Science.gov

Sample records for air core light

  1. Scintillation dosimeter arrays using air core light guides: simulation and experiment.

    PubMed

    Naseri, Pourandokht; Suchowerska, Natalka; McKenzie, David R

    2010-06-21

    The performance of a scintillation dosimeter that uses a silvered air core light guide is examined by Monte Carlo (MC) simulations and by experiment to determine its suitability for array dosimetry in external beam radiotherapy. The air core light guide avoids the generation of the Cerenkov background that is produced in a conventional optical fibre. MC simulations using a 6 MV photon beam showed that silver thicknesses of less than 1 microm compensated for the effects of the other material components, to give the dosimeter water equivalence within 0.5%. A second dosimeter located adjacent to the primary dosimeter in any direction affected the dose measurement by less than 1.5%, when the centre-to-centre spacing was 1.3 mm or greater. When the dosimeter array is located perpendicular to the beam central axis, with a spacing of 2.5 mm, the calculated deviation from the dose deposited in water was less than 2%. When the dosimeter array is located parallel to the beam central axis with a spacing of 10 mm, the calculated dose readings deviated from water by less than 2.5%. The simulation results were confirmed with experiment for two neighbouring dosimeters and a small densely packed array. No proximity effects were measured within the experimental error of +/-1.5%. These results confirm the dosimetric accuracy of the air core dosimeter design without the need for correction factors. The dosimeter has excellent potential for use in arrays.

  2. Core Formation Process and Light Elements in the Planetary Core

    NASA Astrophysics Data System (ADS)

    Ohtani, E.; Sakairi, T.; Watanabe, K.; Kamada, S.; Sakamaki, T.; Hirao, N.

    2015-12-01

    Si, O, and S are major candidates for light elements in the planetary core. In the early stage of the planetary formation, the core formation started by percolation of the metallic liquid though silicate matrix because Fe-S-O and Fe-S-Si eutectic temperatures are significantly lower than the solidus of the silicates. Therefore, in the early stage of accretion of the planets, the eutectic liquid with S enrichment was formed and separated into the core by percolation. The major light element in the core at this stage will be sulfur. The internal pressure and temperature increased with the growth of the planets, and the metal component depleted in S was molten. The metallic melt contained both Si and O at high pressure in the deep magma ocean in the later stage. Thus, the core contains S, Si, and O in this stage of core formation. Partitioning experiments between solid and liquid metals indicate that S is partitioned into the liquid metal, whereas O is weakly into the liquid. Partitioning of Si changes with the metallic iron phases, i.e., fcc iron-alloy coexisting with the metallic liquid below 30 GPa is depleted in Si. Whereas hcp-Fe alloy above 30 GPa coexisting with the liquid favors Si. This contrast of Si partitioning provides remarkable difference in compositions of the solid inner core and liquid outer core among different terrestrial planets. Our melting experiments of the Fe-S-Si and Fe-O-S systems at high pressure indicate the core-adiabats in small planets, Mercury and Mars, are greater than the slope of the solidus and liquidus curves of these systems. Thus, in these planets, the core crystallized at the top of the liquid core and 'snowing core' formation occurred during crystallization. The solid inner core is depleted in both Si and S whereas the liquid outer core is relatively enriched in Si and S in these planets. On the other hand, the core adiabats in large planets, Earth and Venus, are smaller than the solidus and liquidus curves of the systems. The

  3. Investigation of residual core ellipticity induced nonreciprocity in air-core photonic bandgap fiber optical gyroscope.

    PubMed

    Xu, Xiaobin; Zhang, Zuchen; Zhang, Zhihao; Jin, Jing; Song, Ningfang

    2014-11-01

    Air-core photonic bandgap fiber (PBF) is an excellent choice for fiber optic gyroscope owing to its incomparable adaptability of environment. Strong and continuous polarization mode coupling is found in PBFs with an average intensity of ~-30 dB, but the coupling arrives at the limit when the maximum optical path difference between the primary waves and the polarization-mode-coupling-induced secondary waves reaches ~10mm, which is corresponding to the PBF length of ~110 m according to the birefringence in the PBF. Incident light with the low extinction ratio (ER) can suppress the birth of the polarization-mode-coupling-induced secondary waves, but the low-ER light obtained by the conventional Lyot depolarizers does not work here. Consequently, a large nonreciprocity and a bias error of ~13°/h are caused in the air-core photonic bandgap fiber optical gyroscope (PBFOG) with a PBF coil of ~268 m.

  4. Making Mercury's Core with Light Elements

    NASA Technical Reports Server (NTRS)

    Vander Kaaden, Kathleen E.; McCubbin, Francis M.; Ross, D. Kent

    2016-01-01

    Recent results obtained from the MErcury Surface, Space ENvironment, GEochemistry, and Ranging spacecraft showed the surface of Mercury has low FeO abundances (less than 2 wt%) and high S abundances (approximately 4 wt%), suggesting the oxygen fugacity of Mercury's surface materials is somewhere between 3 to 7 log10 units below the IW buffer. The highly reducing nature of Mercury has resulted in a relatively thin mantle and a large core that has the potential to exhibit an exotic composition in comparison to the other terrestrial planets. This exotic composition may extend to include light elements (e.g., Si, C, S). Furthermore, has argued for a possible primary floatation crust on Mercury composed of graphite, which may require a core that is C-saturated. In order to investigate mercurian core compositions, we conducted piston cylinder experiments at 1 GPa, from 1300 C to 1700 C, using a range of starting compositions consisting of various Si-Fe metal mixtures (Si5Fe95, Si10Fe90, Si22Fe78, and Si35Fe65). All metals were loaded into graphite capsules used to ensure C-saturation during the duration of each experimental run. Our experiments show that Fe-Si metallic alloys exclude carbon relative to more Fe-rich metal. This exclusion of carbon commences within the range of 5 to 10 wt% Si. These results indicate that if Mercury has a Si-rich core (having more than approximately 5 wt% silicon), it would have saturated in carbon at low C abundances allowing for the possible formation of a graphite floatation crust as suggested by. These results have important implications for the thermal and magmatic evolution of Mercury.

  5. Flexible liquid core light guide with focusing and light shaping attachments

    DOEpatents

    Kross, B.J.; Majewski, S.; Zorn, C.J.; Majewski, L.A.

    1997-11-04

    A liquid light guide system for ultraviolet light is disclosed that has a light shaping arrangement for the emitted light, a stable liquid core and sheath and reliable and effective end closures. 12 figs.

  6. Model-based parameterisation of a hydrocyclone air-core

    PubMed

    Podd; Schlaberg; Hoyle

    2000-03-01

    An important metric for the accurate control of a hydrocyclone is the diameter of its air-core. Ultrasonic data from a 16-transducer, 1.5 MHz pulse-echo tomographic system are analysed to determine the variation of the air-core diameter with various operating conditions. The back-projection image reconstruction method is not accurate enough for this task. Sub-millimetre accuracy is obtained, however, by applying a combination of signal processing and model-based reconstruction, using the fact that there is a small variation in the air-core boundary position. The findings correspond well to the results obtained from X-ray and electrical resistance modalities.

  7. Reconfigurable optothermal microparticle trap in air-filled hollow-core photonic crystal fiber.

    PubMed

    Schmidt, O A; Garbos, M K; Euser, T G; Russell, P St J

    2012-07-13

    We report a novel optothermal trapping mechanism that occurs in air-filled hollow-core photonic crystal fiber. In the confined environment of the core, the motion of a laser-guided particle is strongly influenced by the thermal-gradient-driven flow of air along the core surface. Known as "thermal creep flow," this can be induced either statically by local heating, or dynamically by the absorption (at a black mark placed on the fiber surface) of light scattered by the moving particle. The optothermal force on the particle, which can be accurately measured in hollow-core fiber by balancing it against the radiation forces, turns out to exceed the conventional thermophoretic force by 2 orders of magnitude. The system makes it possible to measure pN-scale forces accurately and to explore thermally driven flow in micron-scale structures. PMID:23030165

  8. Flexible, liquid core light guide with focusing and light shaping attachments

    DOEpatents

    Wojcik, Randolph Frank; Majewski, Stanislaw; Zorn, Carl John; Kross, Brian

    1999-01-01

    A liquid light guide system for ultraviolet light is disclosed that has a light shaping arrangement for the emitted light, a stable liquid core and sheath and reliable and effective end closures. The end closures include a metal crimping arrangement that utilizes two layers of deformable materials to prevent cracking of endplugs.

  9. Flexible, liquid core light guide with focusing and light shaping attachments

    DOEpatents

    Wojcik, R.F.; Majewski, S.; Zorn, C.J.; Kross, B.

    1999-04-20

    A liquid light guide system for ultraviolet light is disclosed that has a light shaping arrangement for the emitted light, a stable liquid core and sheath and reliable and effective end closures. The end closures include a metal crimping arrangement that utilizes two layers of deformable materials to prevent cracking of endplugs. 19 figs.

  10. Experimental constraints on light elements in the Earth's outer core.

    PubMed

    Zhang, Youjun; Sekine, Toshimori; He, Hongliang; Yu, Yin; Liu, Fusheng; Zhang, Mingjian

    2016-01-01

    Earth's outer core is liquid and dominantly composed of iron and nickel (~5-10 wt%). Its density, however, is ~8% lower than that of liquid iron, and requires the presence of a significant amount of light element(s). A good way to specify the light element(s) is a direct comparison of density and sound velocity measurements between seismological data and those of possible candidate compositions at the core conditions. We report the sound velocity measurements of a model core composition in the Fe-Ni-Si system at the outer core conditions by shock-wave experiments. Combining with the previous studies, we found that the best estimate for the outer core's light elements is ~6 wt% Si, ~2 wt% S, and possible ~1-2.5 wt% O. This composition satisfies the requirements imposed by seismology, geochemistry, and some models of the early core formation. This finding may help us to further constrain the thermal structure of the Earth and the models of Earth's core formation. PMID:26932596

  11. Experimental constraints on light elements in the Earth's outer core.

    PubMed

    Zhang, Youjun; Sekine, Toshimori; He, Hongliang; Yu, Yin; Liu, Fusheng; Zhang, Mingjian

    2016-03-02

    Earth's outer core is liquid and dominantly composed of iron and nickel (~5-10 wt%). Its density, however, is ~8% lower than that of liquid iron, and requires the presence of a significant amount of light element(s). A good way to specify the light element(s) is a direct comparison of density and sound velocity measurements between seismological data and those of possible candidate compositions at the core conditions. We report the sound velocity measurements of a model core composition in the Fe-Ni-Si system at the outer core conditions by shock-wave experiments. Combining with the previous studies, we found that the best estimate for the outer core's light elements is ~6 wt% Si, ~2 wt% S, and possible ~1-2.5 wt% O. This composition satisfies the requirements imposed by seismology, geochemistry, and some models of the early core formation. This finding may help us to further constrain the thermal structure of the Earth and the models of Earth's core formation.

  12. Technical Issues Associated with Air Ingression During Core Degradation

    SciTech Connect

    POWERS,DANA A.

    2000-06-05

    This paper has shown that it is possible to get significant air intrusion into a ruptured reactor vessel even from a reactor cavity with restricted access. This suggests that there is some importance to considering the consequences of air intrusion following vessel penetration by core debris. The consequences will depend on the nature of core degradation in air and other oxidizing gases. If, indeed, fuel becomes exposed to strongly oxidizing gases, significant releases of ruthenium and hexavalent urania can be expected. Hexavalent urania could alter the nature of cesium release and cesium revaporization from the reactor coolant system. Hexavalent urania could destabilize CSI and enhance the formation of gaseous iodine unless there are other materials that will react readily with atomic iodine along the flow path to the reactor containment.

  13. Character of energy flow in air shower core

    NASA Technical Reports Server (NTRS)

    Mizushima, K.; Asakimori, K.; Maeda, T.; Kameda, T.; Misaki, Y.

    1985-01-01

    Energy per charged particle near the core of air showers was measured by 9 energy flow detectors, which were the combination of Cerenkov counters and scintillators. Energy per particle of each detector was normalized to energy at 2m from the core. The following results were obtained as to the energy flow: (1) integral frequency distribution of mean energy per particle (averaged over 9 detectors) is composed of two groups separated distinctly; and (2) showers contained in one group show an anisotropy of arrival direction.

  14. High-voltage air-core pulse transformers

    SciTech Connect

    Rohwein, G.J.

    1981-08-01

    High voltage air core pulse transformers are best suited to applications outside the normal ranges of conventional magnetic core transformers. In general these include charge transfer at high power levels and fast pulse generation with comparatively low energy. When properly designed and constructed, they are capable of delivering high energy transfer efficiency and have demonstrated superior high voltage endurance. The general types designed for high voltage pulse generation and energy transfer applications are described. Special emphasis is given to pulse charging systems which operate up to the multi-megavolt range. (WHK)

  15. ElectroCore separator for particulate air emissions

    SciTech Connect

    Easom, B.H.; Smolensky, L.A.; Wysk, S.R.; Altman, R.F.; Olen, K.R.

    1998-07-01

    Coal combustion in fossil energy power systems releases trace amounts of chemical elements identified in the Clean Air Act Amendments of 1990 as hazardous air pollutants (HAPs). Most HAPs exist as solid phase particulate matter and are emitted to the atmosphere in this form. To reduce the emissions of these HAPs, a novel, high efficiency particle collection system known as the ElectroCore is being developed. The concept involves placing a high efficiency particle separator downstream of an underperforming electrostatic precipitator (ESP) that strips the particles from the incoming flow and returns them, along with a small amount of recirculation flow, back to the inlet of the ESP. The main component of the system is the ElectroCore separator. Its design is based on the mechanical Core Separator developed by LSR as a high efficiency centrifugal separator. Enhancing the Core Separator by adding an electrical field improves the separation efficiency of particles in the sub-micron range which is the range where centrifugal separation is ineffective. In the combined system, the centrifugal forces operating on the particles augmented by electrostatic forces so that the ElectroCore has high separation efficiency for particles of all sizes. Field tests have shown that the ElectroCore operating downstream of an underperforming ESP can reduce the particulate emission rate to below 4.3 ng/J (0.01 lb{sub m}/million Btu) even for ESPs with emission rates as high as 260 ng/J (0.6 lb{sub m}/million Btu). The ElectroCore system can perform with most all coal ranks or residual fuel oils (RFO) and has a potentially low capital cost.

  16. Bolometric and UV light curves of core-collapse supernovae

    SciTech Connect

    Pritchard, T. A.; Roming, P. W. A.; Brown, Peter J.; Bayless, Amanda J.; Frey, Lucille H.

    2014-06-01

    The Swift UV-Optical Telescope (UVOT) has been observing core-collapse supernovae (CCSNe) of all subtypes in the UV and optical since 2005. Here we present 50 CCSNe observed with the Swift UVOT, analyzing their UV properties and behavior. Where we have multiple UV detections in all three UV filters (λ {sub c} = 1928-2600 Å), we generate early time bolometric light curves, analyze the properties of these light curves and the UV contribution to them, and derive empirical corrections for the UV-flux contribution to optical-IR based bolometric light curves.

  17. Light, Colour & Air Quality: Important Elements of the Learning Environment?

    ERIC Educational Resources Information Center

    Hathaway, Warren E.

    1987-01-01

    Reviews and evaluates studies of the effects of light, color, and air quality on the learning environment. Concludes that studies suggest a role for light in establishing and maintaining physiological functions and balances and a need for improved air quality in airtight, energy efficient buildings. (JHZ)

  18. OPTICAL COLORS OF INTRACLUSTER LIGHT IN THE VIRGO CLUSTER CORE

    SciTech Connect

    Rudick, Craig S.; Mihos, J. Christopher; Harding, Paul; Morrison, Heather L.; Feldmeier, John J.; Janowiecki, Steven

    2010-09-01

    We continue our deep optical imaging survey of the Virgo cluster using the CWRU Burrell Schmidt telescope by presenting B-band surface photometry of the core of the Virgo cluster in order to study the cluster's intracluster light (ICL). We find ICL features down to {mu}{sub B} {approx}29 mag arcsec{sup -2}, confirming the results of Mihos et al., who saw a vast web of low surface brightness streams, arcs, plumes, and diffuse light in the Virgo cluster core using V-band imaging. By combining these two data sets, we are able to measure the optical colors of many of the cluster's low surface brightness features. While much of our imaging area is contaminated by galactic cirrus, the cluster core near the cD galaxy, M87, is unobscured. We trace the color profile of M87 out to over 2000'', and find a blueing trend with radius, continuing out to the largest radii. Moreover, we have measured the colors of several ICL features which extend beyond M87's outermost reaches and find that they have similar colors to the M87's halo itself, B - V {approx}0.8. The common colors of these features suggest that the extended outer envelopes of cD galaxies, such as M87, may be formed from similar streams, created by tidal interactions within the cluster, that have since dissolved into a smooth background in the cluster potential.

  19. Air-core grid for scattered x-ray rejection

    DOEpatents

    Logan, C.M.; Lane, S.M.

    1995-10-03

    The invention is directed to a grid used in x-ray imaging applications to block scattered radiation while allowing the desired imaging radiation to pass through, and to process for making the grid. The grid is composed of glass containing lead oxide, and eliminates the spacer material used in prior known grids, and is therefore, an air-core grid. The glass is arranged in a pattern so that a large fraction of the area is open allowing the imaging radiation to pass through. A small pore size is used and the grid has a thickness chosen to provide high scatter rejection. For example, the grid may be produced with a 200 {micro}m pore size, 80% open area, and 4 mm thickness. 2 figs.

  20. Air-core grid for scattered x-ray rejection

    DOEpatents

    Logan, Clinton M.; Lane, Stephen M.

    1995-01-01

    The invention is directed to a grid used in x-ray imaging applications to block scattered radiation while allowing the desired imaging radiation to pass through, and to process for making the grid. The grid is composed of glass containing lead oxide, and eliminates the spacer material used in prior known grids, and is therefore, an air-core grid. The glass is arranged in a pattern so that a large fraction of the area is open allowing the imaging radiation to pass through. A small pore size is used and the grid has a thickness chosen to provide high scatter rejection. For example, the grid may be produced with a 200 .mu.m pore size, 80% open area, and 4 mm thickness.

  1. Core testing of zinc/air refuelable battery modules

    SciTech Connect

    Cooper, J. F., LLNL

    1998-08-20

    We are developing a refuelable zinc/air battery (6-cells) for evaluation under the five USABC `core` test protocols. In the first half of the two year project ($1OOK, FY1997), an advanced refuelable design was developed, fabricated and tested at power levels up to 415 W. Performance matched or exceeded that of earlier multicell systems. A computer program was developed for automated data acquisition and drive cycle simulation. Small mockup cells (80 cm 2) were constructed for rapid testing of components. In the follow-on effort (FY1998, $1OOK) we will make minor advances in system design and fabrication efficiency, and seek to improve cathode performance and life, before delivery of two final units for test at DOE laboratory.

  2. EMPACT: Electrons Muons Partons with Air Core Toroids

    SciTech Connect

    Marx, M.D. )

    1990-05-25

    The EMPACT experiment utilizes a broad approach to maximize its discovery potential for new phenomena accessible at the SSC. The high resolution detector has a balances emphasis on, and large acceptance for, electrons, muons, jets, and noninteracting particles, and is capable of utilizing the ultimate luminosity of the SSC. The detector emphasizes excellent calorimetry augmented by TRD tracking, and employs an innovative system of superconducting air core toroids for muon measurements. Significant engineering effort has established the feasibility of a baseline detector concept and has addressed the related issues of support facilities, assembly, and detector integration. The design has been tested against the challenges of predicted phenomena, with the expectation that this will optimize the capacity for observing the unexpected. EMPACT's international collaboration has unprecedented support from major aerospace industries who are providing tools and expertise for project design and integration, which will assure that a detector optimized for performance and cost will be available for the first collisions at the new laboratory.

  3. Microtube Light-Emitting Diode Arrays with Metal Cores.

    PubMed

    Tchoe, Youngbin; Lee, Chul-Ho; Park, Jun Beom; Baek, Hyeonjun; Chung, Kunook; Jo, Janghyun; Kim, Miyoung; Yi, Gyu-Chul

    2016-03-22

    We report the fabrication and characteristics of vertical microtube light-emitting diode (LED) arrays with a metal core inside the devices. To make the LEDs, gallium nitride (GaN)/indium gallium nitride (In(x)Ga(1-x)N)/zinc oxide (ZnO) coaxial microtube LED arrays were grown on an n-GaN/c-aluminum oxide (Al2O3) substrate. The microtube LED arrays were then lifted-off the substrate by wet chemical etching of the sacrificial ZnO microtubes and the silicon dioxide (SiO2) layer. The chemically lifted-off LED layer was then transferred upside-down on other supporting substrates. To create the metal cores, titanium/gold and indium tin oxide were deposited on the inner shells of the microtubes, forming n-type electrodes inside the metal-cored LEDs. The characteristics of the resulting devices were determined by measuring electroluminescence and current-voltage characteristic curves. To gain insights into the current-spreading characteristics of the devices and understand how to make them more efficient, we modeled them computationally. PMID:26855251

  4. Microtube Light-Emitting Diode Arrays with Metal Cores.

    PubMed

    Tchoe, Youngbin; Lee, Chul-Ho; Park, Jun Beom; Baek, Hyeonjun; Chung, Kunook; Jo, Janghyun; Kim, Miyoung; Yi, Gyu-Chul

    2016-03-22

    We report the fabrication and characteristics of vertical microtube light-emitting diode (LED) arrays with a metal core inside the devices. To make the LEDs, gallium nitride (GaN)/indium gallium nitride (In(x)Ga(1-x)N)/zinc oxide (ZnO) coaxial microtube LED arrays were grown on an n-GaN/c-aluminum oxide (Al2O3) substrate. The microtube LED arrays were then lifted-off the substrate by wet chemical etching of the sacrificial ZnO microtubes and the silicon dioxide (SiO2) layer. The chemically lifted-off LED layer was then transferred upside-down on other supporting substrates. To create the metal cores, titanium/gold and indium tin oxide were deposited on the inner shells of the microtubes, forming n-type electrodes inside the metal-cored LEDs. The characteristics of the resulting devices were determined by measuring electroluminescence and current-voltage characteristic curves. To gain insights into the current-spreading characteristics of the devices and understand how to make them more efficient, we modeled them computationally.

  5. AIRS-Light Instrument Concept and Critical Technology Development

    NASA Technical Reports Server (NTRS)

    Maschhoff, Kevin

    2001-01-01

    Understanding Earth's climate, atmospheric transport mechanisms, and the hydrologic cycle requires a precise knowledge of global atmospheric circulation, temperature profiles, and water vapor distribution. The accuracy of advanced sounders such as AIRS/AMSU/HSB on NASA's Aqua spacecraft can match radiosonde accuracy. It is essential to fold those capabilities fully into the NPOESS, enabling soundings of radiosonde accuracy, every 6 hours around the globe on an operational basis. However, the size, mass, power demands, and thermal characteristics of the Aqua sounding instrument suite cannot be accommodated on the NPOESS spacecraft. AIRS-Light is an instrument concept, developed under the Instrument Incubator Program, which provides IR sounding performance identical to the AIRS instrument, but uses advances in HgCdTe FPA technology and pulse tube cooler technology, as well as design changes to dramatically reduce the size, mass, and power demand, allowing AIRS-Light to meet all NPOESS spacecraft interface requirements. The instrument concept includes substantial re-use of AIRS component designs, including the complex AIRS FPA, to reduce development risk and cost. The AIRS-Light Instrument Incubator program fostered the development of photovoltaic-mode HgCdTe detector array technology for the 13.5-15.4 micron band covered by photoconductive-mode HgCdTe arrays in AIRS, achieved state of the art results in this band, and substantially reduced the development risk for this last new technology needed for AIRS-Light implementation, A demonstration of a prototype 14.5-15.4 micron band IRFPA in a reduced heat-load dewar together with the IMAS pulse tube cryocooler is in progress.

  6. Light bullets from Mid-IR femtosecond filament in air

    NASA Astrophysics Data System (ADS)

    Smetanina, E. O.; Fedorov, V. Yu; Dormidonov, A. E.; Kandidov, V. P.

    2014-10-01

    We numerically investigated the formation of light bullets under filamentation of 3.8- μm femtosecond pulse in presence of anomalous GVD in humid air. The dispersion of humid air in infrared spectral region was characterized by model fits of the real part of refractive index from HITRAN database. The fit for the 2.8-4.2 μm region describes the areas of anomalous GVD near 3.1 μm and 4 μm in humid air. During the nonlinear propagation of femtosecond pulse in humid air, the compressed in space and time wave packet - light bullet - appears in the central time layers of the pulse and moves to the pulse tail. The duration of light bullet reaches the few-cycle value and the energy fluence in the in the light bullet cross-section is above 1 J/cm2. Together with the light bullet formation the spectrum of the pulse broadens strongly and covers the spectral region from 3 μm to 5 μm. The interference model was used for investigation of the frequency-angular distribution of the supercontinuum spectrum components.

  7. Advanced light microscopy core facilities: Balancing service, science and career.

    PubMed

    Ferrando-May, Elisa; Hartmann, Hella; Reymann, Jürgen; Ansari, Nariman; Utz, Nadine; Fried, Hans-Ulrich; Kukat, Christian; Peychl, Jan; Liebig, Christian; Terjung, Stefan; Laketa, Vibor; Sporbert, Anje; Weidtkamp-Peters, Stefanie; Schauss, Astrid; Zuschratter, Werner; Avilov, Sergiy

    2016-06-01

    Core Facilities (CF) for advanced light microscopy (ALM) have become indispensable support units for research in the life sciences. Their organizational structure and technical characteristics are quite diverse, although the tasks they pursue and the services they offer are similar. Therefore, throughout Europe, scientists from ALM-CFs are forming networks to promote interactions and discuss best practice models. Here, we present recommendations for ALM-CF operations elaborated by the workgroups of the German network of ALM-CFs, German Bio-Imaging (GerBI). We address technical aspects of CF planning and instrument maintainance, give advice on the organization and management of an ALM-CF, propose a scheme for the training of CF users, and provide an overview of current resources for image processing and analysis. Further, we elaborate on the new challenges and opportunities for professional development and careers created by CFs. While some information specifically refers to the German academic system, most of the content of this article is of general interest for CFs in the life sciences. Microsc. Res. Tech. 79:463-479, 2016. © 2016 THE AUTHORS MICROSCOPY RESEARCH AND TECHNIQUE PUBLISHED BY WILEY PERIODICALS, INC. PMID:27040755

  8. Advanced light microscopy core facilities: Balancing service, science and career.

    PubMed

    Ferrando-May, Elisa; Hartmann, Hella; Reymann, Jürgen; Ansari, Nariman; Utz, Nadine; Fried, Hans-Ulrich; Kukat, Christian; Peychl, Jan; Liebig, Christian; Terjung, Stefan; Laketa, Vibor; Sporbert, Anje; Weidtkamp-Peters, Stefanie; Schauss, Astrid; Zuschratter, Werner; Avilov, Sergiy

    2016-06-01

    Core Facilities (CF) for advanced light microscopy (ALM) have become indispensable support units for research in the life sciences. Their organizational structure and technical characteristics are quite diverse, although the tasks they pursue and the services they offer are similar. Therefore, throughout Europe, scientists from ALM-CFs are forming networks to promote interactions and discuss best practice models. Here, we present recommendations for ALM-CF operations elaborated by the workgroups of the German network of ALM-CFs, German Bio-Imaging (GerBI). We address technical aspects of CF planning and instrument maintainance, give advice on the organization and management of an ALM-CF, propose a scheme for the training of CF users, and provide an overview of current resources for image processing and analysis. Further, we elaborate on the new challenges and opportunities for professional development and careers created by CFs. While some information specifically refers to the German academic system, most of the content of this article is of general interest for CFs in the life sciences. Microsc. Res. Tech. 79:463-479, 2016. © 2016 THE AUTHORS MICROSCOPY RESEARCH AND TECHNIQUE PUBLISHED BY WILEY PERIODICALS, INC.

  9. Advanced light microscopy core facilities: Balancing service, science and career

    PubMed Central

    Hartmann, Hella; Reymann, Jürgen; Ansari, Nariman; Utz, Nadine; Fried, Hans‐Ulrich; Kukat, Christian; Peychl, Jan; Liebig, Christian; Terjung, Stefan; Laketa, Vibor; Sporbert, Anje; Weidtkamp‐Peters, Stefanie; Schauss, Astrid; Zuschratter, Werner; Avilov, Sergiy

    2016-01-01

    ABSTRACT Core Facilities (CF) for advanced light microscopy (ALM) have become indispensable support units for research in the life sciences. Their organizational structure and technical characteristics are quite diverse, although the tasks they pursue and the services they offer are similar. Therefore, throughout Europe, scientists from ALM‐CFs are forming networks to promote interactions and discuss best practice models. Here, we present recommendations for ALM‐CF operations elaborated by the workgroups of the German network of ALM‐CFs, German Bio‐Imaging (GerBI). We address technical aspects of CF planning and instrument maintainance, give advice on the organization and management of an ALM‐CF, propose a scheme for the training of CF users, and provide an overview of current resources for image processing and analysis. Further, we elaborate on the new challenges and opportunities for professional development and careers created by CFs. While some information specifically refers to the German academic system, most of the content of this article is of general interest for CFs in the life sciences. Microsc. Res. Tech. 79:463–479, 2016. © 2016 THE AUTHORS MICROSCOPY RESEARCH AND TECHNIQUE PUBLISHED BY WILEY PERIODICALS, INC. PMID:27040755

  10. Wireline-rotary air coring of the Bandelier Tuff, Los Alamos, New Mexico

    USGS Publications Warehouse

    Teasdale, W.E.; Pemberton, R.R.

    1984-01-01

    This paper describes experiments using wireline-rotary air-coring techniques conducted in the Bandelier Tuff using a modified standard wireline core-barrel system. The modified equipment was used to collect uncontaminated cores of unconsolidated ash and indurated tuff at Los Alamos, New Mexico. Core recovery obtained from the 210-foot deep test hole was about 92 percent. A standard HQ-size, triple-tube wireline core barrel (designed for the passage of liquid drilling fluids) was modified for air coring as follows: (1) Air passages were milled in the latch body part of the head assembly; (2) the inside dimension of the outer core barrel tube was machined and honed to provide greater clearance between the inner and outer barrels; (3) oversized reaming devices were added to the outer core barrel and the coring bit to allow more clearance for air and cuttings return; (4) the eight discharge ports in the coring bit were enlarged. To control airborne-dust pollution, a dust-and-cuttings discharge subassembly, designed and built by project personnel, was used. (USGS)

  11. Power supply with air core transformer and seperated power supplies for high dynamic range

    NASA Technical Reports Server (NTRS)

    Chutjian, Ara (Inventor); Aalami, Dean (Inventor); Darrach, Murray (Inventor); Orient, Otto (Inventor)

    2001-01-01

    A power supply for a quadrupole mass spectrometer which operates using an RF signal. The RF signal is controllable via a feedback loop. The feedback loop is from the output, through a comparator, and compared to a digital signal. An air core transformer is used to minimize the weight. The air core transformer is driven via two out of phase sawtooth signals which drive opposite ends of the transformer.

  12. Post-coring entrapment of modern air in polar ice: Evidence from CFC-12 measurements in Antarctic firn air and shallow ice cores

    NASA Astrophysics Data System (ADS)

    Aydin, K. M.; Montzka, S. A.; Battle, M. O.; Williams, M. B.; de Bruyn, W. J.; Butler, J. H.; Verhulst, K. R.; Tatum, C.; Gun, B. K.; Plotkin, D. A.; Hall, B. D.; Saltzman, E. S.

    2009-12-01

    This study is a comparison of CFC-12 (CCl2F2) measurements in firn air and ice core samples from three Antarctic sites: South Pole, West Antarctic Ice Sheet Divide (79.46°S, 112.13°W), and Siple Dome (81.65°S, 148.81°W). CFC-12 is a synthetic chlorofluorocarbon manufactured during the mid-late 20th century for use as a refrigerant and an aerosol spray propellant. Its atmospheric history is well established with agreement among instrumental time series measurements and industry-reported production data [Walker et al., 2000], the distribution of dissolved CFC-12 in the oceans [e.g. Weiss et al., 1985], and firn air measurements [Butler et al., 1999]. The atmospheric history indicates that there was no measureable CFC-12 in the atmosphere prior to the 1940’s. The firn air CFC-12 profiles are consistent with the known atmospheric history of this gas. In contrast, the air in ice core samples collected near the close-off depth exhibit anomalously high CFC-12 levels. We propose that this is due to entrapment of modern air in open pores that close after drilling, resulting in elevated CFC-12 mixing ratios. These results demonstrate how the composition of air trapped in shallow ice cores can be altered during the post-drilling period through purely physical processes. Comparison of firn air and ice core bubble composition is one of the commonly used tools for studying the bubble close-off process. The post-drilling entrapment process detected in this study represents a potential complication for such investigations.

  13. Amateur scientists - producing light from a bubble of air

    SciTech Connect

    Hiller, R.A.; Barber, B.P.

    1995-02-01

    A glowing bubble of air cannot be bought anywhere at any price. But with an oscilloscope, a moderately precise sound generator, a home stereo amplifier and about $100, readers can turn sound into light through a process called sonoluminescence. The apparatus is relatively simple. A glass spherical flask filled with water serves as the resonator - the cavity in which sound is created to trap and drive the bubble. Small speakers, called piezoelectric transducers, are cemented to the flask and powered by an audo generator and amplifier. Bubbles introduced into the water coalesce at the center of the flask and produce a dim light visible to the unaided eye in a darkened room.

  14. Controlled interactions of femtosecond light filaments in air

    SciTech Connect

    Shim, Bonggu; Schrauth, Samuel E.; Hensley, Christopher J.; Vuong, Luat T.; Hui, Pui; Ishaaya, Amiel A.; Gaeta, Alexander L.

    2010-06-15

    We experimentally demonstrate coherent control of two light filaments in air generated by ultrafast laser pulses, as proposed by Xi et al. [Phys. Rev. Lett. 96, 025003 (2006)]. We show that depending on the relative phase and the incidence angle, the filaments can experience fusion, repulsion, energy redistribution, and spiral motion for propagation in air. By translating the initial beams on subwavelength scales, we achieve {approx}1-mm transverse deflection of approximately 0.5-mJ energy for parallel propagation and 7 deg. angular deflection for spiral motion in 3-m propagation. Our approach using the relative beam phases to reliably control propagation of femtosecond light filaments is potentially applicable to remote sensing and lightning guiding.

  15. The Yucca Mountain Project prototype air-coring test, U12g tunnel, Nevada test site

    SciTech Connect

    Ray, J.M.; Newsom, J.C.

    1994-12-01

    The Prototype Air-Coring Test was conducted at the Nevada Test Site (NTS) G-Tunnel facility to evaluate standard coring techniques, modified slightly for air circulation, for use in testing at a prospective nuclear waste repository at Yucca Mountain, Nevada. Air-coring technology allows sampling of subsurface lithology with minimal perturbation to ambient characteristic such as that required for exploratory holes near aquifers, environmental applications, and site characterization work. Two horizontal holes were cored, one 50 ft long and the other 150 ft long, in densely welded fractured tuff to simulate the difficult drilling conditions anticipated at Yucca Mountain. Drilling data from seven holes on three other prototype tests in nonwelded tuff were also collected for comparison. The test was used to establish preliminary standards of performance for drilling and dust collection equipment and to assess procedural efficiencies. The Longyear-38 drill achieved 97% recovery for HQ-size core (-2.5 in.), and the Atlas Copco dust collector (DCT-90) captured 1500 lb of fugitive dust in a mine environment with only minor modifications. Average hole production rates were 6-8 ft per 6-h shift in welded tuff and almost 20 ft per shift on deeper holes in nonwelded tuff. Lexan liners were successfully used to encapsulate core samples during the coring process and protect core properties effectively. The Prototype Air-Coring Test demonstrated that horizontal air coring in fractured welded tuff (to at least 150 ft) can be safely accomplished by proper selection, integration, and minor modification of standard drilling equipment, using appropriate procedures and engineering controls. The test also indicated that rig logistics, equipment, and methods need improvement before attempting a large-scale dry drilling program at Yucca Mountain.

  16. Optical refractometer based on large-core air-clad photonic crystal fibers.

    PubMed

    Silva, Susana; Santos, J L; Malcata, F Xavier; Kobelke, Jens; Schuster, Kay; Frazão, O

    2011-03-15

    A large-core air-clad photonic crystal fiber-based sensing structure is described, which is sensitive to refractive index. The sensing head is based on multimodal interference, and relies on a single-mode/large-core air-clad photonic crystal fiber (PCF)/single-mode fiber configuration. Using two distinct large-core air-clad PCF geometries-one for refractive index measurement and the other for temperature compensation, it was possible to implement a sensing head sensitive to refractive index changes in water as induced by temperature variations. The results indicated the high sensitivity of this sensing head to refractive index variations of water, and a resolution of 3.4×10(-5) refractive index units could be achieved. PMID:21403706

  17. Robust near-infrared light bullet in 800-nm femtosecond light filaments in air

    NASA Astrophysics Data System (ADS)

    Panov, Nikolay A.; Shipilo, Daniil E.; Andreeva, Vera A.; Uryupina, Daria S.; Savel'ev, Andrei B.; Kosareva, Olga G.; Chin, See Leang

    2015-09-01

    Systematic numerical study of near-infrared radiation formed during filamentation in air revealed the formation of robust light bullet first registered in the experiment (Chen et al. in Appl Phys B 91:219, 2008). The near-infrared light bullet propagates along the filament axis with the divergence <1 mrad and the quasi-constant duration of ~30 fs. The central wavelength of the bullet gradually increases from 860 to 900 nm during the propagation. The results of our numerical simulation are in agreement with the experiments (Chen et al. in Appl Phys B 91:219, 2008; Uryupina et al. in Appl Phys B 110:123, 2013).

  18. Spontaneous Rayleigh-Brillouin scattering of ultraviolet light in nitrogen, dry air, and moist air.

    PubMed

    Witschas, Benjamin; Vieitez, Maria O; van Duijn, Eric-Jan; Reitebuch, Oliver; van de Water, Willem; Ubachs, Wim

    2010-08-01

    Atmospheric lidar techniques for the measurement of wind, temperature, and optical properties of aerosols rely on the exact knowledge of the spectral line shape of the scattered laser light on molecules. We report on spontaneous Rayleigh-Brillouin scattering measurements in the ultraviolet at a scattering angle of 90 degrees on N(2) and on dry and moist air. The measured line shapes are compared to the Tenti S6 model, which is shown to describe the scattering line shapes in air at atmospheric pressures with small but significant deviations. We demonstrate that the line profiles of N(2) and air under equal pressure and temperature conditions differ significantly, and that this difference can be described by the S6 model. Moreover, we show that even a high water vapor content in air up to a volume fraction of 3.6vol.% has no influence on the line shape of the scattered light. The results are of relevance for the future spaceborne lidars on ADM-Aeolus (Atmospheric Dynamics Mission) and EarthCARE (Earth Clouds, Aerosols, and Radiation Explorer). PMID:20676176

  19. Spontaneous Rayleigh-Brillouin scattering of ultraviolet light in nitrogen, dry air, and moist air.

    PubMed

    Witschas, Benjamin; Vieitez, Maria O; van Duijn, Eric-Jan; Reitebuch, Oliver; van de Water, Willem; Ubachs, Wim

    2010-08-01

    Atmospheric lidar techniques for the measurement of wind, temperature, and optical properties of aerosols rely on the exact knowledge of the spectral line shape of the scattered laser light on molecules. We report on spontaneous Rayleigh-Brillouin scattering measurements in the ultraviolet at a scattering angle of 90 degrees on N(2) and on dry and moist air. The measured line shapes are compared to the Tenti S6 model, which is shown to describe the scattering line shapes in air at atmospheric pressures with small but significant deviations. We demonstrate that the line profiles of N(2) and air under equal pressure and temperature conditions differ significantly, and that this difference can be described by the S6 model. Moreover, we show that even a high water vapor content in air up to a volume fraction of 3.6vol.% has no influence on the line shape of the scattered light. The results are of relevance for the future spaceborne lidars on ADM-Aeolus (Atmospheric Dynamics Mission) and EarthCARE (Earth Clouds, Aerosols, and Radiation Explorer).

  20. Termination of light-water reactor core-melt accidents with a chemical core catcher: the core-melt source reduction system (COMSORS)

    SciTech Connect

    Forsberg, C.W.; Parker, G.W.; Rudolph, J.C.; Osborne-Lee, I.W.; Kenton, M.A.

    1996-09-01

    The Core-Melt Source Reduction System (COMSORS) is a new approach to terminate light-water reactor core melt accidents and ensure containment integrity. A special dissolution glass is placed under the reactor vessel. If core debris is released onto the glass, the glass melts and the debris dissolves into the molten glass, thus creating a homogeneous molten glass. The molten glass, with dissolved core debris, spreads into a wide pool, distributing the heat for removal by radiation to the reactor cavity above or by transfer to water on top of the molten glass. Expected equilibrium glass temperatures are approximately 600 degrees C. The creation of a low-temperature, homogeneous molten glass with known geometry permits cooling of the glass without threatening containment integrity. This report describes the technology, initial experiments to measure key glass properties, and modeling of COMSORS operations.

  1. Determination of radiocarbon in stratospheric CO2, obtained through AirCore sampling.

    NASA Astrophysics Data System (ADS)

    Paul, Dipayan; Chen, Huilin; Been, Henk A.; Kivi, Rigel; Meijer, Harro A. J.

    2016-04-01

    The concentration of Greenhouse Gases (GHG), with carbon dioxide as the most prominent example, has been and still is increasing, predominantly due to emissions from fossil fuel combustion. CO2 is also the most important component of the global carbon cycle. Among other tracers, radiocarbon (Carbon-14) is a unique and an important atmospheric tracer used in the understanding of the global carbon cycle. Radiocarbon is a naturally occurring isotope (radioactive, t 1/2 = 5730 ± 40 years) of carbon produced through the interaction of thermalized neutrons and nitrogen in the upper atmosphere. Generally, for performing atmospheric radiocarbon measurements in the higher atmosphere, large samples (few liters of air) were collected using aircrafts and balloons. However, collecting stratospheric samples on a regular basis for radiocarbon analysis is extremely expensive. Here we describe the determination of radiocarbon concentrations in stratospheric CO2, collected using AirCore sampling. AirCore is an innovative sampling technique for obtaining vertical atmospheric profiles and, in Europe, is done on a regular basis at Sodankylä, Finland for CO2, CH4 and CO. The stratospheric parts of two such AirCore profiles were used in this study as a proof-of-principle. CO2 from the stratospheric air samples were extracted and converted to elemental carbon, which were then measured at the Accelerator Mass Spectrometric (AMS) facility of the Centre for Isotope Research (CIO) at the University of Groningen. The stratospheric part of the AirCore profile was divided into six sections, each contained approximately 10 μg C. A detailed description of the extraction, graphitization, AMS analysis and the derivation of the stratospheric radiocarbon profile will be the main focus. Through our results, we will show that AirCore is a viable sampling method for performing high-precision radiocarbon measurements of stratospheric CO2 with reasonably good spatial resolution on a regular basis

  2. Effects of light intensity light quality and air velocity on temperature in plant reproductive organs

    NASA Astrophysics Data System (ADS)

    Kitaya, Y.; Hirai, H.

    Excess temperature increase in plant reproductive organs such as anthers and stigmata could cause fertility impediments and thus produce sterile seeds under artificial lighting conditions in closed plant growth facilities There is a possibility that the aberration was caused by an excess increase in temperatures of reproductive organs in Bioregenerative Life Support Systems under microgravity conditions in space The fundamental study was conducted to know the thermal situation of the plant reproductive organs as affected by light intensity light quality and air velocity on the earth and to estimate the excess temperature increase in the reproductive organs in closed plant growth facilities in space Thermal images of reproductive organs of rice and strawberry were captured using infrared thermography at an air temperature of 10 r C The temperatures in flowers at 300 mu mol m -2 s -1 PPFD under the lights from red LEDs white LEDs blue LEDs fluorescent lamps and incandescent lamps increased by 1 4 1 7 1 9 6 0 and 25 3 r C respectively for rice and by 2 8 3 4 4 1 7 8 and 43 4 r C respectively for strawberry The flower temperatures increased with increasing PPFD levels The temperatures in petals anthers and stigmas of strawberry at 300 mu mol m -2 s -1 PPFD under incandescent lamps increased by 32 7 29 0 and 26 6 r C respectively at 0 1 m s -1 air velocity and by 20 6 18 5 and 15 9 r C respectively at 0 8 m s -1 air velocity The temperatures of reproductive organs decreased with increasing

  3. Air-ring microstructure arrays for enhanced light extraction from a face-up light-emitting diode.

    PubMed

    Kim, Hyun Kyu; Park, Young Jae; Kang, Ji Hye; Han, Nam; Han, Min; Ryu, Beo Deul; Ko, Kang Bok; Yang, Jong Han; Kim, Young Taek; Chandramohan, S; Jeong, Hyun; Jeong, Mun Seok; Hong, Chang-Hee

    2013-05-01

    In this Letter, a light-emitting diode (LED) with prism-shaped-air-ring microstructures (PSAMs) formed on flat sapphire substrate is demonstrated as an alternative design to face-up LEDs on patterned sapphire substrate (PSS) for enhanced light extraction efficiency. In this LED design, the emitted photons can be deflected to the top of the chip for its effective extraction, contrary to the PSS-LED wherein photons are guided to sapphire and get absorbed by packaging materials. The PSAM-LED showed an enhancement in the radiometric power as high as 10% with a low far-field angle of 129° over that of a PSS-LED under an injection current of 20 mA. PMID:23632528

  4. The Effects of Very Light Jet Air Taxi Operations on Commercial Air Traffic

    NASA Technical Reports Server (NTRS)

    Smith, Jeremy C.; Dollyhigh, Samuel M.

    2006-01-01

    This study investigates the potential effects of Very Light Jet (VLJ) air taxi operations adding to delays experienced by commercial passenger air transportation in the year 2025. The affordable cost relative to existing business jets and ability to use many of the existing small, minimally equipped, but conveniently located airports is projected to stimulate a large demand for the aircraft. The resulting increase in air traffic operations will mainly be at smaller airports, but this study indicates that VLJs have the potential to increase further the pressure of demand at some medium and large airports, some of which are already operating at or near capacity at peak times. The additional delays to commercial passenger air transportation due to VLJ air taxi operations are obtained from simulation results using the Airspace Concepts Evaluation System (ACES) simulator. The direct increase in operating cost due to additional delays is estimated. VLJs will also cause an increase in traffic density, and this study shows increased potential for conflicts due to VLJ operations.

  5. AIRS First Light Data: Eastern Mediterranean, June 14, 2002

    NASA Technical Reports Server (NTRS)

    2002-01-01

    [figure removed for brevity, see original site] [figure removed for brevity, see original site] Figure 1Figure 2Figure 3

    Four images of the Mediterranean obtained concurrently on June 14, 2002 from the three instruments that make up the Atmospheric Infrared Sounder experiment system aboard NASA's Aqua spacecraft. The system features thousands of individual channels that observe Earth in the visible, infrared and microwave spectral regions. Each channel has a unique sensitivity to temperature, moisture, surface conditions and clouds.

    This visible light image from the AIRS instrument shows a band of white clouds extending from the Adriatic Sea over Greece to the Black Sea.

    The AIRS image (figure 1) at 900 cm-1 (11 micrometers) measures actual surface or cloud top temperatures. In it, land and ocean boundaries are well defined, with land appearing as warmer (darker red) than the ocean. The band of cold high cumulus clouds appears blue, with the darkest blue most likely a large thunderstorm.

    The 150 gigahertz channel from the Humidity Sounder for Brazil instrument (figure 2) is sensitive to moisture, ice particles and precipitation. The dry land temperature is comparable to the 11 micrometer temperatures, but over ocean this channel measures the temperature of moisture in the mid troposphere. The cold, blue areas off Sicily and in the Aegean Sea represent unusually dry areas over the ocean. There, clouds appear as green filaments--likely areas of precipitation.

    The 31.4 gigahertz channel from the Advanced Microwave Sounding Unit instrument (figure 3) is not affected by clouds.

    NASA's Atmospheric Infrared Sounder (AIRS) onboard NASA's Aqua spacecraft, began sending high quality data on June 12, 2002. This 'first light' data is exceeding the expectations of scientists, confirming that the AIRS experiment is well on its way to meeting its goals of improving weather forecasting, establishing the connection between severe weather and

  6. Mid-stratospheric measurements of CO2, CH4, and CO using AirCore

    NASA Astrophysics Data System (ADS)

    Chen, H.; Karion, A.; Newberger, T.; Sweeney, C.; Andrews, A. E.; Tans, P. P.

    2011-12-01

    AirCore, a long tube descending from a high altitude with one end open and the other closed, has been demonstrated to be a reliable, cost-effective sampling system for CO2 and CH4 measurements. Previous studies show that vertical profiles from the ground level up to ~ 20 km (~ 40 mbar) can be achieved during a balloon flight. The ceiling of the profile is restricted mainly by the diffusion of air in the AirCore and the resolution of the analyzer used for the analysis. Here air with an extremely high CO mixing ratio (~ 10 ppm) has been employed as the initial fill air in the AirCore. This high CO fill gas is used as a label to track the mixing between sampled air and fill air at the top of the profile thus providing the ability to retrieve full profiles for CO2 and CH4 up to the balloon's ceiling height of ~ 30 km (~ 11 mbar). Stratospheric measurements of CO lack agreement among previous studies, (i.e. cryogenic sampling, in-situ measurements, and remote sensing) due to difficulties that are inherent to the various techniques and possibly due to latitudinal and seasonal variations that could not be represented by the available sparse observations. Efforts to collect an accurate profile of stratospheric CO using the AirCore, are complicated by the reaction of CO and O3 in the coil, which is particular important for stratospheric air with high O3. To remove the influence of O3 on the CO measurements from AirCore, we have investigated three O3 scrubbers: 1) Manganese dioxide (MnO2); 2) Sodium Sulfite (Na2SO3); 3) Sodium thiosulfate (Na2S2O3). Laboratory tests reveal that Sodium thiosulfate is the best choice as it has sufficient capacity to absorb O3 and does not impact measurements of CO2 and CH4. We will show experimental results from both aircraft and balloon flights. Regular ongoing stratospheric profiles of CO2, CH4, and CO are necessary to improve and validate total column measurements by remote sensing techniques, such as FTS and satellite. Such measurements

  7. Reflection-induced bias error in an air-core photonic bandgap fiber optic gyroscope.

    PubMed

    Zhang, Zuchen; Xu, Xiaobin; Zhang, Zhihao; Song, Ningfang; Zhang, Chunxi

    2016-01-15

    Analysis of the bias error induced by reflections in an air-core photonic bandgap fiber gyroscope is performed by both simulation and experiment. The bias error is sinusoidally periodic under modulation, and its intensity is related to the relative positions of the reflection points. A simple and effective method for the suppression of the error is proposed, and it has been verified experimentally.

  8. Intraoperative Core Temperature Patterns, Transfusion Requirement, and Hospital Duration in Patients Warmed with Forced Air

    PubMed Central

    Sun, Zhuo; Honar, Hooman; Sessler, Daniel I.; Dalton, Jarrod E.; Yang, Dongsheng; Panjasawatwong, Krit; Deroee, Armin F.; Salmasi, Vafi; Saager, Leif; Kurz, Andrea

    2015-01-01

    Background Core temperature patterns in patients warmed with forced-air remain poorly characterized. Also unknown is the extent to which transient and mild intraoperative hypothermia contributes to adverse outcomes in broad populations. Methods We evaluated esophageal (core) temperatures in 58,814 adults having surgery lasting >60 min who were warmed with forced air. Independent associations between hypothermic exposure and transfusion requirement and duration of hospitalization was evaluated. Results In every percentile subgroup, core temperature decreased during the first hour and subsequently increased. The mean lowest core temperature during the first hour was 35.7 ± 0.6°C. Sixty-four percent of the patients reached a core temperature threshold of <36°C 45 min after induction; 29% reached a core temperature threshold of <35.5°C. Nearly half the patients had continuous core temperatures <36°C for more than an hour, and 20% of the patients were <35.5°C for more than an hour. Twenty percent of patients had continuous core temperatures <36°C for more than 2 h, and 8% of the patients were below 35.5°C for more than 2 h. Hypothermia was independently associated with both transfusion and duration of hospitalization, although prolongation of hospitalization was small. Conclusions Even in actively warmed patients, hypothermia is routine in the first hour of anesthesia. Thereafter, average core temperatures progressively increase. Nonetheless, intraoperative hypothermia was common, and often prolonged. Hypothermia was associated with increased transfusion requirement which is consistent with numerous randomized trials. PMID:25603202

  9. Effects of diurnal bright/dim light intensity on circadian core temperature and activity rhythms in the Japanese macaque.

    PubMed

    Takasu, Nana; Nigi, Hideo; Tokura, Hiromi

    2002-12-01

    Circadian rhythms of core temperature and activity were studied using three Japanese macaques under influences of two different light intensities during the daytime. Nocturnal core temperature and activity onset time were lower and advanced, respectively, in bright as compared to dim light. These results suggest the possibility that diurnal bright light could influence the circadian organization.

  10. Experimental constraints on light elements in the Earth’s outer core

    PubMed Central

    Zhang, Youjun; Sekine, Toshimori; He, Hongliang; Yu, Yin; Liu, Fusheng; Zhang, Mingjian

    2016-01-01

    Earth’s outer core is liquid and dominantly composed of iron and nickel (~5–10 wt%). Its density, however, is ~8% lower than that of liquid iron, and requires the presence of a significant amount of light element(s). A good way to specify the light element(s) is a direct comparison of density and sound velocity measurements between seismological data and those of possible candidate compositions at the core conditions. We report the sound velocity measurements of a model core composition in the Fe-Ni-Si system at the outer core conditions by shock-wave experiments. Combining with the previous studies, we found that the best estimate for the outer core’s light elements is ~6 wt% Si, ~2 wt% S, and possible ~1–2.5 wt% O. This composition satisfies the requirements imposed by seismology, geochemistry, and some models of the early core formation. This finding may help us to further constrain the thermal structure of the Earth and the models of Earth’s core formation. PMID:26932596

  11. Illuminating light-dependent color shifts in core and veneer layers of dental all-ceramics

    NASA Astrophysics Data System (ADS)

    Lee, Yong-Keun; Cha, Hyun-Suk; Yu, Bin

    2014-09-01

    The color of an object is perceived differently depending on the ambient light conditions. Since dental all-ceramic restorations are fabricated by building up several layers to reproduce the tooth shade, the optical properties of each layer should be optimized for successful shade reproduction. This study aimed to determine the separate contributions of the color shifts in each of the core and veneer layers of all-ceramics by switching the illuminating lights on the color shifts of layered ceramics. Specimens of seven kinds of core ceramics and the corresponding veneer ceramics for each core were fabricated with a layered thickness of 1.5 mm. A sintering ceramic was used as a reference core material. The Commission Internationale de l'Eclairage (CIE) color coordinates of core, veneer, and layered specimens were measured with a spectroradiometer under the CIE illuminant D65 (daylight), A (incandescent lamp), and F9 (fluorescent lamp) simulating lights. Color shifts of the layered specimens were primarily determined by the CIE a* shifts (D65 to A switch) or by the CIE b* shifts (D65 to F9 switch) of the veneer layer. The color coordinates shifts in the constituent layers differentially influenced those of the layered specimens by the kind of switched lights. Therefore, the optical properties of the constituent layers of all-ceramics should be controlled to reflect these findings.

  12. Illuminating light-dependent color shifts in core and veneer layers of dental all-ceramics.

    PubMed

    Lee, Yong-Keun; Cha, Hyun-Suk; Yu, Bin

    2014-09-01

    The color of an object is perceived differently depending on the ambient light conditions. Since dental all-ceramic restorations are fabricated by building up several layers to reproduce the tooth shade, the optical properties of each layer should be optimized for successful shade reproduction. This study aimed to determine the separate contributions of the color shifts in each of the core and veneer layers of all-ceramics by switching the illuminating lights on the color shifts of layered ceramics. Specimens of seven kinds of core ceramics and the corresponding veneer ceramics for each core were fabricated with a layered thickness of 1.5 mm. A sintering ceramic was used as a reference core material. The Commission Internationale de l’Eclairage (CIE) color coordinates of core, veneer, and layered specimens were measured with a spectroradiometer under the CIE illuminant D65 (daylight), A (incandescent lamp), and F9 (fluorescent lamp) simulating lights. Color shifts of the layered specimens were primarily determined by the CIE a shifts (D65 to A switch) or by the CIE b shifts (D65 to F9 switch) of the veneer layer. The color coordinates shifts in the constituent layers differentially influenced those of the layered specimens by the kind of switched lights. Therefore, the optical properties of the constituent layers of all-ceramics should be controlled to reflect these findings.

  13. A stratified layer of light elements at the top of the outer core

    NASA Astrophysics Data System (ADS)

    McDonough, W. F.; Buffett, B. A.; Cormier, V. F.; Cottaar, S.; Day, E. A.; Dou, S.; French, S. W.; Irving, J. C.; Kavner, A.; Panning, M. P.; Parai, R.; Rose, I.

    2010-12-01

    seismic observables, and to include in geodynamic calculations. In addition, a series of sensitivity tests are performed, taking into account ranges of uncertainties in the mineral physics parameters. Through geodynamical modeling we investigate more completely the sensitivity of such a light layer to the model parameters, as well as coupling it with a more realistic model of core thermal evolution and inner core formation. By testing various end-members of initial conditions and parameters, we place bounds on the size of the layer and identify the regions of parameter space that would permit and exclude seismological observation of a stratified layer.

  14. Appearance of light clusters in post-bounce evolution of core-collapse supernovae

    SciTech Connect

    Sumiyoshi, Kohsuke; Roepke, Gerd

    2008-05-15

    We explore the abundance of light clusters in core-collapse supernovae at post-bounce stage in a quantum statistical approach. Adopting the profile of a supernova core from detailed numerical simulations, we study the distribution of light bound clusters up to {alpha} particles (2{<=}A{<=}4) as well as heavy nuclei (A>4) in dense matter at finite temperature. Within the frame of a cluster-mean-field approach, the abundances of light clusters are evaluated accounting for self-energy, Pauli blocking, and effects of continuum correlations. We find that deuterons and tritons, in addition to {sup 3}He and {sup 4}He, appear abundantly in a wide region from the surface of the proto-neutron star to the position of the shock wave. The appearance of light clusters may modify the neutrino emission in the cooling region and the neutrino absorption in the heating region and, thereby, influence the supernova mechanism.

  15. Chemical signals of past climate and environment from polar ice cores and firn air.

    PubMed

    Wolff, Eric W

    2012-10-01

    Chemical and isotopic records obtained from polar ice cores have provided some of the most iconic datasets in Earth system science. Here, I discuss how the different records are formed in the ice sheets, emphasising in particular the contrast between chemistry held in the snow/ice phase, and that which is trapped in air bubbles. Air diffusing slowly through the upper firn layers of the ice sheet can also be sampled in large volumes to give more recent historical information on atmospheric composition. The chemical and geophysical issues that have to be solved to interpret ice core data in terms of atmospheric composition and emission changes are also highlighted. Ice cores and firn air have provided particularly strong evidence about recent changes (last few decades to centuries), including otherwise inaccessible data on increases in compounds that are active as greenhouse gases or as agents of stratospheric depletion. On longer timescales (up to 800,000 years in Antarctica), ice cores reveal major changes in biogeochemical cycling, which acted as feedbacks on the very major changes in climate between glacial and interglacial periods.

  16. Radiocarbon analysis of stratospheric CO2 retrieved from AirCore sampling

    NASA Astrophysics Data System (ADS)

    Paul, Dipayan; Chen, Huilin; Been, Henk A.; Kivi, Rigel; Meijer, Harro A. J.

    2016-10-01

    Radiocarbon (14C) is an important atmospheric tracer and one of the many used in the understanding of the global carbon budget, which includes the greenhouse gases CO2 and CH4. Measurement of radiocarbon in atmospheric CO2 generally requires the collection of large air samples (a few liters) from which CO2 is extracted and then the concentration of radiocarbon is determined using accelerator mass spectrometry (AMS). However, the regular collection of air samples from the stratosphere, for example using aircraft and balloons, is prohibitively expensive. Here we describe radiocarbon measurements in stratospheric CO2 collected by the AirCore sampling method. AirCore is an innovative atmospheric sampling system, which comprises a long tube descending from a high altitude with one end open and the other closed, and it has been demonstrated to be a reliable, cost-effective sampling system for high-altitude profile (up to ≈ 30 km) measurements of CH4 and CO2. In Europe, AirCore measurements have been being performed on a regular basis near Sodankylä (northern Finland) since September 2013. Here we describe the analysis of samples from two such AirCore flights made there in July 2014, for determining the radiocarbon concentration in stratospheric CO2. The two AirCore profiles were collected on consecutive days. The stratospheric part of the AirCore was divided into six sections, each containing ≈ 35 µg CO2 ( ≈ 9.6 µgC), and stored in a stratospheric air subsampler constructed from 1/4 in. coiled stainless steel tubing ( ≈ 3 m). A small-volume extraction system was constructed that enabled > 99.5 % CO2 extraction from the stratospheric air samples. Additionally, a new small-volume high-efficiency graphitization system was constructed for graphitization of these extracted CO2 samples, which were measured at the Groningen AMS facility. Since the stratospheric samples were very similar in mass, reference samples were also prepared in the same mass range for

  17. Infrasonic acoustic waves generated by fast air heating in sprite cores

    NASA Astrophysics Data System (ADS)

    Silva, Caitano L.; Pasko, Victor P.

    2014-03-01

    Acceleration, expansion, and branching of sprite streamers can lead to concentration of high electrical currents in regions of space, that are observed in the form of bright sprite cores. Driven by this electrical current, a series of chemical processes take place in the sprite plasma. Excitation, followed by quenching of excited electronic states leads to energy transfer from charged to neutral species. The consequence is heating and expansion of air leading to emission of infrasonic acoustic waves. Results indicate that ≳0.01 Pa pressure perturbations on the ground, observed in association with sprites, can only be produced by exceptionally strong currents in sprite cores, exceeding 2 kA.

  18. Orbital tuning of deep ice cores using O2/N2 of trapped air

    NASA Astrophysics Data System (ADS)

    Kawamura, K.; Aoki, S.; Nakazawa, T.

    2014-12-01

    The chronology of the first Dome Fuji deep ice core (80,000-340,000 yr BP) was established by orbital tuning of measured O2/N2 ratios in trapped air to the past local summer insolation at the drill site (Kawamura et al., 2007). The O2/N2 ratios found in ice cores are generally lower than atmospheric ratio because of size-dependent molecular fractionation during bubble close-off. The magnitude of this gas fractionation appears to be influenced by snow metamorphism when the layer was originally at the surface, which in turn is controlled by local summer insolation (Fujita et al., 2009). The O2/N2 record has little 100,000-yr periodicity (strongest in climatic records), suggesting insignificant climatic influence in the orbital tuning. Agreement of the O2/N2 chronology with U-Th radiometric chronology of speleothems (within ~2000 yr) suggests that O2/N2 and summer insolation are indeed in phase. However, it may not be common to all ice cores that O2/N2 signal only records local summer insolation. For example, the GISP2 ice core (Greenland) has clear imprint of abrupt climate changes in the O2/N2 record, indicating climatic (non-insolation) signal in the record and the possibility of phase variability of O2/N2 relative to the past insolation (Suwa and Bender, 2008). Here we present new O2/N2 record from the second Dome Fuji ice core with significant improvements in ice core storage practice and mass spectrometry. In particular, the ice core had been stored at about -50 ˚C until the air extraction except during transportations, which prevent fractionation due to gas loss during the core storage. The precision of the new O2/N2 data set is improved by a factor of 3 over the previous data, and we do not observe outliers (there were 15% outliers in the previous data). Clear imprint of local insolation is recognizable in the new O2/N2, which would enable us to generate a chronology with accuracy of ~2000 yr towards older periods. Samples from the first core after long

  19. Benchmark calculation of no-core Monte Carlo shell model in light nuclei

    SciTech Connect

    Abe, T.; Shimizu, N.; Maris, P.; Vary, J. P.; Otsuka, T.; Utsuno, Y.

    2011-05-06

    The Monte Carlo shell model is firstly applied to the calculation of the no-core shell model in light nuclei. The results are compared with those of the full configuration interaction. The agreements between them are within a few % at most.

  20. Light source design using Kagome-lattice hollow core photonic crystal fibers

    NASA Astrophysics Data System (ADS)

    Hossain, Md. Anwar; Namihira, Yoshinori

    2014-09-01

    Supercontinuum (SC) light source is designed using high pressure Xe-filled hollow core Kagome-lattice photonic crystal fiber. Using finite element method with perfectly matched layer, SC spectra in normal chromatic dispersion region have been generated using picosecond optical pulses from relatively less expensive laser sources.

  1. Photoresponsive Cyanostilbene Bent-Core Liquid Crystals as New Materials with Light-Driven Modulated Polarization.

    PubMed

    Martínez-Abadía, Marta; Robles-Hernández, Beatriz; de la Fuente, María Rosario; Giménez, Raquel; Ros, Maria Blanca

    2016-08-01

    Two isomeric cyanostilbene photoswitchable bent-core mesogens with polar liquid crystal phases in which macroscopic polarization and luminescence can be light-modulated are introduced. Z/E isomerization or [2+2] cycloaddition photochemical processes occur depending on the chemical structure, which make the compounds very innovative multifunctional advanced materials.

  2. PF coil voltage optimization for start-up scenarios in air core tokamaks

    SciTech Connect

    Albanese, R.; Martone, R.; Ambrosino, G.; Pironti, A.

    1994-09-01

    The basic features of a procedure for the optimization of the plasma scenario in an air core tokamak are presented. The method takes into account the eddy currents in the passive conducting structures. The problem is reduced to the synthesis of time-varying magnetic field. The solution of this inverse electromagnetic problem is carried out by means of an optimization procedure based on the receding horizon approach. The paper includes an example of application to the ITER tokamak.

  3. Reflection-induced bias error in an air-core photonic bandgap fiber optic gyroscope.

    PubMed

    Zhang, Zuchen; Xu, Xiaobin; Zhang, Zhihao; Song, Ningfang; Zhang, Chunxi

    2016-01-15

    Analysis of the bias error induced by reflections in an air-core photonic bandgap fiber gyroscope is performed by both simulation and experiment. The bias error is sinusoidally periodic under modulation, and its intensity is related to the relative positions of the reflection points. A simple and effective method for the suppression of the error is proposed, and it has been verified experimentally. PMID:26766701

  4. Air core poloidal magnetic field system for a toroidal plasma producing device

    DOEpatents

    Marcus, Frederick B.

    1978-01-01

    A poloidal magnetics system for a plasma producing device of toroidal configuration is provided that reduces both the total volt-seconds requirement and the magnitude of the field change at the toroidal field coils. The system utilizes an air core transformer wound between the toroidal field (TF) coils and the major axis outside the TF coils. Electric current in the primary windings of this transformer is distributed and the magnetic flux returned by air core windings wrapped outside the toroidal field coils. A shield winding that is closely coupled to the plasma carries a current equal and opposite to the plasma current. This winding provides the shielding function and in addition serves in a fashion similar to a driven conducting shell to provide the equilibrium vertical field for the plasma. The shield winding is in series with a power supply and a decoupling coil located outside the TF coil at the primary winding locations. The present invention requires much less energy than the usual air core transformer and is capable of substantially shielding the toroidal field coils from poloidal field flux.

  5. Air bubble migration rates as a proxy for bubble pressure distribution in ice cores

    NASA Astrophysics Data System (ADS)

    Dadic, Ruzica; Schneebeli, Martin; Bertler, Nancy

    2015-04-01

    Air bubble migration can be used as a proxy to measure the pressure of individual bubbles and can help constrain the gradual close-off of gas bubbles and the resulting age distribution of gases in ice cores. The close-off depth of single bubbles can vary by tens of meters, which leads to a distribution of pressures for bubbles at a given depth. The age distribution of gases (along with gas-age-ice-age differences) decreases the resolution of the gas level reconstructions from ice cores and limits our ability to determine the phase relationship between gas and ice, and thus, the impact of rapid changes of greenhouse gases on surface temperatures. For times of rapid climate change, including the last 150 years, and abrupt climate changes further back in the past, knowledge of the age distribution of the gases trapped in air bubbles will enable us to refine estimates of atmospheric changes. When a temperature gradient is applied to gas bubbles in an ice sample, the bubbles migrate toward warmer ice. This motion is caused by sublimation from the warm wall and subsequent frost deposition on the cold wall. The migration rate depends on ice temperature and bubble pressure and is proportional to the temperature gradient. The spread in migration rates for bubbles in the same samples at given temperatures should therefore reflect the variations in bubble pressures within a sample. Air bubbles with higher pressures would have been closed off higher in the firn column and thus have had time to equilibrate with the surrounding ice pressure, while air bubbles that have been closed off recently would have pressures that are similar to todays atmospheric pressure above the firn column. For ice under pressures up to ~13-16 bar, the pressure distribution of bubbles from a single depth provides a record of the trapping function of air bubbles in the firn column for a certain time in the past. We will present laboratory experiments on air bubble migration, using Antarctic ice core

  6. What Can Neutrinos Tell Us about Light Elements in Earth's Core?

    NASA Astrophysics Data System (ADS)

    Li, J.; Dye, S.; Enomoto, S.

    2014-12-01

    The light element composition of the Earth's core remains mysterious despite decades' of research. Without any direct samples, our knowledge of the core composition has relied on a diversity of constraints including the density and velocity profiles derived from seismic and geophysical observations, the composition models proposed on the basis of geochemical and cosmochemical measurements, the material properties determined by mineral physics investigations, and the thermal and dynamo requirements coming out of dynamic modeling. The leading candidates for the principal light element include hydrogen, carbon, oxygen, sulfur and silicon, in the order of increasing atomic number. While each candidate stands out in some aspects and raises questions in others, none has been universally accepted as the dominant light element in the core. The controversy arises partly because the properties and behavior of various iron-alloys at extreme pressure and temperature conditions have not been fully constrained. It is also conceivable that existing approaches will not produce unique solution, and therefore requires new strategies. Neutrino oscillation tomography has recently emerged as a promising technique to probe the composition of Earth's interior. Neutrinos are produced in the atmosphere by cosmic ray interactions. Atmospheric neutrinos pass through the Earth's mantle and core, with flavor oscillations being affected by the electron density of the medium along the trajectories. The unique sensitivity of the atmospheric neutrinos to electron density introduces a contrast between hydrogen, which has a higher electron density, and carbon, oxygen, sulfur, and silicon, which have lower and similar electron densities. With sufficient exposure to an appropriate energy range, atmospheric neutrino measurements may allow us to detect the presence of the core and measure its radius. Here we compare electron densities of candidate model compositions of Earth's core and estimate the

  7. Perforated hollow core waveguides for Alkali Vapor-cells and Slow Light Devices

    NASA Astrophysics Data System (ADS)

    Giraud-Carrier, Matthieu C.

    The focus of this work is the integration of alkali vapor atomic vapor cells into common silicon wafer microfabrication processes. Such integrated platforms enable the study of quantum coherence effects such as electromagnetically induced transparency, which can in turn be used to demonstrate slow light. Slow and stopped light devices have applications in the optical communications and quantum computing fields. This project uses hollow core anti-resonant reflecting optical waveguides (ARROWs) to build such slow light devices. An explanation of light-matter interactions and the physics of slow light is first provided, as well as a detailed overview of the fabrication process. Following the discovery of a vapor transport issue, a custom capillary-based testing platform is developed to quantify the effect of confinement, temperature, and wall coatings on rubidium transport. A mathematical model is derived from the experimental results and predicts long transport times. A new design methodology is presented that addresses the transport problem by increasing the number of rubidium entry points. This design also improves chip durability and decreases environmental susceptibility through the use of a single copper reservoir and buried channel waveguides (BCWs). New chips are successfully fabricated, loaded, and monitored for rubidium spectra. Absorption is observed in several chips and absorption peaks depths in excess of 10% are reported. The chip lifetime remains comparable to previous designs. This new design can be expanded to a multi-core platform suitable for slow and stopped light experimentation. Keywords: Matthieu Giraud-Carrier, Aaron Hawkins, microfabrication, spectroscopy, slow light, stopped light, EIT, rubidium, diffusion, vapor transport, microfabrication, ARROW, light-matter interactions, waveguide.

  8. Solar-Light-Driven Renewable Butanol Separation by Core-Shell Ag@ZIF-8 Nanowires.

    PubMed

    Liu, Xu; He, Liangcan; Zheng, Jianzhong; Guo, Jun; Bi, Feng; Ma, Xiang; Zhao, Kun; Liu, Yaling; Song, Rui; Tang, Zhiyong

    2015-06-01

    Core-shell Ag@ZIF-8 nanowires, where single Ag nanowires are coated with uniform zeolitic-imidazolate-framework-8 (ZIF-8) shells, successfully realize renewable adsorptive separation of low concentrations of butanol from an aqueous medium under solar light irradiation by taking advantage of the exceptional adsorption capability of the ZIF-8 shells toward butanol and the unique plasmonic photothermal effect of the Ag nanowire cores. Impressively, the high separation efficiency is maintained as almost unchanged, even after 10 adsorption/desorption cycles.

  9. Core/multishell nanowire heterostructures as multicolor, high-efficiency light-emitting diodes.

    PubMed

    Qian, Fang; Gradecak, Silvija; Li, Yat; Wen, Cheng-Yen; Lieber, Charles M

    2005-11-01

    We report the growth and characterization of core/multishell nanowire radial heterostructures, and their implementation as efficient and synthetically tunable multicolor nanophotonic sources. Core/multishell nanowires were prepared by metal-organic chemical vapor deposition with an n-GaN core and InxGa1-xN/GaN/p-AlGaN/p-GaN shells, where variation of indium mole fraction is used to tune emission wavelength. Cross-sectional transmission electron microscopy studies reveal that the core/multishell nanowires are dislocation-free single crystals with a triangular morphology. Energy-dispersive X-ray spectroscopy clearly shows shells with distinct chemical compositions, and quantitatively confirms that the thickness and composition of individual shells can be well controlled during synthesis. Electrical measurements show that the p-AlGaN/p-GaN shell structure yields reproducible hole conduction, and electroluminescence measurements demonstrate that in forward bias the core/multishell nanowires function as light-emitting diodes, with tunable emission from 365 to 600 nm and high quantum efficiencies. The ability to synthesize rationally III-nitride core/multishell nanowire heterostructures opens up significant potential for integrated nanoscale photonic systems, including multicolor lasers.

  10. Development of Yangbajing air shower core detector for a new EAS hybrid experiment

    NASA Astrophysics Data System (ADS)

    Liu, Jin-Sheng; Huang, Jing; Chen, Ding; Zhang, Ying; Zhai, Liu-Ming; Chen, Xu; Hu, Xiao-Bin; Lin, Yu-Hui; Zhang, Xue-Yao; Feng, Cun-Feng; Jia, Huan-Yu; Zhou, Xun-Xiu; Danzengluobu; Chen, Tian-Lu; Li, Hai-Jin; Liu, Mao-Yuan; Yuan, Ai-Fang

    2015-08-01

    Aiming at the observation of cosmic-ray chemical composition in the “knee” energy region, we have been developing a new type of air-shower core detector (YAC, Yangbajing Air shower Core detector array) to be set up at Yangbajing (90.522° E, 30.102° N, 4300 m above sea level, atmospheric depth: 606 g/m2) in Tibet, China. YAC works together with the Tibet air-shower array (Tibet-III) and an underground water Cherenkov muon detector array (MD) as a hybrid experiment. Each YAC detector unit consists of lead plates of 3.5 cm thickness and a scintillation counter which detects the burst size induced by high energy particles in the air-shower cores. The burst size can be measured from 1 MIP (Minimum Ionization Particle) to 106 MIPs. The first phase of this experiment, named “YAC- I”, consists of 16 YAC detectors each with a size of 40 cm×50 cm and distributed in a grid with an effective area of 10 m2. YAC- I is used to check hadronic interaction models. The second phase of the experiment, called “YAC- II”, consists of 124 YAC detectors with coverage of about 500 m2. The inner 100 detectors of 80 cm×50 cm each are deployed in a 10×10 matrix with a 1.9 m separation; the outer 24 detectors of 100 cm×50 cm each are distributed around these to reject non-core events whose shower cores are far from the YAC- II array. YAC- II is used to study the primary cosmic-ray composition, in particular, to obtain the energy spectra of protons, helium and iron nuclei between 5×1013 eV and 1016 eV, covering the “knee” and also connected with direct observations at energies around 100 TeV. We present the design and performance of YAC- II in this paper. Supported by grants from the National Natural Science Foundation of China (11078002, 11275212, 11165013), the Chinese Academy of Sciences (H9291450S3, Y4293211S5) and the Knowledge Innovation Fund of Institute of High Energy Physics (IHEP), China (H95451D0U2, H8515530U1)

  11. Shippingport operations with the Light Water Breeder Reactor core. (LWBR Development Program)

    SciTech Connect

    Budd, W.A.

    1986-03-01

    This report describes the operation of the Shippingport Atomic Power Station during the LWBR (Light Water Breeder Reactor) Core lifetime. It also summarizes the plant-oriented operations during the period preceding LWBR startup, which include the defueling of The Pressurized Water Reactor Core 2 (PWR-2) and the installation of the LWBR Core, and the operations associated with the defueling of LWBR. The intent of this report is to examine LWBR experience in retrospect and present pertinent and significant aspects of LWBR operations that relate primarily to the nuclear portion of the Station. The nonnuclear portion of the Station is discussed only as it relates to overall plant operation or to unusual problems which result from the use of conventional equipment in radioactive environments. 30 refs., 69 figs., 27 tabs.

  12. Computation of the Mutual Inductance between Air-Cored Coils of Wireless Power Transformer

    NASA Astrophysics Data System (ADS)

    Anele, A. O.; Hamam, Y.; Chassagne, L.; Linares, J.; Alayli, Y.; Djouani, K.

    2015-09-01

    Wireless power transfer system is a modern technology which allows the transfer of electric power between the air-cored coils of its transformer via high frequency magnetic fields. However, due to its coil separation distance and misalignment, maximum power transfer is not guaranteed. Based on a more efficient and general model available in the literature, rederived mathematical models for evaluating the mutual inductance between circular coils with and without lateral and angular misalignment are presented. Rather than presenting results numerically, the computed results are graphically implemented using MATLAB codes. The results are compared with the published ones and clarification regarding the errors made are presented. In conclusion, this study shows that power transfer efficiency of the system can be improved if a higher frequency alternating current is supplied to the primary coil, the reactive parts of the coils are compensated with capacitors and ferrite cores are added to the coils.

  13. 10 CFR 50.46 - Acceptance criteria for emergency core cooling systems for light-water nuclear power reactors.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... light-water nuclear power reactors. 50.46 Section 50.46 Energy NUCLEAR REGULATORY COMMISSION DOMESTIC... Approvals § 50.46 Acceptance criteria for emergency core cooling systems for light-water nuclear power reactors. (a)(1)(i) Each boiling or pressurized light-water nuclear power reactor fueled with uranium...

  14. 10 CFR 50.46 - Acceptance criteria for emergency core cooling systems for light-water nuclear power reactors.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... light-water nuclear power reactors. 50.46 Section 50.46 Energy NUCLEAR REGULATORY COMMISSION DOMESTIC... Approvals § 50.46 Acceptance criteria for emergency core cooling systems for light-water nuclear power reactors. (a)(1)(i) Each boiling or pressurized light-water nuclear power reactor fueled with uranium...

  15. 10 CFR 50.46 - Acceptance criteria for emergency core cooling systems for light-water nuclear power reactors.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... light-water nuclear power reactors. 50.46 Section 50.46 Energy NUCLEAR REGULATORY COMMISSION DOMESTIC... Approvals § 50.46 Acceptance criteria for emergency core cooling systems for light-water nuclear power reactors. (a)(1)(i) Each boiling or pressurized light-water nuclear power reactor fueled with uranium...

  16. 10 CFR 50.46 - Acceptance criteria for emergency core cooling systems for light-water nuclear power reactors.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... light-water nuclear power reactors. 50.46 Section 50.46 Energy NUCLEAR REGULATORY COMMISSION DOMESTIC... Approvals § 50.46 Acceptance criteria for emergency core cooling systems for light-water nuclear power reactors. (a)(1)(i) Each boiling or pressurized light-water nuclear power reactor fueled with uranium...

  17. 10 CFR 50.46 - Acceptance criteria for emergency core cooling systems for light-water nuclear power reactors.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... light-water nuclear power reactors. 50.46 Section 50.46 Energy NUCLEAR REGULATORY COMMISSION DOMESTIC... Approvals § 50.46 Acceptance criteria for emergency core cooling systems for light-water nuclear power reactors. (a)(1)(i) Each boiling or pressurized light-water nuclear power reactor fueled with uranium...

  18. The influence of inelastic neutrino interactions with light clusters on core-collapse supernova simulations

    NASA Astrophysics Data System (ADS)

    Furusawa, Shun; Nagakura, Hiroki; Sumiyoshi, Kohsuke; Yamada, Shoichi

    2014-12-01

    We perform numerical experiments to investigate the influence of inelastic neutrino reactions with light clusters in hot nuclear matter on core-collapse supernova simulations. These interactions have been neglected in most hydrodynamical supernova simulations. The neutrino absorptions and inelastic interactions with deuterons, tritons, helions and alpha particles are taken into account in the hydrodynamical simulations in addition to the ordinary charged- current interactions with nucleons. Axial symmetry is assumed but no equatorial symmetry is imposed. The time evolutions of shock waves are calculated with a simple light-bulb approximation for the neutrino transport and a multi-nuclei equation of state. We show that the heating rates of deuterons reach as high as ~ 10% of those of nucleons around the bottom of the gain region. On the other hand, alpha particles heat the matter near the shock wave, which is important when the shock wave expands and density and temperature of matter become low. It is also found that the models with heating by light clusters have different evolutions from those without it in non-linear evolution phase. The matter in the gain region has various densities and temperatures and there appear regions that are locally rich in deuterons and alpha particles. These results indicate that the inelastic reactions of light clusters, especially deuterons, should be incorporated in the simulations of core-collapse supernovae.

  19. Analysis of air quality and nighttime light for Indian urban regions

    NASA Astrophysics Data System (ADS)

    Misra, Prakhar; Takeuchi, Wataru

    2016-06-01

    Indian urban regions suffer severe air pollution issues. A 2014 study by WHO highlighted that out of 20 cities globally with worst air quality, 13 lie in India. Although insufficient ground monitoring data and incomplete air pollution source characterization impedes putting policy measures to tackle this issue, remote sensing and GIS can overcome this hurdle to some extent. To find out how much of this hazard is due to economic growth, past researches have tried to make use of socio-economic growth indicators like GDP, population or urban area to establish its correlation with air quality in urban centres. Since nightlight has been found to correlate well with economic conditions at national and city level, an attempt has been made to analyse it with air quality levels to find regions with high contribution of anthropogenic emissions. Nighttime light activity was observed through DayNight Band (DNB) of VIIRS sensor while the air quality levels were obtained for ANG and AOD (using MODIS sensor) and SO2 and NO2 (using OMI sensor). We have classified Indian landmass into 4 air-quality and DNB classes: LowLight- HighPollution, HighLight-HighPollution, LowLight-LowPollution and HighLight- LowPollution for each air quality species using June 2014 data. It was found that around half of urban regions show high AOD and ANG values. On the other hand almost all urban regions exhibit high SO2 and NO2 values.

  20. Light pollution from the ground, the air and the space

    NASA Astrophysics Data System (ADS)

    Sánchez de Miguel, A.; Zamorano, J.; Gómez Castaño, J.; Aubé, M.; Bará, S.; Gallego, J.; Kyba, C. C. M.; Lombraña, D.; Nievas, M.; Pascual, S.; Tapia, C.

    2015-05-01

    The sky brightness is one of the things that most harms astronomical observation, near cities and on mountain observatories. Currently there are several initiatives to control light pollution, but the sky brightness measurements are usually local. To exercise adequate control of light pollution is necessary measurements of light pollution sources and their relation to the spatiotemporal variation of the sky brightness. We use various approaches: data taken ashore with photometers SQM and relate emissions and detected with VIIRS and DMSP satellites. We also use multispectral data taken from the International Space Station to distinguish different types of lamps that contribute to light pollution. Finally we used a spectrograph SAND for temporal analysis of the evolution of the contribution of the lights in the sky brightness of a big city like Madrid. Also we have performed a citizen science program to classify the night time images taken from the ISS (Sánchez de Miguel et al. 2014, A&G, 55, 4, 36).

  1. Metal-silicate partitioning and the light element in the core (Invited)

    NASA Astrophysics Data System (ADS)

    Wood, B. J.; Wade, J.; Tuff, J.

    2009-12-01

    Most attempts to constrain the concentrations of “light” elements in the Earth’s core rely either on cosmochemical arguments or on arguments based on the densities and equations of state of Fe-alloys containing the element of concern. Despite its utility, the latter approach yields a wide range of permissible compositions and hence weak constraints. The major problem with the cosmochemical approach is that the abundances in the bulk Earth of all the candidate “light” elements- H, C, O, Si and S are highly uncertain because of their volatile behavior during planetary accretion. In contrast, refractory elements appear to be in approximately CI chondritic relative abundances in the Earth. This leads to the potential for using the partitioning of refractory siderophile elements between the mantle and core to constrain the concentrations of light elements in the core. Recent experimental metal-silicate partitioning data, coupled with mantle abundances of refractory siderophile elements (e.g. Wade and Wood, EPSL v.236, 78—95,2005; Kegler et. al. EPSL v.268, 28-40,2008) have shown that the core segregated from the mantle under high pressure conditions (~40 GPa). If a wide range of elements, from very siderophile, (e.g. Mo) through moderately (Ni, Co, W) to weakly siderophile (V, Cr, Nb, Si) are considered, the Earth also appears to have become more oxidized during accretion. Metal-silicate partitioning of some elements is also sensitive to the light element content of the metal. For example, Nb and W partitioning depend strongly on carbon, Mo on silicon and Cr on sulfur. Given the measured mantle abundances of the refractory elements, these observations enable the Si and C contents of the core to be constrained at ~5% and <2% respectively while partitioning is consistent with a cosmochemically-estimated S content of ~2%.

  2. Atmospheric light air ion concentrations and related meteorologic factors in Rezekne city, Latvia.

    PubMed

    Skromulis, Andris; Noviks, Gotfrids

    2012-04-01

    The well-minded impact of light negative air ions on human organism is still under discussion. The measurements of air ions are not widespread in Latvia yet. The paper presents new results of air pollution evaluation in Rezekne city. Measurements of positive and negative air ion concentrations in Rezekne city were taken during the spring, summer and autumn 2009 and during the winter 2010. Measurements were taken by portative air ions counter "Sapfir-3M" in eight different points of Rezekne city thrice a day. The concentrations of positive and negative air ions with mobility factor k > or = 0.4 cm2 V(-1) s(-1) were measured. Temperature, relative humidity, wind velocity, direction, etc., were also taken into account. The approximate interconnection between ionization and chemical and mechanical air pollution in relation with meteorological conditions was analyzed. The highest level of air ion concentration was observed in mornings, whereas in afternoons this concentration level decreased due to the growth of anthropogenic air pollution in the city, as light air ions, because of their charge, promoted the coagulation and the settlement of pollution particles. This regularity is typical for summer, whereas in spring, autumn and winter it is not characteristic. The unipolarity factor was usually less than 1 in mornings, but usually larger than 1 in afternoons especially in the most polluted city areas where minor concentration of air ions was detected. The ionization level is an original indicator of energetic saturation and aerosol pollution of atmospheric air.

  3. Ring waves as a mass transport mechanism in air-driven core-annular flows.

    PubMed

    Camassa, Roberto; Forest, M Gregory; Lee, Long; Ogrosky, H Reed; Olander, Jeffrey

    2012-12-01

    Air-driven core-annular fluid flows occur in many situations, from lung airways to engineering applications. Here we study, experimentally and theoretically, flows where a viscous liquid film lining the inside of a tube is forced upwards against gravity by turbulent airflow up the center of the tube. We present results on the thickness and mean speed of the film and properties of the interfacial waves that develop from an instability of the air-liquid interface. We derive a long-wave asymptotic model and compare properties of its solutions with those of the experiments. Traveling wave solutions of this long-wave model exhibit evidence of different mass transport regimes: Past a certain threshold, sufficiently large-amplitude waves begin to trap cores of fluid which propagate upward at wave speeds. This theoretical result is then confirmed by a second set of experiments that show evidence of ring waves of annular fluid propagating over the underlying creeping flow. By tuning the parameters of the experiments, the strength of this phenomenon can be adjusted in a way that is predicted qualitatively by the model.

  4. C2-C4 alkanes measured in a South Pole ice core: Are atmospheric histories of light hydrocarbons preserved in Antarctic ice?

    NASA Astrophysics Data System (ADS)

    Williams, M. B.; Aydin, M.; Saltzman, E. S.

    2007-12-01

    Non-methane hydrocarbons play a significant role in global atmospheric photochemical system, but we have little knowledge about their atmospheric variability on long time scales. In this study, we analyze ethane (C2H6), propane (C3H8) and n-butane (C4H10) in a South Pole ice core, to examine the potential for using polar ice cores to reconstruct atmospheric histories of these gases. Air was dry- extracted from 124 ice core samples from the SPRESSO core, a 295 m core drilled in 2002 near South Pole as part of the ITASE campaign. The mean gas ages estimated for these samples range from 150 B.C.E. to 1720 C.E. The average mixing ratios for ethane, propane, and n-butane are 798±417 ppt, 234±89 ppt and 117±48 ppt, respectively. Point to point variability generally lies within the estimate of analytical uncertainty. These measurements demonstrate that 1) recoverable amounts of light hydrocarbons exist in polar ice, and 2) there is no evidence of down-core trends to suggest systematic loss or production with time. However, the hydrocarbon levels in this ice core are considerably higher than those in modern air over Antarctica (by factors of 2, 7, and 10 respectively for ethane, propane, and n-butane). The ice core data are not normally distributed, but appear to have a lower limit with superimposed variability. These "baseline levels" are roughly 300 ppt (C2H6), 80 ppt (C3H8), and 40 ppt (C4H10) and are consistent with modern ambient air and firn air levels measured at South Pole. A working hypothesis to explain these results is that alkane levels in ice reflect a combination of two components: 1) entrapped air possibly recording the atmospheric histories of these gases, and 2) some source of alkane contamination that is generated at or near bubble close-off, but does not continue at depth. It is unlikely that the elevated alkane levels reflect contamination during storage, extraction, or analysis.

  5. Paleoarchean and Cambrian observations of the geodynamo in light of new estimates of core thermal conductivity

    NASA Astrophysics Data System (ADS)

    Tarduno, John; Bono, Richard; Cottrell, Rory

    2015-04-01

    Recent estimates of core thermal conductivity are larger than prior values by a factor of approximately three. These new estimates suggest that the inner core is a relatively young feature, perhaps as young as 500 million years old, and that the core-mantle heat flux required to drive the early dynamo was greater than previously assumed (Nimmo, 2015). Here, we focus on paleomagnetic studies of two key time intervals important for understanding core evolution in light of the revisions of core conductivity values. 1. Hadean to Paleoarchean (4.4-3.4 Ga). Single silicate crystal paleointensity analyses suggest a relatively strong magnetic field at 3.4-3.45 Ga (Tarduno et al., 2010). Paleointenity data from zircons of the Jack Hills (Western Australia) further suggest the presence of a geodynamo between 3.5 and 3.6 Ga (Tarduno and Cottrell, 2014). We will discuss our efforts to test for the absence/presence of the geodynamo in older Eoarchean and Hadean times. 2. Ediacaran to Early Cambrian (~635-530 Ma). Disparate directions seen in some paleomagnetic studies from this time interval have been interpreted as recording inertial interchange true polar wander (IITPW). Recent single silicate paleomagnetic analyses fail to find evidence for IITPW; instead a reversing field overprinted by secondary magnetizations is defined (Bono and Tarduno, 2015). Preliminary analyses suggest the field may have been unusually weak. We will discuss our on-going tests of the hypothesis that this interval represents the time of onset of inner core growth. References: Bono, R.K. & Tarduno, J.A., Geology, in press (2015); Nimmo, F., Treatise Geophys., in press (2015); Tarduno, J.A., et al., Science (2010); Tarduno, J.A. & Cottrell, R.D., AGU Fall Meeting (2014).

  6. Visible Light Responsive Catalyst for Air Water Purification Project

    NASA Technical Reports Server (NTRS)

    Wheeler, Raymond M.

    2014-01-01

    Investigate and develop viable approaches to render the normally UV-activated TIO2 catalyst visible light responsive (VLR) and achieve high and sustaining catalytic activity under the visible region of the solar spectrum.

  7. Lighting energy efficiency opportunities at Cheyenne Mountain Air Station

    SciTech Connect

    Molburg, J.C.; Rozo, A.J.; Sarles, J.K.; Haffenden, R.A.; Thimmapuram, P.R.; Cavallo, J.D.

    1996-06-01

    CMAS is an intensive user of electricity for lighting because of its size, lack of daylight, and 24-hour operating schedule. Argonne National Laboratory recently conducted a lighting energy conservation evaluation at CMAS. The evaluation included inspection and characterization of existing lighting systems, analysis of energy-efficient retrofit options, and investigation of the environmental effects that these lighting system retrofits could have when they are ready to be disposed of as waste. Argonne devised three retrofit options for the existing lighting systems at various buildings: (1) minimal retrofit--limited fixture replacement; (2) moderate retrofit--more extensive fixture replacement and limited application of motion detectors; and (3) advanced retrofit--fixture replacement, reduction in the number of lamps, expansion of task lighting, and more extensive application of motion detectors. Argonne used data on electricity consumption to analyze the economic and energy effects of these three retrofit options. It performed a cost analysis for each retrofit option in terms of payback. The analysis showed that lighting retrofits result in savings because they reduce electricity consumption, cooling load, and maintenance costs. The payback period for all retrofit options was found to be less than 2 years, with the payback period decreasing for more aggressive retrofits. These short payback periods derived largely from the intensive (24-hours-per-day) use of electric lighting at the facility. Maintenance savings accounted for more than half of the annual energy-related savings under the minimal and moderate retrofit options and slightly less than half of these savings under the advanced retrofit option. Even if maintenance savings were excluded, the payback periods would still be impressive: about 4.4 years for the minimal retrofit option and 2 years for the advanced option. The local and regional environmental impacts of the three retrofit options were minimal.

  8. Measurement of nitrophenols in rain and air by two-dimensional liquid chromatography-chemically active liquid core waveguide spectrometry.

    PubMed

    Ganranoo, Lucksagoon; Mishra, Santosh K; Azad, Abul K; Shigihara, Ado; Dasgupta, Purnendu K; Breitbach, Zachary S; Armstrong, Daniel W; Grudpan, Kate; Rappenglueck, Bernhard

    2010-07-01

    We report a novel system to analyze atmospheric nitrophenols (NPs). Rain or air sample extracts (1 mL) are preconcentrated on a narrow bore (2 mm) aliphatic anion exchanger. In the absence of strong retention of NPs exhibited by aromatic ion exchangers, retained NPs are eluted as a plug by injection of 100 microL of 0.1 M Na(2)SO(4) on to a short (2 x 50 mm) reverse phase C-18 column packed with 2.2 mum particles. The salt plug passes through the C-18 column unretained while the NPs are separated by an ammonium acetate buffered methanol-water eluent, compatible with mass spectrometry (MS). The eluted NPs are measured with a long path Teflon AF-based liquid core waveguide (0.15 x 1420 mm) illuminated by a 403 nm light emitting diode and detected by a monolithic photodiode-operational amplifier. The waveguide is rendered chemically active by suspending it over concentrated ammonia that permeates into the lumen. The NPs ionize to the yellow anion form (lambda(max) approximately 400 nm). The separation of 4-nitrophenol, 2,4-dinitrophenol, 2-methyl-4-nitrophenol, 3-methyl-4-nitrophenol, and 2-nitrophenol (these are the dominant NPs, typically in that order, in both rain and air of Houston and Arlington, TX, confirmed by tandem MS) takes just over 5 min with respective S/N = 3 limits of detection (LODs) of 60, 12, 30, 67, and 23 pg/mL compared to MS/MS LODs of 20, 49, 11, 20, and 210 pg/mL. Illustrative air and rain data are presented.

  9. Bolometric light curves and explosion parameters of 38 stripped-envelope core-collapse supernovae

    NASA Astrophysics Data System (ADS)

    Lyman, J. D.; Bersier, D.; James, P. A.; Mazzali, P. A.; Eldridge, J. J.; Fraser, M.; Pian, E.

    2016-03-01

    Literature data are collated for 38 stripped-envelope core-collapse supernovae (SE SNe; i.e. SNe IIb, Ib, Ic and Ic-BL) that have good light-curve coverage in more than one optical band. Using bolometric corrections derived in previous work, the bolometric light curve of each SN is recovered and template bolometric light curves provided. Peak light distributions and decay rates are investigated; SNe subtypes are not cleanly distinguished in this parameter space, although some grouping of types does occur and there is a suggestion of a Phillips-like relation for most SNe Ic-BL. The bolometric light curves are modelled with a simple analytical prescription and compared to results from more detailed modelling. Distributions of the explosion parameters show the extreme nature of SNe Ic-BL in terms of their 56Ni mass and the kinetic energy, however ejected masses are similar to other subtypes. SNe Ib and Ic have very similar distributions of explosion parameters, indicating a similarity in progenitors. SNe IIb are the most homogeneous subtype and have the lowest average values for 56Ni mass, ejected mass, and kinetic energy. Ejecta masses for each subtype and SE SNe as a whole are inconsistent with those expected from very massive stars. The majority of the ejecta mass distribution is well described by more moderately massive progenitors in binaries, indicating these are the dominant progenitor channel for SE SNe.

  10. Light Scattering by Ice Crystals Containing Air Bubbles

    NASA Astrophysics Data System (ADS)

    Zhang, J.; Panetta, R. L.; Yang, P.; Bi, L.

    2014-12-01

    The radiative effects of ice clouds are often difficult to estimate accurately, but are very important for interpretation of observations and for climate modeling. Our understanding of these effects is primarily based on scattering calculations, but due to the variability in ice habit it is computationally difficult to determine the required scattering and absorption properties, and the difficulties are only compounded by the need to include consideration of air and carbon inclusions of the sort frequently observed in collected samples. Much of the previous work on effects of inclusions in ice particles on scattering properties has been conducted with variants of geometric optics methods. We report on simulations of scattering by ice crystals with enclosed air bubbles using the pseudo-spectral time domain method (PSTD) and improved geometric optics method (IGOM). A Bouncing Ball Model (BBM) is proposed as a parametrization of air bubbles, and the results are compared with Monte Carlo radiative transfer calculations. Consistent with earlier studies, we find that air inclusions lead to a smoothing of variations in the phase function, weakening of halos, and a reduction of backscattering. We extend these studies by examining the effects of the particular arrangement of a fixed number of bubbles, as well as the effects of splitting a given number of bubbles into a greater number of smaller bubbles with the same total volume fraction. The result shows that the phase function will not change much for stochastic distributed air bubbles. It also shows that local maxima of phase functions are smoothed out for backward directions, when we break bubbles into small ones, single big bubble scatter favors more forward scattering than multi small internal scatters.

  11. Light clusters, pasta phases, and phase transitions in core-collapse supernova matter

    NASA Astrophysics Data System (ADS)

    Pais, Helena; Chiacchiera, Silvia; Providência, Constança

    2015-05-01

    The pasta phase in core-collapse supernova matter (finite temperatures and fixed proton fractions) is studied within relativistic mean-field models. Three different calculations are used for comparison: the Thomas-Fermi, the coexisting phases, and the compressible liquid drop approximations. The effects of including light clusters in nuclear matter and the densities at which the transitions between pasta configurations and to uniform matter occur are also investigated. The free energy, pressure, entropy, and chemical potentials in the range of particle number densities and temperatures expected to cover the pasta region are calculated. Finally, a comparison with a finite-temperature Skyrme-Hartree-Fock calculation is drawn.

  12. Physical properties of self-, dual-, and light-cured direct core materials.

    PubMed

    Rüttermann, Stefan; Alberts, Ian; Raab, Wolfgang H M; Janda, Ralf R

    2011-08-01

    The objective of this study is to evaluate flexural strength, flexural modulus, compressive strength, curing temperature, curing depth, volumetric shrinkage, water sorption, and hygroscopic expansion of two self-, three dual-, and three light-curing resin-based core materials. Flexural strength and water sorption were measured according to ISO 4049, flexural modulus, compressive strength, curing temperature, and curing depth according to well-proven, literature-known methods, and the volumetric behavior was determined by the Archimedes' principle. ANOVA was calculated to find differences between the materials' properties, and correlation of water sorption and hygroscopic expansion was analysed according to Pearson (p < 0.05). Clearfil Photo Core demonstrated the highest flexural strength (125 ± 12 MPa) and curing depth (15.2 ± 0.1 mm) and had the highest flexural modulus (≈12.6 ± 1.2 GPa) concertedly with Multicore HB. The best compressive strength was measured for Voco Rebilda SC and Clearfil DC Core Auto (≈260 ± 10 MPa). Encore SuperCure Contrast had the lowest water sorption (11.8 ± 3.3 µg mm(-3)) and hygroscopic expansion (0.0 ± 0.2 vol.%). Clearfil Photo Core and Encore SuperCure Contrast demonstrated the lowest shrinkage (≈2.1 ± 0.1 vol.%). Water sorption and hygroscopic expansion had a very strong positive correlation. The investigated core materials significantly differed in the tested properties. The performance of the materials depended on their formulation, as well as on the respective curing process. PMID:20372950

  13. (Gold core)@(ceria shell) nanostructures for plasmon-enhanced catalytic reactions under visible light.

    PubMed

    Li, Benxia; Gu, Ting; Ming, Tian; Wang, Junxin; Wang, Peng; Wang, Jianfang; Yu, Jimmy C

    2014-08-26

    Driving catalytic reactions with sunlight is an excellent example of sustainable chemistry. A prerequisite of solar-driven catalytic reactions is the development of photocatalysts with high solar-harvesting efficiencies and catalytic activities. Herein, we describe a general approach for uniformly coating ceria on monometallic and bimetallic nanocrystals through heterogeneous nucleation and growth. The method allows for control of the shape, size, and type of the metal core as well as the thickness of the ceria shell. The plasmon shifts of the Au@CeO2 nanostructures resulting from the switching between Ce(IV) and Ce(III) are observed. The selective oxidation of benzyl alcohol to benzaldehyde, one of the fundamental reactions for organic synthesis, performed under both broad-band and monochromatic light, demonstrates the visible-light-driven catalytic activity and reveals the synergistic effect on the enhanced catalysis of the Au@CeO2 nanostructures.

  14. High-angle light scattering to determine the optical fiber core

    NASA Astrophysics Data System (ADS)

    Świrniak, Grzegorz

    2015-06-01

    The aim of the paper is to discuss the possibility of non-invasive sizing of a step-index optical fiber with the use of a beam of light of low temporal coherence. For this purpose we examine the angular profile of light scattered from the fiber at a high angle. The scattered pattern comprises chiefly two coupled, twin rainbows and depends on the fiber physical characteristics, i.e. its dimensions, shape, and refractive index profile. In order to find a causal link between the scattering pattern and the fiber morphology, a spectral analysis (Fast Fourier Transform, FFT) is performed over the scattering intensity. From the spectral data, the core diameter of a step-index optical fiber is extracted inversely.

  15. AIRS First Light Data: Northern Europe, July 20, 2002

    NASA Technical Reports Server (NTRS)

    2002-01-01

    [figure removed for brevity, see original site] [figure removed for brevity, see original site] Figure 1Figure 2Figure 3

    These images, taken over northern Europe on July 20, 2002, depict a few of the different views of Earth and its atmosphere that are produced by the Atmospheric Infrared Sounder experiment system operating on NASA's Aqua spacecraft.

    The image in Figure 1 is from an infrared channel from the AIRS instrument that measures the surface temperature in clear areas and cloud top temperatures in cloudy areas. The image reveals very warm conditions in France and a storm off the east coast of the United Kingdom.

    The image in Figure 2 represents a microwave channel from the Advanced Microwave Sounding Unit instrument that sees through most clouds and observes surface conditions everywhere.

    The image in Figure 3 is a microwave channel from the Humidity Sounder for Brazil instrument that is very sensitive to humidity and does not see the surface at all, but instead reveals the structure of moisture streams in the troposphere.

    The infrared and microwave data from the AIRS experiment are integrated to retrieve a single set of temperature, moisture, and cloud values. These three channels represent only a small portion of the 2,400-channel multispectral experiment, whose primary objectives are to improve the accuracy of weather forecasts and to study climate change.

    The AIRS experiment system also takes pictures of the Earth at four visible and near-infrared wavelengths that can be combined into a color picture. This image shows a swirling low-pressure system over England, clear skies over much of France, and frontal systems in the North Atlantic. Because AIRS is sensitive to different wavelengths than your eye, the colors shown are different from what you would see. For example, plants appear very red to AIRS. There are also subtle color differences in the clouds that relate to their altitude and thickness (compare the white

  16. Inelastic Neutrino Reactions with Light Nuclei and Standing Accretion Shock Instability in Core-Collapse Supernovae

    NASA Astrophysics Data System (ADS)

    Furusawa, S.; Nagakura, H.; Sumiyoshi, K.; Yamada, S.

    2016-01-01

    We perform numerical experiments to investigate the influence of inelastic neutrino reactions with light nuclei on the standing accretion shock instability. The time evolutions of shock waves are calculated with a simple light-bulb approximation for the neutrino transport and a multi-nuclei equation of state. The neutrino absorptions and inelastic interactions with deuterons, tritons, helions and alpha particles are taken into account in the hydrodynamical simulations in addition to the ordinary charged-current interactions with nucleons. Axial symmetry is assumed but no equatorial symmetry is imposed. We show that the heating rates of deuterons reach as high as ∼ 10% of those of nucleons around the bottom of the gain region. On the other hands, alpha particles heat the matter near the shock wave, which is important when the shock wave expands and density and temperature of matter become low. It is also found that the models with heating by light nuclei have different evolutions from those without it in non-linear evolution phase. The matter in the gain region has various densities and temperatures and there appear regions that are locally rich in deuterons and alpha particles. These results indicate that the inelastic reactions of light nuclei, especially deuterons, should be incorporated in the simulations of core-collapse supernovae.

  17. Mode-based microparticle conveyor belt in air-filled hollow-core photonic crystal fiber.

    PubMed

    Schmidt, Oliver A; Euser, Tijmen G; Russell, Philip St J

    2013-12-01

    We show how microparticles can be moved over long distances and precisely positioned in a low-loss air-filled hollow-core photonic crystal fiber using a coherent superposition of two co-propagating spatial modes, balanced by a backward-propagating fundamental mode. This creates a series of trapping positions spaced by half the beat-length between the forward-propagating modes (typically a fraction of a millimeter). The system allows a trapped microparticle to be moved along the fiber by continuously tuning the relative phase between the two forward-propagating modes. This mode-based optical conveyor belt combines long-range transport of microparticles with a positional accuracy of 1 µm. The technique also has potential uses in waveguide-based optofluidic systems. PMID:24514492

  18. Off-resonance frequency operation for power transfer in a loosely coupled air core transformer

    DOEpatents

    Scudiere, Matthew B

    2012-11-13

    A power transmission system includes a loosely coupled air core transformer having a resonance frequency determined by a product of inductance and capacitance of a primary circuit including a primary coil. A secondary circuit is configured to have a substantially same product of inductance and capacitance. A back EMF generating device (e.g., a battery), which generates a back EMF with power transfer, is attached to the secondary circuit. Once the load power of the back EMF generating device exceeds a certain threshold level, which depends on the system parameters, the power transfer can be achieved at higher transfer efficiency if performed at an operating frequency less than the resonance frequency, which can be from 50% to 95% of the resonance frequency.

  19. Air fractionation in plate-like inclusions within the EPICA-DML deep ice core

    NASA Astrophysics Data System (ADS)

    Nedelcu, A.; Faria, S. H.; Kipfstuhl, S.; Schmidt, B.; Kuhs, W. F.

    2009-04-01

    On ice samples from the ice core recovered in the frame of the European Project for Ice Coring in Antarctica at the deep drilling site in Dronning Maud Land (75°00S; 00°04E) micro-Raman spectrochemical analysis was applied to typical relaxation features appearing after the extraction of an ice core. Essentially, these relaxation microinclusions are little planar polygonal cavities possessing hexagonal symmetry i.e. thin negative crystals lying on the basal plane of the hosting ice crystallite. Usually named plate-like inclusions, PLIs, they tend to change their aspect ratio becoming in general rounder, thicker or thinner depending on the equilibrium established between the structure-composition of the ice and the minute environmental temperature-pressure conditions around a specific PLI, but still preserving a very large aspect ratio (typically 20:1). Muguruma and others (1966) and Mae (1968) have reported studies on plate hexagonal voids, i.e. PLIs, produced (only) in tensile deformation tests of natural and artificial single ice crystals while the first report of PLIs in Antarctic ice cores was presented by Gow (1971). In spite of these early studies and the abundance of PLIs in stored ice core samples, extended investigations of these relaxation features are scarce. We present the results of the first successful study of the chemical composition of PLIs using microfocus Raman spectroscopy (Nedelcu and others, in press). We observe that the relaxation features contain mainly O2 and N2 in their interior, with N2/O2 ratios smaller than 3.7 (the nowadays atmospheric air N2/O2 ratio), indicating a general oxygen enrichment that is not so different from O2 enrichments reported in other investigations on polar ice samples (Nakahara and others, 1988, Ikeda and others, 1999). These results seem to lend support to the current hypothesis that O2 diffuses faster than N2 through the ice matrix (Ikeda-Fukazawa and others, 2001, 2005; Severinghaus and Battle, 2006). More

  20. Microstructured Air Cavities as High-Index Contrast Substrates with Strong Diffraction for Light-Emitting Diodes.

    PubMed

    Moon, Yoon-Jong; Moon, Daeyoung; Jang, Jeonghwan; Na, Jin-Young; Song, Jung-Hwan; Seo, Min-Kyo; Kim, Sunghee; Bae, Dukkyu; Park, Eun Hyun; Park, Yongjo; Kim, Sun-Kyung; Yoon, Euijoon

    2016-05-11

    Two-dimensional high-index-contrast dielectric gratings exhibit unconventional transmission and reflection due to their morphologies. For light-emitting devices, these characteristics help guided modes defeat total internal reflections, thereby enhancing the outcoupling efficiency into an ambient medium. However, the outcoupling ability is typically impeded by the limited index contrast given by pattern media. Here, we report strong-diffraction, high-index-contrast cavity engineered substrates (CESs) in which hexagonally arranged hemispherical air cavities are covered with a 80 nm thick crystallized alumina shell. Wavelength-resolved diffraction measurements and Fourier analysis on GaN-grown CESs reveal that the high-index-contrast air/alumina core/shell patterns lead to dramatic excitation of the low-order diffraction modes. Large-area (1075 × 750 μm(2)) blue-emitting InGaN/GaN light-emitting diodes (LEDs) fabricated on a 3 μm pitch CES exhibit ∼39% enhancement in the optical power compared to state-of-the-art, patterned-sapphire-substrate LEDs, while preserving all of the electrical metrics that are relevant to LED devices. Full-vectorial simulations quantitatively demonstrate the enhanced optical power of CES LEDs and show a progressive increase in the extraction efficiency as the air cavity volume is expanded. This trend in light extraction is observed for both lateral- and flip-chip-geometry LEDs. Measurements of far-field profiles indicate a substantial beaming effect for CES LEDs, despite their few-micron-pitch pattern. Near-to-far-field transformation simulations and polarization analysis demonstrate that the improved extraction efficiency of CES LEDs is ascribed to the increase in emissions via the top escape route and to the extraction of transverse-magnetic polarized light.

  1. Synthesis of fluorescent core-shell nanomaterials and strategies to generate white light

    SciTech Connect

    Singh, Amandeep; Kaur, Ramanjot; Pandey, O. P.; Wei, Xueyong; Sharma, Manoj E-mail: manojsharma@bilkent.edu.tr

    2015-07-28

    In this work, cadmium free core-shell ZnS:X/ZnS (X = Mn, Cu) nanoparticles have been synthesized and used for white light generation. First, the doping concentration of Manganese (Mn) was varied from 1% to 4% to optimize the dopant related emission and its optimal value was found to be 1%. Then, ZnS shell was grown over ZnS:Mn(1%) core to passivate the surface defects. Similarly, the optimal concentration of Copper (Cu) was found to be 0.8% in the range varied from 0.6% to 1.2%. In order to obtain an emission in the whole visible spectrum, dual doping of Mn and Cu was done in the core and the shell, respectively. A solid-solid mixing in different ratios of separately doped quantum dots (QDs) emitting in the blue green and the orange region was performed. Results show that the optimum mixture of QDs excited at 300 nm gives Commission Internationale del'Éclairage color coordinates of (0.35, 0.36), high color rendering index of 88, and correlated color temperature of 4704 K with minimum self-absorption.

  2. Effect of Zinc Incorporation on the Performance of Red Light Emitting InP Core Nanocrystals.

    PubMed

    Xi, Lifei; Cho, Deok-Yong; Besmehn, Astrid; Duchamp, Martial; Grützmacher, Detlev; Lam, Yeng Ming; Kardynał, Beata E

    2016-09-01

    This report presents a systematic study on the effect of zinc (Zn) carboxylate precursor on the structural and optical properties of red light emitting InP nanocrystals (NCs). NC cores were assessed using X-ray photoelectron spectroscopy (XPS), X-ray absorption spectroscopy (XAS), energy-dispersive X-ray spectroscopy (EDX), and high-resolution transmission electron microscopy (HRTEM). When moderate Zn:In ratios in the reaction pot were used, the incorporation of Zn in InP was insufficient to change the crystal structure or band gap of the NCs, but photoluminescence quantum yield (PLQY) increased dramatically compared with pure InP NCs. Zn was found to incorporate mostly in the phosphate layer on the NCs. PL, PLQY, and time-resolved PL (TRPL) show that Zn carboxylates added to the precursors during NC cores facilitate the synthesis of high-quality InP NCs by suppressing nonradiative and sub-band-gap recombination, and the effect is visible also after a ZnS shell is grown on the cores. PMID:27551948

  3. Core-shell conjugated microporous polymers: a new strategy for exploring color-tunable and -controllable light emissions.

    PubMed

    Xu, Yanhong; Nagai, Atsushi; Jiang, Donglin

    2013-02-25

    A core-shell strategy is demonstrated for designing a conjugated microporous polymer that allows the tuning of light emission over a wide wavelength range in a controlled manner. The polymers not only emit efficiently with an eight-fold enhanced luminescence but also sustain light emissions, irrespective of solvent and state.

  4. The impact of drought and air pollution on metal profiles in peat cores.

    PubMed

    Souter, Laura; Watmough, Shaun A

    2016-01-15

    Peat cores have long been used to reconstruct atmospheric metal deposition; however, debate remains regarding how well historical depositional patterns are preserved in peat. This study examined peat cores sampled from 14 peatlands in the Sudbury region of Ontario, Canada, which has a well-documented history of acid and metal deposition. Copper (Cu) and lead (Pb) concentrations within individual peat cores were strongly correlated and were elevated in the upper 10 cm, especially in the sites closest to the main Copper Cliff smelter. In contrast, nickel (Ni) and cobalt (Co) concentrations were often elevated at depths greater than 10 cm, indicating much greater post-depositional movement of these metals compared with Cu and Pb. Post-depositional movement of metals is supported by the observation that Ni and Co concentrations in peat pore water increased by approximately 530 and 960% for Ni and Co, respectively between spring and summer due to drought-induced acidification, but there was much less change in Cu concentration. Sphagnum cover and (210)Pb activity measured at 10 cm at the 14 sites significantly increased with distance from Copper Cliff, and the surface peat von Post score decreased with distance from Copper Cliff, indicating the rate of peat formation increases with distance from Sudbury presumably as a result of improved Sphagnum survival. This study shows that the ability of peat to preserve deposition histories of some metals is strongly affected by drought-induced post-depositional movement and that loss of Sphagnum due to air pollution impairs the rate of peat formation, further affecting metal profiles in peatlands. PMID:26473705

  5. The impact of drought and air pollution on metal profiles in peat cores.

    PubMed

    Souter, Laura; Watmough, Shaun A

    2016-01-15

    Peat cores have long been used to reconstruct atmospheric metal deposition; however, debate remains regarding how well historical depositional patterns are preserved in peat. This study examined peat cores sampled from 14 peatlands in the Sudbury region of Ontario, Canada, which has a well-documented history of acid and metal deposition. Copper (Cu) and lead (Pb) concentrations within individual peat cores were strongly correlated and were elevated in the upper 10 cm, especially in the sites closest to the main Copper Cliff smelter. In contrast, nickel (Ni) and cobalt (Co) concentrations were often elevated at depths greater than 10 cm, indicating much greater post-depositional movement of these metals compared with Cu and Pb. Post-depositional movement of metals is supported by the observation that Ni and Co concentrations in peat pore water increased by approximately 530 and 960% for Ni and Co, respectively between spring and summer due to drought-induced acidification, but there was much less change in Cu concentration. Sphagnum cover and (210)Pb activity measured at 10 cm at the 14 sites significantly increased with distance from Copper Cliff, and the surface peat von Post score decreased with distance from Copper Cliff, indicating the rate of peat formation increases with distance from Sudbury presumably as a result of improved Sphagnum survival. This study shows that the ability of peat to preserve deposition histories of some metals is strongly affected by drought-induced post-depositional movement and that loss of Sphagnum due to air pollution impairs the rate of peat formation, further affecting metal profiles in peatlands.

  6. Small field diode correction factors derived using an air core fibre optic scintillation dosimeter and EBT2 film

    NASA Astrophysics Data System (ADS)

    Ralston, Anna; Liu, Paul; Warrener, Kirbie; McKenzie, David; Suchowerska, Natalka

    2012-05-01

    There is no commercially available real-time dosimeter that can accurately measure output factors for field sizes down to 4 mm without the use of correction factors. Silicon diode detectors are commonly used but are not dosimetrically water equivalent, resulting in energy dependence and fluence perturbation. In contrast, plastic scintillators are nearly dosimetrically water equivalent. A fibre optic dosimeter (FOD) with a 0.8 mm3 plastic scintillator coupled to an air core light guide was used to measure the output factors for Novalis/BrainLab stereotactic cones of diameter 4-30 mm and Novalis MLC fields of width 5-100 mm. The FOD data matched the output factors measured by a 0.125 cm3 Semiflex ion chamber for the MLC fields above 30 mm and those measured with the EBT2 radiochromic film for the cones and MLC fields below 30 mm. Relative detector readings were obtained with four diode types (IBA SFD, EFD, PFD, PTW 60012) for the same fields. Empirical diode correction factors were determined by taking the ratio of FOD output factors to diode relative detector readings. The diodes were found to over-respond by 3%-16% for the smallest field. There was good agreement between different diodes of the same model number.

  7. Effects of a Circulating-water Garment and Forced-air Warming on Body Heat Content and Core Temperature

    PubMed Central

    Taguchi, Akiko; Ratnaraj, Jebadurai; Kabon, Barbara; Sharma, Neeru; Lenhardt, Rainer; Sessler, Daniel I.

    2005-01-01

    Background: Forced-air warming is sometimes unable to maintain perioperative normothermia. We therefore compared heat transfer, regional heat distribution, and core rewarming of forced-air warming with a novel circulating-water garment. Methods: Nine volunteers were each evaluated on two randomly ordered study days. They were anesthetized and cooled to a core temperature near 34°C. The volunteers were subsequently warmed for 2.5 hours with either a circulating-water garment or forced-air cover. Overall, heat balance was determined from the difference between cutaneous heat loss (thermal flux transducers) and metabolic heat production (oxygen consumption). Average arm and leg (peripheral) tissue temperatures were determined from 18 intramuscular needle thermocouples, 15 skin thermal flux transducers, and “deep” arm and foot thermometers. Results: Heat production (≈ 60 kcal/h) and loss (≈45 kcal/h) were similar with each treatment before warming. The increase in heat transfer across anterior portions of the skin surface was similar with each warming system (≈65 kcal/h). Forced-air warming had no effect on posterior heat transfer whereas circulating-water transferred 21 ± 9 kcal/h through the posterior skin surface after a half hour of warming. Over 2.5 h, circulating-water thus increased body heat content 56% more than forced air. Core temperatures thus increased faster than with circulating water than forced air, especially during the first hour, with the result that core temperature was 1.1 ± 0.7°C greater after 2.5 h (P < 0.001). Peripheral tissue heat content increased twice as much as core heat content with each device, but the core-to-peripheral tissue temperature gradient remained positive throughout the study. Conclusions: The circulating-water system transferred more heat than forced air, with the difference resulting largely from posterior heating. Circulating water rewarmed patients 0.4°C/h faster than forced air. A substantial peripheral-to-core

  8. Design and analysis of a nuclear reactor core for innovative small light water reactors

    NASA Astrophysics Data System (ADS)

    Soldatov, Alexey I.

    In order to address the energy needs of developing countries and remote communities, Oregon State University has proposed the Multi-Application Small Light Water Reactor (MASLWR) design. In order to achieve five years of operation without refueling, use of 8% enriched fuel is necessary. This dissertation is focused on core design issues related with increased fuel enrichment (8.0%) and specific MASLWR operational conditions (such as lower operational pressure and temperature, and increased leakage due to small core). Neutron physics calculations are performed with the commercial nuclear industry tools CASMO-4 and SIMULATE-3, developed by Studsvik Scandpower Inc. The first set of results are generated from infinite lattice level calculations with CASMO-4, and focus on evaluation of the principal differences between standard PWR fuel and MASLWR fuel. Chapter 4-1 covers aspects of fuel isotopic composition changes with burnup, evaluation of kinetic parameters and reactivity coefficients. Chapter 4-2 discusses gadolinium self-shielding and shadowing effects, and subsequent impacts on power generation peaking and Reactor Control System shadowing. The second aspect of the research is dedicated to core design issues, such as reflector design (chapter 4-3), burnable absorber distribution and programmed fuel burnup and fuel use strategy (chapter 4-4). This section also includes discussion of the parameters important for safety and evaluation of Reactor Control System options for the proposed core design. An evaluation of the sensitivity of the proposed design to uncertainty in calculated parameters is presented in chapter 4-5. The results presented in this dissertation cover a new area of reactor design and operational parameters, and may be applicable to other small and large pressurized water reactor designs.

  9. Light Transmission Fluctuations from Extended Air Showers Produced by Cosmic-Rays and Gamma-Rays

    NASA Astrophysics Data System (ADS)

    Taylor, Stuart

    Cosmic-ray and gamma-ray experiments that use the atmosphere as a calorimeter, such as the High Resolution Fly's Eye (HiRes) and the Telescope Array (TA), require understanding the transmission of the light from the air shower of particles produced by the cosmic-ray or gamma-ray striking the atmosphere. To better understand the scattering and transmission of light to the detectors, HiRes measures light from different calibrated sources. We compare scattered light from laser shots a few kilometers away from the two HiRes detectors with direct light from stable portable light sources placed a few meters in front of the phototubes. We use two HiRes detectors to study and isolate contributions to fluctuations of the measured light. These contributions include fluctuations in the source intensity, the night sky background, scattering and transmission of the laser beam, the phototubes and electronics, and photostatistics. N o rth Mirror Fields of View

  10. Interaction of Light Filaments Generated by Femtosecond Laser Pulses in Air

    SciTech Connect

    Xi Tingting; Lu Xin; Zhang Jie

    2006-01-20

    The interaction of two light filaments propagating in air is simulated. Simulations show that the interaction of the two light filaments displays interesting features such as attraction, fusion, repulsion, and spiral propagation, depending on the relative phase shift and the crossing angle between them. A long and stable channel can be formed by fusing two in-phase light filaments. The channel becomes unstable with the increase of the crossing angle and phase shift. The interaction of two light filaments in different planes is studied and the spiral propagation is observed.

  11. Effects of lights of different color temperature on the nocturnal changes in core temperature and melatonin in humans.

    PubMed

    Morita, T; Tokura, H

    1996-09-01

    A variety of types of artificial illumination has recently become available, differing in the quality of illumination and range of color temperature. In our previous studies we found that in subjects with normal color vision the nocturnal fall in core temperature and the increase of urinary melatonin excretion were suppressed by bright blue or green light, but not by bright red or dim lights. The aim of our present study was to examine from the view point of chronobiology whether the lights of different color temperature often used in everyday life may affect core temperature and urinary melatonin secretion differently. Experiments were carried out on five subjects with normal color vision. They were exposed for 5 hr (from 21:00 h to 2:00 h) to two kinds of bright (1000 lx) light of different color temperature (6500 K, 3000 K) with dim (50 lx) light as a control; after exposure they slept in darkness. Our main results were as follows: The light with a high color temperature of 6500 K more strongly suppressed the nocturnal fall of the core temperature and the nocturnal increase of melatonin secretion than the light with a low color temperature of 3000 K. This difference was particularly evident for core temperature during the sleep period following experimental illumination.

  12. Light extinction by aerosols during summer air pollution

    NASA Technical Reports Server (NTRS)

    Kaufman, Y. J.; Fraser, R. S.

    1983-01-01

    In order to utilize satellite measurements of optical thickness over land for estimating aerosol properties during air pollution episodes, the optical thickness was measured from the surface and investigated. Aerosol optical thicknesses have been derived from solar transmission measurements in eight spectral bands within the band lambda 440-870 nm during the summers of 1980 and 1981 near Washington, DC. The optical thicknesses for the eight bands are strongly correlated. It was found that first eigenvalue of the covariance matrix of all observations accounts for 99 percent of the trace of the matrix. Since the measured aerosol optical thickness was closely proportional to the wavelength raised to a power, the aerosol size distribution derived from it is proportional to the diameter (d) raised to a power for the range of diameters between 0.1 to 1.0 micron. This power is insensitive to the total optical thickness. Changes in the aerosol optical thickness depend on several aerosol parameters, but it is difficult to identify the dominant one. The effects of relative humidity and accumulation mode concentration on the optical thickness are analyzed theoretically, and compared with the measurements.

  13. Transmission of Curing Light through Moist, Air-Dried, and EDTA Treated Dentine and Enamel

    PubMed Central

    Uusitalo, E.; Varrela, J.; Lassila, L.; Vallittu, P. K.

    2016-01-01

    Objective. This study measured light transmission through enamel and dentin and the effect of exposed dentinal tubules to light propagation. Methods. Light attenuation through enamel and dentin layers of various thicknesses (1 mm, 2 mm, 3 mm, and 4 mm) was measured using specimens that were (1) moist and (2) air-dried (n = 5). Measurements were repeated after the specimens were treated with EDTA. Specimens were transilluminated with a light curing unit (maximum power output 1869 mW/cm2), and the mean irradiance power of transmitting light was measured. The transmission of light through teeth was studied using 10 extracted intact human incisors and premolars. Results. Transmitted light irradiance through 1 mm thick moist discs was 500 mW/cm2 for enamel and 398 mW/cm2 for dentin (p < 0.05). The increase of the specimen thickness decreased light transmission in all groups (p < 0.005), and moist specimens attenuated light less than air-dried specimens in all thicknesses (p < 0.05). EDTA treatment increased light transmission from 398 mW/cm2 to 439 mW/cm2 (1 mm dentin specimen thickness) (p < 0.05). Light transmission through intact premolar was 6.2 mW/cm2 (average thickness 8.2 mm) and through incisor was 37.6 mW/cm2 (average thickness 5.6 mm). Conclusion. Light transmission through enamel is greater than that through dentin, probably reflecting differences in refractive indices and extinction coefficients. Light transmission through enamel, dentin, and extracted teeth seemed to follow Beer-Lambert's law. PMID:27446954

  14. Light-Harvesting Nanoparticle Core-Shell Clusters with Controllable Optical Output.

    PubMed

    Sun, Dazhi; Tian, Ye; Zhang, Yugang; Xu, Zhihua; Sfeir, Matthew Y; Cotlet, Mircea; Gang, Oleg

    2015-06-23

    We used DNA self-assembly methods to fabricate a series of core-shell gold nanoparticle-DNA-colloidal quantum dot (AuNP-DNA-Qdot) nanoclusters with satellite-like architecture to modulate optical (photoluminescence) response. By varying the intercomponent distance through the DNA linker length designs, we demonstrate precise tuning of the plasmon-exciton interaction and the optical behavior of the nanoclusters from regimes characterized by photoluminescence quenching to photoluminescence enhancement. The combination of detailed X-ray scattering probing with photoluminescence intensity and lifetime studies revealed the relation between the cluster structure and its optical output. Compared to conventional light-harvesting systems like conjugated polymers and multichromophoric dendrimers, the proposed nanoclusters bring enhanced flexibility in controlling the optical behavior toward a desired application, and they can be regarded as controllable optical switches via the optically pumped color.

  15. Core design study of a supercritical light water reactor with double row fuel rods

    SciTech Connect

    Zhao, C.; Wu, H.; Cao, L.; Zheng, Y.; Yang, J.; Zhang, Y.

    2012-07-01

    An equilibrium core for supercritical light water reactor has been designed. A novel type of fuel assembly with dual rows of fuel rods between water rods is chosen and optimized to get more uniform assembly power distributions. Stainless steel is used for fuel rod cladding and structural material. Honeycomb structure filled with thermal isolation is introduced to reduce the usage of stainless steel and to keep moderator temperature below the pseudo critical temperature. Water flow scheme with ascending coolant flow in inner regions is carried out to achieve high outlet temperature. In order to enhance coolant outlet temperature, the radial power distributions needs to be as flat as possible through operation cycle. Fuel loading pattern and control rod pattern are optimized to flatten power distribution at inner regions. Axial fuel enrichment is divided into three parts to control axial power peak, which affects maximum cladding surface temperature. (authors)

  16. Optimization of 1D ZnO@TiO2 core-shell nanostructures for enhanced photoelectrochemical water splitting under solar light illumination.

    PubMed

    Hernández, Simelys; Cauda, Valentina; Chiodoni, Angelica; Dallorto, Stefano; Sacco, Adriano; Hidalgo, Diana; Celasco, Edvige; Pirri, Candido Fabrizio

    2014-08-13

    A fast and low-cost sol-gel synthesis used to deposit a shell of TiO2 anatase onto an array of vertically aligned ZnO nanowires (NWs) is reported in this paper. The influence of the annealing atmosphere (air or N2) and of the NWs preannealing process, before TiO2 deposition, on both the physicochemical characteristics and photoelectrochemical (PEC) performance of the resulting heterostructure, was studied. The efficient application of the ZnO@TiO2 core-shells for the PEC water-splitting reaction, under simulated solar light illumination (AM 1.5G) solar light illumination in basic media, is here reported for the first time. This application has had a dual function: to enhance the photoactivity of pristine ZnO NWs and to increase the photodegradation stability, because of the protective role of the TiO2 shell. It was found that an air treatment induces a better charge separation and a lower carrier recombination, which in turn are responsible for an improvement in the PEC performance with respect to N2-treated core-shell materials. Finally, a photocurrent of 0.40 mA/cm(2) at 1.23 V versus RHE (2.2 times with respect to the pristine ZnO NWs) was obtained. This achievement can be regarded as a valuable result, considering similar nanostructured electrodes reported in the literature for this application.

  17. Measuring air core characteristics of a pressure-swirl atomizer via a transparent acrylic nozzle at various Reynolds numbers

    SciTech Connect

    Lee, Eun J.; Oh, Sang Youp; Kim, Ho Y.; Yoon, Sam S.; James, Scott C.

    2010-11-15

    Because of thermal fluid-property dependence, atomization stability (or flow regime) can change even at fixed operating conditions when subject to temperature change. Particularly at low temperatures, fuel's high viscosity can prevent a pressure-swirl (or simplex) atomizer from sustaining a centrifugal-driven air core within the fuel injector. During disruption of the air core inside an injector, spray characteristics outside the nozzle reflect a highly unstable, nonlinear mode where air core length, Sauter mean diameter (SMD), cone angle, and discharge coefficient variability. To better understand injector performance, these characteristics of the pressure-swirl atomizer were experimentally investigated and data were correlated to Reynolds numbers (Re). Using a transparent acrylic nozzle, the air core length, SMD, cone angle, and discharge coefficient are observed as a function of Re. The critical Reynolds numbers that distinguish the transition from unstable mode to transitional mode and eventually to a stable mode are reported. The working fluids are diesel and a kerosene-based fuel, referred to as bunker-A. (author)

  18. The Learning-Focused Transformation of Biology and Physics Core Courses at the U.S. Air Force Academy

    ERIC Educational Resources Information Center

    Sagendorf, Kenneth; Noyd, Robert K.; Morris, D. Brent

    2009-01-01

    An institution-wide focus on deep learning has made significant changes in the biology and physics core course curriculum at the U.S. Air Force Academy. The biology course director has reworked course objectives to reflect the learning-focused approach to teaching, while the physics curriculum has adopted new learning outcomes and ways to…

  19. Coherent light transmission properties of commercial photonic crystal hollow core optical fiber.

    PubMed

    Cranch, G A; Miller, G A

    2015-11-01

    Photonic crystal hollow core fiber (PC-HCF) has enabled many exciting new applications in nonlinear optics and spectroscopy. However, to date there has been less impact in coherent applications where preservation of optical phase over long fiber lengths is crucial. This paper presents characteristics of three commercially available PC-HCFs relevant to coherent applications including higher-order mode analysis, birefringence and polarization-dependent loss, and their impact on coherent light transmission in PC-HCF. Multipath interference due to higher-order mode propagation and Fresnel reflection is shown to generate excess intensity noise in transmission, which can be suppressed by up to 20 dB through high frequency phase modulation of the source laser. To demonstrate the potential of PC-HCF in high performance sensing, a Mach-Zehnder interferometer (MZI) incorporating 10 m of PC-HCF in each arm is characterized and demonstrates a phase resolution (59×10(-9)  rad/Hz(1/2) at 30 kHz) close to the shot noise limit, which is better than can be achieved in a MZI made with the same length of single mode solid core fiber because of the limit set by fundamental thermodynamic noise (74×10(-9)  rad/Hz(1/2) at 30 kHz).

  20. Coherent light transmission properties of commercial photonic crystal hollow core optical fiber.

    PubMed

    Cranch, G A; Miller, G A

    2015-11-01

    Photonic crystal hollow core fiber (PC-HCF) has enabled many exciting new applications in nonlinear optics and spectroscopy. However, to date there has been less impact in coherent applications where preservation of optical phase over long fiber lengths is crucial. This paper presents characteristics of three commercially available PC-HCFs relevant to coherent applications including higher-order mode analysis, birefringence and polarization-dependent loss, and their impact on coherent light transmission in PC-HCF. Multipath interference due to higher-order mode propagation and Fresnel reflection is shown to generate excess intensity noise in transmission, which can be suppressed by up to 20 dB through high frequency phase modulation of the source laser. To demonstrate the potential of PC-HCF in high performance sensing, a Mach-Zehnder interferometer (MZI) incorporating 10 m of PC-HCF in each arm is characterized and demonstrates a phase resolution (59×10(-9)  rad/Hz(1/2) at 30 kHz) close to the shot noise limit, which is better than can be achieved in a MZI made with the same length of single mode solid core fiber because of the limit set by fundamental thermodynamic noise (74×10(-9)  rad/Hz(1/2) at 30 kHz). PMID:26560626

  1. Stationary rotary force waves on the liquid-air core interface of a swirl atomizer

    NASA Astrophysics Data System (ADS)

    Chinn, J. J.; Cooper, D.; Yule, A. J.; Nasr, G. G.

    2016-10-01

    A one-dimensional wave equation, applicable to the waves on the surface of the air-core of a swirl atomizer is derived analytically, by analogy to the similar one-dimensional wave equation derivation for shallow-water gravity waves. In addition an analogy to the flow of water over a weir is used to produce an analytical derivation of the flow over the lip of the outlet of a swirl atomizer using the principle of maximum flow. The principle of maximum flow is substantiated by reference to continuity of the discharge in the direction of streaming. For shallow-water gravity waves, the phase velocity is the same expression as for the critical velocity over the weir. Similarly, in the present work, the wave phase velocity on the surface of the air-core is shown to be the same expression as for the critical velocity for the flow at the outlet. In addition, this wave phase velocity is shown to be the square root of the product of the radial acceleration and the liquid thickness, as analogous with the wave phase velocity for shallow water gravity waves, which is the square root of the product of the acceleration due to gravity and the water depth. The work revisits the weirs and flumes work of Binnie et al. but using a different methodology. The results corroborate with the work of Binnie. High speed video, Laser Doppler Anemometry and deflected laser beam experimental work has been carried out on an oversize Perspex (Plexiglas) swirl atomizer. Three distinctive types of waves were detected: helical striations, low amplitude random ripples and low frequency stationary waves. It is the latter wave type that is considered further in this article. The experimentally observed waves appear to be stationary upon the axially moving flow. The mathematical analysis allows for the possibility of a negative value for the phase velocity expression. Therefore the critical velocity and the wave phase velocity do indeed lead to stationary waves in the atomizer. A quantitative comparison

  2. Static and dynamic evanescent wave light scattering studies of diblock copolymers adsorbed at the air/water interface

    NASA Astrophysics Data System (ADS)

    Lin, Binhua; Rice, Stuart A.; Weitz, D. A.

    1993-11-01

    We report the results of static and dynamic evanescent wave light scattering studies of a monolayer of a diblock copolymer, polystyrene-b-polymethylmethacrylate (PS-b-PMMA) with weight averaged molecular weights (Mw) of 880 000:290 000 supported at the air/water interface. Our studies probe the interfacial structural and dynamic properties of the monolayer on a length scale which is a fraction of the wavelength of light. The static light scattering studies were carried out as a function of polymer surface coverage and temperature; we also report some preliminary data for the dependence of the static structure function on the relative molecular weights of the PS and PMMA blocks. The complementary dynamic light scattering studies were carried out only as a function of surface coverage. Our data suggest that, upon spreading in the air/water interface, PS-b-PMMA (880:290 K) copolymers form thin disklike aggregates containing about 240 molecules. These data are consistent with a model in which each such aggregate is a ``furry disk'' with a dense core consisting of a layer of collapsed PS blocks atop a thin layer of extended PMMA blocks on the water surface and a brushlike boundary of extended PMMA blocks. The data show that the furry disks diffuse freely when the surface coverage is small, but when the surface coverage is large, they are immobile. Our data also suggest that the furry disks can aggregate to form even larger ``islands'' of disks with an extension greater than 20 μm. The static structure function of the assembly of furry disks is well described, over a wide range of surface coverage, by the structure factor of a two-dimensional hard disk fluid modulated by a two-dimensional hard disk form factor.

  3. Optical properties of plasmonic light-emitting diodes based on flip-chip III-nitride core-shell nanowires.

    PubMed

    Nami, Mohsen; Feezell, Daniel F

    2014-12-01

    In this work, we utilize the finite difference time domain (FDTD) method to investigate the Purcell factor, light extraction efficiency (EXE), and cavity quality parameter (Q), and to predict the modulation response of Ag-clad flip-chip GaN/InGaN core-shell nanowire light-emitting diodes (LEDs) with the potential for electrical injection. We consider the need for a pn-junction, the effects of the substrate, and the limitations of nanoscale fabrication techniques in the evaluation. The investigated core-shell nanowire consists of an n-GaN core, surrounded by nonpolar m-plane quantum wells, p-GaN, and silver cladding layers. The core-shell nanowire geometry exhibits a Purcell factor of 57, resulting in a predicted limit of 30 GHz for the 3dB modulation bandwidth.

  4. Air-core microcavities and metal-dielectric filters - building blocks for optofluidic microsystems

    NASA Astrophysics Data System (ADS)

    Allen, Trevor Warren

    reflection-less tunneling through a dielectric-metal-dielectric unit cell. For normal-incidence light in air, only a specific and impractically large dielectric index can enable a perfect admittance match. For off-normal incidence of TE-polarized light, an admittance match is obtained for a specific angle determined by the index of the ambient and dielectric media and the thickness and index of the metal. For TM-polarized light, admittance matching is possible for surface-plasmon-mediated tunneling. These results provide important insight for the design and optimization of optical filters and superlenses.

  5. Analysis of an Aircraft Honeycomb Sandwich Panel with Circular Face Sheet/Core Disbond Subjected to Ground-Air Pressurization

    NASA Technical Reports Server (NTRS)

    Rinker, Martin; Krueger, Ronald; Ratcliffe, James

    2013-01-01

    The ground-air pressurization of lightweight honeycomb sandwich structures caused by alternating pressure differences between the enclosed air within the honeycomb core and the ambient environment is a well-known and controllable loading condition of aerospace structures. However, initial face sheet/core disbonds intensify the face sheet peeling effect of the internal pressure load significantly and can decrease the reliability of the sandwich structure drastically. Within this paper, a numerical parameter study was carried out to investigate the criticality of initial disbonds in honeycomb sandwich structures under ground-air pressurization. A fracture mechanics approach was used to evaluate the loading at the disbond front. In this case, the strain energy release rate was computed via the Virtual Crack Closure Technique. Special attention was paid to the pressure-deformation coupling which can decrease the pressure load within the disbonded sandwich section significantly when the structure is highly deformed.

  6. Lateral distribution of high energy hadrons and gamma ray in air shower cores observed with emulsion chambers

    NASA Technical Reports Server (NTRS)

    Matano, T.; Machida, M.; Kawasumi, N.; Tsushima, I.; Honda, K.; Hashimoto, K.; Navia, C. E.; Matinic, N.; Aquirre, C.

    1985-01-01

    A high energy event of a bundle of electrons, gamma rays and hadronic gamma rays in an air shower core were observed. The bundles were detected with an emulsion chamber with thickness of 15 cm lead. This air shower is estimated to be initiated with a proton with energy around 10 to the 17th power to 10 to the 18th power eV at an altitude of around 100 gmc/2. Lateral distributions of the electromagnetic component with energy above 2 TeV and also the hadronic component of energy above 6 TeV of this air shower core were determined. Particles in the bundle are produced with process of the development of the nuclear cascade, the primary energy of each interaction in the cascade which produces these particles is unknown. To know the primary energy dependence of transverse momentum, the average products of energy and distance for various average energies of secondary particles are studied.

  7. Using strobe lights, air bubble curtains for cost-effective fish diversion

    SciTech Connect

    McCauley, D.J.; Navarro, J.E.; Mountouri, L.

    1996-04-01

    Faced with a high, and potentially costly, rate of fish turbine passage, a northern Michigan hydro project owner began investigating the use of behavioral barriers to divert fish away from turbines. Strobe lights, with and without air bubbles, proved to be highly effective, yielding dramatic reductions in the number of fish entrained.

  8. Measurement of air and nitrogen fluorescence light yields induced by electron beam for UHECR experiments

    NASA Astrophysics Data System (ADS)

    Colin, P.; Chukanov, A.; Grebenyuk, V.; Naumov, D.; Nédélec, P.; Nefedov, Y.; Onofre, A.; Porokhovoi, S.; Sabirov, B.; Tkatchev, L.; Macfly Collaboration

    2007-06-01

    Most of the Ultra High Energy Cosmic Ray (UHECR) experiments and projects (HiRes, AUGER, TA, EUSO, TUS, etc.) use air fluorescence to detect and measure extensive air showers (EAS). The precise knowledge of the Fluorescence Light Yield (FLY) is of paramount importance for the reconstruction of UHECR. The MACFLY—Measurement of Air Cherenkov and Fluorescence Light Yield—experiment has been designed to perform such FLY measurements. In this paper we will present the results of FLY in the 290-440 nm wavelength range for dry air and pure nitrogen, both excited by electrons with energy of 1.5 MeV, 20 GeV and 50 GeV. The experiment uses a 90Sr radioactive source for low energy measurement and a CERN SPS e - beam for high energy. We find that the FLY is proportional to the deposited energy ( Ed) in the gas and we show that the air fluorescence properties remain constant independently of the electron energy. At the reference point: atmospheric dry air at 1013 hPa and 23 °C, the ratio FLY/ Ed = 17.6 photon/MeV with a systematic error of 13.2%.

  9. Air and silica core Bragg fibers for radiation delivery in the wavelength range 0.6-1.5 μ m

    NASA Astrophysics Data System (ADS)

    Frank, Milan; Jelínek, Michal; Kubeček, Václav; Kašík, Ivan; Podrazký, Ondřej; Matějec, Vlastimil

    2016-09-01

    This paper presents fundamental characteristics of laboratory designed and fabricated Bragg fibers with air and silica cores at wavelengths of 632, 975, 1064 and 1550 nm. Fibers with the 26- μ m-silica core and 5- or 73- μ m-air cores in diameters and claddings of 3 pairs of Bragg layers were prepared from one preform. The overall transmittance, attenuation coefficients, coupling losses, bending losses, and damage-intensity thresholds were determined using four continuous-wave laser sources with the maximum output power of 300 mW and a pulsed 9 ns laser with the maximum output energy up to 1 mJ. The lowest attenuation coefficient of about 70 dB/km was determined at 1064 nm with the 73- μ m-air-core Bragg fiber. All fibers have been found to exhibit negligible bending losses down to the bending diameters of 5 cm. In comparison with the conventional gradient optical fiber, all the prepared Bragg fibers have approximately six times higher damage intensity threshold of about 30 GWcm-2 and therefore they are very suitable for high power laser radiation delivery.

  10. Importance of air bubbles in the core of coated pellets: Synchrotron X-ray microtomography allows for new insights.

    PubMed

    Fahier, J; Muschert, S; Fayard, B; Velghe, C; Byrne, G; Doucet, J; Siepmann, F; Siepmann, J

    2016-09-10

    High-resolution X-ray microtomography was used to get deeper insight into the underlying mass transport mechanisms controlling drug release from coated pellets. Sugar starter cores were layered with propranolol HCl and subsequently coated with Kollicoat SR, plasticized with 10% TEC. Importantly, synchrotron X-ray computed microtomography (SR-μCT) allowed direct, non-invasive monitoring of crack formation in the film coatings upon exposure to the release medium. Propranolol HCl, as well as very small sugar particles from the pellets' core, were expulsed through these cracks into the surrounding bulk fluid. Interestingly, SR-μCT also revealed the existence of numerous tiny, air-filled pores (varying in size and shape) in the pellet cores before exposure to the release medium. Upon water penetration into the system, the contents of the pellet cores became semi-solid/liquid. Consequently, the air-pockets became mobile and fused together. They steadily increased in size (and decreased in number). Importantly, "big" air bubbles were often located in close vicinity of a crack within the film coating. Thus, they play a potentially crucial role for the control of drug release from coated pellets. PMID:27374626

  11. Towards constraining the stratosphere-troposphere exchange of radiocarbon: strategies of stratospheric 14CO2 measurements using AirCore

    NASA Astrophysics Data System (ADS)

    Chen, Huilin; Paul, Dipayan; Meijer, Harro; Miller, John; Kivi, Rigel; Krol, Maarten

    2016-04-01

    Radiocarbon (14C) plays an important role in the carbon cycle studies to understand both natural and anthropogenic carbon fluxes, but also in atmospheric chemistry to constrain hydroxyl radical (OH) concentrations in the atmosphere. Apart from the enormous 14C emissions from nuclear bomb testing in the 1950s and 1960s, radiocarbon is primarily produced in the stratosphere due to the cosmogenic production. To this end, better understanding the stratospheric radiocarbon source is very useful to advance the use of radiocarbon for these applications. However, stratospheric 14C observations have been very limited so that there are large uncertainties on the magnitude and the location of the 14C production as well as the transport of radiocarbon from the stratosphere to the troposphere. Recently we have successfully made stratospheric 14C measurements using AirCore samples from Sodankylä, Northern Finland. AirCore is an innovative atmospheric sampling system, which passively collects atmospheric air samples into a long piece of coiled stainless steel tubing during the descent of a balloon flight. Due to the relatively low cost of the consumables, there is a potential to make such AirCore profiling in other parts of the world on a regular basis. In this study, we simulate the 14C in the atmosphere and assess the stratosphere-troposphere exchange of radiocarbon using the TM5 model. The Sodankylä radiocarbon measurements will be used to verify the performance of the model at high latitude. Besides this, we will also evaluate the influence of different cosmogenic 14C production scenarios and the uncertainties in the OH field on the seasonal cycles of radiocarbon and on the stratosphere-troposphere exchange, and based on the results design a strategy to set up a 14C measurement program using AirCore.

  12. Measurement of air-fluorescence-light yield induced by an electromagnetic shower

    NASA Astrophysics Data System (ADS)

    MACFLY Collaboration; Colin, P.; Chukanov, A.; Grebenyuk, V.; Naumov, D.; Nédélec, P.; Nefedov, Yu.; Onofre, A.; Porokhovoi, S.; Sabirov, B.; Tkatchev, L.

    2009-01-01

    For most of the ultra-high-energy cosmic ray (UHECR) experiments and projects (HiRes, AUGER, TA, JEM-EUSO, TUS, …), the detection technique of extensive air showers is based, at least, on the measurement of the air-fluorescence-induced signal. The knowledge of the fluorescence-light yield (FLY) is of paramount importance for the UHECR energy reconstruction. The MACFLY experiment was designed to perform absolute measurements of the air FLY and to study its properties. Here, we report the result of measurement of dry-air FLY induced by 50 GeV electromagnetic showers as a function of the shower age and as a function of the pressure. The experiment was performed at CERN using a SPS-electron-test-beam line. The result shows the air FLY is proportional to the energy deposited in air (Ed). The ratio FLY/Ed and its pressure dependence remain constant independently of shower age, and more generally, independently of the excitation source used (single-electron track or air shower).

  13. An Examination of Intervention Research with Secondary Students with EBD in Light of Common Core State Standards for Mathematics

    ERIC Educational Resources Information Center

    Mulcahy, Candace A.; Maccini, Paula; Wright, Kenneth; Miller, Jason

    2014-01-01

    In this review, the authors offer a critical analysis of published interventions for improving mathematics performance among middle and high school students with EBD in light of the Common Core State Standards. An exhaustive review of literature from 1975 to December 2012 yielded 20 articles that met criteria for inclusion. The authors analyzed…

  14. Core-shell heterostructured metal oxide arrays enable superior light-harvesting and hysteresis-free mesoscopic perovskite solar cells

    NASA Astrophysics Data System (ADS)

    Mahmood, Khalid; Swain, Bhabani Sankar; Amassian, Aram

    2015-07-01

    To achieve highly efficient mesoscopic perovskite solar cells (PSCs), the structure and properties of an electron transport layer (ETL) or material (ETM) have been shown to be of supreme importance. Particularly, the core-shell heterostructured mesoscopic ETM architecture has been recognized as a successful electrode design, because of its large internal surface area, superior light-harvesting efficiency and its ability to achieve fast charge transport. Here we report the successful fabrication of a hysteresis-free, 15.3% efficient PSC using vertically aligned ZnO nanorod/TiO2 shell (ZNR/TS) core-shell heterostructured ETMs for the first time. We have also added a conjugated polyelectrolyte polymer into the growth solution to promote the growth of high aspect ratio (AR) ZNRs and substantially improve the infiltration of the perovskite light absorber into the ETM. The PSCs based on the as-synthesized core-shell ZnO/TiO2 heterostructured ETMs exhibited excellent performance enhancement credited to the superior light harvesting capability, larger surface area, prolonged charge-transport pathways and lower recombination rate. The unique ETM design together with minimal hysteresis introduces core-shell ZnO/TiO2 heterostructures as a promising mesoscopic electrode approach for the fabrication of efficient PSCs.To achieve highly efficient mesoscopic perovskite solar cells (PSCs), the structure and properties of an electron transport layer (ETL) or material (ETM) have been shown to be of supreme importance. Particularly, the core-shell heterostructured mesoscopic ETM architecture has been recognized as a successful electrode design, because of its large internal surface area, superior light-harvesting efficiency and its ability to achieve fast charge transport. Here we report the successful fabrication of a hysteresis-free, 15.3% efficient PSC using vertically aligned ZnO nanorod/TiO2 shell (ZNR/TS) core-shell heterostructured ETMs for the first time. We have also added a

  15. Detection of Cherenkov light from air showers with Geiger-APDs

    NASA Astrophysics Data System (ADS)

    Otte, A.N. Britvich, I.; Biland, A.; Goebel, F.; Lorenz, E.; Pauss, F.; Renker, D.; Röser, U.; Schweizer, T.

    We have detected Cherenkov light from air showers with Geiger-mode APDs (G-APDs). G-APDs are novel semiconductor photon-detectors which offer several advantages compared to conventional photomultiplier tubes in the field of air shower detection. Folded with the Cherenkov spectrum the response of G-APDs is up to a factor of three higher if compared with classical photomultipliers. Moreover they offer high gain (~105-106) at low operation voltages (<100 V). Under operation they can withstand excessive and prolonged exposure to bright light and are also mechanical robust. Dark count rates of some G-APDs are below the level of light coming from the night sky. Furthermore G-APDs can be mass-produced which allows to considerably reduce the costs of these sensors. According to the present state of the development of G-APD they promise to be a major progress for gamma-ray astronomy. Here we report on the detection of Cherenkov light from air showers with G-APD. We discuss first test results and the advantages and problems of G-APDs in Cherenkov telescopes.

  16. 40 CFR 52.2301 - Federal compliance date for automobile and light-duty truck coating. Texas Air Control Board...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... and light-duty truck coating. Texas Air Control Board Regulation V (31 TAC chapter 115), control of air pollution from volatile organic compound, rule 115.191(1)(8)(A). 52.2301 Section 52.2301 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) APPROVAL...

  17. 40 CFR 52.2301 - Federal compliance date for automobile and light-duty truck coating. Texas Air Control Board...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... and light-duty truck coating. Texas Air Control Board Regulation V (31 TAC chapter 115), control of air pollution from volatile organic compound, rule 115.191(1)(8)(A). 52.2301 Section 52.2301 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) APPROVAL...

  18. 40 CFR 52.2301 - Federal compliance date for automobile and light-duty truck coating. Texas Air Control Board...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... and light-duty truck coating. Texas Air Control Board Regulation V (31 TAC chapter 115), control of air pollution from volatile organic compound, rule 115.191(1)(8)(A). 52.2301 Section 52.2301 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) APPROVAL...

  19. 40 CFR 52.2301 - Federal compliance date for automobile and light-duty truck coating. Texas Air Control Board...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... and light-duty truck coating. Texas Air Control Board Regulation V (31 TAC chapter 115), control of air pollution from volatile organic compound, rule 115.191(1)(8)(A). 52.2301 Section 52.2301 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) APPROVAL...

  20. 40 CFR 52.2301 - Federal compliance date for automobile and light-duty truck coating. Texas Air Control Board...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... and light-duty truck coating. Texas Air Control Board Regulation V (31 TAC chapter 115), control of air pollution from volatile organic compound, rule 115.191(1)(8)(A). 52.2301 Section 52.2301 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) APPROVAL...

  1. Triggering the volume phase transition of core-shell Au nanorod-microgel nanocomposites with light

    NASA Astrophysics Data System (ADS)

    Rodríguez-Fernández, Jessica; Fedoruk, Michael; Hrelescu, Calin; Lutich, Andrey A.; Feldmann, Jochen

    2011-06-01

    We have coated gold nanorods (NRs) with thermoresponsive microgel shells based on poly(N-isopropylacrylamide) (pNIPAM). We demonstrate by simultaneous laser-heating and optical extinction measurements that the Au NR cores can be simultaneously used as fast optothermal manipulators (switchers) and sensitive optical reporters of the microgel state in a fully externally controlled and reversible manner. We support our results with optical modeling based on the boundary element method and 3D numerical analysis on the temperature distribution. Briefly, we show that due to the sharp increase in refractive index resulting from the optothermally triggered microgel collapse, the longitudinal plasmon band of the coated Au NRs is significantly red-shifted. The optothermal control over the pNIPAM shell, and thereby over the optical response of the nanocomposite, is fully reversible and can be simply controlled by switching on and off a NIR heating laser. In contrast to bulk solution heating, we demonstrate that light-triggering does not compromise colloidal stability, which is of primary importance for the ultimate utilization of these types of nanocomposites as remotely controlled optomechanical actuators, for applications spanning from drug delivery to photonic crystals and nanoscale motion.

  2. Light-stimulated cargo release from a core-shell structured nanocomposite for site-specific delivery

    NASA Astrophysics Data System (ADS)

    Cai, Yun; Ling, Li; Li, Xiaofang; Chen, Meng; Su, Likai

    2015-03-01

    This paper reported a core-shell structured site-specific delivery system with a light switch triggered by low energy light (λ=510 nm). Its core was composed of supermagnetic Fe3O4 nanoparticles for magnetic guiding and targeting. Its outer shell consisted of mesoporous silica molecular sieve MCM-41 which offered highly ordered hexagonal tunnels for cargo capacity. A light switch N1-(4aH-cyclopenta[1,2-b:5,4-b‧]dipyridin-5(5aH)-ylidene)benzene-1,4-diamine (CBD) was covalently grafted into these hexagonal tunnels, serving as light stimuli acceptor with loading content of 1.1 μM/g. This composite was fully characterized and confirmed by SEM, TEM, XRD patterns, N2 adsorption/desorption, thermogravimetric analysis, IR, UV-vis absorption and emission spectra. Experimental data suggested that this composite had a core as wide as 150 nm and could be magnetically guided to specific sites. Its hexagonal tunnels were as long as 180 nm. Upon light stimuli of "on" and "off" states, controllable release was observed with short release time of ~900 s (90% capacity).

  3. Fabrication of a polyvinylidene difluoride fiber with a metal core and its application as directional air flow sensor

    NASA Astrophysics Data System (ADS)

    Bian, Yixiang; Liu, Rongrong; Hui, Shen

    2016-09-01

    We fabricated a sensitive air flow detector that mimic the sensing mechanism found at the tail of some insects. [see Y. Yang, A. Klein, H. Bleckmann and C. Liu, Appl. Phys. Lett. 99(2) (2011); J. J. Heys, T. Gedeon, B. C. Knott and Y. Kim, J. Biomech. 41(5), 977 (2008); J. Tao and X. Yu, Smart Mat. Struct. 21(11) (2012)]. Our bionic airflow sensor uses a polyvinylidene difluoride (PVDF) microfiber with a molybdenum core which we produced with the hot extrusion tensile method. The surface of the fiber is partially coated with conductive silver adhesive that serve as surface electrodes. A third electrode, the metal core is used to polarize polyvinylidene difluoride (PVDF) under the surface electrodes. The cantilever beam structure of the prepared symmetric electrodes of metal core piezoelectric fiber (SMPF) is used as the artificial hair airflow sensor. The surface electrodes are used to measure output voltage. Our theoretical and experimental results show that the SMPF responds fast to air flow changes, the output charge has an exponential correlation with airflow velocity and a cosine relation with the direction of airflow. Our bionic airflow sensor with directional sensing ability can also measure air flow amplitude. [see H. Droogendijk, R. G. P. Sanders and G. J. M. Krijnen, New J. Phys. 15 (2013)]. By using two surface electrodes, our sensing circuit further improves sensitivity.

  4. Development of Cockcroft-Walton Type High-Voltage DC Generator with RF Air-Core Transformer

    NASA Astrophysics Data System (ADS)

    Matsubara, Yoshio; Onishi, Kazuhiko; Muraoka, Takashi; Sugita, Michinobu; Kurisawa, Hideaki; Akita, Keizo; Hamano, Masaru; Nakazato, Hiroshi

    A Cockcroft-Walton (CW) type high-voltage DC generator is widely used for the electron processing system (EPS) which is applied for industrial purposes, such as radiation modification of polymers, medical product sterilization, and so on. The DC generator composes of the capacitors and diodes connected as cascade, and a step-up transformer. A new type high-voltage DC generator with RF air-core transformer used as the step-up transformer has been developed. The design concept of this air-core transformer, which is operated on the resonance condition between the inductance of the secondary coil and the stray capacitance of CW circuit, has been shown and the optimum coil structure has been proposed. Adapting the RF air-core transformer to DC300kV 100mA small CW circuit, the excellent performances have been successfully demonstrated. In this new CW circuit, it results in downsizing of the capacitors to operated at the higher frequency than the conventional one, and the approximately 40% reduction of the volume has been shown in the typically DC1MV 100mA generator.

  5. Climatic and insolation control on the high-resolution total air content in the NGRIP ice core

    NASA Astrophysics Data System (ADS)

    Eicher, Olivier; Baumgartner, Matthias; Schilt, Adrian; Schmitt, Jochen; Schwander, Jakob; Stocker, Thomas F.; Fischer, Hubertus

    2016-10-01

    Because the total air content (TAC) of polar ice is directly affected by the atmospheric pressure and temperature, its record in polar ice cores was initially considered as a proxy for past ice sheet elevation changes. However, the Antarctic ice core TAC record is known to also contain an insolation signature, although the underlying physical mechanisms are still a matter of debate. Here we present a high-resolution TAC record over the whole North Greenland Ice Core Project ice core, covering the last 120 000 years, which independently supports an insolation signature in Greenland. Wavelet analysis reveals a clear precession and obliquity signal similar to previous findings on Antarctic TAC, with a different insolation history. In our high-resolution record we also find a decrease of 4-6 % (4-5 mL kg-1) in TAC as a response to Dansgaard-Oeschger events (DO events). TAC starts to decrease in parallel to increasing Greenland surface temperature and slightly before CH4 reacts to the warming but also shows a two-step decline that lasts for several centuries into the warm interstadial. The TAC response is larger than expected considering only changes in air density by local temperature and atmospheric pressure as a driver, pointing to a transient firnification response caused by the accumulation-induced increase in the load on the firn at bubble close-off, while temperature changes deeper in the firn are still small.

  6. CfAIR2: Near-infrared Light Curves of 94 Type Ia Supernovae

    NASA Astrophysics Data System (ADS)

    Friedman, Andrew S.; Wood-Vasey, W. M.; Marion, G. H.; Challis, Peter; Mandel, Kaisey S.; Bloom, Joshua S.; Modjaz, Maryam; Narayan, Gautham; Hicken, Malcolm; Foley, Ryan J.; Klein, Christopher R.; Starr, Dan L.; Morgan, Adam; Rest, Armin; Blake, Cullen H.; Miller, Adam A.; Falco, Emilio E.; Wyatt, William F.; Mink, Jessica; Skrutskie, Michael F.; Kirshner, Robert P.

    2015-09-01

    CfAIR2 is a large, homogeneously reduced set of near-infrared (NIR) light curves (LCs) for Type Ia supernovae (SNe Ia) obtained with the 1.3 m Peters Automated InfraRed Imaging TELescope. This data set includes 4637 measurements of 94 SNe Ia and 4 additional SNe Iax observed from 2005 to 2011 at the Fred Lawrence Whipple Observatory on Mount Hopkins, Arizona. CfAIR2 includes {{JHK}}s photometric measurements for 88 normal and 6 spectroscopically peculiar SN Ia in the nearby universe, with a median redshift of z ˜ 0.021 for the normal SN Ia. CfAIR2 data span the range from -13 days to +127 days from B-band maximum. More than half of the LCs begin before the time of maximum, and the coverage typically contains ˜13-18 epochs of observation, depending on the filter. We present extensive tests that verify the fidelity of the CfAIR2 data pipeline, including comparison to the excellent data of the Carnegie Supernova Project. CfAIR2 contributes to a firm local anchor for SN cosmology studies in the NIR. Because SN Ia are more nearly standard candles in the NIR and are less vulnerable to the vexing problems of extinction by dust, CfAIR2 will help the SN cosmology community develop more precise and accurate extragalactic distance probes to improve our knowledge of cosmological parameters, including dark energy and its potential time variation.

  7. Light Transmission From Extended Air Showers Produced By Cosmic-Rays and Gamma-Rays

    NASA Astrophysics Data System (ADS)

    Taylor, S. F.; Abu-Zayyad, T.; Belov, K.; Cao, Z.; Chen, G.; Jui, C. C. H.; Kieda, D. B.; Matthews, J. N.; Salamon, M.; Sokolsky, P. V.; Smith, J. D.; Sommers, P.; Springer, R. W.; Stokes, B. T.; Thomas, S. B.; Wiencke, L. R.; Matthews, J. A. J.; Clay, R. W.; Dawson, B. R.; Simpson, K.; Bells, J.; Boyer, J.; Knapp, B.; Song, B. H.; Zhang, X. Z.; SDSS Collaboration; High Resolution Fly's Eye Collaboration; Telescope Array/U. Tokyo Collaboration

    1999-05-01

    Cosmic-ray and gamma-ray experiments that use the atmosphere as a calorimeter, such as the High Resolution Fly's Eye (HiRes) and the Telescope Array (TA), require understanding the transmission of the light from the air shower of particles produced by the cosmic-ray or gamma-ray striking the atmosphere. To better understand the scattering and transmission of light to the detectors, HiRes measures light from different calibrated sources. We compare scattered light from laser shots a few kilometers away from the two HiRes detectors, with direct light from stable portable light sources placed a few meters in front of the phototubes. We use two HiRes detectors to study and isolate contributions to fluctuations of the measured light. These contributions include fluctuations in the source intensity, the night sky background, scattering and transmission of the laser beam, the phototubes and electronics, and photostatistics. The High Resolution Fly's Eye Collaboration gratefully acknowledges the support of the US National Science Foundation, DOE, the US Army's Dugway Proving Grounds, and the support of our member universities.

  8. Face Sheet/Core Disbond Growth in Honeycomb Sandwich Panels Subjected to Ground-Air-Ground Pressurization and In-Plane Loading

    NASA Technical Reports Server (NTRS)

    Chen, Zhi M.; Krueger, Ronald; Rinker, Martin

    2015-01-01

    Typical damage modes in light honeycomb sandwich structures include face sheet/core disbonding and core fracture, both of which can pose a threat to the structural integrity of a component. These damage modes are of particular interest to aviation certification authorities since several in-service occurrences, such as rudder structural failure and other control surface malfunctions, have been attributed to face sheet/core disbonding. Extensive studies have shown that face sheet/core disbonding and core fracture can lead to damage propagation caused by internal pressure changes in the core. The increasing use of composite sandwich construction in aircraft applications makes it vitally important to understand the effect of ground-air-ground (GAG) cycles and conditions such as maneuver and gust loads on face sheet/core disbonding. The objective of the present study was to use a fracture mechanics based approach developed earlier to evaluate the loading at the disbond front caused by ground-air-ground pressurization and in-plane loading. A honeycomb sandwich panel containing a circular disbond at one face sheet/core interface was modeled with three-dimensional (3D) solid finite elements. The disbond was modeled as a discrete discontinuity and the strain energy release rate along the disbond front was computed using the Virtual Crack Closure Technique (VCCT). Special attention was paid to the pressure-deformation coupling which can decrease the pressure load within the disbonded sandwich section significantly when the structure is highly deformed. The commercial finite element analysis software, Abaqus/Standard, was used for the analyses. The recursive pressure-deformation coupling problem was solved by representing the entrapped air in the honeycomb cells as filled cavities in Abaqus/Standard. The results show that disbond size, face sheet thickness and core thickness are important parameters that determine crack tip loading at the disbond front. Further, the pressure

  9. Air

    MedlinePlus

    ... do to protect yourself from dirty air . Indoor air pollution and outdoor air pollution Air can be polluted indoors and it can ... this chart to see what things cause indoor air pollution and what things cause outdoor air pollution! Indoor ...

  10. Performance of Introducing Outdoor Cold Air for Cooling a Plant Production System with Artificial Light.

    PubMed

    Wang, Jun; Tong, Yuxin; Yang, Qichang; Xin, Min

    2016-01-01

    The commercial use of a plant production system with artificial light (PPAL) is limited by its high initial construction and operation costs. The electric-energy consumed by heat pumps, applied mainly for cooling, accounts for 15-35% of the total electric-energy used in a PPAL. To reduce the electric-energy consumption, an air exchanger with low capacity (180 W) was used for cooling by introducing outdoor cold air. In this experiment, the indoor air temperature in two PPALs (floor area: 6.2 m(2) each) was maintained at 25 and 20°C during photoperiod and dark period, respectively, for lettuce production. A null CO2 balance enrichment method was used in both PPALs. In one PPAL (PPALe), an air exchanger (air flow rate: 250 m(3)·h(-1)) was used along with a heat pump (cooling capacity: 3.2 kW) to maintain the indoor air temperature at the set-point. The other PPAL (PPALc) with only a heat pump (cooling capacity: 3.2 kW) was used for reference. Effects of introducing outdoor cold air on energy use efficiency, coefficient of performance (COP), electric-energy consumption for cooling and growth of lettuce were investigated. The results show that: when the air temperature difference between indoor and outdoor ranged from 20.2 to 30.0°C: (1) the average energy use efficiency of the air exchanger was 2.8 and 3.4 times greater than the COP of the heat pumps in the PPALe and PPALc, respectively; (2) hourly electric-energy consumption for cooling in the PPALe reduced by 15.8-73.7% compared with that in the PPALc; (3) daily supply of CO2 in the PPALe reduced from 0.15 to 0.04 kg compared with that in the PPALc with the outdoor air temperature ranging from -5.6 to 2.7°C; (4) no significant difference in lettuce growth was observed in both PPALs. The results indicate that using air exchanger to introduce outdoor cold air should be considered as an effective way to reduce electric-energy consumption for cooling with little effects on plant growth in a PPAL. PMID:27066012

  11. Performance of Introducing Outdoor Cold Air for Cooling a Plant Production System with Artificial Light

    PubMed Central

    Wang, Jun; Tong, Yuxin; Yang, Qichang; Xin, Min

    2016-01-01

    The commercial use of a plant production system with artificial light (PPAL) is limited by its high initial construction and operation costs. The electric-energy consumed by heat pumps, applied mainly for cooling, accounts for 15–35% of the total electric-energy used in a PPAL. To reduce the electric-energy consumption, an air exchanger with low capacity (180 W) was used for cooling by introducing outdoor cold air. In this experiment, the indoor air temperature in two PPALs (floor area: 6.2 m2 each) was maintained at 25 and 20°C during photoperiod and dark period, respectively, for lettuce production. A null CO2 balance enrichment method was used in both PPALs. In one PPAL (PPALe), an air exchanger (air flow rate: 250 m3·h−1) was used along with a heat pump (cooling capacity: 3.2 kW) to maintain the indoor air temperature at the set-point. The other PPAL (PPALc) with only a heat pump (cooling capacity: 3.2 kW) was used for reference. Effects of introducing outdoor cold air on energy use efficiency, coefficient of performance (COP), electric-energy consumption for cooling and growth of lettuce were investigated. The results show that: when the air temperature difference between indoor and outdoor ranged from 20.2 to 30.0°C: (1) the average energy use efficiency of the air exchanger was 2.8 and 3.4 times greater than the COP of the heat pumps in the PPALe and PPALc, respectively; (2) hourly electric-energy consumption for cooling in the PPALe reduced by 15.8–73.7% compared with that in the PPALc; (3) daily supply of CO2 in the PPALe reduced from 0.15 to 0.04 kg compared with that in the PPALc with the outdoor air temperature ranging from −5.6 to 2.7°C; (4) no significant difference in lettuce growth was observed in both PPALs. The results indicate that using air exchanger to introduce outdoor cold air should be considered as an effective way to reduce electric-energy consumption for cooling with little effects on plant growth in a PPAL. PMID:27066012

  12. Solid core dipoles and switching power supplies: Lower cost light sources?

    SciTech Connect

    Benesch, Jay; Philip, Sarin

    2015-05-05

    As a result of improvements in power semiconductors, moderate frequency switching supplies can now provide the hundreds of amps typically required by accelerators with zero-to-peak noise in the kHz region ~ 0.06% in current or voltage mode. Modeling was undertaken using a finite electromagnetic program to determine if eddy currents induced in the solid steel of CEBAF magnets and small supplemental additions would bring the error fields down to the 5ppm level needed for beam quality. The expected maximum field of the magnet under consideration is 0.85 T and the DC current required to produce that field is used in the calculations. An additional 0.1% current ripple is added to the DC current at discrete frequencies 360 Hz, 720 Hz or 7200 Hz. Over the region of the pole within 0.5% of the central integrated BdL the resulting AC field changes can be reduced to less than 1% of the 0.1% input ripple for all frequencies, and a sixth of that at 7200 Hz. Doubling the current, providing 1.5 T central field, yielded the same fractional reduction in ripple at the beam for the cases checked. A small dipole was measured at 60, 120, 360 and 720 Hz in two conditions and the results compared to the larger model for the latter two frequencies with surprisingly good agreement. Thus, for light sources with aluminum vacuum vessels and full energy linac injection, the combination of solid core dipoles and switching power supplies may result in significant cost savings.

  13. Facile synthesis of Ag@CeO2 core-shell plasmonic photocatalysts with enhanced visible-light photocatalytic performance.

    PubMed

    Wu, Linen; Fang, Siman; Ge, Lei; Han, Changcun; Qiu, Ping; Xin, Yongji

    2015-12-30

    Novel Ag@CeO2 core-shell nanostructures with well-controlled shape and shell thickness were successfully synthesized via a green and facile template-free approach in aqueous solution. As-prepared samples were characterized by high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), ultraviolet-visible diffuse reflection spectroscopy (DRS), electron spin resonance (ESR) and photoluminescence spectroscopy (PL). The structures with different core shapes and controllable shell thickness exhibited unique optical properties. It is found that the nanoscale Ag@CeO2 core-shell photocatalysts exhibit significantly enhanced photocatalytic activities in the O2 evolution and MB dye degradation compared to pure CeO2 nanoparticals. The enhancement in photocatalytic activities can be ascribed to the localized surface plasmon resonance (SPR) of Ag cores. Moreover, larger active interfacial areas and contact between metal/semiconductor in the core-shell structure facilitate transfer of charge carriers and prolong lifetime of photogenerated electron-hole pairs. It is expected that the Ag@CeO2 core-shell structure may have great potential in a wider range of light-harvesting applications.

  14. Glacial-interglacial dynamics of Antarctic firn columns: comparison between simulations and ice core air-?15N measurements

    NASA Astrophysics Data System (ADS)

    Capron, E.; Landais, A.; Buiron, D.; Cauquoin, A.; Chappellaz, J. A.; Debret, M.; Jouzel, J.; Leuenberger, M.; Martinerie, P.; Masson-Delmotte, V.; Mulvaney, R.; Parrenin, F.; Prié, F.

    2013-12-01

    Correct estimation of the firn lock-in depth is essential for correctly linking gas and ice chronologies in ice core studies. Here, two approaches to constrain the firn depth evolution in Antarctica are presented over the last deglaciation: outputs of a firn densification model, and measurements of δ15N of N2 in air trapped in ice core, assuming that δ15N is only affected by gravitational fractionation in the firn column. Since the firn densification process is largely governed by surface temperature and accumulation rate, we have investigated four ice cores drilled in coastal (Berkner Island, BI, and James Ross Island, JRI) and semi-coastal (TALDICE and EPICA Dronning Maud Land, EDML) Antarctic regions. Combined with available ice core air- δ15N measurements from the EPICA Dome C (EDC) site, the studied regions encompass a large range of surface accumulation rates and temperature conditions. Our δ15N profiles reveal a heterogeneous response of the firn structure to glacial-interglacial climatic changes. While firn densification simulations correctly predict TALDICE δ15N variations, they systematically fail to capture the large millennial-scale δ15N variations measured at BI and the δ15N glacial levels measured at JRI and EDML - a mismatch previously reported for central East Antarctic ice cores. New constraints of the EDML gas-ice depth offset during the Laschamp event (41 ka) and the last deglaciation do not favour the hypothesis of a large convective zone within the firn as the explanation of the glacial firn model- δ15N data mismatch for this site. While we could not conduct an in-depth study of the influence of impurities in snow for firnification from the existing datasets, our detailed comparison between the δ15N profiles and firn model simulations under different temperature and accumulation rate scenarios suggests that the role of accumulation rate may have been underestimated in the current description of firnification models.

  15. Glacial-interglacial dynamics of Antarctic firn columns: comparison between simulations and ice core air-δ15N measurements

    NASA Astrophysics Data System (ADS)

    Capron, E.; Landais, A.; Buiron, D.; Cauquoin, A.; Chappellaz, J.; Debret, M.; Jouzel, J.; Leuenberger, M.; Martinerie, P.; Masson-Delmotte, V.; Mulvaney, R.; Parrenin, F.; Prié, F.

    2013-05-01

    Correct estimation of the firn lock-in depth is essential for correctly linking gas and ice chronologies in ice core studies. Here, two approaches to constrain the firn depth evolution in Antarctica are presented over the last deglaciation: outputs of a firn densification model, and measurements of δ15N of N2 in air trapped in ice core, assuming that δ15N is only affected by gravitational fractionation in the firn column. Since the firn densification process is largely governed by surface temperature and accumulation rate, we have investigated four ice cores drilled in coastal (Berkner Island, BI, and James Ross Island, JRI) and semi-coastal (TALDICE and EPICA Dronning Maud Land, EDML) Antarctic regions. Combined with available ice core air-δ15N measurements from the EPICA Dome C (EDC) site, the studied regions encompass a large range of surface accumulation rates and temperature conditions. Our δ15N profiles reveal a heterogeneous response of the firn structure to glacial-interglacial climatic changes. While firn densification simulations correctly predict TALDICE δ15N variations, they systematically fail to capture the large millennial-scale δ15N variations measured at BI and the δ15N glacial levels measured at JRI and EDML - a mismatch previously reported for central East Antarctic ice cores. New constraints of the EDML gas-ice depth offset during the Laschamp event (~41 ka) and the last deglaciation do not favour the hypothesis of a large convective zone within the firn as the explanation of the glacial firn model-δ15N data mismatch for this site. While we could not conduct an in-depth study of the influence of impurities in snow for firnification from the existing datasets, our detailed comparison between the δ15N profiles and firn model simulations under different temperature and accumulation rate scenarios suggests that the role of accumulation rate may have been underestimated in the current description of firnification models.

  16. Carbon and other light element contents in the Earth’s core based on first-principles molecular dynamics

    PubMed Central

    Zhang, Yigang; Yin, Qing-Zhu

    2012-01-01

    Carbon (C) is one of the candidate light elements proposed to account for the density deficit of the Earth’s core. In addition, C significantly affects siderophile and chalcophile element partitioning between metal and silicate and thus the distribution of these elements in the Earth’s core and mantle. Derivation of the accretion and core–mantle segregation history of the Earth requires, therefore, an accurate knowledge of the C abundance in the Earth’s core. Previous estimates of the C content of the core differ by a factor of ∼20 due to differences in assumptions and methods, and because the metal–silicate partition coefficient of C was previously unknown. Here we use two-phase first-principles molecular dynamics to derive this partition coefficient of C between liquid iron and silicate melt. We calculate a value of 9 ± 3 at 3,200 K and 40 GPa. Using this partition coefficient and the most recent estimates of bulk Earth or mantle C contents, we infer that the Earth’s core contains 0.1–0.7 wt% of C. Carbon thus plays a moderate role in the density deficit of the core and in the distribution of siderophile and chalcophile elements during core–mantle segregation processes. The partition coefficients of nitrogen (N), hydrogen, helium, phosphorus, magnesium, oxygen, and silicon are also inferred and found to be in close agreement with experiments and other geochemical constraints. Contents of these elements in the core derived from applying these partition coefficients match those derived by using the cosmochemical volatility curve and geochemical mass balance arguments. N is an exception, indicating its retention in a mantle phase instead of in the core. PMID:23150591

  17. Evaluation of dust-related health hazards associated with air coring at G-Tunnel, Nevada Test Site

    SciTech Connect

    Skaggs, B.J.; Ortiz, L.W.; Burton, D.J.; Isom, B.L.; Vigil, E.A.

    1991-03-01

    The Yucca Mountain Project was established to evaluate the potential for storing high-level radioactive wastes in geologic formations. Hydrologists recommended that drilling or coring in support of characterization tests be performed dry. Dry drilling, or air coring, presents a concern about health protection for the drilling personnel. The rock generally has a high silica content, and natural zeolites are abundant. Some zeolites are fibrous, leading to concerns that inhalation may result in asbestos-like lung diseases. An industrial hygiene study (IH) was conducted as part of an air coring technical feasibility test. The IH study found the potential for exposures to airborne silica and nuisance dusts to be within regulatory requirements and determined the commercial dust control equipment monitored to be effective when used in conjunction with a good area ventilation system and sound IH practices. Fibrous zeolites were not detected. Recommendations for the Yucca Mountain studies are (1) dust collection and control equipment equivalent or superior to that monitored must be used for any dry drilling activity and must be used with good general dilution ventilation and local exhaust ventilation provided on major emission sources; (2) good industrial hygiene work practices must be implemented, including monitoring any area where zeolitic fibers are suspect; and (3) a study should be conducted to determine the biological effects of the fibrous zeolite, mordenite. 25 refs., 17 figs., 14 tabs.

  18. Highly active and durable core-corona structured bifunctional catalyst for rechargeable metal-air battery application.

    PubMed

    Chen, Zhu; Yu, Aiping; Higgins, Drew; Li, Hui; Wang, Haijiang; Chen, Zhongwei

    2012-04-11

    A new class of core-corona structured bifunctional catalyst (CCBC) consisting of lanthanum nickelate centers supporting nitrogen-doped carbon nanotubes (NCNT) has been developed for rechargeable metal-air battery application. The nanostructured design of the catalyst allows the core and corona to catalyze the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR), respectively. These materials displayed exemplary OER and ORR activity through half-cell testing, comparable to state of the art commercial lanthanum nickelate (LaNiO(3)) and carbon-supported platinum (Pt/C), with added bifunctional capabilities allowing metal-air battery rechargeability. LaNiO(3) and Pt/C are currently the most accepted benchmark electrocatalyst materials for the OER and ORR, respectively; thus with comparable activity toward both of these reactions, CCBC are presented as a novel, inexpensive catalyst component for the cathode of rechargeable metal-air batteries. Moreover, after full-range degradation testing (FDT) CCBC retained excellent activity, retaining 3 and 13 times greater ORR and OER current upon comparison to state of the art Pt/C. Zinc-air battery performances of CCBC is in good agreement with the half-cell experiments with this bifunctional electrocatalyst displaying high activity and stability during battery discharge, charge, and cycling processes. Owing to its outstanding performance toward both the OER and ORR, comparable with the highest performing commercial catalysts to date for each of the respective reaction, coupled with high stability and rechargeability, CCBC is presented as a novel class of bifunctional catalyst material that is very applicable to future generation rechargeable metal-air batteries.

  19. Highly active and durable core-corona structured bifunctional catalyst for rechargeable metal-air battery application.

    PubMed

    Chen, Zhu; Yu, Aiping; Higgins, Drew; Li, Hui; Wang, Haijiang; Chen, Zhongwei

    2012-04-11

    A new class of core-corona structured bifunctional catalyst (CCBC) consisting of lanthanum nickelate centers supporting nitrogen-doped carbon nanotubes (NCNT) has been developed for rechargeable metal-air battery application. The nanostructured design of the catalyst allows the core and corona to catalyze the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR), respectively. These materials displayed exemplary OER and ORR activity through half-cell testing, comparable to state of the art commercial lanthanum nickelate (LaNiO(3)) and carbon-supported platinum (Pt/C), with added bifunctional capabilities allowing metal-air battery rechargeability. LaNiO(3) and Pt/C are currently the most accepted benchmark electrocatalyst materials for the OER and ORR, respectively; thus with comparable activity toward both of these reactions, CCBC are presented as a novel, inexpensive catalyst component for the cathode of rechargeable metal-air batteries. Moreover, after full-range degradation testing (FDT) CCBC retained excellent activity, retaining 3 and 13 times greater ORR and OER current upon comparison to state of the art Pt/C. Zinc-air battery performances of CCBC is in good agreement with the half-cell experiments with this bifunctional electrocatalyst displaying high activity and stability during battery discharge, charge, and cycling processes. Owing to its outstanding performance toward both the OER and ORR, comparable with the highest performing commercial catalysts to date for each of the respective reaction, coupled with high stability and rechargeability, CCBC is presented as a novel class of bifunctional catalyst material that is very applicable to future generation rechargeable metal-air batteries. PMID:22372510

  20. Nonlinear compression of high energy fiber amplifier pulses in air-filled hypocycloid-core Kagome fiber.

    PubMed

    Guichard, Florent; Giree, Achut; Zaouter, Yoann; Hanna, Marc; Machinet, Guillaume; Debord, Benoît; Gérôme, Frédéric; Dupriez, Pascal; Druon, Frédéric; Hönninger, Clemens; Mottay, Eric; Benabid, Fetah; Georges, Patrick

    2015-03-23

    We report on the generation of 34 fs and 50 µJ pulses from a high energy fiber amplifier system with nonlinear compression in an air-filled hypocycloid-core Kagome fiber. The unique properties of such fibers allow bridging the gap between solid core fibers-based and hollow capillary-based post-compression setups, thereby operating with pulse energies obtained with current state-of-the-art fiber systems. The overall transmission of the compression setup is over 70%. Together with Yb-doped fiber amplifier technologies, Kagome fibers therefore appear as a promising tool for efficient generation of pulses with durations below 50 fs, energies ranging from 10 to several hundreds of µJ, and high average powers.

  1. Design and fabrication of a metal core PVDF fiber for an air flow sensor

    NASA Astrophysics Data System (ADS)

    Bian, Yixiang; Liu, Rongrong; Huang, Xiaomei; Hong, Jin; Huang, Huiyu; Hui, Shen

    2015-10-01

    To track prey or avoid predators, many arthropods can detect variations in airflow and pressure gradients using an array of very thin and sensitive filiform hairs. In this study, metal core piezoelectric poly(vinylidene fluoride) (PVDF) fibers were prepared to mimic such hair sensors. The flexibility of the fibers was very good, which was helpful for overcoming the typical brittleness of piezoelectric ceramic fibers. At the same time, the diameter of the fibers was very small (down to 50 μm in diameter). In order to mimic the insects’ hairs to the maximum extent, which was expected to greatly improve the sensitivity of such PVDF fiber-based sensors, a feasible process to prepare and extract electrodes on the surface of the fibers had to be developed. Compared with stainless steel filament-core fibers, the molybdenum filament-core PVDF fibers were easy to stretch. The molybdenum filament was then covered by a cylindrical PVDF layer with a diameter of 400 μm. One half of the longitudinal surface of the fibers was spray-coated with a conductive silver adhesive. The metal core was then used as one electrode, and the conductive silver adhesive was used as the other electrode. After polarization, a single metal-core PVDF fiber could be used as an airflow sensor. The surface structure and the sections of the PVDF fiber were analyzed by scanning electron microscopy. The results of the mechanical stretching tests showed that the metal core greatly enhanced the mechanical properties of the PVDF fibers. X-ray diffraction revealed that the greater the stretching ratio, the higher the α-to-β-phase conversion rate during the preparation of the PVDF fibers. A single metal-core PVDF fiber was used as a bionic airflow sensor, and a mechanical model of this sensor was derived. The airflow sensing capability of the PVDF fiber was experimentally confirmed in a miniature wind tunnel. The results showed that a cantilevered metal-core PVDF fiber is capable of detecting the range

  2. Selection of Light Duty Truck Engine Air Systems Using Virtual Lab Tests

    SciTech Connect

    Zhang, Houshun

    2000-08-20

    An integrated development approach using seasoned engine technology methodologies, virtual lab parametric investigations, and selected hardware verification tests reflects today's state-of-the-art R&D trends. This presentation will outline such a strategy. The use of this ''Wired'' approach results in substantial reduction in the development cycle time and hardware iterations. An example showing the virtual lab application for a viable design of the air-exhaust-turbocharger system of a light duty truck engine for personal transportation will be presented.

  3. Index matching at the nanoscale: light scattering by core-shell Si/SiO x nanowires.

    PubMed

    Leiterer, Christian; Brönstrup, Gerald; Jahr, Norbert; Talkenberg, Florian; Radnóczi, György Zoltán; Pécz, Béla; Christiansen, Silke; Sivakov, Vladimir

    2016-10-28

    Silicon nanowires (SiNWs) show strong resonant wavelength enhancement in terms of absorption as well as scattering of light. However, in most optoelectronic device concepts the SiNWs should be surrounded by a contact layer. Ideally, such a layer can also act as an index matching layer which could nearly halve the strong reflectance of light by silicon. Our results show that this reduction can be overcome at the nanometer scale, i.e. SiNWs embedded in a silica (SiO x ) layer can not only maintain their high scattering cross sections but also their strong polarization dependent scattering. Such effects can be useful for light harvesting or optoelectronic applications. Moreover, we show that it is possible to optically determine the diameters of the embedded nanoscale silicon (Si) cores. PMID:27655170

  4. Index matching at the nanoscale: light scattering by core-shell Si/SiO x nanowires

    NASA Astrophysics Data System (ADS)

    Leiterer, Christian; Brönstrup, Gerald; Jahr, Norbert; Talkenberg, Florian; Zoltán Radnóczi, György; Pécz, Béla; Christiansen, Silke; Sivakov, Vladimir

    2016-10-01

    Silicon nanowires (SiNWs) show strong resonant wavelength enhancement in terms of absorption as well as scattering of light. However, in most optoelectronic device concepts the SiNWs should be surrounded by a contact layer. Ideally, such a layer can also act as an index matching layer which could nearly halve the strong reflectance of light by silicon. Our results show that this reduction can be overcome at the nanometer scale, i.e. SiNWs embedded in a silica (SiO x ) layer can not only maintain their high scattering cross sections but also their strong polarization dependent scattering. Such effects can be useful for light harvesting or optoelectronic applications. Moreover, we show that it is possible to optically determine the diameters of the embedded nanoscale silicon (Si) cores.

  5. Damage-free single-mode transmission of deep-UV light in hollow-core PCF.

    PubMed

    Gebert, F; Frosz, M H; Weiss, T; Wan, Y; Ermolov, A; Joly, N Y; Schmidt, P O; Russell, P St J

    2014-06-30

    Transmission of UV light with high beam quality and pointing stability is desirable for many experiments in atomic, molecular and optical physics. In particular, laser cooling and coherent manipulation of trapped ions with transitions in the UV require stable, single-mode light delivery. Transmitting even ~2 mW CW light at 280 nm through silica solid-core fibers has previously been found to cause transmission degradation after just a few hours due to optical damage. We show that photonic crystal fiber of the kagomé type can be used for effectively single-mode transmission with acceptable loss and bending sensitivity. No transmission degradation was observed even after >100 hours of operation with 15 mW CW input power. In addition it is shown that implementation of the fiber in a trapped ion experiment increases the coherence time of the internal state transfer due to an increase in beam pointing stability.

  6. Index matching at the nanoscale: light scattering by core-shell Si/SiO x nanowires.

    PubMed

    Leiterer, Christian; Brönstrup, Gerald; Jahr, Norbert; Talkenberg, Florian; Radnóczi, György Zoltán; Pécz, Béla; Christiansen, Silke; Sivakov, Vladimir

    2016-10-28

    Silicon nanowires (SiNWs) show strong resonant wavelength enhancement in terms of absorption as well as scattering of light. However, in most optoelectronic device concepts the SiNWs should be surrounded by a contact layer. Ideally, such a layer can also act as an index matching layer which could nearly halve the strong reflectance of light by silicon. Our results show that this reduction can be overcome at the nanometer scale, i.e. SiNWs embedded in a silica (SiO x ) layer can not only maintain their high scattering cross sections but also their strong polarization dependent scattering. Such effects can be useful for light harvesting or optoelectronic applications. Moreover, we show that it is possible to optically determine the diameters of the embedded nanoscale silicon (Si) cores.

  7. Monitoring of Plant Light/Dark Cycles Using Air-coupled Ultrasonic Spectroscopy

    NASA Astrophysics Data System (ADS)

    Fariñas, M. D.; Sancho-Knapik, D.; Peguero-Pina, J.; Gil-Pelegrín, E.; Álvarez-Arenas, T. E. G.

    This work presents the application of a technique based on the excitation, sensing and spectral analysis of leaves thickness resonances using air-coupled and wide-band ultrasound to monitor variations in leaves properties due to the plant response along light/dark cycles. The main features of these resonances are determined by the tautness of the cells walls in such a way that small modifications produced by variations in the transpiration rate, stomata aperture or water potential have a direct effect on the thickness resonances that can be measured in a completely non-invasive and contactless way. Results show that it is possible to monitor leaves changes due to variations in light intensity along the diurnal cycle, moreover, the technique reveals differences in the leaf response for different species and also within the same species but for specimens grown under different conditions that present different cell structures at the tissue level.

  8. MEASUREMENT OF EFFECTIVE AIR DIFFUSION COEFFICIENTS FOR TRICHLOROETHENE IN UNDISTURBED SOIL CORES. (R826162)

    EPA Science Inventory

    Abstract

    In this study, we measure effective diffusion coefficients for trichloroethene in undisturbed soil samples taken from Picatinny Arsenal, New Jersey. The measured effective diffusion coefficients ranged from 0.0053 to 0.0609 cm2/s over a range of air...

  9. Effect of silane type and air-drying temperature on bonding fiber post to composite core and resin cement.

    PubMed

    de Rosatto, Camila Maria Peres; Roscoe, Marina Guimarães; Novais, Veridiana Resende; Menezes, Murilo de Sousa; Soares, Carlos José

    2014-01-01

    This study evaluated the influence of silane type and temperature of silane application on push-out bond strength between fiberglass posts with composite resin core and resin cement. One hundred and sixty fiberglass posts (Exacto, Angelus) had the surface treated with hydrogen peroxide 24%. Posts were divided in 8 groups according to two study factors: air-drying temperature after silane application (room temperature and 60 ºC) and silane type: three pre-hydrolyzed--Silano (Angelus), Prosil (FGM), RelyX Ceramic Primer (3M ESPE) and one two-component silane--Silane Coupling Agent (Dentsply). The posts (n=10) for testing the bond strength between post and composite core were centered on a cylindrical plastic matrix and composite resin (Filtek Z250 XT, 3M ESPE) that was incrementally inserted and photoactivated. Eighty bovine incisor roots (n=10) were prepared for testing the bond strength between post and resin cement (RelyX U100, 3M ESPE) and received the fiberglass posts. Push-out test was used to measure the bond strength. Data were analyzed by two-way ANOVA followed by Tukey's test (α=0.05). ANOVA revealed that temperature and silane had no influence on bond strength between composite core and post. However, for bond strength between post and resin cement, the temperature increase resulted in a better performance for Silane Coupling Agent, Silano and RelyX Ceramic Primer. At room temperature Silane Coupling Agent showed the lowest bond strength. Effect of the warm air-drying is dependent on the silane composition. In conclusion, the use of silane is influenced by wettability of resinous materials and pre-hydrolyzed silanes are more stable compared with the two-bottle silane. PMID:25252257

  10. Effect of silane type and air-drying temperature on bonding fiber post to composite core and resin cement.

    PubMed

    de Rosatto, Camila Maria Peres; Roscoe, Marina Guimarães; Novais, Veridiana Resende; Menezes, Murilo de Sousa; Soares, Carlos José

    2014-01-01

    This study evaluated the influence of silane type and temperature of silane application on push-out bond strength between fiberglass posts with composite resin core and resin cement. One hundred and sixty fiberglass posts (Exacto, Angelus) had the surface treated with hydrogen peroxide 24%. Posts were divided in 8 groups according to two study factors: air-drying temperature after silane application (room temperature and 60 ºC) and silane type: three pre-hydrolyzed--Silano (Angelus), Prosil (FGM), RelyX Ceramic Primer (3M ESPE) and one two-component silane--Silane Coupling Agent (Dentsply). The posts (n=10) for testing the bond strength between post and composite core were centered on a cylindrical plastic matrix and composite resin (Filtek Z250 XT, 3M ESPE) that was incrementally inserted and photoactivated. Eighty bovine incisor roots (n=10) were prepared for testing the bond strength between post and resin cement (RelyX U100, 3M ESPE) and received the fiberglass posts. Push-out test was used to measure the bond strength. Data were analyzed by two-way ANOVA followed by Tukey's test (α=0.05). ANOVA revealed that temperature and silane had no influence on bond strength between composite core and post. However, for bond strength between post and resin cement, the temperature increase resulted in a better performance for Silane Coupling Agent, Silano and RelyX Ceramic Primer. At room temperature Silane Coupling Agent showed the lowest bond strength. Effect of the warm air-drying is dependent on the silane composition. In conclusion, the use of silane is influenced by wettability of resinous materials and pre-hydrolyzed silanes are more stable compared with the two-bottle silane.

  11. White polymer light-emitting diodes based on star-shaped polymers with an orange dendritic phosphorescent core.

    PubMed

    Zhu, Minrong; Li, Yanhu; Cao, Xiaosong; Jiang, Bei; Wu, Hongbin; Qin, Jingui; Cao, Yong; Yang, Chuluo

    2014-12-01

    A series of new star-shaped polymers with a triphenylamine-based iridium(III) dendritic complex as the orange-emitting core and poly(9,9-dihexylfluorene) (PFH) chains as the blue-emitting arms is developed towards white polymer light-emitting diodes (WPLEDs). By fine-tuning the content of the orange phosphor, partial energy transfer and charge trapping from the blue backbone to the orange core is realized to achieve white light emission. Single-layer WPLEDs with the configuration of ITO (indium-tin oxide)/poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS)/polymer/CsF/Al exhibit a maximum current efficiency of 1.69 cd A(-1) and CIE coordinates of (0.35, 0.33), which is very close to the pure white-light point of (0.33, 0.33). To the best of our knowledge, this is the first report on star-shaped white-emitting single polymers that simultaneously consist of fluorescent and phosphorescent species.

  12. Self-focusing in air with phase-stabilized few-cycle light pulses.

    PubMed

    Laban, D E; Wallace, W C; Glover, R D; Sang, R T; Kielpinski, D

    2010-05-15

    We investigate the nonlinear optical phenomenon of self-focusing in air with phase-stabilized few-cycle light pulses. This investigation looks at the role of the carrier-envelope phase by observing a filament in air, a nonlinear phenomenon that can be utilized for few-cycle pulse compression [Appl. Phys. B79, 673 (2004)]. We were able to measure the critical power for self-focusing in air to be 18+/-1 GW for a 6.3 fs pulse centered at 800 nm. Using this value and a basic first-order theory, we predicted that the self-focusing distance should deviate by 790 mum as the carrier-envelope phase is shifted from 0 to pi/2 rad. In contrast, the experimental results showed no deviation in the focus distance with a 3sigma upper limit of 180 mum. These counterintuitive results show the need for further study of self-focusing dynamics in the few-cycle regime.

  13. Aerosol Light Absorption and Scattering Assessments and the Impact of City Size on Air Pollution

    NASA Astrophysics Data System (ADS)

    Paredes-Miranda, Guadalupe

    The general problem of urban pollution and its relation to the city population is examined in this dissertation. A simple model suggests that pollutant concentrations should scale approximately with the square root of city population. This model and its experimental evaluation presented here serve as important guidelines for urban planning and attainment of air quality standards including the limits that air pollution places on city population. The model was evaluated using measurements of air pollution. Optical properties of aerosol pollutants such as light absorption and scattering plus chemical species mass concentrations were measured with a photoacoustic spectrometer, a reciprocal nephelometer, and an aerosol mass spectrometer in Mexico City in the context of the multinational project "Megacity Initiative: Local And Global Research Observations (MILAGRO)" in March 2006. Aerosol light absorption and scattering measurements were also obtained for Reno and Las Vegas, NV USA in December 2008-March 2009 and January-February 2003, respectively. In all three cities, the morning scattering peak occurs a few hours later than the absorption peak due to the formation of secondary photochemically produced aerosols. In particular, for Mexico City we determined the fraction of photochemically generated secondary aerosols to be about 75% of total aerosol mass concentration at its peak near midday. The simple 2-d box model suggests that commonly emitted primary air pollutant (e.g., black carbon) mass concentrations scale approximately as the square root of the urban population. This argument extends to the absorption coefficient, as it is approximately proportional to the black carbon mass concentration. Since urban secondary pollutants form through photochemical reactions involving primary precursors, in linear approximation their mass concentration also should scale with the square root of population. Therefore, the scattering coefficient, a proxy for particulate matter

  14. A dual-emitting core-shell carbon dot-silica-phosphor composite for white light emission

    NASA Astrophysics Data System (ADS)

    Chen, Yonghao; Lei, Bingfu; Zheng, Mingtao; Zhang, Haoran; Zhuang, Jianle; Liu, Yingliang

    2015-11-01

    A unique dual-emitting core-shell carbon dot-silica-phosphor (CDSP) was constructed from carbon dots (CDs), tetraethoxysilane (TEOS) and Sr2Si5N8:Eu2+ phosphor through a one-pot sol-gel method. Blue emitting CDs uniformly disperse in the silica layer covering the orange emitting phosphor via a polymerization process, which makes CDSP achieve even white light emission. Tunable photoluminescence of CDSP is observed and the preferable white light emission is achieved through changing the excitation wavelength or controlling the mass ratio of the phosphor. When CDSP powders with a phosphor rate of 3.9% and 5.1% are excited at a wavelength of 400 nm, preferable white light emission is observed, with Commission Internationale de l'Eclairage (CIE) coordinates of (0.32, 0.32) and (0.34, 0.32), respectively. Furthermore, CDSP can mix well with epoxy resin to emit strong and even white light, and based on this, a CDSP-based white LED with a high colour rendering index (CRI) of 94 was fabricated.A unique dual-emitting core-shell carbon dot-silica-phosphor (CDSP) was constructed from carbon dots (CDs), tetraethoxysilane (TEOS) and Sr2Si5N8:Eu2+ phosphor through a one-pot sol-gel method. Blue emitting CDs uniformly disperse in the silica layer covering the orange emitting phosphor via a polymerization process, which makes CDSP achieve even white light emission. Tunable photoluminescence of CDSP is observed and the preferable white light emission is achieved through changing the excitation wavelength or controlling the mass ratio of the phosphor. When CDSP powders with a phosphor rate of 3.9% and 5.1% are excited at a wavelength of 400 nm, preferable white light emission is observed, with Commission Internationale de l'Eclairage (CIE) coordinates of (0.32, 0.32) and (0.34, 0.32), respectively. Furthermore, CDSP can mix well with epoxy resin to emit strong and even white light, and based on this, a CDSP-based white LED with a high colour rendering index (CRI) of 94 was fabricated

  15. Accurate age scale of the Dome Fuji ice core, Antarctica from O2/N2 ratio of trapped air

    NASA Astrophysics Data System (ADS)

    Kawamura, K.; Aoki, S.; Nakazawa, T.; Suzuki, K.; Parrenin, F.

    2012-04-01

    Chronology of the first Dome Fuji deep ice core (core length: 2,500 m, ice thickness: 3,035 m) for the age range from 80 kyr to 340 kyr ago was established by orbital tuning of measured O2/N2 ratios in trapped air to local summer insolation, with precision better than about 2,000 years (Kawamura et al., 2007). The O2/N2 ratios found in polar ice cores are slightly lower than the atmospheric ratio because of size-dependent molecular fractionation during bubble close-off. The magnitude of this gas fractionation is believed to be governed by the magnitude of snow metamorphism when the layer was originally at the surface, which in turn is controlled by local summer insolation (Fujita et al., 2009). A strong advantage of the O2/N2 chronology is that there is no need to assume a lag between climatic records in the ice core and orbital forcings, becacuse O2/N2 ratios record local insolation through physical processes. Accuracy of the chronology was validated by comparing the O2/N2 chronology with U-Th radiometric chronology of speleothem records (Cheng et al., 2009) for the ends of Terminations II, III and IV, as well as several large climatic events, for which both ice-core CH4 and speleothem δ18O (a proxy for precipitation) show abrupt shifts as seen in the last glacial period. All ages from O2/N2 and U-Th chronology agreed with each other within ~2,000 yr. The O2/N2 chronology permits comparisons between Antarctic climate, greenhouse gases, astronomically calculated orbital parameters, and radiometrically-dated sea level and monsoon records. Here, we completed the measurements of O2/N2 ratios of the second Dome Fuji ice core, which reached bedrock, for the range from 2,400 to 3,028 m (320 - 700 kyr ago) at approximately 2,000-year time resolution. We made significant improvements in ice core storage practices and mass spectrometry. In particular, the ice core samples were stored at about -50 ° C until the air extraction, except during short periods of transportation

  16. A Centrifuge-Based Technique for Dry Extraction of Air for Ice Core Studies of Carbon Dioxide.

    NASA Astrophysics Data System (ADS)

    Grachev, A. M.; Brook, E. J.

    2008-12-01

    High resolution CO2 data from the Law Dome ice core document an abrupt ~10 ppm drop in CO2 at about 1600 AD (MacFarling Meure et al., Geophys. Res Lett., v. 33, L14810), which has been attributed to changes in human activities. CO2 measurements in ice cores are difficult, however, making verification of this feature an important task. We are undertaking a high-resolution study of CO2 between 1400 and 1800 AD in the WAIS Divide (Antarctica) ice core with a new dry extraction technique. The need for a dry extraction technique as opposed to a melt-refreeze technique in studies of CO2 from ice cores arises because of the well-documented artifacts in CO2 imposed by the presence of liquid water. Three dry-extraction methods have been employed by previous workers to measure CO2: needle-crushing method, ball-bearings method, and cheese-grater method (B. Stauffer, in: Encyclopedia of Quaternary Science, p. 1181, Elsevier 2007). Each has limitations, and we propose a simpler dry extraction technique, based on a large-capacity refrigerated centrifuge (the "centrifuge technique"), which eliminates the need to employ cryogenic temperatures to collect extracted gas and is more compatible with high sample throughput. The technique is now being tested on ~25-gram WAIS Divide samples in conjunction with CO2 measurements with a gas chromatograph. The technique employs a Beckman J- 6B centrifuge, in which evacuated stainless steel flask is placed: the flask has a weight inside positioned directly over a tall-standing piece of ice whose cross-section is small compared to that of the flask. Upon acceleration to 3000 rpm the weight moves down and presses the ice sample into a thin tablet covering flask's bottom, yielding the air extraction efficiency of ~80%. Preliminary tests suggest that precision and accuracy can be achieved at the level of ~1 ppm once the system is fine-tuned.

  17. Group velocity dispersion of CdSSe/ZnS core-shell colloidal quantum dots measured with white light interferometry

    NASA Astrophysics Data System (ADS)

    VanEngen Spivey, Amelia G.

    2016-03-01

    We measure the group velocity dispersion coefficient of CdSSe/ZnS core-shell colloidal quantum dots in liquid suspension in the ∼700-900 nm wavelength range using a white-light Michelson interferometer. Two different sizes of dots are investigated. In both cases, the group velocity dispersion coefficient decreases with increasing wavelength above the absorption edge in the dots. For quantum dots in which the linear absorption spectrum shows clear peaks, the absorption characteristics of the dots can be used to accurately model the wavelength-dependence of the group velocity dispersion coefficient.

  18. Glacial-interglacial dynamics of Antarctic firn columns: comparison between simulations and ice core air-δ15N measurements

    NASA Astrophysics Data System (ADS)

    Capron, E.; Landais, A.; Buiron, D.; Cauquoin, A.; Chappellaz, J.; Debret, M.; Jouzel, J.; Leuenberger, M.; Martinerie, P.; Masson-Delmotte, V.; Mulvaney, R.; Parrenin, F.; Prié, F.

    2012-12-01

    Correct estimate of the firn lock-in depth is essential for correctly linking gas and ice chronologies in ice cores studies. Here, two approaches to constrain the firn depth evolution in Antarctica are presented over the last deglaciation: output of a firn densification model and measurements of δ15N of N2 in air trapped in ice core. Since the firn densification process is largely governed by surface temperature and accumulation rate, we have investigated four ice cores drilled in coastal (Berkner Island, BI, and James Ross Island, JRI) and semi coastal (TALDICE and EPICA Dronning Maud Land, EDML) Antarctic regions. Combined with available δ15N measurements performed from the EPICA Dome C (EDC) site, the studied regions encompass a large range of surface accumulation rate and temperature conditions. While firn densification simulations are able to correctly represent most of the δ15N trends over the last deglaciation measured in the EDC, BI, TALDICE and EDML ice cores, they systematically fail to capture BI and EDML δ15N glacial levels, a mismatch previously seen for Central East Antarctic ice cores. Using empirical constraints of the EDML gas-ice depth offset during the Laschamp event (~ 41 ka), we can rule out the existence of a large convective zone as the explanation of the glacial firn model-δ15N data mismatch for this site. The good match between modelled and measured δ15N at TALDICE as well as the lack of any clear correlation between insoluble dust concentration in snow and δ15N records in the different ice cores suggest that past changes in loads of impurities are not the only main driver of glacial-interglacial changes in firn lock-in depth. We conclude that firn densification dynamics may instead be driven mostly by accumulation rate changes. The mismatch between modelled and measured δ15N may be due to inaccurate reconstruction of past accumulation rate or underestimated influence of accumulation rate in firnification models.

  19. Full Bayesian hierarchical light curve modeling of core-collapse supernova populations

    NASA Astrophysics Data System (ADS)

    Sanders, Nathan; Betancourt, Michael; Soderberg, Alicia Margarita

    2016-06-01

    While wide field surveys have yielded remarkable quantities of photometry of transient objects, including supernovae, light curves reconstructed from this data suffer from several characteristic problems. Because most transients are discovered near the detection limit, signal to noise is generally poor; because coverage is limited to the observing season, light curves are often incomplete; and because temporal sampling can be uneven across filters, these problems can be exacerbated at any one wavelength. While the prevailing approach of modeling individual light curves independently is successful at recovering inferences for the objects with the highest quality observations, it typically neglects a substantial portion of the data and can introduce systematic biases. Joint modeling of the light curves of transient populations enables direct inference on population-level characteristics as well as superior measurements for individual objects. We present a new hierarchical Bayesian model for supernova light curves, where information inferred from observations of every individual light curve in a sample is partially pooled across objects to constrain population-level hyperparameters. Using an efficient Hamiltonian Monte Carlo sampling technique, the model posterior can be explored to enable marginalization over weakly-identified hyperparameters through full Bayesian inference. We demonstrate our technique on the Pan-STARRS1 (PS1) Type IIP supernova light curve sample published by Sanders et al. (2015), consisting of nearly 20,000 individual photometric observations of more than 70 supernovae in five photometric filters. We discuss the Stan probabilistic programming language used to implement the model, computational challenges, and prospects for future work including generalization to multiple supernova types. We also discuss scientific results from the PS1 dataset including a new relation between the peak magnitude and decline rate of SNe IIP, a new perspective on the

  20. Performance limitation and the role of core temperature when wearing light-weight workwear under moderate thermal conditions.

    PubMed

    Kofler, Philipp; Burtscher, Martin; Heinrich, Dieter; Bottoni, Giuliamarta; Caven, Barnaby; Bechtold, Thomas; Teresa Herten, Anne; Hasler, Michael; Faulhaber, Martin; Nachbauer, Werner

    2015-01-01

    The objective of this investigation was to achieve an understanding about the relationship between heat stress and performance limitation when wearing a two-layerfire-resistant light-weight workwear (full-clothed ensemble) compared to an one-layer short sports gear (semi-clothed ensemble) in an exhaustive, stressful situation under moderate thermal condition (25°C). Ten well trained male subjects performed a strenuous walking protocol with both clothing ensembles until exhaustion occurred in a climatic chamber. Wearing workwear reduced the endurance performance by 10% (p=0.007) and the evaporation by 21% (p=0.003), caused a more pronounced rise in core temperature during submaximal walking (0.7±0.3 vs. 1.2±0.4°C; p≤0.001) and from start till exhaustion (1.4±0.3 vs. 1.8±0.5°C; p=0.008), accelerated sweat loss (13±2 vs. 15±3gmin(-1); p=0.007), and led to a significant higher heart rate at the end of cool down (103±6 vs. 111±7bpm; p=0.004). Correlation analysis revealed that core temperature development during submaximal walking and evaporation may play important roles for endurance performance. However, a critical core temperature of 40°C, which is stated to be a crucial factor for central fatigue and performance limitation, was not reached either with the semi-clothed or the full-clothed ensemble (38.3±0.4 vs. 38.4±0.5°C). Additionally, perceived exertion did not increase to a higher extent parallel with the rising core temperature with workwear which would substantiate the critical core temperature theory. In conclusion, increased heat stress led to cardiovascular exercise limitation rather than central fatigue. PMID:25526658

  1. Glycol methacrylate embedding for light microscopy. I. enzyme histochemistry on semithin sections of undecalcified marrow cores.

    PubMed

    Islam, A; Henderson, E S

    1987-10-01

    A simple, routine procedure for water miscible glycol methacrylate (GMA) embedding of undecalcified bone marrow cores, which preserves the activity of enzymes useful in diagnosing various haematopoietic disorders, is described. The GMA used in this study has a low acid content that eliminates background staining, and the modified May-Grünwald-Giemsa stain provides good definition and excellent colour differentiation of various haematopoietic cells in the bone marrow, thereby providing optimal conditions for the study of the morphology and enzyme activity of bone marrow cells in the same preparation. The method is simple, reproducible, requires no expensive equipment, and is suitable for routine processing of small bone marrow cores in any histopathology or haematology laboratory.

  2. Engineered core/shell quantum dots as phosphors for solid-state lighting

    SciTech Connect

    Klimov, Victor Ivanovich; Pietryga, Jeffrey Michael; McDaniel, Hunter

    2015-01-14

    Light-emitting diodes (LEDs) for solid state light ing (SSL) typically combine a blue or near- ultraviolet drive LED with one or more dow nconverting phosphors to produce “white” light. Further advances in both efficiency and wh ite-light quality will re quire new phosphors with narrow-band, highly efficient emission, particul arly in the red. A team led by principal investigator Dr. Victor Klim ov of Los Alamos National Labo ratory proposes to develop engineered semiconductor nanocrystal quantum dots (QDs) that combine optimal luminescent properties with long-term stability under ty pical downconverting conditions to enable new performance levels in SSL. The white LED phosphor industry is estimated to have sales of roughly $400 million in 2018 and would significantly benefit from the development of bright and narrow red-emitting QD phosphors because they woul d enable warmer whites without wasting energy by emission of light beyond the response of the human eye. In order to capitalize on the market opportunity, the LANL team is partnering with a local company called UbiQD that will facilitate US manufacturing.

  3. Some Aspects of an Air-Core Single-Coil Magnetic Suspension System

    NASA Technical Reports Server (NTRS)

    Hamlet, Irvin L.; Kilgore, Robert A.

    1966-01-01

    This paper presents some of the technical aspects in the development at the Langley Research Center of an air-cove, dual-wound, single-coil, magnetic-suspension system with one-dimensional control. Overall electrical system design features and techniques are discussed in addition to the problems of control and stability. Special treatment is given to the operation of a dual-wound, high-current support coil which provides the bias fields and superimposed modulated field. Other designs features include a six-phase, solid-state power stage for modulation of the relatively large magnitude control current, and an associated six-phase trigger circuit.

  4. A dual-emitting core-shell carbon dot-silica-phosphor composite for white light emission.

    PubMed

    Chen, Yonghao; Lei, Bingfu; Zheng, Mingtao; Zhang, Haoran; Zhuang, Jianle; Liu, Yingliang

    2015-12-21

    A unique dual-emitting core-shell carbon dot-silica-phosphor (CDSP) was constructed from carbon dots (CDs), tetraethoxysilane (TEOS) and Sr2Si5N8:Eu(2+) phosphor through a one-pot sol-gel method. Blue emitting CDs uniformly disperse in the silica layer covering the orange emitting phosphor via a polymerization process, which makes CDSP achieve even white light emission. Tunable photoluminescence of CDSP is observed and the preferable white light emission is achieved through changing the excitation wavelength or controlling the mass ratio of the phosphor. When CDSP powders with a phosphor rate of 3.9% and 5.1% are excited at a wavelength of 400 nm, preferable white light emission is observed, with Commission Internationale de l'Eclairage (CIE) coordinates of (0.32, 0.32) and (0.34, 0.32), respectively. Furthermore, CDSP can mix well with epoxy resin to emit strong and even white light, and based on this, a CDSP-based white LED with a high colour rendering index (CRI) of 94 was fabricated. PMID:26573998

  5. Multicolor Light Curve Simulations of Population III Core-Collapse Supernovae: From Shock Breakout to 56Co Decay

    NASA Astrophysics Data System (ADS)

    Tolstov, Alexey; Nomoto, Ken'ichi; Tominaga, Nozomu; Ishigaki, Miho N.; Blinnikov, Sergey; Suzuki, Tomoharu

    2016-04-01

    The properties of the first generation of stars and their supernova (SN) explosions remain unknown due to the lack of actual observations. Recently, many transient surveys have been conducted and the feasibility of detecting supernovae (SNe) of Pop III stars is growing. In this paper, we study the multicolor light curves for a number of metal-free core-collapse SN models (25-100 {M}⊙ ) to determine the indicators for the detection and identification of first generation SNe. We use mixing-fallback supernova explosion models that explain the observed abundance patterns of metal-poor stars. Numerical calculations of the multicolor light curves are performed using the multigroup radiation hydrodynamic code stella. The calculated light curves of metal-free SNe are compared with non-zero-metallicity models and several observed SNe. We have found that the shock breakout characteristics, the evolution of the photosphere’s velocity, the luminosity, and the duration and color evolution of the plateau, that is, all of the SN phases from shock breakout to 56Co decay, are helpful for estimating the parameters of the SN progenitor: the mass, the radius, the explosion energy, and the metallicity. We conclude that the multicolor light curves could potentially be used to identify first-generation SNe in current (Subaru/HSC) and future transient surveys (LSST, James Webb Space Telescope). They are also suitable for identifying low-metallicity SNe in the nearby universe (PTF, Pan-STARRS, Gaia).

  6. A new equation of state with light nuclei and their weak interactions in core-collapse supernova simulations

    SciTech Connect

    Furusawa, Shun; Yamada, Shoichi; Nagakura, Hiroki; Sumiyoshi, Kohsuke; Suzuki, Hideyuki

    2014-05-02

    We perform numerical experiments to investigate the influence of inelastic neutrino reactions with light nuclei on the standing accretion shock instability. The time evolutions of shock waves are calculated with a simple light-bulb approximation for the neutrino transport and a multi-nuclei equation of state. The neutrino absorptions and inelastic interactions with deuterons, tritons, helions and alpha particles are taken into account in the hydrodynamical simulations in addition to the ordinary charged-current interactions with nucleons. Axial symmetry is assumed but no equatorial symmetry is imposed. We show that the heating rates of deuterons reach as high as ∼ 10% of those of nucleons around the bottom of the gain region. On the other hands, alpha particles heat the matter near the shock wave, which is important when the shock wave expands and density and temperature of matter become low. It is also found that the models with heating by light nuclei have different evolutions from those without it in non-linear evolution phase. The matter in the gain region has various densities and temperatures and there appear regions that are locally rich in deuterons and alpha particles. These results indicate that the inelastic reactions of light nuclei, especially deuterons, should be incorporated in the simulations of core-collapse supernovae.

  7. A new equation of state with light nuclei and their weak interactions in core-collapse supernova simulations

    NASA Astrophysics Data System (ADS)

    Furusawa, Shun; Nagakura, Hiroki; Sumiyoshi, Kohsuke; Yamada, Shoichi; Suzuki, Hideyuki

    2014-05-01

    We perform numerical experiments to investigate the influence of inelastic neutrino reactions with light nuclei on the standing accretion shock instability. The time evolutions of shock waves are calculated with a simple light-bulb approximation for the neutrino transport and a multi-nuclei equation of state. The neutrino absorptions and inelastic interactions with deuterons, tritons, helions and alpha particles are taken into account in the hydrodynamical simulations in addition to the ordinary charged-current interactions with nucleons. Axial symmetry is assumed but no equatorial symmetry is imposed. We show that the heating rates of deuterons reach as high as ˜ 10% of those of nucleons around the bottom of the gain region. On the other hands, alpha particles heat the matter near the shock wave, which is important when the shock wave expands and density and temperature of matter become low. It is also found that the models with heating by light nuclei have different evolutions from those without it in non-linear evolution phase. The matter in the gain region has various densities and temperatures and there appear regions that are locally rich in deuterons and alpha particles. These results indicate that the inelastic reactions of light nuclei, especially deuterons, should be incorporated in the simulations of core-collapse supernovae.

  8. Ab initio no core calculations of light nuclei and preludes to Hamiltonian quantum field theory

    SciTech Connect

    Vary, J.P.; Maris, P.; Shirokov, A.M.; Honkanen, H.; li, J.; Brodsky, S.J.; Harindranath, A.; Teramond, G.F.de; /Costa Rica U.

    2009-08-03

    Recent advances in ab initio quantum many-body methods and growth in computer power now enable highly precise calculations of nuclear structure. The precision has attained a level sufficient to make clear statements on the nature of 3-body forces in nuclear physics. Total binding energies, spin-dependent structure effects, and electroweak properties of light nuclei play major roles in pinpointing properties of the underlying strong interaction. Eventually,we anticipate a theory bridge with immense predictive power from QCD through nuclear forces to nuclear structure and nuclear reactions. Light front Hamiltonian quantum field theory offers an attractive pathway and we outline key elements.

  9. Nanoscale semiconductor-insulator-metal core/shell heterostructures: facile synthesis and light emission

    NASA Astrophysics Data System (ADS)

    Li, Gong Ping; Chen, Rui; Guo, Dong Lai; Wong, Lai Mun; Wang, Shi Jie; Sun, Han Dong; Wu, Tom

    2011-08-01

    Controllably constructing hierarchical nanostructures with distinct components and designed architectures is an important theme of research in nanoscience, entailing novel but reliable approaches of bottom-up synthesis. Here, we report a facile method to reproducibly create semiconductor-insulator-metal core/shell nanostructures, which involves first coating uniform MgO shells onto metal oxide nanostructures in solution and then decorating them with Au nanoparticles. The semiconductor nanowire core can be almost any material and, herein, ZnO, SnO2 and In2O3 are used as examples. We also show that linear chains of short ZnO nanorods embedded in MgO nanotubes and porous MgO nanotubes can be obtained by taking advantage of the reduced thermal stability of the ZnO core. Furthermore, after MgO shell-coating and the appropriate annealing treatment, the intensity of the ZnO near-band-edge UV emission becomes much stronger, showing a 25-fold enhancement. The intensity ratio of the UV/visible emission can be increased further by decorating the surface of the ZnO/MgO nanowires with high-density plasmonic Au nanoparticles. These heterostructured semiconductor-insulator-metal nanowires with tailored morphologies and enhanced functionalities have great potential for use as nanoscale building blocks in photonic and electronic applications.Controllably constructing hierarchical nanostructures with distinct components and designed architectures is an important theme of research in nanoscience, entailing novel but reliable approaches of bottom-up synthesis. Here, we report a facile method to reproducibly create semiconductor-insulator-metal core/shell nanostructures, which involves first coating uniform MgO shells onto metal oxide nanostructures in solution and then decorating them with Au nanoparticles. The semiconductor nanowire core can be almost any material and, herein, ZnO, SnO2 and In2O3 are used as examples. We also show that linear chains of short ZnO nanorods embedded in

  10. Civil air transport: A fresh look at power-by-wire and fly-by-light

    NASA Technical Reports Server (NTRS)

    Sundberg, Gale R.

    1990-01-01

    Power-by-wire (PBW) is a key element under subsonic transport flight systems technology with potential savings of over 10 percent in gross take-off-weight and in fuel consumption compared to today's transport aircraft. The PBW technology substitutes electrical actuation in place of centralized hydraulics, uses internal starter-motor/generators and eliminates the need for variable engine bleed air to supply cabin comfort. The application of advanced fiber optics to the electrical power system controls, to built-in-test (BITE) equipment, and to fly-by-light (FBL) flight controls provides additional benefits in lightning and high energy radio frequency (HERF) immunity over existing mechanical or even fly-by-wire controls. The program plan is reviewed and a snapshot is given of the key technologies and their benefits to all future aircraft, both civil and military.

  11. Civil air transport: A fresh look at power-by-wire and fly-by-light

    NASA Technical Reports Server (NTRS)

    Sundberg, Gale R.

    1991-01-01

    Power-by-wire (PBW) is a key element under subsonic transport flight systems technology with potential savings of over 10 percent in operating empty weight and in fuel consumption compared to today's transport aircraft. The PBW technology substitutes electrical actuation in place of centralized hydraulics, uses internal starter-motor/generators and eliminates the need for variable engine bleed air to supply cabin comfort. The application of advanced fiber optics to the electrical power system controls, to built-in-test (BIT) equipment, and to fly-by-light (FBL) flight controls provides additional benefits in lightning and high energy radio frequency (HERF) immunity over existing mechanical or even fly-by-wire controls. The program plan is reviewed and a snapshot is given of the key technologies and their benefits to all future aircraft, both civil and military.

  12. Civil air transport: A fresh look at power-by-wire and fly-by-light

    NASA Astrophysics Data System (ADS)

    Sundberg, Gale R.

    1990-05-01

    Power-by-wire (PBW) is a key element under subsonic transport flight systems technology with potential savings of over 10 percent in gross take-off-weight and in fuel consumption compared to today's transport aircraft. The PBW technology substitutes electrical actuation in place of centralized hydraulics, uses internal starter-motor/generators and eliminates the need for variable engine bleed air to supply cabin comfort. The application of advanced fiber optics to the electrical power system controls, to built-in-test (BITE) equipment, and to fly-by-light (FBL) flight controls provides additional benefits in lightning and high energy radio frequency (HERF) immunity over existing mechanical or even fly-by-wire controls. The program plan is reviewed and a snapshot is given of the key technologies and their benefits to all future aircraft, both civil and military.

  13. Civil air transport - A fresh look at power-by-wire and fly-by-light

    NASA Technical Reports Server (NTRS)

    Sundberg, Gale R.

    1990-01-01

    Power-by-wire (PBW) is a key element under subsonic transport flight systems technology, with potential savings of over 10 percent in gross take off weight and in fuel consumption compared to today's transport aircraft. The PBW technology substitutes electrical actuation in place of centralized hydraulics, uses internal starter-motor/generators, and eliminates the need for variable engine bleed air to supply cabin comfort. The application of advanced fiber optics to the electrical power system controls, to built-in-test (BITE) equipment, and to fly-by-light (FBL) flight controls provides additional benefits in lightning and high-energy radio frequency (HERF) immunity over existing mechanical or even fly-by-wire controls. The program plan is reviewed and a snapshot is given of the key technologies and their benefits to future aircraft, both civil and military.

  14. White light emitting diode based on InGaN chip with core/shell quantum dots

    NASA Astrophysics Data System (ADS)

    Shen, Changyu; Hong, Yan; Ma, Jiandong; Ming, Jiangzhou

    2009-08-01

    Quantum dots have many applications in optoelectronic device such as LEDs for its many superior properties resulting from the three-dimensional confinement effect of its carrier. In this paper, single chip white light-emitting diodes (WLEDs) were fabricated by combining blue InGaN chip with luminescent colloidal quantum dots (QDs). Two kinds of QDs of core/shell CdSe /ZnS and core/shell/shell CdSe /ZnS /CdS nanocrystals were synthesized by thermal deposition using cadmium oxide and selenium as precursors in a hot lauric acid and hexadecylamine trioctylphosphine oxide hybrid. This two kinds of QDs exhibited high photoluminescence efficiency with a quantum yield more than 41%, and size-tunable emission wavelengths from 500 to 620 nm. The QDs LED mainly consists of flip luminescent InGaN chip, glass ceramic protective coating, glisten cup, QDs using as the photoluminescence material, pyroceram, gold line, electric layer, dielectric layer, silicon gel and bottom layer for welding. The WLEDs had the CIE coordinates of (0.319, 0.32). The InGaN chip white-light-emitting diodes with quantum dots as the emitting layer are potentially useful in illumination and display applications.

  15. Light-weight sandwich panel honeycomb core with hybrid carbon-glass fiber composite skin for electric vehicle application

    NASA Astrophysics Data System (ADS)

    Cahyono, Sukmaji Indro; Widodo, Angit; Anwar, Miftahul; Diharjo, Kuncoro; Triyono, Teguh; Hapid, A.; Kaleg, S.

    2016-03-01

    The carbon fiber reinforced plastic (CFRP) composite is relative high cost material in current manufacturing process of electric vehicle body structure. Sandwich panels consisting polypropylene (PP) honeycomb core with hybrid carbon-glass fiber composite skin were investigated. The aim of present paper was evaluate the flexural properties and bending rigidity of various volume fraction carbon-glass fiber composite skins with the honeycomb core. The flexural properties and cost of panels were compared to the reported values of solid hybrid Carbon/Glass FRP used for the frame body structure of electric vehicle. The finite element model of represented sandwich panel was established to characterize the flexural properties of material using homogenization technique. Finally, simplified model was employed to crashworthiness analysis for engine hood of the body electric vehicle structure. The good cost-electiveness of honeycomb core with hybrid carbon-glass fiber skin has the potential to be used as a light-weight alternative material in body electric vehicle fabricated.

  16. An Optimized Air-Core Coil Sensor with a Magnetic Flux Compensation Structure Suitable to the Helicopter TEM System

    PubMed Central

    Chen, Chen; Liu, Fei; Lin, Jun; Zhu, Kaiguang; Wang, Yanzhang

    2016-01-01

    The air-core coil sensor (ACS) is widely used as a transducer to measure the variation in magnetic fields of a helicopter transient electromagnetic (TEM) system. A high periodic emitting current induces the magnetic field signal of the underground medium. However, such current also generates a high primary field signal that can affect the received signal of the ACS and even damage the receiver. To increase the dynamic range of the received signal and to protect the receiver when emitting current rises/falls, the combination of ACS with magnetic flux compensation structure (bucking coil) is necessary. Moreover, the optimized ACS, which is composed of an air-core coil and a differential pre-amplifier circuit, must be investigated to meet the requirements of the helicopter TEM system suited to rapid surveying for shallow buried metal mine in rough topography. Accordingly, two ACSs are fabricated in this study, and their performance is verified and compared inside a magnetic shielding room. Using the designed ACSs, field experiments are conducted in Baoqing County. The field experimental data show that the primary field response can be compensated when the bucking coil is placed at an appropriate point in the range of allowed shift distance beyond the center of the transmitting coil and that the damage to the receiver induced by the over-statured signal can be solved. In conclusion, a more suitable ACS is adopted and is shown to have better performance, with a mass of 2.5 kg, resultant effective area of 11.6 m2 (i.e., diameter of 0.496 m), 3 dB bandwidth of 66 kHz, signal-to-noise ratio of 4 (i.e., varying magnetic field strength of 0.2 nT/s), and normalized equivalent input noise of 3.62 nV/m2. PMID:27077862

  17. No-Core Shell Model Calculations in Light Nuclei with Three-Nucleon Forces

    SciTech Connect

    Barrett, B R; Vary, J P; Nogga, A; Navratil, P; Ormand, W E

    2004-01-08

    The ab initio No-Core Shell Model (NCSM) has recently been expanded to include nucleon-nucleon (NN) and three-nucleon (3N) interactions at the three-body cluster level. Here it is used to predict binding energies and spectra of p-shell nuclei based on realistic NN and 3N interactions. It is shown that 3N force (3NF) properties can be studied in these nuclear systems. First results show that interactions based on chiral perturbation theory lead to a realistic description of {sup 6}Li.

  18. Wind-driven influences on aerosol light scattering in north-east Atlantic air

    NASA Astrophysics Data System (ADS)

    Vaishya, Aditya; Jennings, S. Gerard; O'Dowd, Colin

    2012-03-01

    Ten years (2001-2010) of aerosol light-scattering measurements in N.E. Atlantic marine air are analysed to determine wind-speed related influences on scattering properties. The scattering coefficient and the backscattering coefficient dependency on wind speed (U) was determined for the winter (Low Biological Activity-LBA) and the summer seasons (High Biological Activity-HBA), and was found to be dependent on ˜U2. In spite of having a U2 dependency, scattering properties for the LBA-period are approximately twice those of the HBA-period. 96% of the LBA-HBA scattering difference can be explained by the combined effects of size distribution and refractive index differences while 70% of the scattering difference can be attributed to a difference in refractive index alone resulting from organic-matter enrichment during the HBA period. The 550 nm scattering coefficient was ˜70 Mm-1 for ˜25 ms-1 wind speeds, which is considerably higher than that encountered under polluted air masses in the same region.

  19. Department of Energy Office of Energy Efficiency and Renewable Energy Solid Lighting Core Technologies

    SciTech Connect

    Jiangeng Xue; Elliot Douglas

    2011-03-31

    The overall objective of this project is to demonstrate an ultra-effective light extraction mechanism that can be universally applied to all top-emitting white OLEDs (TE-WOLEDs) and can be integrated with thin film encapsulation techniques. The scope of work proposed in this project includes four major areas: (1) optical modeling; (2) microlens and array fabrication; (3) fabrication, encapsulation, and characterization of TE-WOLEDs; and (4) full device integration and characterization. First, the light extraction efficiency in a top-emitting OLED with or without a microlens array are modeled using wave optics. Second, individual microlenses and microlens arrays are fabricated by inkjet printing of microdroplets of a liquid thiol-ene monomer with high refractive index followed by photopolymerization. Third, high efficiency top-emitting white OLEDs are fabricated, and fully characterized. Finally, optimized microlens arrays are fabricated on TE-WOLEDs with dielectric barrier layers. The overall light extraction efficiency of these devices, as well as its wavelength and angular dependencies, are measured by comparing the efficiencies of devices with and without microlens arrays. In conclusion, we have demonstrated the feasibility of applying inkjet printed microlens arrays to enhance the light extraction efficiency of top-emitting white OLEDs. We have shown that the geometry (contact angle) of the printed microlenses can be controlled by controlling the surface chemistry prior to printing the lenses. A 90% enhancement in the light extraction efficiency has been achieved with printed microlens array on a top-emitting white OLED, which can be further improved to 140% using a more close-packed microlens array fabricated from a molding process. Future work will focus on improvement of the microlens fabrication process to improve the array fill factor and the contact angle, as well as use transparent materials with a higher index of refraction. We will also further

  20. Visible-light-enhanced electrocatalysis and bioelectrocatalysis coupled in a miniature glucose/air biofuel cell.

    PubMed

    Zhang, Lingling; Xu, Zhikun; Lou, Baohua; Han, Lei; Zhang, Xiaowei; Dong, Shaojun

    2014-09-01

    A glucose/air biofuel cell (BFC) that can convert both chemical and light energy into electricity is described. Polyterthiophene (pTTh), a photoresponsive conducting polymer, serves as cathode and catalyzes the reduction of oxygen. Taking advantage of the good environmental stability and exceptional optical properties of pTTh, the assembled BFC exhibits excellent stability and a fast photoresponse with an open-circuit voltage (V(oc)) of 0.50 V and a maximum power output density (P(max)) of 23.65 μW cm(-2) upon illumination by visible light of 10 mW cm(-2) , which is an enhancement of ca. 22 times as compared to P(max) in the dark. Additionally, we propose a possible mechanism for this enhancement. Fabricating a BFC in this manner provides an energy conversion model that offers high efficiency at low cost, paving an avenue for practical solar energy conversion on a large scale.

  1. A method of observing cherenkov light from extensive air shower at Yakutsk EAS array

    NASA Astrophysics Data System (ADS)

    Timofeev, Lev; Anatoly, Ivanov

    2016-07-01

    Proposed a new method for measuring the cherenkov light from the extensive air shower (EAS) of cosmic rays (CR), which allows to determine not only the primary particle energy and angle of arrival, but also the parameters of the shower in the atmosphere - the maximum depth and "age". For measurements Cherenkov light produced by EAS is proposed to use a ground network of wide-angle telescopes which are separated from each other by a distance 100-300 m depending on the total number of telescopes operating in the coincidence signals, acting autonomously, or includes a detector of the charged components, radio waves, etc. as part of EAS. In a results such array could developed, energy measurement and CR angle of arrival data on the depth of the maximum and the associated mass of the primary particle generating by EAS. This is particularly important in the study of galactic cosmic ray in E> 10^14 eV, where currently there are no direct measurements of the maximum depth of the EAS.

  2. Visible-light-enhanced electrocatalysis and bioelectrocatalysis coupled in a miniature glucose/air biofuel cell.

    PubMed

    Zhang, Lingling; Xu, Zhikun; Lou, Baohua; Han, Lei; Zhang, Xiaowei; Dong, Shaojun

    2014-09-01

    A glucose/air biofuel cell (BFC) that can convert both chemical and light energy into electricity is described. Polyterthiophene (pTTh), a photoresponsive conducting polymer, serves as cathode and catalyzes the reduction of oxygen. Taking advantage of the good environmental stability and exceptional optical properties of pTTh, the assembled BFC exhibits excellent stability and a fast photoresponse with an open-circuit voltage (V(oc)) of 0.50 V and a maximum power output density (P(max)) of 23.65 μW cm(-2) upon illumination by visible light of 10 mW cm(-2) , which is an enhancement of ca. 22 times as compared to P(max) in the dark. Additionally, we propose a possible mechanism for this enhancement. Fabricating a BFC in this manner provides an energy conversion model that offers high efficiency at low cost, paving an avenue for practical solar energy conversion on a large scale. PMID:24961677

  3. Near-Infrared Light-Responsive Core-Shell Nanogels for Targeted Drug Delivery

    PubMed Central

    Kang, Huaizhi; Trondoli, Anna Carolina; Zhu, Guizhi; Chen, Yan; Chang, Ya-Jen; Liu, Haipeng; Huang, Yu-Fen; Zhang, Xiaoling; Tan, Weihong

    2011-01-01

    A near-infrared light-responsive drug delivery platform based on Au-Ag-nanorods (Au-Ag NRs) coated with DNA-crosslinked polymeric shells was constructed. DNA complementarity has been applied to develop a polyacrylamide-based sol-gel transition system to encapsulate anticancer drugs into the gel scaffold. The Au-Ag NR based nanogels can also be readily functionalized with targeting moieties, such as aptamers, for specific recognition of tumor cells. When exposed to NIR irradiation, the photothermal effect of the Au-Ag NRs leads to a rapid rise in the temperature of the surrounding gel, resulting in the fast release of the encapsulated payload with high controllability. In vitro study confirmed that aptamer functionalized nanogels can be used as drug carriers feasible for targeted drug delivery with remote control capability by NIR light with high spatial/temporal resolution. PMID:21542633

  4. Near-infrared light-responsive core-shell nanogels for targeted drug delivery.

    PubMed

    Kang, Huaizhi; Trondoli, Anna Carolina; Zhu, Guizhi; Chen, Yan; Chang, Ya-Jen; Liu, Haipeng; Huang, Yu-Fen; Zhang, Xiaoling; Tan, Weihong

    2011-06-28

    A near-infrared light-responsive drug delivery platform based on Au-Ag nanorods (Au-Ag NRs) coated with DNA cross-linked polymeric shells was constructed. DNA complementarity has been applied to develop a polyacrylamide-based sol-gel transition system to encapsulate anticancer drugs into the gel scaffold. The Au-Ag NR-based nanogels can also be readily functionalized with targeting moieties, such as aptamers, for specific recognition of tumor cells. When exposed to NIR irradiation, the photothermal effect of the Au-Ag NRs leads to a rapid rise in the temperature of the surrounding gel, resulting in the fast release of the encapsulated payload with high controllability. In vitro study confirmed that aptamer-functionalized nanogels can be used as drug carriers for targeted drug delivery with remote control capability by NIR light with high spatial/temporal resolution.

  5. Near-infrared light-responsive core-shell nanogels for targeted drug delivery.

    PubMed

    Kang, Huaizhi; Trondoli, Anna Carolina; Zhu, Guizhi; Chen, Yan; Chang, Ya-Jen; Liu, Haipeng; Huang, Yu-Fen; Zhang, Xiaoling; Tan, Weihong

    2011-06-28

    A near-infrared light-responsive drug delivery platform based on Au-Ag nanorods (Au-Ag NRs) coated with DNA cross-linked polymeric shells was constructed. DNA complementarity has been applied to develop a polyacrylamide-based sol-gel transition system to encapsulate anticancer drugs into the gel scaffold. The Au-Ag NR-based nanogels can also be readily functionalized with targeting moieties, such as aptamers, for specific recognition of tumor cells. When exposed to NIR irradiation, the photothermal effect of the Au-Ag NRs leads to a rapid rise in the temperature of the surrounding gel, resulting in the fast release of the encapsulated payload with high controllability. In vitro study confirmed that aptamer-functionalized nanogels can be used as drug carriers for targeted drug delivery with remote control capability by NIR light with high spatial/temporal resolution. PMID:21542633

  6. Visible Light Responsive Catalysts Using Quantum Dot-Modified Ti02 for Air and Water Purification

    NASA Technical Reports Server (NTRS)

    Coutts, Janelle L.; Levine, Lanfang H.; Richards, Jeffrey T.; Hintze, paul; Clausen, Christian

    2012-01-01

    The method of photocatalysis utilizing titanium dioxide, TiO2, as the catalyst has been widely studied for trace contaminant control for both air and water applications because of its low energy consumption and use of a regenerable catalyst. Titanium dioxide requires ultraviolet light for activation due to its band gap energy of 3.2 eV. Traditionally, Hg-vapor fluorescent light sources are used in PCO reactors and are a setback for the technology for space application due to the possibility of Hg contamination. The development of a visible light responsive (VLR) TiO2-based catalyst could lead to the use of solar energy in the visible region (approx.45% of the solar spectrum lies in the visible region; > 400 nm) or highly efficient LEDs (with wavelengths > 400 nm) to make PCO approaches more efficient, economical, and safe. Though VLR catalyst development has been an active area of research for the past two decades, there are few commercially available VLR catalysts; those that are available still have poor activity in the visible region compared to that in the UV region. Thus, this study was aimed at the further development of VLR catalysts by a new method - coupling of quantum dots (QD) of a narrow band gap semiconductor (e.g., CdS, CdSe, PbS, ZnSe, etc.) to the TiO2 by two preparation methods: 1) photodeposition and 2) mechanical alloying using a high-speed ball mill. A library of catalysts was developed and screened for gas and aqueous phase applications, using ethanol and 4-chlorophenol as the target contaminants, respectively. Both target compounds are well studied in photocatalytic systems serve as model contaminants for this research. Synthesized catalysts were compared in terms of preparation method, type of quantum dots, and dosage of quantum dots.

  7. First detection of Cherenkov light from cosmic-particle-induced air showers by Geiger-mode avalanche photodiodes

    NASA Astrophysics Data System (ADS)

    Biland, A.; Britvitch, I.; Lorenz, E.; Otte, N.; Pauss, F.; Renker, D.; Ritt, S.; Roeser, U.; Schneebeli, M.

    2007-10-01

    We report on first tests of Geiger-mode APDs (G-APD) to detect Cherenkov light from cosmic particle induced air showers. The motivation for this study stems from the requirement to improve the sensitivity of large imaging atmospheric Cherenkov telescopes (IACT) by replacing the photomultipliers (PMT) by high detection efficiency G-APDs. Three tests have been carried out, confirming sufficiently high light sensitivity of blue-sensitive G-APDs as future replacement of PMTs in IACTs.

  8. Degradation of organic dyes by Si/SiOx core-shell nanowires: Spontaneous generation of superoxides without light irradiation.

    PubMed

    Cao, Yu; Gu, Xiaoyu; Yu, Hongkun; Zeng, Wei; Liu, Xiang; Jiang, Suhua; Li, Yuesheng

    2016-02-01

    Recently, silicon nanowires (SiNWs) have been proven to be highly active in the photocatalysis of dye degradation. However, the unstable hydrogen-terminated surface and the need for constant light irradiation hinder their extensive use. In this work, a stable silica shell was intentionally formed on the surface of SiNWs to produce Si/SiOx core-shell silicon nanowires (S-SiNWs). Light-illuminated or not, S-SiNWs showed almost identical degradation ability for the degradation of indigo carmine (IC) in both conditions, which meant neither hydrogen termination nor light irradiation was a prerequisite for the degradation activity of S-SiNWs. UV/Vis spectroscopy and liquid chromatography/mass spectrometry showed that IC was converted into isatin sulfonic acid in this process. Quenching studies and electron paramagnetic resonance spectroscopy revealed that this bleaching ability was highly dependent on superoxides. A possible mechanism was accordingly suggested. In addition, the recently discovered reductase-like activity of SiNWs can be explained by the superoxides generation.

  9. Experiments and theoretical modelling for a core catcher concept for future light water reactors

    SciTech Connect

    Tromm, W.; Alsmeyer, H.; Buerger, M.; Widmann, W.; Buck, M.

    1996-12-31

    The COMET concept of corium cooling is proposed to be integrated into future reactors. The concept is based on spreading of the ex-vessel core-melt on a sacrificial concrete layer and, after erosion of this layer, flooding the melt by totally passive water ingression from below through a multitude of melt plugs. The resulting evaporation and interaction processes should lead to a fragmented and porously solidified melt, rapidly coolable through open flow channels. The important processes of melt fragmentation and heat transfer from the melt at direct water contact are investigated with thermite melts in medium scale experiments, and with decay heat simulation in large scale experiments in the modified BETA facility. The experiments show fast cool-down of the melt and solidification of the metallic and oxidic fraction of the melt as a porous structure which, due to its high permeability for the steam-water flow, ensures short-term and long-term coolability. As the experiments are 1-dimensional representations of the central section of the core catcher in the characteristic scale, they should be directly applicable to reactor conditions. Specific tests on the possibility of steam explosions at the initial melt water contact showed very low mechanical loads. The conceptual and experimental work at FZK is accompanied by theoretical investigations at IKE, Stuttgart. Main aims are to optimize the cooling behavior and to evaluate the possible threat by strong steam explosions. Penetration of water jets into an overlying melt layer and resulting phenomena of fragmentation, coolant channel and porous medium formation constitute the key physical processes. Basic models have been developed and applied to the experiments.

  10. Microfabrication of air core power inductors with metal-encapsulated polymer vias

    SciTech Connect

    Kim, J; Herrault, F; Yu, XH; Kim, M; Shafer, RH; Allen, MG

    2013-01-25

    This paper reports three-dimensional (3-D) microfabricated toroidal inductors intended for power electronics applications. A key fabrication advance is the exploitation of thick metal encapsulation of polymer pillars to form a vertical via interconnections. The radial conductors of the toroidal inductor are formed by conventional plating-through-mold techniques, while the vertical windings (up to 650 mu m in height) are formed by polymer cores with metal plated on their external surfaces. This encapsulated polymer approach not only significantly reduces the required plating time but also exploits the relative ease of fabricating high-aspect-ratio SU-8 pillars. To form the top radial conductors, non-photopatternable SU-8 is introduced as a thick sacrificial layer. Two toroidal inductor geometries were fabricated and tested. The first inductor had an inner diameter of 2 mm, an outer diameter of 6 mm, 25 turns and a vertical via height of 650 mu m. The second inductor had an inner diameter of 4 mm, an outer diameter of 8 mm, 50 turns and a vertical via height of 650 mu m. Both inductor geometries were successfully fabricated and characterized in the frequency range of 0.1-100 MHz. Characterization results of the 25- and 50-turn inductors showed an average inductance of 76 and 200 nH, a low frequency (0.1 MHz) resistance of 0.2 and 1 Omega and a quality factor of 35 and 24 at 100 MHz, respectively. Finite-element simulations of the inductors were performed and agreed with the measured results to within 8%. The turn-to-turn breakdown voltage was measured to be in excess of 800 V and currents as high as 0.5 A could be successfully carried by the inductor windings.

  11. Department of Energy Office of Energy Efficiency and Renewable Energy Solid State Lighting Core Technologies

    SciTech Connect

    Franky So; Paul Holloway; Jiangeng Xue

    2009-08-06

    The project objective is to demonstrate high efficiency white emitting OLED devices with a target luminous efficiency between 100 1m/W and 150 1m/W with integrated microcavity structure and down conversion phosphors. The main focus of this work will be on three areas: (1) demonstration of a 2X reduction in OLED device operating voltage by employing the appropriate dopants in the carrier transporting layers; (2) demonstration of a 3X light out-coupling efficiency enhancement by incorporating microcavity structure in the OLED devices; and (3) demonstration of a 2X down-conversion efficiency enhancement (from blue to white) using phosphors.

  12. A preliminary investigation into the use of Red Pine (Pinus Resinosa) tree cores as historic passive samplers of POPs in outdoor air

    NASA Astrophysics Data System (ADS)

    Rauert, Cassandra; Harner, Tom

    2016-09-01

    The suitability of Red Pine trees (Pinus Resinosa) to act as passive samplers for persistent organic pollutants (POPs) in outdoor air and to provide historic information on air concentration trends was demonstrated in this preliminary investigation. Red Pine tree cores from Toronto, Canada, were tested for polycyclic aromatic hydrocarbon (PAHs), alkylated-PAHs, nitro and oxy-PAHs, polybrominated diphenyl ethers (PBDEs) and novel brominated flame retardants (novel BFRs). The PBDEs and novel BFRs demonstrated a similar relative contribution in cores representing 30 years of tree growth, to that reported in contemporary air samples. Analysis of tree ring segments of 5-15 years resulted in detectable concentrations of some PAHs and alk-PAHs and demonstrated a transition from petrogenic sources to pyrogenic sources over the period 1960-2015. A simple uptake model was developed that treats the tree rings as linear-phase passive air samplers. The bark infiltration factor, IFBARK, is a key parameter of the model that reflects the permeability of the bark to allow chemicals to be transferred from ambient air to the outer tree layer (cambium). An IFBARK of about 2% was derived for the Red Pine trees based on tree core and air monitoring data.

  13. Visible-Light Responsive Catalysts Using Quantum Dot-Modified TiO2 for Air and Water Purification

    NASA Technical Reports Server (NTRS)

    Coutts, Janelle L.; Hintze, Paul E.; Clausen, Christian A.; Richards, Jeffrey T.

    2014-01-01

    Photocatalysis, the oxidation or reduction of contaminants by light-activated catalysts, utilizing titanium dioxide (TiO2) as the catalytic substrate has been widely studied for trace contaminant control in both air and water applications. The interest in this process is due primarily to its low energy consumption and capacity for catalyst regeneration. Titanium dioxide requires ultraviolet light for activation due to its relatively large band gap energy of 3.2 eV. Traditionally, Hg-vapor fluorescent light sources are used in PCO reactors; however, the use of mercury precludes the use of this PCO technology in a spaceflight environment due to concerns over crew Hg exposure.

  14. Protective structures on the surface of zirconium components of light water reactor cores: Formation, testing, and prototype equipment

    SciTech Connect

    Begrambekov, L. B.; Gordeev, A. A.; Evsin, A. E. Ivanova, S. V.; Kaplevsky, A. S.; Sadovskiy, Ya. A.

    2015-12-15

    The results of tests of plasma treatment of zirconium and deposition of protective yttrium coatings used as the methods of protection of zirconium components of light water reactor cores against hydrogenation are detailed. The amount of hydrogen in the treated sample exposed to superheated steam for 2500 h at temperature T = 400°C and pressure p = 1 atm was five times lower than the corresponding value for the untreated one. The amount of hydrogen in the sample coated with yttrium remained almost unchanged in 4000 h of exposure. A plasma method for rapid testing for hydrogen resistance is proposed. The hydrogenation rate provided by this method is 700 times higher than that in tests with superheated steam. The results of preliminary experiments confirm the possibility of constructing a unit for batch processing of the surfaces of fuel rod claddings.

  15. Two-photon excitation cross section in light and intermediate atoms in frozen-core LS-coupling approximation

    NASA Technical Reports Server (NTRS)

    Omidvar, K.

    1980-01-01

    Using the method of explicit summation over the intermediate states two-photon absorption cross sections in light and intermediate atoms based on the simplistic frozen-core approximation and LS coupling have been formulated. Formulas for the cross section in terms of integrals over radial wave functions are given. Two selection rules, one exact and one approximate, valid within the stated approximations are derived. The formulas are applied to two-photon absorptions in nitrogen, oxygen, and chlorine. In evaluating the radial integrals, for low-lying levels, the Hartree-Fock wave functions, and for high-lying levels, hydrogenic wave functions obtained by the quantum-defect method have been used. A relationship between the cross section and the oscillator strengths is derived.

  16. Light absorption processes and optimization of ZnO/CdTe core-shell nanowire arrays for nanostructured solar cells.

    PubMed

    Michallon, Jérôme; Bucci, Davide; Morand, Alain; Zanuccoli, Mauro; Consonni, Vincent; Kaminski-Cachopo, Anne

    2015-02-20

    The absorption processes of extremely thin absorber solar cells based on ZnO/CdTe core-shell nanowire (NW) arrays with square, hexagonal or triangular arrangements are investigated through systematic computations of the ideal short-circuit current density using three-dimensional rigorous coupled wave analysis. The geometrical dimensions are optimized for optically designing these solar cells: the optimal NW diameter, height and array period are of 200 ± 10 nm, 1-3 μm and 350-400 nm for the square arrangement with CdTe shell thickness of 40-60 nm. The effects of the CdTe shell thickness on the absorption of ZnO/CdTe NW arrays are revealed through the study of two optical key modes: the first one is confining the light into individual NWs, the second one is strongly interacting with the NW arrangement. It is also shown that the reflectivity of the substrate can improve Fabry-Perot resonances within the NWs: the ideal short-circuit current density is increased by 10% for the ZnO/fluorine-doped tin oxide (FTO)/ideal reflector as compared to the ZnO/FTO/glass substrate. Furthermore, the optimized square arrangement absorbs light more efficiently than both optimized hexagonal and triangular arrangements. Eventually, the enhancement factor of the ideal short-circuit current density is calculated as high as 1.72 with respect to planar layers, showing the high optical potentiality of ZnO/CdTe core-shell NW arrays. PMID:25629373

  17. The influence of negative ionization of the air on motor activity in Syrian hamsters ( Masocricetus auratus Waterhouse) in light conditions

    NASA Astrophysics Data System (ADS)

    Lenkiewicz, Zofia; Dabrowska, Barbara; Schiffer, Zofia

    1989-12-01

    The motor activity of Syrian hamsters ( Mesocricetus auratus Waterhouse) under the influence of negative ionization of the atmosphere applied for 10, 20 or 30 min per day was investigated. An ionizer with output of 14000 light negative ions per 1 cm3 of air was used. Studies carried out in the light phase of a 12∶12 h light/dark regime revealed a relation between the reaction of the animal and the time of day at which ionization was applied. Ionization for 20 or 30 min in the light phase decreased motor activity, while 10 min of ionization increased it compared to control animals. Ionization in the dark phase gave a more distinct rise in activity than that applied in the light phase for all three durations of ionization.

  18. A centrifugal ice microtome for measurements of atmospheric CO2 on air trapped in polar ice cores

    NASA Astrophysics Data System (ADS)

    Bereiter, B.; Stocker, T. F.; Fischer, H.

    2012-10-01

    For atmospheric CO2 reconstructions using ice cores, the technique to release the trapped air from the ice samples is crucial for the precision and accuracy of the measurements. We present here a new dry extraction technique in combination with a new gas analytical system that together show significant improvements with respect to current systems. Ice samples (3-15 g) are pulverized using a novel Centrifugal Ice Microtome (CIM) by shaving the ice in a cooled vacuum chamber (-27 °C) in which no friction occurs due to the use of magnetic bearings. Both, the shaving principle of the CIM and the use of magnetic bearings have not been applied so far in this field. Shaving the ice samples produces finer ice powder and releases a minimum of 90% of the trapped air compared to 50%-70% when needle crushing is employed. In addition, the friction-free motion with an optimized design to reduce contaminations of the inner surfaces of the device result in a reduced system offset of about 2.0 ppmv compared to 4.9ppmv. The gas analytical part shows a factor two higher precision than our corresponding part of the previous system and all processes except the loading and cleaning of the CIM now run automatically. Compared to our previous system the new system shows a 3 times better measurement reproducibility of about 1.1 ppmv (1σ) which is similar to the best reproducibility of other systems applied in this field. With this high reproducibility, replicate measurements are not required anymore for most prospective measurement campaigns resulting in a possible output of 12-20 measurements per day compared to a maximum of 6 with other systems.

  19. A centrifugal ice microtome for measurements of atmospheric CO2 on air trapped in polar ice cores

    NASA Astrophysics Data System (ADS)

    Bereiter, B.; Stocker, T. F.; Fischer, H.

    2013-02-01

    For atmospheric CO2 reconstructions using ice cores, the technique to release the trapped air from the ice samples is essential for the precision and accuracy of the measurements. We present here a new dry extraction technique in combination with a new gas analytical system that together show significant improvements with respect to current systems. Ice samples (3-15 g) are pulverised using a novel centrifugal ice microtome (CIM) by shaving the ice in a cooled vacuum chamber (-27 °C) in which no friction occurs due to the use of magnetic bearings. Both, the shaving principle of the CIM and the use of magnetic bearings have not been applied so far in this field. Shaving the ice samples produces finer ice powder and releases a minimum of 90% of the trapped air compared to 50%-70% when needle crushing is employed. In addition, the friction-free motion with an optimized design to reduce contaminations of the inner surfaces of the device result in a reduced system offset of about 2.0 ppmv compared to 4.9 ppmv. The gas analytical part shows a higher precision than the corresponding part of our previous system by a factor of two, and all processes except the loading and cleaning of the CIM now run automatically. Compared to our previous system, the complete system shows a 3 times better measurement reproducibility of about 1.1 ppmv (1 σ) which is similar to the best reproducibility of other systems applied in this field. With this high reproducibility, no replicate measurements are required anymore for most future measurement campaigns resulting in a possible output of 12-20 measurements per day compared to a maximum of 6 with other systems.

  20. Efficient polymer light-emitting diode with air-stable aluminum cathode

    NASA Astrophysics Data System (ADS)

    Abbaszadeh, D.; Wetzelaer, G. A. H.; Doumon, N. Y.; Blom, P. W. M.

    2016-03-01

    The fast degradation of polymer light-emitting diodes (PLEDs) in ambient conditions is primarily due to the oxidation of highly reactive metals, such as barium or calcium, which are used as cathode materials. Here, we report the fabrication of PLEDs using an air-stable partially oxidized aluminum (AlOx) cathode. Usually, the high work function of aluminum (4.2 eV) imposes a high barrier for injecting electrons into the lowest unoccupied molecular orbital (LUMO) of the emissive polymer (2.9 eV below the vacuum level). By partially oxidizing aluminum, its work function is decreased, but not sufficiently low for efficient electron injection. Efficient injection is obtained by inserting an electron transport layer of poly[(9,9-di-n-octylfluorenyl-2,7-diyl)-alt-(benzo[2,1,3]thiadiazol-4,8-diyl)] (F8BT), which has its LUMO at 3.3 eV below vacuum, between the AlOx cathode and the emissive polymer. The intermediate F8BT layer not only serves as a hole-blocking layer but also provides an energetic staircase for electron injection from AlOx into the emissive layer. PLEDs with an AlOx cathode and F8BT interlayer exhibit a doubling of the efficiency as compared to conventional Ba/Al PLEDs, and still operate even after being kept in ambient atmosphere for one month without encapsulation.

  1. Lighting.

    SciTech Connect

    United States. Bonneville Power Administration.

    1992-09-01

    Since lighting accounts for about one-third of the energy used in commercial buildings, there is opportunity to conserve. There are two ways to reduce lighting energy use: modify lighting systems so that they used less electricity and/or reduce the number of hours the lights are used. This booklet presents a number of ways to do both. Topics covered include: reassessing lighting levels, reducing lighting levels, increasing bulb & fixture efficiency, using controls to regulate lighting, and taking advantage of daylight.

  2. Aerodynamic performance of a fully film cooled core turbine vane tested with cold air in a two-dimensional cascade

    NASA Technical Reports Server (NTRS)

    Stabe, R. G.; Kline, J. F.

    1975-01-01

    The aerodynamic performance of a fully film cooled core turbine vane was investigated experimentally in a two-dimensional cascade of 10 vanes. Three of the 10 vanes were cooled; the others were solid (uncooled) vanes. Cold air was used for both the primary and coolant flows. The cascade test covered a range of pressure ratios corresponding to ideal exit critical velocity ratios of 0.6 to 0.95 and a range of coolant flow rates to 7.5 percent of the primary flow. The coolant flow was varied by changing the coolant supply pressure. The principal measurements were cross-channel surveys of exit total pressure, static pressure, and flow angle. The results presented include exit survey data and overall performance in terms of loss, flow angle, and weight flow for the range of exit velocity ratios and coolant flows investigated. The performance of the cooled vane is compared with the performance of an uncooled vane of the same profile and also with the performance obtained with a single cooled vane in the 10-vane cascade.

  3. Computational Assessment of the GT-MHR Graphite Core Support Structural Integrity in Air-Ingress Accident Condition

    SciTech Connect

    Jong B. Lim; Eung S. Kim; Chang H. Oh; Richard R. Schultz; David A. Petti

    2008-10-01

    The objective of this project was to perform stress analysis for graphite support structures of the General Atomics’ 600 MWth GT-MHR prismatic core design using ABAQUS ® (ver. 6.75) to assess their structural integrity in air-ingress accident conditions where the structure weakens over time due to oxidation damages. The graphite support structures of prismatic type GT-MHR was analyzed based on the change of temperature, burn-off and corrosion depth during the accident period predicted by GAMMA, a multi-dimensional gas multi-component mixture analysis code developed in the Republic of Korea (ROK)/United States (US) International –Nuclear Engineering Research Initiative (I-NERI) project. Both the loading and thermal stresses were analyzed, but the thermal stress was not significant, leaving the loading stress to be the major factor. The mechanical strengths are exceeded between 11 to 11.5 days after loss-of-coolant-accident (LOCA), corresponding to 5.5 to 6 days after the start of natural convection.

  4. Temperature dependence of beat-length and confinement loss in an air-core photonic band-gap fiber

    NASA Astrophysics Data System (ADS)

    Xu, Zhenlong; Li, Xuyou; Hong, Yong; Liu, Pan; Yang, Hanrui; Ling, Weiwei

    2016-05-01

    The temperature dependence of polarization-maintaining (PM) property and loss in a highly-birefringent air-core photonic band-gap fiber (PBF) is investigated. The effects of temperature variation on the effective index, beat-length and confinement loss are studied numerically by using the full-vector finite element method (FEM). It is found that, the PM property of this PBF is insensitive to the temperature, and the temperature-dependent beat-length coefficient can be as low as 2.86×10-8 m/°C, which is typically 200 times less than those of conventional panda fibers, the PBF has a stable confinement loss of 0.01 dB/m over the temperature range of -30 to 20 °C for the slow axis at the wavelength of 1.55 μm. The PBF with ultra-low temperature-dependent PM property and low loss can reduce the thermally induced polarization instability apparently in interferometric applications such as resonant fiber optic gyroscope (RFOG), optical fiber sensors, and so on.

  5. Air-void embedded GaN-based light-emitting diodes grown on laser drilling patterned sapphire substrates

    NASA Astrophysics Data System (ADS)

    Liu, Hao; Li, Yufeng; Wang, Shuai; Feng, Lungang; Xiong, Han; Su, Xilin; Yun, Feng

    2016-07-01

    Air-void structure was introduced in GaN-based blue light-emitting diodes (LED) with one-step growth on periodic laser drilling patterned sapphire substrate, which free of any photolithography or wet/dry etching process. The influence of filling factors (FF) of air-void on crystal quality and optical performance were investigate. Transmission electron microscopy images and micro-Raman spectroscopy indicated that the dislocation was bended and the partially compressed strain was released. When FF was 55.43%, compared with the LED structure grown on flat sapphire substrate, the incorporation of air-void was observed to reduce the compressed stress of ˜20% and the luminance intensity has improved by 128%. Together with the simulated reflection intensity enhancement by finite difference time-domain (FDTD) method, we attribute the enhanced optical performance to the combined contribution of strong back-side light reflection of air-void and better GaN epitaxial quality. This approach provides a simple replacement to the conventional air-void embedded LED process.

  6. Effects of lighting and air movement on temperatures in reproductive organs of plants in a closed plant growth facility

    NASA Astrophysics Data System (ADS)

    Kitaya, Y.; Hirai, H.

    Temperature increases in plant reproductive organs such as anthers and stigmas could cause fertility impediments and thus produce sterile seeds under artificial lighting conditions without adequately controlled environments in closed plant growth facilities. There is a possibility such a situation could occur in Bioregenerative Life Support Systems under microgravity conditions in space because there will be little natural convective or thermal mixing. This study was conducted to determine the temperature of the plant reproductive organs as affected by illumination and air movement under normal gravitational forces on the earth and to make an estimation of the temperature increase in reproductive organs in closed plant growth facilities under microgravity in space. Thermal images of reproductive organs of rice and strawberry were captured using infrared thermography at air temperatures of 10 11 °C. Compared to the air temperature, temperatures of petals, stigmas and anthers of strawberry increased by 24, 22 and 14 °C, respectively, after 5 min of lighting at an irradiance of 160 W m-2 from incandescent lamps. Temperatures of reproductive organs and leaves of strawberry were significantly higher than those of rice. The temperatures of petals, stigmas, anthers and leaves of strawberry decreased by 13, 12, 13 and 14 °C, respectively, when the air velocity was increased from 0.1 to 1.0 ms-1. These results show that air movement is necessary to reduce the temperatures of plant reproductive organs in plant growth facilities.

  7. Summary report on effects at temperature, humidity, and fuel-air ratio on two air-cooled light aircraft engines

    NASA Technical Reports Server (NTRS)

    Kempke, E. E., Jr.

    1976-01-01

    Five different engine models were tested to experimentally characterize emissions and to determine the effects of variation in fuel-air ratio and spark timing on emissions levels and other operating characteristics such as cooling, misfiring, roughness, power acceleration, etc. The results are given of two NASA reports covering the Avco Lycoming 0-320-D engine testing and the recently obtained results on the Teledyne Continental TSIO-360-C engine.

  8. Investigating the Cherenkov light lateral distribution function for primary proton and iron nuclei in extensive air showers

    NASA Astrophysics Data System (ADS)

    Al-Rubaiee, A. A.; Hashim, U.; Al-Douri, Y.

    2015-11-01

    The lateral distribution function (LDF) of Cherenkov radiation in extensive air showers (EAS) was simulated by CORSIKA program for the conditions of Yakutsk Cherenkov array at the high energy range (1013-1016) eV for two primary particles (p and Fe) for different zenith angles. By depending on Breit-Wigner function for analyzing of Cherenkov light LDF, a parameterization of Cherenkov light LDF was reconstructed by depending on CORSIKA simulation as a function of primary energy. The comparison between the estimated Cherenkov light LDF with the LDF that measured on the Yakutsk EAS array gives the ability of particle identification that initiated the shower and determination of particle's energy around the knee region. The extrapolation of approximated Cherenkov light LDF for energies 20 and 30 PeV was obtained for primary particles (p and Fe).

  9. Formation of alkenes and oxygenated VOCs from light mediated surface chemistry of nonanoic acid at the air-seawater interface

    NASA Astrophysics Data System (ADS)

    Gonzalez, L.; Volkamer, R.; Ciuraru, R.; Bernard, F.; George, C.

    2013-12-01

    Organic carbon is relevant in the atmosphere because it affects oxidative capacity that determines the removal rate of climate active gases and modifies aerosols. The significant presence of organic compounds at the surface of the ocean is a source for primary and secondary aerosol formation that potentially can modify cloud cover. Field observations of glyoxal over the remote marine boundary layer, and the tropical free troposphere remain unexplained by atmospheric models, and indicate missing sources of marine organic carbon species from heterogeneous processes mediated by light. We have studied the light induced surface chemistry of synthetic aqueous -mixtures containing NaCl, NaBr, NaI, photosensitizers (humic acids) and an organic surfactant (nonanoic acid) in a photochemical Quartz flowreactor. The air from the flowreactor was transferred to a dark reactor where the products from photosensitized reactions at the air/sea interface were further exposed to ozone. The products were sampled in the presence/absence of light and ozone by Proton Transfer Reaction Time of Flight Mass Spectrometry (PTR-ToF-MS) and Light-Emitting-Diode Cavity-Enhanced Differential Optical Absorption Spectroscopy (LED-CE-DOAS). In the presence of light nonenal formation is observed. Addition of ozone leads to the formation of glyoxal, among other products. Further experiments were conducted in an atmospheric simulation chamber. We discuss first results and atmospheric implications.

  10. MULTI-COLOR OPTICAL AND NEAR-INFRARED LIGHT CURVES OF 64 STRIPPED-ENVELOPE CORE-COLLAPSE SUPERNOVAE

    SciTech Connect

    Bianco, F. B.; Modjaz, M.; Hicken, M.; Friedman, A.; Kirshner, R. P.; Challis, P.; Marion, G. H.; Bloom, J. S.; Wood-Vasey, W. M.; Rest, A.

    2014-08-01

    We present a densely sampled, homogeneous set of light curves of 64 low-redshift (z ≲ 0.05) stripped-envelope supernovae (SNe of Type IIb, Ib, Ic, and Ic-BL). These data were obtained between 2001 and 2009 at the Fred L. Whipple Observatory (FLWO) on Mount Hopkins in Arizona, with the optical FLWO 1.2 m and the near-infrared (NIR) Peters Automated Infrared 1.3 m telescopes. Our data set consists of 4543 optical photometric measurements on 61 SNe, including a combination of U BV RI, U BV r{sup ′}i{sup ′}, and u{sup ′} BV r{sup ′}i{sup ′}, and 1919 JHK{sub s} NIR measurements on 25 SNe. This sample constitutes the most extensive multi-color data set of stripped-envelope SNe to date. Our photometry is based on template-subtracted images to eliminate any potential host-galaxy light contamination. This work presents these photometric data, compares them with data in the literature, and estimates basic statistical quantities: date of maximum, color, and photometric properties. We identify promising color trends that may permit the identification of stripped-envelope SN subtypes from their photometry alone. Many of these SNe were observed spectroscopically by the Harvard-Smithsonian Center for Astrophysics (CfA) SN group, and the spectra are presented in a companion paper. A thorough exploration that combines the CfA photometry and spectroscopy of stripped-envelope core-collapse SNe will be presented in a follow-up paper.

  11. High-power phosphor-free InGaN/AlGaN dot-in-a-wire core-shell white light-emitting diodes

    NASA Astrophysics Data System (ADS)

    Nguyen, Hieu P. T.; Djavid, Mehrdad; Woo, Steffi Y.; Liu, Xianhe; Wang, Qi; Botton, Gianluigi A.; Mi, Zetian

    2015-03-01

    We report on the achievement of relatively high power phosphor-free white light-emitting diodes (LEDs) using a new self-organized InGaN/AlGaN dot-in-a-wire core-shell nanowire heterostructure. Multiple AlGaN shell layers are spontaneously formed during the growth of the quantum dot active region. Due to the drastically reduced nonradiative surface recombination, such core-shell nanowire structures exhibit significantly increased carrier lifetime (from ~ 0.3ns to ~ 4.5ns) and massively enhanced photoluminescence intensity. Strong white-light emission was recorded for the unpackaged core-shell nanowire LEDs with an output power of >5 mW, measured under an injection current ~ 60A/cm2, with a color rendering index of ~ 95.

  12. Laser sheet light flow visualization for evaluating room air flowsfrom Registers

    SciTech Connect

    Walker, Iain S.; Claret, Valerie; Smith, Brian

    2006-04-01

    Forced air heating and cooling systems and whole house ventilation systems deliver air to individual rooms in a house via supply registers located on walls ceilings or floors; and occasionally less straightforward locations like toe-kicks below cabinets. Ideally, the air velocity out of the registers combined with the turbulence of the flow, vectoring of air by register vanes and geometry of register placement combine to mix the supply air within the room. A particular issue that has been raised recently is the performance of multiple capacity and air flow HVAC systems. These systems vary the air flow rate through the distribution system depending on the system load, or if operating in a ventilation rather than a space conditioning mode. These systems have been developed to maximize equipment efficiency, however, the high efficiency ratings do not include any room mixing effects. At lower air flow rates, there is the possibility that room air will be poorly mixed, leading to thermal stratification and reduced comfort for occupants. This can lead to increased energy use as the occupants adjust the thermostat settings to compensate and parts of the conditioned space have higher envelope temperature differences than for the well mixed case. In addition, lack of comfort can be a barrier to market acceptance of these higher efficiency systems To investigate the effect on room mixing of reduced air flow rates requires the measurement of mixing of supply air with room air throughout the space to be conditioned. This is a particularly difficult exercise if we want to determine the transient performance of the space conditioning system. Full scale experiments can be done in special test chambers, but the spatial resolution required to fully examine the mixing problem is usually limited by the sheer number of thermal sensors required. Current full-scale laboratory testing is therefore severely limited in its resolution. As an alternative, we used a water-filled scale model

  13. Uniform silicon slow light waveguide

    NASA Astrophysics Data System (ADS)

    Jiang, C.

    2011-01-01

    An uniform silicon waveguide is proposed featuring ultralow-dispersion slow light. The core of the waveguide consists of one silicon trip and two pairs of air/silicon strip and the cladding is composed of several alternative silicon and air strips, which form a transverse band gap to confine propagating light in the core. The waveguide has several nearly linear photonic bands in a large frequency range, which can support broadband slow modes with a group velocity of 0.03-0.08 c and tolerable group velocity dispersion.

  14. Visible-light induced isoindoles formation to trigger intermolecular Diels-Alder reactions in the presence of air.

    PubMed

    Lin, Chao; Zhen, Le; Cheng, Yong; Du, Hong-Jin; Zhao, Hui; Wen, Xiaoan; Kong, Ling-Yi; Xu, Qing-Long; Sun, Hongbin

    2015-06-01

    Visible-light induced isoindole formation triggered an intermolecular Diels-Alder reaction with dienophiles such as acetylenedicarboxylate and maleimides in the presence of air. The reaction resulted in excellent diastereoselctivity and high yields under mild reaction conditions. This protocol provides an atom-economical, transition-metal-free (TM-free) and straightforward approach to structurally diverse bridged-ring heterocycles from easily accessible molecules.

  15. Ce Core-Level Spectroscopy, and Magnetic and Electrical Transport Properties of Lightly Ce-Doped YCoO3

    NASA Astrophysics Data System (ADS)

    Kobayashi, Yoshihiko; Koike, Tsuyoshi; Okawa, Mario; Takayanagi, Ryohei; Takei, Shohei; Minohara, Makoto; Kobayashi, Masaki; Horiba, Koji; Kumigashira, Hiroshi; Yasui, Akira; Ikenaga, Eiji; Saitoh, Tomohiko; Asai, Kichizo

    2016-11-01

    We have investigated the Ce and Co core level spectroscopy, and the magnetic and electrical transport properties of lightly Ce-doped YCoO3. We have successfully synthesized single-phase Y1-xCexCoO3 for 0.0 ≤ x ≤ 0.1 by the sol-gel method. Hard X-ray photoelectron and X-ray absorption spectroscopy experiments reveal that the introduced Ce ions are tetravalent, which is considered to be the first case of electron doping into bulk trivalent Co oxides with perovskite RECoO3 (RE: rare-earth element or Y) caused by RE site substitution. The magnitude of the effective magnetic moment peff obtained from the temperature dependence of magnetic susceptibility χ(T) at higher temperatures is close to that for high-spin Co2+ introduced by the Ce doping, implying that the electrons doped into the Co site induce Co2+ with a high-spin state. For x = 0.1, ferromagnetic ordering is observed below about 7 K. Electrical transport properties such as resistivity and thermoelectric power show that negative electron-like carriers are introduced by Ce substitution.

  16. The proteolysis adaptor, NblA, is essential for degradation of the core pigment of the cyanobacterial light-harvesting complex.

    PubMed

    Sendersky, Eleonora; Kozer, Noga; Levi, Mali; Moizik, Michael; Garini, Yuval; Shav-Tal, Yaron; Schwarz, Rakefet

    2015-09-01

    The cyanobacterial light-harvesting complex, the phycobilisome, is degraded under nutrient limitation, allowing the cell to adjust light absorbance to its metabolic capacity. This large light-harvesting antenna comprises a core complex of the pigment allophycocyanin, and rod-shaped pigment assemblies emanating from the core. NblA, a low-molecular-weight protein, is essential for degradation of the phycobilisome. NblA mutants exhibit high absorbance of rod pigments under conditions that generally elicit phycobilisome degradation, implicating NblA in degradation of these pigments. However, the vast abundance of rod pigments and the substantial overlap between the absorbance spectra of rod and core pigments has made it difficult to directly associate NblA with proteolysis of the phycobilisome core. Furthermore, lack of allophycocyanin degradation in an NblA mutant may reflect a requirement for rod degradation preceding core degradation, and does not prove direct involvement of NblA in proteolysis of the core pigment. Therefore, in this study, we used a mutant lacking phycocyanin, the rod pigment of Synechococcus elongatusPCC7942, to examine whether NblA is required for allophycocyanin degradation. We demonstrate that NblA is essential for degradation of the core complex of the phycobilisome. Furthermore, fluorescence lifetime imaging microscopy provided in situ evidence for the interaction of NblA with allophycocyanin, and indicated that NblA interacts with allophycocyanin complexes that are associated with the photosynthetic membranes. Based on these data, as well as previous observations indicating interaction of NblA with phycobilisomes attached to the photosynthetic membranes, we suggest a model for sequential phycobilisome disassembly by NblA. PMID:26173720

  17. Fast fabrication of copper nanowire transparent electrodes by a high intensity pulsed light sintering technique in air.

    PubMed

    Ding, Su; Jiu, Jinting; Tian, Yanhong; Sugahara, Tohru; Nagao, Shijo; Suganuma, Katsuaki

    2015-12-14

    Copper nanowire transparent electrodes have received increasing interest due to the low price and nearly equal electrical conductivity compared with other TEs based on silver nanowires and indium tin oxide (ITO). However, a post-treatment at high temperature in an inert atmosphere or a vacuum environment was necessary to improve the conductivity of Cu NW TEs due to the easy oxidation of copper in air atmosphere, which greatly cancelled out the low price advantage of Cu NWs. Here, a high intensity pulsed light technique was introduced to sinter and simultaneously deoxygenate these Cu NWs into a highly conductive network at room temperature in air. The strong light absorption capacity of Cu NWs enabled the welding of the nanowires at contact spots, as well as the removal of the thin layer of residual organic compounds, oxides and hydroxide of copper even in air. The Cu NW TE with a sheet resistance of 22.9 Ohm sq(-1) and a transparency of 81.8% at 550 nm has been successfully fabricated within only 6 milliseconds exposure treatment, which is superior to other films treated at high temperature in a hydrogen atmosphere. The HIPL process was simple, convenient and fast to fabricate easily oxidized Cu NW TEs in large scale in an air atmosphere, which will largely extend the application of cheap Cu NW TEs.

  18. Fast fabrication of copper nanowire transparent electrodes by a high intensity pulsed light sintering technique in air.

    PubMed

    Ding, Su; Jiu, Jinting; Tian, Yanhong; Sugahara, Tohru; Nagao, Shijo; Suganuma, Katsuaki

    2015-12-14

    Copper nanowire transparent electrodes have received increasing interest due to the low price and nearly equal electrical conductivity compared with other TEs based on silver nanowires and indium tin oxide (ITO). However, a post-treatment at high temperature in an inert atmosphere or a vacuum environment was necessary to improve the conductivity of Cu NW TEs due to the easy oxidation of copper in air atmosphere, which greatly cancelled out the low price advantage of Cu NWs. Here, a high intensity pulsed light technique was introduced to sinter and simultaneously deoxygenate these Cu NWs into a highly conductive network at room temperature in air. The strong light absorption capacity of Cu NWs enabled the welding of the nanowires at contact spots, as well as the removal of the thin layer of residual organic compounds, oxides and hydroxide of copper even in air. The Cu NW TE with a sheet resistance of 22.9 Ohm sq(-1) and a transparency of 81.8% at 550 nm has been successfully fabricated within only 6 milliseconds exposure treatment, which is superior to other films treated at high temperature in a hydrogen atmosphere. The HIPL process was simple, convenient and fast to fabricate easily oxidized Cu NW TEs in large scale in an air atmosphere, which will largely extend the application of cheap Cu NW TEs. PMID:26536570

  19. Bicolor Mn-doped CuInS{sub 2}/ZnS core/shell nanocrystals for white light-emitting diode with high color rendering index

    SciTech Connect

    Huang, Bo; Dai, Qian; Zhang, Huichao; Liao, Chen; Cui, Yiping; Zhang, Jiayu; Zhuo, Ningze; Jiang, Qingsong; Shi, Fenghua; Wang, Haibo

    2014-09-07

    We synthesized bicolor Mn-doped CuInS{sub 2} (CIS)/ZnS core/shell nanocrystals (NCs), in which Mn{sup 2+} ions and the CIS core were separated with a ZnS layer, and both Mn{sup 2+} ions and CIS cores could emit simultaneously. Transmission electron microscopy and powder X-ray diffraction measurements indicated the epitaxial growth of ZnS shell on the CuInS{sub 2} core, and electron paramagnetic resonance spectrum indicated that Mn{sup 2+} ions were on the lattice points of ZnS shell. By integrating these bicolor NCs with commercial InGaN-based blue-emitting diodes, tricolor white light-emitting diodes with color rendering index of 83 were obtained.

  20. Achieving enhanced visible-light-driven photocatalysis using type-II NaNbO3/CdS core/shell heterostructures.

    PubMed

    Kumar, Sandeep; Khanchandani, Sunita; Thirumal, Meganathan; Ganguli, Ashok K

    2014-08-13

    Expanding the light-harvesting range and suppressing the quick recombination of photogenerated charge carriers are of paramount significance in the field of photocatalysis. One possible approach to achieve wide absorption range is to synthesize type-II core/shell heterostructures. In addition, this system also shows great promise for fast separation of charge carriers and low charge recombination rate. Herein, following the surface functionalization method using 3-mercaptopropionic acid (MPA) as a surface functionalizing agent, we report on designing NaNbO3/CdS type-II core/shell heterostructures with an absorption range extending to visible range and explore the opportunity toward degradation of methylene blue (MB) dye as a model pollutant under visible light irradiation. Characterizations including X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), UV-vis diffuse reflectance spectrum (DRS), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS), and Raman spectroscopy support the growth of CdS shell onto NaNbO3 nanorods. The resulting core/shell heterostructures unveiled high surface areas, enhanced light harvesting, and appreciably increased photocatalytic activity toward MB degradation compared to individual counterparts and the photocatalytic standard, Degussa P25, under visible light irradiation. The remarkably enhanced photocatalytic activity of core/shell heterostructures could be interpreted in terms of efficient charge separation owing to core/shell morphology and resulting type-II band alignment between NaNbO3 and CdS, which creates a step-like radial potential favoring the localization of one of the carriers in the core and the other in the shell. A plausible mechanism for the degradation of MB dye over NaNbO3/CdS core/shell heterostructures is also elucidated using active species scavenger studies. Our findings imply that hydroxyl radicals (OH(•)) play a crucial role in dictating the degradation

  1. Hollow Au-Cu2O Core-Shell Nanoparticles with Geometry-Dependent Optical Properties as Efficient Plasmonic Photocatalysts under Visible Light.

    PubMed

    Lu, Biao; Liu, Aiping; Wu, Huaping; Shen, Qiuping; Zhao, Tingyu; Wang, Jianshan

    2016-03-29

    Hollow Au-Cu2O core-shell nanoparticles were synthesized by using hollow gold nanoparticles (HGNs) as the plasmon-tailorable cores to direct epitaxial growth of Cu2O nanoshells. The effective geometry control of hollow Au-Cu2O core-shell nanoparticles was achieved through adjusting the HGN core sizes, Cu2O shell thicknesses, and morphologies related to structure-directing agents. The morphology-dependent plasmonic band red-shifts across the visible and near-infrared spectral regions were observed from experimental extinction spectra and theoretical simulation based on the finite-difference time-domain method. Moreover, the hollow Au-Cu2O core-shell nanoparticles with synergistic optical properties exhibited higher photocatalytic performance in the photodegradation of methyl orange when compared to pristine Cu2O and solid Au-Cu2O core-shell nanoparticles under visible-light irradiation due to the efficient photoinduced charge separation, which could mainly be attributed to the Schottky barrier and plasmon-induced resonant energy transfer. Such optical tunability achieved through the hollow cores and structure-directed shells is of benefit to the performance optimization of metal-semiconductor nanoparticles for photonic, electronic, and photocatalytic applications. PMID:26954100

  2. Direct observation of a resolvable spin separation in the spin Hall effect of light at an air-glass interface

    SciTech Connect

    Ren, Jin-Li; Wang, Bo; Xiao, Yun-Feng; Gong, Qihuang; Li, Yan

    2015-09-14

    We theoretically and experimentally demonstrate that it is possible to directly observe the resolvable spin separation in the spin Hall effect of light at an air-glass interface by choosing optimal parameters. When a P-polarized light with a beam waist of 10 μm is incident around Brewster's angle, the two spin components of the reflected beam can be completely separated by eliminating the influence of the in-plane wavevector spread. This not only obviously reveals the strong impacts of the polarization state, the incident angle, the beam waist, and the in-plane wavevector spread, but also intuitively visualizes the observation of the spin Hall effect of light.

  3. Photon management with core-shell nanowire structures.

    PubMed

    Lai, Kun-Yu; Chang, Hung-Chih; Dai, Yu-An; He, Jr-Hau

    2012-03-12

    Antireflective Si/oxide core-shell nanowire arrays (NWAs) were fabricated by galvanic etching and subsequent annealing process. The excellent light-harvesting characteristics of the core-shell NWAs, such as broadband working ranges, omnidirectionality, and polarization-insensitivity, ascribed to the smooth index transition from air to the substrates, have been demonstrated. By tuning core-shell volume ratios, we obtained enhanced light trapping regions implemented in either the planar Si underneath NWAs or the core regions of NWAs, greatly benefiting the geometry design of planar and radial p-n junction cell structures, respectively. This photon management scheme indicates the potential use in nanostructured photovoltaic applications. PMID:22418674

  4. Progress report on a new search for free e/3 quarks in the cores of 10(15) - 10(16) eV air showers

    NASA Technical Reports Server (NTRS)

    Hodson, A. L.; Bull, R. M.; Taylor, R. S.; Belford, C. H.

    1985-01-01

    The Leeds 3 sq m Wilson cloud chamber is being used in a new search for free e/3 quarks close to the axes of 10 to the 15th power - 10 to the 16th power eV air showers. A ratio trigger circuit is used to detect the incidence of air shower cores; the position of the shower center and the axis direction are determined from photographs of current-limited spark chambers. It is thus possible, for the first time, to know where we have looked for quarks in air showers and to select for scanning only those cloud chamber photographs where we have good evidence that the shower axis was close to the chamber. 250 g/sq cm of lead/concrete absorber above the cloud chamber serve to reduce particle densities and make a quark search possible very close to the shower axes. The current status of the search is given.

  5. Initial measurements of CO2 concentrations (1530 to 1940 AD) in air occluded in the GISP 2 Ice Core from central Greenland

    NASA Astrophysics Data System (ADS)

    Wahlen, M.; Allen, D.; Deck, B.; Herchenroder, A.

    Initial measurements of CO2 in the air of bubbles in the GISP 2 (Greenland Ice Sheet Project 2) ice core were performed using a dry extraction technique and tunable diode laser absorption spectroscopy. The record spans the years 1530 to 1940, and includes part of the little ice age. Absolute dating of the air was obtained from the location of the 14CO2 bomb peak in the bubble air, relative dating from the seasonal variations of H218O and electro-conductivity. The results for preindustrial times indicate constant atmospheric CO2 levels of 280±5 ppmv between 1530 and 1810 AD. Thereafter the concentrations rise rather abruptly. The record smoothly connects to the direct atmospheric observations from Mauna Loa.

  6. Emissions of an AVCO Lycoming 0-320-DIAD air cooled light aircraft engine as a function of fuel-air ratio, timing, and air temperature and humidity

    NASA Technical Reports Server (NTRS)

    Meng, P. R.; Skorobatckyi, M.; Cosgrove, D. V.; Kempke, E. E., Jr.

    1976-01-01

    A carbureted aircraft engine was operated over a range of test conditions to establish the exhaust levels over the EPA seven-mode emissions cycle. Baseline (full rich production limit) exhaust emissions at an induction air temperature of 59 F and near zero relative humidity were 90 percent of the EPA standard for HC, 35 percent for NOx, and 161 percent for CO. Changes in ignition timing around the standard 25 deg BTDC from 30 deg BTDC to 20 deg BTDC had little effect on the exhaust emissions. Retarding the timing to 15 deg BTDC increased both the HC and CO emissions and decreased NOx emissions. HC and CO emissions decreased as the carburetor was leaned out, while NOx emissions increased. The EPA emission standards were marginally achieved at two leanout conditions. Variations in the quantity of cooling air flow over the engine had no effect on exhaust emissions. Temperature-humidity effects at the higher values of air temperature and relative humidity tested indicated that the HC and CO emissions increased significantly, while the NOx emissions decreased.

  7. Do-It-Yourself Air Sensors – Exploring the Atmosphere and Turning on Light Bulbs!?

    EPA Science Inventory

    These are educational slides that will be presented in a webinar to the National Science Teachers Association. Topics covered include general air quality, current EPA research, and EPA's particle sensor kit that is a classroom activity.

  8. Effect of Intake Air Filter Condition on Light-Duty Gasoline Vehicles

    SciTech Connect

    Thomas, John F; Huff, Shean P; West, Brian H; Norman, Kevin M

    2012-01-01

    Proper maintenance can help vehicles perform as designed, positively affecting fuel economy, emissions, and the overall drivability. This effort investigates the effect of one maintenance factor, intake air filter replacement, with primary focus on vehicle fuel economy, but also examining emissions and performance. Older studies, dealing with carbureted gasoline vehicles, have indicated that replacing a clogged or dirty air filter can improve vehicle fuel economy and conversely that a dirty air filter can be significantly detrimental to fuel economy. The effect of clogged air filters on the fuel economy, acceleration and emissions of five gasoline fueled vehicles is examined. Four of these were modern vehicles, featuring closed-loop control and ranging in model year from 2003 to 2007. Three vehicles were powered by naturally aspirated, port fuel injection (PFI) engines of differing size and cylinder configuration: an inline 4, a V6 and a V8. A turbocharged inline 4-cylinder gasoline direct injection (GDI) engine powered vehicle was the fourth modern gasoline vehicle tested. A vintage 1972 vehicle equipped with a carburetor (open-loop control) was also examined. Results reveal insignificant fuel economy and emissions sensitivity of modern vehicles to air filter condition, but measureable effects on the 1972 vehicle. All vehicles experienced a measured acceleration performance penalty with clogged intake air filters.

  9. Efficient photocatalytic removal of NO in indoor air with hierarchical bismuth oxybromide nanoplate microspheres under visible light.

    PubMed

    Ai, Zhihui; Ho, Wingkei; Lee, Shuncheng; Zhang, Lizhi

    2009-06-01

    In this study, hierarchical bismuth oxybromide (BiOBr) nanoplate microspheres were used to remove NO in indoor air under visible light irradiation. The BiOBr microspheres were synthesized with a nonaqueous sol-gel method by using bismuth nitrate and cetyltrimethyl ammonium bromide as the precursors. On degradation of NO under visible light irradiation (lambda > 420 nm) at 400 part-per-billion level, which is typical concentration for indoor air quality, these nonaqueous sol-gel synthesized hierarchical BiOBr microspheres exhibited superior photocatalytic activity to the chemical precipitation synthesized counterpart BiOBr bulk powder and Degussa TiO2 P25 as well as C doped TiO2. The excellent catalytic activity and the long-term activity of nonaqueous sol-gel synthesized BiOBr microspheres were attributed to their special hierarchical structure, which was favorable for the diffusion of intermediates and final products of NO oxidation. Ion chromatograph results confirmed that nitric acid was produced on the surface of BiOBr microspheres during the photooxidation of NO in gas phase. This work suggests that the nonaqueous sol-gel synthesized BiOBr nanoplate microspheres are promising photocatalytic materials for indoor air purification. PMID:19569343

  10. Low-loss light coupling with graded-index core polymer optical waveguides via 45-degree mirrors.

    PubMed

    Morimoto, Yoshie; Ishigure, Takaaki

    2016-02-22

    We experimentally investigate the optical loss of graded-index (GI) core polymer optical waveguides with a 45-degree mirror on their one end fabricated using the photo-addressing method. In addition, we also theoretically analyze the loss of GI square-core waveguides with mirrors using a ray-trace simulation tool. Then, in the waveguide based optical link including the optical path conversions via 45-degree mirrors, we show that GI waveguides realize lower total optical loss than conventional step-index (SI) core waveguides. The lower loss in the GI waveguide link is attributed to the tight optical confinement at the core center even after reflection at the mirrors.

  11. Synthesis and optical study of green light emitting polymer coated CdSe/ZnSe core/shell nanocrystals

    SciTech Connect

    Tripathi, S.K.; Sharma, Mamta

    2013-05-15

    Highlights: ► Synthesis of Polymer coated core CdSe and CdSe/ZnSe core/shell NCs. ► From TEM image, the spherical nature of CdSe and CdSe/ZnSe is obtained. ► Exhibiting green band photoemission peak at 541 nm and 549 nm for CdSe core and CdSe/ZnSe core/shell NCs. ► The shell thickness has been calculated by using superposition of quantum confinement energy model. - Abstract: CdSe/ZnSe Core/Shell NCs dispersed in PVA are synthesized by chemical method at room temperature. This is characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), UV/Vis spectra and photoluminescence spectroscopy (PL). TEM image shows the spherical nature of CdSe/ZnSe core/shell NCs. The red shift of absorption and emission peak of CdSe/ZnSe core/shell NCs as compared to CdSe core confirmed the formation of core/shell. The superposition of quantum confinement energy model is used for calculation of thickness of ZnSe shell.

  12. Application of laser light scattering for determination of the border aerosol-air in a specialized physical laboratory setup

    NASA Astrophysics Data System (ADS)

    Damov, K. S.; Iliev, M. T.

    2016-02-01

    The current article examines the application of laser light scattering in a specialized laboratory setup. It is used for determination of the kinematic viscosity and mass density of Aerodispersed Systems formed in Limited Volume (High Concentration Aerosols) by the method of free flow out. The measurement chamber is first filled with the investigated aerosol. After a predetermined delay time the aerosol is allowed to flow out through a calibrated pipe with fixed size located few centimetres above the chamber's bottom. The lowering of the upper border aerosol-air is continuously scanned using a laser beam directed along the axis of the cylindrical chamber. The kinematic viscosity and mass density of the investigated aerosol phase are calculated by formulas obtained by the authors. The suggested application of laser light scattering led to higher accuracy of the determination the position of aerosol-air border, thence the certainty of this method. This improvement allowed the use of computer controlled optoelectronic setting. The use of laser light scattering significantly improves the method for determination of the kinematic viscosity and mass density of Aerodispersed Systems formed in Limited Volume.

  13. Ice core sulfur and methanesulfonic acid (MSA) records from southern Greenland document North American and European air pollution and suggest a decline in regional biogenic sulfur emissions.

    NASA Astrophysics Data System (ADS)

    Pasteris, D. R.; McConnell, J. R.; Burkhart, J. F.; Saltzman, E. S.

    2014-12-01

    Sulfate aerosols have an important cooling effect on the Earth because they scatter sunlight back to space and form cloud condensation nuclei. However, understanding of the atmospheric sulfur cycle is incomplete, leading to uncertainty in the assessment of past, present and future climate forcing. Here we use annually resolved observations of sulfur and methanesulfonic acid (MSA) concentration in an array of precisely dated Southern Greenland ice cores to assess the history of sulfur pollution emitted from North America and Europe and the history of biogenic sulfate aerosol derived from the North Atlantic Ocean over the last 250 years. The ice core sulfur time series is found to closely track sulfur concentrations in North American and European precipitation since records began in 1965, and also closely tracks estimated sulfur emissions since 1850 within the air mass source region as determined by back trajectory analysis. However, a decline to near-preindustrial sulfur concentrations in the ice cores after 1995 that is not so extensive in the source region emissions indicates that there has been a change in sulfur cycling over the last 150 years. The ice core MSA time series shows a decline of 60% since the 1860s, and is well correlated with declining sea ice concentrations around Greenland, suggesting that the phytoplankton source of biogenic sulfur has declined due to a loss of marginal sea ice zone habitat. Incorporating the implied decrease in biogenic sulfur in our analysis improves the match between the ice core sulfur record and the source region emissions throughout the last 150 years, and solves the problem of the recent return to near-preindustrial levels in the Greenland ice. These findings indicate that the transport efficiency of sulfur air pollution has been relatively stable through the industrial era and that biogenic sulfur emissions in the region have declined.

  14. CuS@mSiO2-PEG core-shell nanoparticles as a NIR light responsive drug delivery nanoplatform for efficient chemo-photothermal therapy.

    PubMed

    Liu, Xijian; Ren, Qilong; Fu, Fanfan; Zou, Rujia; Wang, Qian; Xin, Guobing; Xiao, Zhiyin; Huang, Xiaojuan; Liu, Qian; Hu, Junqing

    2015-06-14

    We report a facile and low-cost approach to design a difunctional nanoplatform (CuS@mSiO2-PEG) as a near-infrared (NIR) light responsive drug delivery system for efficient chemo-photothermal therapy. The nanoplatform demonstrated good biocompatibility and colloidal stability, as well as high loading capacity for the anticancer drug (26.5 wt% for doxorubicin (DOX)). The CuS nanocrystals (core) within these CuS@mSiO2-PEG core-shell nanoparticles can effectively absorb and convert NIR light to fatal heat under NIR light irradiation for photothermal therapy, and the release of DOX from the mesoporous silica (shell) can be triggered by pH and NIR light for chemotherapy. When the CuS@mSiO2-PEG/DOX nanocomposites were irradiated by 980 nm light, both chemotherapy and photothermal therapy were simultaneously driven, resulting in a synergistic effect for killing cancer cells. Importantly, compared with chemotherapy or photothermal treatment alone, the combined therapy significantly improved the therapeutic efficacy. PMID:25970690

  15. CuS@mSiO2-PEG core-shell nanoparticles as a NIR light responsive drug delivery nanoplatform for efficient chemo-photothermal therapy.

    PubMed

    Liu, Xijian; Ren, Qilong; Fu, Fanfan; Zou, Rujia; Wang, Qian; Xin, Guobing; Xiao, Zhiyin; Huang, Xiaojuan; Liu, Qian; Hu, Junqing

    2015-06-14

    We report a facile and low-cost approach to design a difunctional nanoplatform (CuS@mSiO2-PEG) as a near-infrared (NIR) light responsive drug delivery system for efficient chemo-photothermal therapy. The nanoplatform demonstrated good biocompatibility and colloidal stability, as well as high loading capacity for the anticancer drug (26.5 wt% for doxorubicin (DOX)). The CuS nanocrystals (core) within these CuS@mSiO2-PEG core-shell nanoparticles can effectively absorb and convert NIR light to fatal heat under NIR light irradiation for photothermal therapy, and the release of DOX from the mesoporous silica (shell) can be triggered by pH and NIR light for chemotherapy. When the CuS@mSiO2-PEG/DOX nanocomposites were irradiated by 980 nm light, both chemotherapy and photothermal therapy were simultaneously driven, resulting in a synergistic effect for killing cancer cells. Importantly, compared with chemotherapy or photothermal treatment alone, the combined therapy significantly improved the therapeutic efficacy.

  16. Correction of the spectral calibration of the Joint European Torus core light detecting and ranging Thomson scattering diagnostic using ray tracing

    SciTech Connect

    Hawke, J.; Scannell, R.; Maslov, M.; Migozzi, J. B.; Collaboration: JET-EFDA Contributors

    2013-10-15

    This work isolated the cause of the observed discrepancy between the electron temperature (T{sub e}) measurements before and after the JET Core LIDAR Thomson Scattering (TS) diagnostic was upgraded. In the upgrade process, stray light filters positioned just before the detectors were removed from the system. Modelling showed that the shift imposed on the stray light filters transmission functions due to the variations in the incidence angles of the collected photons impacted plasma measurements. To correct for this identified source of error, correction factors were developed using ray tracing models for the calibration and operational states of the diagnostic. The application of these correction factors resulted in an increase in the observed T{sub e}, resulting in the partial if not complete removal of the observed discrepancy in the measured T{sub e} between the JET core LIDAR TS diagnostic, High Resolution Thomson Scattering, and the Electron Cyclotron Emission diagnostics.

  17. Correction of the spectral calibration of the Joint European Torus core light detecting and ranging Thomson scattering diagnostic using ray tracing.

    PubMed

    Hawke, J; Scannell, R; Maslov, M; Migozzi, J B

    2013-10-01

    This work isolated the cause of the observed discrepancy between the electron temperature (T(e)) measurements before and after the JET Core LIDAR Thomson Scattering (TS) diagnostic was upgraded. In the upgrade process, stray light filters positioned just before the detectors were removed from the system. Modelling showed that the shift imposed on the stray light filters transmission functions due to the variations in the incidence angles of the collected photons impacted plasma measurements. To correct for this identified source of error, correction factors were developed using ray tracing models for the calibration and operational states of the diagnostic. The application of these correction factors resulted in an increase in the observed T(e), resulting in the partial if not complete removal of the observed discrepancy in the measured T(e) between the JET core LIDAR TS diagnostic, High Resolution Thomson Scattering, and the Electron Cyclotron Emission diagnostics.

  18. Ice core evidence of rapid air temperature increases since 1960 in alpine areas of the Wind River Range, Wyoming, United States

    USGS Publications Warehouse

    Naftz, D.L.; Susong, D.D.; Schuster, P.F.; Cecil, L.D.; Dettinger, M.D.; Michel, R.L.; Kendall, C.

    2002-01-01

    Site-specific transfer functions relating delta oxygen 18 (??18O) values in snow to the average air temperature (TA) during storms on Upper Fremont Glacier (UFG) were used in conjunction with ??18O records from UFG ice cores to reconstruct long-term trends in air temperature from alpine areas in the Wind River Range, Wyoming. Transfer functions were determined by using data collected from four seasonal snowpacks (1989-1990, 1997-1998, 1998-1999, and 1999-2000). The timing and amount of each storm was determined from an automated snowpack telemetry (SNOTEL) site, 22 km northeast of UFG, and ???1060 m in elevation below UFG. Statistically significant and positive correlations between ??18O values in the snow and TA were consistently found in three of the four seasonal snowpacks. The snowpack with the poor correlation was deposited in 1997-1998 during the 1997-1998 El Nin??o Southern Oscillation (ENSO). An ultrasonic snow-depth sensor installed on UFG provided valuable insights into site-specific storms and postdepositional processes that occur on UFG. The timing of storms recorded at the UFG and Cold Springs SNOTEL sites were similar; however, selected storms did not correlate. Snow from storms occurring after mid-October and followed by high winds was most susceptible to redeposition of snow. This removal of lower temperature snowfall could potentially bias the ??18O values preserved in ice core records to environmental conditions reflecting higher air temperatures and lower wind speeds. Transfer functions derived from seasonal snow cover on UFG were used to reconstruct TA values from ??18O values determined from two ice cores collected from UFG. Reconstructed air temperatures from the ice core data indicate an increase in TA of ???3.5??C from the mid-1960s to the early 1990s in the alpine areas of northwestern Wyoming. Reconstructed TA from the ice core records between the end of the Little Ice Age (LIA), mid-1800s, and the early 1990s indicate a TA increase of

  19. High efficiency, full-color AlInGaN quaternary nanowire light emitting diodes with spontaneous core-shell structures on Si

    NASA Astrophysics Data System (ADS)

    Wang, Renjie; Liu, Xuedong; Shih, Ishiang; Mi, Zetian

    2015-06-01

    We have developed AlInGaN quaternary core-shell nanowire heterostructures on Si substrate, wherein an In-rich core and an Al-rich shell were spontaneously formed during the epitaxial growth process. By varying the growth conditions, the emission wavelengths can be tuned from ˜430 nm to ˜630 nm. Such core-shell structures can largely suppress nonradiative surface recombination, leading to a significant enhancement of carrier lifetime from ˜0.2 ns to ˜2 ns. The resulting nanowire light emitting diodes can exhibit an output power exceeding 30 mW for a ˜1 × 1 mm2 non-packaged device at a current density of 100 A/cm2.

  20. A Compact Fiber Inclinometer Using a Thin-Core Fiber with Incorporated an Air-Gap Microcavity Fiber Interferometer

    PubMed Central

    Li, Jiacheng; Qiao, Xueguang; Rong, Qiangzhou; Sun, An

    2016-01-01

    A compact fiber-optic inclinometer is proposed and experimentally demonstrated based on a Fabry-Perot interference (FFPI). The sensing head consists of a short segment of thin-core fiber (TCF) following with a piece of hollow-core fiber (HCF). High-order cladding modes have been excited because of core diameter mismatch. A clear interference spectrum has been obtained as the consequence of interference among the reflected core modes and cladding modes. Fringe contrast of the interference spectrum is highly sensitive to fiber bending with direction independence, and good linearity has been observed during the bending range from 1° to 3° with a sensitivity of 2.71 dB/deg. PMID:26771614

  1. A Compact Fiber Inclinometer Using a Thin-Core Fiber with Incorporated an Air-Gap Microcavity Fiber Interferometer.

    PubMed

    Li, Jiacheng; Qiao, Xueguang; Rong, Qiangzhou; Sun, An

    2016-01-01

    A compact fiber-optic inclinometer is proposed and experimentally demonstrated based on a Fabry-Perot interference (FFPI). The sensing head consists of a short segment of thin-core fiber (TCF) following with a piece of hollow-core fiber (HCF). High-order cladding modes have been excited because of core diameter mismatch. A clear interference spectrum has been obtained as the consequence of interference among the reflected core modes and cladding modes. Fringe contrast of the interference spectrum is highly sensitive to fiber bending with direction independence, and good linearity has been observed during the bending range from 1° to 3° with a sensitivity of 2.71 dB/deg. PMID:26771614

  2. Design of single-winding energy-storage reactors for dc-to-dc converters using air-gapped magnetic-core structures

    NASA Technical Reports Server (NTRS)

    Ohri, A. K.; Wilson, T. G.; Owen, H. A., Jr.

    1977-01-01

    A procedure is presented for designing air-gapped energy-storage reactors for nine different dc-to-dc converters resulting from combinations of three single-winding power stages for voltage stepup, current stepup and voltage stepup/current stepup and three controllers with control laws that impose constant-frequency, constant transistor on-time and constant transistor off-time operation. The analysis, based on the energy-transfer requirement of the reactor, leads to a simple relationship for the required minimum volume of the air gap. Determination of this minimum air gap volume then permits the selection of either an air gap or a cross-sectional core area. Having picked one parameter, the minimum value of the other immediately leads to selection of the physical magnetic structure. Other analytically derived equations are used to obtain values for the required turns, the inductance, and the maximum rms winding current. The design procedure is applicable to a wide range of magnetic material characteristics and physical configurations for the air-gapped magnetic structure.

  3. Angularly symmetric splitting of a light beam upon reflection and refraction at an air-dielectric plane boundary: comment.

    PubMed

    Andersen, Torben B

    2016-05-01

    In a recent paper, conditions for achieving equal and opposite angular deflections of a light beam by reflection and refraction at an interface between air and a dielectric were determined [J. Opt. Soc. Am. A32, 2436 (2015)JOAOD60740-323210.1364/JOSAA.32.002436]. The paper gives plots of angles of incidence and refraction as a function of the prism refractive index as well as plots of reflectances and incident linear-polarization azimuth angles as functions of the refractive index. We show here that it is possible to express these quantities as simple algebraic functions of the refractive index.

  4. One-step synthesis of novel PANI-Fe3O4@ZnO core-shell microspheres: An efficient photocatalyst under visible light irradiation

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaoyuan; Wu, Jianning; Meng, Guihua; Guo, Xuhong; Liu, Chang; Liu, Zhiyong

    2016-03-01

    For the first time, novel multifunctional superparamagnetic PANI-Fe3O4@ZnO core-shell composite photocatalysts with different PANI: ZnO ratios were synthesized by Pickering emulsion route in one step in the presence of ZnO nanoparticles. PANI-Fe3O4@ZnO core-shell microspheres consist of PANI core which embedded with Fe3O4-OA (oleic acid modified Fe3O4) nanoparticles and tunable ZnO shell thickness. The resulting samples were thoroughly studied by using X-ray diffraction (XRD), X-ray photoelectron spectra (XPS), transmission electron microscopy (TEM), scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDS). The catalytic activity of the as-prepared PANI-Fe3O4@ZnO core-shell microspheres is investigated by the degradation of MB under visible light irradiation. As expected, the as prepared PANI-Fe3O4@ZnO photocatalysts exhibit highly enhanced photocatalytic activities in the degradation of MB under visible light irradiation owing to fast separation of photo-generated electron-hole pairs. Significantly, the PANI-Fe3O4@ZnO catalysts can be separated from the reaction media by applying an external magnet, and can be reused for seven cycles without change in stability and degradation efficiency.

  5. Angularly symmetric splitting of a light beam upon reflection and refraction at an air-dielectric plane boundary.

    PubMed

    Azzam, R M A

    2015-12-01

    Conditions for achieving equal and opposite angular deflections of a light beam by reflection and refraction at an air-dielectric boundary are determined. Such angularly symmetric beam splitting (ASBS) is possible only if the angle of incidence is >60° by exactly one third of the angle of refraction. This simple law, plus Snell's law, leads to several analytical results that clarify all aspects of this phenomenon. In particular, it is shown that the intensities of the two symmetrically deflected beams can be equalized by proper choice of the prism refractive index and the azimuth of incident linearly polarized light. ASBS enables a geometrically attractive layout of optical systems that employ multiple prism beam splitters.

  6. Highly bright yellow-green-emitting CuInS₂ colloidal quantum dots with core/shell/shell architecture for white light-emitting diodes.

    PubMed

    Park, Sang Hyun; Hong, Ara; Kim, Jong-Hoon; Yang, Heesun; Lee, Kwangyeol; Jang, Ho Seong

    2015-04-01

    In this study, we report bright yellow-green-emitting CuInS2 (CIS)-based quantum dots (QDs) and two-band white light-emitting diodes (LEDs) using them. To achieve high quantum efficiency (QE) of yellow-green-emitting CIS QDs, core/shell/shell strategy was introduced to high quality CIS cores (QE = 31.7%) synthesized by using metal-oleate precursors and 1-dodecanethiol. The CIS/ZnS/ZnS QDs showed a high QE of 80.0% and a peak wavelength of 559 nm under the excitation of 450 nm, which is well matched with dominant wavelength of blue LEDs. The formation of core/shell/shell structure was confirmed by X-ray diffraction, transmission electron microscopy, and inductively coupled plasma-optical emission spectroscopy analyses. Intense and broad yellow-green emission band of the CIS/ZnS/ZnS is beneficial for bright two-band white light. When the CIS/ZnS/ZnS was coated on the blue LEDs, the fabricated white LED showed bright natural white light (luminous efficacy (η(L)) = 80.3 lm·W(-1), color rendering index (R(a)) = 73, correlated color temperature (T(c)) = 6140 K). The QD-white LED package showed a high light conversion efficiency of 72.6%. In addition, the CIS/ZnS/ZnS-converted white LED showed relatively stable white light against the variation of forward bias currents of 20-150 mA [color coordinates (x, y) = (0.3320-0.3207, 0.2997-0.2867), R(a) = 70-72, T(c) = 5497-6375 K]. PMID:25757746

  7. Gold-Quantum Dot Core-Satellite Assemblies for Lighting Up MicroRNA In Vitro and In Vivo.

    PubMed

    Zhao, Xueli; Xu, Liguang; Sun, Maozhong; Ma, Wei; Wu, Xiaoling; Kuang, Hua; Wang, Libing; Xu, Chuanlai

    2016-09-01

    A high yield DNA-driven gold-quantum dot core-satellite is developed for miRNA detection in vitro and vivo. In the presence of the target miRNA, the DNA hairpin between core and satellite is ruined, resulting in the recovery of fluorescence. The limit of detection for miRNA-21 detection in living cells reaches 296 copies per cell. PMID:26849492

  8. Feasibility report: Operation of light air cushion vehicle at McMurdo Sound, Antarctica

    NASA Astrophysics Data System (ADS)

    Dibbern, J. S.

    1987-02-01

    This report explores the viability of the use of an air cushion vehicle (ACV) or hovercraft to perform logistic and scientific support in the area of McMurdo Station, Antarctica. After a review of personnel assets and facilities at McMurdo Station to support the ACV plus a reconnaissance of the five major routes selected, it appears that an air cushion vehicle in the 1 to 1 1/2 ton payload class would be of significant value to support operations. It would reduce transit times for surface vehicle traverses on the routes selected and reduce requirements for expenditure of helicopter flight time in others. Of major significance is the ability to handle passenger/shuttle requirements between the Scott Base transition and Williams Field Skiway. Use of the ACV for high frequency passenger operations would help preserve the snow road for cargo operations during periods of road deterioration.

  9. Defect-mediated of Cu@TiO2 core-shell nanoparticles with oxygen vacancies for photocatalytic degradation 2,4-DCP under visible light irradiation

    NASA Astrophysics Data System (ADS)

    Wang, Zhen; Zang, Ling; Fan, Xiaoyun; Jia, Hanzhong; Li, Li; Deng, Wenye; Wang, Chuanyi

    2015-12-01

    Cu @TiO2 core-shell nanoparticles with different mass ratios of Cu to TiO2 were facilely synthesized via wet chemical approaches, and were characterized by transmission electron microscopy, scanning electron microscopy, UV-vis diffuse reflection absorption spectroscopy, X-ray photoelectron spectroscopy and electron paramagnetic resonance. The photocatalytic efficiency of Cu@TiO2 nanoparticles was evaluated by degradation of 2,4-dichlorophenol, a typical persistent organic pollutant, under visible light irradiation. The results show that the oxygen vacancy creation obviously enhances the visible-light absorption of TiO2. Meanwhile, the Cu nanoparticle incorporation into the TiO2 can effectively improve charge-separation efficiency of Cu@TiO2 under visible-light irradiation, thereby enhancing the photoactivity.

  10. Core-Shell Structural CdS@SnO₂ Nanorods with Excellent Visible-Light Photocatalytic Activity for the Selective Oxidation of Benzyl Alcohol to Benzaldehyde.

    PubMed

    Liu, Ya; Zhang, Ping; Tian, Baozhu; Zhang, Jinlong

    2015-07-01

    Core-shell structural CdS@SnO2 nanorods (NRs) were fabricated by synthesizing SnO2 nanoparticles with a solvent-assisted interfacial reaction and further anchoring them on the surface of CdS NRs under ultrasonic stirring. The morphology, composition, and microstructures of the obtained samples were characterized by field-emission scanning electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and nitrogen adsorption-desorption. It was found that SnO2 nanoparticles can be tightly anchored on the surface of CdS NRs, and the thickness of SnO2 shells can be conveniently adjusted by simply changing the addition amount of SnO2 quantum dots. UV-vis diffuse reflectance spectrum indicated that SnO2 shell layer also can enhance the visible light absorption of CdS NRs to a certain extent. The results of transient photocurrents and photoluminescence spectra revealed that the core-shell structure can effectively promote the separation rate of electron-hole pairs and prolong the lifetime of electrons. Compared with the single CdS NRs, the core-shell structural CdS@SnO2 exhibited a remarkably enhanced photocatalytic activity for selective oxidation of benzyl alcohol (BA) to benzaldehyde (BAD) under visible light irradiation, attributed to the more efficient separation of electrons and holes, improved surface area, and enhanced visible light absorption of core-shell structure. The radical scavenging experiments proved that in acetonitrile solution, ·O2- and holes are the main reactive species responsible for BA to BAD transformation, and the lack of ·OH radicals is favorable to obtaining high reaction selectivity.

  11. Brief light stimulation during the mouse nocturnal activity phase simultaneously induces a decline in core temperature and locomotor activity followed by EEG-determined sleep

    PubMed Central

    Studholme, Keith M.; Gompf, Heinrich S.

    2013-01-01

    Light exerts a variety of effects on mammals. Unexpectedly, one of these effects is the cessation of nocturnal locomotion and the induction of behavioral sleep (photosomnolence). Here, we extend the initial observations in several ways, including the fundamental demonstration that core body temperature (Tc) drops substantially (about 1.5°C) in response to the light stimulation at CT15 or CT18 in a manner suggesting that the change is a direct response to light rather than simply a result of the locomotor suppression. The results show that 1) the decline of locomotion and Tc begin soon after nocturnal light stimulation; 2) the variability in the magnitude and onset of light-induced locomotor suppression is very large, whereas the variability in Tc is very small; 3) Tc recovers from the light-induced decline in advance of the recovery of locomotion; 4) under entrained and freerunning conditions, the daily late afternoon Tc increase occurs in advance of the corresponding increase in wheel running; and 5) toward the end of the subjective night, the nocturnally elevated Tc persists longer than does locomotor activity. Finally, EEG measurements confirm light-induced sleep and, when Tc or locomotion was measured, show their temporal association with sleep onset. Both EEG- and immobility-based sleep detection methods confirm rapid induction of light-induced sleep. The similarities between light-induced loss of locomotion and drop in Tc suggest a common cause for parallel responses. The photosomnolence response may be contingent upon both the absence of locomotion and a simultaneous low Tc. PMID:23364525

  12. Sub-nanosecond time resolved light emission study for diffuse discharges in air under steep high voltage pulses

    NASA Astrophysics Data System (ADS)

    Tardiveau, P.; Magne, L.; Marode, E.; Ouaras, K.; Jeanney, P.; Bournonville, B.

    2016-10-01

    Pin-to-plane discharges in centimetre air gaps and standard conditions of pressure and temperature are generated under very high positive nanosecond scale voltage pulses. The experimental study is based on recordings of sub-nanosecond time resolved and Abel-processed light emission profiles and their complete correlation to electrical current waveforms. The effects of the voltage pulse features (amplitude between 20 and 90 kV, rise time between 2 and 5.2 ns, and time rate between 4 and 40 kV · ns‑1) and the electrode configuration (gap distance between 10 and 30 mm, pin radius between 10 and 200 µm, copper, molybdenum or tungsten pin material) are described. A three time period development can be found: a glow-like structure with monotonic light profiles during the first 1.5 ns whose size depends on time voltage rate, a shell-like structure with bimodal profiles whose duration and extension in space depends on rise time, and either diffuse or multi-channel regime for the connection to the cathode plane according to gap distance. The transition of the light from monotonic to bimodal patterns reveals the relative effects and dynamics of streamer space charge and external laplacian field. A classical 2D-fluid model for streamer propagation has been used and adapted for very high and steep voltage pulses. It shows the formation of a strong space charge (streamer) very close to the pin, but also a continuity of emission between the pin and the streamer, and electric fields higher than the critical ionization field (28 kV · cm‑1 in air) almost in the whole gap and very early in the discharge propagation.

  13. Phase and Size Control of Core-Shell Upconversion Nanocrystals Light up Deep Dual Luminescence Imaging and CT In Vivo.

    PubMed

    Kang, Ning; Liu, Yu; Zhou, Yaming; Wang, Dong; Chen, Chuan; Ye, Shefang; Nie, Liming; Ren, Lei

    2016-06-01

    Upconversion nanocrystals (UCNCs) have recently been explored as optical imaging nanoprobes. However, conventional β-NaLuF4 (-) based UCNCs often suffer from large particle size and weak upconversion luminescence (UCL) intensity, leading to poor biocompatibility and low detection sensitivity. Here, a novel strategy for controlling the crystalline phase and size of UCNCs has been developed by doping of yttrium ions, resulting in particle size reduction and phase transition. The total UCL intensity of prepared core-shell UCNCs is significantly enhanced up to ≈4.9 and ≈17.4 times after Tm(3+) and Er(3+) doping than that of core UCNCs, offering deeper tissue UCL imaging with a depth of 8 mm in vivo. Moreover, the CT signal of core-shell UCNCs is ≈1.5 and ≈3.5 times brighter than that of core UCNCs and commercial ioversol agent because of increasing contents of Lu(3+) doped in UCNCs. The synthesized core-shell UCNCs hold a great promise in deep UCL and CT dual-modality imaging in vitro and in vivo. PMID:26990395

  14. Technologies for Maintaining Animals in Space: Lighting, Air Quality, Noise, Food and Water

    NASA Technical Reports Server (NTRS)

    Winget, C. M.; Skidmore, M. G.; Holley, D. C.; Dalton, Bonnie P. (Technical Monitor)

    1995-01-01

    In the terrestrial environment multiple time cues exist. Zeitgebers have been identified and studied for their ability to convey temporal information to various physiological systems, In the microgravity experiment it is necessary to define time cues within the flight hardware prior to flight. During flight if changes in the Circadian System (e.g., mean, phase angle, period) occur this would indicate that the gravity vector is important relative to biological timing. This presentation is concerned with the environmental parameters to support rodent experiments in microgravity. The Animal Enclosure Module (AEM) provides solid food bars and water via lixits ad libitum. Flight animals (Sprague-Dawley rats, 60 - 300g) when compared to ground controls show similar growth (mean growth per day, g +/- SD; flight 5.4 +/- 2.0, ground 5.9 +/- 2.1). Current AEMs use incandescent lighting (approx. 5 Lux). Light emitting diode (LED) arrays are being developed that provide a similar light environment as cool-white fluorescent sources (40 Lux). In ground based tests (12L:12D), these arrays show normal circadian entrainment (Tau = 24.0) with respect to the behavioral responses. measured (drinking, eating, gross locomotor activity). A newly developed ultra high efficiency filter system can entrap all feces, urine and odors from 6 rats for 24 days. Maximum sound level exposure limits (per octave band 22 Hz - 179 kHz) have been established. The AEM will effectively support animal experiments in microgravity.

  15. Technologies For Maintaining Animals In Space: Lighting, Air Quality, Noise, Food And Water

    NASA Technical Reports Server (NTRS)

    Winget, C. M.; Skidmore, M. G.; Holley, D. C.; Dalton, Bonnie P. (Technical Monitor)

    1995-01-01

    In the terrestrial environment multiple time cues exist. Zeitgebers have been identified and studied for their ability to convey temporal information to various physiological systems. In the microgravity experiment it is necessary to define time cues within the flight hardware prior to flight. During flight if changes in the Circadian System (e.g., mean, phase angle, period) occur this would indicate that the gravity vector is important relative to biological timing. This presentation is concerned with the environmental parameter: to support rodent experiments in microgravity. The Animal Enclosure Module (AEM) provides solid food bars and water via lixits and ad libitum. Flight animals (Sprague-Dawley rats, 60 - 300g) when compared to ground controls show similar growth (mean growth per day g, plus or minus SD; flight 5.4 plus or minus 2.0, ground 5.9 plus or minus 2.1). Current AEMs use incandescent lighting (approx. 5 Lux). Light emitting diode (LED) arrays are being developed that provide a similar light environment as cool-white fluorescent sources (40 Lux). In ground based tests (12L:12D), these arrays show normal circadian entrainment (Tau = 24.0) with respect to the behavioral responses, measured (drinking, eating, gross locomotor activity). A newly developed ultra high efficiency filter system can entrap all feces, urine and odors from 6 rats for 24 days. Maximum sound level exposure limits (per octave band 22 Hz - 179 kHz) have been established. The AEM will effectively support animal experiments in microgravity.

  16. Ultrathin TiO2 layer coated-CdS spheres core-shell nanocomposite with enhanced visible-light photoactivity.

    PubMed

    Chen, Zhang; Xu, Yi-Jun

    2013-12-26

    Development of various strategies for controllable fabrication of core-shell nanocomposites (CSNs) with highly active photocatalytic performance has been attracting ever-increasing research attention. In particular, control of the ultrathin layer TiO2 shell in constructing CSNs in an aqueous phase is a significant but technologically challenging issue. Here, this paper demonstrates the interface assembly synthesis of CdS nanospheres@TiO2 core-shell photocatalyst via the electrostatic interaction of negatively charged water-stable titania precursor with positively charged CdS nanospheres (CdS NSPs), followed by the formation of the ultrathin-layer TiO2 shell through a facile refluxing process in aqueous phase. The as-formed CdS NSPs@TiO2 core-shell nanohybrid exhibits a high visible-light-driven photoactivity for selective transformation and reduction of heavy metal ions. The ultrathin TiO2 layer coated on CdS NSPs results in excellent light transmission property, enhanced adsorption capacity, and improved transfer of charge carriers and lifespan of photoinduced electron-hole pairs, which would prominently contribute to the significant photoactivity enhancement. It is anticipated that this facile aqueous-phase synthesis strategy could be extended to design a variety of more efficient CSN photocatalysts with controllable morphology toward target applications in diverse photoredox processes.

  17. Ultrathin TiO2 layer coated-CdS spheres core-shell nanocomposite with enhanced visible-light photoactivity.

    PubMed

    Chen, Zhang; Xu, Yi-Jun

    2013-12-26

    Development of various strategies for controllable fabrication of core-shell nanocomposites (CSNs) with highly active photocatalytic performance has been attracting ever-increasing research attention. In particular, control of the ultrathin layer TiO2 shell in constructing CSNs in an aqueous phase is a significant but technologically challenging issue. Here, this paper demonstrates the interface assembly synthesis of CdS nanospheres@TiO2 core-shell photocatalyst via the electrostatic interaction of negatively charged water-stable titania precursor with positively charged CdS nanospheres (CdS NSPs), followed by the formation of the ultrathin-layer TiO2 shell through a facile refluxing process in aqueous phase. The as-formed CdS NSPs@TiO2 core-shell nanohybrid exhibits a high visible-light-driven photoactivity for selective transformation and reduction of heavy metal ions. The ultrathin TiO2 layer coated on CdS NSPs results in excellent light transmission property, enhanced adsorption capacity, and improved transfer of charge carriers and lifespan of photoinduced electron-hole pairs, which would prominently contribute to the significant photoactivity enhancement. It is anticipated that this facile aqueous-phase synthesis strategy could be extended to design a variety of more efficient CSN photocatalysts with controllable morphology toward target applications in diverse photoredox processes. PMID:24245797

  18. Results from Geothermal Logging, Air and Core-Water Chemistry Sampling, Air Injection Testing and Tracer Testing in the Northern Ghost Dance Fault, YUCCA Mountain, Nevada, November 1996 to August 1998

    SciTech Connect

    Lecain, G.D.; Anna, L.O.; Fahy, M.F.

    1998-08-01

    Geothermal logging, air and core-water chemistry sampling, air-injection testing, and tracer testing were done in the northern Ghost Dance Fault at Yucca Mountain, Nevada, from November 1996 to August 1998. The study was done by the U.S. Geological Survey, in cooperation with the U.S. Department of Energy. The fault-testing drill room and test boreholes were located in the crystal-poor, middle nonlithophysal zone of the Topopah Spring Tuff, a tuff deposit of Miocene age. The drill room is located off the Yucca Mountain underground Exploratory Studies Facility at about 230 meters below ground surface. Borehole geothermal logging identified a temperature decrease of 0.1 degree Celsius near the Ghost Dance Fault. The temperature decrease could indicate movement of cooler air or water, or both, down the fault, or it may be due to drilling-induced evaporative or adiabatic cooling. In-situ pneumatic pressure monitoring indicated that barometric pressure changes were transmitted from the ground surface to depth through the Ghost Dance Fault. Values of carbon dioxide and delta carbon-13 from gas samples indicated that air from the underground drill room had penetrated the tuff, supporting the concept of a well-developed fracture system. Uncorrected carbon-14-age estimates from gas samples ranged from 2,400 to 4,500 years. Tritium levels in borehole core water indicated that the fault may have been a conduit for the transport of water from the ground surface to depth during the last 100 years.

  19. The Effects of Projected Future Demand Including Very Light Jet Air-Taxi Operations on U.S. National Airspace System Delays as a Function of Next Generation Air Transportation System Airspace Capacity

    NASA Technical Reports Server (NTRS)

    Smith, Jerry; Viken, Jeff; Dollyhigh, Samuel; Trani, Antonio; Baik, Hojong; Hinze, Nicholas; Ashiabor, Senanu

    2007-01-01

    This paper presents the results from a study which investigates the potential effects of the growth in air traffic demand including projected Very Light Jet (VLJ) air-taxi operations adding to delays experienced by commercial passenger air transportation in the year 2025. The geographic region studied is the contiguous United States (U.S.) of America, although international air traffic to and from the U.S. is included. The main focus of this paper is to determine how much air traffic growth, including VLJ air-taxi operations will add to enroute airspace congestion and determine what additional airspace capacity will be needed to accommodate the expected demand. Terminal airspace is not modeled and increased airport capacity is assumed.

  20. Experimental and theoretical analysis of transport properties of core-shell wire light emitting diodes probed by electron beam induced current microscopy.

    PubMed

    Lavenus, P; Messanvi, A; Rigutti, L; De Luna Bugallo, A; Zhang, H; Bayle, F; Julien, F H; Eymery, J; Durand, C; Tchernycheva, M

    2014-06-27

    We report a systematic experimental and theoretical investigation of core-shell InGaN/GaN single wire light-emitting diodes (LEDs) using electron beam induced current (EBIC) microscopy. The wires were grown by catalyst-free MOVPE and processed into single wire LEDs using electron beam lithography on dispersed wires. The influence of the acceleration voltage and of the applied bias on the EBIC maps was investigated. We show that the EBIC maps provide information both on the minority carrier effects (i.e. on the local p-n junction collection efficiency) and on the majority carrier effects (i.e. the transport efficiency from the excited region toward the contacts). Because of a finite core and shell resistance a non-negligible current redistribution into the p-n junction takes place during the majority carrier transport. A theoretical model for transport in a core-shell wire is developed, allowing to explain the dependence of the EBIC profiles on the experimental parameters (the electron beam acceleration voltage and the bias applied on the device) and on the structural parameters of the wire (core and shell resistance, shunt resistance, etc). Comparison between simulated and experimental profiles provides valuable information concerning the structure inhomogeneities and gives insight into the wire electrical parameters.

  1. Emission Characteristics of InGaN/GaN Core-Shell Nanorods Embedded in a 3D Light-Emitting Diode.

    PubMed

    Jung, Byung Oh; Bae, Si-Young; Lee, Seunga; Kim, Sang Yun; Lee, Jeong Yong; Honda, Yoshio; Amano, Hiroshi

    2016-12-01

    We report the selective-area growth of a gallium nitride (GaN)-nanorod-based InGaN/GaN multiple-quantum-well (MQW) core-shell structure embedded in a three-dimensional (3D) light-emitting diode (LED) grown by metalorganic chemical vapor deposition (MOCVD) and its optical analysis. High-resolution transmission electron microscopy (HR-TEM) observation revealed the high quality of the GaN nanorods and the position dependence of the structural properties of the InGaN/GaN MQWs on multiple facets. The excitation and temperature dependences of photoluminescence (PL) revealed the m-plane emission behaviors of the InGaN/GaN core-shell nanorods. The electroluminescence (EL) of the InGaN/GaN core-shell-nanorod-embedded 3D LED changed color from green to blue with increasing injection current. This phenomenon was mainly due to the energy gradient and deep localization of the indium in the selectively grown InGaN/GaN core-shell MQWs on the 3D architecture. PMID:27102904

  2. Emission Characteristics of InGaN/GaN Core-Shell Nanorods Embedded in a 3D Light-Emitting Diode.

    PubMed

    Jung, Byung Oh; Bae, Si-Young; Lee, Seunga; Kim, Sang Yun; Lee, Jeong Yong; Honda, Yoshio; Amano, Hiroshi

    2016-12-01

    We report the selective-area growth of a gallium nitride (GaN)-nanorod-based InGaN/GaN multiple-quantum-well (MQW) core-shell structure embedded in a three-dimensional (3D) light-emitting diode (LED) grown by metalorganic chemical vapor deposition (MOCVD) and its optical analysis. High-resolution transmission electron microscopy (HR-TEM) observation revealed the high quality of the GaN nanorods and the position dependence of the structural properties of the InGaN/GaN MQWs on multiple facets. The excitation and temperature dependences of photoluminescence (PL) revealed the m-plane emission behaviors of the InGaN/GaN core-shell nanorods. The electroluminescence (EL) of the InGaN/GaN core-shell-nanorod-embedded 3D LED changed color from green to blue with increasing injection current. This phenomenon was mainly due to the energy gradient and deep localization of the indium in the selectively grown InGaN/GaN core-shell MQWs on the 3D architecture.

  3. Emission Characteristics of InGaN/GaN Core-Shell Nanorods Embedded in a 3D Light-Emitting Diode

    NASA Astrophysics Data System (ADS)

    Jung, Byung Oh; Bae, Si-Young; Lee, Seunga; Kim, Sang Yun; Lee, Jeong Yong; Honda, Yoshio; Amano, Hiroshi

    2016-04-01

    We report the selective-area growth of a gallium nitride (GaN)-nanorod-based InGaN/GaN multiple-quantum-well (MQW) core-shell structure embedded in a three-dimensional (3D) light-emitting diode (LED) grown by metalorganic chemical vapor deposition (MOCVD) and its optical analysis. High-resolution transmission electron microscopy (HR-TEM) observation revealed the high quality of the GaN nanorods and the position dependence of the structural properties of the InGaN/GaN MQWs on multiple facets. The excitation and temperature dependences of photoluminescence (PL) revealed the m-plane emission behaviors of the InGaN/GaN core-shell nanorods. The electroluminescence (EL) of the InGaN/GaN core-shell-nanorod-embedded 3D LED changed color from green to blue with increasing injection current. This phenomenon was mainly due to the energy gradient and deep localization of the indium in the selectively grown InGaN/GaN core-shell MQWs on the 3D architecture.

  4. Design study of an air pump and integral lift engine ALF-504 using the Lycoming 502 core

    NASA Technical Reports Server (NTRS)

    Rauch, D.

    1972-01-01

    Design studies were conducted for an integral lift fan engine utilizing the Lycoming 502 fan core with the final MQT power turbine. The fan is designed for a 12.5 bypass ratio and 1.25:1 pressure ratio, and provides supercharging for the core. Maximum sea level static thrust is 8370 pounds with a specific fuel consumption of 0.302 lb/hr-lb. The dry engine weight without starter is 1419 pounds including full-length duct and sound-attenuating rings. The engine envelope including duct treatment but not localized accessory protrusion is 53.25 inches in diameter and 59.2 inches long from exhaust nozzle exit to fan inlet flange. Detailed analyses include fan aerodynamics, fan and reduction gear mechanical design, fan dynamic analysis, engine noise analysis, engine performance, and weight analysis.

  5. In situ crystallization for fabrication of a core-satellite structured BiOBr-CdS heterostructure with excellent visible-light-responsive photoreactivity

    NASA Astrophysics Data System (ADS)

    Guo, Yuxi; Huang, Hongwei; He, Ying; Tian, Na; Zhang, Tierui; Chu, Paul K.; An, Qi; Zhang, Yihe

    2015-07-01

    We demonstrate the fabrication of a core-satellite structured BiOBr-CdS photocatalyst with highly efficient photocatalytic reactivity via a facile in situ crystallization approach at room temperature. The transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HR-TEM) results reveal that the BiOBr flakes are surrounded by CdS particles. The coverage of the satellites on the surface of the BiOBr nanosheets could be controlled by changing the content of the CdS, which contributes to the enhanced level of photocatalytic performance. The UV-vis diffuse reflection spectra demonstrate that the visible light absorption of the BiOBr-CdS photocatalyst is also enhanced by the CdS loaded. The excellent structural and spectral properties endow the BiOBr-CdS heterojunctions with improved photocatalytic performance pertaining to bisphenol A (BPA) degradation and photocurrent generation. Under visible light irradiation, the optimum photocatalytic activity of BiOBr-CdS at a molar ratio of 1 : 5 (CdS/BiOBr) is almost 2.8 times and 24.6 times as high as that of pure BiOBr and CdS. The remarkably enhanced photoreactivity should be attributed to the match in the energy levels and close core-satellite structural coupling between the CdS and BiOBr, which greatly facilitates the separation and transfer of photoinduced electron-hole pairs, as confirmed by photoluminescence (PL) and electrochemical impedance spectra (EIS). The present work sheds new light on the construction of highly efficient core-satellite heterojunctional photocatalysts for practical applications.We demonstrate the fabrication of a core-satellite structured BiOBr-CdS photocatalyst with highly efficient photocatalytic reactivity via a facile in situ crystallization approach at room temperature. The transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HR-TEM) results reveal that the BiOBr flakes are surrounded by CdS particles. The coverage of

  6. Paper-Based Analytical Devices Relying on Visible-Light-Enhanced Glucose/Air Biofuel Cells.

    PubMed

    Wu, Kaiqing; Zhang, Yan; Wang, Yanhu; Ge, Shenguang; Yan, Mei; Yu, Jinghua; Song, Xianrang

    2015-11-01

    A strategy that combines visible-light-enhanced biofuel cells (BFCs) and electrochemical immunosensor into paper-based analytical devices was proposed for sensitive detection of the carbohydrate antigen 15-3 (CA15-3). The gold nanoparticle modified paper electrode with large surface area and good conductibility was applied as an effective matrix for primary antibodies. The glucose dehydrogenase (GDH) modified gold-silver bimetallic nanoparticles were used as bioanodic biocatalyst and signal magnification label. Poly(terthiophene) (pTTh), a photoresponsive conducting polymer, served as catalyst in cathode for the reduction of oxygen upon illumination by visible light. In the bioanode, electrons were generated through the oxidation of glucose catalyzed by GDH. The amount of electrons is determined by the amount of GDH, which finally depended on the amount of CA15-3. In the cathode, electrons from the bioanode could combine with the generated holes in the HOMO energy level of cathode catalysts pTTh. Meanwhile, the high energy level photoexcited electrons were generated in the LUMO energy level and involved in the oxygen reduction reaction, finally resulting in an increasing current and a decreasing overpotential. According to the current signal, simple and efficient detection of CA15-3 was achieved.

  7. Unprecedented photocatalytic activity of carbon coated/MoO3 core-shell nanoheterostructurs under visible light irradiation

    NASA Astrophysics Data System (ADS)

    Ghaffar, Iqra; Warsi, Muhammad Farooq; Shahid, Muhammad; Shakir, Imran

    2016-05-01

    We reveal that nano-scale carbon layer deposited by hydrothermal process on molybdenum oxide (MoO3) nanowires surface significantly improve the light absorption range. Furthermore, the graphene-carbon coated MoO3 nanocopmosite (rGO/C-MoO3 nanocomposite) exhibits excellent chemical stability and enhanced photocatalytic activity for methylene blue in aqueous solution under visible light irradiation compared to the bare MoO3 nanowires and carbon coated MoO3 nanowires (C-MoO3 nanowires). The enhanced photocatalytic activity of rGO/C-MoO3 nanocomposite could be attributed to the extended light absorption range, better adsorptivity of dye molecules and efficient separation of photogenerated electrons and holes. Overall, this work provides new insights that the as synthesized rGO/C-MoO3 nanocomposite can be efficiently used as high performance photocatalysts to improve the environmental protection issues under visible light irradiation.

  8. High intensive light channel formation in the post-filamentation region of ultrashort laser pulses in air

    NASA Astrophysics Data System (ADS)

    Geints, Yu E.; Ionin, A. A.; Mokrousova, D. V.; Seleznev, L. V.; Sinitsyn, D. V.; Sunchugasheva, E. S.; Zemlyanov, A. A.

    2016-09-01

    An experimental and theoretical study of the post-filamentation stage of focused high-power Ti:Sa-laser pulses in air is presented. For the first time to our knowledge, the angular and spatial characteristics of specific spatially localized light structures, the ionization-free post-filament channels (PFCs), formed inside the laser beam in the post-filamentation region are systematically quantified under different external focusing and energy of initial pulse. We show that PFC angular divergence tends to decrease with the increase of the laser pulse energy and beam focal distance. These findings are discussed in the framework of the Bessel–Gauss-like beam formation in a course of pulse filamentation stage.

  9. High intensive light channel formation in the post-filamentation region of ultrashort laser pulses in air

    NASA Astrophysics Data System (ADS)

    Geints, Yu E.; Ionin, A. A.; Mokrousova, D. V.; Seleznev, L. V.; Sinitsyn, D. V.; Sunchugasheva, E. S.; Zemlyanov, A. A.

    2016-09-01

    An experimental and theoretical study of the post-filamentation stage of focused high-power Ti:Sa-laser pulses in air is presented. For the first time to our knowledge, the angular and spatial characteristics of specific spatially localized light structures, the ionization-free post-filament channels (PFCs), formed inside the laser beam in the post-filamentation region are systematically quantified under different external focusing and energy of initial pulse. We show that PFC angular divergence tends to decrease with the increase of the laser pulse energy and beam focal distance. These findings are discussed in the framework of the Bessel-Gauss-like beam formation in a course of pulse filamentation stage.

  10. Light scattering investigation above the nematic-smectic-A phase transition in binary mixtures of calamitic and bent-core mesogens.

    PubMed

    Dodge, Mohammad Reza; Petschek, Rolfe G; Rosenblatt, Charles; Neubert, Mary E; Walsh, Margaret E

    2003-09-01

    Quasielastic light scattering measurements were performed in the nematic phase of mixtures consisting of the calamitic mesogen 8OCB doped with small concentrations of the bent-core molecule P-7PIMB. It was found that the regular part of the bend elastic constant decreases strongly with dopant concentration X. Close to the nematic-smectic-A phase transition temperature, the divergent part of the bend elastic constant, which is proportional to the bare correlation length xi(0)(||) parallel to the layer normal, also decreases rapidly with X. The effect of the dopant on xi(0)(||) is examined in brief theoretically.

  11. Laser response of a quartz crystal microbalance: frequency changes induced by light irradiation in the air phase.

    PubMed

    Kawasaki, Takayoshi; Mochida, Tetsuhiro; Katada, Jun-ichi; Okahata, Yoshio

    2009-09-01

    A weak laser irradiation (523-785 nm, 5-60 mW) onto an Au electrode surface of a 27-MHz quartz crystal microbalance (QCM) caused a frequency increase (a mass decrease) in the air phase. These frequency changes depended on the wavelength of the irradiated laser in the order of 523 nm > 636 nm > 785 nm, which corresponds to the light absorbance of the Au electrode of the QCM. The laser response increased linearly with increasing laser power (5-60 mW). In addition, the laser response showed a maximum at the incidence angle of 72 degrees when the P-polarized 636 nm laser was irradiated on the Au surface, due to the evanescent effect. These laser responses were also observed in the humid air of H2O, D2O, and in the vapors of various alcohols. Based on these findings, the observed frequency increase (mass decrease) can be explained by the photo-induced reversible desorption of water molecules from the Au electrode surface of the QCM due to the interfacial property changes.

  12. The osmium tetroxide-p-phenylenediamine procedure reveals the chromatid cores and kinetochores of meiotic chromosomes by light and electron microscopy.

    PubMed

    Antonio, C; González-García, J M; Page, J; Suja, J A; Stockert, J C; Rufas, J S

    1996-11-01

    We analyzed first-metaphase meiotic chromosomes of the grasshopper Chorthippus jucundus by two different methods, i.e., a silver impregnation technique and the osmium tetroxide-p-phenylenediamine (Os-PPD) procedure. The former was applied on squashed testes previously fixed in ethanol-acetic acid, whereas for Os-PPD the material was not subjected to any previous extraction treatment but was fixed in OsO4, treated with PPD, and embedded in Epon 812. Both techniques revealed chromatid cores and kinetochores regardless of the processing of the material (squashed or sectioned). Unstained Os-PPD sections were analyzed by light microscopy and transmission electron microscopy (TEM). The Os-PPD technique provided a high contrast of chromatid cores and kinetochores in relation to the chromatin, which revealed a low electron density. To determine the Os-PPD reaction mechanism, the PAS procedure, as well as scanning electron microscopy (SEM) backscattering and SEM X-ray microanalysis, was performed on sections. By use of the Os-PPD-PAS procedure, glycol groups formed by oxidation of osmium bound to aromatic substrates were detected in chromatid cores and kinetochores by brightfield and fluorescence microscopy. A high Z contrast was detected in these structures by backscattered electron imaging. SEM X-ray microanalysis showed osmium and phosphorus to be the main elements present on the chromatid cores. Taking into account the known reactivity of OsO4 and the present results, the possible participation of nucleic acids as well as proteins in the Os-PPD reaction mechanism and in the composition of chromatid cores and kinetochores is discussed.

  13. Acute dim light at night increases body mass, alters metabolism, and shifts core body temperature circadian rhythms.

    PubMed

    Borniger, Jeremy C; Maurya, Santosh K; Periasamy, Muthu; Nelson, Randy J

    2014-10-01

    The circadian system is primarily entrained by the ambient light environment and is fundamentally linked to metabolism. Mounting evidence suggests a causal relationship among aberrant light exposure, shift work, and metabolic disease. Previous research has demonstrated deleterious metabolic phenotypes elicited by chronic (>4 weeks) exposure to dim light at night (DLAN) (∼ 5 lux). However, the metabolic effects of short-term (<2 weeks) exposure to DLAN are unspecified. We hypothesized that metabolic alterations would arise in response to just 2 weeks of DLAN. Specifically, we predicted that mice exposed to dim light would gain more body mass, alter whole body metabolism, and display altered body temperature (Tb) and activity rhythms compared to mice maintained in dark nights. Our data largely support these predictions; DLAN mice gained significantly more mass, reduced whole body energy expenditure, increased carbohydrate over fat oxidation, and altered temperature circadian rhythms. Importantly, these alterations occurred despite similar activity locomotor levels (and rhythms) and total food intake between groups. Peripheral clocks are potently entrained by body temperature rhythms, and the deregulation of body temperature we observed may contribute to metabolic problems due to "internal desynchrony" between the central circadian oscillator and temperature sensitive peripheral clocks. We conclude that even relatively short-term exposure to low levels of nighttime light can influence metabolism to increase mass gain.

  14. THE INFLUENCE OF INELASTIC NEUTRINO REACTIONS WITH LIGHT NUCLEI ON THE STANDING ACCRETION SHOCK INSTABILITY IN CORE-COLLAPSE SUPERNOVAE

    SciTech Connect

    Furusawa, Shun; Nagakura, Hiroki; Yamada, Shoichi; Sumiyoshi, Kohsuke

    2013-09-01

    We perform numerical experiments to investigate the influence of inelastic neutrino reactions with light nuclei on the standing accretion shock instability (SASI). The time evolution of shock waves is calculated with a simple light-bulb approximation for the neutrino transport and a multi-nuclei equation of state. The neutrino absorptions and inelastic interactions with deuterons, tritons, helions, and alpha particles are taken into account in the hydrodynamical simulations. In addition, the effects of ordinary charged-current interactions with nucleons is addressed in the simulations. Axial symmetry is assumed but no equatorial symmetry is imposed. We show that the heating rates of deuterons reach as high as {approx}10% of those of nucleons around the bottom of the gain region. On the other hand, alpha particles are heated near the shock wave, which is important when the shock wave expands and the density and temperature of matter become low. It is also found that the models with heating by light nuclei evolve differently in the non-linear phase of SASI than do models that lack heating by light nuclei. This result is because matter in the gain region has a varying density and temperature and therefore sub-regions appear that are locally rich in deuterons and alpha particles. Although the light nuclei are never dominant heating sources and they work favorably for shock revival in some cases and unfavorably in other cases, they are non-negligible and warrant further investigation.

  15. White Light Demonstration of One Hundred Parts per Billion Irradiance Suppression in Air by New Starshade Occulters

    NASA Technical Reports Server (NTRS)

    Levinton, Douglas B.; Cash, Webster C.; Gleason, Brian; Kaiser, Michael J.; Levine, Sara A.; Lo, Amy S.; Schindhelm, Eric; Shipley, Ann F.

    2007-01-01

    A new mission concept for the direct imaging of exo-solar planets called the New Worlds Observer (NWO) has been proposed. The concept involves flying a meter-class space telescope in formation with a newly-conceived, specially-shaped, deployable star-occulting shade several meters across at a separation of some tens of thousands of kilometers. The telescope would make its observations from behind the starshade in a volume of high suppression of incident irradiance from the star around which planets orbit. The required level of irradiance suppression created by the starshade for an efficacious mission is of order 0.1 to 10 parts per billion in broadband light. This paper discusses the experimental setup developed to accurately measure the suppression ratio of irradiance produced at the null position behind candidate starshade forms to these levels. It also presents results of broadband measurements which demonstrated suppression levels of just under 100 parts per billion in air using the Sun as a light source. Analytical modeling of spatial irradiance distributions surrounding the null are presented and compared with photographs of irradiance captured in situ behind candidate starshades.

  16. The Mid-infrared Light Curve of Nearby Core-collapse Supernova SN 2011dh (PTF 11eon)

    NASA Astrophysics Data System (ADS)

    Helou, George; Kasliwal, Mansi M.; Ofek, Eran O.; Arcavi, Iair; Surace, Jason; Gal-Yam, Avishay

    2013-11-01

    We present Spitzer observations at 3.6 and 4.5 μm of the supernova SN 2011dh (PTF 11eon) in M51 from 18 days to 625 days after explosion. The mid-infrared emission peaks at 24 days after explosion at a few ×107 L ⊙, and decays more slowly than the visible-light bolometric luminosity. The infrared color temperature cools for the first 90 days and then is constant. Simple numerical models of a thermal echo can qualitatively reproduce the early behavior. At late times, the mid-IR light curve cannot be explained by a simple thermal echo model, suggesting additional dust heating or line emission mechanisms. We also propose that thermal echoes can serve as effective probes to uncover supernovae in heavily obscured environments, and speculate that under the right conditions, integrating the early epoch of the mid-infrared light curve may constrain the total energy in the shock breakout flash.

  17. Experimental observation of surface acoustic wave Brillouin scattering in a small-core photonic crystal fiber

    NASA Astrophysics Data System (ADS)

    Tchahame, Joël. Cabrel; Sylvestre, Thibaut; Phan Huy, Kien; Kudlinski, Alexandre; Laude, Vincent; Beugnot, Jean-Charles

    2016-04-01

    Light propagation in small-core photonic crystal fibers enables tight optical confinement over long propagation lengths to enhance light-matter interactions. Not only can photonic crystal fibers compress light spatially, they also provide a tunable means to control light-hypersound interactions. By exploring Brillouin light scattering in a small-core and high air-filling fraction microstructured fiber, we report the observation of Brillouin scattering from surface acoustic waves at lower frequencies than standard Brillouin scattering from bulk acoustic waves. This effect could find potential applications for optical sensing technologies that exploit surface acoustic waves.

  18. Core/Shell Structured TiO2/CdS Electrode to Enhance the Light Stability of Perovskite Solar Cells.

    PubMed

    Hwang, Insung; Baek, Minki; Yong, Kijung

    2015-12-23

    In this work, enhanced light stability of perovskite solar cell (PSC) achieved by the introduction of a core/shell-structured CdS/TiO2 electrode and the related mechanism are reported. By a simple solution-based process (SILAR), a uniform CdS shell was coated onto the surface of a TiO2 layer, suppressing the activation of intrinsic trap sites originating from the oxygen vacancies of the TiO2 layer. As a result, the proposed CdS-PSC exhibited highly improved light stability, maintaining nearly 80% of the initial efficiency after 12 h of full sunlight illumination. From the X-ray diffraction analyses, it is suggested that the degradation of the efficiency of PSC during illumination occurs regardless of the decomposition of the perovskite absorber. Considering the light-soaking profiles of the encapsulated cells and the OCVD characteristics, it is likely that the CdS shell had efficiently suppressed the undesirable electron kinetics, such as trapping at the surface defects of the TiO2 and preventing the resultant charge losses by recombination. This study suggests that further complementary research on various effective methods for passivation of the TiO2 layer would be highly meaningful, leading to insight into the fabrication of PSCs stable to UV-light for a long time.

  19. Two lighter than air systems in opposing flight regimes: An unmanned short haul, heavy load transport balloon and a manned, light payload airship

    NASA Technical Reports Server (NTRS)

    Pohl, R. A.

    1975-01-01

    Lighter Than Air vehicles are generally defined or categorized by the shape of the balloon, payload capacity and operational flight regime. Two balloon systems that are classed as being in opposite categories are described. One is a cable guided, helium filled, short haul, heavy load transport Lighter Than Air system with a natural shaped envelope. The other is a manned, aerodynamic shaped airship which utilizes hot air as the buoyancy medium and is in the light payload class. While the airship is in the design/fabrication phase with flight tests scheduled for the latter part of 1974, the transport balloon system has been operational for some eight years.

  20. Banded transformer cores

    NASA Technical Reports Server (NTRS)

    Mclyman, C. W. T. (Inventor)

    1974-01-01

    A banded transformer core formed by positioning a pair of mated, similar core halves on a supporting pedestal. The core halves are encircled with a strap, selectively applying tension whereby a compressive force is applied to the core edge for reducing the innate air gap. A dc magnetic field is employed in supporting the core halves during initial phases of the banding operation, while an ac magnetic field subsequently is employed for detecting dimension changes occurring in the air gaps as tension is applied to the strap.

  1. Differential Synthesis of Photosystem Cores and Light-Harvesting Antenna during Proplastid to Chloroplast Development in Spirodela oligorrhiza.

    PubMed

    McCormac, D J; Greenberg, B M

    1992-03-01

    Proplastids and etioplasts are common starting points for monitoring chloroplast development in higher plants. Although proplastids are the primary precursor of chloroplasts, most proplastid to chloroplast systems are cumbersome to study temporally. Conversely, the etioplast to chloroplast transition is initiated by light and is readily examined as a function of time. Etioplasts, however, are found mostly in plants germinated in the dark and are not an obligatory step in chloroplast development. We have chosen to study chloroplast ontogeny in Spirodela oligorrhiza (Kurtz) Hegelm (a C(3)-monocot) because of its unique ability to grow indefinitely in the dark. Ultrastructural, physiological, and molecular evidence is presented in support of a temporal, light-triggered proplastid to chloroplast transition in Spirodela. The dark-grown plants are devoid of chlorophyll, and upon illumination synchronously green over a 3- to 5-day period. Synthesis of chloroplast proteins involved in photosynthesis is coincident with thylakoid assembly, chlorophyll accumulation, and appearance of CO(2) fixation activity. Interestingly, the developmental sequence in Spirodela was slow enough to reveal that biosynthesis of the D1 photosystem II reaction center protein precedes biosynthesis of the major light-harvesting antenna proteins. This, coupled with the high chlorophyll a/b ratio observed early in development, indicated that reaction center assembly occurred prior to accumulation of the light-harvesting complexes. Thus, with Spirodela one can study proplastid to chloroplast conversions temporally in higher plants and follow the process on a time scale that enables a detailed dissection of plastid maturation processes.

  2. Light Water Breeder end-of-life component examinations at Shippingport Atomic Power Station and module visual and dimensional examinations at Expended Core Facility (LWBR Development Program)

    SciTech Connect

    Wargo, J.E.

    1987-10-01

    This report presents highlights of visual and dimensional examinations of the Light Water Breeder Reactor fuel assemblies and selected core components following five years of power operation in which the core achieved 29,047 effective full power hours. Each type of fuel assembly (seed, blanket, and reflector) is described, and the end-of-life conditions are documented in photographs and data plots. Fuel modules were examined immediately after removal from the reactor vessel at the Shippingport Atomic Power Station and after shipment to the Expended Core Facility at the Naval Reactors Facility in Idaho. Further inspection was performed on one seed and one reflector assembly after their external support shells were removed. Module length changes and bow data are presented for selected assemblies. Structural component examinations include magnetic particle testing and ultrasonic test inspection of the LWBR reactor vessel closure head. Visual inspections were also performed on compression sleeves and guide tube extensions which formed part of the guide path for the movable fuel assemblies. 4 refs., 103 figs., 5 tabs.

  3. Bright white-light emission from Ag/SiO2/CdS-ZnS core/shell/shell plasmon couplers

    NASA Astrophysics Data System (ADS)

    Liao, Chen; Tang, Luping; Gao, Xiaoqin; Xu, Ruilin; Zhang, Huichao; Yu, Yongya; Lu, Changgui; Cui, Yiping; Zhang, Jiayu

    2015-12-01

    Well-defined plasmon couplers (PCs) that comprise a Ag core overcoated with a SiO2 shell with controlled thickness, followed by a monolayer of CdS-ZnS core-shell quantum dots (QDs) were synthesized to modify the emission from trap-rich CdS-ZnS QDs by adjusting the distance between the QDs and Ag nanoparticles (NPs). When the thickness of the SiO2 shell was 10 nm, because the shell could effectively suppress the non-radiative energy transfer from the semiconductor QDs to the metal NPs and the localized surface plasmon resonance (LSPR) of the Ag NPs spectrally matched the emission peak of the CdS-ZnS QDs to bring about strong plasmon coupling, optimum enhancements of the surface state emission (SSE) (17 times) and band-edge emission (BEE) (4 times) were simultaneously realized and the SSE to BEE intensity ratio was increased to 55%. As a result, a bright white-light source with 1931 Commission Internationale d'Eclairage (CIE) chromaticity coordinates of (0.32, 0.34) was realized by the superposition of the two emissions. The experimental results from Ag/SiO2/CdSe-ZnS and the Ag/SiO2/CdS:Mn-ZnS core/shell/shell PCs indicated that suppressing the non-radiative decay rate (knr) was the underlying mechanism for plasmon coupling fluorescence enhancement.

  4. Electrical current leakage and open-core threading dislocations in AlGaN-based deep ultraviolet light-emitting diodes

    SciTech Connect

    Moseley, Michael Allerman, Andrew; Crawford, Mary; Wierer, Jonathan J.; Smith, Michael; Biedermann, Laura

    2014-08-07

    Electrical current transport through leakage paths in AlGaN-based deep ultraviolet (DUV) light-emitting diodes (LEDs) and their effect on LED performance are investigated. Open-core threading dislocations, or nanopipes, are found to conduct current through nominally insulating Al{sub 0.7}Ga{sub 0.3}N layers and limit the performance of DUV-LEDs. A defect-sensitive phosphoric acid etch reveals these open-core threading dislocations in the form of large, micron-scale hexagonal etch pits visible with optical microscopy, while closed-core screw-, edge-, and mixed-type threading dislocations are represented by smaller and more numerous nanometer-scale pits visible by atomic-force microscopy. The electrical and optical performances of DUV-LEDs fabricated on similar Si-doped Al{sub 0.7}Ga{sub 0.3}N templates are found to have a strong correlation to the density of these nanopipes, despite their small fraction (<0.1% in this study) of the total density of threading dislocations.

  5. Delivery of high energy Er:YAG pulsed laser light at 2.94 µm through a silica hollow core photonic crystal fibre.

    PubMed

    Urich, A; Maier, R R J; Mangan, B J; Renshaw, S; Knight, J C; Hand, D P; Shephard, J D

    2012-03-12

    In this paper the delivery of high power Er:YAG laser pulses through a silica hollow core photonic crystal fibre is demonstrated. The Er:YAG wavelength of 2.94 µm is well beyond the normal transmittance of bulk silica but the unique hollow core guidance allows silica to guide in this regime. We have demonstrated for the first time the ability to deliver high energy pulses through an all-silica fibre at 2.94 µm. These silica fibres are mechanically and chemically robust, biocompatible and have low sensitivity to bending. A maximum pulse energy of 14 mJ at 2.94 µm was delivered through the fibre. This, to our knowledge, is the first time a silica hollow core photonic crystal fibre has been shown to transmit 2.94 μm laser light at a fluence exceeding the thresholds required for modification (e.g. cutting and drilling) of hard biological tissue. Consequently, laser delivery systems based on these fibres have the potential for the realization of novel, minimally-invasive surgical procedures.

  6. Horizontal coring using air as the circulating fluid: Some prototype studies conducted in G Tunnel at the Nevada Test Site for the Yucca Mountain Project

    SciTech Connect

    Chornack, M.P.; French, C.A.

    1989-12-31

    Horizontal coring using air as the circulating fluid has been conducted in the G Tunnel Underground Facility (GTUF) at the Nevada Test Site. This work is part of the prototype investigations of hydrogeology for the Yucca Mountain Project. The work is being conducted to develop methods and procedures that will be used at the Department of Energy`s Yucca Mountain Site, a candidate site for the nation`s first high-level nuclear waste repository, during the site characterization phase of the investigations. The United States Geological Survey (USGS) is conducting this prototype testing under the guidance of the Los Alamos National Laboratory (LANL) and in conjunction with Reynolds Electrical & Engineering Company (REECo), the drilling contractor. 7 refs., 8 figs., 5 tabs.

  7. Hollow-Core Fiber Lamp

    NASA Technical Reports Server (NTRS)

    Yi, Lin (Inventor); Tjoelker, Robert L. (Inventor); Burt, Eric A. (Inventor); Huang, Shouhua (Inventor)

    2016-01-01

    Hollow-core capillary discharge lamps on the millimeter or sub-millimeter scale are provided. The hollow-core capillary discharge lamps achieve an increased light intensity ratio between 194 millimeters (useful) and 254 millimeters (useless) light than conventional lamps. The capillary discharge lamps may include a cone to increase light output. Hollow-core photonic crystal fiber (HCPCF) may also be used.

  8. Quantification of surface temperature changes during rapid climatic events 18-20 from air isotopic measurements in NorthGRIP ice cores

    NASA Astrophysics Data System (ADS)

    Landais, A.; Barnola, J. M.; Goujon, C.; Jouzel, J.; Caillon, N.; Chappellaz, J.; Johnsen, S.

    2003-04-01

    Although water stable isotope profiles from Greenland ice cores have evidenced the succession of glacial climate variability, their quantitative interpretation in terms of temperature changes remains uncertain due to possible changes in the seasonality of the precipitation. Here we use an alternative paleothermometry method based on the gravitational and thermal diffusion of permanent gasesin the firn (porous upper part of the ice sheets) in response to abrupt temperature changes. The variety of measurements conducted on the air trapped in the ice enables to study the relative timing of fluctuations in local temperature (isotopic measurements of 15N/14N, d15N, and 40Ar/36Ar, d40Ar), ice volume and Dole effect (18O/16O of atmospheric oxygene, d18Oatm) and temperate and tropical wetland CH4 production. We have obtained high resolution profiles of these tracers measured along the Dansgaard-Oeschger events 18, 19 and 20 from the recently drilled NorthGRIP ice core (300 km to the north of GRIP and GISP2). Isotopic nitrogen data combined to CH4 on the whole profile firmly confirm the in phase increase of both temperature and CH4 during Dansgard-Oeschger events. d15N, d40Ar and firn densification modeling enable us to estimate the associated temperature changes which can be compared to the estimate by Lang et al (GRIP event 19). Indeed, nitrogen combined to argon isotopic anomalies enable to extract the sole thermal effect from the total signal (gravitational and thermal). Finally, the air d18Oatm shows a slow increasing trend due to the ice sheet growth but also small fluctuations maybe related to the DO events (either due to effusion in the ice or to biosphere modification).

  9. Lighting

    SciTech Connect

    Audin, L.

    1994-12-31

    EPAct covers a vast territory beyond lighting and, like all legislation, also contains numerous {open_quotes}favors,{close_quotes} compromises, and even some sleight-of-hand. Tucked away under Title XIX, for example, is an increase from 20% to 28% tax on gambling winnings, effective January 1, 1993 - apparently as a way to help pay for new spending listed elsewhere in the bill. Overall, it is a landmark piece of legislation, about a decade overdue. It remains to be seen how the Federal Government will enforce upgrading of state (or even their own) energy codes. There is no mention of funding for {open_quotes}energy police{close_quotes} in EPAct. Merely creating such a national standard, however, provides a target for those who sincerely wish to create an energy-efficient future.

  10. Hot prominence detected in the core of a coronal mass ejection: Analysis of SOHO/UVCS Lα and SOHO/LASCO visible-light observations

    NASA Astrophysics Data System (ADS)

    Heinzel, P.; Susino, R.; Jejčič, S.; Bemporad, A.; Anzer, U.

    2016-05-01

    Context. The paper deals with the physics of erupting prominences in the core of coronal mass ejections (CME). Aims: We determine the physical parameters of an erupting prominence embedded in the core of a CME using SOHO/UVCS hydrogen Lα and Lβ lines and SOHO/LASCO visible light observations. In particular we analyze the CME event observed on August 2, 2000. We develop the non-LTE (NLTE; i.e. considering departures from the local thermodynamic equilibrium - LTE) spectral diagnostics based on Lα and visible light observations. Methods: Our method is based on 1D NLTE modeling of eruptive prominences and takes into account the effect of large flow velocities, which reach up to 300 km s-1 for the studied event (the so-called Doppler dimming). The NLTE radiative-transfer method can be used for both optically thin and thick prominence structures. We combine spectroscopic UVCS observations of an erupting prominence in the core of a CME with visible light images from LASCO-C2 in order to derive the geometrical parameters like projected thickness and velocity, together with the effective temperature and column density of electrons. These are then used to constrain our NLTE radiative transfer modeling which provides the kinetic temperature, microturbulent velocity, gas pressure, ionization degree, the line opacities, and the prominence effective thickness (geometrical filling factor). Results: Analysis was made for 69 observational points (spatial pixels) inside the whole erupting prominence. Roughly one-half of them show a non-negligible Lα optical thickness for flow velocity 300 km s-1 and about one-third for flow velocity 150 km s-1. All pixels with Lατ0 ≤ 0.3 have been considered for further analysis, which is presented in the form of statistical distributions (histograms) of various physical quantities such as the kinetic temperature, gas pressure, and electron density for two representative flow velocities (150 and 300 km s-1) and non-zero microturbulence. For

  11. Visible-Light-Responsive Catalysts Using Quantum Dot-Modified TiO2 for Air and Water Purification

    NASA Technical Reports Server (NTRS)

    Coutts, Janelle L.; Hintze, Paul E.; Clausen, Christian; Richards, Jeffrey Todd

    2014-01-01

    Photocatalysis, the oxidation or reduction of contaminants by light-activated catalysts, utilizing titanium dioxide (TiO2) as the catalytic substrate has been widely studied for trace contaminant control in both air and water applications. The interest in this process is due primarily to its low energy consumption and capacity for catalyst regeneration. Titanium dioxide requires ultraviolet light for activation due to its relatively large band gap energy of 3.2 eV. Traditionally, Hg-vapor fluorescent light sources are used in PCO reactors; however, the use of mercury precludes the use of this PCO technology in a spaceflight environment due to concerns over crew Hg exposure. The development of a visible-light responsive (VLR) TiO2-based catalyst would eliminate the concerns over mercury contamination. Further, VLR development would allow for the use of ambient visible solar radiation or highly efficient LEDs, both of which would make PCO approaches more efficient, flexible, economical, and safe. Though VLR catalyst development has been an active area of research for the past two decades, there are few commercially available VLR catalysts. Those VLR catalysts that are commercially available do not have adequate catalytic activity, in the visible region, to make them competitive with those operating under UV irradiation. This study was initiated to develop more effective VLR catalysts through a novel method in which quantum dots (QD) consisting of narrow band gap semiconductors (e.g., CdS, CdSe, PbS, ZnSe, etc.) are coupled to TiO2 via two preparation methods: 1) photodeposition and 2) mechanical alloying using a high-speed ball mill. A library of catalysts was developed and screened for gas and aqueous phase applications using ethanol and 4-chlorophenol as the target contaminants, respectively. Both target compounds are well studied in photocatalytic systems and served as model contaminants for this research. Synthesized catalysts were compared in terms of

  12. Glycol methacrylate (GMA) embedding for light microscopy. II. Immunohistochemical analysis of semithin sections of undecalcified marrow cores.

    PubMed

    Islam, A; Archimbaud, E; Henderson, E S; Han, T

    1988-08-01

    A routine method allows bone marrow biopsy specimens to be embedded in glycol methacrylate (GMA), a water miscible plastic, and to benefit from the advantages of good morphology with immunoperoxidase detection of a wide range of cellular antigens useful in diagnosing and classifying various haematopoietic disorders. Marrow cores were fixed in cold Bouin's solution, rinsed in cold phosphate buffer, dehydrated in cold methanol, infiltrated and embedded in cold GMA, then polymerised at 4 degrees C. Sections were cut at 2 micron thickness with a Tungsten carbide knife in a Jung's high performance microtome (Autocut). Antigenecity was preserved when drying slides at room temperature but pronase digestion was necessary to re-expose the antigens in bone marrow biopsy sections embedded in GMA. Histostik, a new adhesive, was used to coat the glass slides to prevent section loss during enzyme digestion and immunostaining procedures. This method of adapting plastic embedding to undecalcified marrow cores preserves marrow architecture and cellular details and it can serve as a useful adjunct to analyse the bone marrow from patients with myeloproliferative and lymphoproliferative disorders. This technique may also be applicable in non-haematological malignant conditions which affect the marrow.

  13. Muscle, Skin and Core Temperature after −110°C Cold Air and 8°C Water Treatment

    PubMed Central

    Costello, Joseph Thomas; Culligan, Kevin; Selfe, James; Donnelly, Alan Edward

    2012-01-01

    The aim of this investigation was to elucidate the reductions in muscle, skin and core temperature following exposure to −110°C whole body cryotherapy (WBC), and compare these to 8°C cold water immersion (CWI). Twenty active male subjects were randomly assigned to a 4-min exposure of WBC or CWI. A minimum of 7 days later subjects were exposed to the other treatment. Muscle temperature in the right vastus lateralis (n = 10); thigh skin (average, maximum and minimum) and rectal temperature (n = 10) were recorded before and 60 min after treatment. The greatest reduction (P<0.05) in muscle (mean ± SD; 1 cm: WBC, 1.6±1.2°C; CWI, 2.0±1.0°C; 2 cm: WBC, 1.2±0.7°C; CWI, 1.7±0.9°C; 3 cm: WBC, 1.6±0.6°C; CWI, 1.7±0.5°C) and rectal temperature (WBC, 0.3±0.2°C; CWI, 0.4±0.2°C) were observed 60 min after treatment. The largest reductions in average (WBC, 12.1±1.0°C; CWI, 8.4±0.7°C), minimum (WBC, 13.2±1.4°C; CWI, 8.7±0.7°C) and maximum (WBC, 8.8±2.0°C; CWI, 7.2±1.9°C) skin temperature occurred immediately after both CWI and WBC (P<0.05). Skin temperature was significantly lower (P<0.05) immediately after WBC compared to CWI. The present study demonstrates that a single WBC exposure decreases muscle and core temperature to a similar level of those experienced after CWI. Although both treatments significantly reduced skin temperature, WBC elicited a greater decrease compared to CWI. These data may provide information to clinicians and researchers attempting to optimise WBC and CWI protocols in a clinical or sporting setting. PMID:23139763

  14. THE MID-INFRARED LIGHT CURVE OF NEARBY CORE-COLLAPSE SUPERNOVA SN 2011dh (PTF 11eon)

    SciTech Connect

    Helou, George; Surace, Jason; Kasliwal, Mansi M.; Ofek, Eran O.; Arcavi, Iair; Gal-Yam, Avishay

    2013-11-20

    We present Spitzer observations at 3.6 and 4.5 μm of the supernova SN 2011dh (PTF 11eon) in M51 from 18 days to 625 days after explosion. The mid-infrared emission peaks at 24 days after explosion at a few ×10{sup 7} L {sub ☉}, and decays more slowly than the visible-light bolometric luminosity. The infrared color temperature cools for the first 90 days and then is constant. Simple numerical models of a thermal echo can qualitatively reproduce the early behavior. At late times, the mid-IR light curve cannot be explained by a simple thermal echo model, suggesting additional dust heating or line emission mechanisms. We also propose that thermal echoes can serve as effective probes to uncover supernovae in heavily obscured environments, and speculate that under the right conditions, integrating the early epoch of the mid-infrared light curve may constrain the total energy in the shock breakout flash.

  15. Dual-core antiresonant hollow core fibers.

    PubMed

    Liu, Xuesong; Fan, Zhongwei; Shi, Zhaohui; Ma, Yunfeng; Yu, Jin; Zhang, Jing

    2016-07-25

    In this work, dual-core antiresonant hollow core fibers (AR-HCFs) are numerically demonstrated, based on our knowledge, for the first time. Two fiber structures are proposed. One is a composite of two single-core nested nodeless AR-HCFs, exhibiting low confinement loss and a circular mode profile in each core. The other has a relatively simple structure, with a whole elliptical outer jacket, presenting a uniform and wide transmission band. The modal couplings of the dual-core AR-HCFs rely on a unique mechanism that transfers power through the air. The core separation and the gap between the two cores influence the modal coupling strength. With proper designs, both of the dual-core fibers can have low phase birefringence and short modal coupling lengths of several centimeters.

  16. Air stable organic salt as an n-type dopant for efficient and stable organic light-emitting diodes.

    PubMed

    Bin, Zhengyang; Duan, Lian; Qiu, Yong

    2015-04-01

    Air-stable and low-temperature-evaporable n-type dopants are highly desired for efficient and stable organic light-emitting diodes (OLEDs). In this work, 2-(2-Methoxyphenyl)-1,3-dimethyl-1H-benzoimidazol-3-ium iodide (o-MeO-DMBI-I), a thermally decomposable precursor of organic radical o-MeO-DMBI, has been employed as a novel n-type dopant in OLEDs, because of its air stability, low decomposition temperature, and lack of atom diffusion. The n-type electrical doping is evidenced by the rapid increase in current density of electron-only devices and the large improvement in conductivity, originated from increased electron concentration in electron-transport layer (ETL) and reduced electron injection barrier. A highly efficient and stable OLED is created using o-MeO-DMBI as an n-type dopant in Bphen. Compared with the control device with its high-temperature-evaporable n-type dopant cesium carbonate (Cs2CO3), o-MeO-DMBI-doped device showed an incredible boom in current efficiency from 28.6 to 42.2 cd/A. Moreover, the lifetime (T(70%)) of o-MeO-DMBI-doped device is 45 h, more than 20 times longer than that of the Cs2CO3-doped device (2 h). The enhanced efficiency and stability are attributed to the improved balance of holes and electrons in the emissive layer, and the eliminated atom diffusion of cesium. PMID:25768295

  17. Interfacial redox reaction-directed synthesis of silver@cerium oxide core-shell nanocomposites as catalysts for rechargeable lithium-air batteries

    NASA Astrophysics Data System (ADS)

    Liu, Ying; Wang, Man; Cao, Lu-Jie; Yang, Ming-Yang; Ho-Sum Cheng, Samson; Cao, Chen-Wei; Leung, Kwan-Lan; Chung, Chi-Yuen; Lu, Zhou-Guang

    2015-07-01

    A facile oxidation-reduction reaction method has been implemented to prepare pomegranate-like Ag@CeO2 multicore-shell structured nanocomposites. Under Ar atmosphere, redox reaction automatically occurs between AgNO3 and Ce(NO3)3 in an alkaline solution, where Ag+ is reduced to Ag nanopartilces and Ce3+ is simultaneously oxidized to form CeO2, followed by the self-assembly to form the pomegranate-like multicore-shell structured Ag@CeO2 nanocomposites driven by thermodynamic equilibrium. No other organic amines or surfactants are utilized in the whole reaction system and only NaOH instead of organic reducing agent is used to prevent the introduction of a secondary reducing byproduct. The as-obtained pomegranate-like Ag@CeO2 multicore-shell structured nanocomposites have been characterized as electro-catalysts for the air cathode of lithium-air batteries operated in a simulated air environment. Superior electrochemical performance with high discharge capacity of 3415 mAh g-1 at 100 mA g-1, stable cycling and small charge/discharge polarization voltage is achieved, which is much better than that of the CeO2 or simple mixture of CeO2 and Ag. The enhanced properties can be primarily attributed to the synergy effect between the Ag core and the CeO2 shell resulting from the unique pomegranate-like multicore-shell nanostructures possessing plenty of active sites to promote the facile formation and decomposition of Li2O2.

  18. Core-shell magnetite-silica composite nanoparticles enhancing DNA damage induced by a photoactive platinum-diimine complex in red light.

    PubMed

    Zhang, Zhigang; Chai, Aiyun

    2012-12-01

    Lack of solubility under physiological conditions poses an additional risk for toxicity and side effects for intravenous delivery of the photodynamic therapeutic agent in vivo. Employing magnetite-silica composite nanoparticles as carriers of the photodynamic therapeutic agents may be a promising way to solve the problem. In this study, core-shell magnetite-silica composite nanoparticles were prepared by a sol-gel method, and characterized by X-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy and dynamic light scattering, then they were used as carriers of a photoactive platinum diimine complex. The interactions of the photosensitizer-loaded magnetic composite nanoparticles with DNA in red light were monitored by agarose-gel electrophoresis. The results suggest that high doses of magnetite-silica composite nanoparticles might facilitate the transformation of covalently closed circular (ccc)-DNA band to open circular (oc)-DNA band though they are harmless to DNA at their low concentrations, therefore enhancing the extent of DNA damage caused by the metal complex in red light.

  19. Air-snow transfer of nitrate on the East Antarctic Plateau - Part 2: An isotopic model for the interpretation of deep ice-core records

    NASA Astrophysics Data System (ADS)

    Erbland, J.; Savarino, J.; Morin, S.; France, J. L.; Frey, M. M.; King, M. D.

    2015-10-01

    Unraveling the modern budget of reactive nitrogen on the Antarctic Plateau is critical for the interpretation of ice-core records of nitrate. This requires accounting for nitrate recycling processes occurring in near-surface snow and the overlying atmospheric boundary layer. Not only concentration measurements but also isotopic ratios of nitrogen and oxygen in nitrate provide constraints on the processes at play. However, due to the large number of intertwined chemical and physical phenomena involved, numerical modeling is required to test hypotheses in a quantitative manner. Here we introduce the model TRANSITS (TRansfer of Atmospheric Nitrate Stable Isotopes To the Snow), a novel conceptual, multi-layer and one-dimensional model representing the impact of processes operating on nitrate at the air-snow interface on the East Antarctic Plateau, in terms of concentrations (mass fraction) and nitrogen (δ15N) and oxygen isotopic composition (17O excess, Δ17O) in nitrate. At the air-snow interface at Dome C (DC; 75° 06' S, 123° 19' E), the model reproduces well the values of δ15N in atmospheric and surface snow (skin layer) nitrate as well as in the δ15N profile in DC snow, including the observed extraordinary high positive values (around +300 ‰) below 2 cm. The model also captures the observed variability in nitrate mass fraction in the snow. While oxygen data are qualitatively reproduced at the air-snow interface at DC and in East Antarctica, the simulated Δ17O values underestimate the observed Δ17O values by several per mill. This is explained by the simplifications made in the description of the atmospheric cycling and oxidation of NO2 as well as by our lack of understanding of the NOx chemistry at Dome C. The model reproduces well the sensitivity of δ15N, Δ17O and the apparent fractionation constants (15ϵapp, 17Eapp) to the snow accumulation rate. Building on this development, we propose a framework for the interpretation of nitrate records

  20. Air-snow transfer of nitrate on the East Antarctic plateau - Part 2: An isotopic model for the interpretation of deep ice-core records

    NASA Astrophysics Data System (ADS)

    Erbland, J.; Savarino, J.; Morin, S.; France, J. L.; Frey, M. M.; King, M. D.

    2015-03-01

    Unraveling the modern budget of reactive nitrogen on the Antarctic plateau is critical for the interpretation of ice core records of nitrate. This requires accounting for nitrate recycling processes occurring in near surface snow and the overlying atmospheric boundary layer. Not only concentration measurements, but also isotopic ratios of nitrogen and oxygen in nitrate, provide constraints on the processes at play. However, due to the large number of intertwined chemical and physical phenomena involved, numerical modelling is required to test hypotheses in a quantitative manner. Here we introduce the model "TRansfer of Atmospheric Nitrate Stable Isotopes To the Snow" (TRANSITS), a novel conceptual, multi-layer and one-dimensional model representing the impact of processes operating on nitrate at the air-snow interface on the East Antarctic plateau, in terms of concentrations (mass fraction) and the nitrogen (δ15N) and oxygen isotopic composition (17O}-excess, Δ17O) in nitrate. At the air-snow interface at Dome C (DC, 75°06' S, 123°19' E), the model reproduces well the values of δ15N in atmospheric and surface snow (skin layer) nitrate as well as in the δ15N profile in DC snow including the observed extraordinary high positive values (around +300 ‰) below 20 unit{cm}. The model also captures the observed variability in nitrate mass fraction in the snow. While oxygen data are qualitatively reproduced at the air-snow interface at DC and in East Antarctica, the simulated Δ17O values underestimate the observed Δ17O values by a few ‰. This is explained by the simplifications made in the description of the atmospheric cycling and oxidation of NO2. The model reproduces well the sensitivity of δ15N, Δ17O and the apparent fractionation constants (15ϵapp, 17Eapp) to the snow accumulation rate. Building on this development, we propose a framework for the interpretation of nitrate records measured from ice cores. Measurement of nitrate mass fractions

  1. Core-shell InGaN/GaN nanowire light emitting diodes analyzed by electron beam induced current microscopy and cathodoluminescence mapping

    NASA Astrophysics Data System (ADS)

    Tchernycheva, M.; Neplokh, V.; Zhang, H.; Lavenus, P.; Rigutti, L.; Bayle, F.; Julien, F. H.; Babichev, A.; Jacopin, G.; Largeau, L.; Ciechonski, R.; Vescovi, G.; Kryliouk, O.

    2015-07-01

    We report on the electron beam induced current (EBIC) microscopy and cathodoluminescence (CL) characterization correlated with compositional analysis of light emitting diodes based on core/shell InGaN/GaN nanowire arrays. The EBIC mapping of cleaved fully operational devices allows to probe the electrical properties of the active region with a nanoscale resolution. In particular, the electrical activity of the p-n junction on the m-planes and on the semi-polar planes of individual nanowires is assessed in top view and cross-sectional geometries. The EBIC maps combined with CL characterization demonstrate the impact of the compositional gradients along the wire axis on the electrical and optical signals: the reduction of the EBIC signal toward the nanowire top is accompanied by an increase of the CL intensity. This effect is interpreted as a consequence of the In and Al gradients in the quantum well and in the electron blocking layer, which influence the carrier extraction efficiency. The interface between the nanowire core and the radially grown layer is shown to produce in some cases a transitory EBIC signal. This observation is explained by the presence of charged traps at this interface, which can be saturated by electron irradiation.We report on the electron beam induced current (EBIC) microscopy and cathodoluminescence (CL) characterization correlated with compositional analysis of light emitting diodes based on core/shell InGaN/GaN nanowire arrays. The EBIC mapping of cleaved fully operational devices allows to probe the electrical properties of the active region with a nanoscale resolution. In particular, the electrical activity of the p-n junction on the m-planes and on the semi-polar planes of individual nanowires is assessed in top view and cross-sectional geometries. The EBIC maps combined with CL characterization demonstrate the impact of the compositional gradients along the wire axis on the electrical and optical signals: the reduction of the EBIC

  2. Attribution of aerosol light absorption to black carbon, brown carbon, and dust in China - interpretations of atmospheric measurements during EAST-AIRE

    NASA Astrophysics Data System (ADS)

    Yang, M.; Howell, S. G.; Zhuang, J.; Huebert, B. J.

    2009-03-01

    Black carbon, brown carbon, and mineral dust are three of the most important light absorbing aerosols. Their optical properties differ greatly and are distinctive functions of the wavelength of light. Most optical instruments that quantify light absorption, however, are unable to distinguish one type of absorbing aerosol from another. It is thus instructive to separate total absorption from these different light absorbers to gain a better understanding of the optical characteristics of each aerosol type. During the EAST-AIRE (East Asian Study of Tropospheric Aerosols: an International Regional Experiment) campaign near Beijing, we measured light scattering using a nephelometer, and light absorption using an aethalometer and a particulate soot absorption photometer. We also measured the total mass concentrations of carbonaceous (elemental and organic carbon) and inorganic particulates, as well as aerosol number and mass distributions. We were able to identify periods during the campaign that were dominated by dust, biomass burning, fresh (industrial) chimney plumes, other coal burning pollution, and relatively clean (background) air for Northern China. Each of these air masses possessed distinct intensive optical properties, including the single scatter albedo and Ångstrom exponents. Based on the wavelength-dependence and particle size distribution, we apportioned total light absorption to black carbon, brown carbon, and dust; their mass absorption efficiencies at 550 nm were estimated to be 9.5, 0.5 (a lower limit value), and 0.03 m2/g, respectively. While agreeing with the common consensus that black carbon is the most important light absorber in the mid-visible, we demonstrated that brown carbon and dust could also cause significant absorption, especially at shorter wavelengths.

  3. Attribution of aerosol light absorption to black carbon, brown carbon, and dust in China - interpretations of atmospheric measurements during EAST-AIRE

    NASA Astrophysics Data System (ADS)

    Yang, M.; Howell, S. G.; Zhuang, J.; Huebert, B. J.

    2008-06-01

    Black carbon, brown carbon, and mineral dust are three of the most important light absorbing aerosols. Their optical properties differ greatly and are distinctive functions of the wavelength of light. Most optical instruments that quantify light absorption, however, are unable to distinguish one type of absorbing aerosol from another. It is thus instructive to separate total absorption from these different light absorbers to gain a better understanding of the optical characteristics of each aerosol type. During the EAST-AIRE (East Asian Study of Tropospheric Aerosols: an International Regional Experiment) campaign near Beijing, we measured light scattering using a nephelometer, and light absorption using an aethalometer and a particulate soot absorption photometer. We also measured the total mass concentrations of carbonaceous (elemental and organic carbon) and inorganic particulates, as well as aerosol number and mass distributions. We were able to identify periods during the campaign that were dominated by dust, biomass burning, fresh (industrial) chimney plumes, other coal burning pollution, and relatively clean (background) air for Northern China. Each of these air masses possessed distinct intensive optical properties, including the single scatter albedo and Ångstrom exponents. Based on the wavelength-dependence and particle size distribution, we apportioned total light absorption to black carbon, brown carbon, and dust; their mass absorption efficiencies at 550 nm were estimated to be 9.5, 0.5, and 0.03 m2/g, respectively. While agreeing with the common consensus that BC is the most important light absorber in the mid-visible, we demonstrated that brown carbon and dust could also cause significant absorption, especially at shorter wavelengths.

  4. High variability of Greenland surface temperature over the past 4000 years estimated from trapped air in an ice core

    NASA Astrophysics Data System (ADS)

    Kobashi, Takuro; Kawamura, Kenji; Severinghaus, Jeffrey P.; Barnola, Jean-Marc; Nakaegawa, Toshiyuki; Vinther, Bo M.; Johnsen, Sigfús J.; Box, Jason E.

    2011-11-01

    Greenland recently incurred record high temperatures and ice loss by melting, adding to concerns that anthropogenic warming is impacting the Greenland ice sheet and in turn accelerating global sea-level rise. Yet, it remains imprecisely known for Greenland how much warming is caused by increasing atmospheric greenhouse gases versus natural variability. To address this need, we reconstruct Greenland surface snow temperature variability over the past 4000 years at the GISP2 site (near the Summit of the Greenland ice sheet; hereafter referred to as Greenland temperature) with a new method that utilises argon and nitrogen isotopic ratios from occluded air bubbles. The estimated average Greenland snow temperature over the past 4000 years was -30.7°C with a standard deviation of 1.0°C and exhibited a long-term decrease of roughly 1.5°C, which is consistent with earlier studies. The current decadal average surface temperature (2001-2010) at the GISP2 site is -29.9°C. The record indicates that warmer temperatures were the norm in the earlier part of the past 4000 years, including century-long intervals nearly 1°C warmer than the present decade (2001-2010). Therefore, we conclude that the current decadal mean temperature in Greenland has not exceeded the envelope of natural variability over the past 4000 years, a period that seems to include part of the Holocene Thermal Maximum. Notwithstanding this conclusion, climate models project that if anthropogenic greenhouse gas emissions continue, the Greenland temperature would exceed the natural variability of the past 4000 years sometime before the year 2100.

  5. High relative air humidity and continuous light reduce stomata functionality by affecting the ABA regulation in rose leaves.

    PubMed

    Arve, Louise E; Terfa, Meseret T; Gislerød, Hans Ragnar; Olsen, Jorunn E; Torre, Sissel

    2013-02-01

    Plants developed under high (90%) relative air humidity (RH) have previously been shown to have large, malfunctioning stomata, which results in high water loss during desiccation and reduced dark induced closure. Stomatal movement is to a large extent regulated by abscisic acid (ABA). It has therefore been proposed that low ABA levels contribute to the development of malfunctioning stomata. In this study, we investigated the regulation of ABA content in rose leaves, through hormone analysis and β-glucosidase quantification. Compared with high RH, rose plants developed in moderate RH (60%) and 20 h photoperiod contained higher levels of ABA and β-glucosidase activity. Also, the amount of ABA increased during darkness simultaneously as the ABA-glucose ester (GE) levels decreased. In contrast, plants developed under high RH with 20 h photoperiod showed no increase in ABA levels during darkness, and had low β-glucosidase activity converting ABA-GE to ABA. Continuous lighting (24 h) resulted in low levels of β-glucosidase activity irrespective of RH, indicating that a dark period is essential to activate β-glucosidase. Our results provide new insight into the regulation of ABA under different humidities and photoperiods, and clearly show that β-glucosidase is a key enzyme regulating the ABA pool in rose plants. PMID:22812416

  6. Life cycle air quality impacts of conventional and alternative light-duty transportation in the United States

    SciTech Connect

    Tessum, Christopher W.; Hill, Jason D.; Marshall, Julian D.

    2014-12-30

    Commonly considered strategies for reducing the environmental impact of light-duty transportation include using alternative fuels and improving vehicle fuel economy. We evaluate the air quality-related human health impacts of 10 such options, including the use of liquid biofuels, diesel, and compressed natural gas (CNG) in internal combustion engines; the use of electricity from a range of conventional and renewable sources to power electric vehicles (EVs); and the use of hybrid EV technology. Our approach combines spatially, temporally, and chemically detailed life cycle emission inventories; comprehensive, fine-scale state-of-the-science chemical transport modeling; and exposure, concentration–response, and economic health impact modeling for ozone (O3) and fine particulate matter (PM2.5). We find that powering vehicles with corn ethanol or with coal-based or “grid average” electricity increases monetized environmental health impacts by 80% or more relative to using conventional gasoline. Conversely, EVs powered by low-emitting electricity from natural gas, wind, water, or solar power reduce environmental health impacts by 50% or more. Consideration of potential climate change impacts alongside the human health outcomes described here further reinforces the environmental preferability of EVs powered by low-emitting electricity relative to gasoline vehicles.

  7. An efficient dye-sensitized BiOCl photocatalyst for air and water purification under visible light irradiation.

    PubMed

    Li, Guisheng; Jiang, Bo; Xiao, Shuning; Lian, Zichao; Zhang, Dieqing; Yu, Jimmy C; Li, Hexing

    2014-08-01

    A photosensitized BiOCl catalyst was found to be effective for photocatalytic water purification and air remediation under visible light irradiation (λ > 420 nm). Prepared by a solvothermal method, the BiOCl crystals possessed a 3D hierarchical spherical structure with the highly active facets exposed. When sensitized by Rhodamine B (RhB), the photocatalyst system was more active than N-doped TiO2 for breaking down 4-chlorophenol (4-CP, 200 ppm) and nitric monoxide (NO, 500 ppb). The high activity could be attributed to the hierarchical structure (supplying feasible reaction tunnels for adsorption and transition of reactants or products) and the efficient exposure of the {001} facets. The former provides an enriched oxygen atom density that promotes adsorption of cationic dye RhB, and creates an oxygen vacancy state. The HO˙ and ˙O2(-) radicals produced from the injected electrons from the excited dye molecule (RhB*) into the conduction band of BiOCl were responsible for the excellent photocatalytic performance of the RhB-BiOCl system.

  8. Life cycle air quality impacts of conventional and alternative light-duty transportation in the United States

    PubMed Central

    Hill, Jason D.; Marshall, Julian D.

    2014-01-01

    Commonly considered strategies for reducing the environmental impact of light-duty transportation include using alternative fuels and improving vehicle fuel economy. We evaluate the air quality-related human health impacts of 10 such options, including the use of liquid biofuels, diesel, and compressed natural gas (CNG) in internal combustion engines; the use of electricity from a range of conventional and renewable sources to power electric vehicles (EVs); and the use of hybrid EV technology. Our approach combines spatially, temporally, and chemically detailed life cycle emission inventories; comprehensive, fine-scale state-of-the-science chemical transport modeling; and exposure, concentration–response, and economic health impact modeling for ozone (O3) and fine particulate matter (PM2.5). We find that powering vehicles with corn ethanol or with coal-based or “grid average” electricity increases monetized environmental health impacts by 80% or more relative to using conventional gasoline. Conversely, EVs powered by low-emitting electricity from natural gas, wind, water, or solar power reduce environmental health impacts by 50% or more. Consideration of potential climate change impacts alongside the human health outcomes described here further reinforces the environmental preferability of EVs powered by low-emitting electricity relative to gasoline vehicles. PMID:25512510

  9. Life cycle air quality impacts of conventional and alternative light-duty transportation in the United States.

    PubMed

    Tessum, Christopher W; Hill, Jason D; Marshall, Julian D

    2014-12-30

    Commonly considered strategies for reducing the environmental impact of light-duty transportation include using alternative fuels and improving vehicle fuel economy. We evaluate the air quality-related human health impacts of 10 such options, including the use of liquid biofuels, diesel, and compressed natural gas (CNG) in internal combustion engines; the use of electricity from a range of conventional and renewable sources to power electric vehicles (EVs); and the use of hybrid EV technology. Our approach combines spatially, temporally, and chemically detailed life cycle emission inventories; comprehensive, fine-scale state-of-the-science chemical transport modeling; and exposure, concentration-response, and economic health impact modeling for ozone (O3) and fine particulate matter (PM2.5). We find that powering vehicles with corn ethanol or with coal-based or "grid average" electricity increases monetized environmental health impacts by 80% or more relative to using conventional gasoline. Conversely, EVs powered by low-emitting electricity from natural gas, wind, water, or solar power reduce environmental health impacts by 50% or more. Consideration of potential climate change impacts alongside the human health outcomes described here further reinforces the environmental preferability of EVs powered by low-emitting electricity relative to gasoline vehicles. PMID:25512510

  10. An efficient dye-sensitized BiOCl photocatalyst for air and water purification under visible light irradiation.

    PubMed

    Li, Guisheng; Jiang, Bo; Xiao, Shuning; Lian, Zichao; Zhang, Dieqing; Yu, Jimmy C; Li, Hexing

    2014-08-01

    A photosensitized BiOCl catalyst was found to be effective for photocatalytic water purification and air remediation under visible light irradiation (λ > 420 nm). Prepared by a solvothermal method, the BiOCl crystals possessed a 3D hierarchical spherical structure with the highly active facets exposed. When sensitized by Rhodamine B (RhB), the photocatalyst system was more active than N-doped TiO2 for breaking down 4-chlorophenol (4-CP, 200 ppm) and nitric monoxide (NO, 500 ppb). The high activity could be attributed to the hierarchical structure (supplying feasible reaction tunnels for adsorption and transition of reactants or products) and the efficient exposure of the {001} facets. The former provides an enriched oxygen atom density that promotes adsorption of cationic dye RhB, and creates an oxygen vacancy state. The HO˙ and ˙O2(-) radicals produced from the injected electrons from the excited dye molecule (RhB*) into the conduction band of BiOCl were responsible for the excellent photocatalytic performance of the RhB-BiOCl system. PMID:24934740

  11. Life cycle air quality impacts of conventional and alternative light-duty transportation in the United States.

    PubMed

    Tessum, Christopher W; Hill, Jason D; Marshall, Julian D

    2014-12-30

    Commonly considered strategies for reducing the environmental impact of light-duty transportation include using alternative fuels and improving vehicle fuel economy. We evaluate the air quality-related human health impacts of 10 such options, including the use of liquid biofuels, diesel, and compressed natural gas (CNG) in internal combustion engines; the use of electricity from a range of conventional and renewable sources to power electric vehicles (EVs); and the use of hybrid EV technology. Our approach combines spatially, temporally, and chemically detailed life cycle emission inventories; comprehensive, fine-scale state-of-the-science chemical transport modeling; and exposure, concentration-response, and economic health impact modeling for ozone (O3) and fine particulate matter (PM2.5). We find that powering vehicles with corn ethanol or with coal-based or "grid average" electricity increases monetized environmental health impacts by 80% or more relative to using conventional gasoline. Conversely, EVs powered by low-emitting electricity from natural gas, wind, water, or solar power reduce environmental health impacts by 50% or more. Consideration of potential climate change impacts alongside the human health outcomes described here further reinforces the environmental preferability of EVs powered by low-emitting electricity relative to gasoline vehicles.

  12. Life cycle air quality impacts of conventional and alternative light-duty transportation in the United States

    DOE PAGES

    Tessum, Christopher W.; Hill, Jason D.; Marshall, Julian D.

    2014-12-30

    Commonly considered strategies for reducing the environmental impact of light-duty transportation include using alternative fuels and improving vehicle fuel economy. We evaluate the air quality-related human health impacts of 10 such options, including the use of liquid biofuels, diesel, and compressed natural gas (CNG) in internal combustion engines; the use of electricity from a range of conventional and renewable sources to power electric vehicles (EVs); and the use of hybrid EV technology. Our approach combines spatially, temporally, and chemically detailed life cycle emission inventories; comprehensive, fine-scale state-of-the-science chemical transport modeling; and exposure, concentration–response, and economic health impact modeling for ozonemore » (O3) and fine particulate matter (PM2.5). We find that powering vehicles with corn ethanol or with coal-based or “grid average” electricity increases monetized environmental health impacts by 80% or more relative to using conventional gasoline. Conversely, EVs powered by low-emitting electricity from natural gas, wind, water, or solar power reduce environmental health impacts by 50% or more. Consideration of potential climate change impacts alongside the human health outcomes described here further reinforces the environmental preferability of EVs powered by low-emitting electricity relative to gasoline vehicles.« less

  13. Light propagation characteristics in photonic crystal fibers with α-power profiles of air hole diameter distributions and their application to fiber collimator

    NASA Astrophysics Data System (ADS)

    Yokota, Hirohisa; Higuchi, Keiichi; Imai, Yoh

    2016-08-01

    Light propagation characteristics in photonic crystal fibers (PCFs) with α-power profiles of air hole diameter distributions were theoretically investigated. It was clarified that the intensity peak of the beam propagating in the PCF with Gaussian beam excitation varied periodically with little power attenuation. It was found that the envelope of the periodic intensity variation depended on α. We theoretically demonstrated that the PCF with the α-power profile of the air hole diameter distribution could be applied to a collimator for a conventional PCF with uniform air holes in Gaussian beam excitation to reduce coupling loss, where a PCF of appropriate length with the α-power air hole diameter distribution was spliced to a conventional PCF. It was also found that the coupling efficiency was higher for a larger α.

  14. Unraveling Surface Plasmon Decay in Core-Shell Nanostructures toward Broadband Light-Driven Catalytic Organic Synthesis.

    PubMed

    Huang, Hao; Zhang, Lei; Lv, Zhiheng; Long, Ran; Zhang, Chao; Lin, Yue; Wei, Kecheng; Wang, Chengming; Chen, Lu; Li, Zhi-Yuan; Zhang, Qun; Luo, Yi; Xiong, Yujie

    2016-06-01

    Harnessing surface plasmon of metal nanostructures to promote catalytic organic synthesis holds great promise in solar-to-chemical energy conversion. High conversion efficiency relies not only on broadening the absorption spectrum but on coupling the harvested energy into chemical reactions. Such coupling undergoes hot-electron transfer and photothermal conversion during the decay of surface plasmon; however, the two plasmonic effects are unfortunately entangled, making their individual roles still under debate. Here, we report that in a model system of bimetallic Au-Pd core-shell nanostructures the two effects can be disentangled through tailoring the shell thickness at atomic-level precision. As demonstrated by our ultrafast absorption spectroscopy characterizations, the achieved tunability of the two effects in a model reaction of Pd-catalyzed organic hydrogenation offers a knob for enhancing energy coupling. In addition, the two intrinsic plasmonic modes at 400-700 and 700-1000 nm in the bar-shaped nanostructures allow for utilizing photons to a large extent in full solar spectrum. This work establishes a paradigmatic guidance toward designing plasmonic-catalytic nanomaterials for enhanced solar-to-chemical energy conversion.

  15. Pathways for energy transfer in the core light-harvesting complexes CP43 and CP47 of photosystem II.

    PubMed

    de Weerd, Frank L; van Stokkum, Ivo H M; van Amerongen, Herbert; Dekker, Jan P; van Grondelle, Rienk

    2002-03-01

    The pigment-protein complexes CP43 and CP47 transfer excitation energy from the peripheral antenna of photosystem II toward the photochemical reaction center. We measured the excitation dynamics of the chlorophylls in isolated CP43 and CP47 complexes at 77 K by time-resolved absorbance-difference and fluorescence spectroscopy. The spectral relaxation appeared to occur with rates of 0.2-0.4 ps and 2-3 ps in both complexes, whereas an additional relaxation of 17 ps was observed only in CP47. Using the 3.8-A crystal structure of the photosystem II core complex from Synechococcus elongatus (A. Zouni, H.-T. Witt, J. Kern, P. Fromme, N. Krauss, W. Saenger, and P. Orth, 2001, Nature, 409:739-743), excitation energy transfer kinetics were calculated and a Monte Carlo simulation of the absorption spectra was performed. In both complexes, the rate of 0.2-0.4 ps can be ascribed to excitation energy transfer within a layer of chlorophylls near the stromal side of the membrane, and the slower 2-3-ps process to excitation energy transfer to the calculated lowest excitonic state. We conclude that excitation energy transfer within CP43 and CP47 is fast and does not contribute significantly to the well-known slow trapping of excitation energy in photosystem II.

  16. A visible-light-driven core-shell like Ag2S@Ag2CO3 composite photocatalyst with high performance in pollutants degradation.

    PubMed

    Yu, Changlin; Wei, Longfu; Zhou, Wanqin; Dionysiou, Dionysios D; Zhu, Lihua; Shu, Qing; Liu, Hong

    2016-08-01

    A series of Ag2S-Ag2CO3 (4%, 8%, 16%, 32% and 40% Ag2S), Ag2CO3@Ag2S (32%Ag2S) and Ag2S@Ag2CO3 (32%Ag2S) composite photocatalysts were fabricated by coprecipitation or successive precipitation reaction. The obtained catalysts were analyzed by N2 physical adsorption, powder X-ray diffraction, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, UV-vis diffuse reflectance spectroscopy and photocurrent test. Under visible light irradiation, the influences of Ag2S content and core-shell property on photocatalytic activity and stability were evaluated in studies focused on the degradation of methyl orange (MO) dye, phenol, and bisphenol A. Results showed that excellent photocatalytic performance was obtained over Ag2S/Ag2CO3 composite photocatalysts with respect to Ag2S and Ag2CO3. With optimal content of Ag2S (32 wt%), the Ag2S-Ag2CO3 showed the highest photocatalytic degradation efficiency. Moreover, the structured property of Ag2S/Ag2CO3 greatly influenced the activity. Compared with Ag2S-Ag2CO3 and Ag2CO3@Ag2S, core-shell like Ag2S@Ag2CO3 demonstrated the highest activity and stability. The main reason for the boosting of photocatalytic performance was due to the formation of Ag2S/Ag2CO3 well contacted interface and unique electron structures. Ag2S/Ag2CO3 interface could significantly increase the separation efficiency of the photo-generated electrons (e(-)) and holes (h(+)), and production of OH radicals. More importantly, the low solubility of Ag2S shell could effectively protect the core of Ag2CO3, which further guarantees the stability of Ag2CO3. PMID:27236845

  17. Core-shell InGaN/GaN nanowire light emitting diodes analyzed by electron beam induced current microscopy and cathodoluminescence mapping.

    PubMed

    Tchernycheva, M; Neplokh, V; Zhang, H; Lavenus, P; Rigutti, L; Bayle, F; Julien, F H; Babichev, A; Jacopin, G; Largeau, L; Ciechonski, R; Vescovi, G; Kryliouk, O

    2015-07-21

    We report on the electron beam induced current (EBIC) microscopy and cathodoluminescence (CL) characterization correlated with compositional analysis of light emitting diodes based on core/shell InGaN/GaN nanowire arrays. The EBIC mapping of cleaved fully operational devices allows to probe the electrical properties of the active region with a nanoscale resolution. In particular, the electrical activity of the p-n junction on the m-planes and on the semi-polar planes of individual nanowires is assessed in top view and cross-sectional geometries. The EBIC maps combined with CL characterization demonstrate the impact of the compositional gradients along the wire axis on the electrical and optical signals: the reduction of the EBIC signal toward the nanowire top is accompanied by an increase of the CL intensity. This effect is interpreted as a consequence of the In and Al gradients in the quantum well and in the electron blocking layer, which influence the carrier extraction efficiency. The interface between the nanowire core and the radially grown layer is shown to produce in some cases a transitory EBIC signal. This observation is explained by the presence of charged traps at this interface, which can be saturated by electron irradiation.

  18. Synthesis, characterization and visible-light driven photocatalysis by differently structured CdS/ZnS sandwich and core-shell nanocomposites

    NASA Astrophysics Data System (ADS)

    Qutub, Nida; Pirzada, Bilal Masood; Umar, Khalid; Mehraj, Owais; Muneer, M.; Sabir, Suhail

    2015-11-01

    CdS/ZnS sandwich and core-shell nanocomposites were synthesized by a simple and modified Chemical Precipitation method under ambient conditions. The synthesized composites were characterized by XRD, SEM, TEM, EDAX and FTIR. Optical properties were analyzed by UV-vis. Spectroscopy and the photoluminescence study was done to monitor the recombination of photo-generated charge-carriers. Thermal stability of the synthesized composites was analyzed by Thermal Gravimetric Analysis (TGA). XRD revealed the formation of nanocomposites as mixed diffraction peaks were observed in the XRD pattern. SEM and TEM showed the morphology of the nanocomposites particles and their fine particle size. EDAX revealed the appropriate molar ratios exhibited by the constituent elements in the composites and FTIR gave some characteristic peaks which indicated the formation of CdS/ZnS nanocomposites. Electrochemical Impedance Spectroscopy was done to study charge transfer properties along the nanocomposites. Photocatalytic properties of the synthesized composites were monitored by the photocatalytic kinetic study of Acid Blue dye and p-chlorophenol under visible light irradiation. Results revealed the formation of stable core-shell nanocomposites and their efficient photocatalytic properties.

  19. Strongly polarized quantum-dot-like light emitters embedded in GaAs/GaNAs core/shell nanowires.

    PubMed

    Filippov, S; Jansson, M; Stehr, J E; Palisaitis, J; Persson, P O Å; Ishikawa, F; Chen, W M; Buyanova, I A

    2016-09-21

    Recent developments in fabrication techniques and extensive investigations of the physical properties of III-V semiconductor nanowires (NWs), such as GaAs NWs, have demonstrated their potential for a multitude of advanced electronic and photonics applications. Alloying of GaAs with nitrogen can further enhance the performance and extend the device functionality via intentional defects and heterostructure engineering in GaNAs and GaAs/GaNAs coaxial NWs. In this work, it is shown that incorporation of nitrogen in GaAs NWs leads to formation of three-dimensional confining potentials caused by short-range fluctuations in the nitrogen composition, which are superimposed on long-range alloy disorder. The resulting localized states exhibit a quantum-dot like electronic structure, forming optically active states in the GaNAs shell. By directly correlating the structural and optical properties of individual NWs, it is also shown that formation of the localized states is efficient in pure zinc-blende wires and is further facilitated by structural polymorphism. The light emission from these localized states is found to be spectrally narrow (∼50-130 μeV) and is highly polarized (up to 100%) with the preferable polarization direction orthogonal to the NW axis, suggesting a preferential orientation of the localization potential. These properties of self-assembled nano-emitters embedded in the GaNAs-based nanowire structures may be attractive for potential optoelectronic applications. PMID:27537077

  20. Strongly polarized quantum-dot-like light emitters embedded in GaAs/GaNAs core/shell nanowires.

    PubMed

    Filippov, S; Jansson, M; Stehr, J E; Palisaitis, J; Persson, P O Å; Ishikawa, F; Chen, W M; Buyanova, I A

    2016-09-21

    Recent developments in fabrication techniques and extensive investigations of the physical properties of III-V semiconductor nanowires (NWs), such as GaAs NWs, have demonstrated their potential for a multitude of advanced electronic and photonics applications. Alloying of GaAs with nitrogen can further enhance the performance and extend the device functionality via intentional defects and heterostructure engineering in GaNAs and GaAs/GaNAs coaxial NWs. In this work, it is shown that incorporation of nitrogen in GaAs NWs leads to formation of three-dimensional confining potentials caused by short-range fluctuations in the nitrogen composition, which are superimposed on long-range alloy disorder. The resulting localized states exhibit a quantum-dot like electronic structure, forming optically active states in the GaNAs shell. By directly correlating the structural and optical properties of individual NWs, it is also shown that formation of the localized states is efficient in pure zinc-blende wires and is further facilitated by structural polymorphism. The light emission from these localized states is found to be spectrally narrow (∼50-130 μeV) and is highly polarized (up to 100%) with the preferable polarization direction orthogonal to the NW axis, suggesting a preferential orientation of the localization potential. These properties of self-assembled nano-emitters embedded in the GaNAs-based nanowire structures may be attractive for potential optoelectronic applications.

  1. Tunable light emission by exciplex state formation between hybrid halide perovskite and core/shell quantum dots: Implications in advanced LEDs and photovoltaics

    PubMed Central

    Sanchez, Rafael S.; de la Fuente, Mauricio Solis; Suarez, Isaac; Muñoz-Matutano, Guillermo; Martinez-Pastor, Juan P.; Mora-Sero, Ivan

    2016-01-01

    We report the first observation of exciplex state electroluminescence due to carrier injection between the hybrid lead halide perovskite (MAPbI3–xClx) and quantum dots (core/shell PbS/CdS). Single layers of perovskite (PS) and quantum dots (QDs) have been produced by solution processing methods, and their photoluminescent properties are compared to those of bilayer samples in both PS/QD and QD/PS configurations. Exciplex emission at lower energies than the band gap of both PS and QD has been detected. The exciplex emission wavelength of this mixed system can be simply tuned by controlling the QD size. Light-emitting diodes (LEDs) have been fabricated using those configurations, which provide light emission with considerably low turn-on potential. The “color” of the LED can also be tuned by controlling the applied bias. The presence of the exciplex state PS and QDs opens up a broad range of possibilities with important implications not only in tunable LEDs but also in the preparation of intermediate band gap photovoltaic devices with the potentiality of surpassing the Shockley-Queisser limit. PMID:26844299

  2. Tunable light emission by exciplex state formation between hybrid halide perovskite and core/shell quantum dots: Implications in advanced LEDs and photovoltaics.

    PubMed

    Sanchez, Rafael S; de la Fuente, Mauricio Solis; Suarez, Isaac; Muñoz-Matutano, Guillermo; Martinez-Pastor, Juan P; Mora-Sero, Ivan

    2016-01-01

    We report the first observation of exciplex state electroluminescence due to carrier injection between the hybrid lead halide perovskite (MAPbI3-xClx) and quantum dots (core/shell PbS/CdS). Single layers of perovskite (PS) and quantum dots (QDs) have been produced by solution processing methods, and their photoluminescent properties are compared to those of bilayer samples in both PS/QD and QD/PS configurations. Exciplex emission at lower energies than the band gap of both PS and QD has been detected. The exciplex emission wavelength of this mixed system can be simply tuned by controlling the QD size. Light-emitting diodes (LEDs) have been fabricated using those configurations, which provide light emission with considerably low turn-on potential. The "color" of the LED can also be tuned by controlling the applied bias. The presence of the exciplex state PS and QDs opens up a broad range of possibilities with important implications not only in tunable LEDs but also in the preparation of intermediate band gap photovoltaic devices with the potentiality of surpassing the Shockley-Queisser limit. PMID:26844299

  3. Tunable light emission by exciplex state formation between hybrid halide perovskite and core/shell quantum dots: Implications in advanced LEDs and photovoltaics.

    PubMed

    Sanchez, Rafael S; de la Fuente, Mauricio Solis; Suarez, Isaac; Muñoz-Matutano, Guillermo; Martinez-Pastor, Juan P; Mora-Sero, Ivan

    2016-01-01

    We report the first observation of exciplex state electroluminescence due to carrier injection between the hybrid lead halide perovskite (MAPbI3-xClx) and quantum dots (core/shell PbS/CdS). Single layers of perovskite (PS) and quantum dots (QDs) have been produced by solution processing methods, and their photoluminescent properties are compared to those of bilayer samples in both PS/QD and QD/PS configurations. Exciplex emission at lower energies than the band gap of both PS and QD has been detected. The exciplex emission wavelength of this mixed system can be simply tuned by controlling the QD size. Light-emitting diodes (LEDs) have been fabricated using those configurations, which provide light emission with considerably low turn-on potential. The "color" of the LED can also be tuned by controlling the applied bias. The presence of the exciplex state PS and QDs opens up a broad range of possibilities with important implications not only in tunable LEDs but also in the preparation of intermediate band gap photovoltaic devices with the potentiality of surpassing the Shockley-Queisser limit.

  4. Warm White Light Emitting Diodes with Gelatin-Coated AgInS2/ZnS Core/Shell Quantum Dots.

    PubMed

    Kang, Xiaojiao; Yang, Yanchun; Wang, Lan; Wei, Song; Pan, Daocheng

    2015-12-23

    Cadmium-free and water-soluble AgInS2/ZnS core/shell quantum dots (QDs) with a cost of 2.5 $/g are synthesized in an electric pressure cooker. The QD powders with different Ag/In ratios exhibit bright yellow, orange, and orange-red luminescence under UV light. Their absolute photoluminescence quantum yields (PLQYs) can reach as high as 50.5, 57, and 52%, respectively. Because gelatin is used as the capping agent, the concentrated QDs/gelatin solution can be directly utilized as phosphor for the fabrication of white light-emitting diodes (LEDs) by a simple drop-drying process without the need of resin package. Warm-white LEDs are obtained by combining orange-emitting QDs with blue InGaN chip. As-fabricated warm-white LED exhibits a luminous efficacy of 39.85 lm/W, a correlated color temperature (CCT) of 2634 K and a color rendering index (CRI) of 71 at a drive current of 20 mA. Furthermore, the electroluminescence (EL) stability of LED device and thermal stability of as-prepared QDs are evaluated. PMID:26629791

  5. Rapid phase adjustment of melatonin and core body temperature rhythms following a 6-h advance of the light/dark cycle in the horse

    PubMed Central

    Murphy, Barbara A; Elliott, Jeffrey A; Sessions, Dawn R; Vick, Mandi M; Kennedy, Erin L; Fitzgerald, Barry P

    2007-01-01

    Background Rapid displacement across multiple time zones results in a conflict between the new cycle of light and dark and the previously entrained program of the internal circadian clock, a phenomenon known as jet lag. In humans, jet lag is often characterized by malaise, appetite loss, fatigue, disturbed sleep and performance deficit, the consequences of which are of particular concern to athletes hoping to perform optimally at an international destination. As a species renowned for its capacity for athletic performance, the consequences of jet lag are also relevant for the horse. However, the duration and severity of jet lag related circadian disruption is presently unknown in this species. We investigated the rates of re-entrainment of serum melatonin and core body temperature (BT) rhythms following an abrupt 6-h phase advance of the LD cycle in the horse. Methods Six healthy, 2 yr old mares entrained to a 12 h light/12 h dark (LD 12:12) natural photoperiod were housed in a light-proofed barn under a lighting schedule that mimicked the external LD cycle. Following baseline sampling on Day 0, an advance shift of the LD cycle was accomplished by ending the subsequent dark period 6 h early. Blood sampling for serum melatonin analysis and BT readings were taken at 3-h intervals for 24 h on alternate days for 11 days. Disturbances to the subsequent melatonin and BT 24-h rhythms were assessed using repeated measures ANOVA and analysis of Cosine curve fitting parameters. Results We demonstrate that the equine melatonin rhythm re-entrains rapidly to a 6-h phase advance of an LD12:12 photocycle. The phase shift in melatonin was fully complete on the first day of the new schedule and rhythm phase and waveform were stable thereafter. In comparison, the advance in the BT rhythm was achieved by the third day, however BT rhythm waveform, especially its mesor, was altered for many days following the LD shift. Conclusion Aside from the temperature rhythm disruption, rapid

  6. Planetary Nebulae and their parent stellar populations. Tracing the mass assembly of M87 and Intracluster light in the Virgo cluster core

    NASA Astrophysics Data System (ADS)

    Arnaboldi, Magda; Longobardi, Alessia; Gerhard, Ortwin

    2016-08-01

    The diffuse extended outer regions of galaxies are hard to study because they are faint, with typical surface brightness of 1% of the dark night sky. We can tackle this problem by using resolved star tracers which remain visible at large distances from the galaxy centers. This article describes the use of Planetary Nebulae as tracers and the calibration of their properties as indicators of the star formation history, mean age and metallicity of the parent stars in the Milky Way and Local Group galaxies. We then report on the results from a deep, extended, planetary nebulae survey in a 0.5 deg2 region centered on the brightest cluster galaxy NGC 4486 (M87) in the Virgo cluster core, carried out with SuprimeCam@Subaru and FLAMES-GIRAFFE@VLT. Two planetary nebulae populations are identified out to 150 kpc distance from the center of M87. One population is associated with the M87 halo and the second one with the intracluster light in the Virgo cluster core. They have different line-of-sight velocity and spatial distributions, as well as different planetary nebulae specific frequencies and luminosity functions. The intracluster planetary nebulae in the surveyed region correspond to a luminosity of four times the luminosity of the Large Magellanic Cloud. The M87 halo planetary nebulae trace an older, more metal-rich, parent stellar population. A substructure detected in the projected phase-space of the line-of-sight velocity vs. major axis distance for the M87 halo planetary nebulae provides evidence for the recent accretion event of a satellite galaxy with luminosity twice that of M33. The satellite stars were tidally stripped about 1 Gyr ago, and reached apocenter at a major axis distance of 60-90 kpc from the center of M87. The M87 halo is still growing significantly at the distances where the substructure is detected.

  7. Temperature Dependence of Light-Induced Absorbance Changes Associated with Chlorophyll Photooxidation in Manganese-Depleted Core Complexes of Photosystem II.

    PubMed

    Zabelin, A A; Shkuropatova, V A; Shkuropatov, A Ya; Shuvalov, V A

    2015-10-01

    Mid-infrared (4500-1150 cm(-1)) absorbance changes induced by continuous illumination of Mn-depleted core complexes of photosystem II (PSII) from spinach in the presence of exogenous electron acceptors (potassium ferricyanide and silicomolybdate) were studied by FTIR difference spectroscopy in the temperature range 100-265 K. The FTIR difference spectrum for photooxidation of the chlorophyll dimer P680 was determined from the set of signals associated with oxidation of secondary electron donors (β-carotene, chlorophyll) and reduction of the primary quinone QA. On the basis of analysis of the temperature dependence of the P680(+)/P680 FTIR spectrum, it was concluded that frequencies of 13(1)-keto-C=O stretching modes of neutral chlorophyll molecules PD1 and PD2, which constitute P680, are similar to each other, being located at ~1700 cm(-1). This together with considerable difference between the stretching mode frequencies of keto groups of PD1(+) and PD2(+) cations (1724 and 1709 cm(-1), respectively) is in agreement with a literature model (Okubo et al. (2007) Biochemistry, 46, 4390-4397) suggesting that the positive charge in the P680(+) dimer is mainly localized on one of the two chlorophyll molecules. A partial delocalization of the charge between the PD1 and PD2 molecules in P680(+) is supported by the presence of a characteristic electronic intervalence band at ~3000 cm(-1). It is shown that a bleaching band at 1680 cm(-1) in the P680(+)/P680 FTIR spectrum does not belong to P680. A possible origin of this band is discussed, taking into account the temperature dependence (100-265 K) of light-induced absorbance changes of PSII core complexes in the visible spectral region from 620 to 720 nm.

  8. Temperature Dependence of Light-Induced Absorbance Changes Associated with Chlorophyll Photooxidation in Manganese-Depleted Core Complexes of Photosystem II.

    PubMed

    Zabelin, A A; Shkuropatova, V A; Shkuropatov, A Ya; Shuvalov, V A

    2015-10-01

    Mid-infrared (4500-1150 cm(-1)) absorbance changes induced by continuous illumination of Mn-depleted core complexes of photosystem II (PSII) from spinach in the presence of exogenous electron acceptors (potassium ferricyanide and silicomolybdate) were studied by FTIR difference spectroscopy in the temperature range 100-265 K. The FTIR difference spectrum for photooxidation of the chlorophyll dimer P680 was determined from the set of signals associated with oxidation of secondary electron donors (β-carotene, chlorophyll) and reduction of the primary quinone QA. On the basis of analysis of the temperature dependence of the P680(+)/P680 FTIR spectrum, it was concluded that frequencies of 13(1)-keto-C=O stretching modes of neutral chlorophyll molecules PD1 and PD2, which constitute P680, are similar to each other, being located at ~1700 cm(-1). This together with considerable difference between the stretching mode frequencies of keto groups of PD1(+) and PD2(+) cations (1724 and 1709 cm(-1), respectively) is in agreement with a literature model (Okubo et al. (2007) Biochemistry, 46, 4390-4397) suggesting that the positive charge in the P680(+) dimer is mainly localized on one of the two chlorophyll molecules. A partial delocalization of the charge between the PD1 and PD2 molecules in P680(+) is supported by the presence of a characteristic electronic intervalence band at ~3000 cm(-1). It is shown that a bleaching band at 1680 cm(-1) in the P680(+)/P680 FTIR spectrum does not belong to P680. A possible origin of this band is discussed, taking into account the temperature dependence (100-265 K) of light-induced absorbance changes of PSII core complexes in the visible spectral region from 620 to 720 nm. PMID:26567571

  9. Air-Stable, Near- to Mid-Infrared Emitting Solids of PbTe/CdTe Core-Shell Colloidal quantum dots.

    PubMed

    Protesescu, Loredana; Zünd, Tanja; Bodnarchuk, Maryna I; Kovalenko, Maksym V

    2016-03-01

    Light emitters and detectors operating in the near- and mid-infrared spectral regions are important to many applications, such as telecommunications, high-resolution gas analysis, atmospheric pollution monitoring, medical diagnostics, and night vision. Various lead chalcogenides (binary, ternary, and quaternary alloys) in the form of quantum dots (QDs) or quantum wells provide narrow bandgap energies that cover the broad infrared region corresponding to wavelengths of 1-30 μm. Here, we report an inexpensive, all-solution-based synthesis strategy to thin-film solids consisting of 5-16 nm PbTe QDs encapsulated by CdTe shells. Colloidally synthesized PbTe QDs were first converted into core-shell PbTe/CdTe QDs, and then deposited as thin films. The subsequent fusion of the CdTe shells is achieved by ligand removal and annealing in the presence of CdCl2 . Contrary to highly unstable bare PbTe QDs, PbTe/CdTe QD solids exhibit bright and stable near- to mid-infrared emission at wavelengths of 1-3 μm, which is also retained upon prolonged storage at ambient conditions for one year.

  10. Air-Stable, Near- to Mid-Infrared Emitting Solids of PbTe/CdTe Core-Shell Colloidal quantum dots.

    PubMed

    Protesescu, Loredana; Zünd, Tanja; Bodnarchuk, Maryna I; Kovalenko, Maksym V

    2016-03-01

    Light emitters and detectors operating in the near- and mid-infrared spectral regions are important to many applications, such as telecommunications, high-resolution gas analysis, atmospheric pollution monitoring, medical diagnostics, and night vision. Various lead chalcogenides (binary, ternary, and quaternary alloys) in the form of quantum dots (QDs) or quantum wells provide narrow bandgap energies that cover the broad infrared region corresponding to wavelengths of 1-30 μm. Here, we report an inexpensive, all-solution-based synthesis strategy to thin-film solids consisting of 5-16 nm PbTe QDs encapsulated by CdTe shells. Colloidally synthesized PbTe QDs were first converted into core-shell PbTe/CdTe QDs, and then deposited as thin films. The subsequent fusion of the CdTe shells is achieved by ligand removal and annealing in the presence of CdCl2 . Contrary to highly unstable bare PbTe QDs, PbTe/CdTe QD solids exhibit bright and stable near- to mid-infrared emission at wavelengths of 1-3 μm, which is also retained upon prolonged storage at ambient conditions for one year. PMID:26676076

  11. A core/shell/satellite anticancer platform for 808 NIR light-driven multimodal imaging and combined chemo-/photothermal therapy

    NASA Astrophysics Data System (ADS)

    Yang, Guixin; Lv, Ruichan; He, Fei; Qu, Fengyu; Gai, Shili; Du, Shaokang; Wei, Zibo; Yang, Piaoping

    2015-08-01

    In this contribution, a novel multifunctional anti-cancer nanoplatform has been firstly constructed by conjugating a photothermal agent (CuS nanoparticles) and a cancer cell target agent (folic acid, FA) onto the surface of mesoporous silica coated core-shell-shell up-conversion nanoparticles (UCNPs). It was found that the doxorubicin (DOX) loaded system exhibits obvious pH and NIR-responsive release behaviour and the drug can be targetedly delivered to the cancer cells by a receptor mediated endocytosis manner. Furthermore, both photothermal therapy (PTT) and chemotherapy can be triggered simultaneously by a single 808 nm near infrared (NIR) light source, thus leading to a synergistic effect. The combined chemo- and NIR photothermal therapy can significantly improve the therapeutic efficacy compared to any single therapy, which has been evidenced by both in vitro and in vivo results. Besides, due to the doped rare earth ions, the platform also exhibits good up-conversion luminescence (UCL), computed tomography (CT) and magnetic resonance imaging (MRI) properties. Based on the excellent multimodal imaging and anti-tumor properties, the multifunctional nanoplatform should be a promising candidate for imaging-guided anti-cancer therapy.In this contribution, a novel multifunctional anti-cancer nanoplatform has been firstly constructed by conjugating a photothermal agent (CuS nanoparticles) and a cancer cell target agent (folic acid, FA) onto the surface of mesoporous silica coated core-shell-shell up-conversion nanoparticles (UCNPs). It was found that the doxorubicin (DOX) loaded system exhibits obvious pH and NIR-responsive release behaviour and the drug can be targetedly delivered to the cancer cells by a receptor mediated endocytosis manner. Furthermore, both photothermal therapy (PTT) and chemotherapy can be triggered simultaneously by a single 808 nm near infrared (NIR) light source, thus leading to a synergistic effect. The combined chemo- and NIR photothermal

  12. Effects of air current speed, light intensity and co2 concentration on photosynthesis and transpiration of plant leaves

    NASA Astrophysics Data System (ADS)

    Kitaya, Y.; Tsuruyama, J.; Shibuya, T.; Kiyota, M.

    To obtain basic data for adequate air circulation to promote gas exchange and growth of plants in closed plant culture modules in bioregenerative life support systems in space, the effects of air current speeds less than 0.8 m s-1 on transpiration (Tr) and net photosynthetic rates (Pn) of sweetpotato and barley leaves were determined using a leaf chamber method under different photosynthetic photon flux densities (PPFDs) and CO_2 concentrations. The air current speed inside the leaf chamber was controlled by controlling the input voltages for an air circulation fan. The leaf surface boundary layer resistance was determined by the evaporation rate of wet paper and the water vapor pressure difference between the paper and surrounding air in the leaf chamber. The Tr and Pn of leaves rapidly increased as the air current speed increased from 0.01 to 0.1 m s-1 and gradually increased from 0.1 to 0.8 m s-1. These changes are correspondent to the change of the leaf surface boundary layer resistance. The depression of Tr by low air current speeds was greater than that of Pn. Tr and Pn decreased by 0.5 and 0.7 times, respectively, as the air current speed decreased from 0.8 to 0.01 m s-1. The depressions of Tr and Pn by low air current speeds were most notable at PPFDs of 500 and 250 μmol m-2 s-1, respectively. The air current speeds affected Tr and Pn at a CO_2 concentration of 700 μmol mol-1 as well as at 400 μmol mol-1. The results confirmed the importance of controlling air movement for enhancing Tr and Pn under the relatively high PPFD and elevated CO_2 levels likely in plant culture systems in space.

  13. Core layering

    NASA Astrophysics Data System (ADS)

    Jacobson, S. A.; Rubie, D. C.; Hernlund, J. W.; Morbidelli, A.

    2015-12-01

    We have created a planetary accretion and differentiation model that self-consistently builds and evolves Earth's core. From this model, we show that the core grows stably stratified as the result of rising metal-silicate equilibration temperatures and pressures, which increases the concentrations of light element impurities into each newer core addition. This stable stratification would naturally resist convection and frustrate the onset of a geodynamo, however, late giant impacts could mechanically mix the distinct accreted core layers creating large homogenous regions. Within these regions, a geodynamo may operate. From this model, we interpret the difference between the planetary magnetic fields of Earth and Venus as a difference in giant impact histories. Our planetary accretion model is a numerical N-body integration of the Grand Tack scenario [1]—the most successful terrestrial planet formation model to date [2,3]. Then, we take the accretion histories of Earth-like and Venus-like planets from this model and post-process the growth of each terrestrial planet according to a well-tested planetary differentiation model [4,5]. This model fits Earth's mantle by modifying the oxygen content of the pre-cursor planetesimals and embryos as well as the conditions of metal-silicate equilibration. Other non-volatile major, minor and trace elements included in the model are assumed to be in CI chondrite proportions. The results from this model across many simulated terrestrial planet growth histories are robust. If the kinetic energy delivered by larger impacts is neglected, the core of each planet grows with a strong stable stratification that would significantly impede convection. However, if giant impact mixing is very efficient or if the impact history delivers large impacts late, than the stable stratification can be removed. [1] Walsh et al. Nature 475 (2011) [2] O'Brien et al. Icarus 223 (2014) [3] Jacobson & Morbidelli PTRSA 372 (2014) [4] Rubie et al. EPSL 301

  14. Life cycle air emissions impacts and ownership costs of light-duty vehicles using natural gas as a primary energy source.

    PubMed

    Luk, Jason M; Saville, Bradley A; MacLean, Heather L

    2015-04-21

    This paper aims to comprehensively distinguish among the merits of different vehicles using a common primary energy source. In this study, we consider compressed natural gas (CNG) use directly in conventional vehicles (CV) and hybrid electric vehicles (HEV), and natural gas-derived electricity (NG-e) use in plug-in battery electric vehicles (BEV). This study evaluates the incremental life cycle air emissions (climate change and human health) impacts and life cycle ownership costs of non-plug-in (CV and HEV) and plug-in light-duty vehicles. Replacing a gasoline CV with a CNG CV, or a CNG CV with a CNG HEV, can provide life cycle air emissions impact benefits without increasing ownership costs; however, the NG-e BEV will likely increase costs (90% confidence interval: $1000 to $31 000 incremental cost per vehicle lifetime). Furthermore, eliminating HEV tailpipe emissions via plug-in vehicles has an insignificant incremental benefit, due to high uncertainties, with emissions cost benefits between -$1000 and $2000. Vehicle criteria air contaminants are a relatively minor contributor to life cycle air emissions impacts because of strict vehicle emissions standards. Therefore, policies should focus on adoption of plug-in vehicles in nonattainment regions, because CNG vehicles are likely more cost-effective at providing overall life cycle air emissions impact benefits.

  15. Life cycle air emissions impacts and ownership costs of light-duty vehicles using natural gas as a primary energy source.

    PubMed

    Luk, Jason M; Saville, Bradley A; MacLean, Heather L

    2015-04-21

    This paper aims to comprehensively distinguish among the merits of different vehicles using a common primary energy source. In this study, we consider compressed natural gas (CNG) use directly in conventional vehicles (CV) and hybrid electric vehicles (HEV), and natural gas-derived electricity (NG-e) use in plug-in battery electric vehicles (BEV). This study evaluates the incremental life cycle air emissions (climate change and human health) impacts and life cycle ownership costs of non-plug-in (CV and HEV) and plug-in light-duty vehicles. Replacing a gasoline CV with a CNG CV, or a CNG CV with a CNG HEV, can provide life cycle air emissions impact benefits without increasing ownership costs; however, the NG-e BEV will likely increase costs (90% confidence interval: $1000 to $31 000 incremental cost per vehicle lifetime). Furthermore, eliminating HEV tailpipe emissions via plug-in vehicles has an insignificant incremental benefit, due to high uncertainties, with emissions cost benefits between -$1000 and $2000. Vehicle criteria air contaminants are a relatively minor contributor to life cycle air emissions impacts because of strict vehicle emissions standards. Therefore, policies should focus on adoption of plug-in vehicles in nonattainment regions, because CNG vehicles are likely more cost-effective at providing overall life cycle air emissions impact benefits. PMID:25825338

  16. Comparison of the efficacy of a forced-air warming system and circulating-water mattress on core temperature and post-anesthesia shivering in elderly patients undergoing total knee arthroplasty under spinal anesthesia

    PubMed Central

    Lee, Kyu Chang; Lee, Myeong Jong; Kim, Mi-Na; Kim, Ji-Sub; Lee, Won Sang; Lee, Jung Hwa

    2014-01-01

    Background In the present study, we compared changes in body temperature and the occurrence of shivering in elderly patients undergoing total knee arthroplasty under spinal anesthesia during warming with either a forced-air warming system or a circulating-water mattress. Methods Forty-six patients were randomly assigned to either the forced-air warming system (N = 23) or circulating-water mattress (N = 23) group. Core temperature was recorded using measurements at the tympanic membrane and rectum. In addition, the incidence and intensity of post-anesthesia shivering and verbal analogue score for thermal comfort were simultaneously assessed. Results Core temperature outcomes did not differ between the groups. The incidence (13.0 vs 43.5%, P < 0.05) and intensity (20/2/1/0/0 vs 13/5/3/2/0, P < 0.05) of post-anesthesia shivering was significantly lower in the forced-air system group than in the circulating-water mattress group. Conclusions The circulating-water mattress was as effective as the forced-air warming system for maintaining body temperature. However, the forced-air warming system was superior to the circulating-water mattress in reducing the incidence of post-anesthesia shivering. PMID:24910726

  17. Synthesis of BiVO4@C Core-Shell Structure on Reduced Graphene Oxide with Enhanced Visible-Light Photocatalytic Activity.

    PubMed

    Sun, Zhihua; Li, Chenzhe; Zhu, Shenmin; Cho, Maenghyo; Chen, Zhixin; Cho, Kyeongjae; Liao, Yongliang; Yin, Chao; Zhang, Di

    2015-08-24

    Herein, a facile strategy for the controllable synthesis of BiVO4@C core-shell nanoparticles on reduced graphene oxide (RGO) is reported. The BiVO4 particle size can be controlled in the process by adjusting the volume ratio of glycerol in the sol-gel solution. The glycerol layers adsorbed on BiVO4 (BiVO4@glycerol) made it possible to form hydrogen bonds between BiVO4@glycerol and graphene oxide with the assistance of ultrasound. After thermal treatment, glycerol adsorbed on the BiVO4 particles formed amorphous carbon shells to link the particles and RGO. As a result, the obtained RGO-BiVO4@C nanocomposite showed a five times higher rate in O2 evolution from water under visible-light irradiation. Also, it demonstrated a six times higher photocatalytic performance enhancement than that of pure BiVO4 in the degradation of Rhodamine B. The enhanced performance is attributed to the carbon shells that restrict the growth of BiVO4 , the reduced graphene oxide that improves the electronic conductivity of the composite, and importantly, the bonds formed between the carbon shells and RGO that reduce the recombination loss of photogenerated charges effectively. The strategy is simple, effective, and can be extended to other ternary oxides with controlled size and high performance.

  18. A core/shell/satellite anticancer platform for 808 NIR light-driven multimodal imaging and combined chemo-/photothermal therapy.

    PubMed

    Yang, Guixin; Lv, Ruichan; He, Fei; Qu, Fengyu; Gai, Shili; Du, Shaokang; Wei, Zibo; Yang, Piaoping

    2015-08-28

    In this contribution, a novel multifunctional anti-cancer nanoplatform has been firstly constructed by conjugating a photothermal agent (CuS nanoparticles) and a cancer cell target agent (folic acid, FA) onto the surface of mesoporous silica coated core-shell-shell up-conversion nanoparticles (UCNPs). It was found that the doxorubicin (DOX) loaded system exhibits obvious pH and NIR-responsive release behaviour and the drug can be targetedly delivered to the cancer cells by a receptor mediated endocytosis manner. Furthermore, both photothermal therapy (PTT) and chemotherapy can be triggered simultaneously by a single 808 nm near infrared (NIR) light source, thus leading to a synergistic effect. The combined chemo- and NIR photothermal therapy can significantly improve the therapeutic efficacy compared to any single therapy, which has been evidenced by both in vitro and in vivo results. Besides, due to the doped rare earth ions, the platform also exhibits good up-conversion luminescence (UCL), computed tomography (CT) and magnetic resonance imaging (MRI) properties. Based on the excellent multimodal imaging and anti-tumor properties, the multifunctional nanoplatform should be a promising candidate for imaging-guided anti-cancer therapy. PMID:26220401

  19. Sci—Thur PM: Imaging — 03: A novel Čerenkov detector based on air-spaced light guiding taper for megavoltage x-ray imaging

    SciTech Connect

    Teymurazyan, A; Rowlands, J A; Pang, G

    2014-08-15

    Electronic Portal Imaging Devices (EPIDs) have been used in radiation therapy and are still needed on linear accelerators (Linacs) equipped with kilovoltage cone beam CT (kV-CBCT) or MRI systems. Recently a new concept of a high quantum efficiency (QE) Čerenkov Portal Imaging Device (CPID) for MV x-ray imaging in radiation therapy was introduced. It relies on Čerenkov effect for x-ray detection. The proposed design consisted of a matrix of optical fibres aligned with the incident x-rays and coupled to an active matrix flat panel imager (AMFPI) for image readout. A weakness of such design is that too few Čerenkov light photons reach the AMFPI for each incident x-ray and an AMFPI with an avalanche gain is required. In this work we propose to replace the optical fibers in the CPID with light guides without a cladding layer that are suspended in air. The air between the light guides takes on the role of the cladding layer found in a regular optical fiber. Since air has a significantly lower refractive index, a much superior light collection efficiency is achieved. Our Monte Carlo studies have shown that the modified new CPID has a QE more than an order of magnitude greater than that of current clinical systems and yet a spatial resolution similar to that of current flat-panel based EPIDs. Furthermore it has been demonstrated that the new CPID does not require an avalanche gain in the AMFPI and is quantum noise limited at dose levels corresponding to a single Linac pulse.

  20. The timing of the human circadian clock is accurately represented by the core body temperature rhythm following phase shifts to a three-cycle light stimulus near the critical zone

    NASA Technical Reports Server (NTRS)

    Jewett, M. E.; Duffy, J. F.; Czeisler, C. A.

    2000-01-01

    A double-stimulus experiment was conducted to evaluate the phase of the underlying circadian clock following light-induced phase shifts of the human circadian system. Circadian phase was assayed by constant routine from the rhythm in core body temperature before and after a three-cycle bright-light stimulus applied near the estimated minimum of the core body temperature rhythm. An identical, consecutive three-cycle light stimulus was then applied, and phase was reassessed. Phase shifts to these consecutive stimuli were no different from those obtained in a previous study following light stimuli applied under steady-state conditions over a range of circadian phases similar to those at which the consecutive stimuli were applied. These data suggest that circadian phase shifts of the core body temperature rhythm in response to a three-cycle stimulus occur within 24 h following the end of the 3-day light stimulus and that this poststimulus temperature rhythm accurately reflects the timing of the underlying circadian clock.

  1. Core assembly storage structure

    DOEpatents

    Jones, Jr., Charles E.; Brunings, Jay E.

    1988-01-01

    A structure for the storage of core assemblies from a liquid metal-cooled nuclear reactor. The structure comprises an enclosed housing having a substantially flat horizontal top plate, a bottom plate and substantially vertical wall members extending therebetween. A plurality of thimble members extend downwardly through the top plate. Each thimble member is closed at its bottom end and has an open end adjacent said top plate. Each thimble member has a length and diameter greater than that of the core assembly to be stored therein. The housing is provided with an inlet duct for the admission of cooling air and an exhaust duct for the discharge of air therefrom, such that when hot core assemblies are placed in the thimbles, the heat generated will by convection cause air to flow from the inlet duct around the thimbles and out the exhaust duct maintaining the core assemblies at a safe temperature without the necessity of auxiliary powered cooling equipment.

  2. Magnetically separable {gamma}-Fe{sub 2}O{sub 3}-SiO{sub 2}-Ce-doped TiO{sub 2} core-shell nanocomposites: Fabrication and visible-light-driven photocatalytic activity

    SciTech Connect

    He, Minqiang; Li, Di; Jiang, Deli; Chen, Min

    2012-08-15

    Novel visible-light-induced {gamma}-Fe{sub 2}O{sub 3}-SiO{sub 2}-Ce-doped-TiO{sub 2} core-shell nanocomposite photocatalysts capable of magnetic separation have been synthesized by a facile sol-gel and after-annealing process. The as-obtained core-shell nanocomposite is composed of a central {gamma}-Fe{sub 2}O{sub 3} core with a strong response to external fields, an interlayer of SiO{sub 2}, and an outer layer of Ce-doped TiO{sub 2} nanocrystals. UV-vis spectra analysis indicates that Ce doping in the compound results in a red-shift of the absorption edge, thus offering increased visible light absorption. We show that such a {gamma}-Fe{sub 2}O{sub 3}-SiO{sub 2}-Ce-doped-TiO{sub 2} core-shell nanocomposite with appreciated Ce doping amount exhibits much higher visible-light photocatalytic activity than bare TiO{sub 2} and undoped {gamma}-Fe{sub 2}O{sub 3}-SiO{sub 2}-TiO{sub 2} core-shell nanocomposite toward the degradation of rhodamine B (RhB). Moreover, the {gamma}-Fe{sub 2}O{sub 3}-SiO{sub 2}-Ce-doped-TiO{sub 2} core-shell nanocomposite photocatalysts could be easily separated and reused from the treated water under application of an external magnetic field. - Graphical abstract: Novel {gamma}-Fe{sub 2}O{sub 3}-SiO{sub 2}-Ce-doped-TiO{sub 2} core/shell nanocomposite photocatalysts with enhanced photocatalytic activity and fast magnetic separability were prepared. Highlights: Black-Right-Pointing-Pointer Novel {gamma}-Fe{sub 2}O{sub 3}-SiO{sub 2}-Ce-doped TiO{sub 2} core/shell composite photocatalysts were prepared. Black-Right-Pointing-Pointer The resulting core/shell composite show high visible light photocatalytic activity. Black-Right-Pointing-Pointer The nanocomposite photocatalysts can be easily recycled with excellent durability.

  3. Stomatal Responses to Light and Leaf-Air Water Vapor Pressure Difference Show Similar Kinetics in Sugarcane and Soybean 1

    PubMed Central

    Grantz, David A.; Zeiger, Eduardo

    1986-01-01

    Stomatal responses to light and humidity (vapor pressure difference, VPD) are important determinants of stomatal conductance. Stomatal movements induced by light are the result of a transduction of the light stimulus into modulated ion fluxes in guard cells and concomitant osmotic adjustments and turgor changes. It is generally assumed that this transduction process is a general stomatal property, with different environmental stimuli integrated into guard cell metabolism through their modulation of ion fluxes. In contrast with this notion, the VPD response, which is unique because both its triggering signal and the turgor changes required for aperture modulations involve water molecules, has been considered to be hydropassive and thus independent of guard cell metabolism. We used a kinetic approach to compare the light and VPD responses in order to test the hypothesis that hydropassive changes in guard cell turgor could be faster than the metabolism-dependent light responses. Changes in stomatal conductance in intact leaves of sugarcane and soybean were measured after application of step changes in VPD and in light. In spite of a 5-fold difference in overall rates between the two species, the response rates following light or VPD steps were similar. Although a coincidental kinetic similarity between two mechanistically different responses cannot be ruled out, the data suggest a common mechanism controlling stomatal movements, with the VPD stimulus inducing metabolic modulations of ion fluxes analogous to other stomatal responses. PMID:16664916

  4. Dependence of Aerosol Light Absorption and Single-Scattering Albedo On Ambient Relative Humidity for Sulfate Aerosols with Black Carbon Cores

    NASA Technical Reports Server (NTRS)

    Redemann, Jens; Russell, Philip B.; Hamill, Patrick

    2001-01-01

    Atmospheric aerosols frequently contain hygroscopic sulfate species and black carbon (soot) inclusions. In this paper we report results of a modeling study to determine the change in aerosol absorption due to increases in ambient relative humidity (RH), for three common sulfate species, assuming that the soot mass fraction is present as a single concentric core within each particle. Because of the lack of detailed knowledge about various input parameters to models describing internally mixed aerosol particle optics, we focus on results that were aimed at determining the maximum effect that particle humidification may have on aerosol light absorption. In the wavelength range from 450 to 750 nm, maximum absorption humidification factors (ratio of wet to 'dry=30% RH' absorption) for single aerosol particles are found to be as large as 1.75 when the RH changes from 30 to 99.5%. Upon lesser humidification from 30 to 80% RH, absorption humidification for single particles is only as much as 1.2, even for the most favorable combination of initial ('dry') soot mass fraction and particle size. Integrated over monomodal lognormal particle size distributions, maximum absorption humidification factors range between 1.07 and 1.15 for humidification from 30 to 80% and between 1.1 and 1.35 for humidification from 30 to 95% RH for all species considered. The largest humidification factors at a wavelength of 450 nm are obtained for 'dry' particle size distributions that peak at a radius of 0.05 microns, while the absorption humidification factors at 700 nm are largest for 'dry' size distributions that are dominated by particles in the radius range of 0.06 to 0.08 microns. Single-scattering albedo estimates at ambient conditions are often based on absorption measurements at low RH (approx. 30%) and the assumption that aerosol absorption does not change upon humidification (i.e., absorption humidification equal to unity). Our modeling study suggests that this assumption alone can

  5. Evaluation of a teflon based ultraviolet light system on the disinfection of water in a textile air washer

    SciTech Connect

    Smith, J.E.; Whisnant, R.B.

    1987-08-01

    The report provides an in-depth evaluation of an ultraviolet (UV) disinfection unit as applied to the treatment of cooling water in a textile air washer system. The UV unit tests used a teflon tube to transport the aquatic phase. The unit reduced microbial populations and maintained an average level of 10,000 Colony formed unites/mL for the 6-month testing period, without the addition of biocides. No cleaning or other maintenance was required of the wetted surfaces during the testing period. Slime deposits observed on walls of the air washer during chemical treatment were also eliminated. The UV unit can be utilized on both cooling towers and air washers without extensive installation.

  6. Calcium ions are involved in the unusual red shift of the light-harvesting 1 Qy transition of the core complex in thermophilic purple sulfur bacterium Thermochromatium tepidum.

    PubMed

    Kimura, Yukihiro; Hirano, Yu; Yu, Long-Jiang; Suzuki, Hiroaki; Kobayashi, Masayuki; Wang, Zheng-Yu

    2008-05-16

    Thermophilic purple sulfur bacterium, Thermochromatium tepidum, can grow at temperatures up to 58 degrees C and exhibits an unusual Qy absorption at 915 nm for the core light-harvesting complex (LH1), an approximately 35-nm red shift from those of its mesophilic counterparts. We demonstrate in this study, using a highly purified LH1-reaction center complex, that the LH1 Qy transition is strongly dependent on metal cations and Ca2+ is involved in the unusual red shift. Removal of the Ca2+ resulted in formation of a species with the LH1 Qy absorption at 880 nm, and addition of the Ca2+ to the 880-nm species recovered the native 915-nm form. Interchange between the two forms is fully reversible. Based on spectroscopic and isothermal titration calorimetry analyses, the Ca2+ binding to the LH1 complex was estimated to occur in a stoichiometric ratio of Ca2+/alphabeta-subunit = 1:1 and the binding constant was in 10(5) m(-1) order of magnitude, which is comparable with those for EF-hand Ca2+-binding proteins. Despite the high affinity, conformational changes in the LH1 complex upon Ca2+ binding were small and occurred slowly, with a typical time constant of approximately 6 min. Replacement of the Ca2+ with other metal cations caused blue shifts of the Qy bands depending on the property of the cations, indicating that the binding site is highly selective. Based on the amino acid sequences of the LH1 complex, possible Ca2+-binding sites are proposed that consist of several acidic amino acid residues near the membrane interfaces of the C-terminal region of the alpha-polypeptide and the N-terminal region of the beta-polypeptide.

  7. Comparison of Standard Light Water Reactor Cross-Section Libraries using the United States Nuclear Regulatory Commission Pressurized Water Reactor Standard Core Loading Benchmark Problem

    NASA Astrophysics Data System (ADS)

    Arzu Alpan, F.; Kulesza, Joel A.

    2016-02-01

    This paper compares contemporary and historical light water reactor shielding and pressure vessel dosimetry cross-section libraries for a pressurized water reactor calculational benchmark problem with a standard out-in core loading. The calculational benchmark problem was developed at Brookhaven National Laboratory by the request of the U. S. Nuclear Regulatory Commission and used the Oak Ridge National Laboratory two-dimensional discrete ordinates code DORT and the BUGLE-93 cross-section library for the calculations. In this paper, a Westinghouse three-dimensional discrete ordinates code with parallel processing, the RAPTOR-M3G code was used. A variety of cross section libraries were used with RAPTOR-M3G including the BUGLE-93, BUGLE-96, and BUGLE-B7 cross-section libraries developed at Oak Ridge National Laboratory, and the broad-group ALPAN-VII.0 cross-section library developed at Westinghouse. In comparing the calculation-to-calculation reaction rates using the BUGLE-93 cross-section library at the thermal shield, pressure vessel, and cavity capsules, for eleven dosimetry reaction rates, a maximum relative difference of 5% was observed, with the exception of 65Cu(n,2n) in the pressure vessel capsule that had a 90% relative difference with respect to the reference results. It is thought that the 65Cu(n,2n) reaction rate reported in the reference for the pressure vessel capsule is not correct. In considering the libraries developed after BUGLE-93, a maximum relative difference of 12% was observed in reaction rates, with respect to the reference results, for 237Np(n,f) in the cavity capsule using BUGLE-B7.

  8. Biomolecular Markers within the Core Axis of Aging and Particulate Air Pollution Exposure in the Elderly: A Cross-Sectional Study

    PubMed Central

    Pieters, Nicky; Janssen, Bram G.; Dewitte, Harrie; Cox, Bianca; Cuypers, Ann; Lefebvre, Wouter; Smeets, Karen; Vanpoucke, Charlotte; Plusquin, Michelle; Nawrot, Tim S.

    2015-01-01

    .5. Citation: Pieters N, Janssen BG, Dewitte H, Cox B, Cuypers A, Lefebvre W, Smeets K, Vanpoucke C, Plusquin M, Nawrot TS. 2016. Biomolecular markers within the core axis of aging and particulate air pollution exposure in the elderly: a cross-sectional study. Environ Health Perspect 124:943–950; http://dx.doi.org/10.1289/ehp.1509728 PMID:26672058

  9. Fabrication and different photoelectric responses of nanocrystalline ZnO film irradiated with UV and white light in dry air

    NASA Astrophysics Data System (ADS)

    Zou, Zhijun; Qiu, Yang; Xie, Changsheng; Xu, Jingjing; Luo, Yongsong; Wang, Chunlei; Yan, Hailong

    2015-09-01

    In this paper, nanocrystalline ZnO film with porous structure was successfully prepared on alumina substrate by the technology of screen printing and the subsequent heat treatment. The fundamental characteristics of the as-prepared sample were examined through XRD, FE-SEM, EDX and PL spectra measurements. Meanwhile, photoelectric responses of it were tested under UV and white light irradiation, respectively. Different photocurrent curves were obtained. Under UV light, the photocurrent with comparatively high amplitude of each cycle could mostly recover upon the light off. While for white light, the photocurrent with low amplitude just partially recovered when the light was turned off. This phenomenon indicated that, after the white light off, a large number of free electrons still remained within the materials. To calculate the amount of the remained free electrons, three photocurrent parameters, which are related to the density of free electrons in ZnO, were defined for the first time. Furthermore, the explanations for the different photoelectric responses of ZnO based on the double Schottky barrier model were also proposed.

  10. Light extinction by fine atmospheric particles in the White Mountains region of New Hampshire and its relationship to air mass transport.

    PubMed

    Slater, John F; Dibb, Jack E; Keim, Barry D; Talbot, Robert W

    2002-03-27

    Chemical, optical, and physical measurements of fine aerosols (aerodynamic diameter < or = 2.5 microm) have been performed at a mountaintop location adjacent to the White Mountain National Forest in northern NH, USA. A 1-month long sampling campaign was conducted at Cranmore Mountain during spring 2000. We report on the apportionment of light extinction by fine aerosols into its major chemical components, and relationships between variations in aerosol parameters and changes in air mass origin. Filter-based, 24-h integrated samples were collected and analyzed for major inorganic ions, as well as organic (OC), elemental (EC), and total carbon. Light scattering and light absorption coefficients were measured at 5-min intervals using an integrating nephelometer and a light absorption photometer. Fine particle number density was measured with a condensation particle counter. Air mass origins and transport patterns were investigated through the use of 3-day backward trajectories and a synoptic climate classification system. Two distinct transport regimes were observed: (1) flow from the north/northeast (N/NE) occurred during 9 out of 18 sample-days; and (2) flow from the west/southwest (W/SW) occurred 8 out of 18 sample-days. All measured and derived aerosol and meteorological parameters were separated into two categories based on these different flow scenarios. During W/SW flow, higher values of aerosol chemical concentration, absorption and scattering coefficients, number density, and haziness were observed compared to N/NE flow. The highest level of haziness was associated with the climate classification Frontal Atlantic Return, which brought polluted air into the region from the mid-Atlantic corridor. Fine particle mass scattering efficiencies of (NH4)2SO4 and OC were 5.35 +/- 0.42 m2 g(-1) and 1.56 +/- 0.40 m2 g(-1), respectively, when transport was out of the N/NE. When transport was from the W/SW the values were 4.94 +/- 0.68 m2 g(-1) for (NH4)2SO4 and 2.18 +/- 0

  11. Real-Time Spectroscopic Monitoring of the Synthesis of Core and Core/Shell Upconversion Nanocrystals and Finite-Difference Time Domain Modeling of the Interaction Between Light and Spherical Microwell Arrays

    NASA Astrophysics Data System (ADS)

    Suter, John

    Nanocrystalline beta-NaYF4:17% Yb3+, 3% Er 3+ has significant potential for applications in a wide variety of fields including solar technologies, security printing, and biological imaging and sensing. In order to increase the potential of these nanocrystals for these applications, we have developed a method for the real-time, in situ, spectroscopic monitoring of nanocrystal growth and shell-addition. In situ real-time monitoring of upconversion emission is applied to study the reaction mechanism for the synthesis of beta-NaYF 4:17% Yb3+, 3% Er3++ nanoparticles in oleic acid and octadecene via the heat-up method. Transmission electron microscopy is used to correlate the spectroscopic signature of the reaction mixture with its composition. The power of real-time spectroscopic monitoring to precisely time the duration of the various stages of the reaction, and to accurately identify the transitions between those stages, including the completion of the reaction, is demonstrated. Real-time spectroscopic monitoring is used to study the effect of increasing the oleic acid concentration on the duration of these stages as well as the size and shape of resulting nanocrystals. The use of real-time spectroscopic monitoring to study shell-addition, specifically, the addition of an un-doped NaYF4 shell, is also discussed. Patterned gold surfaces are known to enhance the upconversion efficiency of lanthanide based upconversion materials, such as nanocrystalline beta-NaYF 4:17% Yb3+, 3% Er3+. Here, spherical microwell arrays are shown to provide up to a 40x enhancement of upconversion emission from beta-NaYF4:17% Yb3+, 3% Er 3+ nanocrystals. Finite-Difference Time-Domain (FDTD) is a method to solve, numerically, the Maxwell equations across a 3D simulation grid and has been used to simulate the interaction of light with a variety of materials, including metal surfaces and particles. FDTD simulations is used to investigate the nature of the enhancement from the patterned gold

  12. Mercury's core evolution

    NASA Astrophysics Data System (ADS)

    Deproost, Marie-Hélène; Rivoldini, Attilio; Van Hoolst, Tim

    2016-10-01

    Remote sensing data of Mercury's surface by MESSENGER indicate that Mercury formed under reducing conditions. As a consequence, silicon is likely the main light element in the core together with a possible small fraction of sulfur. Compared to sulfur, which does almost not partition into solid iron at Mercury's core conditions and strongly decreases the melting temperature, silicon partitions almost equally well between solid and liquid iron and is not very effective at reducing the melting temperature of iron. Silicon as the major light element constituent instead of sulfur therefore implies a significantly higher core liquidus temperature and a decrease in the vigor of compositional convection generated by the release of light elements upon inner core formation.Due to the immiscibility in liquid Fe-Si-S at low pressure (below 15 GPa), the core might also not be homogeneous and consist of an inner S-poor Fe-Si core below a thinner Si-poor Fe-S layer. Here, we study the consequences of a silicon-rich core and the effect of the blanketing Fe-S layer on the thermal evolution of Mercury's core and on the generation of a magnetic field.

  13. Air-Stable, Cross-Linkable, Hole-Injecting/Transporting Interlayers for Improved Charge Injection in Organic Light-Emitting Diodes

    SciTech Connect

    Li,J.; Marks, T.

    2008-01-01

    Modification of inorganic electrode surfaces has attracted great attention in the quest to optimize organic optoelectronic devices. An air-stable, cross-linkable trimethoxysilane functionalized hole-transporting triarylamine (4,4'-bis[(p-trimethoxysilylpropylphenyl)phenylamino]biphenyl, TPD-[Si(OMe)3]2) has been synthesized and self-assembled or spin-coated onto tin-doped indium oxide (ITO) anode surfaces to form monolayers or multilayer siloxane films, respectively. The modified ITO surfaces were characterized by advancing aqueous contact angle, X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and cyclic voltammetry (CV). Increased surface work function and enhanced ITO-hole transport layer (HTL) contact via robust covalent bonding are expected to facilitate hole injection from the ITO anode, resulting in organic light-emitting diode (OLED) performance enhancement versus that of a device without such interlayers. For a device having the structure ITO/spin-coated-TPD-[Si(OMe)3]2 from aqueous alcohol + acetic acid blend solution (40 nm)/NPB (20 nm)/Alq (60 nm)/LiF (1 nm)/Al (100 nm), a maximum light output of 32800 cd/m2, a 4.25 V turn-on voltage, and a maximum current efficiency of 5.8 cd/A is achieved. This performance is comparable to or superior to that of analogous devices prepared with analogous trichorosilyl precursors. The air-stable interlayer material developed here is also applicable to large-area coating techniques.

  14. Visible-Light-Promoted and Yb(OTf)3-Catalyzed Constructions of Coumarin-Pyrrole-(Iso)quinoline-Fused Pentacycles: Synthesis of Lamellarin Core, Lamellarin D Trimethyl Ether, and Lamellarin H.

    PubMed

    Manjappa, Kiran B; Syu, Jia-Ru; Yang, Ding-Yah

    2016-01-15

    The efficient construction of a coumarin-pyrrole-isoquinoline-fused pentacycle via the visible-light-promoted cyclization of 4-(isoquinolin-1-ylmethyl)-3-nitrocoumarin or Yb(OTf)3-catalyzed coupling of 4-chloro-3-nitrocoumarin and 1-methylisoquinoline is reported. This methodology has further led to the development of the concise synthesis of the lamellarin core in one, two, and three steps, as well as of lamellarin D trimethyl ether in three steps. PMID:26741300

  15. Reflection and transmission of light waves from the air-magnetoplasma interface: Spatial and angular Imbert-Fedorov shifts

    SciTech Connect

    Borhanian, Jafar

    2015-03-15

    We have investigated the reflection and transmission of an electromagnetic wave from the air-magnetoplasma interface. The reflection and transmission coefficients are obtained for an arbitrary polarized incident wave. The spatial and angular Imbert-Fedorov (IF) shifts are discussed. The numerical results are presented to study the dependence of the reflection and transmission coefficients and IF shifts on relevant parameters of the system. The plasma and wave parameters can be used to control the reflection coefficients and IF shifts.

  16. The nuclear starburst in Arp 299-A: from the 5.0 GHz VLBI radio light-curves to its core-collapse supernova rate

    NASA Astrophysics Data System (ADS)

    Bondi, M.; Pérez-Torres, M. A.; Herrero-Illana, R.; Alberdi, A.

    2012-03-01

    Context. The nuclear region of the luminous infrared galaxy (LIRG) Arp 299-A hosts a recent ( ≃ 10 Myr) intense burst of massive star formation that is expected to lead to numerous core-collapse supernovae (CCSNe). Previous VLBI observations, carried out with the European VLBI Network (EVN) at 5.0 GHz and with the VLBA at 2.3 and 8.4 GHz, resulted in the detection of many compact, bright, non-thermal sources in a region ≲ 150 pc in size. Aims: We aim to establish the nature of all non-thermal compact components in Arp 299-A, as well as to estimate its core-collapse supernova rate. While the majority of the compact components are expected to be young radio supernovae (RSNe) and supernova remnants (SNRs), a definitive classification is still lacking. Yet, this is very relevant for eventually establishing the CCSN rate, as well as the star formation rate, for this galaxy. Methods: We used multi-epoch EVN observations taken at 5.0 GHz to image the compact radio sources in the nuclear region of Arp 299-A with milliarcsecond resolution. We also used one single-epoch 5.0 GHz Multi-Element Radio Linked Interferometer Network (MERLIN) observation to image the extended emission in which these compact radio sources are embedded. Results: We present the first 5.0 GHz radio light-curve (spanning ~2.5 yr) of all compact components in the nuclear starburst of Arp 299-A. Twenty-six compact sources are detected, eight of which are new objects. The properties of all detected objects are consistent with them being a mixed population of CCSNe and SNRs. We find clear evidence for at least two new CCSNe, implying a lower limit to the CCSN rate of νSN ≳ 0.80 SN/yr, indicating that the bulk of the current star formation in Arp 299-A is taking place in the innermost ~150 pc.A few more objects show variability consistent with them being recently exploded SNe, but only future observations will clarify this point. Our MERLIN observations trace a region of diffuse extended emission that

  17. Monte Carlo simulation of a quantum noise limited Čerenkov detector based on air-spaced light guiding taper for megavoltage x-ray imaging

    SciTech Connect

    Teymurazyan, A.; Rowlands, J. A.; Pang, G.

    2014-04-15

    Purpose: Electronic Portal Imaging Devices (EPIDs) have been widely used in radiation therapy and are still needed on linear accelerators (Linacs) equipped with kilovoltage cone beam CT (kV-CBCT) or MRI systems. Our aim is to develop a new high quantum efficiency (QE) Čerenkov Portal Imaging Device (CPID) that is quantum noise limited at dose levels corresponding to a single Linac pulse. Methods: Recently a new concept of CPID for MV x-ray imaging in radiation therapy was introduced. It relies on Čerenkov effect for x-ray detection. The proposed design consisted of a matrix of optical fibers aligned with the incident x-rays and coupled to an active matrix flat panel imager (AMFPI) for image readout. A weakness of such design is that too few Čerenkov light photons reach the AMFPI for each incident x-ray and an AMFPI with an avalanche gain is required in order to overcome the readout noise for portal imaging application. In this work the authors propose to replace the optical fibers in the CPID with light guides without a cladding layer that are suspended in air. The air between the light guides takes on the role of the cladding layer found in a regular optical fiber. Since air has a significantly lower refractive index (∼1 versus 1.38 in a typical cladding layer), a much superior light collection efficiency is achieved. Results: A Monte Carlo simulation of the new design has been conducted to investigate its feasibility. Detector quantities such as quantum efficiency (QE), spatial resolution (MTF), and frequency dependent detective quantum efficiency (DQE) have been evaluated. The detector signal and the quantum noise have been compared to the readout noise. Conclusions: Our studies show that the modified new CPID has a QE and DQE more than an order of magnitude greater than that of current clinical systems and yet a spatial resolution similar to that of current low-QE flat-panel based EPIDs. Furthermore it was demonstrated that the new CPID does not require an

  18. Efficiently Enhancing Visible Light Photocatalytic Activity of Faceted TiO2 Nanocrystals by Synergistic Effects of Core-Shell Structured Au@CdS Nanoparticles and Their Selective Deposition.

    PubMed

    Tong, Ruifeng; Liu, Chang; Xu, Zhenkai; Kuang, Qin; Xie, Zhaoxiong; Zheng, Lansun

    2016-08-24

    Integrating wide bandgap semiconductor photocatalysts with visible-light-active inorganic nanoparticles (such as Au and CdS) as sensitizers is one of the most efficient methods to improve their photocatalytic activity in the visible light region. However, as for all such composite photocatalysts, a rational design and precise control over their architecture is often required to achieve optimal performance. Herein, a new TiO2-based ternary composite photocatalyst with superior visible light activity was designed and synthesized. In this composite photocatalyst, the location of the visible light sensitizers was engineered according to the intrinsic facet-induced effect of well-faceted TiO2 nanocrystals on the spatial separation of photogenerated carriers. Experimentally, core-shell structured Au@CdS nanoparticles acting as visible light sensitizers were selectively deposited onto photoreductive {101} facets of well-faceted anatase TiO2 nanocrystals through a two-step in situ photodeposition route. Because the combination of Au@CdS and specific {101} facets of TiO2 nanocrystals facilitates the transport of charges photogenerated under visible light irradiation, this well-designed ternary composite photocatalyst exhibited superior activity in visible-light-driven photocatalytic H2 evolution, as expected. PMID:27479634

  19. Low-temperature ignition delay for hydrogen-air mixtures in light of a reaction mechanism with quantum correction

    NASA Astrophysics Data System (ADS)

    Medvedev, S. P.; Agafonov, G. L.; Khomik, S. V.

    2016-09-01

    A reaction mechanism with quantum correction is used to model low-temperature/high-pressure autoignition of lean hydrogen-air mixtures. This approach provides a good approximation for experimental data on autoignition delay and the low activation energy observed in experiments. Calculated results demonstrate that ignition delay time is inversely proportional to pressure, squared. The proposed scaling reduces spread in experimental data. The application of a quantum correction to hydrogen oxidation provides a basis for developing a general reaction mechanism that can be used to predict the autoignition behavior of hydrogen over an entire temperature/pressure range relevant to rocket engine conditions.

  20. Technical report series on global modeling and data assimilation. Volume 5: Documentation of the AIRES/GEOS dynamical core, version 2

    NASA Technical Reports Server (NTRS)

    Suarez, Max J. (Editor); Takacs, Lawrence L.

    1995-01-01

    A detailed description of the numerical formulation of Version 2 of the ARIES/GEOS 'dynamical core' is presented. This code is a nearly 'plug-compatible' dynamics for use in atmospheric general circulation models (GCMs). It is a finite difference model on a staggered latitude-longitude C-grid. It uses second-order differences for all terms except the advection of vorticity by the rotation part of the flow, which is done at fourth-order accuracy. This dynamical core is currently being used in the climate (ARIES) and data assimilation (GEOS) GCMs at Goddard.

  1. High Light Absorption and Charge Separation Efficiency at Low Applied Voltage from Sb-Doped SnO2/BiVO4 Core/Shell Nanorod-Array Photoanodes.

    PubMed

    Zhou, Lite; Zhao, Chenqi; Giri, Binod; Allen, Patrick; Xu, Xiaowei; Joshi, Hrushikesh; Fan, Yangyang; Titova, Lyubov V; Rao, Pratap M

    2016-06-01

    BiVO4 has become the top-performing semiconductor among photoanodes for photoelectrochemical water oxidation. However, BiVO4 photoanodes are still limited to a fraction of the theoretically possible photocurrent at low applied voltages because of modest charge transport properties and a trade-off between light absorption and charge separation efficiencies. Here, we investigate photoanodes composed of thin layers of BiVO4 coated onto Sb-doped SnO2 (Sb:SnO2) nanorod-arrays (Sb:SnO2/BiVO4 NRAs) and demonstrate a high value for the product of light absorption and charge separation efficiencies (ηabs × ηsep) of ∼51% at an applied voltage of 0.6 V versus the reversible hydrogen electrode, as determined by integration of the quantum efficiency over the standard AM 1.5G spectrum. To the best of our knowledge, this is one of the highest ηabs × ηsep efficiencies achieved to date at this voltage for nanowire-core/BiVO4-shell photoanodes. Moreover, although WO3 has recently been extensively studied as a core nanowire material for core/shell BiVO4 photoanodes, the Sb:SnO2/BiVO4 NRAs generate larger photocurrents, especially at low applied voltages. In addition, we present control experiments on planar Sb:SnO2/BiVO4 and WO3/BiVO4 heterojunctions, which indicate that Sb:SnO2 is more favorable as a core material. These results indicate that integration of Sb:SnO2 nanorod cores with other successful strategies such as doping and coating with oxygen evolution catalysts can move the performance of BiVO4 and related semiconductors closer to their theoretical potential.

  2. Composite Cores

    NASA Technical Reports Server (NTRS)

    1990-01-01

    Spang & Company's new configuration of converter transformer cores is a composite of gapped and ungapped cores assembled together in concentric relationship. The net effect of the composite design is to combine the protection from saturation offered by the gapped core with the lower magnetizing requirement of the ungapped core. The uncut core functions under normal operating conditions and the cut core takes over during abnormal operation to prevent power surges and their potentially destructive effect on transistors. Principal customers are aerospace and defense manufacturers. Cores also have applicability in commercial products where precise power regulation is required, as in the power supplies for large mainframe computers.

  3. Membrane-Based Air Composition Control for Light-Duty Diesel Vehicles: A Benefit and Cost Assessment

    SciTech Connect

    K. Stork; R. Poola

    1998-10-01

    This report presents the methodologies and results of a study conducted by Argonne National Laboratory (Argonne) to assess the benefits and costs of several membrane-based technologies. The technologies evaluated will be used in automotive emissions-control and performance-enhancement systems incorporated into light-duty diesel vehicle engines. Such engines are among the technologies that are being considered to power vehicles developed under the government-industry Partnership for a New Generation of Vehicles (PNGV). Emissions of nitrogen oxides (NO{sub x}) from diesel engines have long been considered a barrier to use of diesels in urban areas. Recently, particulate matter (PM) emissions have also become an area of increased concern because of new regulations regarding emissions of particulate matter measuring 2.5 micrometers or less (PM{sub 2.5}). Particulates are of special concern for diesel engines in the PNGV program; the program has a research goal of 0.01 gram per mile (g/mi) of particulate matter emissions under the Federal Test Procedure (FTP) cycle. This extremely low level (one-fourth the level of the Tier II standard) could threaten the viability of using diesel engines as stand-alone powerplants or in hybrid-electric vehicles. The techniques analyzed in this study can reduce NO{sub x} and particulate emissions and even increase the power density of the diesel engines used in light-duty diesel vehicles.

  4. Transition from downward to upward air-sea momentum transfer in swell-dominated light wind condition

    NASA Astrophysics Data System (ADS)

    Smedman, Ann-Sofi; Högström, Ulf; Rutgersson, Anna

    2016-04-01

    Atmospheric and surface wave data from two oceanic experiments carried out on FLIP and ASIS platforms are analysed in order to identify swell-related effects on the momentum exchange during low wind speed conditions. The RED experiment was carried out on board an R/P Floating Instrument Platform, FLIP, anchored north east of the Hawaiian island Oahu with sonic anemometers at four levels: 5.1 m, 6.9 m, 9.9 m and 13.8 m respectively. The meteorological conditions were characterized by north- easterly trade wind and with swell present during most of the time. During swell the momentum flux was directed downwards meaning a positive contribution to the stress. The FETCH experiment was carried out in the Gulf of Lion in the north-western Mediterranean Sea. On the ASIS (air-sea interaction spar) buoy a sonic anemometer was mounted at 7 m above the mean surface level. During strong swell conditions the momentum flux was directed upwards meaning a negative contribution to the stress in this case. The downward momentum flux is shown to be a function of the orbital circulation while the upward momentum flux is a function of wave height. The dividing wind speed is found to be 3.5 m/s Conclusion: Wind speed > 3.5 m/s creates waves (ripples) and thus roughness. Combination of orbital motion and asymmetric structure of ripples lead to flow perturbation and downward transport of negative momentum. With low wind speed (no ripples but viscosity) circulations will form above the crest and the trough with opposite direction which will cause a pressure drop in the vertical direction and an upward momentum transport from the water to the air.

  5. Facile synthesis of gold nanorods/hydrogels core/shell nanospheres for pH and near-infrared-light induced release of 5-fluorouracil and chemo-photothermal therapy.

    PubMed

    Jin, Hui; Liu, Xifeng; Gui, Rijun; Wang, Zonghua

    2015-04-01

    We described a facile synthesis of pH and near-infrared (NIR) light dual-sensitive core/shell hybrid nanospheres, consisting of gold nanorods (GNR) as the core and poly(N-isopropylacrylamide-co-methacrylic acid) as the shell, p(NIPAM-MAA). The resultant GNR/p(NIPAM-MAA) nanospheres showed a core/shell structure, with an average diameter of ∼110nm and a strong longitudinal surface plasmon band at NIR region. Due to the photothermal effect of GNR and pH/thermal-sensitive volume transition of p(NIPAM-MAA) hydrogels, the nanospheres with loading of 5-fluorouracil (5-FU) by electrostatic interactions were developed as a smart carrier for pH- and photothermal-induced release of 5-FU. Experimental results testified that the cumulative release of 5-FU from nanospheres was markedly increased in a mild acidic medium. Moreover, a NIR light (808nm) irradiation triggered a greater and faster release of 5-FU, which was further testified by relevant results from in vitro cytotoxicity assay, in vivo tumor growth inhibition and histological images of ex vivo tumor sections. These results revealed significant applications of GNR/p(NIPAM-MAA) nanospheres in controlled release of anticancer agents and photothermal ablation therapy of tumor tissues, accompanied by synergistic effect of chem-photothermal therapy.

  6. Facile synthesis of gold nanorods/hydrogels core/shell nanospheres for pH and near-infrared-light induced release of 5-fluorouracil and chemo-photothermal therapy.

    PubMed

    Jin, Hui; Liu, Xifeng; Gui, Rijun; Wang, Zonghua

    2015-04-01

    We described a facile synthesis of pH and near-infrared (NIR) light dual-sensitive core/shell hybrid nanospheres, consisting of gold nanorods (GNR) as the core and poly(N-isopropylacrylamide-co-methacrylic acid) as the shell, p(NIPAM-MAA). The resultant GNR/p(NIPAM-MAA) nanospheres showed a core/shell structure, with an average diameter of ∼110nm and a strong longitudinal surface plasmon band at NIR region. Due to the photothermal effect of GNR and pH/thermal-sensitive volume transition of p(NIPAM-MAA) hydrogels, the nanospheres with loading of 5-fluorouracil (5-FU) by electrostatic interactions were developed as a smart carrier for pH- and photothermal-induced release of 5-FU. Experimental results testified that the cumulative release of 5-FU from nanospheres was markedly increased in a mild acidic medium. Moreover, a NIR light (808nm) irradiation triggered a greater and faster release of 5-FU, which was further testified by relevant results from in vitro cytotoxicity assay, in vivo tumor growth inhibition and histological images of ex vivo tumor sections. These results revealed significant applications of GNR/p(NIPAM-MAA) nanospheres in controlled release of anticancer agents and photothermal ablation therapy of tumor tissues, accompanied by synergistic effect of chem-photothermal therapy. PMID:25794443

  7. Cartilage Tissue Engineering Application of Injectable Gelatin Hydrogel with In Situ Visible-Light-Activated Gelation Capability in Both Air and Aqueous Solution

    PubMed Central

    Lin, Hang; Cheng, Anthony Wai-Ming; Alexander, Peter G.; Beck, Angela M.

    2014-01-01

    Chondroprogenitor cells encapsulated in a chondrogenically supportive, three-dimensional hydrogel scaffold represents a promising, regenerative approach to articular cartilage repair. In this study, we have developed an injectable, biodegradable methacrylated gelatin (mGL)–based hydrogel capable of rapid gelation via visible light (VL)–activated crosslinking in air or aqueous solution. The mild photocrosslinking conditions permitted the incorporation of cells during the gelation process. Encapsulated human-bone-marrow-derived mesenchymal stem cells (hBMSCs) showed high, long-term viability (up to 90 days) throughout the scaffold. To assess the applicability of the mGL hydrogel for cartilage tissue engineering, we have evaluated the efficacy of chondrogenesis of the encapsulated hBMSCs, using hBMSCs seeded in agarose as control. The ability of hBMSC-laden mGL constructs to integrate with host tissues after implantation was further investigated utilizing an in vitro cartilage repair model. The results showed that the mGL hydrogel, which could be photopolymerized in air and aqueous solution, supports hBMSC growth and TGF-β3-induced chondrogenesis. Compared with agarose, mGL constructs laden with hBMSCs are mechanically stronger with time, and integrate well with native cartilage tissue upon implantation based on push-out mechanical testing. VL-photocrosslinked mGL scaffold thus represents a promising scaffold for cell-based repair and resurfacing of articular cartilage defects. PMID:24575844

  8. Active layer-incorporated, spectrally tuned Au/SiO2 core/shell nanorod-based light trapping for organic photovoltaics.

    PubMed

    Janković, Vladan; Yang, Yang Michael; You, Jingbi; Dou, Letian; Liu, Yongsheng; Cheung, Puilam; Chang, Jane P; Yang, Yang

    2013-05-28

    We demonstrate that incorporation of octadecyltrimethoxysilane (OTMS)-functionalized, spectrally tuned, gold/silica (Au/SiO2) core/shell nanospheres and nanorods into the active layer of an organic photovoltaic (OPV) device led to an increase in photoconversion efficiency (PCE). A silica shell layer was added onto Au core nanospheres and nanorods in order to provide an electrically insulating surface that does not interfere with carrier generation and transport inside the active layer. Functionalization of the Au/SiO2 core/shell nanoparticles with the OTMS organic ligand was then necessary to transfer the Au/SiO2 core/shell nanoparticles from an ethanol solution into an OPV polymer-compatible solvent, such as dichlorobenzene. The OTMS-functionalized Au/SiO2 core/shell nanorods and nanospheres were then incorporated into the active layers of two OPV polymer systems: a poly(3-hexylthiophene):[6,6]-phenyl-C61-butyric acid methyl ester (P3HT:PCB60M) OPV device and a poly[2,6-4,8-di(5-ethylhexylthienyl)benzo[1,2-b;3,4-b]dithiophene-alt-5-dibutyloctyl-3,6-bis(5-bromothiophen-2-yl)pyrrolo[3,4-c]pyrrole-1,4-dione] (PBDTT-DPP:PC60BM) OPV device. For the P3HT:PC60BM polymer with a band edge of ~700 nm, the addition of the core/shell nanorods with an aspect ratio (AR) of ~2.5 (extinction peak ~670 nm) resulted in a 7.1% improvement in PCE, while for the PBDTT-DPP:PC60BM polymer with a band edge of ~860 nm, the addition of core/shell nanorods with an AR of ~4 (extinction peak ~830 nm) resulted in a 14.4% improvement in PCE. The addition of Au/SiO2 core/shell nanospheres to the P3HT:PC60BM polymer resulted in a 2.7% improvement in PCE, while their addition to a PBDTT-DPP:PC60BM polymer resulted in a 9.1% improvement. The PCE and Jsc enhancements were consistent with external quantum efficiency (EQE) measurements, and the EQE enhancements spectrally matched the extinction spectra of Au/SiO2 nanospheres and nanorods in both OPV polymer systems.

  9. Environmental Technology Verification: Supplement to Test/QA Plan for Biological and Aerosol Testing of General Ventilation Air Cleaners; Bioaerosol Inactivation Efficiency by HVAC In-Duct Ultraviolet Light Air Cleaners

    EPA Science Inventory

    The Air Pollution Control Technology Verification Center has selected general ventilation air cleaners as a technology area. The Generic Verification Protocol for Biological and Aerosol Testing of General Ventilation Air Cleaners is on the Environmental Technology Verification we...

  10. Nanocrystalline Si/SiO{sub 2} core-shell network with intense white light emission fabricated by hot-wire chemical vapor deposition

    SciTech Connect

    Matsumoto, Y. Dutt, A.; Santana-Rodríguez, G.; Santoyo-Salazar, J.; Aceves-Mijares, M.

    2015-04-27

    We report the fabrication of a stable Si/SiO{sub 2} core-shell network using hot-wire chemical vapor deposition on a silicon substrate at a relatively low substrate temperature of 200 °C. Structural investigations using transmission electron microscopy and X-ray diffraction confirm the presence of nanocrystalline silicon and silicon dioxide quantum dots in the form of a core-shell network embedded in the amorphous SiO{sub x} matrix, while selected area electron diffraction confirms the formation of a core-shell structure. The core-shell structure exhibits a bright white emission that can be seen with the unaided eye at room temperature without any post-annealing treatments, and the observed photoemission does not alter in color or intensity after prolonged laser exposure. Additional measurements are performed while varying the laser power and optical gain is found in the as-deposited material. Intense stable white luminescence is observed and shows the prospective for various optical and biological applications in the future.

  11. Growth of metal-semiconductor core-multishell nanorods with optimized field confinement and nonlinear enhancement

    NASA Astrophysics Data System (ADS)

    Nan, Fan; Xie, Fang-Ming; Liang, Shan; Ma, Liang; Yang, Da-Jie; Liu, Xiao-Li; Wang, Jia-Hong; Cheng, Zi-Qiang; Yu, Xue-Feng; Zhou, Li; Wang, Qu-Quan; Zeng, Jie

    2016-06-01

    This paper describes a facile method for the synthesis of Au/AuAg/Ag2S/PbS core-multishell nanorods with double trapping layers. The synthesis, in sequence, involved deposition of Ag shells onto the surfaces of Au nanorod seeds, formation of AuAg shells by a galvanic replacement reaction, and overgrowth of the Ag2S shells and PbS shells. The resulting core-multishell nanorod possesses an air gap between the Au core and the AuAg shell. Together with the Ag2S shell, the air gap can efficiently trap light, causing strong field confinement and nonlinear enhancement. The as-prepared Au/AuAg/Ag2S/PbS core-multishell nanorods display distinct localized surface plasmon resonance and nonlinear optical properties, demonstrating an effective pathway for maneuvering the optical properties of nanocavities.This paper describes a facile method for the synthesis of Au/AuAg/Ag2S/PbS core-multishell nanorods with double trapping layers. The synthesis, in sequence, involved deposition of Ag shells onto the surfaces of Au nanorod seeds, formation of AuAg shells by a galvanic replacement reaction, and overgrowth of the Ag2S shells and PbS shells. The resulting core-multishell nanorod possesses an air gap between the Au core and the AuAg shell. Together with the Ag2S shell, the air gap can efficiently trap light, causing strong field confinement and nonlinear enhancement. The as-prepared Au/AuAg/Ag2S/PbS core-multishell nanorods display distinct localized surface plasmon resonance and nonlinear optical properties, demonstrating an effective pathway for maneuvering the optical properties of nanocavities. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr09151a

  12. Voltage-induced electroluminescence characteristics of hybrid light-emitting diodes with CdSe/Cd/ZnS core-shell nanoparticles embedded in a conducting polymer on plastic substrates

    NASA Astrophysics Data System (ADS)

    Kwak, Kiyeol; Cho, Kyoungah; Kim, Sangsig

    2014-03-01

    We investigate the electroluminescence (EL) characteristics of a hybrid light-emitting diode (HyLED) with an emissive layer comprised of CdSe/Cd/ZnS core-shell nanoparticles (NPs) embedded in poly(9,9-di-n-octylfluorenyl-2,7-diyl) (PFO) on a plastic substrate. The EL characteristics change dramatically with increasing of the biased voltage. At low voltages, recombination of electrons and holes occurs only in the PFO film because of poor charge transfer in the PFO-CdSe/Cd/ZnS NPs composite film, while the color of the light-emitting from the HyLED changes from blue to red as the biased voltage increases from 7.5 to 17.5 V. We examine and discuss the mechanism of this color tunability.

  13. Voltage-induced electroluminescence characteristics of hybrid light-emitting diodes with CdSe/Cd/ZnS core-shell nanoparticles embedded in a conducting polymer on plastic substrates

    SciTech Connect

    Kwak, Kiyeol; Cho, Kyoungah E-mail: sangsig@korea.ac.kr; Kim, Sangsig E-mail: sangsig@korea.ac.kr

    2014-03-10

    We investigate the electroluminescence (EL) characteristics of a hybrid light-emitting diode (HyLED) with an emissive layer comprised of CdSe/Cd/ZnS core-shell nanoparticles (NPs) embedded in poly(9,9-di-n-octylfluorenyl-2,7-diyl) (PFO) on a plastic substrate. The EL characteristics change dramatically with increasing of the biased voltage. At low voltages, recombination of electrons and holes occurs only in the PFO film because of poor charge transfer in the PFO-CdSe/Cd/ZnS NPs composite film, while the color of the light-emitting from the HyLED changes from blue to red as the biased voltage increases from 7.5 to 17.5 V. We examine and discuss the mechanism of this color tunability.

  14. Particle distributions in approximately 10(13) - 10(16) eV air shower cores at mountain altitude and comparison with Monte Carlo simulations

    NASA Technical Reports Server (NTRS)

    Ash, A. G.

    1985-01-01

    Photographs of 521 shower cores in an array of current-limited spark (discharge) chambers at Sacramento Peak (2900m above sea level, 730 g /sq cm.), New Mexico, U.S.A., have been analyzed and the results compared with similar data from Leeds (80m above sea level, 1020 g sq cm.). It was found that the central density differential spectrum is consistent with a power law index of -2 up to approx. 1500/sq m where it steepens, and that shower cores become flatter on average with increasing size. Scaling model predictions for proton primaries with a approx E sup -2.71 energy spectrum account well for the altitude dependence of the data at lower densities. However, deviations at higher densities indicate a change in hadron interaction characteristics between approx few x 10 to the 14th power and 10 to the 15th power eV primary energy causing particles close to the shower axis to be spread further out.

  15. Core-shell Cd0.2Zn0.8S@BiOX (X = Cl, Br and I) microspheres: a family of hetero-structured catalysts with adjustable bandgaps, enhanced stability and photocatalytic performance under visible light irradiation.

    PubMed

    Zhou, Yannan; Wen, Ting; Chang, Binbin; Yang, Baocheng; Wang, Yonggang

    2016-09-21

    Heterostructures consisting of two semiconductors have merited considerable attention in photocatalytic applications due to synergistic effects in complex redox processes. The incorporation of solid solutions into such architectures can further offer extra variability to control the bandgap. In this study, we report the fabrication of a series of core-shell Cd0.2Zn0.8S@BiOX (X = Cl, Br and I) microspheres via a solvothermal route that lead to enhanced photocatalytic performance under visible light irradiation. By optimizing the synthesis conditions, uniform and porous Cd0.2Zn0.8S@BiOX microspheres were achieved. The products were thoroughly characterized by X-ray diffraction studies, scanning electron microscopy, transmission electron microscopy, photoluminescence studies, absorption measurements and the photodegradation of RhB. Remarkably, the electronic structures of Cd0.2Zn0.8S@BiOX composites can be continuously tuned by varying the composition of BiOX to achieve the best catalytic performance under visible light irradiation. Finally, this greatly enhanced visible-light-driven photocatalytic efficiency was observed in the optimized Cd0.2Zn0.8S@BiOI composites when compared to their single-component counterparts, which may be attributed to increased light absorption and improved electron-hole separation. The photocatalytic mechanism has also been proposed based on the experimental evidences and the theoretical band positions of Cd0.2Zn0.8S@BiOI. PMID:27510184

  16. First steps toward development of a stable isotope forward model for tropical ice cores: cold air incursions and snow days at Quelccaya Ice Cap, Peru

    NASA Astrophysics Data System (ADS)

    Hurley, J. V.; Vuille, M. F.; Hardy, D. R.; Burns, S. J.

    2014-12-01

    We are working towards a forward-model reconstruction of the South American Summer Monsoon (SASM) for the last millennium from the Quelccaya Ice Cap (QIC) d18O record. QIC receives precipitation almost exclusively during the SASM season. Initial efforts focus on dynamics that yield precipitation at this receding tropical ice cap, and how they relate to the hydrogen and oxygen stable isotopes. We present over a decade of daily snow-height change observations from the summit of QIC. Accumulation of snow (~2 m yr-1) at the summit occurs October through April, peaking in December. Net monthly snow-height change is negative May through September, though positive snow height change days do occur throughout the year. Snow height change time-series are used to develop d18O age-models for annual snow collected in vertical profiles near the summit of QIC since 2003. Snow d18O decreases during austral summer from about -17 to -24 per mil VSMOW. Post-depositional alteration of late summer snow during austral winter elevates d18O from about -24 to about -15 per mil VSMOW. Timing of 90thpercentile positive snow-height change events at QIC corresponds with regional precipitation and outgoing longwave radiation (OLR) anomalies that are dynamically triggered by cold air incursions propagating from the midlatitudes east of the Andes into the Amazon Basin. Precipitation and OLR anomalies migrate northwest in about 2-3 days from near Rio de la Plata to central Peru. The convective anomalies are the result of southerly horizontal wind anomalies in the lower troposphere that advect cold extratropical air equatorward. Composite analysis of satellite measurements shows that cold air incursions are associated with negative water vapor dD (~ -40 per mil) anomalies at QIC. We expect that snow stable isotope values from QIC are thus not only records of the deep overturning component of the monsoon circulation but also of synoptic scale monsoon disturbances. Cold air incursions into the South

  17. Atmospheric abundance and global emissions of perfluorocarbons CF4, C2F6 and C3F8 since 1800 inferred from ice core, firn, air archive and in situ measurements

    NASA Astrophysics Data System (ADS)

    Trudinger, Cathy M.; Fraser, Paul J.; Etheridge, David M.; Sturges, William T.; Vollmer, Martin K.; Rigby, Matt; Martinerie, Patricia; Mühle, Jens; Worton, David R.; Krummel, Paul B.; Steele, L. Paul; Miller, Benjamin R.; Laube, Johannes; Mani, Francis S.; Rayner, Peter J.; Harth, Christina M.; Witrant, Emmanuel; Blunier, Thomas; Schwander, Jakob; O'Doherty, Simon; Battle, Mark

    2016-09-01

    Perfluorocarbons (PFCs) are very potent and long-lived greenhouse gases in the atmosphere, released predominantly during aluminium production and semiconductor manufacture. They have been targeted for emission controls under the United Nations Framework Convention on Climate Change. Here we present the first continuous records of the atmospheric abundance of CF4 (PFC-14), C2F6 (PFC-116) and C3F8 (PFC-218) from 1800 to 2014. The records are derived from high-precision measurements of PFCs in air extracted from polar firn or ice at six sites (DE08, DE08-2, DSSW20K, EDML, NEEM and South Pole) and air archive tanks and atmospheric air sampled from both hemispheres. We take account of the age characteristics of the firn and ice core air samples and demonstrate excellent consistency between the ice core, firn and atmospheric measurements. We present an inversion for global emissions from 1900 to 2014. We also formulate the inversion to directly infer emission factors for PFC emissions due to aluminium production prior to the 1980s. We show that 19th century atmospheric levels, before significant anthropogenic influence, were stable at 34.1 ± 0.3 ppt for CF4 and below detection limits of 0.002 and 0.01 ppt for C2F6 and C3F8, respectively. We find a significant peak in CF4 and C2F6 emissions around 1940, most likely due to the high demand for aluminium during World War II, for example for construction of aircraft, but these emissions were nevertheless much lower than in recent years. The PFC emission factors for aluminium production in the early 20th century were significantly higher than today but have decreased since then due to improvements and better control of the smelting process. Mitigation efforts have led to decreases in emissions from peaks in 1980 (CF4) or early-to-mid-2000s (C2F6 and C3F8) despite the continued increase in global aluminium production; however, these decreases in emissions appear to have recently halted. We see a temporary reduction of around

  18. Core Noise Reduction

    NASA Technical Reports Server (NTRS)

    Hultgren, Lennart S.

    2011-01-01

    This presentation is a technical summary of and outlook for NASA-internal and NASA-sponsored external research on core (combustor and turbine) noise funded by the Fundamental Aeronautics Program Subsonic Fixed Wing (SFW) Project. Sections of the presentation cover: the SFW system-level noise metrics for the 2015, 2020, and 2025 timeframes; turbofan design trends and their aeroacoustic implications; the emerging importance of core noise and its relevance to the SFW Reduce-Perceived-Noise Technical Challenge; and the current research activities in the core noise area. Recent work1 on the turbine-transmission loss of combustor noise is briefly described, two2,3 new NRA efforts in the core-noise area are outlined, and an effort to develop CMC-based acoustic liners for broadband noise reduction suitable for turbofan-core application is delineated. The NASA Fundamental Aeronautics Program has the principal objective of overcoming today's national challenges in air transportation. The reduction of aircraft noise is critical to enabling the anticipated large increase in future air traffic. The Subsonic Fixed Wing Project's Reduce-Perceived-Noise Technical Challenge aims to develop concepts and technologies to dramatically reduce the perceived aircraft noise outside of airport boundaries.

  19. LIGHT CURVES OF CORE-COLLAPSE SUPERNOVAE WITH SUBSTANTIAL MASS LOSS USING THE NEW OPEN-SOURCE SUPERNOVA EXPLOSION CODE (SNEC)

    SciTech Connect

    Morozova, Viktoriya; Renzo, Mathieu; Ott, Christian D.; Clausen, Drew; Couch, Sean M.; Ellis, Justin; Roberts, Luke F.; Piro, Anthony L.

    2015-11-20

    We present the SuperNova Explosion Code (SNEC), an open-source Lagrangian code for the hydrodynamics and equilibrium-diffusion radiation transport in the expanding envelopes of supernovae. Given a model of a progenitor star, an explosion energy, and an amount and distribution of radioactive nickel, SNEC generates the bolometric light curve, as well as the light curves in different broad bands assuming blackbody emission. As a first application of SNEC, we consider the explosions of a grid of 15 M{sub ⊙} (at zero-age main sequence, ZAMS) stars whose hydrogen envelopes are stripped to different extents and at different points in their evolution. The resulting light curves exhibit plateaus with durations of ∼20–100 days if ≳1.5–2 M{sub ⊙} of hydrogen-rich material is left and no plateau if less hydrogen-rich material is left. If these shorter plateau lengths are not seen for SNe IIP in nature, it suggests that, at least for ZAMS masses ≲20 M{sub ⊙}, hydrogen mass loss occurs as an all or nothing process. This perhaps points to the important role binary interactions play in generating the observed mass-stripped supernovae (i.e., Type Ib/c events). These light curves are also unlike what is typically seen for SNe IIL, arguing that simply varying the amount of mass loss cannot explain these events. The most stripped models begin to show double-peaked light curves similar to what is often seen for SNe IIb, confirming previous work that these supernovae can come from progenitors that have a small amount of hydrogen and a radius of ∼500 R{sub ⊙}.

  20. Carbon-Coated Core-Shell Fe-Cu Nanoparticles as Highly Active and Durable Electrocatalysts for a Zn-Air Battery.

    PubMed

    Nam, Gyutae; Park, Joohyuk; Choi, Min; Oh, Pilgun; Park, Suhyeon; Kim, Min Gyu; Park, Noejung; Cho, Jaephil; Lee, Jang-Soo

    2015-06-23

    Understanding the interaction between a catalyst and oxygen has been a key step in designing better electrocatalysts for the oxygen reduction reaction (ORR) as well as applying them in metal-air batteries and fuel cells. Alloying has been studied to finely tune the catalysts' electronic structures to afford proper binding affinities for oxygen. Herein, we synthesized a noble-metal-free and nanosized transition metal CuFe alloy encapsulated with a graphitic carbon shell as a highly efficient and durable electrocatalyst for the ORR in alkaline solution. Theoretical models and experimental results demonstrated that the CuFe alloy has a more moderate binding strength for oxygen molecules as well as the final product, OH(-), thus facilitating the oxygen reduction process. Furthermore, the nitrogen-doped graphitic carbon-coated layer, formed catalytically under the influence of iron, affords enhanced charge transfer during the oxygen reduction process and superior durability. These benefits were successfully confirmed by realizing the catalyst application in a mechanically rechargeable Zn-air battery.

  1. Carbon-Coated Core-Shell Fe-Cu Nanoparticles as Highly Active and Durable Electrocatalysts for a Zn-Air Battery.

    PubMed

    Nam, Gyutae; Park, Joohyuk; Choi, Min; Oh, Pilgun; Park, Suhyeon; Kim, Min Gyu; Park, Noejung; Cho, Jaephil; Lee, Jang-Soo

    2015-06-23

    Understanding the interaction between a catalyst and oxygen has been a key step in designing better electrocatalysts for the oxygen reduction reaction (ORR) as well as applying them in metal-air batteries and fuel cells. Alloying has been studied to finely tune the catalysts' electronic structures to afford proper binding affinities for oxygen. Herein, we synthesized a noble-metal-free and nanosized transition metal CuFe alloy encapsulated with a graphitic carbon shell as a highly efficient and durable electrocatalyst for the ORR in alkaline solution. Theoretical models and experimental results demonstrated that the CuFe alloy has a more moderate binding strength for oxygen molecules as well as the final product, OH(-), thus facilitating the oxygen reduction process. Furthermore, the nitrogen-doped graphitic carbon-coated layer, formed catalytically under the influence of iron, affords enhanced charge transfer during the oxygen reduction process and superior durability. These benefits were successfully confirmed by realizing the catalyst application in a mechanically rechargeable Zn-air battery. PMID:25967866

  2. Green synthesis of the reduced graphene oxide-CuI quasi-shell-core nanocomposite: A highly efficient and stable solar-light-induced catalyst for organic dye degradation in water

    NASA Astrophysics Data System (ADS)

    Choi, Jiha; Reddy, D. Amaranatha; Islam, M. Jahurul; Seo, Bora; Joo, Sang Hoon; Kim, Tae Kyu

    2015-12-01

    Surfactant-free, reduced graphene oxide (RGO)-CuI quasi-shell-core nanocomposites were successfully synthesized using ultra-sonication assisted chemical method at room temperature. The morphologies, structures and optical properties of the CuI and CuI-RGO nanocomposites were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier-transformed infrared spectroscopy (FTIR), UV-visible absorption spectroscopy, and photoluminescence (PL) spectroscopy. Morphological and structural analyses indicated that the CuI-RGO core-shell nanocomposites comprise single-crystalline face-centered cubic phase CuI nanostructures, coated with a thin RGO quasi-shell. Photocatalysis experiments revealed that the as-synthesized CuI-RGO nanocomposites exhibit remarkably enhanced photocatalytic activities and stabilities for photo degradation of Rhodamine-B (RhB) organic dye under simulated solar light irradiation. The photo degradation ability is strongly affected by the concentration of RGO in the nanocomposites; the highest photodegradation rate was obtained at a graphene loading content of 2 mg mL-1 nanocomposite. The remarkable photocatalytic performance of the CuI-RGO nanocomposites mainly originates from their unique adsorption and electron-accepting and electron-transporting properties of RGO. The present work provides a novel green synthetic route to producing CuI-RGO nanocomposites without toxic solvents or reducing agents, thereby providing highly efficient and stable solar light-induced RGO-CuI quasi-shell-core nanocomposites for organic dye photo degradation in water.

  3. Core-Noise Research

    NASA Technical Reports Server (NTRS)

    Hultgren, Lennart S.

    2012-01-01

    This presentation is a technical summary of and outlook for NASA-internal and NASA-sponsored external research on core noise funded by the Fundamental Aeronautics Program Subsonic Fixed Wing (SFW) Project. Sections of the presentation cover: the SFW system-level noise metrics for the 2015 (N+1), 2020 (N+2), and 2025 (N+3) timeframes; SFW strategic thrusts and technical challenges; SFW advanced subsystems that are broadly applicable to N+3 vehicle concepts, with an indication where further noise research is needed; the components of core noise (compressor, combustor and turbine noise) and a rationale for NASA's current emphasis on the combustor-noise component; the increase in the relative importance of core noise due to turbofan design trends; the need to understand and mitigate core-noise sources for high-efficiency small gas generators; and the current research activities in the core-noise area, with additional details given about forthcoming updates to NASA's Aircraft Noise Prediction Program (ANOPP) core-noise prediction capabilities, two NRA efforts (Honeywell International, Phoenix, AZ and University of Illinois at Urbana-Champaign, respectively) to improve the understanding of core-noise sources and noise propagation through the engine core, and an effort to develop oxide/oxide ceramic-matrix-composite (CMC) liners for broadband noise attenuation suitable for turbofan-core application. Core noise must be addressed to ensure that the N+3 noise goals are met. Focused, but long-term, core-noise research is carried out to enable the advanced high-efficiency small gas-generator subsystem, common to several N+3 conceptual designs, needed to meet NASA's technical challenges. Intermediate updates to prediction tools are implemented as the understanding of the source structure and engine-internal propagation effects is improved. The NASA Fundamental Aeronautics Program has the principal objective of overcoming today's national challenges in air transportation. The

  4. Facile construction of vertically aligned EuS-ZnO hybrid core shell nanorod arrays for visible light driven photocatalytic properties

    SciTech Connect

    Ranjith, K. S.; Kumar, D. Ranjith; Kumar, R. T. Rajendra

    2015-06-24

    We demonstrated the development of coupled semiconductor in the form of hybrid heterostructures for significant advancement in catalytic functional materials. In this article, we report the preparation of vertically aligned core shell ZnO-EuS nanorod photocatalyst arrays by a simple chemical solution process followed by sulfudation process. The XRD pattern confirmed formation of the hexagonal wurtzite structure of ZnO and cubic nature of the EuS. Cross sectional FESEM images show vertical rod array structure, and the size of the nanorods ranges from 80 to 120 nm. UV-Vis DRS spectra showed that the optical absorption of ZnO was significantly enhanced to the visible region by modification with EuS surfaces. TEM study confirmed that the surface of ZnO was drastically improved by the modification with EuS nanoparticle. The catalytic activity of EuS−ZnO core shell nanorod arrays were evaluated by the photodegradation of Methylene Blue (MB) dye under visible irradiation. The results revealed that the photocatalytic activity of EuS−ZnO was much higher than that of ZnO under natural sunlight. EuS−ZnO was found to be stable and reusable without appreciable loss of catalytic activity up to four consecutive cycles.

  5. Electrical Current Leakage and Open-Core Threading Dislocations in AlGaN-Based Deep Ultraviolet Light-Emitting Diodes.

    SciTech Connect

    Moseley, Michael William; Allerman, Andrew A.; Crawford, Mary H.; Wierer, Jonathan; Smith, Michael L.; Biedermann, Laura

    2014-08-04

    Electrical current transport through leakage paths in AlGaN-based deep ultraviolet (DUV) lightemitting diodes (LEDs) and their effect on LED performance are investigated. Open-core threading dislocations, or nanopipes, are found to conduct current through nominally insulating Al0.7Ga0.3N layers and limit the performance of DUV-LEDs. A defect-sensitive phosphoric acid etch reveals these opencore threading dislocations in the form of large, micron-scale hexagonal etch pits visible with optical microscopy, while closed-core screw-, edge-, and mixed-type threading dislocations are represented by smaller and more numerous nanometer-scale pits visible by atomic-force microscopy. The electrical and optical performances of DUV-LEDs fabricated on similar Si-doped Al0.7Ga0.3N templates are found to have a strong correlation to the density of these nanopipes, despite their small fraction (<0.1% in this study) of the total density of threading dislocations.

  6. Electrical Current Leakage and Open-Core Threading Dislocations in AlGaN-Based Deep Ultraviolet Light-Emitting Diodes.

    DOE PAGES

    Moseley, Michael William; Allerman, Andrew A.; Crawford, Mary H.; Wierer, Jonathan; Smith, Michael L.; Biedermann, Laura

    2014-08-04

    Electrical current transport through leakage paths in AlGaN-based deep ultraviolet (DUV) lightemitting diodes (LEDs) and their effect on LED performance are investigated. Open-core threading dislocations, or nanopipes, are found to conduct current through nominally insulating Al0.7Ga0.3N layers and limit the performance of DUV-LEDs. A defect-sensitive phosphoric acid etch reveals these opencore threading dislocations in the form of large, micron-scale hexagonal etch pits visible with optical microscopy, while closed-core screw-, edge-, and mixed-type threading dislocations are represented by smaller and more numerous nanometer-scale pits visible by atomic-force microscopy. The electrical and optical performances of DUV-LEDs fabricated on similar Si-doped Al0.7Ga0.3N templatesmore » are found to have a strong correlation to the density of these nanopipes, despite their small fraction (<0.1% in this study) of the total density of threading dislocations.« less

  7. NaYF{sub 4}:Er,Yb/Bi{sub 2}MoO{sub 6} core/shell nanocomposite: A highly efficient visible-light-driven photocatalyst utilizing upconversion

    SciTech Connect

    Sun, Yuanyuan; Wang, Wenzhong Sun, Songmei; Zhang, Ling

    2014-04-01

    Highlights: • Design and synthesis of NaYF{sub 4}:Er,Yb/Bi{sub 2}MoO{sub 6} based on upconversion. • NaYF{sub 4}:Er,Yb/Bi{sub 2}MoO{sub 6} nanocomposite was prepared for the first time. • Core–shell structure benefits the properties. • Upconversion contributed to the enhanced photocatalytic activity. • Helps to understand the functionality of new type photocatalysts. - Abstract: NaYF{sub 4}:Er,Yb/Bi{sub 2}MoO{sub 6} core/shell nanocomposite was designed and prepared for the first time based on upconversion. The products were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), high resolution TEM (HRTEM), energy dispersive X-ray spectroscopy (EDS) and diffuse reflectance spectra (DRS). The results revealed that the as-synthesized NaYF{sub 4}:Er,Yb/Bi{sub 2}MoO{sub 6} consisted of spheres with a core diameter of about 26 nm and a shell diameter of around 6 nm. The core was upconversion illuminant NaYF{sub 4}:Er,Yb and the shell was Bi{sub 2}MoO{sub 6} around the core, which was confirmed by EDS. The NaYF{sub 4}:Er,Yb/Bi{sub 2}MoO{sub 6} exhibited higher photocatalytic activity for the photodecomposition of Rhodamine B (RhB) under the irradiation of Xe lamp and green light emitting diode (g-LED). The mechanism of the high photocatalytic activity was discussed by photoluminescence spectra (PL), which is mainly attributed to upconversion of NaYF{sub 4}:Er,Yb in the NaYF{sub 4}:Er,Yb/Bi{sub 2}MoO{sub 6} nanocomposite and the core–shell structure.

  8. Design of a circular photonic crystal fiber with flattened chromatic dispersion using a defected core and selectively reduced air holes: Application to supercontinuum generation at 1.55 μm

    NASA Astrophysics Data System (ADS)

    Medjouri, Abdelkader; Simohamed, Lotfy Mokhtar; Ziane, Omar; Boudrioua, Azzedine; Becer, Zoubir

    2015-08-01

    In this paper, we present and numerically investigate a new and simple design of Circular Lattice Photonic Crystal Fiber (CL-PCF) with near zero ultra-flattened chromatic dispersion. The near zero dispersion is obtained by introducing a defect into the solid core and the dispersion flatness is achieved by appropriately reducing the diameter of the core-neighboring air holes ring. Simulations are performed by using the finite-difference frequency-domain (FDFD) method combined with the perfectly matched layer (PML) boundary condition. Results show that an ultra-flattened chromatic dispersion as small as ±0.66 ps/nm km is obtained over a broad band of 400 nm with high nonlinearity and ultra-low confinement loss. Furthermore, the supercontinuum (SC) generation over a short length of the proposed CL-PCF is numerically investigated. Results indicate that flat SC spectrum with a Full Width at Half Maximum (FWHM) of 600 nm is achieved with 25 cm of fiber length.

  9. One-dimensional mesoporous Fe2O3@TiO2 core-shell nanocomposites: Rational design, synthesis and application as high-performance photocatalyst in visible and UV light region

    NASA Astrophysics Data System (ADS)

    Zhang, Xiao; Xie, Yaping; Chen, Haoxin; Guo, Jinxue; Meng, Alan; Li, Chunfang

    2014-10-01

    An ideal photocatalyst for degradation of organic pollutants should combine the features of efficient visible light response, fast electron transport, high electron-hole separation efficiency, and large specific surface area. However, these requirements usually cannot be achieved simultaneously in the present state-of-the-art research. In this work, we develop a rational synthesis strategy for the preparation of one-dimensional (1D) mesoporous Fe2O3@TiO2 core-shell composites. In this strategy, FeOOH nanorods are firstly coated by TiO2 shell, followed by a calcination process. The as-prepared composites are thoroughly investigated with X-ray powder diffraction, scanning electron microscope, energy dispersive spectroscopy, transmission electron microscope, N2 adsorption-desorption isotherms, UV-visible diffuse-reflectance spectra, and photoluminescence spectra. Endowed with the advantages of its composition and specific structural features, the presented sample possesses the combined advantages mentioned above, thus delivering evidently enhanced photocatalytic activity for the degradation of methyl orange under UV light irradiation and Rhodamine B under visible light irradiation. And the possible mechanism of the enhanced photocatalytic performance is proposed.

  10. Nanofocus x-ray diffraction and cathodoluminescence investigations into individual core-shell (In,Ga)N/GaN rod light-emitting diodes

    NASA Astrophysics Data System (ADS)

    Krause, Thilo; Hanke, Michael; Cheng, Zongzhe; Niehle, Michael; Trampert, Achim; Rosenthal, Martin; Burghammer, Manfred; Ledig, Johannes; Hartmann, Jana; Zhou, Hao; Wehmann, Hergo-Heinrich; Waag, Andreas

    2016-08-01

    Employing nanofocus x-ray diffraction, we investigate the local strain field induced by a five-fold (In,Ga)N multi-quantum well embedded into a GaN micro-rod in core-shell geometry. Due to an x-ray beam width of only 150 nm in diameter, we are able to distinguish between individual m-facets and to detect a significant in-plane strain gradient along the rod height. This gradient translates to a red-shift in the emitted wavelength revealed by spatially resolved cathodoluminescence measurements. We interpret the result in terms of numerically derived in-plane strain using the finite element method and subsequent kinematic scattering simulations which show that the driving parameter for this effect is an increasing indium content towards the rod tip.

  11. Au@Cu2O stellated polytope with core-shelled nanostructure for high-performance adsorption and visible-light-driven photodegradation of cationic and anionic dyes.

    PubMed

    Wu, Xueqing; Cai, Jiabai; Li, Shunxing; Zheng, Fengying; Lai, Zhanghua; Zhu, Licong; Chen, Tanju

    2016-05-01

    Au nanoparticles were covered by Cu2O nanoparticles shell and then Au@Cu2O stellated polytope was synthesized by a facile aqueous solution approach. The samples were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction patterns, X-ray photoelectron spectroscopy, Brunner-Emmet-Teller measurements, and Ultraviolet-visible spectroscopy analysis. With good aqueous dispersibility, surface positive charge, and high chemisorption capacity, Au@Cu2O could be used for anionic dyes removal. Compared with Degussa P25-TiO2, the adsorption of anionic dyes (acid violet 43 or methyl blue, 5.0 mg L(-1)) onto Au@Cu2O was increased by 90.12% and 50.8%, respectively. The photodegradation activity of methyl orange and methyl violet were in the declining order: Au@Cu2O>Cu2O-Au nanocomposites>Cu2O>P25-TiO2. The synergistic effect of coupling Au core with Cu2O shell on the dyes photodegradation was observed. The photoexcited electrons from Cu2O conduction band could be captured by Au nanoparticles, resulting in an improved electron-hole separation. Moreover, a Schottky barrier was assumed to form at the Cu2O-Au interface and Au NPs as electron sink could reduce the recombination of photoinduced electrons and holes, facilitating the photocatalytic interface reaction. The geometry of core-shell and stellated polytope is effective in the design of Cu2O-Au nanocomposites for adsorption and photocatalysis. PMID:26874979

  12. Cu2-xSe@mSiO2-PEG core-shell nanoparticles: a low-toxic and efficient difunctional nanoplatform for chemo-photothermal therapy under near infrared light radiation with a safe power density

    NASA Astrophysics Data System (ADS)

    Liu, Xijian; Wang, Qian; Li, Chun; Zou, Rujia; Li, Bo; Song, Guosheng; Xu, Kaibing; Zheng, Yun; Hu, Junqing

    2014-03-01

    A low-toxic difunctional nanoplatform integrating both photothermal therapy and chemotherapy for killing cancer cells using Cu2-xSe@mSiO2-PEG core-shell nanoparticles is reported. Silica coating and further PEG modification improve the hydrophilicity and biocompatibility of copper selenide nanoparticles. As-prepared Cu2-xSe@mSiO2-PEG nanoparticles not only display strong near infrared (NIR) region absorption and good photothermal effect, but also exhibit excellent biocompatibility. The mesoporous silica shell is provided as the carrier for loading the anticancer drug, doxorubicin (DOX). Moreover, the release of DOX from Cu2-xSe@mSiO2-PEG core-shell nanoparticles can be triggered by pH and NIR light, resulting in a synergistic effect for killing cancer cells. Importantly, the combination of photothermal therapy and chemotherapy driven by NIR radiation with safe power density significantly improves the therapeutic efficacy, and demonstrates better therapeutic effects for cancer treatment than individual therapy.A low-toxic difunctional nanoplatform integrating both photothermal therapy and chemotherapy for killing cancer cells using Cu2-xSe@mSiO2-PEG core-shell nanoparticles is reported. Silica coating and further PEG modification improve the hydrophilicity and biocompatibility of copper selenide nanoparticles. As-prepared Cu2-xSe@mSiO2-PEG nanoparticles not only display strong near infrared (NIR) region absorption and good photothermal effect, but also exhibit excellent biocompatibility. The mesoporous silica shell is provided as the carrier for loading the anticancer drug, doxorubicin (DOX). Moreover, the release of DOX from Cu2-xSe@mSiO2-PEG core-shell nanoparticles can be triggered by pH and NIR light, resulting in a synergistic effect for killing cancer cells. Importantly, the combination of photothermal therapy and chemotherapy driven by NIR radiation with safe power density significantly improves the therapeutic efficacy, and demonstrates better therapeutic

  13. Core-Noise

    NASA Technical Reports Server (NTRS)

    Hultgren, Lennart S.

    2010-01-01

    This presentation is a technical progress report and near-term outlook for NASA-internal and NASA-sponsored external work on core (combustor and turbine) noise funded by the Fundamental Aeronautics Program Subsonic Fixed Wing (SFW) Project. Sections of the presentation cover: the SFW system level noise metrics for the 2015, 2020, and 2025 timeframes; the emerging importance of core noise and its relevance to the SFW Reduced-Noise-Aircraft Technical Challenge; the current research activities in the core-noise area, with some additional details given about the development of a high-fidelity combustion-noise prediction capability; the need for a core-noise diagnostic capability to generate benchmark data for validation of both high-fidelity work and improved models, as well as testing of future noise-reduction technologies; relevant existing core-noise tests using real engines and auxiliary power units; and examples of possible scenarios for a future diagnostic facility. The NASA Fundamental Aeronautics Program has the principal objective of overcoming today's national challenges in air transportation. The SFW Reduced-Noise-Aircraft Technical Challenge aims to enable concepts and technologies to dramatically reduce the perceived aircraft noise outside of airport boundaries. This reduction of aircraft noise is critical for enabling the anticipated large increase in future air traffic. Noise generated in the jet engine core, by sources such as the compressor, combustor, and turbine, can be a significant contribution to the overall noise signature at low-power conditions, typical of approach flight. At high engine power during takeoff, jet and fan noise have traditionally dominated over core noise. However, current design trends and expected technological advances in engine-cycle design as well as noise-reduction methods are likely to reduce non-core noise even at engine-power points higher than approach. In addition, future low-emission combustor designs could increase

  14. Effect of air temperature and relative humidity at various fuel-air ratios on exhaust emissions on a per-mode basis of an Avco Lycoming 0-320 DIAD light aircraft engine. Volume 2: Individual data points

    NASA Technical Reports Server (NTRS)

    Skorobatckyi, M.; Cosgrove, D. V.; Meng, P. R.; Kempke, E. R.

    1976-01-01

    A carbureted four cylinder air cooled 0-320 DIAD Lycoming aircraft engine was tested to establish the effects of air temperature and humidity at various fuel-air ratios on the exhaust emissions on a per-mode basis. The test conditions included carburetor lean-out at air temperatures of 50, 59, 80, and 100 F at relative humidities of 0, 30, 60, and 80 percent. Temperature-humidity effects at the higher values of air temperature and relative humidity tested indicated that the HC and CO emissions increased significantly, while the NOx emissions decreased. Even at a fixed fuel-air ratio, the HC emissions increase and the NOx emissions decrease at the higher values of air temperature and humidity. Volume II contains the data taken at each of the individual test points.

  15. Effect of Air Temperature and Relative Humidity at Various Fuel-Air Ratios on Exhaust Emissions on a Per-Mode Basis of an AVCO Lycoming 0-320 Diad Light Aircraft Engine: Volume 1: Results and Plotted Data

    NASA Technical Reports Server (NTRS)

    Skorobatckyi, M.; Cosgrove, D. V.; Meng, P. R.; Kempe, E. E., Jr.

    1978-01-01

    A carbureted four cylinder air cooled 0-320 DIAD Lycoming aircraft engine was tested to establish the effects of air temperature and humidity at various fuel-air ratios on the exhaust emissions on a per-mode basis. The test conditions include carburetor lean out at air temperatures of 50, 59, 80, and 100 F at relative humidities of 0, 30, 60, and 80 percent. Temperature humidity effects at the higher values of air temperature and relative humidity tested indicated that the HC and CO emissions increased significantly, while the NOx emissions decreased. Even at a fixed fuel air ratio, the HC emissions increase and the NOx emissions decrease at the higher values of air temperature and humidity.

  16. Scaling To A Million Cores And Beyond: Using Light-Weight Simulation to Understand The Challenges Ahead On The Road To Exascale

    SciTech Connect

    Engelmann, Christian

    2014-01-01

    As supercomputers scale to 1,000 PFlop/s over the next decade, investigating the performance of parallel applications at scale on future architectures and the performance impact of different architecture choices for high-performance computing (HPC) hardware/software co-design is crucial. This paper summarizes recent efforts in designing and implementing a novel HPC hardware/software co-design toolkit. The presented Extreme-scale Simulator (xSim) permits running an HPC application in a controlled environment with millions of concurrent execution threads while observing its performance in a simulated extreme-scale HPC system using architectural models and virtual timing. This paper demonstrates the capabilities and usefulness of the xSim performance investigation toolkit, such as its scalability to 2^27 simulated Message Passing Interface (MPI) ranks on 960 real processor cores, the capability to evaluate the performance of different MPI collective communication algorithms, and the ability to evaluate the performance of a basic Monte Carlo application with different architectural parameters.

  17. Strong photonic crystal behavior in regular arrays of core-shell and quantum disc InGaN/GaN nanorod light-emitting diodes

    SciTech Connect

    Lewins, C. J. Le Boulbar, E. D.; Lis, S. M.; Shields, P. A.; Allsopp, D. W. E.; Edwards, P. R.; Martin, R. W.

    2014-07-28

    We show that arrays of emissive nanorod structures can exhibit strong photonic crystal behavior, via observations of the far-field luminescence from core-shell and quantum disc InGaN/GaN nanorods. The conditions needed for the formation of directional Bloch modes characteristic of strong photonic behavior are found to depend critically upon the vertical shape of the nanorod sidewalls. Index guiding by a region of lower volume-averaged refractive index near the base of the nanorods creates a quasi-suspended photonic crystal slab at the top of the nanorods which supports Bloch modes. Only diffractive behavior could be observed without this region. Slab waveguide modelling of the vertical structure shows that the behavioral regime of the emissive nanorod arrays depends strongly upon the optical coupling between the nanorod region and the planar layers below. The controlled crossover between the two regimes of photonic crystal operation enables the design of photonic nanorod structures formed on planar substrates that exploit either behavior depending on device requirements.

  18. Evaluating the Use of MODIS AOD for Air Quality Determination by Comparison with the Vertical Distribution of Aerosol Light Scattering Coefficient Obtained with a Balloon-Borne Nephelometer

    NASA Astrophysics Data System (ADS)

    Sumlin, B.; Arnott, W. P.; Moosmuller, H.

    2012-12-01

    The MODIS instruments aboard the Aqua and Terra satellites provide aerosol optical depth information for the entire Earth on a daily basis. Ideally, satellite measurements should correlate with ground-based measurements in order to be useful for air quality applications. Reno, Nevada, USA is a high desert city situated in the Great Basin. Its unique geography and proximity to urban and biomass burning aerosol sources make it an ideal candidate for aerosol research. In August 2011, the Reno Aerosol Characterization Experiment measured atmospheric aerosols with a ground-based Cimel CE-318 sun-photometer and in situ photoacoustic instrumentation to quantify aerosol concentrations at the surface and in the column. However, the results of these measurements indicated the existence of a more complex system of aerosol mixing above the atmospheric boundary layer than previously thought. In order to validate these measurements, an autonomous suite of instrumentation has been developed. This device is carried aloft by a weather balloon and utilizes a reciprocal nephelometer to obtain a high-resolution profile of the vertical distribution of aerosol light scattering coefficient, as well as instrumentation to record atmospheric variables such as temperature, pressure, relative humidity, and dew point. Position, course, speed, and altitude are logged with an onboard GPS module and correlated with atmospheric and aerosol measurements. Presented is the design and development of this new instrument, its comparison with proven laboratory instruments, data gathered from flights during August-November 2012, and its comparison to ground-based measurements and satellite data from the MODIS instruments.

  19. Core Noise - Increasing Importance

    NASA Technical Reports Server (NTRS)

    Hultgren, Lennart S.

    2011-01-01

    This presentation is a technical summary of and outlook for NASA-internal and NASA-sponsored external research on core (combustor and turbine) noise funded by the Fundamental Aeronautics Program Subsonic Fixed Wing (SFW) Project. Sections of the presentation cover: the SFW system-level noise metrics for the 2015, 2020, and 2025 timeframes; turbofan design trends and their aeroacoustic implications; the emerging importance of core noise and its relevance to the SFW Reduced-Perceived-Noise Technical Challenge; and the current research activities in the core-noise area, with additional details given about the development of a high-fidelity combustor-noise prediction capability as well as activities supporting the development of improved reduced-order, physics-based models for combustor-noise prediction. The need for benchmark data for validation of high-fidelity and modeling work and the value of a potential future diagnostic facility for testing of core-noise-reduction concepts are indicated. The NASA Fundamental Aeronautics Program has the principal objective of overcoming today's national challenges in air transportation. The SFW Reduced-Perceived-Noise Technical Challenge aims to develop concepts and technologies to dramatically reduce the perceived aircraft noise outside of airport boundaries. This reduction of aircraft noise is critical to enabling the anticipated large increase in future air traffic. Noise generated in the jet engine core, by sources such as the compressor, combustor, and turbine, can be a significant contribution to the overall noise signature at low-power conditions, typical of approach flight. At high engine power during takeoff, jet and fan noise have traditionally dominated over core noise. However, current design trends and expected technological advances in engine-cycle design as well as noise-reduction methods are likely to reduce non-core noise even at engine-power points higher than approach. In addition, future low-emission combustor

  20. Outer-core compositional stratification from observed core wave speed profiles.

    PubMed

    Helffrich, George; Kaneshima, Satoshi

    2010-12-01

    Light elements must be present in the nearly pure iron core of the Earth to match the remotely observed properties of the outer and inner cores. Crystallization of the inner core excludes light elements from the solid, concentrating them in liquid near the inner-core boundary that potentially rises and collects at the top of the core, and this may have a seismically observable signal. Here we present array-based observations of seismic waves sensitive to this part of the core whose wave speeds require there to be radial compositional variation in the topmost 300 km of the outer core. The velocity profile significantly departs from that of compression of a homogeneous liquid. Total light-element enrichment is up to five weight per cent at the top of the core if modelled in the Fe-O-S system. The stratification suggests the existence of a subadiabatic temperature gradient at the top of the outer core. PMID:21150995

  1. Optical fiber sensor having a sol-gel fiber core and a method of making

    DOEpatents

    Tao, Shiquan; Jindal, Rajeev; Winstead, Christopher; Singh, Jagdish P.

    2006-06-06

    A simple, economic wet chemical procedure is described for making sol-gel fibers. The sol-gel fibers made from this process are transparent to ultraviolet, visible and near infrared light. Light can be guided in these fibers by using an organic polymer as a fiber cladding. Alternatively, air can be used as a low refractive index medium. The sol-gel fibers have a micro pore structure which allows molecules to diffuse into the fiber core from the surrounding environment. Chemical and biochemical reagents can be doped into the fiber core. The sol-gel fiber can be used as a transducer for constructing an optical fiber sensor. The optical fiber sensor having an active sol-gel fiber core is more sensitive than conventional evanescent wave absorption based optical fiber sensors.

  2. Aluminum plasmonics for enhanced visible light absorption and high efficiency water splitting in core-multishell nanowire photoelectrodes with ultrathin hematite shells.

    PubMed

    Ramadurgam, Sarath; Lin, Tzu-Ging; Yang, Chen

    2014-08-13

    The poor internal quantum efficiency (IQE) arising from high recombination and insufficient absorption is one of the critical challenges toward achieving high efficiency water splitting in hematite (α-Fe2O3) photoelectrodes. By combining the nanowire (NW) geometry with the localized surface plasmon resonance (LSPR) in semiconductor-metal-metal oxide core-multishell (CMS) NWs, we theoretically demonstrate an effective route to strongly improve absorption within ultrathin (sub-50 nm) hematite layers. We show that Si-Al-Fe2O3 CMS NWs exhibit photocurrent densities comparable to Si-Ag-Fe2O3 CMS and outperform Fe2O3, Si-Fe2O3 CS and Si-Au-Fe2O3 CMS NWs. Specifically; Si-Al-Fe2O3 CMS NWs reach photocurrent densities of ∼ 11.81 mA/cm(2) within a 40 nm thick hematite shell which corresponding to a solar to hydrogen (STH) efficiency of 14.5%. This corresponds to about 93% of the theoretical maximum for bulk hematite. Therefore, we establish Al as an excellent alternative plasmonic material compared to precious metals in CMS structures. Further, the absorbed photon flux is close to the NW surface in the CMS NWs, which ensures the charges generated can reach the reaction site with minimal recombining. Although the NW geometry is anisotropic, the CMS NWs exhibit polarization independent absorption over a large range of incidence angles. Finally, we show that Si-Al-Fe2O3 CMS NWs demonstrate photocurrent densities greater than ∼ 8.2 mA/cm(2) (STH efficiency of 10%) for incidence angles as large as 45°. These theoretical results strongly establish the effectiveness of the Al-based CMS NWs for achieving scalable and cost-effective photoelectrodes with improved IQE, enabling a novel route toward high efficiency water splitting.

  3. U.S. Department of Energy, National Energy Technology Laboratory Solid-State Lighting Core Technologies Light Emitting Diodes on Semipolar Bulk GaN Substrate with IQE > 80% at 150 A/cm2 and 100 0C

    SciTech Connect

    Chakraborty, Arpan; David, Aurelien; Grundmann, Michael; Tyagi, Anurag; Craven, Michael; Hurni, Christophe; Cich, Michael

    2015-03-31

    GaN is a crucial material for light-emitting diodes (LEDs) emitting in the violet-to-green range. Despite its good performance, it still suffers from significant technical limitations. In particular, the efficiency of GaN-based LEDs decreases at high current (“current droop”) and high temperature (“temperature droop”). This is problematic in some lighting applications, where a high-power operation is required. This program studied the use of particular substrates to improve the efficiency of GaN-based LEDs: bulk semipolar (SP) GaN substrates. These substrates possess a very high material quality, and physical properties which are distinctly different from legacy substrates currently used in the LED industry. The program focused on the development of accurate metrology to quantify the performance of GaN-based LEDs, and on improvement to LED quality and design on SP substrates. Through a thorough optimization process, we demonstrated violet LEDs with very high internal quantum efficiency, exceeding 85% at high temperature and high current. We also investigated longer-wavelength blue emitters, but found that the limited strain budget was a key limitation.

  4. 24. A CORE WORKER DISPLAYS THE CORE BOX AND CORES ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    24. A CORE WORKER DISPLAYS THE CORE BOX AND CORES FOR A BRASS GATE VALVE BODY MADE ON A CORE BOX, CA. 1950. - Stockham Pipe & Fittings Company, 4000 Tenth Avenue North, Birmingham, Jefferson County, AL

  5. Band engineered epitaxial 3D GaN-InGaN core-shell rod arrays as an advanced photoanode for visible-light-driven water splitting.

    PubMed

    Caccamo, Lorenzo; Hartmann, Jana; Fàbrega, Cristian; Estradé, Sonia; Lilienkamp, Gerhard; Prades, Joan Daniel; Hoffmann, Martin W G; Ledig, Johannes; Wagner, Alexander; Wang, Xue; Lopez-Conesa, Lluis; Peiró, Francesca; Rebled, José Manuel; Wehmann, Hergo-Heinrich; Daum, Winfried; Shen, Hao; Waag, Andreas

    2014-02-26

    3D single-crystalline, well-aligned GaN-InGaN rod arrays are fabricated by selective area growth (SAG) metal-organic vapor phase epitaxy (MOVPE) for visible-light water splitting. Epitaxial InGaN layer grows successfully on 3D GaN rods to minimize defects within the GaN-InGaN heterojunctions. The indium concentration (In ∼ 0.30 ± 0.04) is rather homogeneous in InGaN shells along the radial and longitudinal directions. The growing strategy allows us to tune the band gap of the InGaN layer in order to match the visible absorption with the solar spectrum as well as to align the semiconductor bands close to the water redox potentials to achieve high efficiency. The relation between structure, surface, and photoelectrochemical property of GaN-InGaN is explored by transmission electron microscopy (TEM), electron energy loss spectroscopy (EELS), Auger electron spectroscopy (AES), current-voltage, and open circuit potential (OCP) measurements. The epitaxial GaN-InGaN interface, pseudomorphic InGaN thin films, homogeneous and suitable indium concentration and defined surface orientation are properties demanded for systematic study and efficient photoanodes based on III-nitride heterojunctions. PMID:24517402

  6. Honeycomb Core Permeability Under Mechanical Loads

    NASA Technical Reports Server (NTRS)

    Glass, David E.; Raman, V. V.; Venkat, Venki S.; Sankaran, Sankara N.

    1997-01-01

    A method for characterizing the air permeability of sandwich core materials as a function of applied shear stress was developed. The core material for the test specimens was either Hexcel HRP-3/16-8.0 and or DuPont Korex-1/8-4.5 and was nominally one-half inch thick and six inches square. The facesheets where made of Hercules' AS4/8552 graphite/epoxy (Gr/Ep) composites and were nominally 0.059-in. thick. Cytec's Metalbond 1515-3M epoxy film adhesive was used for co-curing the facesheets to the core. The permeability of the specimens during both static (tension) and dynamic (reversed and non-reversed) shear loads were measured. The permeability was measured as the rate of air flow through the core from a circular 1-in2 area of the core exposed to an air pressure of 10.0 psig. In both the static and dynamic testing, the Korex core experienced sudden increases in core permeability corresponding to a core catastrophic failure, while the URP core experienced a gradual increase in the permeability prior to core failure. The Korex core failed at lower loads than the HRP core both in the transverse and ribbon directions.

  7. Towards high efficiency air-processed near-infrared responsive photovoltaics: bulk heterojunction solar cells based on PbS/CdS core-shell quantum dots and TiO2 nanorod arrays.

    PubMed

    Gonfa, Belete Atomsa; Kim, Mee Rahn; Delegan, Nazar; Tavares, Ana C; Izquierdo, Ricardo; Wu, Nianqiang; El Khakani, My Ali; Ma, Dongling

    2015-06-14

    Near infrared (NIR) PbS quantum dots (QDs) have attracted significant research interest in solar cell applications as they offer several advantages, such as tunable band gaps, capability of absorbing NIR photons, low cost solution processability and high potential for multiple exciton generation. Nonetheless, reports on solar cells based on NIR PbS/CdS core-shell QDs, which are in general more stable and better passivated than PbS QDs and thus more promising for solar cell applications, remain very rare. Herein we report high efficiency bulk heterojunction QD solar cells involving hydrothermally grown TiO2 nanorod arrays and PbS/CdS core-shell QDs processed in air (except for a device thermal annealing step) with a photoresponse extended to wavelengths >1200 nm and with a power conversion efficiency (PCE) as high as 4.43%. This efficiency was achieved by introducing a thin, sputter-deposited, uniform TiO2 seed layer to improve the interface between the TiO2 nanorod arrays and the front electrode, by optimizing TiO2 nanorod length and by conducting QD annealing treatment to enhance charge carrier transport. It was found that the effect of the seed layer became more obvious when the TiO2 nanorods were longer. Although photocurrent did not change much, both open circuit voltage and fill factor clearly changed with TiO2 nanorod length. This was mainly attributed to the variation of charge transport and recombination processes, as evidenced by series and shunt resistance studies. The optimal PCE was obtained at the nanorod length of ∼450 nm. Annealing is shown to further increase the PCE by ∼18%, because of the improvement of charge carrier transport in the devices as evidenced by considerably increased photocurrent. Our results clearly demonstrate the potential of the PbS/CdS core-shell QDs for the achievement of high PCE, solution processable and NIR responsive QD solar cells.

  8. Controlling Light Harvesting with Light.

    PubMed

    Gwizdala, Michal; Berera, Rudi; Kirilovsky, Diana; van Grondelle, Rienk; Krüger, Tjaart P J

    2016-09-14

    When exposed to intense sunlight, all organisms performing oxygenic photosynthesis implement various photoprotective strategies to prevent potentially lethal photodamage. The rapidly responding photoprotective mechanisms, occurring in the light-harvesting pigment-protein antennae, take effect within tens of seconds, while the dramatic and potentially harmful light intensity fluctuations manifest also on shorter time scales. Here we show that, upon illumination, individual phycobilisomes from Synechocystis PCC 6803, which, in vivo under low-light conditions, harvest solar energy, and have the built-in capacity to switch rapidly and reversibly into light-activated energy-dissipating states. Simultaneously measured fluorescence intensity, lifetime, and spectra, compared with a multicompartmental kinetic model, revealed that essentially any subunit of a phycobilisome can be quenched, and that the core complexes were targeted most frequently. Our results provide the first evidence for fluorescence blinking from a biologically active system at physiological light intensities and suggest that the light-controlled switches to intrinsically available energy-dissipating states are responsible for a novel type of photoprotection in cyanobacteria. We anticipate other photosynthetic organisms to employ similar strategies to respond instantly to rapid solar light intensity fluctuations. A detailed understanding of the photophysics of photosynthetic antenna complexes is of great interest for bioinspired solar energy technologies. PMID:27546794

  9. Controlling Light Harvesting with Light.

    PubMed

    Gwizdala, Michal; Berera, Rudi; Kirilovsky, Diana; van Grondelle, Rienk; Krüger, Tjaart P J

    2016-09-14

    When exposed to intense sunlight, all organisms performing oxygenic photosynthesis implement various photoprotective strategies to prevent potentially lethal photodamage. The rapidly responding photoprotective mechanisms, occurring in the light-harvesting pigment-protein antennae, take effect within tens of seconds, while the dramatic and potentially harmful light intensity fluctuations manifest also on shorter time scales. Here we show that, upon illumination, individual phycobilisomes from Synechocystis PCC 6803, which, in vivo under low-light conditions, harvest solar energy, and have the built-in capacity to switch rapidly and reversibly into light-activated energy-dissipating states. Simultaneously measured fluorescence intensity, lifetime, and spectra, compared with a multicompartmental kinetic model, revealed that essentially any subunit of a phycobilisome can be quenched, and that the core complexes were targeted most frequently. Our results provide the first evidence for fluorescence blinking from a biologically active system at physiological light intensities and suggest that the light-controlled switches to intrinsically available energy-dissipating states are responsible for a novel type of photoprotection in cyanobacteria. We anticipate other photosynthetic organisms to employ similar strategies to respond instantly to rapid solar light intensity fluctuations. A detailed understanding of the photophysics of photosynthetic antenna complexes is of great interest for bioinspired solar energy technologies.

  10. Guiding properties of kagome-lattice hollow-core fibers

    NASA Astrophysics Data System (ADS)

    Coscelli, E.; Poli, F.; Passaro, D.; Cucinotta, A.; Selleri, S.

    2010-04-01

    Photonic crystal fibers with kagome lattice are a particular kind of micostructured hollow-core fibers whose cross-section is characterized by a web of thin silica struts intersecting in a Star-of-David pattern. Such fibers show unusual properties, such as light confinement in the air-core in absence of a full photonic bandgap. The primary design parameter for such fibers is the strut thickness, which is responsible for the position and the width of the transmission bands. In this paper the guiding properties of hollow-core photonic crystal fibers with kagome lattice are investigated by means of a full-vector modal solver based on the finite element method. The fundamental mode effective index and confinement loss have been evaluated in a wide wavelength range, spanning from 300 nm to 1600 nm, accounting for the influence of the silica strut width on the transmission window. Moreover, the effects of selective alteration of the width and the shape of the silica struts surrounding the core have been analyzed. Simulation results show that the core-surrounding silica ring has the strongest effect on the transmission band, the loss level and the resonance wavelength position and, consequently, it should be carefully controlled during the fiber fabrication.

  11. Enhanced waveguide-type ultraviolet electroluminescence from ZnO/MgZnO core/shell nanorod array light-emitting diodes via coupling with Ag nanoparticles localized surface plasmons

    NASA Astrophysics Data System (ADS)

    Zhang, Cen; Marvinney, Claire Elizabeth; Xu, Hai Yang; Liu, Wei Zhen; Wang, Chun Liang; Zhang, Li Xia; Wang, Jian Nong; Ma, Jian Gang; Liu, Yi Chun

    2014-12-01

    Localized surface plasmon (LSP) enhanced waveguide-type ultraviolet light-emitting diodes (LEDs) were fabricated by sputtering Ag nanoparticles (Ag-NPs) onto ZnO/MgZnO core/shell nanorod array (CS-NRA)/p-GaN heterostructures. A ~9-fold enhancement of ZnO ultraviolet electroluminescence (EL) was demonstrated by the Ag-NPs decorated LED compared with the device without Ag-NPs. Angle-dependent EL measurements, as well as finite-difference time-domain simulations of the EL intensity spatial distribution, confirmed the waveguide-type EL transmission mode along the NR's axial direction. The increased spontaneous emission rate observed in time-resolved spectroscopy suggested that the ZnO EL enhancement was attributed to LSP-exciton/polariton coupling. However, a direct coupling is very difficult to achieve between Ag-LSPs and electron-hole pairs in the active region due to their ``remote'' separation. Thereby, two possible models involving the dynamic process of interactions among excitons, photons, and LSPs, were established to understand the selective enhancement of ZnO EL.Localized surface plasmon (LSP) enhanced waveguide-type ultraviolet light-emitting diodes (LEDs) were fabricated by sputtering Ag nanoparticles (Ag-NPs) onto ZnO/MgZnO core/shell nanorod array (CS-NRA)/p-GaN heterostructures. A ~9-fold enhancement of ZnO ultraviolet electroluminescence (EL) was demonstrated by the Ag-NPs decorated LED compared with the device without Ag-NPs. Angle-dependent EL measurements, as well as finite-difference time-domain simulations of the EL intensity spatial distribution, confirmed the waveguide-type EL transmission mode along the NR's axial direction. The increased spontaneous emission rate observed in time-resolved spectroscopy suggested that the ZnO EL enhancement was attributed to LSP-exciton/polariton coupling. However, a direct coupling is very difficult to achieve between Ag-LSPs and electron-hole pairs in the active region due to their ``remote'' separation

  12. Evaluation of Air Pollution Applications of AERONET and MODIS Aerosol Column Optical Depth by Comparison with In Situ Measurements of Aerosol Light Scattering and Absorption for Reno, NV, USA

    NASA Astrophysics Data System (ADS)

    Loria Salazar, S.; Arnott, W. P.; Moosmuller, H.; Colucci, D.

    2012-12-01

    Reno, Nevada, USA is subject to typical urban aerosol, wind-blown dust, and occasional biomass burning smoke from anthropogenic and natural fires. Reno has complex air flow at levels relevant for aerosol transport. At times recirculating mountain and urban flow arrives from the Sierra Nevada, San Francisco, CA and Sacramento, CA. The urban plumes are further modified by biogenic forest emissions and secondary aerosol formation during transport over the Sierra Nevada Mountains to Reno. This complicates the use of MODIS aerosol optical depth (AOD) for air quality measurements in Reno. Our laboratory at the University of Nevada Reno has collocated multispectral photoacoustic instruments and reciprocal nephelometers to measure light absorption and light scattering coefficients as well as an AERONET operated CIMEL CE-318 ground-based sunphotometer. Preliminary measurements from August 2011 indicate substantially larger Cimel AOD than could be accounted for by use of the in situ aerosol extinction measurements combined with mixing height estimate. This poster presents new results comparing AERONET AOD and single scattering albedo and MODIS AOD with in situ measurements for summer and fall 2012, along with extensive back trajectory analysis, to evaluate conditions when satellite measurement may be useful for air pollution applications in Reno.

  13. The Core of the Stuttering Block

    ERIC Educational Resources Information Center

    Schwartz, Martin F.

    1974-01-01

    A model of the core of the stuttering block is presented, based on evidence that the disorder is essentially an inappropriate, vigorous contraction of the posterior cricoarytenoid in response to the subglottal air pressures required for speech. (Author)

  14. Geochemical constraints on Earth's core composition

    NASA Astrophysics Data System (ADS)

    Siebert, Julien

    2016-04-01

    The density of the core as measured from seismic-wave velocities is lower (by 10-15%) than that of pure iron, and therefore the core must also contain some light elements. Geophysical and cosmochemical constraints indicate that obvious candidates for these light elements include silicon, oxygen, and sulfur. These elements have been studied extensively for the past 30 years but a joint solution fulfilling all the requirements imposed by cosmochemistry and geochemistry, seismology, and models of Earth's accretion and core formation is still a highly controversial subject. Here are presented new experimental data in geochemistry used to place constraints on Earth's core composition. Metal-silicate partitioning experiments were performed at pressures and temperatures directly similar to those that prevailed in a deep magma ocean in the early Earth. The results show that core formation can reconcile the observed concentrations of siderophile elements in the silicate mantle with geophysical constraints on light elements in the core. Partitioning results also lead to a core containing less than 1 wt.% of sulfur, inconsistent with a S-rich layer to account for the observed structure of the outer core. Additionally, isotopic fractionations in core formation experiments are presented. This experimental tool merging the fields of experimental petrology and isotope geochemistry represents a promising approach, providing new independent constraints on the nature of light elements in the core.

  15. Enhanced waveguide-type ultraviolet electroluminescence from ZnO/MgZnO core/shell nanorod array light-emitting diodes via coupling with Ag nanoparticles localized surface plasmons.

    PubMed

    Zhang, Cen; Marvinney, Claire Elizabeth; Xu, Hai Yang; Liu, Wei Zhen; Wang, Chun Liang; Zhang, Li Xia; Wang, Jian Nong; Ma, Jian Gang; Liu, Yi Chun

    2015-01-21

    Localized surface plasmon (LSP) enhanced waveguide-type ultraviolet light-emitting diodes (LEDs) were fabricated by sputtering Ag nanoparticles (Ag-NPs) onto ZnO/MgZnO core/shell nanorod array (CS-NRA)/p-GaN heterostructures. A ∼9-fold enhancement of ZnO ultraviolet electroluminescence (EL) was demonstrated by the Ag-NPs decorated LED compared with the device without Ag-NPs. Angle-dependent EL measurements, as well as finite-difference time-domain simulations of the EL intensity spatial distribution, confirmed the waveguide-type EL transmission mode along the NR's axial direction. The increased spontaneous emission rate observed in time-resolved spectroscopy suggested that the ZnO EL enhancement was attributed to LSP-exciton/polariton coupling. However, a direct coupling is very difficult to achieve between Ag-LSPs and electron-hole pairs in the active region due to their "remote" separation. Thereby, two possible models involving the dynamic process of interactions among excitons, photons, and LSPs, were established to understand the selective enhancement of ZnO EL. PMID:25475883

  16. High quantum-yield CdSexS1-x/ZnS core/shell quantum dots for warm white light-emitting diodes with good color rendering

    NASA Astrophysics Data System (ADS)

    Duan, Hongyan; Jiang, Yang; Zhang, Yugang; Sun, Dapeng; Liu, Chao; Huang, Jian; Lan, Xinzheng; Zhou, Hongyang; Chen, Lei; Zhong, Honghai

    2013-07-01

    Composition-controllable ternary CdSexS1-x quantum dots (QDs) with multiple emission colors were obtained via a hot-injection-like method at a relatively low injection temperature (230 ° C) in octadecene. Then highly fluorescent CdSexS1-x/ZnS core/shell (CS) QDs were synthesized by a facile single-molecular precursor approach. The fluorescent quantum yield of the resulting green (λem = 523 nm), yellow (λem = 565 nm) and red (λem = 621 nm) emission of CS QDs in toluene reached up to 85%, 55% and 39%, respectively. Moreover, a QDs white light-emitting diode (QDs-WLED) was fabricated by hybridizing green-, yellow- and red-emitting CdSexS1-x/ZnS CS QDs/epoxy composites on a blue InGaN chip. The resulting four-band RYGB QDs-WLED showed good performance with CIE-1931 coordinates of (0.4137, 0.3955), an Ra of 81, and a Tc of 3360 K at 30 mA, which indicated the combination of multiple-color QDs with high fluorescence QYs in LEDs as a promising approach to obtain warm WLEDs with good color rendering.

  17. Light-induced changes in magnetism in a coordination polymer heterostructure, Rb0.24Co[Fe(CN)6]0.74@K0.10Co[Cr(CN)6]0.70·nH2O and the role of the shell thickness on the properties of both core and shell.

    PubMed

    Risset, Olivia N; Quintero, Pedro A; Brinzari, Tatiana V; Andrus, Matthew J; Lufaso, Michael W; Meisel, Mark W; Talham, Daniel R

    2014-11-01

    Particles of formula Rb0.24Co[Fe(CN)6]0.74@K0.10Co[Cr(CN)6]0.70·nH2O with a light-responsive rubidium cobalt hexacyanoferrate (RbCoFe) core and a magnetic potassium cobalt hexacyanochromate (KCoCr) shell have been prepared and exhibit light-induced changes in the magnetization of the normally light-insensitive KCoCr shell, a new property resulting from the synergy between the core and shell of a coordination polymer heterostructure. A single batch of 135 ± 12 nm RbCoFe particles are used as seeds to generate three different core@shell samples, with KCoCr shell thicknesses of approximately 11, 23 and 37 nm, to probe the influence of the shell thickness over the particles' morphology and structural and magnetic properties. Synchrotron powder X-ray diffraction reveals that structural changes in the shell accompany the charge transfer induced spin transition (CTIST) of the core, giving direct evidence that the photomagnetic response of the shell is magnetomechanical in origin. The depth to which the KCoCr shell contributes to changes in magnetization is estimated to be approximately 24 nm when using a model that assumes a constant magnetic response of the core within the series of particles. In turn, the presence of the shell changes the nature of the CTIST of the core. As opposed to the usually observed first order transition exhibiting hysteresis, the CTIST becomes continuous in the core@shell particles.

  18. Light-induced changes in magnetism in a coordination polymer heterostructure, Rb0.24Co[Fe(CN)6]0.74@K0.10Co[Cr(CN)6]0.70·nH2O and the role of the shell thickness on the properties of both core and shell.

    PubMed

    Risset, Olivia N; Quintero, Pedro A; Brinzari, Tatiana V; Andrus, Matthew J; Lufaso, Michael W; Meisel, Mark W; Talham, Daniel R

    2014-11-01

    Particles of formula Rb0.24Co[Fe(CN)6]0.74@K0.10Co[Cr(CN)6]0.70·nH2O with a light-responsive rubidium cobalt hexacyanoferrate (RbCoFe) core and a magnetic potassium cobalt hexacyanochromate (KCoCr) shell have been prepared and exhibit light-induced changes in the magnetization of the normally light-insensitive KCoCr shell, a new property resulting from the synergy between the core and shell of a coordination polymer heterostructure. A single batch of 135 ± 12 nm RbCoFe particles are used as seeds to generate three different core@shell samples, with KCoCr shell thicknesses of approximately 11, 23 and 37 nm, to probe the influence of the shell thickness over the particles' morphology and structural and magnetic properties. Synchrotron powder X-ray diffraction reveals that structural changes in the shell accompany the charge transfer induced spin transition (CTIST) of the core, giving direct evidence that the photomagnetic response of the shell is magnetomechanical in origin. The depth to which the KCoCr shell contributes to changes in magnetization is estimated to be approximately 24 nm when using a model that assumes a constant magnetic response of the core within the series of particles. In turn, the presence of the shell changes the nature of the CTIST of the core. As opposed to the usually observed first order transition exhibiting hysteresis, the CTIST becomes continuous in the core@shell particles. PMID:25286151

  19. Modal interferometer based on volatile organic compounds diffused in a simplified hollow-core photonic crystal fiber

    NASA Astrophysics Data System (ADS)

    Niu, Luo; Zhao, Chun-Liu; Kang, Juan; Ye, Man-Ping

    2013-12-01

    In this paper, a modal interferometer based on a simplified hollow-core PCF, which diffused with volatile organic compounds (VOCs) in the air holes, is proposed and investigated in our experiment. When light travels through the input single mode fiber and transmits into the simplified hollow-core PCF, there is only fundamental core mode. However, the high-order core modes will be excited when the molecules of VOCs diffuse into the air holes. After propagation of these modes in the simplified hollow-core PCF, they will recombine at the exit single mode fiber. The ethanol is chosen as the VOC sample in our experiments. The interference pattern of the interferometer, based on a 5.1 cm long simplified hollow-core PCF, exhibited fringe spacing of ~30 nm. The transmission intensity decreases while the fringe visibility increases as the ethanol concentration becomes larger, and the interference spectrum of the ethanol-diffused simplified hollow-core PCF modal interferometer has a red-shift, from 1542.96 nm at 250 ppm to 1545.52 nm at 1000 ppm. The modal interference proposed above has great potential as an optical fiber sensor, measuring physical parameters such as the concentration of VOCs.

  20. Energy spectrum and chemical composition of cosmic rays between 0.3 and 10 PeV determined from the cherenkov-light and charged-particle distributions in air showers

    NASA Astrophysics Data System (ADS)

    HEGRA-Collaboration; Arqueros, F.; Barrio, J. A.; Bernlöhr, K.; Bojahr, H.; Calle, I.; Contreras, J. L.; Cortina, J.; Deckers, T.; Denninghoff, S.; Fonseca, V.; Gebauer, J.; González, J. C.; Haustein, V.; Heinzelmann, G.; Hohl, H.; Horns, D.; Ibarra, A.; Kestel, M.; Kirstein, O.; Kornmayer, H.; Kranich, D.; Krawczynski, H.; Lindner, A.; Lorenz, E.; Magnussen, N.; Meyer, H.; Mirzoyan, R.; Moralejo, A.; Padilla, L.; Petry, D.; Plaga, R.; Prahl, J.; Rauterberg, G.; Rhode, W.; Röhring, A.; Samorski, M.; Schmele, D.; Schröder, F.; Stamm, W.; Wiebel-Sooth, B.; Willmer, M.; Wittek, W.

    2000-07-01

    Measurements of the lateral distribution of Cherenkov photons with the wide-angle atmospheric Cherenkov light detector array AIROBICC and of the charged particle lateral distribution with the scintillator matrix of the HEGRA air-shower detector complex in air showers are reported. They are used in conjunction to determine the energy spectrum and coarse chemical composition of charged cosmic rays in the energy interval from 0.3 PeV to 10 PeV. With the atmospheric shower-front sampling technique these detectors measure the electromagnetic component of an extensive air shower via the lateral density distribution of the shower particles and of the Cherenkov photons. The data are compared with events generated with the CORSIKA program package with the QGSJET hadronic-event generator. Consistency checks performed with primary energy-reconstruction methods based on different shower observables indicate satisfactory agreement between these extensive air shower simulations and the experimental data. This permits to derive results concerning the energy spectrum and composition of charged cosmic rays. The energy spectrum features a so called ``knee'' at an energy of E_knee=3.98+4.66-0.83 (stat) +/- 0.53 (syst) PeV. Power law fits to the differential energy spectrum yield indices of -2.72+0.02-0.03 (stat) +/- 0.07 (syst) below and -3.22+0.47-0.59 (stat) +/- 0.08 (syst) above the knee. The best-fit elongation rate for the whole energy range is determined to 78.3 +/- 1.0 (stat) +/- 6.2 (syst) g/cm2. At the highest energies it seems to decrease slightly. The best-fit fraction of light nuclei decreases from 37 +28-21% (combined statistical and systematic) to 8 +32-8% (combined statistical and systematic) \\ in the energy range discussed here. A detailed study of the systematic errors reveals that a non-changing composition cannot be excluded.

  1. Air cell

    NASA Astrophysics Data System (ADS)

    Okamura, Okiyoshi; Wakasa, Masayuki; Tamanoi, Yoshihito

    1991-04-01

    The present invention relates to an air cell. This air cell provides a compact light-weight power source for model aircraft permitting them to fly for an extended period so that they may be used for such practical purposes as crop dusting, surveying, and photographing. The cell is comprised of a current collector so disposed between a magnesium, zinc, or aluminum alloy cathode and a petroleum graphite anode that it is in contact with the anode. The anode is formed by adding polytetrafluoroethylene dispersion liquid in a mixture of active carbon and graphite powder, pouring the mixture into a mold and heating it to form the anode. It is fabricated by a plurality of anode sections and is formed with at least one hole so that it can provide a cell which is compact in size and light in weight yet is capable of generating a high output. The anode, the cathode, and a separator are wetted by an electrolytic liquid. The electrolyte is continuously supplied through the life of the cell.

  2. Visible-Light-Active Plasmonic Ag-SrTiO3 Nanocomposites for the Degradation of NO in Air with High Selectivity.

    PubMed

    Zhang, Qian; Huang, Yu; Xu, Lifeng; Cao, Jun-ji; Ho, Wingkei; Lee, Shun Cheng

    2016-02-17

    Harnessing inexhaustible solar energy for photocatalytic disposal of nitrogen oxides is of great significance nowadays. In this study, Ag-SrTiO3 nanocomposites (Ag-STO) were synthesized via one-pot solvothermal method for the first time. The deposition of Ag nanoparticles incurs a broad plasmonic resonance absorption in the visible light range, resulting in enhanced visible light driven activity on NO removal in comparison with pristine SrTiO3. The Ag loading amount has a significant influence on light absorption properties of Ag-STO, which further affects the photocatalytic efficiency. It was shown that 0.5% Ag loading onto SrTiO3 (in mass ratio) could remove 30% of NO in a single reaction path under visible light irradiation, which is twice higher than that achieved on pristine SrTiO3. Most importantly, the generation of harmful intermediate (NO2) is largely inhibited over SrTiO3 and Ag-STO nanocomposites, which can be ascribed to the basic surface property of strontium sites. As identified by electron spin resonance (ESR) spectra,·O2(-) and ·OH radicals are the major reactive species for NO oxidation. Essentially speaking, the abundance of reactive oxygen radicals produced over Ag-STO nanocomposites are responsible for the improved photocatalytic activity. This work provides a facile and controllable route to fabricate plasmonic Ag-SrTiO3 nanocomposite photocatalyst featuring high visible light activity and selectivity for NO abatement.

  3. Mercury's Core

    NASA Astrophysics Data System (ADS)

    Peale, S. J.

    2005-05-01

    In determining Mercury's core structure from its rotational properties, the location of Cassini state 1 is crucial. Convincing radar evidence indicates that the mantle rests on a liquid layer (Margot et al. 2005), but there are no empirical constraints on the moment of inertia C/MR2, which constraints must wait for the determination of the gravitational coefficients J2 and C22 from the MESSENGER orbiting spacecraft, and an accurate determination of the obliquity of the Cassini state. Tidal and core-mantle dissipation drive the spin to the Cassini state with a time scale O(105) years, so the spin should occupy the Cassini state and thereby define its obliquity---unless there has been a recent excitation of a free precession of the spin. Another way the spin might be displaced from the Cassini state is if the variations in the orbital elements, which change the position of the Cassini state, cause the spin axis to lag behind as it attempts to follow the state. Fortunately, the solid angle the spin axis encloses as it precesses around the Cassini state is an adiabatic invariant, and it is conserved if the orbital element variations are slow compared to the precession rate. As the precession period is O(1000) years, and the time scales of orbital parameter variations are O(105) years, the spin axis should remain very close to the Cassini state if it were ever close. But how close is close? The increasing precision of the radar and eventual spacecraft measurements warrants a check on the likely proximity of the spin axis to the Cassini state. By numerically following the positions of the spin axis and Cassini state with orbital parameters varying with time scales and amplitudes comparable to the real variations, we show that the spin should remain within 1″ of the Cassini state once dissipative torques bring it there. The current spin axis position should thus define the Cassini state sufficiently to put reasonably tight constraints on the core structure

  4. The Properties of Light

    NASA Astrophysics Data System (ADS)

    Haglund, Richard F.

    The mystery of light has formed the core of creation stories in every culture, and attracted the earnest attentions of philosophers since at least the fifth century BCE. Their questions have ranged from how and what we see, to the interaction of light with material bodies, and finally to the nature of light itself. This chapter begins with a brief intellectual history of light from ancient Greece to the end of the 19th century. After introducing the physical parameterization of light in terms of standard units, three concepts of light are introduced: light as a wave, light as a quantum particle, and light as a quantum field. After highlighting the distinctive characteristics of light beams from various sources - thermal radiation, luminescence from atoms and molecules, and synchrotron light sources - the distinctive physical characteristics of light beams are examined in some detail. The chapter concludes with a survey of the statistical and quantum-mechanical properties of light beams. In the appropriate limits, this treatment not only recovers the classical description of light waves and the semiclassical view of light as a stream of quanta, but also forms a consistent description of quantum phenomena - such as interference phenomena generated by single photons - that have no classical analogs.

  5. Air Pollution

    MedlinePlus

    Air pollution is a mixture of solid particles and gases in the air. Car emissions, chemicals from factories, ... Ozone, a gas, is a major part of air pollution in cities. When ozone forms air pollution, it's ...

  6. Optical fiber sensor having an active core

    NASA Technical Reports Server (NTRS)

    Egalon, Claudio Oliveira (Inventor); Rogowski, Robert S. (Inventor)

    1993-01-01

    An optical fiber is provided. The fiber is comprised of an active fiber core which produces waves of light upon excitation. A factor ka is identified and increased until a desired improvement in power efficiency is obtained. The variable a is the radius of the active fiber core and k is defined as 2 pi/lambda wherein lambda is the wavelength of the light produced by the active fiber core. In one embodiment, the factor ka is increased until the power efficiency stabilizes. In addition to a bare fiber core embodiment, a two-stage fluorescent fiber is provided wherein an active cladding surrounds a portion of the active fiber core having an improved ka factor. The power efficiency of the embodiment is further improved by increasing a difference between the respective indices of refraction of the active cladding and the active fiber core.

  7. Core refueling subsystem design description. Revision 1

    SciTech Connect

    Anderson, J.K.; Harvey, E.C.

    1987-07-01

    The Core Refueling Subsystem of the Fuel Handling and Storage System provides the mechanisms and tools necessary for the removal and replacement of the hexagonal elements which comprise the reactor core. The Core Refueling Subsystem is not "safety-related." The Core Refueling Subsystem equipment is used to prepare the plant for element removal and replacement, install the machines which handle the elements, maintain control of air inleakage and radiation release, transport the elements between the core and storage, and control the automatic and manual operations of the machines. Much of the element handling is performed inside the vessel, and the entire exchange of elements between storage and core is performed with the elements in a helium atmosphere. The core refueling operations are conducted with the reactor module shutdown and the primary coolant pressure slightly subatmospheric. The subsystem is capable of accomplishing the refueling in a reliable manner commensurate with the plant availability requirements.

  8. Bili lights

    MedlinePlus

    Phototherapy for jaundice; Bilirubin - bili lights; Neonatal care - bili lights; Newborn care - bili lights ... Phototherapy involves shining fluorescent light from the bili lights on bare skin. A specific wavelength of light can break down bilirubin into a form that ...

  9. Fate and aqueous transport of mercury in light of the Clean Air Mercury Rule for coal-fired electric power plants

    NASA Astrophysics Data System (ADS)

    Arzuman, Anry

    Mercury is a hazardous air pollutant emitted to the atmosphere in large amounts. Mercury emissions from electric power generation sources were estimated to be 48 metric tons/year, constituting the single largest anthropogenic source of mercury in the U.S. Settled mercury species are highly toxic contaminants of the environment. The newly issued Federal Clean Air Mercury Rule requires that the electric power plants firing coal meet the new Maximum Achievable Mercury Control Technology limit by 2018. This signifies that all of the air-phase mercury will be concentrated in solid phase which, based on the current state of the Air Pollution Control Technology, will be fly ash. Fly ash is utilized by different industries including construction industry in concrete, its products, road bases, structural fills, monifills, for solidification, stabilization, etc. Since the increase in coal combustion in the U.S. (1.6 percent/year) is much higher than the fly ash demand, large amounts of fly ash containing mercury and other trace elements are expected to accumulate in the next decades. The amount of mercury transferred from one phase to another is not a linear function of coal combustion or ash production, depends on the future states of technology, and is unknown. The amount of aqueous mercury as a function of the future removal, mercury speciation, and coal and aquifer characteristics is also unknown. This paper makes a first attempt to relate mercury concentrations in coal, flue gas, fly ash, and fly ash leachate using a single algorithm. Mercury concentrations in all phases were examined and phase transformation algorithms were derived in a form suitable for probabilistic analyses. Such important parameters used in the transformation algorithms as Soil Cation Exchange Capacity for mercury, soil mercury selectivity sequence, mercury activity coefficient, mercury retardation factor, mercury species soil adsorption ratio, and mercury Freundlich soil adsorption isotherm

  10. AIR COOLED NEUTRONIC REACTOR

    DOEpatents

    Fermi, E.; Szilard, L.

    1958-05-27

    A nuclear reactor of the air-cooled, graphite moderated type is described. The active core consists of a cubicle mass of graphite, approximately 25 feet in each dimension, having horizontal channels of square cross section extending between two of the opposite faces, a plurality of cylindrical uranium slugs disposed in end to end abutting relationship within said channels providing a space in the channels through which air may be circulated, and a cadmium control rod extending within a channel provided in the moderator. Suitable shielding is provlded around the core, as are also provided a fuel element loading and discharge means, and a means to circulate air through the coolant channels through the fuel charels to cool the reactor.

  11. Mechanical properties of protein adsorption layers at the air/water and oil/water interface: a comparison in light of the thermodynamical stability of proteins.

    PubMed

    Mitropoulos, Varvara; Mütze, Annekathrin; Fischer, Peter

    2014-04-01

    Over the last decades numerous studies on the interfacial rheological response of protein adsorption layers have been published. The comparison of these studies and the retrieval of a common parameter to compare protein interfacial activity are hampered by the fact that different boundary conditions (e.g. physico-chemical, instrumental, interfacial) were used. In the present work we review previous studies and attempt a unifying approach for the comparison between bulk protein properties and their adsorption films. Among many common food grade proteins we chose bovine serum albumin, β-lactoglobulin and lysozyme for their difference in thermodynamic stability and studied their adsorption at the air/water and limonene/water interface. In order to achieve this we have i) systematically analyzed protein adsorption kinetics in terms of surface pressure rise using a drop profile analysis tensiometer and ii) we addressed the interfacial layer properties under shear stress using an interfacial shear rheometer under the same experimental conditions. We could show that thermodynamically less stable proteins adsorb generally faster and yield films with higher shear rheological properties at air/water interface. The same proteins showed an analog behavior when adsorbing at the limonene/water interface but at slower rates. PMID:24332621

  12. Mechanical properties of protein adsorption layers at the air/water and oil/water interface: a comparison in light of the thermodynamical stability of proteins.

    PubMed

    Mitropoulos, Varvara; Mütze, Annekathrin; Fischer, Peter

    2014-04-01

    Over the last decades numerous studies on the interfacial rheological response of protein adsorption layers have been published. The comparison of these studies and the retrieval of a common parameter to compare protein interfacial activity are hampered by the fact that different boundary conditions (e.g. physico-chemical, instrumental, interfacial) were used. In the present work we review previous studies and attempt a unifying approach for the comparison between bulk protein properties and their adsorption films. Among many common food grade proteins we chose bovine serum albumin, β-lactoglobulin and lysozyme for their difference in thermodynamic stability and studied their adsorption at the air/water and limonene/water interface. In order to achieve this we have i) systematically analyzed protein adsorption kinetics in terms of surface pressure rise using a drop profile analysis tensiometer and ii) we addressed the interfacial layer properties under shear stress using an interfacial shear rheometer under the same experimental conditions. We could show that thermodynamically less stable proteins adsorb generally faster and yield films with higher shear rheological properties at air/water interface. The same proteins showed an analog behavior when adsorbing at the limonene/water interface but at slower rates.

  13. Relation between gamma-ray family and EAS core: Monte-Carlo simulation of EAS core

    NASA Technical Reports Server (NTRS)

    Yanagita, T.

    1985-01-01

    Preliminary results of Monte-Carlo simulation on Extensive Air Showers (EAS) (Ne=100,000) core is reported. For the first collision at the top of the atmosphere, high multiplicity (high rapidity, density) and a large Pt (1.5GeV average) model is assumed. Most of the simulated cores show a complicated structure.

  14. Polymer-gas reactions (air pollutants: NO2 and SO2) as function of pressure, UV light, temperature, and morphology: A survey

    NASA Technical Reports Server (NTRS)

    Jellinek, H. H. G.

    1972-01-01

    Reactions of various polymers, such as polystyrene and its stereo-specific isomers, butylrubber, nylon, etc., with nitrogen dioxide and sulfur-dioxide were studied over the past few years. More recently, work has been initiated on the influence of polymer morphology on degradation of polymers in presence of these gases, near UV radiation and oxygen. Unexpected effects have been observed during chain scission near room temperature. Thus, for instance, isotactic polystyrene of various crystallinities, as far as extent and type are concerned, show marked differences in their degradation characteristics. Thus, for instance, crystalline polymers show faster degradation than amorphous ones, which seems to be contrary to expectations. However, this phenomenon can be explained in quite a consistent manner. The importance of all these reactions in connection with air pollution is briefly discussed.

  15. Improved electron injection and transport by use of baking soda as a low-cost, air-stable, n-dopant for solution-processed phosphorescent organic light-emitting diodes

    NASA Astrophysics Data System (ADS)

    Earmme, Taeshik; Jenekhe, Samson A.

    2013-06-01

    Sodium bicarbonate (baking soda, NaHCO3) is found to be an efficient low-cost, air-stable, and environmentally friendly n-dopant for electron-transport layer (ETL) in solution-processed phosphorescent organic light-emitting diodes (PhOLEDs). A 2.0-fold enhancement in power efficiency of blue PhOLEDs is observed by use of NaHCO3-doped 4,7-diphenyl-1,10-phenanthroline (BPhen) ETL. The bulk conductivity of NaHCO3-doped BPhen film is increased by 5 orders of magnitude. Enhanced performance of PhOLEDs is similarly observed by use of NaHCO3-doped 1,3,5-tris(m-pyrid-3-yl-phenyl)benzene ETL. These results demonstrate that sodium bicarbonate is an effective n-dopant in organic electronics.

  16. Inner Core Structure Behind the PKP Core Phase Triplication

    NASA Astrophysics Data System (ADS)

    Blom, N.; Paulssen, H.; Deuss, A. F.; Waszek, L.

    2015-12-01

    Despite its small size, the Earth's inner core plays an important role in the Earth's dynamics. Because it is slowly growing, its structure - and the variation thereof with depth - may reveal important clues about the history of the core, its convection and the resulting geodynamo. Learning more about this structure has been a prime effort in the past decades, leading to discoveries about anisotropy, hemispheres and heterogeneity in the inner core in general. In terms of detailed structure, mainly seismic body waves have contributed to these advances. However, at depths between ~100-200 km, the seismic structure is relatively poorly known. This is a result of the PKP core phase triplication and the existence of strong precursors to PKP phases, whose simultaneous arrival hinders the measurement of inner core waves PKIKP at epicentral distances between roughly 143-148°. As a consequence, the interpretation of deeper structure also remains difficult. To overcome these issues, we stack seismograms in slowness and time, separating PKP and PKIKP phases which arrive simultaneously, but with different slowness. We apply this method to study the inner core's Western hemisphere between South and Central America using paths travelling in the quasi-polar direction between epicentral distances of 140-150°. This enables us to measure PKiKP-PKIKP differential travel times up to greater epicentral distance than has previously been done. The resulting differential travel time residuals increase with epicentral distance, indicating a marked increase in seismic velocity with depth compared to reference model AK135 for the studied polar paths. Assuming a homogeneous outer core, these findings can be explained by either (i) inner core heterogeneity due to an increase in isotropic velocity, or (ii) increase in anisotropy over the studied depth range. Our current data set cannot distinguish between the two hypotheses, but in light of previous work we prefer the latter interpretation.

  17. Fiber optic direct Raman imaging system based on a hollow-core fiber bundle

    NASA Astrophysics Data System (ADS)

    Inoue, S.; Katagiri, T.; Matsuura, Y.

    2015-03-01

    A Raman imaging system which combined a hollow fiber bundle and a direct imaging technique was constructed for high-speed endoscopic Raman imaging. The hollow fiber bundle is fabricated by depositing a silver thin film on the inner surface of pre-drawn glass capillary bundle. It performs as a fiber optic probe which transmits a Raman image with high signal-to-noise ratio because the propagating light is confined into the air core inducing little light scattering. The field of view on the sample is uniformly irradiated by the excitation laser light via the probe. The back-scattered image is collected by the probe and captured directly by an image sensor. A pair of thin film tunable filters is used to select target Raman band. This imaging system enables flexible and high-speed Raman imaging of biological tissues.

  18. HIGH-FREQUENCY-PEAKED BL LACERTAE OBJECTS AS SPECTRAL CANDLES TO MEASURE THE EXTRAGALACTIC BACKGROUND LIGHT IN THE FERMI AND AIR CHERENKOV TELESCOPES ERA

    SciTech Connect

    Mankuzhiyil, Nijil; Persic, Massimo; Tavecchio, Fabrizio

    2010-05-20

    The extragalactic background light (EBL) is the integrated light from all the stars that have ever formed, and spans the IR-UV range. The interaction of very high-energy (VHE: E > 100 GeV) {gamma}-rays, emitted by sources located at cosmological distances, with the intervening EBL results in e {sup -} e {sup +} pair production that leads to energy-dependent attenuation of the observed VHE flux. This introduces a fundamental ambiguity into the interpretation of measured VHE {gamma}-ray spectra: neither the intrinsic spectrum nor the EBL are separately known-only their combination is. In this Letter, we propose a method to measure the EBL photon number density. It relies on using simultaneous observations of BL Lac objects in the optical, X-ray, high-energy (HE: E > 100 MeV) {gamma}-ray (from the Fermi telescope), and VHE {gamma}-ray (from Cherenkov telescopes) bands. For each source, the method involves best-fitting the spectral energy distribution from optical through HE {gamma}-rays (the latter being largely unaffected by EBL attenuation as long as z {approx_lt} 1) with a synchrotron self-Compton model. We extrapolate such best-fitting models into the VHE regime and assume they represent the BL Lacs' intrinsic emission. Contrasting measured versus intrinsic emission leads to a determination of the {gamma}{gamma} opacity to VHE photons. Using, for each given source, different states of emission will only improve the accuracy of the proposed method. We demonstrate this method using recent simultaneous multifrequency observations of the high-frequency-peaked BL Lac object PKS 2155-304 and discuss how similar observations can more accurately probe the EBL.

  19. Nonlinear compression of ultrafast industrial lasers in hypocyloid-core Kagome hollow-core fiber

    NASA Astrophysics Data System (ADS)

    Giree, A.; Guichard, F.; Machinet, G.; Zaouter, Y.; Hagen, Y.; Debords, B.; Dupriez, P.; Gérôme, F.; Hanna, M.; Benabid, F.; Hönninger, C.; Georges, P.; Mottay, E.

    2015-03-01

    The duration of energetic ultrashort pulses is usually limited by the available gain bandwidth of ultrashort amplifiers used to amplify nJ or pJ level seed to hundreds of μμJ or even several mJ. In the case of Ytterbium-doped fiber amplifiers, the available bandwidth is of the order of 40 nm, typically limiting the pulse duration of high-energy fiber chirped-pulse amplifiers to durations above 300 fs. In the case of solid-state amplifier based on Yb:YAG crystals, the host matrix order restricts the amplification bandwidth even more leading to pulses in the low picosecond range. Both architecture would greatly benefit from pulse durations well-below what is allowed by their respective gain bandwidth e.g. sub-100 fs for fiber amplifier and sub-300 fs for solid-state Yb:YAG amplifier. In this contribution, we report on the post-compression of two high energy industrial ultrashort fiber and thin-disk amplifiers using an innovative and efficient hollow core fiber structure, namely the hypocycloid-core Kagome fiber. This fiber exhibits remarkably low propagation losses due to the unique inhibited guidance mechanism that minimize that amount of light propagating in the silica cladding surrounding the hollow core. Spectral broadening is realized in a short piece of Kagome fiber filled with air at 1 atmosphere pressure. For both amplifiers, we were able to demonstrate more than 200 μJ of energy per pulse with duration <100 fs in the case of the fiber amplifier and <300 fs in the case of the thin disk amplifier. Limitations and further energy scaling will also be discussed.

  20. Air Abrasion

    MedlinePlus

    ... delivered directly to your desktop! more... What Is Air Abrasion? Article Chapters What Is Air Abrasion? What Happens? The Pros and Cons Will I Feel Anything? Is Air Abrasion for Everyone? print full article print this ...

  1. Light weight aluminum optics

    NASA Astrophysics Data System (ADS)

    Catura, R. C.; Vieira, J. R.

    1985-09-01

    Light weight mirror blanks were fabricated by dip-brazing a core of low mass aluminum foam material to thin face sheets of solid aluminum. The blanks weigh 40% of an equivalent size solid mirror and were diamond turned to provide reflective surfaces. Optical interferometry was used to assess their dimensional stability over 7 months. No changes in flatness are observed (to the sensitivity of the measurements of a half wavelength of red light).

  2. Lighting: Green Light.

    ERIC Educational Resources Information Center

    Maniccia, Dorine

    2003-01-01

    Explains that by using sustainable (green) building practices, schools and universities can make their lighting systems more efficient, noting that embracing green design principles can help schools attract students. Discusses lighting-control technologies (occupancy sensing technology, daylighting technology, and scheduling based technologies),…

  3. Simplified hollow-core photonic crystal fiber.

    PubMed

    Gérôme, Frédéric; Jamier, Raphaël; Auguste, Jean-Louis; Humbert, Georges; Blondy, Jean-Marc

    2010-04-15

    An original design of hollow-core photonic crystal fiber composed of a thin silica ring suspended in air by six silica struts is proposed. This structure can be viewed as a simplified Kagomé-lattice fiber reduced to one layer of air holes. By working on the core surround parameters, an efficient antiresonant air guiding was successfully demonstrated. Two large low-loss windows (visible/IR) were measured with a minimum attenuation less than 0.2 dB radicalm at yellow wavelengths, comparable with state-of-the-art designs. The curvature behavior was also studied, showing low bending loss sensitivity for the fundamental transmission band. These relevant features might open a new route to propose original hollow-core fiber designs while making their production simpler and faster than previously.

  4. Baseline Design Compliance Matrix for the Rotary Mode Core Sampling System

    SciTech Connect

    LECHELT, J.A.

    2000-10-17

    The purpose of the design compliance matrix (DCM) is to provide a single-source document of all design requirements associated with the fifteen subsystems that make up the rotary mode core sampling (RMCS) system. It is intended to be the baseline requirement document for the RMCS system and to be used in governing all future design and design verification activities associated with it. This document is the DCM for the RMCS system used on Hanford single-shell radioactive waste storage tanks. This includes the Exhauster System, Rotary Mode Core Sample Trucks, Universal Sampling System, Diesel Generator System, Distribution Trailer, X-Ray Cart System, Breathing Air Compressor, Nitrogen Supply Trailer, Casks and Cask Truck, Service Trailer, Core Sampling Riser Equipment, Core Sampling Support Trucks, Foot Clamp, Ramps and Platforms and Purged Camera System. Excluded items are tools such as light plants and light stands. Other items such as the breather inlet filter are covered by a different design baseline. In this case, the inlet breather filter is covered by the Tank Farms Design Compliance Matrix.

  5. Method and device for optimizing the air-fuel mixture burn rate of internal combustion engines during low speed, light and heavy load operating conditions

    SciTech Connect

    Burandt, C.O.

    1990-10-09

    This patent describes a method for optimizing low speed light load and low speed heavy load operating conditions in an internal combustion engine. The engine has a camshaft, a crankshaft, at least one intake valve and at least one piston, and is capable of providing for small valve events, and the engine providing for earlier than normal intake valve closings the method comprises: sensing the load demand on the engine, regulating the phasing of the operation of the camshaft of the engine with the operation of the crankshaft of the engine in response to the sensed load demand by advancing the operation of camshaft relative to the operation of the crankshaft when a heavy load demand is sensed and by retarding the operation of the camshaft relative to the operation of the crankshaft when alight load demand is sensed, and sensing detonation in the engine and regulating the phasing operation of the camshaft relative to the operation of the crankshaft by advancing the operation of the camshaft relative to the crankshaft when detonation is sensed.

  6. Nanoparticle filtration performance of NIOSH-certified particulate air-purifying filtering facepiece respirators: evaluation by light scattering photometric and particle number-based test methods.

    PubMed

    Rengasamy, Samy; Eimer, Benjamin C

    2012-01-01

    National Institute for Occupational Safety and Health (NIOSH) certification test methods employ charge neutralized NaCl or dioctyl phthalate (DOP) aerosols to measure filter penetration levels of air-purifying particulate respirators photometrically using a TSI 8130 automated filter tester at 85 L/min. A previous study in our laboratory found that widely different filter penetration levels were measured for nanoparticles depending on whether a particle number (count)-based detector or a photometric detector was used. The purpose of this study was to better understand the influence of key test parameters, including filter media type, challenge aerosol size range, and detector system. Initial penetration levels for 17 models of NIOSH-approved N-, R-, and P-series filtering facepiece respirators were measured using the TSI 8130 photometric method and compared with the particle number-based penetration (obtained using two ultrafine condensation particle counters) for the same challenge aerosols generated by the TSI 8130. In general, the penetration obtained by the photometric method was less than the penetration obtained with the number-based method. Filter penetration was also measured for ambient room aerosols. Penetration measured by the TSI 8130 photometric method was lower than the number-based ambient aerosol penetration values. Number-based monodisperse NaCl aerosol penetration measurements showed that the most penetrating particle size was in the 50 nm range for all respirator models tested, with the exception of one model at ~200 nm size. Respirator models containing electrostatic filter media also showed lower penetration values with the TSI 8130 photometric method than the number-based penetration obtained for the most penetrating monodisperse particles. Results suggest that to provide a more challenging respirator filter test method than what is currently used for respirators containing electrostatic media, the test method should utilize a sufficient number

  7. Nanoparticle filtration performance of NIOSH-certified particulate air-purifying filtering facepiece respirators: evaluation by light scattering photometric and particle number-based test methods.

    PubMed

    Rengasamy, Samy; Eimer, Benjamin C

    2012-01-01

    National Institute for Occupational Safety and Health (NIOSH) certification test methods employ charge neutralized NaCl or dioctyl phthalate (DOP) aerosols to measure filter penetration levels of air-purifying particulate respirators photometrically using a TSI 8130 automated filter tester at 85 L/min. A previous study in our laboratory found that widely different filter penetration levels were measured for nanoparticles depending on whether a particle number (count)-based detector or a photometric detector was used. The purpose of this study was to better understand the influence of key test parameters, including filter media type, challenge aerosol size range, and detector system. Initial penetration levels for 17 models of NIOSH-approved N-, R-, and P-series filtering facepiece respirators were measured using the TSI 8130 photometric method and compared with the particle number-based penetration (obtained using two ultrafine condensation particle counters) for the same challenge aerosols generated by the TSI 8130. In general, the penetration obtained by the photometric method was less than the penetration obtained with the number-based method. Filter penetration was also measured for ambient room aerosols. Penetration measured by the TSI 8130 photometric method was lower than the number-based ambient aerosol penetration values. Number-based monodisperse NaCl aerosol penetration measurements showed that the most penetrating particle size was in the 50 nm range for all respirator models tested, with the exception of one model at ~200 nm size. Respirator models containing electrostatic filter media also showed lower penetration values with the TSI 8130 photometric method than the number-based penetration obtained for the most penetrating monodisperse particles. Results suggest that to provide a more challenging respirator filter test method than what is currently used for respirators containing electrostatic media, the test method should utilize a sufficient number

  8. Light shield and cooling apparatus. [high intensity ultraviolet lamp

    NASA Technical Reports Server (NTRS)

    Meador, T. G., Jr. (Inventor)

    1974-01-01

    A light shield and cooling apparatus was developed for a high intensity ultraviolet lamp including water and high pressure air for cooling and additional apparatus for shielding the light and suppressing the high pressure air noise.

  9. Photothermal desorption of single-walled carbon nanotubes and coconut shell-activated carbons using a continuous light source for application in air sampling.

    PubMed

    Floyd, Evan L; Sapag, Karim; Oh, Jonghwa; Lungu, Claudiu T

    2014-08-01

    Many techniques exist to measure airborne volatile organic compounds (VOCs), each with differing advantages; sorbent sampling is compact, versatile, has good sample stability, and is the preferred technique for collecting VOCs for hygienists. Development of a desorption technique that allows multiple analyses per sample (similar to chemical desorption) with enhanced sensitivity (similar to thermal desorption) would be helpful to field hygienists. In this study, activated carbon (AC) and single-walled carbon nanotubes (SWNT) were preloaded with toluene vapor and partially desorbed with light using a common 12-V DC, 50-W incandescent/halogen lamp. A series of experimental chamber configurations were explored starting with a 500-ml chamber under static conditions, then with low ventilation and high ventilation, finally a 75-ml high ventilation chamber was evaluated. When preloaded with toluene and irradiated at the highest lamp setting for 4min, AC desorbed 13.9, 18.5, 23.8, and 45.9% of the loaded VOC mass, in each chamber configuration, respectively; SWNT desorbed 25.2, 24.3, 37.4, and 70.5% of the loaded VOC mass, respectively. SWNT desorption was significantly greater than AC in all test conditions (P = 0.02-<0.0001) demonstrating a substantial difference in sorbent performance. When loaded with 0.435mg toluene and desorbed at the highest lamp setting for 4min in the final chamber design, the mean desorption for AC was 45.8% (39.7, 52.0) and SWNT was 72.6% (68.8, 76.4) (mean represented in terms of 95% confidence interval). All desorption measurements were obtained using a field grade photoionization detector; this demonstrates the potential of using this technique to perform infield prescreening of VOC samples for immediate exposure feedback and in the analytical lab to introduce sample to a gas chromatograph for detailed analysis of the sample.

  10. Photothermal Desorption of Single-Walled Carbon Nanotubes and Coconut Shell-Activated Carbons Using a Continuous Light Source for Application in Air Sampling

    PubMed Central

    Floyd, Evan L.; Sapag, Karim; Oh, Jonghwa; Lungu, Claudiu T.

    2014-01-01

    Many techniques exist to measure airborne volatile organic compounds (VOCs), each with differing advantages; sorbent sampling is compact, versatile, has good sample stability, and is the preferred technique for collecting VOCs for hygienists. Development of a desorption technique that allows multiple analyses per sample (similar to chemical desorption) with enhanced sensitivity (similar to thermal desorption) would be helpful to field hygienists. In this study, activated carbon (AC) and single-walled carbon nanotubes (SWNT) were preloaded with toluene vapor and partially desorbed with light using a common 12-V DC, 50-W incandescent/halogen lamp. A series of experimental chamber configurations were explored starting with a 500-ml chamber under static conditions, then with low ventilation and high ventilation, finally a 75-ml high ventilation chamber was evaluated. When preloaded with toluene and irradiated at the highest lamp setting for 4min, AC desorbed 13.9, 18.5, 23.8, and 45.9% of the loaded VOC mass, in each chamber configuration, respectively; SWNT desorbed 25.2, 24.3, 37.4, and 70.5% of the loaded VOC mass, respectively. SWNT desorption was significantly greater than AC in all test conditions (P = 0.02–<0.0001) demonstrating a substantial difference in sorbent performance. When loaded with 0.435mg toluene and desorbed at the highest lamp setting for 4min in the final chamber design, the mean desorption for AC was 45.8% (39.7, 52.0) and SWNT was 72.6% (68.8, 76.4) (mean represented in terms of 95% confidence interval). All desorption measurements were obtained using a field grade photoionization detector; this demonstrates the potential of using this technique to perform infield prescreening of VOC samples for immediate exposure feedback and in the analytical lab to introduce sample to a gas chromatograph for detailed analysis of the sample. PMID:25016598

  11. Illuminating system and method for specialized and decorative lighting using liquid light guides

    DOEpatents

    Zorn, Carl J.; Kross, Brian J.; Majewski, Stanislaw; Wojcik, Randolph F.

    1998-01-01

    The present invention comprises an illumination system for specialized decorative lighting including a light source, a flexible plastic tube sheath for distributing the light to a remote location, a transparent liquid core filling the tube that has an index of refraction greater than that of the plastic tube and an arrangement where light coupled from the light source is caused to leak from the liquid light guide at desired locations for the purposes of specialized lighting, such as underwater illumination in swimming pools.

  12. A simple way to establish a dual-core hollow fiber for laser surgery applications

    NASA Astrophysics Data System (ADS)

    Jing, Chengbin; Kendall, Wesley; Harrington, James A.

    2016-03-01

    A dual-core hollow fiber has two separate cores for propagation of light. Such a fiber can have some good applications in laser surgery. The dual-core guide can transmit an infrared laser beam for cutting or ablation while a visible laser beam is simultaneously transmitted as a pilot or aiming beam. The traditional fabrication procedure for a dual-core hollow fiber involves chemical vapor deposition (CVD) growth on silica tubing of an inner cladding layer followed by the deposition of a low index polymer on the outside of the tubing. This will provide a hollow structure that has a clad-core-clad tube. This work provides an alternative approach which involves nesting of two hollow waveguides to establish a dual-core hollow fiber. An Ag/AgI hollow glass fiber is fabricated for transmitting CO2 laser. Another silica glass tube is selected carefully so that its inner diameter is just slightly larger than the outer diameter of the Ag/AgI hollow fiber. The outer surface of the as-selected glass tubing is coated with a low refractive index polymer. The Ag/AgI hollow fiber was inserted into the polymer coated silica glass tubing to establish an air or silicone oil gap between the two tubes. A visible laser beam is transmitted through the outer tube's core. The CO2 laser beam is transmitted through the inner Ag/AgI hollow fiber. The dual-core hollow fibers show good transmission for both the red aiming beam and the CO2 laser. Therefore this structure can be a good candidate for laser surgery applications.

  13. Core-core and core-valence correlation

    NASA Technical Reports Server (NTRS)

    Bauschlicher, Charles W., Jr.; Langhoff, Stephen R.; Taylor, Peter R.

    1988-01-01

    The effect of (1s) core correlation on properties and energy separations was analyzed using full configuration-interaction (FCI) calculations. The Be 1 S - 1 P, the C 3 P - 5 S and CH+ 1 Sigma + or - 1 Pi separations, and CH+ spectroscopic constants, dipole moment and 1 Sigma + - 1 Pi transition dipole moment were studied. The results of the FCI calculations are compared to those obtained using approximate methods. In addition, the generation of atomic natural orbital (ANO) basis sets, as a method for contracting a primitive basis set for both valence and core correlation, is discussed. When both core-core and core-valence correlation are included in the calculation, no suitable truncated CI approach consistently reproduces the FCI, and contraction of the basis set is very difficult. If the (nearly constant) core-core correlation is eliminated, and only the core-valence correlation is included, CASSCF/MRCI approached reproduce the FCI results and basis set contraction is significantly easier.

  14. Mercury's thermal evolution and core crystallization regime

    NASA Astrophysics Data System (ADS)

    Rivoldini, A.; Van Hoolst, T.; Dumberry, M.; Steinle-Neumann, G.

    2015-10-01

    Unlike the Earth, where the liquid core isentrope is shallower than the core liquidus, at the lower pressures inside Mercury's core the isentrope can be steeper than the melting temperature. As a consequence, upon cooling, the isentrope may first enter a solid stability field near the core mantle boundary and produce ironrich snow that sinks under gravity and produces buoyant upwellings of iron depleted fluid. Similar to bottom up crystallization, crystallization initiated near the top might generate sufficient buoyancy flux to drive magnetic field generation by compositional convection.In this study we model Mercury's thermal evolution by taking into account the formation of iron-rich snow to assess when the conditions for an internally magnetic field can be satisfied. We employ a thermodynamic consistent description of the iron high-pressure phase diagram and thermoelastic properties of iron alloys as well as the most recent data about the thermal conductivity of core materials. We use a 1-dimensional parametrized thermal evolution model in the stagnant lid regime for the mantle (e.g. [1]) that is coupled to the core. The model for the mantle takes into account the formation of the crust due to melting at depth. Mantle convection is driven by heat producing radioactive elements, heat loss from secular cooling and from the heat supplied by the core. The heat generated inside the core is mainly provided from secular cooling, from the latent heat released at iron freezing, and from gravitational energy resulting form the release of light elements at the inner core-outer core boundary as well as from the sinking of iron-rich snow and subsequent upwellings of light elements in the snow zone. If the heat flow out of the core is smaller than the heat transported along the core isentrope a thermal boundary will from at the top of the outer core. To determine the extension of the convecting region inside the liquid core we calculate the convective power [2]. Finally, we

  15. Core formation and core composition from coupled geochemical and geophysical constraints.

    PubMed

    Badro, James; Brodholt, John P; Piet, Hélène; Siebert, Julien; Ryerson, Frederick J

    2015-10-01

    The formation of Earth's core left behind geophysical and geochemical signatures in both the core and mantle that remain to this day. Seismology requires that the core be lighter than pure iron and therefore must contain light elements, and the geochemistry of mantle-derived rocks reveals extensive siderophile element depletion and fractionation. Both features are inherited from metal-silicate differentiation in primitive Earth and depend upon the nature of physiochemical conditions that prevailed during core formation. To date, core formation models have only attempted to address the evolution of core and mantle compositional signatures separately, rather than seeking a joint solution. Here we combine experimental petrology, geochemistry, mineral physics and seismology to constrain a range of core formation conditions that satisfy both constraints. We find that core formation occurred in a hot (liquidus) yet moderately deep magma ocean not exceeding 1,800 km depth, under redox conditions more oxidized than present-day Earth. This new scenario, at odds with the current belief that core formation occurred under reducing conditions, proposes that Earth's magma ocean started oxidized and has become reduced through time, by oxygen incorporation into the core. This core formation model produces a core that contains 2.7-5% oxygen along with 2-3.6% silicon, with densities and velocities in accord with radial seismic models, and leaves behind a silicate mantle that matches the observed mantle abundances of nickel, cobalt, chromium, and vanadium. PMID:26392555

  16. Core formation and core composition from coupled geochemical and geophysical constraints.

    PubMed

    Badro, James; Brodholt, John P; Piet, Hélène; Siebert, Julien; Ryerson, Frederick J

    2015-10-01

    The formation of Earth's core left behind geophysical and geochemical signatures in both the core and mantle that remain to this day. Seismology requires that the core be lighter than pure iron and therefore must contain light elements, and the geochemistry of mantle-derived rocks reveals extensive siderophile element depletion and fractionation. Both features are inherited from metal-silicate differentiation in primitive Earth and depend upon the nature of physiochemical conditions that prevailed during core formation. To date, core formation models have only attempted to address the evolution of core and mantle compositional signatures separately, rather than seeking a joint solution. Here we combine experimental petrology, geochemistry, mineral physics and seismology to constrain a range of core formation conditions that satisfy both constraints. We find that core formation occurred in a hot (liquidus) yet moderately deep magma ocean not exceeding 1,800 km depth, under redox conditions more oxidized than present-day Earth. This new scenario, at odds with the current belief that core formation occurred under reducing conditions, proposes that Earth's magma ocean started oxidized and has become reduced through time, by oxygen incorporation into the core. This core formation model produces a core that contains 2.7-5% oxygen along with 2-3.6% silicon, with densities and velocities in accord with radial seismic models, and leaves behind a silicate mantle that matches the observed mantle abundances of nickel, cobalt, chromium, and vanadium.

  17. Core formation and core composition from coupled geochemical and geophysical constraints

    PubMed Central

    Badro, James; Brodholt, John P.; Piet, Hélène; Siebert, Julien; Ryerson, Frederick J.

    2015-01-01

    The formation of Earth’s core left behind geophysical and geochemical signatures in both the core and mantle that remain to this day. Seismology requires that the core be lighter than pure iron and therefore must contain light elements, and the geochemistry of mantle-derived rocks reveals extensive siderophile element depletion and fractionation. Both features are inherited from metal−silicate differentiation in primitive Earth and depend upon the nature of physiochemical conditions that prevailed during core formation. To date, core formation models have only attempted to address the evolution of core and mantle compositional signatures separately, rather than seeking a joint solution. Here we combine experimental petrology, geochemistry, mineral physics and seismology to constrain a range of core formation conditions that satisfy both constraints. We find that core formation occurred in a hot (liquidus) yet moderately deep magma ocean not exceeding 1,800 km depth, under redox conditions more oxidized than present-day Earth. This new scenario, at odds with the current belief that core formation occurred under reducing conditions, proposes that Earth’s magma ocean started oxidized and has become reduced through time, by oxygen incorporation into the core. This core formation model produces a core that contains 2.7–5% oxygen along with 2–3.6% silicon, with densities and velocities in accord with radial seismic models, and leaves behind a silicate mantle that matches the observed mantle abundances of nickel, cobalt, chromium, and vanadium. PMID:26392555

  18. Cadmium Telluride, Cadmium Telluride/Cadmium Sulfide Core/Shell, and Cadmium Telluride/Cadmium Sulfide/Zinc Sulfide Core/Shell/Shell Quantum Dots Study

    NASA Astrophysics Data System (ADS)

    Yan, Yueran

    CdTe, CdTe/CdS core/shell, and CdTe/CdS/ZnS core/shell/shell quantum dots (QDs) are potential candidates for bio-imaging and solar cell applications because of some special physical properties in these nano materials. For example, the band gap energy of the bulk CdTe is about 1.5 eV, so that principally they can emit 790 nm light, which is in the near-infrared range (also called biological window). Moreover, theoretically hot exciton generated by QDs is possible to be caught since the exciton relaxation process in QDs is slower than in bulk materials due to the large intraband energy gap in QDs. In this dissertation, we have synthesized the CdTe and CdTe/CdS core/shell QDs, characterized their structure, and analyzed their photophysical properties. We used organometallic methods to synthesize the CdTe QDs in a noncoordinating solvent. To avoid being quenched by air, ligands, solvent, or other compounds, CdS shell was successfully deposited on the CdTe QDs by different methods, including the slow injection method, the successive ion layer adsorption and reaction (SILAR) method, and thermal-cycling coupled single precursor method (TC-SP). Our final product, quasi-type- II CdTe/CdS core/shell QDs were able to emit at 770 nm with a fluorescence quantum yield as high as 70%. We also tried to deposit a second shell ZnS on CdTe/CdS core/shell QDs since some compounds can quench CdTe/CdS core/shell QDs. Even though different methods were used to deposit ZnS shell on the CdTe/CdS core/shell QDs, CdTe/CdS/ZnS core/shell/shell QDs still can be quenched. Furthermore, the CdTe/CdS core/shell and CdTe/CdS/ZnS core/shell/shell QDs were transferred into aqueous phase, phosphate buffered saline or deionized water, by switching the hydrophilic ligands (thiol or PEG ligands). The thioglycolic acid (TGA)-capped CdTe/CdS core/shell QDs can be kept in aqueous phase with high fluorescence quantum yield (60%--70%) for more than two months. However, some other compounds in organic or

  19. Silicon in the Earth's core.

    PubMed

    Georg, R Bastian; Halliday, Alex N; Schauble, Edwin A; Reynolds, Ben C

    2007-06-28

    Small isotopic differences between the silicate minerals in planets may have developed as a result of processes associated with core formation, or from evaporative losses during accretion as the planets were built up. Basalts from the Earth and the Moon do indeed appear to have iron isotopic compositions that are slightly heavy relative to those from Mars, Vesta and primitive undifferentiated meteorites (chondrites). Explanations for these differences have included evaporation during the 'giant impact' that created the Moon (when a Mars-sized body collided with the young Earth). However, lithium and magnesium, lighter elements with comparable volatility, reveal no such differences, rendering evaporation unlikely as an explanation. Here we show that the silicon isotopic compositions of basaltic rocks from the Earth and the Moon are also distinctly heavy. A likely cause is that silicon is one of the light elements in the Earth's core. We show that both the direction and magnitude of the silicon isotopic effect are in accord with current theory based on the stiffness of bonding in metal and silicate. The similar isotopic composition of the bulk silicate Earth and the Moon is consistent with the recent proposal that there was large-scale isotopic equilibration during the giant impact. We conclude that Si was already incorporated as a light element in the Earth's core before the Moon formed.

  20. Academic Rigor: The Core of the Core

    ERIC Educational Resources Information Center

    Brunner, Judy

    2013-01-01

    Some educators see the Common Core State Standards as reason for stress, most recognize the positive possibilities associated with them and are willing to make the professional commitment to implementing them so that academic rigor for all students will increase. But business leaders, parents, and the authors of the Common Core are not the only…

  1. Gases in ice cores

    PubMed Central

    Bender, Michael; Sowers, Todd; Brook, Edward

    1997-01-01

    Air trapped in glacial ice offers a means of reconstructing variations in the concentrations of atmospheric gases over time scales ranging from anthropogenic (last 200 yr) to glacial/interglacial (hundreds of thousands of years). In this paper, we review the glaciological processes by which air is trapped in the ice and discuss processes that fractionate gases in ice cores relative to the contemporaneous atmosphere. We then summarize concentration–time records for CO2 and CH4 over the last 200 yr. Finally, we summarize concentration–time records for CO2 and CH4 during the last two glacial–interglacial cycles, and their relation to records of global climate change. PMID:11607743

  2. Air resources

    SciTech Connect

    1995-10-01

    This section describes the ambient (surrounding) air quality of the TVA region, discusses TVA emission contributions to ambient air quality, and identifies air quality impacts to human health and welfare. Volume 2 Technical Document 2, Environmental Consequences, describes how changes in TVA emissions could affect regional air quality, human health, environmental resources, and materials. The primary region of the affected environment is broadly defined as the state of Tennessee, as well as southern Kentucky, western Virginia, southern West Virginia, western North Carolina, and northern Georgia, Alabama, and Mississippi. This area represents the watershed of the Tennessee River and the 201 counties of the greater TVA service area. Emissions from outside the Tennessee Valley region contribute to air quality in the Valley. Also, TVA emissions are transported outside the Valley and have some impact on air quality beyond the primary study area. Although the study area experiences a number of air quality problems, overall air quality is good.

  3. Core-nucleus distortation in hypernuclei

    SciTech Connect

    Bodmer, A.R.; Usmani, Q.N.

    1995-08-01

    We are completing a study of the effects of the spherical distortion of the {open_quotes}core{close_quotes} nucleus by the {Lambda} in a hypernucleus. The response of the core was determined by an appropriately chosen energy-density functional which depends, in particular, on the nuclear compressibility. The forcing action of the A is determined by the nuclear density dependence of the {Lambda} binding in nuclear matter which is obtained from our work on the {Lambda} single-particle energies. Because of the strongly repulsive {Lambda}NN forces, this {Lambda} binding {open_quotes}saturates{close_quotes} at a density close to the central density of nuclei, and results in a reduced core-nucleus distortion much less than would otherwise be obtained. The effects of the core distortion then turn out to be very small even for quite light hypernuclei. This result justifies the assumption that spherical core nuclei are effectively undistorted in a hypernucleus.

  4. Air Pollution.

    ERIC Educational Resources Information Center

    Gilpin, Alan

    A summary of one of our most pressing environmental problems, air pollution, is offered in this book by the Director of Air Pollution Control for the Queensland (Australia) State Government. Discussion of the subject is not restricted to Queensland or Australian problems and policies, however, but includes analysis of air pollution the world over.…

  5. Core merging and stratification following giant impact

    NASA Astrophysics Data System (ADS)

    Landeau, Maylis; Olson, Peter; Deguen, Renaud; Hirsh, Benjamin H.

    2016-10-01

    A stratified layer below the core-mantle boundary has long been suspected on the basis of geomagnetic and seismic observations. It has been suggested that the outermost core has a stratified layer about 100 km thick that could be due to the diffusion of light elements. Recent seismological evidence, however, supports a layer exceeding 300 km in thickness of enigmatic origin. Here we show from turbulent mixing experiments that merging between projectile and planetary core following a giant impact can lead to a stratified layer at the top of the core. Scaling relationships between post-impact core structure and projectile properties suggest that merging between Earth's protocore and a projectile core that is enriched in light elements and 20 times less massive can produce the thick stratification inferred from seismic data. Our experiments favour Moon-forming impact scenarios involving a projectile smaller than the proto-Earth and suggest that entrainment of mantle silicates into the protocore led to metal-silicate equilibration under extreme pressure-temperature conditions. We conclude that the thick stratified layer detected at the top of Earth's core can be explained as a vestige of the Moon-forming giant impact during the late stages of planetary accretion.

  6. Air Cleaning Technologies

    PubMed Central

    2005-01-01

    to remove airborne pathogens from room air depends on several factors, including the airflow rate through the unit’s filter and the airflow patterns in the room. Tested under a variety of conditions, in-room air cleaners, including portable or ceiling mounted units with either a HEPA or a non-HEPA filter, portable units with UVGI lights only, or ceiling mounted units with combined HEPA filtration and UVGI lights, have been estimated to be between 30% and 90%, 99% and 12% and 80% effective, respectively. However, and although their effectiveness is variable, the United States Centers for Disease Control and Prevention has acknowledged in-room air cleaners as alternative technology for increasing room ventilation when this cannot be achieved by the building’s HVAC system with preference given to fixed recirculating systems over portable ones. Importantly, the use of an in-room air cleaner does not preclude either the need for health care workers and visitors to use personal protective equipment (N95 mask or equivalent) when entering AII rooms or health care facilities from meeting current regulatory requirements for airflow rates (ventilation rates) in buildings and airflow differentials for effective negative-pressure rooms. The Plasmacluster ion technology, developed in 2000, is an air purification technology. Its manufacturer, Sharp Electronics Corporation, says that it can disable airborne microorganisms through the generation of both positive and negative ions. (1) The functional unit is the hydroxyl, which is a molecule comprised of one oxygen molecule and one hydrogen atom. Plasmacluster ion air purifier uses a multilayer filter system composed of a prefilter, a carbon filter, an antibacterial filter, and a HEPA filter, combined with an ion generator to purify the air. The ion generator uses an alternating plasma discharge to split water molecules into positively and negatively charged ions. When these ions are emitted into the air, they are surrounded by

  7. Core Forensics: Earth's Accretion and Differentiation

    NASA Astrophysics Data System (ADS)

    Badro, J.; Brodholt, J. P.; Siebert, J.; Piet, H.; Ryerson, F. J.

    2013-12-01

    Earth's accretion and its primitive differentiation are intimately interlinked processes. One way to constrain accretionary processes is by looking at the major differentiation event that took place during accretion: core formation. Understanding core formation and core composition can certainly shed a new light on early and late accretionary processes. On the other hand, testing certain accretionary models and hypothesis (fluxes, chemistries, timing) allows -short of validating them- at the very least to unambiguously refute them, through the 'filter'' of core formation and composition. Earth's core formed during accretion as a result of melting, phase-separation, and segregation of accretionary building blocks (from meteorites to planetesimals). The bulk composition of the core and mantle depends on the evolution (pressure, temperature, composition) of core extraction during accretion. The entire process left a compositional imprint on both reservoirs: (1) in the silicate Earth, in terms of siderophile trace-element (Ni, Co, V, Cr, among others) concentrations and isotopic fractionation (Si, Cu, among others), a record that is observed in present-day mantle rocks; and (2) on the core, in terms of major element composition and light elements dissolved in the metal, a record that is observed by seismology through the core density-deficit. This imprint constitutes actually a fairly impressive set of evidence (siderophile element concentration and fractionation, volatile and siderophile element isotopic fractionation), can be used today to trace back the primordial processes that occurred 4.5 billion years ago. We are seeking to provide an overhaul of the standard core formation/composition models, by using a new rationale that bridges geophysics and geochemistry. The new ingredients are (1) new laser-heated diamond anvil cell partitioning data, dramatically extending the previous P-T conditions for experimental work, (2) ab initio molecular dynamics calculations to

  8. Suspended core photonic microcells for sensing and device applications.

    PubMed

    Wang, Chao; Jin, Wei; Ma, Jun; Wang, Ying; Ho, Hoi Lut; Shi, Xin

    2013-06-01

    In-line fiber-optic microcells are fabricated by postprocessing NKT LMA10 photonic crystal fibers. The cells are suspended core (SC) elements created by locally inflating some of the air holes while the core is being tapered. Based on a SC microcell with six air holes, a cantilever beam accelerometer is demonstrated. The microcells could also be used as gain and absorption cells for amplifier and spectroscopy applications. PMID:23722776

  9. Investigating the relationship between k-core and s-core network decompositions

    NASA Astrophysics Data System (ADS)

    Eidsaa, Marius; Almaas, Eivind

    2016-05-01

    Network decomposition methods, such as the much used k-core analysis, are able to identify globally central regions of networks. The decomposition approaches are hierarchical and identify nested sets of nodes with increasing centrality properties. While most studies have been concerned with unweighted networks, i.e. k-core analysis, recent works have introduced network decomposition methods that apply to weighted networks. Here, we investigate the relationship between k-core decomposition for unweighted networks and s-core decomposition for weighted networks by systematically employing a link-weight scheme that gradually discretizes the link weights. We applied this approach to the Erdős-Rényi model and the scale-free configuration model for five different weight distributions, and two empirical networks, the US air traffic network and a Facebook network. We find that (1) both uniformly random and positively correlated link-weight distributions give rise to highly stable s-core decompositions with respect to discretization levels. (2) For negatively correlated link-weight distributions, the resulting s-core decomposition has no similarity to the k-cores. Since several combinations of network topology and link-weight distributions give rise to a core-structure that is highly similar to the full s-core for a large range of link-discretization levels, it is possible to significantly speed up the numerical s-core analysis for these situations.

  10. k-core percolation on multiplex networks

    NASA Astrophysics Data System (ADS)

    Azimi-Tafreshi, N.; Gómez-Gardeñes, J.; Dorogovtsev, S. N.

    2014-09-01

    We generalize the theory of k-core percolation on complex networks to k-core percolation on multiplex networks, where k ≡(k1,k2,...,kM). Multiplex networks can be defined as networks with vertices of one kind but M different types of edges, representing different types of interactions. For such networks, the k-core is defined as the largest subgraph in which each vertex has at least ki edges of each type, i =1,2,...,M. We derive self-consistency equations to obtain the birth points of the k-cores and their relative sizes for uncorrelated multiplex networks with an arbitrary degree distribution. To clarify our general results, we consider in detail multiplex networks with edges of two types and solve the equations in the particular case of Erdős-Rényi and scale-free multiplex networks. We find hybrid phase transitions at the emergence points of k-cores except the (1,1)-core for which the transition is continuous. We apply the k-core decomposition algorithm to air-transportation multiplex networks, composed of two layers, and obtain the size of (k1,k2)-cores.

  11. Development of an Air Transport Type A Fissile Package

    SciTech Connect

    Blanton, P.; Ebert, K.

    2011-07-13

    This paper presents the summary of testing by the Savannah River National Laboratory (SRNL) to support development of a light weight (<140 lbs) air transport qualified Type A Fissile Packaging. The package design incorporates features and materials specifically designed to minimize packaging weight. The light weight package is being designed to provide confinement to the contents when subjected to the normal and hypothetical conditions required of an air transportable Type A Fissile radioactive material shipping package. The objective of these tests was to provide design input to the final design for the LORX Type A Fissile Air Transport Packaging when subjected to the performance requirements of the drop, crush and puncture probe test of 10CFR71. The post test evaluation of the prototype packages indicates that all of the tested designs would satisfactorily confine the content within the packaging. The differences in the performance of the prototypes varied significantly depending on the core materials and their relative densities. Information gathered from these tests is being used to develop the final design for the Department of Homeland Security.

  12. Light Pollution

    ERIC Educational Resources Information Center

    Riegel, Kurt W.

    1973-01-01

    Outdoor lighting is light pollution which handicaps certain astronomical programs. Protective measures must be adopted by the government to aid observational astronomy without sacrificing legitimate outdoor lighting needs. (PS)

  13. Light Duty.

    ERIC Educational Resources Information Center

    Rogers, Jeff

    1996-01-01

    Discusses multipurpose athletic-field lighting specifications to enhance lighting quality and reduce costs. Topics discussed include lamp choice, lighting spillover and glare prevention, luminary assemblies and poles, and the electrical dimming and switching systems. (GR)

  14. Study on sensing characteristics of three-core photonic crystal fibers

    NASA Astrophysics Data System (ADS)

    Chen, Yue-e.; Shao, Qiu-feng; Wang, Yong

    2014-12-01

    Total-internal-reflection (TIR) typed fiber sensors based on photonic crystal fibers (PCFs) are made by filling samples into PCF cladding holes, where the interaction of light wave occurs between the evanescent wave of fiber core and the filled samples. This can avoid common transmission losses caused by fiber surface roughness. The interaction region of the evanescent wave in a PCF and the filled samples are almost coincident, so increasing fiber length can enhance the light-matter interaction and enable accurate detection of tiny changes of samples. However, it is difficult to inject sample materials into stomatal cladding of TIR-typed PCF sensors due to small volume of pores. In addition, the energy utilization rates of TIR-typed sensors are relatively low, only about 6%. A main influencing factor on the sensitivity of TIR-typed PCF sensors is the power fraction of pores in the whole cross section. In order to improve the sensitivity, one can elevate the power fraction of PCF pores. Based on the above considerations, a novel three-core double-clad PCF is designed, where samples are injected into the middle hole and two Yd-doped cores are arranged on its two sides for active excitation. Our theoretical calculation and experimental test show that this kind of structure can not only increase the coupling efficiency of the evanescent wave into the air holes effectively, but also gain higher detection sensitivity of trace samples.

  15. Principles of light energy management

    NASA Technical Reports Server (NTRS)

    Davis, N.

    1994-01-01

    Six methods used to minimize excess energy effects associated with lighting systems for plant growth chambers are reviewed in this report. The energy associated with wall transmission and chamber operating equipment and the experimental requirements, such as fresh air and internal equipment, are not considered here. Only the energy associated with providing and removing the energy for lighting is considered.

  16. Lighting system with thermal management system

    DOEpatents

    Arik, Mehmet; Weaver, Stanton; Stecher, Thomas; Seeley, Charles; Kuenzler, Glenn; Wolfe, Jr., Charles; Utturkar, Yogen; Sharma, Rajdeep; Prabhakaran, Satish; Icoz, Tunc

    2013-05-07

    Lighting systems having unique configurations are provided. For instance, the lighting system may include a light source, a thermal management system and driver electronics, each contained within a housing structure. The light source is configured to provide illumination visible through an opening in the housing structure. The thermal management system is configured to provide an air flow, such as a unidirectional air flow, through the housing structure in order to cool the light source. The driver electronics are configured to provide power to each of the light source and the thermal management system.

  17. Lighting system with thermal management system

    DOEpatents

    Arik, Mehmet; Weaver, Stanton Earl; Stecher, Thomas Elliot; Seeley, Charles Erklin; Kuenzler, Glenn Howard; Wolfe, Jr., Charles Franklin; Utturkar, Yogen Vishwas; Sharma, Rajdeep; Prabhakaran, Satish; Icoz, Tunc

    2015-02-24

    Lighting systems having unique configurations are provided. For instance, the lighting system may include a light source, a thermal management system and driver electronics, each contained within a housing structure. The light source is configured to provide illumination visible through an opening in the housing structure. The thermal management system is configured to provide an air flow, such as a unidirectional air flow, through the housing structure in order to cool the light source. The driver electronics are configured to provide power to each of the light source and the thermal management system.

  18. Lighting system with thermal management system

    DOEpatents

    Arik, Mehmet; Weaver, Stanton Earl; Stecher, Thomas Elliot; Seeley, Charles Erklin; Kuenzler, Glenn Howard; Wolfe, Jr, Charles Franklin; Utturkar, Yogen Vishwas; Sharma, Rajdeep; Prabhakaran, Satish; Icoz, Tunc

    2016-10-11

    Lighting systems having unique configurations are provided. For instance, the lighting system may include a light source, a thermal management system and driver electronics, each contained within a housing structure. The light source is configured to provide illumination visible through an opening in the housing structure. The thermal management system is configured to provide an air flow, such as a unidirectional air flow, through the housing structure in order to cool the light source. The driver electronics are configured to provide power to each of the light source and the thermal management system.

  19. Lighting system with thermal management system

    SciTech Connect

    Arik, Mehmet; Weaver, Stanton Earl; Stecher, Thomas Elliot; Seeley, Charles Erklin; Kuenzler, Glenn Howard; Wolfe, Jr., Charles Franklin; Utturkar, Yogen Vishwas; Sharma, Rajdeep; Prabhakaran, Satish; Icoz, Tunc

    2015-08-25

    Lighting systems having unique configurations are provided. For instance, the lighting system may include a light source, a thermal management system and driver electronics, each contained within a housing structure. The light source is configured to provide illumination visible through an opening in the housing structure. The thermal management system is configured to provide an air flow, such as a unidirectional air flow, through the housing structure in order to cool the light source. The driver electronics are configured to provide power to each of the light source and the thermal management system.

  20. Core Design Applications

    1995-07-12

    CORD-2 is intended for core desigh applications of pressurized water reactors. The main objective was to assemble a core design system which could be used for simple calculations (such as frequently required for fuel management) as well as for accurate calculations (for example, core design after refueling).