. NOAA, Miami, FL )

    1994-04-01

    Two sets of equations are derived to (1) map airborne Doppler radar data from an aircraft-relative coordinate system to an earth-relative coordinate system, and (2) remove the platform motion from the observed Doppler velocities. These equations can be applied to data collected by the National Oceanic and Atmospheric Administration WP-3D system, the National Center for Atmospheric Research Electra Doppler Radar (ELDORA) system, and other airborne radar systems.

  6. Application of 2D-GCMS reveals many industrial chemicals in airborne particulate matter

    NASA Astrophysics Data System (ADS)

    Alam, Mohammed S.; West, Charles E.; Scarlett, Alan G.; Rowland, Steven J.; Harrison, Roy M.

    2013-02-01

    Samples of airborne particulate matter (PM2.5) have been collected in Birmingham, UK and extracted with dichloromethane prior to analysis by two-dimensional GC separation and TOFMS analysis. Identification of compounds using the NIST spectral library has revealed a remarkable diversity of compounds, some of which have not been previously reported in airborne analyses. Groups of compounds identified in this study include a large number of oxygenated VOC including linear and branched compounds, substituted aromatic compounds and alicyclic compounds, oxygenated polycyclic aromatic and alicyclic compounds, organic nitrogen compounds, branched chain VOC and substituted aromatic VOC, phthalates, organo-phosphates and organo-sulphate compounds. Many of the compounds identified are mass production chemicals, which due to their semi-volatility enter the atmosphere and subsequently partition onto pre-existing aerosol. Their contribution to the toxicity of airborne particulate matter is currently unknown but might be significant. The diverse industrial uses and potential sources of the identified compounds are reported.

  7. Overview of the Use of ATHENA for Thermal-Hydraulic Analysis of Systems with Lead-Bismuth Coolant

    SciTech Connect

    Davis, Cliff Bybee; Shieh, Arthur Shan Luk

    2000-04-01

    The INEEL and MIT are investigating the suitability of lead-bismuth cooled fast reactor for producing low-cost electricity as well as for actinide burning. This paper is concerned with the general area of thermal-hydraulics of lead-bismuth cooled reactors. The ATHENA code is being used in the thermal-hydraulic design and analysis of lead-bismuth cooled reactors. The ATHENA code was reviewed to determine its applicability for simulating lead-bismuth cooled reactors. Two modifications were made to the code as a result of this review. Specifically, a correlation to represent heat transfer from rod bundles to a liquid metal and a void correlation based on data taken in a mixture of lead-bismuth and steam were added the code. The paper also summarizes the analytical work that is being performed with the code and plans for future analytical work.

  8. Overview of the use of ATHENA for thermal-hydraulic analysis of systems with lead-bismuth coolant

    SciTech Connect

    C. B. Davis; A. S. Shieh

    2000-04-02

    The INEEL and MIT are investigating the suitability of lead-bismuth cooled fast reactor for producing low-cost electricity as well as for actinide burning. This paper is concerned with the general area of thermal-hydraulics of lead-bismuth cooled reactors. The ATHENA code is being used in the thermal-hydraulic design and analysis of lead-bismuth cooled reactors. The ATHENA code was reviewed to determine its applicability for simulating lead-bismuth cooled reactors. Two modifications were made to the code as a result of this review. Specifically, a correlation to represent heat transfer from rod bundles to a liquid metal and a void correlation based on data taken in a mixture of lead-bismuth and steam were added the code. The paper also summarizes the analytical work that is being performed with the code and plans for future analytical work.

  9. A Synergistic Approach to Atmospheric Compensation of Neon's Airborne Hyperspectral Imagery Utilizing an Airborne Solar Spectral Irradiance Radiometer

    NASA Astrophysics Data System (ADS)

    Wright, L.; Karpowicz, B. M.; Kindel, B. C.; Schmidt, S.; Leisso, N.; Kampe, T. U.; Pilewskie, P.

    2014-12-01

    A wide variety of critical information regarding bioclimate, biodiversity, and biogeochemistry is embedded in airborne hyperspectral imagery. Most, if not all of the primary signal relies upon first deriving the surface reflectance of land cover and vegetation from measured hyperspectral radiance. This places stringent requirements on terrain, and atmospheric compensation algorithms to accurately derive surface reflectance properties. An observatory designed to measure bioclimate, biodiversity, and biogeochemistry variables from surface reflectance must take great care in developing an approach which chooses algorithms with the highest accuracy, along with providing those algorithms with data necessary to describe the physical mechanisms that affect the measured at sensor radiance. The Airborne Observation Platform (AOP) part of the National Ecological Observatory Network (NEON) is developing such an approach. NEON is a continental-scale ecological observation platform designed to collect and disseminate data to enable the understanding and forecasting of the impacts of climate change, land use change, and invasive species on ecology. The instrumentation package used by the AOP includes a visible and shortwave infrared hyperspectral imager, waveform LiDAR, and high resolution (RGB) digital camera. In addition to airborne measurements, ground-based CIMEL sun photometers will be used to help characterize atmospheric aerosol loading, and ground validation measurements with field spectrometers will be made at select NEON sites. While the core instrumentation package provides critical information to derive surface reflectance of land surfaces and vegetation, the addition of a Solar Spectral Irradiance Radiometer (SSIR) is being investigated as an additional source of data to help identify and characterize atmospheric aerosol, and cloud contributions contributions to the radiance measured by the hyperspectral imager. The addition of the SSIR provides the opportunity to

  10. Promotional Effects of Bismuth on the Formation of Platinum-Bismuth Nanowires Network and the Electrocatalytic Activity toward Ethanol Oxidation

    SciTech Connect

    Du, W.; Su, D.; Wang, Q.; Frenkel, A.I.; Teng, X.

    2011-01-11

    Electrocatalytic activities of Pt and their alloys toward small organic molecules oxidation are highly dependent on their morphology, chemical composition, and electronic structure. Here, we report the synthesis of dendrite-like Pt{sub 95}Bi{sub 5}, Pt{sub 83}Bi{sub 17}, and Pt{sub 76}Bi{sub 24} nanowires network with a high aspect ratio (up to 68). The electronic structure and heterogeneous crystalline structure have been studied using combined techniques, including aberration-corrected scanning transmission electron microscopy (STEM) and X-ray absorption near-edge structure (XANES) spectroscopy. Bismuth-oriented attachment growth mechanism has been proposed for the anisotropic growth of Pt/Bi. The electrochemical activities of Pt/Bi nanowires network toward ethanol oxidations have been tested. In particular, the as-made Pt{sub 95}Bi{sub 5} appears to have superior activity toward ethanol oxidation in comparison with the commercial Pt/C catalyst. The reported promotional effect of Bi on the formation of Pt/Bi and electrochemical activities will be important to design effective catalysts for ethanol fuel cell application.

  11. Promotional Effects of Bismuth on the Formation of Platinum-Bismuth Nanowires Network and the Electrocatalytic Activity toward Ethanol Oxidation

    SciTech Connect

    X Teng; W Du; D Su; Q Wang; A Frenkel

    2011-12-31

    Electrocatalytic activities of Pt and their alloys toward small organic molecules oxidation are highly dependent on their morphology, chemical composition, and electronic structure. Here, we report the synthesis of dendrite-like Pt{sub 95}Bi{sub 5}, Pt{sub 83}Bi{sub 17}, and Pt{sub 76}Bi{sub 24} nanowires network with a high aspect ratio (up to 68). The electronic structure and heterogeneous crystalline structure have been studied using combined techniques, including aberration-corrected scanning transmission electron microscopy (STEM) and X-ray absorption near-edge structure (XANES) spectroscopy. Bismuth-oriented attachment growth mechanism has been proposed for the anisotropic growth of Pt/Bi. The electrochemical activities of Pt/Bi nanowires network toward ethanol oxidations have been tested. In particular, the as-made Pt{sub 95}Bi{sub 5} appears to have superior activity toward ethanol oxidation in comparison with the commercial Pt/C catalyst. The reported promotional effect of Bi on the formation of Pt/Bi and electrochemical activities will be important to design effective catalysts for ethanol fuel cell application.

  12. Challenges and opportunities of airborne metagenomics.

    PubMed

    Behzad, Hayedeh; Gojobori, Takashi; Mineta, Katsuhiko

    2015-05-01

    Recent metagenomic studies of environments, such as marine and soil, have significantly enhanced our understanding of the diverse microbial communities living in these habitats and their essential roles in sustaining vast ecosystems. The increase in the number of publications related to soil and marine metagenomics is in sharp contrast to those of air, yet airborne microbes are thought to have significant impacts on many aspects of our lives from their potential roles in atmospheric events such as cloud formation, precipitation, and atmospheric chemistry to their major impact on human health. In this review, we will discuss the current progress in airborne metagenomics, with a special focus on exploring the challenges and opportunities of undertaking such studies. The main challenges of conducting metagenomic studies of airborne microbes are as follows: 1) Low density of microorganisms in the air, 2) efficient retrieval of microorganisms from the air, 3) variability in airborne microbial community composition, 4) the lack of standardized protocols and methodologies, and 5) DNA sequencing and bioinformatics-related challenges. Overcoming these challenges could provide the groundwork for comprehensive analysis of airborne microbes and their potential impact on the atmosphere, global climate, and our health. Metagenomic studies offer a unique opportunity to examine viral and bacterial diversity in the air and monitor their spread locally or across the globe, including threats from pathogenic microorganisms. Airborne metagenomic studies could also lead to discoveries of novel genes and metabolic pathways relevant to meteorological and industrial applications, environmental bioremediation, and biogeochemical cycles. PMID:25953766

  13. Challenges and Opportunities of Airborne Metagenomics

    PubMed Central

    Behzad, Hayedeh; Gojobori, Takashi; Mineta, Katsuhiko

    2015-01-01

    Recent metagenomic studies of environments, such as marine and soil, have significantly enhanced our understanding of the diverse microbial communities living in these habitats and their essential roles in sustaining vast ecosystems. The increase in the number of publications related to soil and marine metagenomics is in sharp contrast to those of air, yet airborne microbes are thought to have significant impacts on many aspects of our lives from their potential roles in atmospheric events such as cloud formation, precipitation, and atmospheric chemistry to their major impact on human health. In this review, we will discuss the current progress in airborne metagenomics, with a special focus on exploring the challenges and opportunities of undertaking such studies. The main challenges of conducting metagenomic studies of airborne microbes are as follows: 1) Low density of microorganisms in the air, 2) efficient retrieval of microorganisms from the air, 3) variability in airborne microbial community composition, 4) the lack of standardized protocols and methodologies, and 5) DNA sequencing and bioinformatics-related challenges. Overcoming these challenges could provide the groundwork for comprehensive analysis of airborne microbes and their potential impact on the atmosphere, global climate, and our health. Metagenomic studies offer a unique opportunity to examine viral and bacterial diversity in the air and monitor their spread locally or across the globe, including threats from pathogenic microorganisms. Airborne metagenomic studies could also lead to discoveries of novel genes and metabolic pathways relevant to meteorological and industrial applications, environmental bioremediation, and biogeochemical cycles. PMID:25953766

  14. Bismuth Oxide Thin Films Deposited on Silicon Through Pulsed Laser Ablation, for Infrared Detectors

    NASA Astrophysics Data System (ADS)

    Condurache-Bota, Simona; Constantinescu, Catalin; Tigau, Nicolae; Praisler, Mirela

    2016-12-01

    Infrared detectors are used in many human activities, from industry to military, telecommunications, environmental studies and even medicine. Bismuth oxide thin films have proved their potential for optoelectronic applications, but their uses as infrared sensors have not been thoroughly studied so far. In this paper, pulsed laser ablation of pure bismuth targets within a controlled oxygen atmosphere is proposed for the deposition of bismuth oxide films on Si (100) substrates. Crystalline films were obtained, whose uniformity depends on the deposition conditions (number of laser pulses and the use of a radio-frequency (RF) discharge of the oxygen inside the deposition chamber). The optical analysis proved that the refractive index of the films is higher than 3 and that their optical bandgap is around 1eV, recommending them for infrared applications.

  15. Preparation of bismuth-based nanosheets by ultrasound-assisted liquid laser ablation

    NASA Astrophysics Data System (ADS)

    Escobar-Alarcón, L.; Velarde Granados, E.; Solís-Casados, D. A.; Olea-Mejía, O.; Espinosa-Pesqueira, M.; Haro-Poniatowski, E.

    2016-04-01

    The preparation of bismuth nanosheets ablating a high purity Bi target immersed in water subjected to an ultrasound wave is reported. The effect of the laser fluence used for ablation on the size and shape of the nanostructures synthesized was investigated. The obtained results reveal the formation of nanosheets with square-like shape and sizes from approximately 140-543 nm. In comparison, experiments without the ultrasound field lead to the formation of quasi-spherical nanoparticles. The nanosheets were characterized by means of transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS), UV-Vis and Raman spectroscopies. The bismuth nanosheets, as deposited, are highly crystalline, and depending on the preparation conditions, the α or β phases of Bi2O3 are obtained. UV-Vis measurements show the typical band absorption characteristic of bismuth with nanometric size. Raman spectra confirm the formation of Bi2O3 nanostructures.

  16. Molecular orbital model of optical centers in bismuth-doped glasses.

    PubMed

    Kustov, E F; Bulatov, L I; Dvoyrin, V V; Mashinsky, V M

    2009-05-15

    Spectroscopic properties of optical fibers with a bismuth-doped silicate glass core are explained on the basis of molecular orbital theory and a solution of the Schrödinger equation, which takes into account the exchange, the spin-orbital, and the glass field potential interactions of s, p, and d electron shells of bismuth with s(sigma), p(sigma), and p(pi) orbits of oxygen atoms. The approach can explain the IR luminescence properties of other optical centers formed by other atoms with the same structure of electron shells as the bismuth atom. The model of transitions based on intramolecular charge transfer between molecular orbital and metallic states is proposed. PMID:19448817

  17. Design of an Actinide Burning, Lead-Bismuth Cooled Reactor That Produces Low Cost Electricity

    SciTech Connect

    C. Davis; S. Herring; P. MacDonald; K. McCarthy; V. Shah; K. Weaver; J. Buongiorno; R. Ballinger; K. Doyoung; M. Driscoll; P. Hejzler; M. Kazimi; N. Todreas

    1999-07-01

    The purpose of this project is to investigate the suitability of lead-bismuth cooled fast reactors for producing low-cost electricity as well as for actinide burning. The goal is to identify and analyze the key technical issues in core neutronics, materials, thermal-hydraulics, fuels, and economics associated with the development of this reactor concept. The choice of lead-bismuth for the reactor coolant is an actinide burning fast reactor offers enhanced safety and reliability. The advantages of lead-bismuth over sodium as a coolant are related to the following material characteristics: chemical inertness with air and water; higher atomic number; lower vapor pressure at operating temperatures; and higher boiling temperature. Given the status of the field, it was agreed that the focus of this investigation in the first two years will be on the assessment of approaches to optimize core and plant arrangements in order to provide maximum safety and economic potential in this type of reactor.

  18. PROCESS USING BISMUTH PHOSPHATE AS A CARRIER PRECIPITATE FOR FISSION PRODUCTS AND PLUTONIUM VALUES

    DOEpatents

    Finzel, T.G.

    1959-03-10

    A process is described for separating plutonium from fission products carried therewith when plutonium in the reduced oxidation state is removed from a nitric acid solution of irradiated uranium by means of bismuth phosphate as a carrier precipitate. The bismuth phosphate carrier precipitate is dissolved by treatment with nitric acid and the plutonium therein is oxidized to the hexavalent oxidation state by means of potassium dichromate. Separation of the plutonium from the fission products is accomplished by again precipitating bismuth phosphate and removing the precipitate which now carries the fission products and a small percentage of the plutonium present. The amount of plutonium carried in this last step may be minimized by addition of sodium fluoride, so as to make the solution 0.03N in NaF, prior to the oxidation and prccipitation step.

  19. Isotopic generator for bismuth-212 and lead-212 based on radium

    DOEpatents

    Hines, J.J.; Atcher, R.W.; Friedman, A.M.

    1985-01-30

    Disclosed are method and apparatus for providing radionuclides of bismuth-212 and lead-212. Thorium-228 and carrier solution starting material is input to a radiologically contained portion of an isotopic generator system, and radium-224 is separated from thorium-228 which is retained by a strongly basic anion exchange column. The separated radium-224 is transferred to an accessible, strongly acidic cationic exchange column. The cationic column retains the radium-224, and natural radioactive decay generates bismuth-212 and lead-212. The cationic exchange column can also be separated from the contained portion of the system and utilized without the extraordinary safety measures necessary in the contained portion. Furthermore, the cationic exchange column provides over a relatively long time period the short lived lead-212 and bismuth-212 radionuclides which are useful for a variety of medical therapies.

  20. Bismuth- and lithium-loaded plastic scintillators for gamma and neutron detection

    NASA Astrophysics Data System (ADS)

    Cherepy, Nerine J.; Sanner, Robert D.; Beck, Patrick R.; Swanberg, Erik L.; Tillotson, Thomas M.; Payne, Stephen A.; Hurlbut, Charles R.

    2015-04-01

    Transparent plastic scintillators based on polyvinyltoluene (PVT) have been fabricated with high loading of bismuth carboxylates for gamma spectroscopy, and with lithium carboxylates for neutron detection. When activated with a combination of standard fluors, 2,5-diphenyloxazole (PPO) and tetraphenylbutadiene (TPB), gamma light yields with 15 wt% bismuth tripivalate of 5000 Ph/MeV are measured. A PVT plastic formulation including 30 wt% lithium pivalate and 30 wt% PPO offers both pulse shape discrimination, and a neutron capture peak at ~400 keVee. In another configuration, a bismuth-loaded PVT plastic is coated with ZnS(6Li) paint, permitting simultaneous gamma and neutron detection via pulse shape discrimination with a figure-of-merit of 3.8, while offering gamma spectroscopy with energy resolution of R(662 keV)=15%.

  1. Application of Thermodynamic Calculations to the Pyro-refining Process for Production of High Purity Bismuth

    NASA Astrophysics Data System (ADS)

    Mezbahul-Islam, Mohammad; Belanger, Frederic; Chartrand, Patrice; Jung, In-Ho; Coursol, Pascal

    2016-04-01

    The present work has been performed with the aim to optimize the existing process for the production of high purity bismuth (99.999 pct). A thermo-chemical database including most of the probable impurities of bismuth (Bi-X, X = Ag, Au, Al, Ca, Cu, Fe, Mg, Mn, Na, Ni, Pb, S, Sb, Sn, Si, Te, Zn) has been constructed to perform different thermodynamic calculations required for the refining process. Thermodynamic description for eight of the selected binaries, Bi-Ca, Cu, Mn, Ni, Pb, S, Sb, and Sn, has been given in the current paper. Using the current database, different thermodynamic calculations have been performed to explain the steps involved in the bismuth refining process.

  2. Combined excitation-emission spectroscopy of bismuth active centers in optical fibers.

    PubMed

    Firstov, S V; Khopin, V F; Bufetov, I A; Firstova, E G; Guryanov, A N; Dianov, E M

    2011-09-26

    For the first time, 3-dimensional luminescence spectra (luminescence intensity as a function of the excitation and emission wavelengths) have been obtained for bismuth-doped optical fibers of various compositions in a wide spectral range (450-1700 nm). The bismuth-doped fibers investigated have the following core compositions: SiO(2), GeO(2), Al-doped SiO(2), and P-doped SiO(2). The measurements are performed at room and liquid nitrogen temperatures. Based on the experimental results, the positions of the low-lying energy-levels of the IR bismuth active centers in SiO(2)- and GeO(2)-core fibers have been determined. Similarity of the energy-level schemes for the two core compositions has been revealed. PMID:21996896

  3. Comparative toxicities of bismuth oxybromide and titanium dioxide exposure on human skin keratinocyte cells.

    PubMed

    Gao, Xiaoya; Wang, Yawen; Peng, Shiqi; Yue, Bin; Fan, Caimei; Chen, Weiyi; Li, Xiaona

    2015-09-01

    Nano-sized bismuth oxybromide (BiOBr) particles are being considered for applications within the semiconductor industry. However, little is known about their potential impact on human health. In this study, we comparatively investigated the cytotoxicity of BiOBr and titanium dioxide (TiO2) nanoparticles (NPs) using human skin keratinocyte cell line (HaCaT) as a research model. Results indicate that lamellar-shaped BiOBr (length: 200 nm, width: 150 nm, and an average thickness: around 15 nm) has less toxic effects on cell viability and intracellular organelles than TiO2 (P25) NPs. BiOBr mainly induced late cell apoptosis, while for TiO2, both early apoptosis and late apoptosis were involved. Cell cycle arrest was found in cells on both NPs exposure, and more prominent in TiO2-treated cells. More cellular uptake was achieved after TiO2 exposure, particularly at 10 μg mL(-1), presence of TiO2 resulted in more than 2-fold increase in cellular granularity compared with BiOBr. Furthermore, TiO2 had a high potential to generate intracellular reactive oxygen species (ROS) in cells, where a 2.7-fold increase in TiO2 group and 2.0-fold increase in BiOBr group at the same concentration of 25 μg mL(-1). Higher cellular uptake and ROS stimulation should contribute to the more hazards of TiO2 than BiOBr NPs. This knowledge is a crucial component in the environmental and human hazard assessment of BiOBr and TiO2 NPs. PMID:25917605

  4. CONCENTRATION AND DECONTAMINATION OF SOLUTIONS CONTAINING PLUTONIUM VALUES BY BISMUTH PHOSPHATE CARRIER PRECIPITATION METHODS

    DOEpatents

    Seaborg, G.T.; Thompson, S.G.

    1960-08-23

    A process is given for isolating plutonium present in the tetravalent state in an aqueous solution together with fission products. First, the plutonium and fission products are coprecipitated on a bismuth phosphate carrier. The precipitate obtained is dissolved, and the plutonium in the solution is oxidized to the hexavalent state (with ceric nitrate, potassium dichromate, Pb/ sub 3/O/sub 4/, sodium bismuthate and/or potassium dichromate). Thereafter a carrier for fission products is added (bismuth phosphate, lanthanum fluoride, ceric phosphate, bismuth oxalate, thorium iodate, or thorium oxalate), and the fission-product precipitation can be repeated with one other of these carriers. After removal of the fission-product-containing precipitate or precipitates. the plutonium in the supernatant is reduced to the tetravalent state (with sulfur dioxide, hydrogen peroxide. or sodium nitrate), and a carrier for tetravalent plutonium is added (lanthanum fluoride, lanthanum hydroxide, lanthanum phosphate, ceric phosphate, thorium iodate, thorium oxalate, bismuth oxalate, or niobium pentoxide). The plutonium-containing precipitate is then dissolved in a relatively small volume of liquid so as to obtain a concentrated solution. Prior to dissolution, the bismuth phosphate precipitates first formed can be metathesized with a mixture of sodium hydroxide and potassium carbonate and plutonium-containing lanthanum fluorides with alkali-metal hydroxide. In the solutions formed from a plutonium-containing lanthanum fluoride carrier the plutonium can be selectively precipitated with a peroxide after the pH was adjusted preferably to a value of between 1 and 2. Various combinations of second, third, and fourth carriers are discussed.

  5. Bismuth Passivation Technique for High-Resolution X-Ray Detectors

    NASA Technical Reports Server (NTRS)

    Chervenak, James; Hess, Larry

    2013-01-01

    The Athena-plus team requires X-ray sensors with energy resolution of better than one part in 3,000 at 6 keV X-rays. While bismuth is an excellent material for high X-ray stopping power and low heat capacity (for large signal when an X-ray is stopped by the absorber), oxidation of the bismuth surface can lead to electron traps and other effects that degrade the energy resolution. Bismuth oxide reduction and nitride passivation techniques analogous to those used in indium passivation are being applied in a new technique. The technique will enable improved energy resolution and resistance to aging in bismuth-absorber-coupled X-ray sensors. Elemental bismuth is lithographically integrated into X-ray detector circuits. It encounters several steps where the Bi oxidizes. The technology discussed here will remove oxide from the surface of the Bi and replace it with nitridized surface. Removal of the native oxide and passivating to prevent the growth of the oxide will improve detector performance and insulate the detector against future degradation from oxide growth. Placing the Bi coated sensor in a vacuum system, a reduction chemistry in a plasma (nitrogen/hydrogen (N2/H2) + argon) is used to remove the oxide and promote nitridization of the cleaned Bi surface. Once passivated, the Bi will perform as a better X-ray thermalizer since energy will not be trapped in the bismuth oxides on the surface. A simple additional step, which can be added at various stages of the current fabrication process, can then be applied to encapsulate the Bi film. After plasma passivation, the Bi can be capped with a non-diffusive layer of metal or dielectric. A non-superconducting layer is required such as tungsten or tungsten nitride (WNx).

  6. Microstructure and Mechanical Properties of Tin-Bismuth Solder Reinforced by Aluminum Borate Whiskers

    NASA Astrophysics Data System (ADS)

    Wang, Jun; Wei, Hongmei; He, Peng; Lin, Tiesong; Lu, Fengjiao

    2015-10-01

    Tin-bismuth solder has emerged as a promising lead-free alternative to tin-lead solder, especially for low-temperature packaging applications. However, the intrinsic brittleness of tin-bismuth solder alloy, aggravated by the coarse bismuth-rich phase and the thick interfacial intermetallic layer, notably limits the mechanical performance of the bonded joints. In this work, the microstructure and mechanical performance of solder joints were improved by adding 3.2 vol.% aluminum borate whiskers to the tin-bismuth solder alloy. This whisker-reinforced composite solder was fabricated through a simple process. Typically, 25- μm to 75- μm tin-bismuth particles were mixed with a small amount of aluminum borate whiskers with diameter of 0.5 μm to 1.5 μm and length of 5 μm to 15 μm. The addition of whiskers restrained the formation of coarse brittle bismuth-rich phase and decreased the lamellar spacing from 0.84 μm to 7.94 μm to the range of 0.22 μm to 1.80 μm. Moreover, the growth rate of the interfacial intermetallic layer during the remelting treatment decreased as well. The joint shear strength increased from 19.4 MPa to 24.7 MPa, and only declined by 4.9% (average, -5.9% to 15.8%) after the tenth remelting, while the shear strength of the joint without whiskers declined by 31.5% (average, 10.1-44.1%). The solder alloy was reinforced because of their high strength and high modulus and also the refinement effect on the solder alloy microstructure.

  7. Influence of bismuth on the charging ability of negative plates in lead-acid batteries

    NASA Astrophysics Data System (ADS)

    Lam, L. T.; Ceylan, H.; Haigh, N. P.; Manders, J. E.

    To examine the influence of bismuth on the charging ability of negative plates in lead-acid batteries, plates are made from three types of oxides: (i) leady oxide of high quality which contains virtually no bismuth (termed 'control oxide'); (ii) control oxide in which bismuth oxide is blended at bismuth levels from 0.01 to 0.12 wt.%; (iii) leady oxide produced from Pasminco VRLA Refined™ lead (0.05-0.06 wt.%Bi). An experimental tool—the 'conversion indicator'—is developed to assess the charging ability of the test negative plates when cycling under either zero percent state-of-charge (SoC)/full-charge or partial state-of-charge (PSoC) duty. Although the conversion indicator is not the true charging efficiency, the two parameters have a close relationship, namely, the higher the conversion indicator, the greater the charging efficiency. Little difference is found in the charging ability, irrespective of bismuth content and discharge rate, when the plates are subjected to zero percent SoC/full-charge duty; the conversion indicator lies in the range 81-84%. By contrast, there is a marked difference when the negative plates are subjected to PSoC duty, i.e. consecutive cycling through 90-60, 70-40, 80-40 and 90-40% SoC windows. Up to 0.06 wt.%Bi improves the charging ability, especially with a low and narrow PSoC window (40-70% SoC) of the type that will be experienced in 42 V powernet automobile and hybrid electric duties. To maximize this beneficial effect, bismuth must be distributed uniformly in the plates. This is best achieved by using VRLA Refined™ lead for oxide production.

  8. The impact of fireworks on airborne particles

    NASA Astrophysics Data System (ADS)

    Vecchi, Roberta; Bernardoni, Vera; Cricchio, Diana; D'Alessandro, Alessandra; Fermo, Paola; Lucarelli, Franco; Nava, Silvia; Piazzalunga, Andrea; Valli, Gianluigi

    Fireworks are one of the most unusual sources of pollution in atmosphere; although transient, these pollution episodes are responsible for high concentrations of particles (especially metals and organic compounds) and gases. In this paper, results of a study on chemical-physical properties of airborne particles (elements, ions, organic and elemental carbon and particles size distributions) collected during a fireworks episode in Milan (Italy) are reported. Elements typically emitted during pyrotechnic displays increased in 1 h as follows: Sr (120 times), Mg (22 times), Ba (12 times), K (11 times), and Cu (6 times). In our case study, Sr was recognised as the best fireworks tracer because its concentration was very high during the event and lower than, or comparable with, minimum detection limits during other time intervals, suggesting that it was mainly due to pyrotechnic displays. In addition, particles number concentrations increased significantly during the episode (up to 6.7 times in 1 h for the 0.5< d<1 μm size bin). Contributions (e.g. Cu, elemental carbon and nitrogen oxides) to air pollution due to the large traffic volume registered during the same night were also singled out. The original application of Positive Matrix Factorisation and Multiple Linear Regression allowed, as far as we know, here for the first time, the quantification of the fireworks contribution to atmospheric particulate matter (PM) and the resolution of their chemical profile. The contribution of fireworks to the local environment in terms of PM 10 mass, elements and chemical components was assessed with 4-h time resolution. PM 10 mass apportioned by fireworks was up to 33.6 μg m -3 (about 50% of the total PM 10 mass). Major contributors were elemental and organic carbon (2.8 and 8.1 μg m -3, respectively) as well as metals like Mg, K, Sr, Ba, and Cu (0.4, 0.7, 0.07, 0.1, and 0.1 μg m -3, respectively).

  9. Equilibrium distribution of lanthanum, neodymium, and thorium between lithium chloride melt and liquid bismuth

    NASA Astrophysics Data System (ADS)

    Zagnit'ko, A. V.; Ignat'ev, V. V.

    2013-04-01

    The distribution of lanthanum, neodymium, and thorium between a lithium chloride melt and liquid bismuth with additions of lithium as a reducing agent are investigated at 650°C. Equilibrium values of their distribution constants are measured. It is shown that in contrast to neodymium and lanthanum, thorium cannot be extracted from bismuth into lithium chloride. This allows us to propose an efficient scheme for separating lanthanides and thorium in a system for the extraction of fuel salts in molten-salt nuclear reactors.

  10. Giant Effect of Uniaxial Pressure on Magnetic Domain Populations in Multiferroic Bismuth Ferrite

    NASA Astrophysics Data System (ADS)

    Ramazanoglu, M.; Ratcliff, W., II; Yi, H. T.; Sirenko, A. A.; Cheong, S.-W.; Kiryukhin, V.

    2011-08-01

    Neutron diffraction is used to show that small (˜7MPa, or 70 bar) uniaxial pressure produces significant changes in the populations of magnetic domains in a single crystal of 2% Nd-doped bismuth ferrite. The magnetic easy plane of the domains converted by the pressure is rotated 60° relative to its original position. These results demonstrate extreme sensitivity of the magnetic properties of multiferroic bismuth ferrite to tiny (less than 10-4) elastic strain, as well as weakness of the forces pinning the domain walls between the cycloidal magnetic domains in this material.

  11. Fabrication of Nanovoid-Imbedded Bismuth Telluride with Low Dimensional System

    NASA Technical Reports Server (NTRS)

    Chu, Sang-Hyon (Inventor); Choi, Sang H. (Inventor); Kim, Jae-Woo (Inventor); Park, Yeonjoon (Inventor); Elliott, James R. (Inventor); King, Glen C. (Inventor); Stoakley, Diane M. (Inventor)

    2013-01-01

    A new fabrication method for nanovoids-imbedded bismuth telluride (Bi--Te) material with low dimensional (quantum-dots, quantum-wires, or quantum-wells) structure was conceived during the development of advanced thermoelectric (TE) materials. Bismuth telluride is currently the best-known candidate material for solid-state TE cooling devices because it possesses the highest TE figure of merit at room temperature. The innovative process described here allows nanometer-scale voids to be incorporated in Bi--Te material. The final nanovoid structure such as void size, size distribution, void location, etc. can be also controlled under various process conditions.

  12. Decay of photoinduced oscillations of the optical reflection coefficient of bismuth

    SciTech Connect

    Semenov, A. L.

    2013-07-15

    A model describing the decay of photoinduced oscillations of the optical reflection coefficient R of bismuth is constructed, taking the crystal lattice anharmonicity into account. The decay time of oscillations of R is calculated as a function of the energy density of a laser pulse. The results of calculations explain the experimental data on the anomalously strong decay of oscillations of the optical reflection coefficient of bismuth (the decay time decreases by more than an order of magnitude with an increase in the laser pulse energy density from 0 to 4 mJ/cm{sup 2})

  13. Numerical study: Iron corrosion-resistance in lead-bismuth eutectic coolant by molecular dynamics method

    SciTech Connect

    Arkundato, Artoto; Su'ud, Zaki; Abdullah, Mikrajuddin; Widayani,; Celino, Massimo

    2012-06-06

    In this present work, we report numerical results of iron (cladding) corrosion study in interaction with lead-bismuth eutectic coolant of advanced nuclear reactors. The goal of this work is to study how the oxygen can be used to reduce the corrosion rate of cladding. The molecular dynamics method was applied to simulate corrosion process. By evaluating the diffusion coefficients, RDF functions, MSD curves of the iron and also observed the crystal structure of iron before and after oxygen injection to the coolant then we concluded that a significant and effective reduction can be achieved by issuing about 2% number of oxygen atoms to lead-bismuth eutectic coolant.

  14. Bismuth germanate's role in the new revolution in gamma-ray spectroscopy

    SciTech Connect

    Johnson, N.R.; Baktash, C.; Lee, I.Y.

    1983-01-01

    Some of the considerations on how to effectively incorporate bismuth germanate into complex detection systems are covered, and some of these new systems now in operation or under construction are discussed. Significant achievements in gamma ray spectroscopy are reviewed as well as some recent results based on data taken with coincidence arrays of germanium detectors and Compton-suppression spectrometers. Then the first impact of bismuth germanate detectors on our understanding of the properties of nuclei that have high energy and very high angular momentum states are addressed. (LEW)

  15. Airborne detection of asperities: Linking aerogravimetry surveys and earthquake studies

    NASA Astrophysics Data System (ADS)

    Meyer, U.; Boedecker, G.

    2003-04-01

    , collaborative research center SFB-267, Servicio Aerofotogrametrico and the Instituto Geografico Militar in Santiago de Chile performed an airborne survey offshore and onshore Chile covering the area form 37° S to 39° S . One of the major aims of the survey was to undertake the first systematic attempt to identify asperity structures using a LaCoste &Romberg airborne gravity meter in combination with a 3-D strap-down gravity meter system. First results of this airborne survey will be presented. The ability to map and identify asperities will be largely enhanced by the future application of gravimetric gradiometer systems. It will be shown that gradiometers already have the proper detection level to answer most of the questions raised. If gravimetric surveys will be able to put a finger on asperity structures, this would be most a valuable contribution in earthquake studies and risk assessment. Literature: Wells, R. E., Blakeley, R. J., Sugiyama, Y. (2000): Forearc Basins and Co-Seismic Slip in Great Subduction Zone Earthquakes AGU Meeting S12D02, Abstract, Session: S12D, Subduction Zone Structure and Megathrust Earthquakes II

  16. Pulsed Doppler lidar airborne scanner

    NASA Technical Reports Server (NTRS)

    Dimarzio, C. A.; Mcvicker, D. B.; Morrow, C. E.; Negus, C. C.

    1985-01-01

    This report covers the work accomplished during the reporting period on Pulsed Doppler Lidar Airborne Scanner and describes plans for the next reporting period. The objectives during the current phase of the contract are divided into four phases. Phase 1 includes ground testing of the system and analysis of data from the 1981 Severe Storms Test Flights. Phase 2 consists of preflight preparation and planning for the 1983 flight series. The flight test itself will be performed during Phase 3, and Phase 4 consists of post-flight analysis and operation of the system after that flight test. The range profile from five samples taken during Flight 10, around 1700 Z is given. The lowest curve is taken from data collected upwind of Mt. Shasta at about 10,000 feet of altitude, in a clear atmosphere, where no signals were observed. It thus is a good representation of the noise level as a function of range. The next curve was taken downwind of the mountain, and shows evidence of atmospheric returns. There is some question as to whether the data are valid at all ranges, or some ranges are contaminated by the others.

  17. Pulsed Doppler lidar airborne scanner

    NASA Astrophysics Data System (ADS)

    Dimarzio, C. A.; McVicker, D. B.; Morrow, C. E.; Negus, C. C.

    1985-10-01

    This report covers the work accomplished during the reporting period on Pulsed Doppler Lidar Airborne Scanner and describes plans for the next reporting period. The objectives during the current phase of the contract are divided into four phases. Phase 1 includes ground testing of the system and analysis of data from the 1981 Severe Storms Test Flights. Phase 2 consists of preflight preparation and planning for the 1983 flight series. The flight test itself will be performed during Phase 3, and Phase 4 consists of post-flight analysis and operation of the system after that flight test. The range profile from five samples taken during Flight 10, around 1700 Z is given. The lowest curve is taken from data collected upwind of Mt. Shasta at about 10,000 feet of altitude, in a clear atmosphere, where no signals were observed. It thus is a good representation of the noise level as a function of range. The next curve was taken downwind of the mountain, and shows evidence of atmospheric returns. There is some question as to whether the data are valid at all ranges, or some ranges are contaminated by the others.

  18. Medicinal smoke reduces airborne bacteria.

    PubMed

    Nautiyal, Chandra Shekhar; Chauhan, Puneet Singh; Nene, Yeshwant Laxman

    2007-12-01

    This study represents a comprehensive analysis and scientific validation of our ancient knowledge about the effect of ethnopharmacological aspects of natural products' smoke for therapy and health care on airborne bacterial composition and dynamics, using the Biolog microplate panels and Microlog database. We have observed that 1h treatment of medicinal smoke emanated by burning wood and a mixture of odoriferous and medicinal herbs (havan sámagri=material used in oblation to fire all over India), on aerial bacterial population caused over 94% reduction of bacterial counts by 60 min and the ability of the smoke to purify or disinfect the air and to make the environment cleaner was maintained up to 24h in the closed room. Absence of pathogenic bacteria Corynebacterium urealyticum, Curtobacterium flaccumfaciens, Enterobacter aerogenes (Klebsiella mobilis), Kocuria rosea, Pseudomonas syringae pv. persicae, Staphylococcus lentus, and Xanthomonas campestris pv. tardicrescens in the open room even after 30 days is indicative of the bactericidal potential of the medicinal smoke treatment. We have demonstrated that using medicinal smoke it is possible to completely eliminate diverse plant and human pathogenic bacteria of the air within confined space. PMID:17913417

  19. Visualizing Airborne and Satellite Imagery

    NASA Technical Reports Server (NTRS)

    Bierwirth, Victoria A.

    2011-01-01

    Remote sensing is a process able to provide information about Earth to better understand Earth's processes and assist in monitoring Earth's resources. The Cloud Absorption Radiometer (CAR) is one remote sensing instrument dedicated to the cause of collecting data on anthropogenic influences on Earth as well as assisting scientists in understanding land-surface and atmospheric interactions. Landsat is a satellite program dedicated to collecting repetitive coverage of the continental Earth surfaces in seven regions of the electromagnetic spectrum. Combining these two aircraft and satellite remote sensing instruments will provide a detailed and comprehensive data collection able to provide influential information and improve predictions of changes in the future. This project acquired, interpreted, and created composite images from satellite data acquired from Landsat 4-5 Thematic Mapper (TM) and Landsat 7 Enhanced Thematic Mapper plus (ETM+). Landsat images were processed for areas covered by CAR during the Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCT AS), Cloud and Land Surface Interaction Campaign (CLASIC), Intercontinental Chemical Transport Experiment-Phase B (INTEXB), and Southern African Regional Science Initiative (SAFARI) 2000 missions. The acquisition of Landsat data will provide supplemental information to assist in visualizing and interpreting airborne and satellite imagery.

  20. Planar electrostatic gradiometer for airborne geodesy

    NASA Astrophysics Data System (ADS)

    Foulon, B.; Christophe, B.; Lebat, V.; Boulanger, D.

    2011-12-01

    The knowledge of the gravity field of the Earth has been considerably improved for the last decades, thanks to satellites, in particular, both for gravity measurements and positioning. Gravity, and especially gravity gradiometry data are then of great interest to the study of the structure of the continental margins. Space gravity measurements, in particular with the GOCE satellite in orbit since 2009, provide an absolute gravity reference and should contribute to estimate the systematic effects that would affect the surface datasets. But the spatial resolution of those data essentially addresses the large and medium wavelengths of the field (down to a resolution of 90km) and it is therefore essential to complete them at the shorter wavelengths in particular in the littoral area. To this aim, gravity gradiometry systems may be particularly suitable by covering the land/sea transition zone with a uniform precision, and a spatial resolution higher than from gravimetry. The GREMLIT instrument is taking advantage of technologies, formerly developed by ONERA for the GRACE and GOCE space missions, by adapting them to an airborne environment, using a planar configuration for the gradiometer and designing and building a dedicated stabilized platform controlled by the common mode outputs of the instrument itself similarly to the drag free control of the GOCE satellite. The mains interests of the planar configuration are: - its definition, optimized for levitation in the Earth's gravity field ; - its intrinsic linearity, which minimizes the aliasing due to high frequency vibrations or motions generated outside the measurement bandwidth ; - its compactness, ensuring an excellent dimensional stability, a better thermal homogeneity and making the realization of the decoupling platform easier. The performance objective is 0.1 Eötvös. This lowered performance level with respect to a one hundred times better GOCE-type instrument, takes into account the difficulty of measurements

  1. Magnetoelectric Effect in Ceramics Based on Bismuth Ferrite.

    PubMed

    Jartych, Elżbieta; Pikula, Tomasz; Kowal, Karol; Dzik, Jolanta; Guzdek, Piotr; Czekaj, Dionizy

    2016-12-01

    Solid-state sintering method was used to prepare ceramic materials based on bismuth ferrite, i.e., (BiFeO3)1 - x -(BaTiO3) x and Bi1 - x Nd x FeO3 solid solutions and the Aurivillius Bi5Ti3FeO15 compound. The structure of the materials was examined using X-ray diffraction, and the Rietveld method was applied to phase analysis and structure refinement. Magnetoelectric coupling was registered in all the materials using dynamic lock-in technique. The highest value of magnetoelectric coupling coefficient α ME was obtained for the Bi5Ti3FeO15 compound (α ME ~ 10 mVcm(-1) Oe(-1)). In the case of (BiFeO3)1 - x -(BaTiO3) x and Bi1 - x Nd x FeO3 solid solutions, the maximum α ME is of the order of 1 and 2.7 mVcm(-1) Oe(-1), respectively. The magnitude of magnetoelectric coupling is accompanied with structural transformation in the studied solid solutions. The relatively high magnetoelectric effect in the Aurivillius Bi5Ti3FeO15 compound is surprising, especially since the material is paramagnetic at room temperature. When the materials were subjected to a preliminary electrical poling, the magnitude of the magnetoelectric coupling increased 2-3 times. PMID:27129686

  2. Photocatalytic activities of various pentavalent bismuthates under visible light irradiation

    SciTech Connect

    Takei, Takahiro; Haramoto, Rie; Dong, Qiang; Kumada, Nobuhiro; Yonesaki, Yoshinori; Kinomura, Nobukazu; Mano, Takayuki; Nishimoto, Shunsuke; Kameshima, Yoshikazu; Miyake, Michihiro

    2011-08-15

    LiBiO{sub 3}, NaBiO{sub 3}, MgBi{sub 2}O{sub 6}, KBiO{sub 3}, ZnBi{sub 2}O{sub 6}, SrBi{sub 2}O{sub 6}, AgBiO{sub 3}, BaBi{sub 2}O{sub 6} and PbBi{sub 2}O{sub 6} were synthesized by various processes such as hydrothermal treatment, heating and so on. These materials were examined for their photocatalytic activities in the decolorization of methylene blue and decomposition of phenol under visible light irradiation. For methylene blue decolorization, the presence of KBiO{sub 3} resulted in complete decoloration within 5 min. For phenol decomposition, NaBiO{sub 3} showed the highest activity, while LiBiO{sub 3}, SrBi{sub 2}O{sub 6} and BaBi{sub 2}O{sub 6} possessed almost comparable decomposition rates. Their decomposition rates were apparently higher than that by anatase (P25) under UV irradiation. - Graphical abstract: Nine pentavalent bismuthates were synthesized and were examined for their photocatalytic activities by decomposition of phenol under visible light irradiation. NaBiO{sub 3}, LiBiO{sub 3}, SrBi{sub 2}O{sub 6} and BaBi{sub 2}O{sub 6} indicated faster decomposition rate than that of anatase (P25) under UV-vis light irradiation. Highlights: > KBiO{sub 3} decolorize methylene blue aqueous solution immediately within 5 min. > NaBiO{sub 3}, LiBiO{sub 3}, SrBi{sub 2}O{sub 6} and BaBi{sub 2}O{sub 6} indicated high decomposition rate of phenol. > The d electron of Zn, Ag and Pb form broad conduction band. > The broad conduction band poses to diminish photocatalytic activity.

  3. An Inexpensive Bismuth-Petrolatum Dressing for Treatment of Burns

    PubMed Central

    Chattopadhyay, Arhana; Chang, Kathleen; Nguyen, Khoa; Galvez, Michael G.; Legrand, Anais; Davis, Christopher; McGoldrick, Rory; Long, Chao; Pham, Hung

    2016-01-01

    Background: Xeroform remains the current standard for treating superficial partial-thickness burns but can be prohibitively expensive in developing countries with prevalent burn injuries. This study (1) describes the production of an alternative low-cost dressing and (2) compares the alternative dressing and Xeroform using the metrics of cost-effectiveness, antimicrobial activity, and biocompatibility in vitro, and wound healing in vivo. Methods: To produce the alternative dressing, 3% bismuth tribromophenate powder was combined with petroleum jelly by hand and applied to Kerlix gauze. To assess cost-effectiveness, the unit costs of Xeroform and components of the alternative dressing were compared. To assess antimicrobial properties, the dressings were placed on agar plated with Escherichia coli and the Kirby-Bauer assay performed. To assess biocompatibility, the dressings were incubated with human dermal fibroblasts and cells stained with methylene blue. To assess in vivo wound healing, dressings were applied to excisional wounds on rats and the rate of re-epithelialization calculated. Results: The alternative dressing costs 34% of the least expensive brand of Xeroform. Antimicrobial assays showed that both dressings had similar bacteriostatic effects. Biocompatibility assays showed that there was no statistical difference (P < 0.05) in the cytotoxicity of Xeroform, alternative dressing, and Kerlix gauze. Finally, the in vivo healing model showed no statistical difference (P < 0.05) in mean re-epithelialization time between Xeroform (13.0 ± 1.6 days) and alternative dressing (13.5 ± 1.0 days). Conclusions: Xeroform is biocompatible, reduces infection, and enhances healing of burn wounds by preventing desiccation and mechanical trauma. Handmade petrolatum gauze may be a low-cost replacement for Xeroform. Future studies will focus on clinical trials in burn units. PMID:27482485

  4. Microwave-hydrothermal synthesis of perovskite bismuth ferrite nanoparticles

    SciTech Connect

    Biasotto, G.; Simoes, A.Z.; Foschini, C.R.; Zaghete, M.A.; Varela, J.A.; Longo, E.

    2011-12-15

    Highlights: Black-Right-Pointing-Pointer BiFeO{sub 3} (BFO) nanoparticles were grown by hydrothermal microwave method (HTMW). Black-Right-Pointing-Pointer The soaking time is effective in improving phase formation. Black-Right-Pointing-Pointer Rietveld refinement reveals an orthorhombic structure. Black-Right-Pointing-Pointer The observed magnetism of the BFO crystallites is a consequence of particle size. Black-Right-Pointing-Pointer The HTMW is a genuine technique for low temperatures and short times of synthesis. -- Abstract: Hydrothermal microwave method (HTMW) was used to synthesize crystalline bismuth ferrite (BiFeO{sub 3}) nanoparticles (BFO) in the temperature of 180 Degree-Sign C with times ranging from 5 min to 1 h. BFO nanoparticles were characterized by means of X-ray analyses, FT-IR, Raman spectroscopy, TG-DTA and FE-SEM. X-ray diffraction results indicated that longer soaking time was benefit to refraining the formation of any impurity phases and growing BFO crystallites into almost single-phase perovskites. Typical FT-IR spectra for BFO nanoparticles presented well defined bands, indicating a substantial short-range order in the system. TG-DTA analyses confirmed the presence of lattice OH{sup -} groups, commonly found in materials obtained by HTMW process. Compared with the conventional solid-state reaction process, submicron BFO crystallites with better homogeneity could be produced at the temperature as low as 180 Degree-Sign C. These results show that the HTMW synthesis route is rapid, cost effective, and could be used as an alternative to obtain BFO nanoparticles in the temperature of 180 Degree-Sign C for 1 h.

  5. New insight on bismuth cuprates with incommensurate modulated structures.

    PubMed

    Mironov, Andrei V; Petříček, Vaclav; Khasanova, Nellie R; Antipov, Evgeny V

    2016-06-01

    The incommensurate modulated crystal structure of Bi2.27Sr1.73CuO6 + δ (2201) phase [a = 5.3874 (5), b = 5.3869 (4), c = 24.579 (3) Å; β = 90.01 (1)°, q = 0.2105 (3)a(*) + 0.538 (4)c(*), Z = 4, the (3 + 1)-dimensional monoclinic A2/a(α0γ) group] has been refined with R = 0.041, wR = 0.052 from X-ray single-crystal data including up to third-order satellite reflections. The same structure has also been considered as incommensurate composite with a2 = 2.437, b2 = 5.387, c2 = 24.614, β2 = 93.06, q2 = 0.4524a2(*)-0.243c2(*) and the (3 + 1)-dimensional A2/m(α0γ)0s group for the second component. Both approaches give quite similar results. The structure possesses oxygen disorder in the oxygen-rich region of the BiO layer. An extra O atom is determined in the bridging position shifted ∼ 0.6 Å from BiO towards the SrO layer. Its presence is the cause of the tremendous increase of the bismuth U(11) atomic displacement parameter in ∼ 20% of the unit cells (t = -0.05-0.15). Vacancies are determined in the oxygen site of the SrO layer, which may result in the oxygen content variation with annealing at different oxygen pressures. The total refined oxygen content 6.18 (1) corresponds to the results of chemical analysis. PMID:27240771

  6. Electrical properties of niobium doped barium bismuth-titanate ceramics

    SciTech Connect

    Bobić, J.D.; Vijatović Petrović, M.M.; Banys, J.; Stojanović, B.D.

    2012-08-15

    Highlights: ► Pure and doped BaBi{sub 4}Ti{sub 4}O{sub 15} were prepared via the solid-state reaction method. ► The grain size was suppressed in Nb-doped samples. ► The diffuseness of the dielectric peak increased with dopant concentration. ► Niobium affected on relaxor behavior of barium bismuth titanate ceramics. ► The conductivity change was noticed in doped samples. -- Abstract: BaBi{sub 4}Ti{sub 4–5/4x}Nb{sub x}O{sub 15} (BBNTx, x = 0, 0.05, 0.15, 0.30) ceramics have been prepared by solid state method. XRD data indicate the formation of single-phase-layered perovskites for all compositions. SEM micrographs suggest that the grain size decreases with Nb doping. The effect of niobium doping on the dielectric and relaxor behavior of BaBi{sub 4}Ti{sub 4}O{sub 15} ceramics was investigated in a wide range of temperatures (20–777 °C) and frequencies (1.21 kHz to 1 MHz). Nb doping influences T{sub c} decrease as well as the decrease of dielectric permittivity at Curie temperature. At room temperature, undoped BaBi{sub 4}Ti{sub 4}O{sub 15} exhibits dielectric constant of ∼204 at 100 kHz, that slightly increases with Nb doping. The conductivity of BBNT5 ceramics is found to be lower than that of other investigated compositions. The value of activation energy of σ{sub DC} was found to be 0.89 eV, 1.01 eV, 0.93 eV and 0.71 eV for BBT, BBNT5, BBNT15 and BBNT30, respectively.

  7. Microbial Methylation of Metalloids: Arsenic, Antimony, and Bismuth

    PubMed Central

    Bentley, Ronald; Chasteen, Thomas G.

    2002-01-01

    A significant 19th century public health problem was that the inhabitants of many houses containing wallpaper decorated with green arsenical pigments experienced illness and death. The problem was caused by certain fungi that grew in the presence of inorganic arsenic to form a toxic, garlic-odored gas. The garlic odor was actually put to use in a very delicate microbiological test for arsenic. In 1933, the gas was shown to be trimethylarsine. It was not until 1971 that arsenic methylation by bacteria was demonstrated. Further research in biomethylation has been facilitated by the development of delicate techniques for the determination of arsenic species. As described in this review, many microorganisms (bacteria, fungi, and yeasts) and animals are now known to biomethylate arsenic, forming both volatile (e.g., methylarsines) and nonvolatile (e.g., methylarsonic acid and dimethylarsinic acid) compounds. The enzymatic mechanisms for this biomethylation are discussed. The microbial conversion of sodium arsenate to trimethylarsine proceeds by alternate reduction and methylation steps, with S-adenosylmethionine as the usual methyl donor. Thiols have important roles in the reductions. In anaerobic bacteria, methylcobalamin may be the donor. The other metalloid elements of the periodic table group 15, antimony and bismuth, also undergo biomethylation to some extent. Trimethylstibine formation by microorganisms is now well established, but this process apparently does not occur in animals. Formation of trimethylbismuth by microorganisms has been reported in a few cases. Microbial methylation plays important roles in the biogeochemical cycling of these metalloid elements and possibly in their detoxification. The wheel has come full circle, and public health considerations are again important. PMID:12040126

  8. The effect and mechanism of bismuth doped lead oxide on the performance of lead-acid batteries

    NASA Astrophysics Data System (ADS)

    Chen, H. Y.; Wu, L.; Ren, C.; Luo, Q. Z.; Xie, Z. H.; Jiang, X.; Zhu, S. P.; Xia, Y. K.; Luo, Y. R.

    Flooded automotive and motorcycle lead-acid batteries were manufactured from three kinds of lead oxides including electrolyzed pure lead (99.99 wt.% Pb) oxide, electrolyzed pure lead oxide doped with Bi 2O 3 (0.02 wt.% Bi 2O 3) and bismuth-bearing refined lead (0.02 wt.% Bi) oxide. The first cranking and cold cranking curves of the automotive batteries show that there is no obvious difference among the above lead oxides. Bismuth in lead oxide does not affect the water loss of flooded batteries. However, bismuth results in the improvement of capacity and charge-acceptance capability. In discharge, the positive voltage versus cadmium of plates with bismuth decreases more slowly than that of plates without bismuth. In order to investigate the mechanism of the function of bismuth, three other kinds of test electrodes were prepared from electrolyzed pure lead (99.99 wt.% Pb) oxide, electrolyzed pure lead oxide doped 0.02 wt.% Bi 2O 3 and electrolyzed pure lead oxide doped 0.06 wt.% Bi 2O 3. The cyclic voltammetry curve shows that bismuth has no significant influence on the electrochemical behavior of the positive active-material. There is an opposite result concerning the cathodic polarization curves between bismuth doped in the electrode and Bi 3+ ion doped in the electrolyte. Bismuth doped in the electrode results in a decrease of the hydrogen overpotential. Conversely, Bi 3+ ion doped in the electrolyte results is an increase. The chemical analysis confirms that a trace of Bi 3+ ion exists in sulfuric acid solution (e.g. plates soaking, after formation, after cycling). A higher porosity is observed in the positive active-material containing bismuth by SEM technique. SEM morphology shows that needle-like crystals begin to occur after a few cycles. X-ray diffraction phase analysis proves that the amount of α-PbO 2 is increased by doping bismuth in to lead oxide. The existing forms, chemical characteristics and electrochemical reactions of bismuth during manufacture

  9. NASA's Coastal and Ocean Airborne Science Testbed

    NASA Astrophysics Data System (ADS)

    Guild, L. S.; Dungan, J. L.; Edwards, M.; Russell, P. B.; Morrow, J. H.; Hooker, S.; Myers, J.; Kudela, R. M.; Dunagan, S.; Soulage, M.; Ellis, T.; Clinton, N. E.; Lobitz, B.; Martin, K.; Zell, P.; Berthold, R. W.; Smith, C.; Andrew, D.; Gore, W.; Torres, J.

    2011-12-01

    The Coastal and Ocean Airborne Science Testbed (COAST) Project is a NASA Earth-science flight mission that will advance coastal ecosystems research by providing a unique airborne payload optimized for remote sensing in the optically complex coastal zone. Teaming NASA Ames scientists and engineers with Biospherical Instruments, Inc. (San Diego) and UC Santa Cruz, the airborne COAST instrument suite combines a customized imaging spectrometer, sunphotometer system, and a new bio-optical radiometer package to obtain ocean/coastal/atmosphere data simultaneously in flight for the first time. The imaging spectrometer (Headwall) is optimized in the blue region of the spectrum to emphasize remote sensing of marine and freshwater ecosystems. Simultaneous measurements supporting empirical atmospheric correction of image data will be accomplished using the Ames Airborne Tracking Sunphotometer (AATS-14). Based on optical detectors called microradiometers, the NASA Ocean Biology and Biogeochemistry Calibration and Validation (cal/val) Office team has deployed advanced commercial off-the-shelf instrumentation that provides in situ measurements of the apparent optical properties at the land/ocean boundary including optically shallow aquatic ecosystems (e.g., lakes, estuaries, coral reefs). A complimentary microradiometer instrument package (Biospherical Instruments, Inc.), optimized for use above water, will be flown for the first time with the airborne instrument suite. Details of the October 2011 COAST airborne mission over Monterey Bay demonstrating this new airborne instrument suite capability will be presented, with associated preliminary data on coastal ocean color products, coincident spatial and temporal data on aerosol optical depth and water vapor column content, as well as derived exact water-leaving radiances.

  10. NCALM: NSF Supported Center for Airborne Laser Mapping

    NASA Astrophysics Data System (ADS)

    Shrestha, R. L.; Carter, W. E.; Dietrich, W. E.

    2003-12-01

    The National Science Foundation (NSF) recently awarded a grant to create a research center to support the use of airborne laser mapping technology in the scientific community. The NSF supported Center for Airborne Laser Mapping (NCALM) will be operated jointly by the Department of Civil & Coastal Engineering, College of Engineering, University of Florida (UF) and the Department of Earth and Planetary Science, University of California-Berkeley (UCB). NCALM will use the Airborne Laser Swath Mapping (ALSM) system jointly owned by UF and Florida International University (FIU), based at the UF Geosensing Engineering and Mapping (GEM) Research Center. The state-of-the-art laser surveying instrumentation, GPS systems, which are installed in a Cessna 337 Skymaster aircraft, will collect research grade data in areas selected through the competitive NSF grant review process. The ALSM observations will be analyzed both at UF and UCB, and made available to the PI through an archiving and distribution center at UCB-building upon the Berkeley Seismological Laboratory (BSL) Northern California Earthquake Data Center system. The purpose of NCALM is to provide research grade data from ALSM technology to NSF supported research studies in geosciences. The Center will also contribute to software development that will increase the processing speed and data accuracy. This presentation will discuss NCALM operation and the process of submitting proposals to NSF. In addition, it will outline the process to request available NCALM seed project funds to help jump-start small scientific research studies. Funds are also available for travel by academic researchers and students for hands-on knowledge and experience in ALSM technology at UF and UCB.

  11. Active airborne contamination control using electrophoresis

    SciTech Connect

    Veatch, B.D.

    1994-06-01

    In spite of our best efforts, radioactive airborne contamination continues to be a formidable problem at many of the Department of Energy (DOE) weapons complex sites. For workers that must enter areas with high levels of airborne contamination, personnel protective equipment (PPE) can become highly restrictive, greatly diminishing productivity. Rather than require even more restrictive PPE for personnel in some situations, the Rocky Flats Plant (RFP) is actively researching and developing methods to aggressively combat airborne contamination hazards using electrophoretic technology. With appropriate equipment, airborne particulates can be effectively removed and collected for disposal in one simple process. The equipment needed to implement electrophoresis is relatively inexpensive, highly reliable, and very compact. Once airborne contamination levels are reduced, less PPE is required and a significant cost savings may be realized through decreased waste and maximized productivity. Preliminary ``cold,`` or non-radioactive, testing results at the RFP have shown the technology to be effective on a reasonable scale, with several potential benefits and an abundance of applications.

  12. Airborne laser communication technology and flight test

    NASA Astrophysics Data System (ADS)

    Meng, Li-xin; Zhang, Li-zhong; Li, Xiao-ming; Li, Ying-chao; Jiang, Hui-lin

    2015-11-01

    Reconnaissance aircraft is an important node of the space-air-ground integrated information network, on which equipped with a large number of high-resolution surveillance equipment, and need high speed communications equipment to transmit detected information in real time. Currently RF communication methods cannot meet the needs of communication bandwidth. Wireless laser communication has outstanding advantages high speed, high capacity, security, etc., is an important means to solve the high-speed information transmission of airborne platforms. In this paper, detailed analysis of how the system works, the system components, work processes, link power and the key technologies of airborne laser communication were discussed. On this basis, a prototype airborne laser communications was developed, and high-speed, long-distance communications tests were carried out between the two fixed-wing aircraft, and the airborne precision aiming, atmospheric laser communication impacts on laser communication were tested. The experiments ultimately realize that, the communication distance is 144km, the communication rate is 2.5Gbps. The Airborne laser communication experiments provide technical basis for the application of the conversion equipment.

  13. Airborne Gravimetry and Downward Continuation (Invited)

    NASA Astrophysics Data System (ADS)

    Jekeli, C.; Yang, H.; Kwon, J.

    2009-12-01

    Measuring the Earth’s gravity field using airborne instrumentation is fully operational and has been widely practiced for nearly three decades since its official debut in the early 1980s (S. Hammer: “Airborne Gravity is Here!”) coinciding with the precision kinematic positioning capability of GPS. Airborne gravimetry is undertaken for both efficient geophysical exploration purposes, as well as the determination of the regional geoid to aid in the modernization of height systems. Especially for the latter application, downward continuation of the data and combination with existing terrestrial gravimetry pose theoretical as well as practical challenges, which, on the other hand, create multiple processing possibilities. Downward continuation may be approached in various ways from the viewpoint of potential theory and the boundary-value problem to using gradients either estimated locally or computed from existing models. Logistical constraints imposed by the airborne survey, instrumental noise, and the intrinsic numerical instability of downward continuation all conspire to impact the final product in terms of achievable resolution and accuracy. In this paper, we review the theory of airborne gravimetry and the methodology of downward continuation, and provide a numerical comparison of possible schemes and their impact on geoid determination.

  14. Improvements in the energy resolution and high-count-rate performance of bismuth germanate

    SciTech Connect

    Koehler, P.E.; Wender, S.A.; Kapustinsky, J.S.

    1985-01-01

    Several methods for improving the energy resolution of bismuth germanate (BGO) have been investigated. It is shown that some of these methods resulted in a substantial improvement in the energy resolution. In addition, a method to improve the performance of BGO at high counting rates has been systematically studied. The results of this study are presented and discussed.

  15. Pepto bismuth associated neurotoxicity: A rare side effect of a commonly used medication.

    PubMed

    Masannat, Yanal; Nazer, Eyad

    2013-01-01

    A 56 years old female with medical history significant for collagenous colitis and GERD for which she was taking Pepto Bismuth for months. She presented with progressive confusion for two weeks, followed by myoclonus, tremors, gait instability and visual hallucinations. Patient was admitted and comprehensive work up was done over a ten day course. This included a CBC, CCP CT head, MRI brain, EEG, Lumbar puncture, and various antibody and serology testing which were all essentially unremarkable. It was noted that patient had been taking OTC Pepto Bismuth chronically for GI symptoms. Based upon the unrevealing work up, serum and urine samples for Bismuth levels were sent and returned markedly positive in both samples. Bismuth was held on admission and over the ten day hospitalization, patient showed gradual improvement of her cognitive function. She also showed resolution of her abnormal movements, myoclonus and visual hallucinations. Her gait continued to improve and required extended period of physical therapy post discharge. Her subsequent follow up visits showed resolution to baseline at four months post discharge. PMID:23798279

  16. Bismuth-embedded SBA-15 mesoporous silica for radioactive iodine capture and stable storage

    NASA Astrophysics Data System (ADS)

    Yang, Jae Hwan; Cho, Yong-Jun; Shin, Jin Myeong; Yim, Man-Sung

    2015-10-01

    Efficient capture and stable storage of the long-lived iodine-129 (129I), released as off-gas from nuclear fuel reprocessing, have been of significant concern in the waste management field. In this study, bismuth-embedded SBA-15 mesoporous silica was firstly applied for iodine capture and storage. SBA-15 was functionalized with thiol (-SH) groups, followed by bismuth adsorption with Bi-S bonding, which was thermally treated to form Bi2S3 within SBA-15. The bismuth-embedded SBA-15s demonstrated high iodine loading capacities (up to 540 mg-I/g-sorbent), which benefitted from high surface area and porosity of SBA-15 as well as the formation of thermodynamically stable BiI3 compound. Iodine physisorption was effectively suppressed due to the large pores present in SBA-15, resulting in chemisorption as a main mechanism for iodine confinement. Furthermore, a chemically durable iodine-bearing material was made with a facile post-sorption process, during which the iodine-incorporated phase was changed from BiI3 to chemically durable Bi5O7I. Thus, our results showed that both efficient capture and stabilization of 129I would be possible with the bismuth-embedded SBA-15, in contrast to other sorbents mainly focused on iodine capture.

  17. Problems of development the pilot lead-bismuth target circuit TC-1 for ADS

    SciTech Connect

    Ignatiev, Sviatoslav; Leonchuk, Mikhail; Orlov, Yury; Pankratov, Dmitry; Suvorov, Gennady; Zabudko, Alexey

    2007-07-01

    Available in abstract form only. Full text of publication follows: Main problems on development of pilot molten lead-bismuth target circuit of 1 MW proton beam power (TC-1) as an important part of target-blanket accelerator driven system (ADS) for nuclear waste incineration are analyzed. (authors)

  18. Renal pigmentation due to chronic bismuth administration in a rhesus macaque (Macaca mulatta).

    PubMed

    Johnson, A L; Blaine, E T; Lewis, A D

    2015-05-01

    Renal pigmentation due to the administration of exogenous compounds is an uncommon finding in most species. This report describes renal pigmentation and intranuclear inclusions of the proximal convoluted tubules due to chronic bismuth administration in a rhesus macaque. An 11-year-old Indian-origin rhesus macaque with a medical history of chronic intermittent vomiting had been treated with bismuth subsalicylate, famotidine, and omeprazole singly or in combination over the course of 8 years. At necropsy, the renal cortices were diffusely dark green to black. Light and electron microscopy revealed intranuclear inclusions within the majority of renal proximal tubular epithelial cells. These inclusions appeared magenta to brown when stained with hematoxylin and eosin and were negative by the Ziehl-Neelsen acid-fast stain. Elemental analysis performed on frozen kidney measured bismuth levels to be markedly elevated at 110.6 ppm, approximately 500 to 1000 times acceptable limits. To our knowledge, this is the first report of renal bismuth deposition in a rhesus macaque resulting in renal pigmentation and intranuclear inclusions. PMID:24990482

  19. Bismuth coordination networks containing deferiprone: synthesis, characterisation, stability and antibacterial activity.

    PubMed

    Burrows, Andrew D; Jurcic, Monika; Mahon, Mary F; Pierrat, Sandrine; Roffe, Gavin W; Windle, Henry J; Spencer, John

    2015-08-21

    A series of bismuth-dicarboxylate-deferiprone coordination networks have been prepared and structurally characterised. The new compounds have been demonstrated to release the iron overload drug deferiprone on treatment with PBS and have also been shown to have antibacterial activity against H. pylori. PMID:26172618

  20. Group III-nitride thin films grown using MBE and bismuth

    DOEpatents

    Kisielowski, Christian K.; Rubin, Michael

    2002-01-01

    The present invention comprises growing gallium nitride films in the presence of bismuth using MBE at temperatures of about 1000 K or less. The present invention further comprises the gallium nitride films fabricated using the inventive fabrication method. The inventive films may be doped with magnesium or other dopants. The gallium nitride films were grown on sapphire substrates using a hollow anode Constricted Glow Discharge nitrogen plasma source. When bismuth was used as a surfactant, two-dimensional gallium nitride crystal sizes ranging between 10 .mu.m and 20 .mu.m were observed. This is 20 to 40 times larger than crystal sizes observed when GaN films were grown under similar circumstances but without bismuth. It is thought that the observed increase in crystal size is due bismuth inducing an increased surface diffusion coefficient for gallium. The calculated value of 4.7.times.10.sup.-7 cm.sup.2 /sec. reveals a virtual substrate temperature of 1258 K which is 260 degrees higher than the actual one.

  1. Oxygen-iron interaction in liquid lead-bismuth eutectic alloy.

    PubMed

    Aerts, A; Gavrilov, S; Manfredi, G; Marino, A; Rosseel, K; Lim, J

    2016-07-20

    Iron released by steel corrosion was found to be a key impurity in reactions with dissolved oxygen in liquid lead-bismuth eutectic alloys. The iron-oxygen-magnetite equilibrium was characterized, allowing the quantification of phenomena that are important for long-term operation of lead-alloy based installations such as corrosion rate control and management of precipitates. PMID:27383127

  2. Effect of bismuth citrate, lactose, and organic acid on necrotic enteritis in broilers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Clostridium perfringens – associated necrotic enteritis causes significant losses and increased morbidity in poultry. The objective of this study was to evaluate the effect of bismuth citrate and acidifiers on the development of necrotic enteritis in broilers. The first study was a dose response t...

  3. Group III-nitride thin films grown using MBE and bismuth

    DOEpatents

    Kisielowski, Christian K.; Rubin, Michael

    2000-01-01

    The present invention comprises growing gallium nitride films in the presence of bismuth using MBE at temperatures of about 1000 K or less. The present invention further comprises the gallium nitride films fabricated using the inventive fabrication method. The inventive films may be doped with magnesium or other dopants. The gallium nitride films were grown on sapphire substrates using a hollow anode Constricted Glow Discharge nitrogen plasma source. When bismuth was used as a surfactant, two-dimensional gallium nitride crystal sizes ranging between 10 .mu.m and 20 .mu.m were observed. This is 20 to 40 times larger than crystal sizes observed when GaN films were grown under similar circumstances but without bismuth. It is thought that the observed increase in crystal size is due bismuth inducing an increased surface diffusion coefficient for gallium. The calculated value of 4.7.times.10.sup.-7 cm.sup.2 /sec. reveals a virtual substrate temperature of 1258 K which is 260 degrees higher than the actual one.

  4. Determination of (111) ordered domains on platinum electrodes by irreversible adsorption of bismuth.

    PubMed

    Rodríguez, Paramaconi; Solla-Gullón, José; Vidal-Iglesias, Francisco J; Herrero, Enrique; Aldaz, Antonio; Feliu, Juan M

    2005-08-15

    Irreversible adsorbed bismuth can be used to determine the fraction of (111) domains on a given platinum sample. On Pt(111) electrodes, the surface redox process of adsorbed bismuth takes place at 0.63 V in a well-defined peak. The behavior of this redox process on the Pt(111) vicinal surfaces indicates that the bismuth atoms involved in the redox process are only those deposited on the (111) terrace sites and that the charge under the peak at 0.63 V is directly proportional to the number of sites on (111) ordered domains (terraces). The good linear relationship obtained between the charge for the bismuth redox process and the number of (111) terrace sites on the vicinal surfaces allows construction of a calibration curve. This calibration curve has been used to directly estimate the amount of (111) ordered domain terrace sites on polycrystalline platinum samples with different surface ordered domains. The results agree with what we would expect from our knowledge of these surfaces. PMID:16097774

  5. Separation of Americium in High Oxidation States from Curium Utilizing Sodium Bismuthate.

    PubMed

    Richards, Jason M; Sudowe, Ralf

    2016-05-01

    A simple separation of americium from curium would support closure of the nuclear fuel cycle, assist in nuclear forensic analysis, and allow for more accurate measurement of neutron capture properties of (241)Am. Methods for the separation of americium from curium are however complicated and time-consuming due to the similar chemical properties of these elements. In this work a novel method for the separation of americium from curium in nitric acid media was developed using sodium bismuthate to perform both the oxidation and separation. Sodium bismuthate is shown to be a promising material for performing a simple and rapid separation. Curium is more strongly retained than americium on the undissolved sodium bismuthate at nitric acid concentrations below 1.0 M. A separation factor of ∼90 was obtained in 0.1 M nitric acid. This separation factor is achieved within the first minute of contact and is maintained for at least 2 h of contact. Separations using sodium bismuthate were performed using solid-liquid extraction as well as column chromatography. PMID:27079565

  6. 1.3 µm Raman-bismuth fiber amplifier pumped by semiconductor disk laser.

    PubMed

    Chamorovskiy, A; Rautiainen, J; Rantamäki, A; Golant, K M; Okhotnikov, O G

    2011-03-28

    A hybrid Raman-bismuth fiber amplifier pumped in co-propagation configuration by a single 1.22 µm semiconductor disk laser is presented. The unique attribute of this dual-gain system is that both amplifiers require the pump source with the same wavelength because pump-Stokes spectral shift in 1.3 µm Raman amplifier and pump-gain bandwidth separation in 1.3 µm bismuth fiber amplifier have the same value. Residual pump power at the output of Raman amplifier in this scheme is efficiently consumed by bismuth-doped fiber thus increasing the overall conversion efficiency. The small-signal gain of 18 dB at 1.3 W of pump power has been achieved for hybrid scheme which is by 9 dB higher as compared with isolated Raman amplifier without bismuth fiber. Low noise performance of pump semiconductor disk laser with RIN of -150 dB/Hz combined with nearly diffraction-limited beam quality and Watt-level output powers allows for efficient core-pumping of a single-mode fiber amplifier systems and opens up new opportunities for amplification in O-band spectral range. PMID:21451671

  7. 40 CFR 471.10 - Applicability; description of the lead-tin-bismuth forming subcategory.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 29 2010-07-01 2010-07-01 false Applicability; description of the lead-tin-bismuth forming subcategory. 471.10 Section 471.10 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS NONFERROUS METALS FORMING AND METAL...

  8. 40 CFR 471.10 - Applicability; description of the lead-tin-bismuth forming subcategory.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 30 2011-07-01 2011-07-01 false Applicability; description of the lead-tin-bismuth forming subcategory. 471.10 Section 471.10 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS NONFERROUS METALS FORMING AND METAL...

  9. Catalytic oxidation of propylene--7. Use of temperature programmed reoxidation to characterize. gamma. -bismuth molybdate

    SciTech Connect

    Uda, T.; Lin, T.T.; Keulks, G.W.

    1980-03-01

    Temperature-programed reoxidation of propylene-reduced ..gamma..-Bi/sub 2/MoO/sub 6/ revealed a low-temperature peak (LTP) at 158/sup 0/C and a high-temperature peak (HTP) at 340/sup 0/C. Auger spectroscopy and X-ray diffraction of reduced and partially or completely reoxidized bismuth molybdate showed that at the LTP, molybdenum(IV) is oxidized to molybdenum(VI) and bismuth, from the metallic state to an oxidation state between zero and three, and that the HTP is associated with the complete oxidation of bismuth to bismuth(III). Activity tests for propylene oxidation showed lower acrolein formation on the catalyst, on which only the LTP was reoxidized than on catalysts on which both peaks were reoxidized. The reoxidation kinetics of the catalyst under conditions corresponding to the LTP showed an activation energy of 22.9 kcal/mole below 170/sup 0/C and near zero above 170/sup 0/C; the break in the Arrhenius plot of reoxidation of the catalyst under conditions corresponding to the HTP was at 400/sup 0/C, with activation energies of 46 kcal/mole at lower and near zero at higher temperatures. Propylene oxidation was apparently rate-limited by the HTP reoxidation process below 400/sup 0/C and by allylic hydrogen abstraction above 400/sup 0/C.

  10. Robust synthesis of bismuth titanate pyrochlore nanorods and their photocatalytic applications.

    PubMed

    Murugesan, Sankaran; Subramanian, Vaidyanathan Ravi

    2009-09-14

    A facile and template-free reverse micelle-based method can be employed to synthesize highly crystalline and pure stoichiometric bismuth titanate (Bi(2)Ti(2)O(7)) pyrochlore nanorods 400-500 nm long and 40-50 nm in diameter which demonstrate promising photoactivity. PMID:20448962

  11. Microwave and magneto-optic properties of bismuth-substituted yttrium iron garnet thin films

    NASA Astrophysics Data System (ADS)

    Butler, J. C.; Kramer, J. J.; Esman, R. D.; Craig, A. E.; Lee, J. N.; Ryuo, T.

    1990-05-01

    Microwave and magneto-optic measurements have been made on bismuth-substituted yttrium iron garnet (BiYIG) films. Forward-volume (FV) magnetostatic-wave (MSW) attenuation has been measured from ferrimagnetic resonance and from pulse delay data. We report the indirect observation of FV MSW in BiYIG using two independent techniques: a pulse transmission technique and a passband measurement technique. Faraday rotation in the films was also recorded at a wavelength of 1.3 μm. The bismuth-substituted films are grown on carefully cleaned substrates and have yttrium:bismuth ratios of 1:1. The composition of the bismuth substituted films is Y1.5Bi1.5Fe5O12 deduced from lattice parameters and absolute Faraday rotation. These films show particular promise for use in waveguide-type high-speed MSW-optical devices where low MSW attenuation and high Faraday rotation are among the necessary criteria for successful operation.

  12. The study of tribological performance and surface film characterization of bismuth dioctyldithiocarbamate

    SciTech Connect

    Chen Ligong; Dong Junxiu; Chen Guoxu

    1997-05-01

    In this study, bismuth dioctyldithiocarbamate has been synthesized, and its tribological behaviors, such as friction-reducing ability, antiwear property and extreme pressure performance have been respectively evaluated with a ring-on-block test rig and a fourball machine. In addition to correlate its tribological behaviors with the film formed on the metallic rubbing surface under boundary lubrication conditions, surface analyses have been conducted to characterize the surface film by means of Auger electron spectroscopy (AES), X-ray photoelectron spectroscopy (XPS) and energy dispersion of X-ray (EDX). Test results show the additive compound can effectively improve the friction and wear of the rubbing couples. On the other hand, EDX confirmed the presence of carbon, oxygen, sulfur, nitrogen, bismuth and iron on the surface; AES revealed their depth distribution of atomic concentration percentages. Whereas XPS further disclosed that the composition of the surface film was composed of organic and inorganic species including iron sulfide and sulfate, metallic bismuth, bismuth oxide and sulfide, etc. which are conducive to the reduction of friction and wear.

  13. The effect of integration of Strontium-Bismuth-Tantalate capacitors onto SOI wafers

    NASA Technical Reports Server (NTRS)

    Joshi, Vikram; Ohno, Morifumo; Ida, Jiro; Nagatomo, Yoshiki; Strauss, Karl

    2005-01-01

    We report for the first time the successful integration of Strontium-Bismuth-Tantalate ferroelectric capacitors on an SOI Substrate. We have verified that the unique processing requirements of SBT capacitors does not affect the properties of the surrounding FD-SOI transistors, and, conversely, we have verified that the SOI processing does not affect the quality of the SBT capacitors.

  14. The Effect of Integration of Strontium-Bismuth-Tantalate Capacitors onto SOI Wafers

    NASA Technical Reports Server (NTRS)

    Strauss, Karl F.; Joshi, Vikram; Ohno, Morifumo; Ida, Jiro; Nagatomo, Yoshiki

    2006-01-01

    We report for the first time the successful integration of Strontium-Bismuth-Tantalate ferroelectric capacitors on an SOI Substrate. We have verified that the unique processing requirements of SBT capacitors does not affect the properties of the surrounding FD-SOI transistors, and, conversely, we have verified that the SOI processing does not affect the quality of the SBT capacitors.

  15. The antimicrobial effects and metabolomic footprinting of carboxyl-capped bismuth nanoparticles against Helicobacter pylori.

    PubMed

    Nazari, P; Dowlatabadi-Bazaz, R; Mofid, M R; Pourmand, M R; Daryani, N E; Faramarzi, M A; Sepehrizadeh, Z; Shahverdi, A R

    2014-01-01

    Organic salts of bismuth are currently used as antimicrobial agents against Helicobacter pylori. This study evaluated the antibacterial effect of elemental bismuth nanoparticles (Bi NPs) using a serial agar dilution method for the first time against different clinical isolates and a standard strain of H. pylori. The Bi NPs were biologically prepared and purified by a recently described method and subjected to further characterization by infrared spectroscopy and anti-H. pylori evaluation. Infrared spectroscopy results showed the presence of carboxyl functional groups on the surface of biogenic Bi NPs. These biogenic nanoparticles showed good antibacterial activity against all tested H. pylori strains. The resulting MICs varied between 60 and 100 μg/ml for clinical isolates of H. pylori and H. pylori (ATCC 26695). The antibacterial effect of bismuth ions was also tested against all test strains. The antimicrobial effect of Bi ions was lower than antimicrobial effect of bismuth in the form of elemental NPs. The effect of Bi NPs on metabolomic footprinting of H. pylori was further evaluated by (1)H NMR spectroscopy. Exposure of H. pylori to an inhibitory concentration of Bi NPs (100 μg/ml) led to release of some metabolites such as acetate, formic acid, glutamate, valine, glycine, and uracil from bacteria into their supernatant. These findings confirm that these nanoparticles interfere with Krebs cycle, nucleotide, and amino acid metabolism and shows anti-H. pylori activity. PMID:24104691

  16. Bismuth-doped telecommunication fibres for lasers and amplifiers in the 1400-1500-nm region

    SciTech Connect

    Dvoirin, V V; Mashinskii, V M; Medvedkov, O I; Dianov, Evgenii M; Umnikov, A A; Gur'yanov, Aleksei N

    2009-06-30

    Bismuth-doped optical fibres fully compatible with standard telecommunication fibres are developed. Lasers based on such fibres emitting in the spectral range 1430-1500 nm with an efficiency of up to 7.6% at room temperature and up to 10.5% at a temperature of -65{sup 0}C are fabricated. (waveguides. optical fibres)

  17. Bismuth-doped-glass optical fibers--a new active medium for lasers and amplifiers.

    PubMed

    Dvoyrin, V V; Mashinsky, V M; Bulatov, L I; Bufetov, I A; Shubin, A V; Melkumov, M A; Kustov, E F; Dianov, E M; Umnikov, A A; Khopin, V F; Yashkov, M V; Guryanov, A N

    2006-10-15

    Optical fibers with bismuth-doped silicate and germanate glass cores were fabricated by the modified chemical vapor deposition technique (solution and vapor-phase Bi incorporation). The fibers revealed an efficient luminescence with a maximum in the 1050-1200 nm spectral range, FWHM up to 200 nm, and a lifetime of the order of 1 ms. PMID:17001368

  18. Bismuth-induced dielectric relaxation in the (1-x)La(Mg{sub 1/2}Ti{sub 1/2})O{sub 3}-xBi(Mg{sub 1/2}Ti{sub 1/2})O{sub 3} perovskite system

    SciTech Connect

    Salak, Andrei N.; Pullar, Robert C.; Alford, Neil McN.

    2008-07-01

    The temperature variation of the dielectric permittivity and loss of the solid solutions (1-x)La(Mg{sub 1/2}Ti{sub 1/2})O{sub 3}-xBi(Mg{sub 1/2}Ti{sub 1/2})O{sub 3} [(1-x)LMT-xBMT] (0{<=}x{<=}0.3) measured at radio, microwave, and far infrared frequency ranges has been analyzed in comparison with that observed in other bismuth-containing and bismuth-free perovskite ceramics based on LMT. It has been found that the low temperature dielectric response of the (1-x)LMT-xBMT compositions with x{>=}0 is frequency dependent over a wide range from radio to microwave frequencies. The considerable compositional growth of the dielectric permittivity and loss associated with the amount of bismuth in the system was revealed to be not contributed by the lattice polar phonon modes. The effect was suggested to be related to the low-temperature dielectric relaxation process due to a hopping movement of charge carriers in crystallographic A-sites of the perovskite lattice. Particular role of local lattice distortions caused by the anisotropic chemical bonds involving bismuth 6s{sup 2} electrons in a localization of hopping charge carriers in perovskites and other oxygen-octahedral compositions is considered. The characteristic features of the Bi-induced dielectric relaxation and those typical of the ferroelectric relaxors are compared and discussed.

  19. Hall Plateaus at magic angles in ultraquantum Bismuth

    NASA Astrophysics Data System (ADS)

    Benoît, Fauqué.

    2009-03-01

    The behaviour of a three-dimensional electron gas in the presence of a magnetic field strong enough to put all carriers in the first Landau level (i.e. beyond the quantum limit) is a longstanding question of theoretical condensed matter physics [1]. This issue has been recently explored by two high-field experiments on elemental semi-metal Bismuth. In a first study of transport coefficients (which are dominated by hole-like carriers), the Nernst coefficient presented three unexpected maxima that are concomitant with quasi-plateaux in the Hall coefficient [2]. In a second series of experiments, torque magnetometry (which mainly probes the three Dirac valley electron pockets) detected a field-induced phase transition [3]. The full understanding of the electron and hole behaviours above the quantum limit of pure Bi is therefore still under debate. In this talk, we will present our measurement of the Hall resistivity and torque magnetometry with magnetic field up to 31 T and rotating in the trigonal-bisectrix plane [4]. The Hall response is dominated by the hole pockets according to its sign as well as the period and the angular dependence of its quantum oscillations. In the vicinity of the quantum limit, it presents additional anomalies which are the fingerprints of the electron pockets. We found that for particular orientations of the magnetic field (namely ``magic angles''), the Hall response becomes field-independent within the experimental resolution around 20T. This drastic dependence of the plateaux on the field orientation provides strong constraints for theoretical scenarios. [4pt] [1] Bertrand I. Halperin, Japanese Journal of Applied Physics, 26, Supplement 26-3 (1987).[0pt] [2] Kamran Behnia, Luis Balicas, Yakov Kopelevich, Science, 317, 1729 (2008).[0pt] [3] Lu Li, J. G. Checkelsky, Y. S. Hor, C. Uher, A. F. Hebard, R. J. Cava, and N. P. Ong , Science, 321, 5888 (2008).[0pt] [4] Benoît Fauqu'e, Luis Balicas, Ilya Sheikin, Jean Paul Issi and Kamran Behnia

  20. Electrodeposition and device incorporation of bismuth antimony nanowire arrays

    NASA Astrophysics Data System (ADS)

    Keyani, Jennifer

    Thermoelectric materials have the unique property where the application of a potential difference across the material results in the formation of a temperature gradient, and vice versa. There is continued interest in bulk thermoelectric materials for power generation and refrigeration applications, however these materials are not currently in widespread use due to their low conversion efficiency. It has been predicted that nanostructured thermoelectric materials will show enhanced performance over their bulk counterparts. In this study, bismuth antimony (Bi1-xSbx) nanowire arrays have been synthesized and assembled into devices in order to demonstrate an enhanced performance in nanostructured thermoelectric materials. Bi1-xSbx nanowire arrays were fabricated by potentiostatic electrodeposition into porous alumina templates from a dimethyl sulfoxide (DMSO) solution. The nanowire composition and texture were studied as a function of the electrodeposition conditions in order to maximize their thermoelectric performance. Energy dispersive spectrometry and electron microprobe analysis were used to study the nanowire composition as a function of the electroactive and non-electroactive species in solution. Texturing in the nanowire arrays was observed by X-ray diffraction and controlled by the applied voltage and presence of supporting electrolyte. The nanowire arrays were also optimized for device incorporation by maximizing the number of nanowires and minimizing their length distribution. The areal density of nanowire arrays was on the order of 1010 wires/cm2 due to the high density of pores in the alumina and the high degree to which those pores were filled with electrodeposited material. A narrow distribution of nanowire lengths was observed by scanning electron microscopy across millimeter-length portions of the arrays. A hybrid nanowire-bulk thermoelectric device was assembled after electrical contacts were electrodeposited over Bi1-xSbx nanowire arrays. Nickel was

  1. Improvements to a Flow Sensor for Liquid Bismuth-Fed Hall Thrusters

    NASA Technical Reports Server (NTRS)

    Bonds, Kevin; Polzin, Kurt A.

    2010-01-01

    Recently, there has been significant interest in using bismuth metal as a propellant in Hall Thrusters [1, 2]. Bismuth offers some considerable cost, weight, and space savings over the traditional propellant--xenon. Quantifying the performance of liquid metal-fed Hall thrusters requires a very precise measure of the low propellant flow rates [1, 2]. The low flow rates (10 mg/sec) and the temperature at which free flowing liquid bismuth exists (above 300 C) preclude the use of off-the-shelf flow sensing equipment [3]. Therefore a new type of sensor is required. The hotspot bismuth flow sensor, described in Refs. [1-5] is designed to perform a flow rate measurement by measuring the velocity at which a thermal feature moves through a flow chamber. The mass flow rate can be determined from the time of flight of the thermal peak, [4, 5]. Previous research and testing has been concerned mainly with the generation of the thermal peak and it's subsequent detection. In this paper, we present design improvements to the sensor concept; and the results of testing conducted to verify the functionality of these improvements. A ceramic material is required for the sensor body (see Fig. 1), which must allow for active heating of the bismuth flow channel to keep the propellant in a liquid state. The material must be compatible with bismuth and must be bonded to conductive elements to allow for conduction of current into the liquid metal and measurement of the temperature in the flow. The new sensor requires fabrication techniques that will allow for a very small diameter flow chamber, which is required to produce useful measurements. Testing of various materials has revealed several that are potentially compatible with liquid bismuth. Of primary concern in the fabrication and testing of a robust, working prototype, is the compatibility of the selected materials with one another. Specifically, the thermal expansion rates of the materials relative to the ceramic body cannot expand so

  2. Airborne Microalgae: Insights, Opportunities, and Challenges.

    PubMed

    Tesson, Sylvie V M; Skjøth, Carsten Ambelas; Šantl-Temkiv, Tina; Löndahl, Jakob

    2016-04-01

    Airborne dispersal of microalgae has largely been a blind spot in environmental biological studies because of their low concentration in the atmosphere and the technical limitations in investigating microalgae from air samples. Recent studies show that airborne microalgae can survive air transportation and interact with the environment, possibly influencing their deposition rates. This minireview presents a summary of these studies and traces the possible route, step by step, from established ecosystems to new habitats through air transportation over a variety of geographic scales. Emission, transportation, deposition, and adaptation to atmospheric stress are discussed, as well as the consequences of their dispersal on health and the environment and state-of-the-art techniques to detect and model airborne microalga dispersal. More-detailed studies on the microalga atmospheric cycle, including, for instance, ice nucleation activity and transport simulations, are crucial for improving our understanding of microalga ecology, identifying microalga interactions with the environment, and preventing unwanted contamination events or invasions. PMID:26801574

  3. Airborne pollen trends in the Iberian Peninsula.

    PubMed

    Galán, C; Alcázar, P; Oteros, J; García-Mozo, H; Aira, M J; Belmonte, J; Diaz de la Guardia, C; Fernández-González, D; Gutierrez-Bustillo, M; Moreno-Grau, S; Pérez-Badía, R; Rodríguez-Rajo, J; Ruiz-Valenzuela, L; Tormo, R; Trigo, M M; Domínguez-Vilches, E

    2016-04-15

    Airborne pollen monitoring is an effective tool for studying the reproductive phenology of anemophilous plants, an important bioindicator of plant behavior. Recent decades have revealed a trend towards rising airborne pollen concentrations in Europe, attributing these trends to an increase in anthropogenic CO2 emissions and temperature. However, the lack of water availability in southern Europe may prompt a trend towards lower flowering intensity, especially in herbaceous plants. Here we show variations in flowering intensity by analyzing the Annual Pollen Index (API) of 12 anemophilous taxa across 12 locations in the Iberian Peninsula, over the last two decades, and detecting the influence of the North Atlantic Oscillation (NAO). Results revealed differences in the distribution and flowering intensity of anemophilous species. A negative correlation was observed between airborne pollen concentrations and winter averages of the NAO index. This study confirms that changes in rainfall in the Mediterranean region, attributed to climate change, have an important impact on the phenology of plants. PMID:26803684

  4. Airborne Microalgae: Insights, Opportunities, and Challenges

    PubMed Central

    Skjøth, Carsten Ambelas; Šantl-Temkiv, Tina; Löndahl, Jakob

    2016-01-01

    Airborne dispersal of microalgae has largely been a blind spot in environmental biological studies because of their low concentration in the atmosphere and the technical limitations in investigating microalgae from air samples. Recent studies show that airborne microalgae can survive air transportation and interact with the environment, possibly influencing their deposition rates. This minireview presents a summary of these studies and traces the possible route, step by step, from established ecosystems to new habitats through air transportation over a variety of geographic scales. Emission, transportation, deposition, and adaptation to atmospheric stress are discussed, as well as the consequences of their dispersal on health and the environment and state-of-the-art techniques to detect and model airborne microalga dispersal. More-detailed studies on the microalga atmospheric cycle, including, for instance, ice nucleation activity and transport simulations, are crucial for improving our understanding of microalga ecology, identifying microalga interactions with the environment, and preventing unwanted contamination events or invasions. PMID:26801574

  5. Airborne space laser communication system and experiments

    NASA Astrophysics Data System (ADS)

    Li, Xiao-Ming; Zhang, Li-zhong; Meng, Li-Xin

    2015-11-01

    Airborne space laser communication is characterized by its high speed, anti-electromagnetic interference, security, easy to assign. It has broad application in the areas of integrated space-ground communication networking, military communication, anti-electromagnetic communication. This paper introduce the component and APT system of the airborne laser communication system design by Changchun university of science and technology base on characteristic of airborne laser communication and Y12 plan, especially introduce the high communication speed and long distance communication experiment of the system that among two Y12 plans. In the experiment got the aim that the max communication distance 144Km, error 10-6 2.5Gbps - 10-7 1.5Gbps capture probability 97%, average capture time 20s. The experiment proving the adaptability of the APT and the high speed long distance communication.

  6. Airborne soil organic particles generated by precipitation

    DOE PAGESBeta

    Wang, Bingbing; Harder, Tristan H.; Kelly, Stephen T.; Piens, Dominique S.; China, Swarup; Kovarik, Libor; Keiluweit, Marco; Arey, Bruce W.; Gilles, Mary K.; Laskin, Alexander

    2016-05-02

    Airborne organic particles play a critical role in Earth’s climate1, public health2, air quality3, and hydrological and carbon cycles4. However, sources and formation mechanisms for semi-solid and solid organic particles5 are poorly understood and typically neglected in atmospheric models6. Laboratory evidence suggests that fine particles can be formed from impaction of mineral surfaces by droplets7. Here, we use chemical imaging of particles collected following rain events in the Southern Great Plains, Oklahoma, USA and after experimental irrigation to show that raindrop impaction of soils generates solid organic particles. We find that after rain events, sub-micrometre solid particles, with a chemicalmore » composition consistent with soil organic matter, contributed up to 60% of atmospheric particles. Our irrigation experiments indicate that intensive water impaction is sufficient to cause ejection of airborne soil organic particles from the soil surface. Chemical imaging and micro-spectroscopy analysis of particle physico-chemical properties suggest that these particles may have important impacts on cloud formation and efficiently absorb solar radiation. Lastly, we suggest that raindrop-induced formation of solid organic particles from soils may be a widespread phenomenon in ecosystems such as agricultural systems and grasslands where soils are exposed to strong, episodic precipitation events8.« less

  7. Airborne Measurements of Coarse Mode Aerosol Composition and Abundance

    NASA Astrophysics Data System (ADS)

    Froyd, K. D.; Murphy, D. M.; Brock, C. A.; Ziemba, L. D.; Anderson, B. E.; Wilson, J. C.

    2015-12-01

    Coarse aerosol particles impact the earth's radiative balance by direct scattering and absorption of light and by promoting cloud formation. Modeling studies suggest that coarse mode mineral dust and sea salt aerosol are the dominant contributors to aerosol optical depth throughout much of the globe. Lab and field studies indicate that larger aerosol particles tend to be more efficient ice nuclei, and recent airborne measurements confirm the dominant role of mineral dust on cirrus cloud formation. However, our ability to simulate coarse mode particle abundance in large scale models is limited by a lack of validating measurements above the earth's surface. We present airborne measurements of coarse mode aerosol abundance and composition over several mid-latitude, sub-tropical, and tropical regions from the boundary layer to the stratosphere. In the free troposphere the coarse mode constitutes 10-50% of the total particulate mass over a wide range of environments. Above North America mineral dust typically dominates the coarse mode, but biomass burning particles and sea salt also contribute. In remote environments coarse mode aerosol mainly consists of internally mixed sulfate-organic particles. Both continental and marine convection can enhance coarse aerosol mass through direct lofting of primary particles and by secondary accumulation of aerosol material through cloud processing.

  8. Classification of airborne laser scanning data using JointBoost

    NASA Astrophysics Data System (ADS)

    Guo, Bo; Huang, Xianfeng; Zhang, Fan; Sohn, Gunho

    2015-02-01

    The demands for automatic point cloud classification have dramatically increased with the wide-spread use of airborne LiDAR. Existing research has mainly concentrated on a few dominant objects such as terrain, buildings and vegetation. In addition to those key objects, this paper proposes a supervised classification method to identify other types of objects including power-lines and pylons from point clouds using a JointBoost classifier. The parameters for the learning model are estimated with various features computed based on the geometry and echo information of a LiDAR point cloud. In order to overcome the shortcomings stemming from the inclusion of bare ground data before classification, the proposed classifier directly distinguishes terrain using a feature step-off count. Feature selection is conducted using JointBoost to evaluate feature correlations thus improving both classification accuracy and operational efficiency. In this paper, the contextual constraints for objects extracted by graph-cut segmentation are used to optimize the initial classification results obtained by the JointBoost classifier. Our experimental results show that the step-off count significantly contributes to classification. Seventeen effective features are selected for the initial classification results using the JointBoost classifier. Our experiments indicate that the proposed features and method are effective for classification of airborne LiDAR data from complex scenarios.

  9. Characterizing Englacial and Subglacial Temperature Structure Using Airborne Radar Sounding

    NASA Astrophysics Data System (ADS)

    Schroeder, D. M.; Seroussi, H. L.

    2015-12-01

    The temperature structure of ice sheet and glaciers is a fundamental control on ice flow, rheology, and stability. However, it is difficult to observationally constrain temperature structures at the catchment to ice-sheet scale. The englacial attenuation of radar sounding data is strongly dependent on the temperature structure of the ice sheets. Therefore, echo strength profiles from airborne radar sounding observation do contain temperature information. However, direct interpretation of englacial attenuation rates from radar sounding profiles is often difficult or impossible due to the ambiguous contribution the geometric and material properties of the bed to echo strength variations. To overcome this challenge, we presents techniques that treat radar sounding echo strength and ice thickness profiles as continuous signals, taking advantage of along-profile ice thickness and echo strength variations to constrain the spatial pattern of englacial attenuation and basal reflectivity. We then apply these techniques to an airborne radar sounding survey in order to characterize the englacial and subglacial temperature structure of the Thwaites Glacier catchment in West Antarctic. We then interpreted this structure in context of local ice sheet velocity, advection, force balance, and bed conditions using the ISSM ice sheet model.

  10. Airborne Systems Technology Application to the Windshear Threat

    NASA Technical Reports Server (NTRS)

    Arbuckle, P. Douglas; Lewis, Michael S.; Hinton, David A.

    1996-01-01

    The general approach and products of the NASA/FAA Airborne Windshear Program conducted by NASA Langley Research Center are summarized, with references provided for the major technical contributions. During this period, NASA conducted 2 years of flight testing to characterize forward-looking sensor performance. The NASA/FAA Airborne Windshear Program was divided into three main elements: Hazard Characterization, Sensor Technology, and Flight Management Systems. Simulation models developed under the Hazard Characterization element are correlated with flight test data. Flight test results comparing the performance and characteristics of the various Sensor Technologies (microwave radar, lidar, and infrared) are presented. Most of the activities in the Flight Management Systems element were conducted in simulation. Simulation results from a study evaluating windshear crew procedures and displays for forward-looking sensor-equipped airplanes are discussed. NASA Langley researchers participated heavily in the FAA process of generating certification guidelines for predictive windshear detection systems. NASA participants felt that more valuable technology products were generated by the program because of this interaction. NASA involvement in the process and the resulting impact on products and technology transfer are discussed in this paper.

  11. Polychlorinated Biphenyl (PCB) carcinogenicity with special emphasis on airborne PCBs

    PubMed Central

    Robertson, Larry W.; Ludewig, Gabriele

    2011-01-01

    Polychlorinated biphenyls (PCBs) are industrial chemicals used in various applications requiring chemical stabilityand have now become widely dispersed. Their characteristics of persistence, low water/higher lipid solubility, contribute to their ability to bioconcentrate and bioaccumulate. Traditionally PCBs have been regulated as food contaminants and the general population is primarily exposed by that route. PCBs in foodstuffs are generally higher chlorinated, resistant to metabolic breakdown, and elicit toxic changes that are thought to be predominantly receptor/parent PCB-driven. But for certain occupational exposures, and for those persons residing or working in contaminated buildings, and in large cities, an inhalation route of exposure may predominate. Airborne PCBs are, in contrast to foodborne PCBs, lower chlorinated, more volatile, and subject to metabolic attack. In this review, we have explored (geno-) toxic manifestations of PCBs typical of those found in air. Here metabolic conversion of the parent PCB to hydroxylated and other metabolic progeny appear to play a dominant role, especially in genotoxicity. We should be cognizant of the impact of exposures to airborne PCBs for those individuals who are occupationally exposed, for persons living near contaminated sites, for those who work or go to school in contaminated buildings, and especially cognizant of the young, the socio-economically disadvantaged and medically-underserved or nutritionally-deficient populations. PMID:21686028

  12. Airborne measurements of NO2 shipping emissions using imaging DOAS

    NASA Astrophysics Data System (ADS)

    Meier, Andreas C.; Schönhardt, Anja; Richter, Andreas; Seyler, André; Ruhtz, Thomas; Lindemann, Carsten; Wittrock, Folkard; Burrows, John P.

    2014-05-01

    NOx (NO and NO2) play a key role in tropospheric chemistry and affect human health and the environment. Shipping emissions contribute substantially to the global emissions of anthropogenic NOx. Due to globalization and increased trade volume, the relative importance emissions from ships gain even more importance. The Airborne imaging DOAS instrument for Measurements of Atmospheric Pollution (AirMAP), developed at IUP Bremen, has been used to perform measurements of NO2 in the visible spectral range. The observations allow the determination of spatial distributions of column densities of NO2 below the aircraft. Airborne measurements were performed over Northern Germany and adjacent coastal waters during the NOSE (NO2 from Shipping Emissions) campaign in August 2013. The focus of the campaign activities was on shipping emissions, but NO2 over cities and power plants has been measured as well. The measurements have a spatial resolution below the order of 100 × 30 m2, and they reveal the large spatial variability of NO2 and the evolution of NO2 plumes behind point sources. Shipping lanes as well as plumes of individual ships are detected by the AirMAP instrument. In this study, first results from the NOSE campaign are presented for selected measurement areas.

  13. Simulation Results for Airborne Precision Spacing along Continuous Descent Arrivals

    NASA Technical Reports Server (NTRS)

    Barmore, Bryan E.; Abbott, Terence S.; Capron, William R.; Baxley, Brian T.

    2008-01-01

    This paper describes the results of a fast-time simulation experiment and a high-fidelity simulator validation with merging streams of aircraft flying Continuous Descent Arrivals through generic airspace to a runway at Dallas-Ft Worth. Aircraft made small speed adjustments based on an airborne-based spacing algorithm, so as to arrive at the threshold exactly at the assigned time interval behind their Traffic-To-Follow. The 40 aircraft were initialized at different altitudes and speeds on one of four different routes, and then merged at different points and altitudes while flying Continuous Descent Arrivals. This merging and spacing using flight deck equipment and procedures to augment or implement Air Traffic Management directives is called Flight Deck-based Merging and Spacing, an important subset of a larger Airborne Precision Spacing functionality. This research indicates that Flight Deck-based Merging and Spacing initiated while at cruise altitude and well prior to the Terminal Radar Approach Control entry can significantly contribute to the delivery of aircraft at a specified interval to the runway threshold with a high degree of accuracy and at a reduced pilot workload. Furthermore, previously documented work has shown that using a Continuous Descent Arrival instead of a traditional step-down descent can save fuel, reduce noise, and reduce emissions. Research into Flight Deck-based Merging and Spacing is a cooperative effort between government and industry partners.

  14. Anthropogenic Osmium in Airborne Particles from Woods Hole, Massachusetts, USA

    NASA Astrophysics Data System (ADS)

    Peucker-Ehrenbrink, B.; Sen, I. S.; Geboy, N.

    2012-12-01

    The global geochemical cycle of osmium has been significantly disturbed by the introduction of automobile exhaust catalysts to convert noxious gas emissions into more benign forms. Anthropogenic osmium has been reported in rainwater, snow, and in the urban airborne particles from around the world to reveal global-scale osmium pollution [1, 2]. In this study, we report on the platinum group element (PGE) concentrations and osmium isotope ratios of airborne particles (PM10) collected in Woods Hole, a small coastal town in Massachusetts to better understand inputs of anthropogenic osmium to rural environments. We further investigate the use of osmium isotopes to track sources of airborne particles and support source apportionment studies on a continental scale. The samples used in this study were collected at Woods Hole Oceanographic Institution over one year (2008-2009). From this collection twelve samples for which the backward air mass trajectories have been determined were selected for osmium isotope analyses. Our results show that the osmium and platinum concentrations are an order of magnitude lower when compared to downtown Boston [2]. The average Os, Pt and Ir concentrations are 0.006±0.012, 0.019±0.023, and 0.685±0.634 pg m-3, respectively. The 187Os/188Os of the aerosols range from 0.275 to 0.788. As continental crust is radiogenic (187Os/188Os >1) and PGE ore bodies generally have unradiogenic 187Os/188Os (~0.2), the unradiogenic 187Os/188Os signature of the aerosols indicates anthropogenic contributions. With 95% of the total osmium mobilization on land being attributed to human activities [3], it is clear that human imprint on airborne particles is not restricted to urban centers with high traffic flows, but also affects rural environments. Aerosol particles that have backward air mass trajectories from the Southwest, the densely populated and industrialized Eastern seaboard, are characterized by unradiogenic osmium, while air masses from the North

  15. A new method for analysis of reactive adsorbed intermediates: Bismuth postdosing in thermal desorption mass spectroscopy

    NASA Astrophysics Data System (ADS)

    Campbell, Charles T.; Rodriguez, J. A.; Henn, F. C.; Campbell, J. M.; Dalton, P. J.; Seimanides, S. G.

    1988-05-01

    A new method which should have relatively general applicability for the identification and quantitative analysis of reactive adsorbed molecular intermediates in surface reactions will be described, and the first examples of its application will be presented. When a reactive intermediate is generated on a surface, it often has a tendency to dissociate before desorbing. Since dissociation generally requires additional free sites on the surface, dissociation can be suppressed and desorption correspondingly enhanced if the free sites on the surface can be properly poisoned. We have found that bismuth adatoms are very good inert site blockers, which can be postdosed to the surface of a transition metal containing a reactive adsorbed hydrocarbon without destroying the hydrocarbon. Whereas in the absence of bismuth, the hydrocarbon would completely dehydrogenate during thermal desorption spectroscopy (TDS) and liberate only H2 into the gas phase, after bismuth postdosing the reactive hydrocarbon desorbs intact for mass spectral identification and quantitative analysis. This method has been used to prove that adsorbed benzene is the initial product of the dehydrogenation of cyclohexane on Pt(111) at ˜235 K. In the absence of bismuth, this benzene all dissociates during TDS to liberate only H2, leaving graphitic carbon residue on the surface. When one-third monolayer of Bi is postdosed at 110 K, the dehydrogenation pathway is sterically poisoned and the adsorbed benzene quantitatively desorbs during TDS, where it is unambiguously identified by mass spectroscopy. By briefly heating the reactive adsorbed intermediate to increasing temperatures prior to Bi deposition, the thermal stability limits of the intermediate and the kinetic parameters for its dissociation can be established. This is demonstrated for the dehydrogenation reaction of adsorbed cyclopentene on Pt(111). Bismuth postdosing in thermal desorption mass spectroscopy (BPTDS) should be a very useful but

  16. Quantitative 3D Determination of Radiosensitization by Bismuth-Based Nanoparticles.

    PubMed

    Alqathami, Mamdooh; Blencowe, Anton; Geso, Moshi; Ibbott, Geoffrey

    2016-03-01

    The nanoparticle-induced dose enhancement effect has been shown to improve the therapeutic efficacy of ionizing radiation in external beam radiotherapy. Whereas previous studies have focused on gold nanoparticles (AuNPs), no quantitative studies have been conducted to investigate the potential superiority of other high atomic number (Z) nanomaterials such as bismuth-based nanoparticles. The aims of this study were to experimentally validate and quantify the dose enhancement properties of commercially available bismuth-based nanoparticles (bismuth oxide (Bi2O3-NPs) and bismuth sulfide (Bi2S3-NPs)), and investigate their potential superiority over AuNPs in terms of radiation dose enhancement. Phantom cuvettes doped with and without nanoparticles where employed for measuring radiation dose enhancement produced from the interaction of radiation with metal nanoparticles. Novel 3D phantoms were employed to investigate the 3D spatial distribution of ionising radiation dose deposition. The phantoms were irradiated with kilovoltage and megavoltage X-ray beams and optical absorption changes were measured using a spectrophotometer and optical CT scanner. The radiation dose enhancement factors (DEFs) obtained for 50 nm diameter Bi2O3-NPs and AuNPs were 1.90 and 1.77, respectively, for 100 kV energy and a nanoparticle concentration of 0.5 mM. In addition, the DEFs of 5 nm diameter Bi2S3-NPs and AuNPs were determined to be 1.38 and 1.51, respectively, for 150 kV energy and a nanoparticle concentration of 0.25 mM. The results demonstrate that both bismuth-based nanoparticles can enhance the effects of radiation. For 6 MV energy the DEFs for all the investigated nanoparticles were lower (< 15%) than with kilovoltage energy. PMID:27280244

  17. Dose reduction in CT using bismuth shielding: measurements and Monte Carlo simulations

    PubMed Central

    Chang, Kyung-Hwan; Lee, Wonho; Choo, Dong-Myung; Lee, Choon-Sik; Kim, Youhyun

    2010-01-01

    In this research, using direct measurements and Monte Carlo calculations, the potential dose reduction achieved by bismuth shielding in computed tomography was evaluated. The patient dose was measured using an ionisation chamber in a polymethylmethacrylate (PMMA) phantom that had five measurement points at the centre and periphery. Simulations were performed using the MCNPX code. For both the bare and the bismuth-shielded phantom, the differences of dose values between experiment and simulation were within 9 %. The dose reductions due to the bismuth shielding were 1.2–55 % depending on the measurement points, X-ray tube voltage and the type of shielding. The amount of dose reduction was significant for the positions covered by the bismuth shielding (34 − 46 % for head and 41 − 55 % for body phantom on average) and negligible for other peripheral positions. The artefact on the reconstructed images were minimal when the distance between the shielding and the organs was >1 cm, and hence the shielding should be selectively located to protect critical organs such as the eye lens, thyroid and breast. The simulation results using the PMMA phantom was compared with those using a realistically voxelised phantom (KTMAN-2). For eye and breast, the simulation results using the PMMA and KTMAN-2 phantoms were similar with each other, while for thyroid the simulation results were different due to the discrepancy of locations and the sizes of the phantoms. The dose reductions achieved by bismuth and lead shielding were compared with each other and the results showed that the difference of the dose reductions achieved by the two materials was less than 2–3 %. PMID:19959602

  18. Dose reduction in CT using bismuth shielding: measurements and Monte Carlo simulations.

    PubMed

    Chang, Kyung-Hwan; Lee, Wonho; Choo, Dong-Myung; Lee, Choon-Sik; Kim, Youhyun

    2010-03-01

    In this research, using direct measurements and Monte Carlo calculations, the potential dose reduction achieved by bismuth shielding in computed tomography was evaluated. The patient dose was measured using an ionisation chamber in a polymethylmethacrylate (PMMA) phantom that had five measurement points at the centre and periphery. Simulations were performed using the MCNPX code. For both the bare and the bismuth-shielded phantom, the differences of dose values between experiment and simulation were within 9%. The dose reductions due to the bismuth shielding were 1.2-55% depending on the measurement points, X-ray tube voltage and the type of shielding. The amount of dose reduction was significant for the positions covered by the bismuth shielding (34 - 46% for head and 41 - 55% for body phantom on average) and negligible for other peripheral positions. The artefact on the reconstructed images were minimal when the distance between the shielding and the organs was >1 cm, and hence the shielding should be selectively located to protect critical organs such as the eye lens, thyroid and breast. The simulation results using the PMMA phantom was compared with those using a realistically voxelised phantom (KTMAN-2). For eye and breast, the simulation results using the PMMA and KTMAN-2 phantoms were similar with each other, while for thyroid the simulation results were different due to the discrepancy of locations and the sizes of the phantoms. The dose reductions achieved by bismuth and lead shielding were compared with each other and the results showed that the difference of the dose reductions achieved by the two materials was less than 2-3%. PMID:19959602

  19. Near-infrared luminescence of bismuth in fluorine-doped-core silica fibres.

    PubMed

    Bazakutsa, A P; Golant, K M

    2015-02-01

    Photoluminescence spectra and decay kinetics of bismuth inclusions in silica optical fibres containing fluorine additive in the core glass are studied in the vicinity of a wavelength of 1420 nm at temperatures of 80-900 K under a continuous wave (CW) and a pulsed diode laser pump at a wavelength of 808 nm. At high fluorine concentration and low temperatures, luminescence decay kinetics becomes essentially bi-exponential, typical lifetimes being 720 and 1200 µs. Hydrogen and deuterium loading at pressures of up to 125 bar leads to a decrease of the steady-state luminescence intensity and lifetime. We attribute this to the appearance of an energy transfer bridge from bismuth clusters to vibrational degrees of freedom of diatomic molecules. It is found that in the presence of H(2) or D(2) molecules experiencing random walking in silica, luminescence decay kinetics stop following a single exponential function even in fluorine-free silica-core fibre, deviation from the single exponent being greater at higher temperatures. The induced quenching rate increases with the increase of temperature as well and is greater for H(2) molecules. All conditions being equal, the equilibrium concentration of hydrogen molecules is greater in heavily fluorinated silica. At temperatures below ~250 K, the presence of dissolved molecules has no effect, which speaks for the primary importance of having rotational degrees of freedom of migrating interstitial diatomic molecules in an excited state for effective quenching of bismuth electronic excitations. It is found that the influence of dissolved deuterium is weaker than that of hydrogen. We attribute this feature to a greater angular momentum of the D(2) molecule and correspondingly smaller energy of the molecule's rotational quantum. The results of the experiments show that bismuth clusters mainly located in voids of the silica network, rather than bismuth point defects, are responsible for near-infrared luminescence. PMID:25836233

  20. Approaches to detection of airborne biological agents

    NASA Astrophysics Data System (ADS)

    Chang, An-Cheng; Tabacco, Mary Beth

    2009-05-01

    Three approaches to detection of biological agents based on biological processes will be presented. The first example demonstrates the use of dendrimers to deliver a membrane-impermeable fluorescent dye into live bacteria, similar to viral infection and delivery of DNA/RNA into a bacterial cell. The second example mimics collection and capture of airborne biological particles by the respiratory mucosa through the use of a hygroscopic sensing membrane. The third example is based on the use of multiple fluorescent probes with diverse functionalities to detect airborne biological agents in a manner similar to the olfactory receptors in the nasal tract.