iss031e143143

NASA Image and Video Library

2012-06-19

ISS031-E-143143 (19 June 2012) --- Al Jubayl, Saudi Arabia at night is featured in this image photographed by an Expedition 31 crew member on the International Space Station. The city of Al Jubayl (or Jubail) is located on the Saudi Arabian coastline of the Persian Gulf. The city has a history extending back more than 7,000 years, but since 1975 it has been associated with the heavy industries of petrochemical refining and production, fertilizer production and steel works. At night, these industrial areas form a brightly lit region (center) to the south of the residential and commercial center of Al Jubayl (characterized by green-gray lighting). An artificial peninsula extending into the Persian Gulf to the northeast hosts supertanker docks and petroleum storage facilities. The Persian Gulf to the north and northeast is devoid of lights; likewise, the open desert to the south-southeast provides a stark contrast to the well-lit urban and industrial areas. A bright circle of light located within the heavy industrial area (center) cannot be resolved in this photograph, but is likely a concentration of lights associated with ongoing processing or construction activities. The approximate scale of the feature ? hundreds of meters in diameter ? is consistent with multiple stationary light sources, particularly if the light from those sources is accentuated due to the camera?s low light settings.

Real-time data-intensive computing

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

Parkinson, Dilworth Y., E-mail: dyparkinson@lbl.gov; Chen, Xian; Hexemer, Alexander

2016-07-27

Today users visit synchrotrons as sources of understanding and discovery—not as sources of just light, and not as sources of data. To achieve this, the synchrotron facilities frequently provide not just light but often the entire end station and increasingly, advanced computational facilities that can reduce terabytes of data into a form that can reveal a new key insight. The Advanced Light Source (ALS) has partnered with high performance computing, fast networking, and applied mathematics groups to create a “super-facility”, giving users simultaneous access to the experimental, computational, and algorithmic resources to make this possible. This combination forms an efficientmore » closed loop, where data—despite its high rate and volume—is transferred and processed immediately and automatically on appropriate computing resources, and results are extracted, visualized, and presented to users or to the experimental control system, both to provide immediate insight and to guide decisions about subsequent experiments during beamtime. We will describe our work at the ALS ptychography, scattering, micro-diffraction, and micro-tomography beamlines.« less

An elegant route to overcome fundamentally-limited light extraction in AlGaN deep-ultraviolet light-emitting diodes: Preferential outcoupling of strong in-plane emission

PubMed Central

Lee, Jong Won; Kim, Dong Yeong; Park, Jun Hyuk; Schubert, E. Fred; Kim, Jungsub; Lee, Jinsub; Kim, Yong-Il; Park, Youngsoo; Kim, Jong Kyu

2016-01-01

While there is an urgent need for semiconductor-based efficient deep ultraviolet (DUV) sources, the efficiency of AlGaN DUV light-emitting diodes (LEDs) remains very low because the extraction of DUV photons is significantly limited by intrinsic material properties of AlGaN. Here, we present an elegant approach based on a DUV LED having multiple mesa stripes whose inclined sidewalls are covered by a MgF2/Al omni-directional mirror to take advantage of the strongly anisotropic transverse-magnetic polarized emission pattern of AlGaN quantum wells. The sidewall-emission-enhanced DUV LED breaks through the fundamental limitations caused by the intrinsic properties of AlGaN, thus shows a remarkable improvement in light extraction as well as operating voltage. Furthermore, an analytic model is developed to understand and precisely estimate the extraction of DUV photons from AlGaN DUV LEDs, and hence to provide promising routes for maximizing the power conversion efficiency. PMID:26935402

An elegant route to overcome fundamentally-limited light extraction in AlGaN deep-ultraviolet light-emitting diodes: Preferential outcoupling of strong in-plane emission

NASA Astrophysics Data System (ADS)

Lee, Jong Won; Kim, Dong Yeong; Park, Jun Hyuk; Schubert, E. Fred; Kim, Jungsub; Lee, Jinsub; Kim, Yong-Il; Park, Youngsoo; Kim, Jong Kyu

2016-03-01

While there is an urgent need for semiconductor-based efficient deep ultraviolet (DUV) sources, the efficiency of AlGaN DUV light-emitting diodes (LEDs) remains very low because the extraction of DUV photons is significantly limited by intrinsic material properties of AlGaN. Here, we present an elegant approach based on a DUV LED having multiple mesa stripes whose inclined sidewalls are covered by a MgF2/Al omni-directional mirror to take advantage of the strongly anisotropic transverse-magnetic polarized emission pattern of AlGaN quantum wells. The sidewall-emission-enhanced DUV LED breaks through the fundamental limitations caused by the intrinsic properties of AlGaN, thus shows a remarkable improvement in light extraction as well as operating voltage. Furthermore, an analytic model is developed to understand and precisely estimate the extraction of DUV photons from AlGaN DUV LEDs, and hence to provide promising routes for maximizing the power conversion efficiency.

Seeing the Light (LBNL Science at the Theater)

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

Brunger, Axel; Segalman, Rachel; Westphal, Andrew

2011-09-12

Berkeley Lab's Science at the Theater event "Seeing the Light" took place on Sept 12, 2011, at Berkeley Repertory's Roda Theatre. Learn how the Advanced Light Source is improving medicine, paving the way for clean energy, changing the future of computers, and much more. Featured speakers are Berkeley Lab's Roger Falcone, Rachel Segalman, Andrew Westphal, and Stanford University's Axel Brunger. Rachel Segalman: The future of clean energy technology relies on a better understanding of materials at the nanoscale. Berkeley Lab's Rachel Segalman uses the ALS to conduct this research, which could lead to improved photovoltaics and fuel cells. Axel Brunger:more » Improved treatment for human diseases hinges on understanding molecular-scale processes. Stanford University's Axel Brunger will discuss a new melanoma drug that was developed by a local company, Plexxikon, using the ALS for X-ray data collection. Andrew Westphal: What's comet dust made of? Andrew Westphal of UC Berkeley's Space Sciences Laboratory uses the ALS to study comet dust and interplanetary space dust collected by a NASA spacecraft. Moderated by Roger Falcone, Division Director of the Advanced Light Source« less

Field errors in hybrid insertion devices

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

Schlueter, R.D.

1995-02-01

Hybrid magnet theory as applied to the error analyses used in the design of Advanced Light Source (ALS) insertion devices is reviewed. Sources of field errors in hybrid insertion devices are discussed.

Chemical Crystallography at the Advanced Light Source

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

McCormick, Laura; Giordano, Nico; Teat, Simon

Chemical crystallography at synchrotrons was pioneered at the Daresbury SRS station 9.8. The chemical crystallography beamlines at the Advanced Light Source seek to follow that example, with orders of magnitude more flux than a lab source, and various in situ experiments. This article thus attempts to answer why a chemist would require synchrotron X-rays, to describe the techniques available at the ALS chemical crystallography beamlines, and place the current facilities in a historical context.

Chemical Crystallography at the Advanced Light Source

DOE PAGES

McCormick, Laura; Giordano, Nico; Teat, Simon; ...

2017-12-18

Chemical crystallography at synchrotrons was pioneered at the Daresbury SRS station 9.8. The chemical crystallography beamlines at the Advanced Light Source seek to follow that example, with orders of magnitude more flux than a lab source, and various in situ experiments. This article thus attempts to answer why a chemist would require synchrotron X-rays, to describe the techniques available at the ALS chemical crystallography beamlines, and place the current facilities in a historical context.

Presenting new exoplanet candidates for the CoRoT chromatic light curves

NASA Astrophysics Data System (ADS)

Boufleur, Rodrigo; Emilio, Marcelo; Andrade, Laerte; Janot-Pacheco, Eduardo; De La Reza, Ramiro

2015-08-01

One of the most promising topics of modern Astronomy is the discovery and characterization of extrasolar planets due to its importance for the comprehension of planetary formation and evolution. Missions like MOST (Microvariability and Oscillations of Stars Telescope) (Walker et al., 2003) and especially the satellites dedicated to the search for exoplanets CoRoT (Convection, Rotation and planetary Transits) (Baglin et al., 1998) and Kepler (Borucki et al., 2003) produced a great amount of data and together account for hundreds of new discoveries. An important source of error in the search for planets with light curves obtained from space observatories are the displacements occuring in the data due to external causes. This artificial charge generation phenomenon associated with the data is mainly caused by the impact of high energy particles onto the CCD (Pinheiro da Silva et al. 2008), although other sources of error, not as well known also need to be taken into account. So, an effective analysis of the light curves depends a lot on the mechanisms employed to deal with these phenomena. To perform our research, we developed and applied a different method to fix the light curves, the CDAM (Corot Detrend Algorithm Modified), inspired by the work of Mislis et al. (2012). The paradigms were obtained using the BLS method (Kovács et al., 2002). After a semiautomatic pre-analysis associated with a visual inspection of the planetary transits signatures, we obtained dozens of exoplanet candidates in very good agreement with the literature and also new unpublished cases. We present the study results and characterization of the new cases for the chromatic channel public light curves of the CoRoT satellite.

The Effects of Primary Light Sources on Worker Performance and Alertness

NASA Technical Reports Server (NTRS)

Wong, Lily; Caddick, Zachary; Kuriyagawa, Yukiyo; Flynn-Evans, Erin

2017-01-01

Traditional office buildings use a variety of primary light sources (e.g., LED/fluorescent lights). As interest in LEED certified office buildings increase and research has shown that enhanced lighting design improves human performance and alertness (Viola et al., 2008; Juslén & Tenner, 2005; Edwards & Torcellini, 2002), more office buildings are incorporating a daylighting design. We investigated the differences between employee performance and alertness in two different building types (daylight vs. artificial light). We hypothesized that employee performance and sleep duration would be improved in a building designed to increase exposure to natural daylight compared to traditional office settings.

Recent results and future plans for a 45 actuator adaptive x-ray optics experiment at the advanced light source

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

Brejnholt, Nicolai F., E-mail: brejnholt1@llnl.gov; Poyneer, Lisa A.; Hill, Randal M.

2016-07-27

We report on the current status of the Adaptive X-ray Optics project run by Lawrence Livermore National Laboratory (LLNL). LLNL is collaborating with the Advanced Light Source (ALS) to demonstrate a near real-time adaptive X-ray optic. To this end, a custom-built 45 cm long deformable mirror has been installed at ALS beamline 5.3.1 (end station 2) for a two-year period that started in September 2014. We will outline general aspects of the instrument, present results from a recent experimental campaign and touch on future plans for the project.

Investigation of interface property in Al/SiO2/ n-SiC structure with thin gate oxide by illumination

NASA Astrophysics Data System (ADS)

Chang, P. K.; Hwu, J. G.

2017-04-01

The reverse tunneling current of Al/SiO2/ n-SiC structure employing thin gate oxide is introduced to examine the interface property by illumination. The gate current at negative bias decreases under blue LED illumination, yet increases under UV lamp illumination. Light-induced electrons captured by interface states may be emitted after the light sources are off, leading to the recovery of gate currents. Based on transient characteristics of gate current, the extracted trap level is close to the light energy for blue LED, indicating that electron capture induced by lighting may result in the reduction of gate current. Furthermore, bidirectional C- V measurements exhibit a positive voltage shift caused by electron trapping under blue LED illumination, while a negative voltage shift is observed under UV lamp illumination. Distinct trapping and detrapping behaviors can be observed from variations in I- V and C- V curves utilizing different light sources for 4H-SiC MOS capacitors with thin insulators.

EDITORIAL: Special Issue on advanced and emerging light sources Special Issue on advanced and emerging light sources

NASA Astrophysics Data System (ADS)

Haverlag, Marco; Kroesen, Gerrit; Ferguson, Ian

2011-06-01

The papers in this special issue of Journal of Physics D: Applied Physics (JPhysD) originate from the 12th International Symposium on the Science and Technology of Light Sources and the 3rd International Conference on White LEDs and Solid State Lighting, held 11-16 July 2010 at Eindhoven University. Abstracts of all papers presented at this combined conference were published in the Conference Proceedings LS-WLED 2010 by FAST-LS, edited by M Haverlag, G M W Kroesen and T Taguchi. Special issues of the previous three LS conferences have been well-cited and have proven to be an important source of information for the lighting community. The 2010 LS-Symposium was a combined conference with the White LED Conference in order to enhance the scope of this conference series towards new light source technologies such as LEDs and OLEDs, and this co-operation will be continued in the future. Given the faster technology development in these areas it was also decided to shorten the interval between conferences from three to two years. Well over 200 invited presentations, landmark presentations and poster contributions were presented at the 2010 LS-Symposium. The organizing committee have selected from these a number of outstanding contributions with a high technological content and invited the authors to submit a full paper in JPhysD. The criteria were that the work should not be a repetition of the work already published in the Proceedings, but should be new, complete, within the scope of JPhysD, and meeting the normal quality standards of this journal. After peer review a combined set of 18 papers is published in this JPhysD special issue. In addition, a number of lighting-application-orientated papers will be published in a special issue of Journal of Light & Visual Environment later in 2011. The papers in this special issue of JPhysD show that research in the science and technology of light sources still covers a broad set of subject areas which includes both 'classical' discharge light sources and (O)LED sources, and new concepts are still being added to the range of technologies that are being used in practice. A truly classic aspect of lamp operation is lumen maintenance, and despite being in use for almost 50 years, Na/Sc quartz metal halide lamps until recently still suffered from a strong lumen depreciation over life. This issue has been resolved to a large extent with the introduction of high-frequency operation. In the paper of Van Erk et al, indications are given as to why this mode of operation is so successful. Another classic theme in the area of discharge lamp sources is ignition, still a major issue. In two consecutive papers by Sobota et al, several aspects of the cold ignition of ceramic metal halide lamps are discussed, including statistical delay effects, the role of the driving voltage, and ignition aids. The ignition becomes more complex when mercury is left out of a metal halide lamp and this is clearly shown in the paper by Estupiñán et al. When not buffered by mercury, water impurities will give rise to the formation of hydrogen iodide, which is very volatile and a strongly electronegative species, thereby hampering the ignition process. Mercury-free metal halide lamps will potentially show very different spectral properties. This is shown in the paper by Käning et al, where use has been made of the ongoing improvements in ceramic lamp technology to make lamps with a high rare-earth iodide content. It was found that in such lamps the contribution of molecular lines can become so important that some lines even become self-reversed. This opens new possibilities for making high-quality white light sources without mercury while retaining the use of electrodes. High rare-earth content also changes the behaviour of electrodes as a result of the lowering of the work function due to gas-phase emitter effects. In the paper by Reinelt et al some clear examples of this effect are investigated as well as their dependence on the operational frequency in ceramic metal halide lamps. Despite the fact that ceramic metal halide lamps with electrodes have already been on the market for more than 15 years, the latest developments in materials and lamp-shaping technologies continue to push the limits of efficiency and colour quality of these lamps. In an effort to clarify the energy balance of these lamps, Rijke et al have shown that it is possible to deduce from integrated sphere measurements in the visible and IR region the complete energy balance of such lamps. This method will provide valuable insights to push the efficacy of HID technologies even further. New concepts based on discharges are also being proposed and some of these are also being introduced to the market. It is interesting to note that all of these concepts are either mercury-free or can easily be adapted to mercury-free versions. One such contender is the electrodeless HID lamp. In the paper by Gilliard et al it is shown how a cavity resonator can be effectively used to couple power into a capacitively coupled electrodeless metal halide lamp. In contrast, the paper by Hilbig et al shows a concept in which the power is inductively coupled. Both methods potentially offer more freedom in salt choice, and this is used in the paper by Hilbig et al to test various new molecular radiators including some oxygen-containing molecules. With a larger choice of applicable salt systems, it becomes even more important to know the thermodynamical properties of rare-earth molecules. A nice overview of these properties for the mono-halides is given in the paper by Mucklejohn. Operating at lower pressures is another concept; employment of phosphor-converted DBD and microplasma lamps is studied in the papers by Eden et al and Guivan et al. A relatively new concept based on pulsed operation of pure Xe discharges and phosphor conversion is described by Motomura et al. These papers show that there is still an abundance of developments in discharge-based light sources. However, the progress in the last few years in LED and OLED sources has been even greater. In the editorial for the LS-11 conference by previous guest editor David Wharmby, it was stated that most LED lighting was still mostly used for signalling and decorative sources. In the three years that have passed, things have changed considerably and we now see LED light sources entering every application, ranging from street lighting and parking lots to shop lighting and even greenhouses. Currently LED prices for traditional lighting applications are high, but they are dropping rapidly. The papers published in this special issue give some indications of things to come. The paper by Jamil et al deals with the possibility of using silicon wafers as substrate material instead of the now commonly used (but more expensive) sapphire substrates. This is attractive from a cost price point of view, but leads to an increased lattice mismatch and therefore strain-induced defects. In this paper it is shown that when using intermediate matching layers it is possible to retain the same electrical and optical properties as with structures on sapphire. Another aspect that directly relates to cost is efficiency and droop in green InGaN devices, which is addressed in the paper by Lee et al. They show that by providing a flow of trymethylindium prior to the growth of the quantum wells it is possible to significantly increase the internal quantum efficiency of green LEDs. Improvement of the optical out-coupling of InGaN LEDs is discussed by Mak et al, and it is found that localized plasmon resonance of metallic nanoparticles (and especially silver) can help to increase the optical out-coupling in the wavelength region of interest. Nanoparticles in the form of ZnO nanorods are described by Willander et al as a possibility for phosphor-free wavelength conversion on polymer (O)LEDs. More advanced functions besides light emission can be achieved with OLEDs and this is demonstrated in the article by Generali et al which describes various aspects of organic light-emitting (field) transistors based on different substrates. The guest editors of this special issue of Journal of Physics D: Applied Physics would like to thank all the colleagues who helped us identify this exhaustive collection of papers. There are too many people to list here, but we know them well and are grateful for their help.

A broadband LED source in visible to short-wave-infrared wavelengths for spectral tumor diagnostics

NASA Astrophysics Data System (ADS)

Hayashi, Daiyu; van Dongen, Anne Marie; Boerekamp, Jack; Spoor, Sandra; Lucassen, Gerald; Schleipen, Jean

2017-06-01

Various tumor types exhibit the spectral fingerprints in the absorption and reflection spectra in visible and especially in near- to short-wave-infrared wavelength ranges. For the purpose of spectral tumor diagnostics by means of diffuse reflectance spectroscopy, we developed a broadband light emitting diode (LED) source consisting of a blue LED for optical excitation, Lu3Al5O12:Ce3+,Cr3+ luminescent garnet for visible to near infrared emissions, and Bismuth doped GeO2 luminescent glass for near-infrared to short-wave infrared emissions. It emits broad-band light emissions continuously in 470-1600 nm with a spectral gap at 900-1000 nm. In comparison to the currently available broadband light sources like halogen lamps, high-pressure discharge lamps and super continuum lasers, the light sources of this paper has significant advantages for spectral tissue diagnostics in high-spectral stability, improved light coupling to optical fibers, potential in low light source cost and enabling battery-drive.

Cation dynamics of molecular Hydrogen in the presence of a strong laser field, preliminary results

NASA Astrophysics Data System (ADS)

Gatton, A.; Champenois, E.; Larsen, K.; Shivaram, N.; Bakhti, S.; Iskander, W.; Sievert, T.; Reedy, D.; Weller, M.; Williams, J. B.; Landers, A.; Weber, Th.

2017-04-01

We present preliminary results from a new 2-color laser+synchrotron Cold Target Recoil Ion Momentum Spectrometer (COLTRIMS) experiment in which we overlap a pulsed laser (1030 nm , 12 ps , 5 *1011 W / cm2) with light from beamline 10 . 0 . 1 (18 . 56 eV , 80 ps , 50 meV resolution) at the Advanced Light Source at Lawrence Berkeley National Lab. The data (absent the laser) shows asymmetric proton emission in the fragmenting hydrogen cation due to the retro-action of the photoelectron Coulomb potential, as reported recently by Waitz et al.. Preliminary analysis hints that this effect exists and may even be enhanced in the laser dressed states of the dissociating cation. Of even more interest, preliminary analysis hints at the signature of light induced conical intersections in the dissociation of the laser dressed hydrogen cations, as recently reported by Natan et al.. This research used the Advanced Light Source and was supported by DOE-BES under contract No. DE-AC02-05CH11231 and DE-FG02-86ER13491, the ALS Doctoral Fellowship in Residence, and the DFG and DAAD.

An elegant route to overcome fundamentally-limited light extraction in AlGaN deep-ultraviolet light-emitting diodes: preferential outcoupling of strong in-plane emission (Conference Presentation)

NASA Astrophysics Data System (ADS)

Kim, Jong Kyu; Lee, Jong Won; Kim, Dong-Yeong; Park, Jun Hyuk; Schubert, E. Fred; Kim, Jungsub; Kim, Yong-Il

2016-09-01

AlGaN-based deep ultraviolet (DUV) light-emitting diodes (LEDs) are being developed for their numerous applications such as purification of air and water, sterilization in food processing, UV curing, medical-, and defense-related light sources. However, external quantum efficiency (EQE) of AlGaN-based DUV LEDs is very poor (<5% for 250nm) particularly due to low hole concentration and light extraction efficiency (LEE). Conventional LEE-enhancing techniques used for GaInN-based visible LEDs turned out to be ineffective for DUV LEDs due to difference in intrinsic material property between GaInN and AlGaN (Al< 30%). Unlike GaInN visible LEDs, DUV light from a high Al-content AlGaN active region is strongly transverse-magnetic (TM) polarized, that is, the electric field vector is parallel to the (0001) c-axis and shows strong sidewall emission through m- or a-plane due to crystal-field split-off hole band being top most valence band. Therefore, a new LEE-enhancing approach addressing the unique intrinsic property of AlGaN DUV LEDs is strongly desired. In this study, an elegant approach based on a DUV LED having multiple mesa stripes whose inclined sidewalls are covered by a MgF2/Al omni-directional mirror to take advantage of the strongly anisotropic transverse-magnetic polarized emission pattern of AlGaN quantum wells is presented. The sidewall-emission-enhanced DUV LED breaks through the fundamental limitations caused by the intrinsic properties of AlGaN, thus shows a remarkable improvement in light extraction as well as operating voltage simultaneously. Furthermore, an analytic model is developed to understand and precisely estimate the extraction of DUV photons from AlGaN DUV LEDs, and hence to provide promising routes to maximize the power conversion efficiency.

Estimation of neutron dose equivalent at the mezzanine of the Advanced Light Source and the laboratory boundary using the ORNL program MORSE.

PubMed

Sun, R K

1990-12-01

To investigate the radiation effect of neutrons near the Advanced Light Source (ALS) at Lawrence Berkeley Laboratory (LBL) with respect to the neutron dose equivalents in nearby occupied areas and at the site boundary, the neutron transport code MORSE, from Oak Ridge National Laboratory (ORNL), was used. These dose equivalents result from both skyshine neutrons transported by air scattering and direct neutrons penetrating the shielding. The ALS neutron sources are a 50-MeV linear accelerator and its transfer line, a 1.5-GeV booster, a beam extraction line, and a 1.9-GeV storage ring. The most conservative total occupational-dose-equivalent rate in the center of the ALS mezzanine, 39 m from the ALS center, was found to be 1.14 X 10(-3) Sv y-1 per 2000-h "occupational" year, and the total environmental-dose-equivalent rate at the ALS boundary, 125 m from the ALS center, was found to be 3.02 X 10(-4) Sv y-1 per 8760-h calendar year. More realistic dose-equivalent rates, using the nominal (expected) storage-ring current, were calculated to be 1.0 X 10(-4) Sv y-1 and 2.65 X 10(-5) Sv y-1 occupational year and calendar year, respectively, which are much lower than the DOE reporting levels.

Black Pine Circle Project

ScienceCinema

Mytko, Christine

2018-05-18

A group of seventh graders from Black Pine Circle school in Berkeley had the opportunity to experience the Advanced Light Source (ALS) as "users" via a collaborative field trip and proposal project. The project culminated with a field trip to the ALS for all seventh graders, which included a visit to the ALS data visualization room, a diffraction demonstration, a beamline tour, and informative sessions about x-rays and tomography presented by ALS scientists.

Black Pine Circle Project

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

Mytko, Christine

2014-03-31

A group of seventh graders from Black Pine Circle school in Berkeley had the opportunity to experience the Advanced Light Source (ALS) as "users" via a collaborative field trip and proposal project. The project culminated with a field trip to the ALS for all seventh graders, which included a visit to the ALS data visualization room, a diffraction demonstration, a beamline tour, and informative sessions about x-rays and tomography presented by ALS scientists.

Microwave discharge electrodeless lamps (MDEL). III. A novel tungsten-triggered MDEL device emitting VUV and UVC radiation for use in wastewater treatment.

PubMed

Horikoshi, Satoshi; Miura, Takashi; Kajitani, Masatsugu; Serpone, Nick

2008-03-01

Exposure to low doses of the xenoestrogen bisphenol A (BPA) and to the hormonal 2,4-dichlorophenoxyacetic acid (2,4-D) herbicide, an environmental endocrine disruptor, can have serious health consequences such as the induction of mammary gland ductal hyperplasias and carcinoma (LaChapelle et al., Reprod. Toxicol., 2007, 23, 20; Murray et al., Reprod. Toxicol., 2007, 23, 383). To the extent that these toxins are present in wastewaters (Donald et al., Sci. Total Environ. 1999, 231, 173; Brotons et al., Environ. Health Perspect. 1994, 103, 608; Olea et al., Environ. Health Perspect. 1996, 104, 298; Biles et al., J. Agric. Food Chem. 1997, 45, 3541; Markey et al., J. Steroid Biochem. Mol. Biol., 2003, 83, 235), we examined their oxidative destruction in aqueous media by a novel light source. A tungsten-triggered microwave discharge electrodeless lamp (W-MDEL) was fabricated for possible use in wastewater treatment using vacuum UV-transparent quartz in which a tungsten trigger, also embedded in quartz, was attached to the MDEL to aid in the self-ignition of the lamp on irradiation at low microwave power levels. The quantity of mercury gas in the W-MDEL was optimized by monitoring the continuous radiation and peak intensities of the emitted light in the vacuum UV (VUV) and UVC regions. The usefulness of the W-MDEL device was assessed through the degradation of 2,4-D and BPA in air-equilibrated aqueous media and in oxygen-saturated aqueous media. Enhanced degradation of these two xenoestrogenic toxins was achieved by increasing the number of W-MDEL devices while keeping constant the microwave radiation feeding each W-MDEL lamp. This novel lamp provides an additional light source in the photooxidation of environmental contaminants without the need for a metal-oxide photocatalyst. Under our conditions, process dynamics using the W-MDEL light source are greater than with the more conventional photochemical methods that employ low-pressure Hg arc electrode lamps in synthetic quartz to degrade these two toxic contaminants.

Optically pumped cerium-doped LiSrAlF{sub 6} and LiCaAlF{sub 6}

DOEpatents

Marshall, C.D.; Payne, S.A.; Krupke, W.F.

1996-05-14

Ce{sup 3+}-doped LiSrAlF{sub 6} crystals are pumped by ultraviolet light which is polarized along the c axis of the crystals to effectively energize the laser system. In one embodiment, the polarized fourth harmonic light output from a conventional Nd:YAG laser operating at 266 nm is arranged to pump Ce:LiSrAlF{sub 6} with the pump light polarized along the c axis of the crystal. The Ce:LiSrAlF{sub 6} crystal may be placed in a laser cavity for generating tunable coherent ultraviolet radiation in the range of 280-320 nm. Additionally, Ce-doped crystals possessing the LiSrAlF{sub 6} type of chemical formula, e.g. Ce-doped LiCaAlF{sub 6} and LiSrGaF{sub 6}, can be used. Alternative pump sources include an ultraviolet-capable krypton or argon laser, or ultraviolet emitting flashlamps. The polarization of the pump light will impact operation. The laser system will operate efficiently when light in the 280-320 nm gain region is injected or recirculated in the system such that the beam is also polarized along the c axis of the crystal. The Ce:LiSrAlF{sub 6} laser system can be configured to generate ultrashort pulses, and it may be used to pump other devices, such as an optical parametric oscillator. 10 figs.

Optically pumped cerium-doped LiSrAlF.sub.6 and LiCaAlF.sub.6

DOEpatents

Marshall, Christopher D.; Payne, Stephen A.; Krupke, William F.

1996-01-01

Ce.sup.3+ -doped LiSrAlF.sub.6 crystals are pumped by ultraviolet light which is polarized along the c axis of the crystals to effectively energize the laser system. In one embodiment, the polarized fourth harmonic light output from a conventional Nd:YAG laser operating at 266 nm is arranged to pump Ce:LiSrAlF.sub.6 with the pump light polarized along the c axis of the crystal. The Ce:LiSrAlF.sub.6 crystal may be placed in a laser cavity for generating tunable coherent ultraviolet radiation in the range of 280-320 nm. Additionally, Ce-doped crystals possessing the LiSrAlF.sub.6 type of chemical formula, e.g. Ce-doped LiCaAlF.sub.6 and LiSrGaF.sub.6, can be used. Alternative pump sources include an ultraviolet-capable krypton or argon laser, or ultraviolet emitting flashlamps. The polarization of the pump light will impact operation. The laser system will operate efficiently when light in the 280-320 nm gain region is injected or recirculated in the system such that the beam is also polarized along the c axis of the crystal. The Ce:LiSrAlF.sub.6 laser system can be configured to generate ultrashort pulses, and it may be used to pump other devices, such as an optical parametric oscillator.

Forest Fires as a Possible Source of Isotopically Light Marine Fe Aerosols

NASA Astrophysics Data System (ADS)

Tegler, L. A.; Sherry, A. M.; Romaniello, S. J.; Anbar, A. D.

2016-12-01

Iron (Fe) is an important limiting micronutrient for primary productivity in many high-nutrient, low-chlorophyll (HNLC) regions of the ocean. These marine systems receive a significant fraction of their Fe from atmospheric deposition, which is thought to be dominated by mineral dust with an Fe isotopic composition at or above 0‰. However, Mead et al. (2013) observed isotopically light Fe in marine aerosols smaller than 2.5 μm, which is difficult to reconcile with known sources of marine aerosols. Based on previous experimental work, we hypothesize that biomass burning is the source of isotopically light Fe in atmospheric particles and suggest that biomass burning might represent an underappreciated source of Fe to marine ecosystems. While Guelke et al (2007) demonstrated that Fe in agricultural plants is isotopically light, few studies have examined the Fe isotope composition of naturally occurring forests likely to be a significant source of Fe during forest fires. To address this question, we measured the isotopic composition of Ponderosa pine growing in northern Arizona. Ponderosa pine is one the most common forest types in the western US and thus representative of an important North American fire region. Pine needles were chosen because they are susceptible to complete combustion during biomass burning events. To determine the Fe isotopic composition of pine trees, pine needles were sampled at various tree heights. We found that these samples had δ56Fe values between -1.5 and 0‰, indicating that pine needles can be isotopically light compared to local grasses and soil. These results support the hypothesis that biomass burning may contribute isotopically light Fe to marine aerosols.

Aluminum nitride nanowire light emitting diodes: Breaking the fundamental bottleneck of deep ultraviolet light sources

PubMed Central

Zhao, S.; Connie, A. T.; Dastjerdi, M. H. T.; Kong, X. H.; Wang, Q.; Djavid, M.; Sadaf, S.; Liu, X. D.; Shih, I.; Guo, H.; Mi, Z.

2015-01-01

Despite broad interest in aluminum gallium nitride (AlGaN) optoelectronic devices for deep ultraviolet (DUV) applications, the performance of conventional Al(Ga)N planar devices drastically decays when approaching the AlN end, including low internal quantum efficiencies (IQEs) and high device operation voltages. Here we show that these challenges can be addressed by utilizing nitrogen (N) polar Al(Ga)N nanowires grown directly on Si substrate. By carefully tuning the synthesis conditions, a record IQE of 80% can be realized with N-polar AlN nanowires, which is nearly ten times higher compared to high quality planar AlN. The first 210 nm emitting AlN nanowire light emitting diodes (LEDs) were achieved, with a turn on voltage of about 6 V, which is significantly lower than the commonly observed 20 – 40 V. This can be ascribed to both efficient Mg doping by controlling the nanowire growth rate and N-polarity induced internal electrical field that favors hole injection. In the end, high performance N-polar AlGaN nanowire LEDs with emission wavelengths covering the UV-B/C bands were also demonstrated. PMID:25684335

2 W quasi-white-light based on idler-resonant optical parametric oscillation cascading sum-frequency generation with PPSLT

NASA Astrophysics Data System (ADS)

Zhao, L. N.; Liu, J.; Yuan, Y.; Hu, X. P.; Zhao, G.; Gao, Z. D.; Zhu, S. N.

2012-03-01

We present a high power red-green-blue (RGB) laser light source based on cascaded quasi-phasematched wavelength conversions in a single stoichiometric lithium tantalate. The superiority of the experimental setup is: the facula of the incident beam is elliptical to increase interaction volume, and the cavity was an idler resonant configuration for realizing more efficient red and blue light output. An average power of 2 W of quasi-white-light was obtained by proper combination of the RGB three colors. The conversion efficiency for the power of the quasi-white-light over pump power reached 36%. This efficiency and powerful RGB laser light source has potential applications in laser-based projection display et al.

Violet Laser Diode Enables Lighting Communication.

PubMed

Chi, Yu-Chieh; Huang, Yu-Fang; Wu, Tsai-Chen; Tsai, Cheng-Ting; Chen, Li-Yin; Kuo, Hao-Chung; Lin, Gong-Ru

2017-09-05

Violet laser diode (VLD) based white-light source with high color rendering index (CRI) for lighting communication is implemented by covering with Y 3 Al 5 O 12 :Ce 3+ (YAG:Ce) or Lu 3 Al 5 O 12 :Ce 3+ /CaAlSiN 3 :Eu 2+ (LuAG:Ce/CASN:Eu) phosphorous diffuser plates. After passing the beam of VLD biased at 70 mA (~2I th ) through the YAG:Ce phosphorous diffuser, a daylight with a correlated color temperature (CCT) of 5068 K and a CRI of 65 is acquired to provide a forward error correction (FEC) certified data rate of 4.4 Gbit/s. By using the VLD biased at 122 mA (~3.5I th ) to excite the LuAG:Ce/CASN:Eu phosphorous diffuser with 0.85-mm thickness, a warm white-light source with a CCT of 2700 K and a CRI of 87.9 is obtained at a cost of decreasing transmission capacity to 2.4 Gbit/s. Thinning the phosphor thickness to 0.75 mm effectively reduces the required bias current by 32 mA to achieve the same CCT for the delivered white light, which offers an enlarged CRI of 89.1 and an increased data rate of 4.4 Gbit/s. Further enlarging the bias current to 105 mA remains the white-light transmission capacity at 4.4 Gbit/s but reveals an increased CCT of 3023 K and an upgraded CRI of 91.5.

Long Persistent Light Emitting Diode Indicators

ERIC Educational Resources Information Center

Jia, Dongdong; Ma, Yiwei; Hunter, D. N.

2007-01-01

An undergraduate laboratory was designed for undergraduate students to make long persistent light emitting diode (LED) indicators using phosphors. Blue LEDs, which emit at 465 nm, were characterized and used as an excitation source. Long persistent phosphors, SrAl[subscript 2]O[subscript 4]:Eu[superscript 2+],Dy[superscript 3+] (green) and…

Light curves of the neutron star merger GW170817/SSS17a: Implications for r-process nucleosynthesis

NASA Astrophysics Data System (ADS)

Drout, M. R.; Piro, A. L.; Shappee, B. J.; Kilpatrick, C. D.; Simon, J. D.; Contreras, C.; Coulter, D. A.; Foley, R. J.; Siebert, M. R.; Morrell, N.; Boutsia, K.; Di Mille, F.; Holoien, T. W.-S.; Kasen, D.; Kollmeier, J. A.; Madore, B. F.; Monson, A. J.; Murguia-Berthier, A.; Pan, Y.-C.; Prochaska, J. X.; Ramirez-Ruiz, E.; Rest, A.; Adams, C.; Alatalo, K.; Bañados, E.; Baughman, J.; Beers, T. C.; Bernstein, R. A.; Bitsakis, T.; Campillay, A.; Hansen, T. T.; Higgs, C. R.; Ji, A. P.; Maravelias, G.; Marshall, J. L.; Moni Bidin, C.; Prieto, J. L.; Rasmussen, K. C.; Rojas-Bravo, C.; Strom, A. L.; Ulloa, N.; Vargas-González, J.; Wan, Z.; Whitten, D. D.

2017-12-01

Two neutron stars merging together generate a gravitational wave signal and have also been predicted to emit electromagnetic radiation. When the gravitational wave event GW170817 was detected, astronomers rushed to search for the source using conventional telescopes (see the Introduction by Smith). Coulter et al. describe how the One-Meter Two-Hemispheres (1M2H) collaboration was the first to locate the electromagnetic source. Drout et al. present the 1M2H measurements of its optical and infrared brightness, and Shappee et al. report their spectroscopy of the event, which is unlike previously detected astronomical transient sources. Kilpatrick et al. show how these observations can be explained by an explosion known as a kilonova, which produces large quantities of heavy elements in nuclear reactions.

Enhanced Electron Injection and Exciton Confinement for Pure Blue Quantum-Dot Light-Emitting Diodes by Introducing Partially Oxidized Aluminum Cathode.

PubMed

Wang, Zhibin; Cheng, Tai; Wang, Fuzhi; Bai, Yiming; Bian, Xingming; Zhang, Bing; Hayat, Tasawar; Alsaedi, Ahmed; Tan, Zhan'ao

2018-05-31

Stable and efficient red (R), green (G), and blue (B) light sources based on solution-processed quantum dots (QDs) play important roles in next-generation displays and solid-state lighting technologies. The brightness and efficiency of blue QDs-based light-emitting diodes (LEDs) remain inferior to their red and green counterparts, due to the inherently unfavorable energy levels of different colors of light. To solve these problems, a device structure should be designed to balance the injection holes and electrons into the emissive QD layer. Herein, through a simple autoxidation strategy, pure blue QD-LEDs which are highly bright and efficient are demonstrated, with a structure of ITO/PEDOT:PSS/Poly-TPD/QDs/Al:Al2O3. The autoxidized Al:Al2O3 cathode can effectively balance the injected charges and enhance radiative recombination without introducing an additional electron transport layer (ETL). As a result, high color-saturated blue QD-LEDs are achieved with a maximum luminance over 13,000 cd m -2 , and a maximum current efficiency of 1.15 cd A -1 . The easily controlled autoxidation procedure paves the way for achieving high-performance blue QD-LEDs.

Unusual Black Hole Binary LMC X-3: A Transient High-mass X-Ray Binary That Is Almost Always On?

NASA Astrophysics Data System (ADS)

Torpin, Trevor J.; Boyd, Patricia T.; Smale, Alan P.; Valencic, Lynne A.

2017-11-01

We have analyzed a rich, multimission, multiwavelength data set from the black hole X-ray binary (BHXB) LMC X-3, covering a new anomalous low state (ALS), during which the source flux falls to an unprecedentedly low and barely detectable level, and a more normal low state. Simultaneous X-ray and UV/optical monitoring data from Swift are combined with pointed observations from the Rossi X-ray Timing Explorer (RXTE) and X-ray Multi-Mirror Mission (XMM-Newton) and light curves from the Monitor of All-Sky X-ray Image (MAXI) instrument to compare the source characteristics during the ALS with those seen during the normal low state. An XMM-Newton spectrum obtained during the ALS can be modeled using an absorbed power law with {{Γ }}=1.41+/- 0.65 and a luminosity of 7.97× {10}33 erg s-1 (0.6-5 keV). The Swift X-ray and UV light curves indicate an X-ray lag of ˜8 days as LMC X-3 abruptly exits the ALS, suggesting that changes in the mass accretion rate from the donor drive the X-ray lag. The normal low state displays an asymmetric profile in which the exit occurs more quickly than the entry, with minimum X-ray flux a factor of ˜4300 brighter than during the ALS. The UV brightness of LMC X-3 in the ALS is also fainter and less variable than during normal low states. The existence of repeated ALSs in LMC X-3, as well as a comparison with other BHXBs, implies that it is very close to the transient/persistent X-ray source dividing line. We conclude that LMC X-3 is a transient source that is almost always “on.”

Unusual Black Hole Binary LMC X-3: A Transient High-Mass X-Ray Binary That Is Almost Always On?

NASA Technical Reports Server (NTRS)

Torpin, Trevor J.; Boyd, Patricia T.; Smale, Alan P.; Valencic, Lynne A.

2017-01-01

We have analyzed a rich, multimission, multiwavelength data set from the black hole X-ray binary (BHXB) LMC X-3, covering a new anomalous low state (ALS), during which the source flux falls to an unprecedentedly low and barely detectable level, and a more normal low state. Simultaneous X-ray and UV/optical monitoring data from Swift are combined with pointed observations from the Rossi X-ray Timing Explorer (RXTE) and X-ray Multi- Mirror Mission (XMM-Newton) and light curves from the Monitor of All-Sky X-ray Image (MAXI) instrument to compare the source characteristics during the ALS with those seen during the normal low state. An XMM-Newton spectrum obtained during the ALS can be modeled using an absorbed power law with Gamma = 1.41‚+/- 0.65 and a luminosity of 7.97 x 10(exp 33) erg/s (0.6-5 keV). The Swift X-ray and UV light curves indicate an X-ray lag of approx. 8 days as LMC X-3 abruptly exits the ALS, suggesting that changes in the mass accretion rate from the donor drive the X-ray lag. The normal low state displays an asymmetric profile in which the exit occurs more quickly than the entry, with minimum X-ray flux a factor of approx. 4300 brighter than during the ALS. The UV brightness of LMC X-3 in the ALS is also fainter and less variable than during normal low states. The existence of repeated ALSs in LMC X-3, as well as a comparison with other BHXBs, implies that it is very close to the transient/persistent X-ray source dividing line. We conclude that LMC X-3 is a transient source that is almost always "on."

A non-laser light source for photodynamic therapy: in vitro effects on normal and malignant cells.

PubMed

Kashtan, Hanoch; Haddad, Riad; Greenberg, Ron; Skornick, Yehuda; Kaplan, Ofer

2002-01-01

Photodynamic therapy (PDT) involves the use of photosensitizing drugs combined with light to treat tumors. Laser systems, the current source of light for PDT, have several inherent drawbacks: the spectrum is essentially monochromatic which may be problematic for second generation photosensitizers, the systems are bulky and nearly impossible to move between hospital locations and require complicated electrical and cooling installations, the cost of a typical system is enormous, and its maintenance and operation require highly trained personnel. We now introduce a new non-laser light system, Versa-Light, which appears to work as effectively and has none of the above drawbacks. A series of in vitro studies were performed using various murine and human normal and cancer cells which underwent PDT using aluminum phthalocyanine (AlPcS4) as a photosensitizer and Versa-Light as the light source. PDT of cancer cells at light energy levels of 50, 100 and 200 j/cm2 significantly decreased cell viability. PDT also decreased cell viability of normal murine splenocytes and normal human lymphocytes, but to a lesser extent. The observed significant hyperthermia was light dose-dependent. We believe that Versa-Light can replace laser systems as an enhanced light source for PDT. Further in vitro and pre-clinical studies are in progress.

Commission of a new 2-color laser-synchrotron COLTRIMS experiment

NASA Astrophysics Data System (ADS)

Gatton, A.; Larsen, K.; Champenois, E.; Shivaram, N.; Bakhti, S.; Iskander, W.; Sievert, T.; Reedy, D.; Weller, M.; Williams, J. B.; Landers, A.; Weber, Th.

2017-04-01

We present the technical scheme of a new 2-color laser + synchrotron Cold Target Recoil Ion Momentum Spectrometer (COLTRIMS) experiment in which we overlap a pulsed IR laser (1 MHz , 1030 nm , 12 ps , 5 *1011 W / cm2) with XUV light from beamline 10.0.1 (3 MHz , 18 . 56 eV , 80 ps , 50 meV resolution) at the Advanced Light Source (ALS) at Lawrence Berkeley National Lab. We discuss the experimental methods for overlapping in 3D the co-linear ALS beam (80 um × 100 um) with the laser beam focus (50 um × 50 um) inside the gas jet target with a horizontal length and depth of 1 mm , as well as the timing scheme for achieving sub nanosecond stable synchrolock of the two pulse trains such that they are overlapped in time at the gas jet target every third ALS pulse. We present a definitive 2 color signal observed in Helium excited by 23 . 74 eV photons from the ALS to the 1s4p 1P state, and then ionized by the laser. We intend to use this scheme to study dissociation dynamics of excited molecules in the presence of a strong laser field. This research used the Advanced Light Source and was supported by DOE-BES under Contract No. DE-AC02-05CH11231 and DE-FG02-86ER13491, the ALS Doctoral Fellowship in Residence, and the DFG and DAAD.

Aerosol source apportionment based on multi-wavelength photoacoustic light absorption measurements: a simulation method for system's optimisation

NASA Astrophysics Data System (ADS)

Simon, Károly; Ajtai, Tibor; Kiss-Albert, Gergely; Utry, Noémi; Pintér, Máté; Szabó, Gábor; Bozóki, Zoltán

2017-04-01

Aerosol source apportionment is currently one of the outstanding challenges for environmental monitoring. In most cases atmospheric aerosol is a heterogeneous mixture as it typically originates from various sources. Consequently, each aerosol type has distinct chemical and physical properties. Contrary to chemical properties, optical absorption and size distribution of airborne particles can be measured in real time with high time resolution i.e. their measurement facilitates real time source apportionment (Favez et al (2009), Ajtai et al (2011), Favez et al (2010)). The wavelength dependency of the optical absorption coefficient (OAC) is usually characterised by the Absorption Angström Exponent (AAE). So far, the selection of light sources (lasers) into a photoacoustic aerosol measuring system was based on rule of thumb type estimations only. Recently, we proposed a simulation method that can be used to estimate the accuracy of aerosol source apportionment in case of a dual wavelength photoacoustic system (Simon et al., (2017)). This simulation is based on the assumption that the atmospheric aerosol load is dominated by two distinct sources and each of them is strongly light absorbing with specific AAE values. This is a typical scenario e.g. for urban measurements under wintry conditions when dominating aerosol sources are fossil fuel and wood burning with characteristic AAE 1 and 2, respectively. The wavelength pair of 405 and 1064 nm was found to be optimal for source apportionment in this case. In the presented study we investigated the situation when there are aerosol components with only slightly different AAE values and searched for a photoacoustic system which is optimal for distinguishing these components. Ajtai, T.; Filep, Á.; Utry, N.; Schnaiter, M.; Linke, C.; Bozóki, Z.; Szabó, G. and Leisner T. (2011) Journal of Aerosol Science 42, 859-866. Favez, O.; Cachier, H.; Sciare, J.; Sarda-Estève, R. and Martinon, L. (2009) Atmospheric Environment 43, 3640-3644. Favez, O.; El Haddad, I.; Piot, C.; Boréave, A.; Abidi, E.; Marchand, N.; Jaffrezo, J. L.; Besombes, J. L.; Personnaz, M. B.; Sciare, J.; Wortham, H.; George, C. and D'Anna, B. (2010), Atmos. Chem. Phys. 10, 5295-5314. Simon, K.A.; Ajtai, T; Gulyas, G; Utry, N; Pinter, M; Szabo, G. and Bozoki, Bozoki, Z. (2017), Journal of Aerosol Science 104, 10-15.

Towards a 4{sup th} generation storage ring at the Canadian Light Source

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

Dallin, Les; Wurtz, Ward

2016-07-27

Demands from beamline scientists for more brilliant sources of synchrotron radiation have resulted in the emergence of 4{sup th} generation (diffraction-limited) storage rings. The practical development of the multi-bend achromat (MBA) concept by MAX IV lab has spurred many synchrotron light sources around the world to develop similar machines. For existing facilities two options are available: upgrading existing machines or building a new structure. The Canadian Light Source (CLS) has explored both options. For a new low emittance source in the existing CLS tunnel a decrease in electron energy would be required. A machine similar to the ALS upgrade couldmore » be contemplated. To achieve low emittance at our present energy of 2.9 GeV a new storage ring is desirable. Several options have been investigated. These designs use extremely strong focusing magnets to achieve extremely low emittances in compact lattice achromats.« less

Tailored white light emission in Eu3+/Dy3+ doped tellurite glass phosphors containing Al3+ ions

NASA Astrophysics Data System (ADS)

Walas, Michalina; Piotrowski, Patryk; Lewandowski, Tomasz; Synak, Anna; Łapiński, Marcin; Sadowski, Wojciech; Kościelska, Barbara

2018-05-01

Tellurite glass systems modified by addition of aluminum fluoride AlF3 have been successfully synthesized as host matrices for optically active rare earth ions RE3+ (RE3+ = Eu3+, Dy3+). Samples with different Eu3+ to Dy3+ molar ratio have been studied in order to determine possibility of white light emission via UV excitation. Structural investigations confirmed amorphous character of materials whereas spectroscopic studies brought more insight into glass network's nature. FTIR results shown presence of two features related to tellurite glass matrix (in 490-935 cm-1 spectral region) and another one (940-1250 cm-1) due to aluminum addition. Especially, Al-O and Te-O-Al bonds of AlO4 tetrahedrons have been found. AlO4 units are considered as glass formers that improve network's strength and thermal resistivity against devitrification. Based on XPS studies of Al3+ photoelectron band the existence of Al-O and also Al-F bonds have been examined. Moreover, signals originating from Eu3+ and Dy3+ have been found confirming their valence state. Luminescence results revealed possibility of simultaneous UV excitation of Eu3+ and Dy3+ ions. Excitation with λexc = 390 and 393 nm resulted in white light generation starting from warm white to neutral and cool white depending on Eu3+ concentration and used excitation wavelength. Additionally, increase of decay lifetime of Eu3+ induced by Al3+ presence have been revealed based on luminescence decay analysis. Thus, tellurite glass systems modified by AlF3 and doped with Eu3+/Dy3+ may be considered as promising candidates for white light emitting sources.

Formation and Coloring Mechanism of Typical Aluminosilicate Clay Minerals for CoAl2O4 Hybrid Pigment Preparation

PubMed Central

Zhang, Anjie; Mu, Bin; Wang, Xiaowen; Wen, Lixin; Wang, Aiqin

2018-01-01

Different kinds of aluminosilicate minerals were employed to fabricate CoAl2O4 hybrid pigment for studying its formation and coloring mechanism. It revealed that the color of the obtained hybrid pigments was determined by the content of Al2O3 and lightness of clay minerals. The higher the Al2O3 content and the lightness of clay minerals, the better the color parameters of hybrid pigments. During the preparation of hybrid pigments, CoAl2O4 nanoparticles were confined to be loaded on the surface of the aluminosilicate minerals, which effectively prevented from the aggregation and the size increase of CoAl2O4 nanoparticles. What's more, aluminosilicate mineral might be an ideal natural aluminum source to compensate the aluminum loss due to the dissolution of Al(OH)3 at alkaline medium during precursor preparation, keeping an optimum molar ratio of Co2+/Al3+ for formation of spinel CoAl2O4 pigments in the process of high-temperature crystallization. PMID:29725589

Formation and Coloring Mechanism of Typical Aluminosilicate Clay Minerals for CoAl2O4 Hybrid Pigment Preparation.

PubMed

Zhang, Anjie; Mu, Bin; Wang, Xiaowen; Wen, Lixin; Wang, Aiqin

2018-01-01

Different kinds of aluminosilicate minerals were employed to fabricate CoAl 2 O 4 hybrid pigment for studying its formation and coloring mechanism. It revealed that the color of the obtained hybrid pigments was determined by the content of Al 2 O 3 and lightness of clay minerals. The higher the Al 2 O 3 content and the lightness of clay minerals, the better the color parameters of hybrid pigments. During the preparation of hybrid pigments, CoAl 2 O 4 nanoparticles were confined to be loaded on the surface of the aluminosilicate minerals, which effectively prevented from the aggregation and the size increase of CoAl 2 O 4 nanoparticles. What's more, aluminosilicate mineral might be an ideal natural aluminum source to compensate the aluminum loss due to the dissolution of Al(OH) 3 at alkaline medium during precursor preparation, keeping an optimum molar ratio of Co 2+ /Al 3+ for formation of spinel CoAl 2 O 4 pigments in the process of high-temperature crystallization.

SIBYLS - a SAXS and Protein Crystallography Beamline at the ALS

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

Trame, C.; MacDowell, A.A.; Celestre, R.S.

2004-05-12

The new Structurally Integrated BiologY for Life Sciences (SIBYLS) beamline at the Advanced Light Source will be dedicated to Macromolecular Crystallography (PX) and Small Angle X-ray Scattering (SAXS). SAXS will provide structural information of macromolecules in solutions and will complement high resolution PX studies on the same systems but in a crystalline state. The x-ray source is one of the 5 Tesla superbend dipoles recently installed at the ALS that allows for a hard x-ray program to be developed on the relatively low energy Advanced Light Source (ALS) ring (1.9 GeV). The beamline is equipped with fast interchangeable monochromator elements,more » consisting of either a pair of single Si(111) crystals for crystallography, or a pair of multilayers for the SAXS mode data collection (E/{delta}E{approx}1/110). Flux rates with Si(111) crystals for PX are measured as 2x1011 hv/sec through a 100{mu}m pinhole at 12.4KeV. For SAXS the flux is up to 3x1013photons/sec at 10KeV with all apertures open when using the multilayer monochromator elements. The performance characteristics of this unique beamline will be described.« less

Combustion Science for Cleaner Fuels

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

Ahmed, Musahid

2014-10-17

Musahid Ahmed discusses how he and his team use the Advanced Light Source (ALS) to study combustion chemistry at our '8 Big Ideas' Science at the Theater event on October 8th, 2014, in Oakland, California.

Combustion Science for Cleaner Fuels

ScienceCinema

Ahmed, Musahid

2018-01-16

Musahid Ahmed discusses how he and his team use the Advanced Light Source (ALS) to study combustion chemistry at our '8 Big Ideas' Science at the Theater event on October 8th, 2014, in Oakland, California.

Comparative effects of exposure to different light sources (He-Ne laser, InGaAl diode laser, a specific type of noncoherent LED) on skin blood flow for the head.

PubMed

Pöntinen, P J; Aaltokallio, T; Kolari, P J

1996-01-01

This study assessed the effects of optic stimuli emitted by three different light sources on head skin blood flow. The irradiation effects of the He-Ne laser (632.8 nm, 10 mW, total energy appr. 9.4 J), the InGaAl diode laser (670 nm, 60 mW, appr. 108 J) and monochromatic light (635 nm, 112.5 mW, appr. 202.5 J) were measured using laser Doppler technology. The corresponding fluences (energy densities) varied from 0.01 J/cm2 (He-Ne) to a range of 0.12-0.72 J/cm2 (InGaAl) and 0.22-1.36 J/cm2 (LED). The investigation was completed under single-blind, placebo-controlled conditions where the subjects (10 male healthy volunteers) were exposed on two occasions to the placebo (LED)-device against the laser (He-Ne or InGaAl). A short lasting vasodilation, a 54 per cent increase (p < 0.05) in skin blood flow was seen after the InGaAl irradiation (fluences between 0.12-0.36 J/cm2) whereas the non-coherent monochromatic irradiation (0.68-1.36 J/cm2) used in this particular study decreased blood flow by 36 per cent (p < 0.05). The He-Ne irradiation (0.01 J/cm2) had no effect. Skin temperature changes were insignificant. Skin blood flow changes seemed to be related more on radiant exposures then coherency.

Advanced light source master oscillator

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

Lo, C.C.; Taylor, B.; Baptiste, K.

1989-03-01

The Master Oscillator of the Advanced Light Source operates at a frequency of 499.654 MHz which is the 328th harmonic of the storage ring. The oscillator is capable of providing up to a maximum of {plus minus} 500 KHz frequency deviation for various experimental purposes. Provisions for external signal injection as well as using an external signal source have been designed into the unit. A power distribution system has also been included to provide signals for various parts of the ALS machine and user requirements. The Master Oscillator is made up with modules housed in a Euro chassis. 4 refs.,more » 7 figs.« less

Finite-key security analysis of quantum key distribution with imperfect light sources

DOE PAGES

Mizutani, Akihiro; Curty, Marcos; Lim, Charles Ci Wen; ...

2015-09-09

In recent years, the gap between theory and practice in quantum key distribution (QKD) has been significantly narrowed, particularly for QKD systems with arbitrarily flawed optical receivers. The status for QKD systems with imperfect light sources is however less satisfactory, in the sense that the resulting secure key rates are often overly dependent on the quality of state preparation. This is especially the case when the channel loss is high. Very recently, to overcome this limitation, Tamaki et al proposed a QKD protocol based on the so-called 'rejected data analysis', and showed that its security in the limit of infinitelymore » long keys is almost independent of any encoding flaw in the qubit space, being this protocol compatible with the decoy state method. Here, as a step towards practical QKD, we show that a similar conclusion is reached in the finite-key regime, even when the intensity of the light source is unstable. More concretely, we derive security bounds for a wide class of realistic light sources and show that the bounds are also efficient in the presence of high channel loss. Our results strongly suggest the feasibility of long distance provably secure communication with imperfect light sources.« less

Generation of White Light from Dysprosium-Doped Strontium Aluminate Phosphor by a Solid-State Reaction Method

NASA Astrophysics Data System (ADS)

Sahu, Ishwar Prasad; Bisen, D. P.; Brahme, N.; Tamrakar, Raunak Kumar

2016-04-01

A single-host lattice, white light-emitting SrAl2O4:Dy3+ phosphor was synthesized by a solid-state reaction method. The crystal structure of prepared SrAl2O4:Dy3+ phosphor was in a monoclinic phase with space group P21. The chemical composition of the sintered SrAl2O4:Dy3+ phosphor was confirmed by the energy dispersive x-ray spectroscopy technique. Under ultra-violet excitation, the characteristic emissions of Dy3+ are peaking at 475 nm, 573 nm and 660 nm, originating from the transitions of 4F9/2 → 6H15/2, 4F9/2 →&!nbsp; 6H13/2 and 4F9/2 → 6H11/2 in the 4f9 configuration of Dy3+ ions. Commission International de I'Eclairage color coordinates of SrAl2O4:Dy3+ are suitable for white light-emitting phosphor. In order to investigate the suitability of the samples as white color light sources for industrial uses, correlated color temperature (CCT) and color rendering index (CRI) values were calculated. Values of CCT and CRI were found well within the defined acceptable range. Mechanoluminescence (ML) intensity of SrAl2O4:Dy3+ phosphor increased linearly with increasing impact velocity of the moving piston. Thus, the present investigation indicates piezo-electricity was responsible for producing ML in sintered SrAl2O4:Dy3+ phosphor. Decay rates of the exponential decaying period of the ML curves do not change significantly with impact velocity. The photoluminescence and ML results suggest that the synthesized SrAl2O4:Dy3+ phosphor was useful for the white light-emitting diodes and stress sensor respectively.

Light-chain cardiac amyloidosis: strategies to promote early diagnosis and cardiac response

PubMed Central

Grogan, Martha; Dispenzieri, Angela; Gertz, Morie A

2017-01-01

Amyloid light chain (AL) amyloidosis is a systemic disease characterised by the aggregation of misfolded immunoglobulin light chain (LC), predominantly in the heart and kidneys, causing organ failure. If untreated, the median survival of patients with cardiac AL amyloidosis is 6 months from the onset of heart failure. Protracted time to establish a diagnosis, often lasting >1 year, is a frequent factor in poor treatment outcomes. Cardiologists, to whom patients are often referred, frequently miss the opportunity to diagnose cardiac AL amyloidosis. Nearly all typical cardiac support measures, with the exception of diuretics, are ineffective and may even worsen clinical symptoms, emphasising the need for accurate diagnosis. Patients with severe cardiac involvement face poor outcomes; heart transplantation is rarely an option because of multiorgan involvement, rapid clinical decline and challenges in predicting which patients will respond to treatment of the underlying plasma cell disorder. Early diagnosis and prompt treatment with ‘source therapies’ that limit the production of amyloidogenic LC are associated with better survival and improvement in organ function after a median of 2.4 months following haematological complete response. However, organ recovery is often incomplete because these source therapies do not directly target deposited amyloid. Emerging amyloid-directed therapies may attenuate, and potentially reverse, organ dysfunction by clearing existing amyloid and inhibiting fibril formation of circulating aggregates. Improved recognition of AL amyloidosis by cardiologists allows for earlier treatment and improved outcomes. PMID:28456755

Commissioning of BL 7.2, the new diagnostic beam line at the ALS

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

Sannibale, Fernando; Baum, Dennis; Biocca, Alan

2004-06-29

BL 7.2 is a new beamline at the Advanced Light Source (ALS) of the Lawrence Berkeley National Laboratory (LBNL) dedicated to electron beam diagnostics. The system, which is basically a hard x-ray pinhole camera, was installed in the storage ring in August 2003 and commissioning with the ALS electron beam followed immediately after. In this paper the commissioning results are presented together with the description of the relevant measurements performed for the beamline characterization.

Electronic structure of p-type transparent conducting oxide CuAlO2

NASA Astrophysics Data System (ADS)

Mo, Sung-Kwan; Yoon, Joonseok; Liu, Xiaosong; Yang, Wanli; Mun, Bongjin; Ju, Honglyoul

2014-03-01

CuAlO2 is a prototypical p-type transparent conducting oxide. Despite its importance for potential applications and number of studies on its band structure and gap characteristics, experimental study on the momentum-resolved electronic structure has been lacking. We present angle-resolved photoemission data on single crystalline CuAlO2 using synchrotron light source to reveal complete band structure. Complemented by the x-ray absorption and emission spectra, we also study band gap characteristics and compare them with theory.

Transport properties of doped AlP for the development of conductive AlP/GaP distributed Bragg reflectors and their integration into light-emitting diodes

NASA Astrophysics Data System (ADS)

Hestroffer, Karine; Sperlich, Dennis; Dadgostar, Shabnam; Golz, Christian; Krumland, Jannis; Masselink, William Ted; Hatami, Fariba

2018-05-01

The transport properties of n- and p-doped AlP layers grown by gas-source molecular beam epitaxy are investigated. n- and p-types of conductivities are achieved using Si and Be with peak room-temperature mobilities of 59.6 cm2/Vs and 65.0 cm2/Vs for electrons and holes, respectively. Si-doping results are then used for the design of n-doped AlP/GaP distributed Bragg reflectors (DBRs) with an ohmic resistance of about 7.5 ± 0.1 Ω. The DBRs are integrated as bottom mirrors in GaP-based light-emitting diodes (LEDs) containing InGaP/GaP quantum dots. The functionality of the LED structure and the influence of the DBRs on the InGaP/GaP electroluminescence spectra are demonstrated.

Does Light from Steady Sources Bear Any Observable Imprint of the Dispersive Intergalactic Medium?

NASA Astrophysics Data System (ADS)

Lieu, Richard; Duan, Lingze

2018-02-01

There has recently been some interest in the prospect of detecting ionized intergalactic baryons by examining the properties of incoherent light from background cosmological sources, namely quasars. Although the paper by Lieu et al. proposed a way forward, it was refuted by the later theoretical work of Hirata & McQuinn and the observational study of Hales et al. In this paper we investigate in detail the manner in which incoherent radiation passes through a dispersive medium both from the frameworks of classical and quantum electrodynamics, leading us to conclude that the premise of Lieu et al. would only work if the pulses involved are genuinely classical ones containing many photons per pulse; unfortunately, each photon must not be treated as a pulse that is susceptible to dispersive broadening. We are nevertheless able to change the tone of the paper at this juncture by pointing out that because current technology allows one to measure the phase of individual modes of radio waves from a distant source, the most reliable way of obtaining irrefutable evidence of dispersion, namely via the detection of its unique signature of a quadratic spectral phase, may well be already accessible. We demonstrate how this technique is only applied to measure the column density of the ionized intergalactic medium.

SIBYLS - A SAXS and protein crystallography beamline at the ALS

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

Trame, Christine; MacDowell, Alastair A.; Celestre, Richard S.

2003-08-22

The new Structurally Integrated BiologY for Life Sciences (SIBYLS) beamline at the Advanced Light Source will be dedicated to Macromolecular Crystallography (PX) and Small Angle X-ray Scattering (SAXS). SAXS will provide structural information of macromolecules in solutions and will complement high resolution PX studies on the same systems but in a crystalline state. The x-ray source is one of the 5 Tesla superbend dipoles recently installed at the ALS that allows for a hard x-ray program to be developed on the relatively low energy Advanced Light Source (ALS) ring (1.9 GeV). The beamline is equipped with fast interchangeable monochromator elements,more » consisting of either a pair of single Si(111) crystals for crystallography, or a pair of multilayers for the SAXS mode data collection (E/{Delta}E {approx} 1/110). Flux rates with Si(111) crystals for PX are measured as 2 x 10{sup 11} hv/sec/400 mA through a 100 {micro}m pinhole at 12.4 KeV. For SAXS the flux is up to 3 x 10{sup 13} photons/sec at 10 KeV with all apertures open when using the multilayer monochromator elements. The performance characteristics of this unique beamline will be described.« less

Multi-wavelength mid-IR light source for gas sensing

NASA Astrophysics Data System (ADS)

Karioja, Pentti; Alajoki, Teemu; Cherchi, Matteo; Ollila, Jyrki; Harjanne, Mikko; Heinilehto, Noora; Suomalainen, Soile; Viheriälä, Jukka; Zia, Nouman; Guina, Mircea; Buczyński, Ryszard; Kasztelanic, Rafał; Kujawa, Ireneusz; Salo, Tomi; Virtanen, Sami; Kluczyński, Paweł; Sagberg, Hâkon; Ratajczyk, Marcin; Kalinowski, Przemyslaw

2017-02-01

Cost effective multi-wavelength light sources are key enablers for wide-scale penetration of gas sensors at Mid-IR wavelength range. Utilizing novel Mid-IR Si-based photonic integrated circuits (PICs) filter and wide-band Mid-IR Super Luminescent Light Emitting Diodes (SLEDs), we show the concept of a light source that covers 2.5…3.5 μm wavelength range with a resolution of <1nm. The spectral bands are switchable and tunable and they can be modulated. The source allows for the fabrication of an affordable multi-band gas sensor with good selectivity and sensitivity. The unit price can be lowered in high volumes by utilizing tailored molded IR lens technology and automated packaging and assembling technologies. The status of the development of the key components of the light source are reported. The PIC is based on the use of micron-scale SOI technology, SLED is based on AlGaInAsSb materials and the lenses are tailored heavy metal oxide glasses fabricated by the use of hot-embossing. The packaging concept utilizing automated assembly tools is depicted. In safety and security applications, the Mid-IR wavelength range covered by the novel light source allows for detecting several harmful gas components with a single sensor. At the moment, affordable sources are not available. The market impact is expected to be disruptive, since the devices currently in the market are either complicated, expensive and heavy instruments, or the applied measurement principles are inadequate in terms of stability and selectivity.

Accurate photometric light curves of the lensed components of Q2237+0305 derived with an optimal image subtraction technique: Evidence for microlensing in image A

NASA Astrophysics Data System (ADS)

Moreau, O.; Libbrecht, C.; Lee, D.-W.; Surdej, J.

2005-06-01

Using an optimal image subtraction technique, we have derived the V and R light curves of the four lensed QSO components of Q2237+0305 from the monitoring CCD frames obtained by the GLITP collaboration with the 2.6 m NOT telescope in 1999/2000 (Alcalde et al. 2002). We give here a detailed account of the data reduction and analysis and of the error estimates. In agreement with Woźniak et al. (2000a,b), the good derived photometric accuracy of the GLITP data allows to discuss the possible interpretation of the light curve of component A as due to a microlensing event taking place in the deflecting galaxy. This interpretation is strengthened by the colour dependence of the early rise of the light curve of component A, as it probably corresponds to a caustics crossing by the QSO source.

Stellar Temporal Intensity Interferometry

NASA Astrophysics Data System (ADS)

Kian, Tan Peng

Stellar intensity interferometry was developed by Hanbury-Brown & Twiss [1954, 1956b, 1957, 1958] to bypass the diffraction limit of telescope apertures, with successful measurements including the determination of 32 stellar angular diameters using the Narrabri Stellar Intensity Interferometer [Hanbury-Brown et al., 1974]. This was achieved by measuring the intensity correlations between starlight received by a pair of telescopes separated by varying baselines b which, by invoking the van Cittert-Zernicke theorem [van Cittert, 1934; Zernicke, 1938], are related to the angular intensity distributions of the stellar light sources through a Fourier transformation of the equal-time complex degree of coherence gamma(b) between the two telescopes. This intensity correlation, or the second order correlation function g(2) [Glauber, 1963], can be described in terms of two-photoevent coincidence measurements [Hanbury-Brown, 1974] for our use of photon-counting detectors. The application of intensity interferometry in astrophysics has been largely restricted to the spatial domain but not found widespread adoption due to limitations by its signal-to-noise ratio [Davis et al., 1999; Foellmi, 2009; Jensen et al., 2010; LeBohec et al., 2008, 2010], although there is a growing movement to revive its use [Barbieri et al., 2009; Capraro et al., 2009; Dravins & Lagadec, 2014; Dravins et al., 2015; Dravins & LeBohec, 2007]. In this thesis, stellar intensity interferometry in the temporal domain is investigated instead. We present a narrowband spectral filtering scheme [Tan et al., 2014] that allows direct measurements of the Lorentzian temporal correlations, or photon bunching, from the Sun, with the preliminary Solar g(2)(tau = 0) = 1.3 +/- 0.1, limited mostly by the photon detector response [Ghioni et al., 2008], compared to the theoretical value of g(2)(0) = 2. The measured temporal photon bunching signature of the Sun exceeded the previous records of g(2)(0) = 1.03 [Karmakar et al., 2012] and g(2)(0) = 1.04 [Liu et al., 2014] by an order of magnitude. In order to study possible effects of atmospheric turbulence [Blazej et al., 2008; Cavazzani et al., 2012; Dravins et al., 1997] on temporal intensity interferometry, the filtering scheme was improved so that the required integration time of measurement reduced from 45 minutes previously to only 4 minutes, which allowed for timing correlation measurements of Sunlight in 1° intervals of elevation angular position to probe the atmospheric dependence. The instruments were used to measure the temporal photon bunching signal of the Sun from 11:36 am to 5:36 pm, covering Solar elevation angles from approximately 70° just before noon to about 20° by the evening, corresponding to different depths of atmospheric air column [Bennett, 1982; Marini & Murray, 1973] the sunlight passed through. The thereby obtained Solar g (2)(tau = 0) = 1.693 +/- 0.003 exceeded our previous record, due to improved suppression of the blackbody spectrum outside the target bandwidth. The Solar photon bunching signature was compatible with control measurements of an Argon arc lamp with g(2)(tau = 0) = 1.687 +/- 0.004, which served as a blackbody light source of temperature T = 6000K. This suggests that the atmospheric and weather conditions have no measurable effects on temporal intensity interferometry for a 2GHz optical bandwidth after narrowband spectral filtering. The instruments were exposed to a light source simulating astrophysical scenarios, created by mixing the blackbody radiation from the Argon arc lamp with laser light at 513.8 nm. The spectral filtering scheme was able to isolate the laser light by filtering the blackbody spectrum to only Deltanu FWHM ≈ 2GHz and thus suppressing the blackbody contribution to the order of 104 photoevents/sec. The instruments were thus able to identify coherent laser light contributions of 3 x 10 4 photoevents/sec within the blackbody spectrum, which is a situation that Optical SETI [Drake, 1961; Dyson, 1960; Forgan, 2014; Korpela et al., 2011; Merali, 2015; Sagan & Drake, 1975; Townes, 1983] may have to identify. The final scenario tested was to identify the laser light at 513.8 nm that has been Doppler broadened by a suspension of mono-dispersive microspheres [Dravins & Lagadec, 2014; Dravins et al., 2015]. We found that g(2)(0) = 1.227 +/- 0.005 and determined the coherence time of the broadened laser signal to be tauc = 44 +/- 2 ns, corresponding to a linewidth of about 23MHz which is comparable to the predicted linewidth values for natural lasers [Dravins & Germana, 2008; Griest et al., 2010; Johansson & Letokhov, 2005; Roche et al., 2012; Strelnitski et al., 1995; Taylor, 1983; Tellis & Marcy, 2015]. These results suggest that the narrowband spectral filtering technique developed in this thesis may provide a useful tool for revisiting intensity correlation measurements in astronomy again.

SGR 1822-1606: Constant Spin Period

NASA Astrophysics Data System (ADS)

Serim, M.; Baykal, A.; Inam, S. C.

2011-08-01

We have analyzed light curve of the new source SGR 1822-1606 (Cummings et al. GCN 12159) using the real time data of RXTE observations. We have extracted light curve for 11 pointings with a time span of about 20 days and employed pulse timing analysis using the harmonic representation of pulses. Using the cross correlation of harmonic representation of pulses, we have obtained pulse arrival times.

Interfacing Whispering-Gallery Microresonators and Free Space Light With Cavity Enhanced Rayleigh Scattering

DTIC Science & Technology

2014-09-17

in deformed silica microspheres via free-space evanescent excitation. Optics Express 15, 16471–16477 (2007). 20. Peng, B. et al. Parity - time symmetric ...devices utilizing the concepts of parity - time symmetry20. Despite their great promises for photonic technologies, coupling light into and from WGMRs is...setup used in the experiments is depicted in Fig. 1b. It consists of a tunable external cavity laser and a fiber lens as the free-space light source

Performance optimization of a bendable parabolic cylinder collimating X-ray mirror for the ALS micro-XAS beamline 10.3.2

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

Yashchuk, Valeriy V.; Morrison, Gregory Y.; Marcus, Matthew A.

The Advanced Light Source (ALS) beamline (BL) 10.3.2 is an apparatus for X-ray microprobe spectroscopy and diffraction experiments, operating in the energy range 2.4–17 keV. The performance of the beamline, namely the spatial and energy resolutions of the measurements, depends significantly on the collimation quality of light incident on the monochromator. In the BL 10.3.2 end-station, the synchrotron source is imaged 1:1 onto a set of roll slits which form a virtual source. The light from this source is collimated in the vertical direction by a bendable parabolic cylinder mirror. Details are presented of the mirror design, which allows formore » precision assembly, alignment and shaping of the mirror, as well as for extending of the mirror operating lifetime by a factor of ~10. Assembly, mirror optimal shaping and preliminary alignment were performed ex situ in the ALS X-ray Optics Laboratory (XROL). Using an original method for optimal ex situ characterization and setting of bendable X-ray optics developed at the XROL, a root-mean-square (RMS) residual surface slope error of 0.31 µrad with respect to the desired parabola, and an RMS residual height error of less than 3 nm were achieved. Once in place at the beamline, deviations from the designed optical geometry ( e.g. due to the tolerances for setting the distance to the virtual source, the grazing incidence angle, the transverse position) and/or mirror shape ( e.g. due to a heat load deformation) may appear. Due to the errors, on installation the energy spread from the monochromator is typically a few electron-volts. Here, a new technique developed and successfully implemented for at-wavelength ( in situ) fine optimal tuning of the mirror, enabling us to reduce the collimation-induced energy spread to ~0.05 eV, is described.« less

Performance optimization of a bendable parabolic cylinder collimating X-ray mirror for the ALS micro-XAS beamline 10.3.2

PubMed Central

Yashchuk, Valeriy V.; Morrison, Gregory Y.; Marcus, Matthew A.; Domning, Edward E.; Merthe, Daniel J.; Salmassi, Farhad; Smith, Brian V.

2015-01-01

The Advanced Light Source (ALS) beamline (BL) 10.3.2 is an apparatus for X-ray microprobe spectroscopy and diffraction experiments, operating in the energy range 2.4–17 keV. The performance of the beamline, namely the spatial and energy resolutions of the measurements, depends significantly on the collimation quality of light incident on the monochromator. In the BL 10.3.2 end-station, the synchrotron source is imaged 1:1 onto a set of roll slits which form a virtual source. The light from this source is collimated in the vertical direction by a bendable parabolic cylinder mirror. Details are presented of the mirror design, which allows for precision assembly, alignment and shaping of the mirror, as well as for extending of the mirror operating lifetime by a factor of ∼10. Assembly, mirror optimal shaping and preliminary alignment were performed ex situ in the ALS X-ray Optics Laboratory (XROL). Using an original method for optimal ex situ characterization and setting of bendable X-ray optics developed at the XROL, a root-mean-square (RMS) residual surface slope error of 0.31 µrad with respect to the desired parabola, and an RMS residual height error of less than 3 nm were achieved. Once in place at the beamline, deviations from the designed optical geometry (e.g. due to the tolerances for setting the distance to the virtual source, the grazing incidence angle, the transverse position) and/or mirror shape (e.g. due to a heat load deformation) may appear. Due to the errors, on installation the energy spread from the monochromator is typically a few electron-volts. Here, a new technique developed and successfully implemented for at-wavelength (in situ) fine optimal tuning of the mirror, enabling us to reduce the collimation-induced energy spread to ∼0.05 eV, is described. PMID:25931083

Performance optimization of a bendable parabolic cylinder collimating X-ray mirror for the ALS micro-XAS beamline 10.3.2

DOE PAGES

Yashchuk, Valeriy V.; Morrison, Gregory Y.; Marcus, Matthew A.; ...

2015-04-08

The Advanced Light Source (ALS) beamline (BL) 10.3.2 is an apparatus for X-ray microprobe spectroscopy and diffraction experiments, operating in the energy range 2.4–17 keV. The performance of the beamline, namely the spatial and energy resolutions of the measurements, depends significantly on the collimation quality of light incident on the monochromator. In the BL 10.3.2 end-station, the synchrotron source is imaged 1:1 onto a set of roll slits which form a virtual source. The light from this source is collimated in the vertical direction by a bendable parabolic cylinder mirror. Details are presented of the mirror design, which allows formore » precision assembly, alignment and shaping of the mirror, as well as for extending of the mirror operating lifetime by a factor of ~10. Assembly, mirror optimal shaping and preliminary alignment were performed ex situ in the ALS X-ray Optics Laboratory (XROL). Using an original method for optimal ex situ characterization and setting of bendable X-ray optics developed at the XROL, a root-mean-square (RMS) residual surface slope error of 0.31 µrad with respect to the desired parabola, and an RMS residual height error of less than 3 nm were achieved. Once in place at the beamline, deviations from the designed optical geometry ( e.g. due to the tolerances for setting the distance to the virtual source, the grazing incidence angle, the transverse position) and/or mirror shape ( e.g. due to a heat load deformation) may appear. Due to the errors, on installation the energy spread from the monochromator is typically a few electron-volts. Here, a new technique developed and successfully implemented for at-wavelength ( in situ) fine optimal tuning of the mirror, enabling us to reduce the collimation-induced energy spread to ~0.05 eV, is described.« less

Noise reduction efforts for the ALS infrared beamlines

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

Scarvie, Tom; Andresen, Nord; Baptiste, Ken

2003-08-10

The quality of infrared microscopy and spectroscopy data collected at synchrotron based sources is strongly dependent on signal-to-noise. We have successfully identified and suppressed several noise sources affecting Beamlines 1.4.2, 1.4.3, and 1.4.4 at the Advanced Light Source (ALS), resulting in a significant increase in the quality of FTIR spectra obtained. In this paper, we present our methods of noise source analysis, the negative effect of noise on the infrared beam quality, and the techniques used to reduce the noise. These include reducing the phase noise in the storage ring radio-frequency (RF) system, installing an active mirror feedback system, analyzingmore » and changing physical mounts to better isolate portions of the beamline optics from low-frequency environmental noise, and modifying the input signals to the main ALS RF system. We also discuss the relationship between electron beam energy oscillations at a point of dispersion and infrared beamline noise.« less

Noise Reduction Efforts for the ALS Infrared Beamlines

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

Scarvie, Tom; Andresen, Nord; Baptiste, Ken

2004-05-12

The quality of infrared microscopy and spectroscopy data collected at synchrotron based sources is strongly dependent on signal-to-noise. We have successfully identified and suppressed several noise sources affecting Beamlines 1.4.2, 1.4.3, and 1.4.4 at the Advanced Light Source (ALS), resulting in a significant increase in the quality of FTIR spectra obtained. In this paper, we present our methods of noise source analysis, the negative effect of noise on the infrared beam quality, and the techniques used to reduce the noise. These include reducing the phase noise in the storage ring radio-frequency (RF) system, installing an active mirror feedback system, analyzingmore » and changing physical mounts to better isolate portions of the beamline optics from low-frequency environmental noise, and modifying the input signals to the main ALS RF system. We also discuss the relationship between electron beam energy oscillations at a point of dispersion and infrared beamline noise.« less

Phosphor blends for high-CRI fluorescent lamps

DOEpatents

Setlur, Anant Achyut [Niskayuna, NY; Srivastava, Alok Mani [Niskayuna, NY; Comanzo, Holly Ann [Niskayuna, NY; Manivannan, Venkatesan [Clifton Park, NY; Beers, William Winder [Chesterland, OH; Toth, Katalin [Pomaz, HU; Balazs, Laszlo D [Budapest, HU

2008-06-24

A phosphor blend comprises at least two phosphors each selected from one of the groups of phosphors that absorb UV electromagnetic radiation and emit in a region of visible light. The phosphor blend can be applied to a discharge gas radiation source to produce light sources having high color rendering index. A phosphor blend is advantageously includes the phosphor (Tb,Y,LuLa,Gd).sub.x(Al,Ga).sub.yO.sub.12:Ce.sup.3+, wherein x is in the range from about 2.8 to and including 3 and y is in the range from about 4 to and including 5.

Conjugation of both on-axis and off-axis light in Nipkow disk confocal microscope to increase availability of incoherent light source.

PubMed

Saito, Kenta; Arai, Yoshiyuki; Zhang, Jize; Kobayashi, Kentaro; Tani, Tomomi; Nagai, Takeharu

2011-01-01

Laser-scanning confocal microscopy has been employed for exploring structures at subcellular, cellular and tissue level in three dimensions. To acquire the confocal image, a coherent light source, such as laser, is generally required in conventional single-point scanning microscopy. The illuminating beam must be focused onto a small spot with diffraction-limited size, and this determines the spatial resolution of the microscopy system. In contrast, multipoint scanning confocal microscopy using a Nipkow disk enables the use of an incoherent light source. We previously demonstrated successful application of a 100 W mercury arc lamp as a light source for the Yokogawa confocal scanner unit in which a microlens array was coupled with a Nipkow disk to focus the collimated incident light onto a pinhole (Saito et al., Cell Struct. Funct., 33: 133-141, 2008). However, transmission efficiency of incident light through the pinhole array was low because off-axis light, the major component of the incident light, was blocked by the non-aperture area of the disk. To improve transmission efficiency, we propose an optical system in which off-axis light is able to be transmitted through pinholes surrounding the pinhole located on the optical axis of the collimator lens. This optical system facilitates the use of not only the on-axis but also the off-axis light such that the available incident light is considerably improved. As a result, we apply the proposed system to high-speed confocal and multicolor imaging both with a satisfactory signal-to-noise ratio.

The JLab high power ERL light source

NASA Astrophysics Data System (ADS)

Neil, G. R.; Behre, C.; Benson, S. V.; Bevins, M.; Biallas, G.; Boyce, J.; Coleman, J.; Dillon-Townes, L. A.; Douglas, D.; Dylla, H. F.; Evans, R.; Grippo, A.; Gruber, D.; Gubeli, J.; Hardy, D.; Hernandez-Garcia, C.; Jordan, K.; Kelley, M. J.; Merminga, L.; Mammosser, J.; Moore, W.; Nishimori, N.; Pozdeyev, E.; Preble, J.; Rimmer, R.; Shinn, M.; Siggins, T.; Tennant, C.; Walker, R.; Williams, G. P.; Zhang, S.

2006-02-01

A new THz/IR/UV photon source at Jefferson Lab is the first of a new generation of light sources based on an Energy-Recovered, (superconducting) Linac (ERL). The machine has a 160 MeV electron beam and an average current of 10 mA in 75 MHz repetition rate hundred femtosecond bunches. These electron bunches pass through a magnetic chicane and therefore emit synchrotron radiation. For wavelengths longer than the electron bunch the electrons radiate coherently a broadband THz ˜ half cycle pulse whose average brightness is >5 orders of magnitude higher than synchrotron IR sources. Previous measurements showed 20 W of average power extracted [Carr, et al., Nature 420 (2002) 153]. The new facility offers simultaneous synchrotron light from the visible through the FIR along with broadband THz production of 100 fs pulses with >200 W of average power. The FELs also provide record-breaking laser power [Neil, et al., Phys. Rev. Lett. 84 (2000) 662]: up to 10 kW of average power in the IR from 1 to 14 μm in 400 fs pulses at up to 74.85 MHz repetition rates and soon will produce similar pulses of 300-1000 nm light at up to 3 kW of average power from the UV FEL. These ultrashort pulses are ideal for maximizing the interaction with material surfaces. The optical beams are Gaussian with nearly perfect beam quality. See www.jlab.org/FEL for details of the operating characteristics; a wide variety of pulse train configurations are feasible from 10 ms long at high repetition rates to continuous operation. The THz and IR system has been commissioned. The UV system is to follow in 2005. The light is transported to user laboratories for basic and applied research. Additional lasers synchronized to the FEL are also available. Past activities have included production of carbon nanotubes, studies of vibrational relaxation of interstitial hydrogen in silicon, pulsed laser deposition and ablation, nitriding of metals, and energy flow in proteins. This paper will present the status of the system and discuss some of the discoveries we have made concerning the physics performance, design optimization, and operational limitations of such a first generation high power ERL light source.

High-luminance LEDs replace incandescent lamps in new applications

NASA Astrophysics Data System (ADS)

Evans, David L.

1997-04-01

The advent of high luminance AlInGaP and InGaN LED technologies has prompted the use of LED devices in new applications formally illuminated by incandescent lamps. The luminous efficiencies of these new LED technologies equals or exceeds that attainable with incandescent sources, with reliability factors that far exceed those of incandescent sources. The need for a highly efficient, dependable, and cost effective replacement for incandescent lamps is being fulfilled with high luminance LED lamps. This paper briefly described some of the new applications incorporating high luminance LED lamps, traffic signals and roadway signs for traffic management, automotive exterior lighting, active matrix and full color displays for commercial advertising, and commercial aircraft panel lighting and military aircraft NVG compatible lighting.

Development of a high performance surface slope measuring system for two-dimensional mapping of x-ray optics

NASA Astrophysics Data System (ADS)

Lacey, Ian; Adam, Jérôme; Centers, Gary P.; Gevorkyan, Gevork S.; Nikitin, Sergey M.; Smith, Brian V.; Yashchuk, Valeriy V.

2017-09-01

The research and development work on the Advanced Light Source (ALS) upgrade to a diffraction limited storage ring light source, ALS-U, has brought to focus the need for near-perfect x-ray optics, capable of delivering light to experiments without significant degradation of brightness and coherence. The desired surface quality is characterized with residual (after subtraction of an ideal shape) surface slope and height errors of <50-100 nrad (rms) and <1-2 nm (rms), respectively. The ex-situ metrology that supports the optimal usage of the optics at the beamlines has to offer even higher measurement accuracy. At the ALS X-Ray Optics Laboratory, we are developing a new surface slope profiler, the Optical Surface Measuring System (OSMS), capable of two-dimensional (2D) surface-slope metrology at an absolute accuracy below the above optical specification. In this article we provide the results of comprehensive characterization of the key elements of the OSMS, a NOM-like high-precision granite gantry system with air-bearing translation and a custom-made precision air-bearing stage for tilting and flipping the surface under test. We show that the high performance of the gantry system allows implementing an original scanning mode for 2D mapping. We demonstrate the efficiency of the developed 2D mapping via comparison with 1D slope measurements performed with the same hyperbolic test mirror using the ALS developmental long trace profiler. The details of the OSMS design and the developed measuring techniques are also provided.

Photon stimulated desorption from oxidized Al(110). [Surface hydroxyls

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

Johnson, E.D.; Garrett, R.F.; Knotek, M.L.

1987-01-01

We have studied oxide films on Al(110) by photon stimulated desorption (PSD) on the Bell Labs U4 PGM at the National Synchrotron Light Source. Utilizing a time of flight technique we have obtained ion energy distribution (IED) and relative ion yield (RIY) data at the Al 2p and O 1s edges for oxides prepared at various temperatures. These initial studies suggest that different sites for the surface hydroxyls exist, that they can be selectively prepared, and examined by PSD. 15 refs., 9 figs.

Note: A portable, light-emitting diode-based ruby fluorescence spectrometer for high-pressure calibration

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

Feng Yejun

2011-04-15

Ruby (Al{sub 2}O{sub 3}, with {approx}0.5 wt. % Cr doping) is one of the most widely used manometers at the giga-Pascal scale. Traditionally, its fluorescence is excited with intense laser sources. Here, I present a simple, robust, and portable design that employs light-emitting diodes (LEDs) instead. This LED-based system is safer in comparison with laser-based ones.

A Strong X-ray Flare in TeV-detected blazar 1ES 1959+650

NASA Astrophysics Data System (ADS)

Kapanadze, Bidzina

2017-06-01

Since 2015 August, the nearby TeV-detected HBL source 1ES 1959+650 (z=0.048) is in a phase of enhanced X-ray activity compared to the previous years (Kapanadze et al. 2016, MNRAS, 461, L26; ATel #8014, #8289, #8342, #8468, #9121, #9205, #9694, #9949, #10430 and http://www.swift.psu.edu/monitoring/source.php?source=1ES1959+650 for the historical 0.3-10 keV light curve).

Another X-ray Flare in TeV-detected blazar 1ES 1959+650

NASA Astrophysics Data System (ADS)

Kapanadze, Bidzina

2017-05-01

Since 2015 August, the nearby TeV-detected HBL source 1ES 1959+650 (z=0.048) is in a phase of enhanced X-ray activity compared to the previous years (Kapanadze et al. 2016, MNRAS, 461, L26; ATel #8014, #8289, #8342, #8468, #9121, #9205, #9694, #9949, and http://www.swift.psu.edu/monitoring/source.php?source=1ES1959+650 for the historical 0.3-10 keV light curve).

Superbend era begins swiftly at the ALS

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

Robinson, Art; Tamura, Lori

2001-11-29

The successful installation and commissioning of high-field superconducting bend magnets (superbends) in three curved sectors of ALS storage ring was the first time the magnet lattice of an operating synchrotron light source has been retrofitted in this fundamental way. As a result, the ALS now offers an expanded spectral range well into the hard x-ray region without compromising either the number of undulators or their high brightness in the soft x-ray region for which the ALS design was originally optimized. In sum, when the superbend-enhanced ALS started up for user operations in October 2001, it marked the beginning of amore » new era in its history.« less

12th Annual ALS Users' Association Meeting

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

Robinson, Arthur L.

1999-12-17

Science took the front seat as 219 Advanced Light Source (ALS) users and staff gathered on Monday and Tuesday, October 18 and 19 for the twelfth annual users' meeting. The bulk of the meeting was dedicated to reports on science at the ALS. Packed into two busy days were 31 invited oral presentations and 80 submitted poster presentations, as well as time to visit 24 vendor booths. The oral sessions were dedicated to environmental science, chemical dynamics, biosciences, magnetic materials, and atomic and molecular science. In addition, there was an ALS highlights session that emphasized new results and a sessionmore » comprising highlights from the young scientists who will carry the ALS into the future.« less

NDIR gas sensing using high performance AlInSb mid-infrared LEDs as light source

NASA Astrophysics Data System (ADS)

Camargo, E. G.; Goda, Y.; Morohara, O.; Fujita, H.; Geka, H.; Ueno, K.; Shibata, Y.; Kuze, N.

2017-08-01

In this paper, we report the performance of room temperature operated mid-infrared light emitting diode (LED) with an InSb buffer layer and AlInSb active/barrier layers, which showed to be suitable for non-dispersive infrared (NDIR) gas sensing. Characterization of the LED was performed and we found that good carrier confinement and crystalline quality was responsible for its high performance. High efficiency light extraction was obtained by adopting backside emission architecture together with surface roughening treatment and TiO2 anti-reflection coating. The fabricated AlInSb LED showed 75% higher power conversion efficiency when compared with a commercially available device. The developed LED, together with a commercially available infrared (IR) detector equipped with band-pass optical filter (AK9710, manufactured by Asahi Kasei Microdevices) were coupled into a mirror system forming a light path length of 80 mm, which was tested for CO2 gas sensing. For a non-absorbing environment, sensor output of 8 nA was obtained by driving the LED with peak current of 100 mA and, by exposing the system at CO2 concentration of 1000 ppm signal reduction due to absorbance around 12% was obtained.

RXTE Detection of the Spin Period of Swift J1822.3-1606

NASA Astrophysics Data System (ADS)

Gogus, Ersin; Kouveliotou, Chryssa; Strohmayer, Tod

2011-07-01

RXTE/PCA observed the new source, Swift J1822.3-1606 (Cummings et al. GCN Circ. 12159) on 2011 July 16, for 6.7 ks. We performed a timing analysis on the barycentered data and detected a coherent pulsation at 0.1185149(2) Hz corresponding to 8.4377585 s. Pulsations are clearly visible in the PCA light curve. The peak-to-peak pulsed amplitude in the 2-10 keV band is 0.41. This pulsed fraction is highly unlikely from an SGR source, and very reminiscent of the outburst onset of Swift J1626.6-5156 (Palmer et al.

CTC Sentinel. Volume 7, Issue 2, February 2014

DTIC Science & Technology

2014-02-01

restaurants and hotels. It is the principal source of insecurity in most of Somalia, including the northern state of Puntland. Penetrating and...outdoor restaurant at Nairobi’s Jomo Kenyatta International Airport. See “Four Somalis Charged over Kenya ‘Light Bulb’ Airport Attack,” Agence...it was commonly known as “Boko Haram.” Shekau pledged loyalty to “the amir of al-Qa`ida in the Islamic Maghreb,” Usama bin Ladin, Ayman al

X-Ray Source Heights in a Solar Flare: Thick-Target Versus Thermal Conduction Front Heating

NASA Technical Reports Server (NTRS)

Reep, J. W.; Bradshaw, S. J.; Holman, G. D.

2016-01-01

Observations of solar flares with RHESSI have shown X-ray sources traveling along flaring loops, from the corona down to the chromosphere and back up. The 2002 November 28 C1.1 flare, first observed with RHESSI by Sui et al. and quantitatively analyzed by O'Flannagain et al., very clearly shows this behavior. By employing numerical experiments, we use these observations of X-ray source height motions as a constraint to distinguish between heating due to a non-thermal electron beam and in situ energy deposition in the corona. We find that both heating scenarios can reproduce the observed light curves, but our results favor non-thermal heating. In situ heating is inconsistent with the observed X-ray source morphology and always gives a height dispersion with photon energy opposite to what is observed.

Deep Ultraviolet Light Emitters Based on (Al,Ga)N/GaN Semiconductor Heterostructures

NASA Astrophysics Data System (ADS)

Liang, Yu-Han

Deep ultraviolet (UV) light sources are useful in a number of applications that include sterilization, medical diagnostics, as well as chemical and biological identification. However, state-of-the-art deep UV light-emitting diodes and lasers made from semiconductors still suffer from low external quantum efficiency and low output powers. These limitations make them costly and ineffective in a wide range of applications. Deep UV sources such as lasers that currently exist are prohibitively bulky, complicated, and expensive. This is typically because they are constituted of an assemblage of two to three other lasers in tandem to facilitate sequential harmonic generation that ultimately results in the desired deep UV wavelength. For semiconductor-based deep UV sources, the most challenging difficulty has been finding ways to optimally dope the (Al,Ga)N/GaN heterostructures essential for UV-C light sources. It has proven to be very difficult to achieve high free carrier concentrations and low resistivities in high-aluminum-containing III-nitrides. As a result, p-type doped aluminum-free III-nitrides are employed as the p-type contact layers in UV light-emitting diode structures. However, because of impedance-mismatch issues, light extraction from the device and consequently the overall external quantum efficiency is drastically reduced. This problem is compounded with high losses and low gain when one tries to make UV nitride lasers. In this thesis, we provide a robust and reproducible approach to resolving most of these challenges. By using a liquid-metal-enabled growth mode in a plasma-assisted molecular beam epitaxy process, we show that highly-doped aluminum containing III-nitride films can be achieved. This growth mode is driven by kinetics. Using this approach, we have been able to achieve extremely high p-type and n-type doping in (Al,Ga)N films with high aluminum content. By incorporating a very high density of Mg atoms in (Al,Ga)N films, we have been able to show, by temperature-dependent photoluminescence, that the activation energy of the acceptors is substantially lower, thus allowing a higher hole concentration than usual to be available for conduction. It is believed that the lower activation energy is a result of an impurity band tail induced by the high Mg concentration. The successful p-type doping of high aluminum-content (Al,Ga)N has allowed us to demonstrate operation of deep ultraviolet LEDs emitting at 274 nm. This achievement paves the way for making lasers that emit in the UV-C region of the spectrum. In this thesis, we performed preliminary work on using our structures to make UV-C lasers based on photonic crystal nanocavity structures. The nanocavity laser structures show that the threshold optical pumping power necessary to reach lasing is much lower than in conventional edge-emitting lasers. Furthermore, the photonic crystal nanocavity structure has a small mode volume and does not need mirrors for optical feedback. These advantages significantly reduce material loss and eliminate mirror loss. This structure therefore potentially opens the door to achieving efficient and compact lasers in the UV-C region of the spectrum.

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

Andreeva, E V; Il'ichenko, S N; Kostin, Yu O

Quantum-well superluminescent diodes (SLD) with extremely thin active (AlGa)As and (InGa)As layers and centre wavelengths about 810, 840, 860 and 880 nm are experimentally studied. Their emission spectrum possesses the shape close to Gaussian, its FWHM being 30 – 60 nm depending on the length of the active channel and the level of pumping. Under cw injection, the output power of light-emitting modules based on such SLDs can amount to 1.0 – 25 mW at the output of a single-mode fibre. It is demonstrated that the operation lifetime of these devices exceeds 30000 hours. Based on the light-emitting modules themore » prototypes of combined BroadLighter series light sources are implemented having a bell-shaped spectrum with the width up to 100 nm. (optical radiation sources)« less

A closed-loop photon beam control study for the Advanced Light Source

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

Portmann, G.; Bengtsson, J.

1993-05-01

The third generation Advanced Light Source (ALS) will produce extremely bright photon beams using undulators and wigglers. In order to position the photon beams accurate to the micron level, a closed-loop feedback system is being developed. Using photon position monitors and dipole corrector magnets, a closed-loop system can automatically compensate for modeling uncertainties and exogenous disturbances. The following paper will present a dynamics model for the perturbations of the closed orbit of the electron beam in the ALS storage ring including the vacuum chamber magnetic field penetration effects. Using this reference model, two closed-loop feedback algorithms will be compared --more » a classical PI controller and a two degree-of-freedom approach. The two degree-of-freedom method provides superior disturbance rejection while maintaining the desired performance goals. Both methods will address the need to gain schedule the controller due to the time varying dynamics introduced by changing field strengths when scanning the insertion devices.« less

Spitzer - Hot & Colorful Student Activities

NASA Astrophysics Data System (ADS)

McDonald, D.; Rebull, L. M.; DeWolf, C.; Guastella, P.; Johnson, C. H.; Schaefers, J.; Spuck, T.; McDonald, J. G., III; DeWolf, T.; Brock, S.; Boerma, J.; Bemis, G.; Paulsen, K.; Yueh, N.; Peter, A.; Wassmer, W.; Haber, R.; Scaramucci, A.; Butchart, J.; Holcomb, A.; Karns, B.; Kennedy, S.; Siegel, R.; Weiser, S.

2009-01-01

In this poster, we present the results of several activities developed for the general science student to explore infrared light. The first activity involved measuring infrared radiation using an updated version of Newton's experiment of splitting white light and finding IR radiation. The second used Leslie's cube to allow students to observe different radiators, while the third used a modern infrared thermometer to measure and identify IR sources in an enclosed box. The last activity involved students making false-color images from narrow-band filter images from data sets from Spitzer Space Telescope, STScI Digitized Sky Survey and other sources. Using computer programs like Adobe Photoshop and free software such as ds9, Spot and Leopard, poster-like images were created by the students. This research is funded by the Spitzer Science Center (SSC) and the National Optical Astronomy Observatory (NOAO). Please see our companion poster, Johnson et al., on the science aspect of this program, and another poster on the educational aspects, Guastella et al.

ABSOLUTE BUNCH LENGTH MEASUREMENTS AT THE ALS BY INCOHERENTSYNCHROTRON RADIATION FLUCTUATION ANALYSIS

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

Sannibale, Fernando; Zolotorev, Max S.; Filippetto, Daniele

2007-06-22

By analysing the pulse to pulse intensity fluctuations ofthe radiation emitted by a charge particle in the incoherent part of thespectrum, it is possible to extract information about the spatialdistribution of the beam. At the Advanced Light Source (ALS) of theLawrence Berkeley National Laboratory, we have developed and tested asimple scheme based on this principle that allows for the absolutemeasurement of the bunch length. A description of the method and theexperimental results are presented.

A laser based frequency modulated NL-OSL phenomenon

NASA Astrophysics Data System (ADS)

Mishra, D. R.; Bishnoi, A. S.; Soni, Anuj; Rawat, N. S.; Bhatt, B. C.; Kulkarni, M. S.; Babu, D. A. R.

2015-01-01

The detailed theoretical and experimental approach to novel technique of pulse frequency modulated stimulation (PFMS) method has been described for NL-OSL phenomenon. This method involved pulsed frequency modulation with respect to time for fixed pulse width of 532 nm continuous wave (CW)-laser light. The linearly modulated (LM)-, non-linearly (NL)-stimulation profiles have been generated using fast electromagnetic optical shutter. The PFMS parameters have been determined for present experimental setup. The PFMS based LM-, NL-OSL studies have been carried out on dosimetry grade single crystal α-Al2O3:C. The photo ionization cross section of α-Al2O3:C has been found to be ∼9.97 × 10-19 cm2 for 532 nm laser light using PFMS LM-OSL studies under assumption of first order of kinetic. This method of PFMS is found to be a potential alternative to generate different stimulation profiles using CW-light sources.

Deep-UV sensors based on SAW oscillators using low-temperature-grown AlN films on sapphires.

PubMed

Laksana, Chipta; Chen, Meei-Ru; Liang, Yen; Tzou, An-Jyeg; Kao, Hui-Ling; Jeng, Erik; Chen, Jyh; Chen, Hou-Guang; Jian, Sheng-Rui

2011-08-01

High-quality epitaxial AlN films were deposited on sapphire substrates at low growth temperature using a helicon sputtering system. SAW filters fabricated on the AlN films exhibited excellent characteristics, with center frequency of 354.2 MHz, which corresponds to a phase velocity of 5667 m/s. An oscillator fabricated using AlN-based SAW devices is presented and applied to deep-UV light detection. A frequency downshift of about 43 KHz was observed when the surface of SAW device was illuminated by a UV source with dominant wavelength of around 200 nm. The results indicate the feasibility of developing remote sensors for deep-UV measurement using AlN-based SAW oscillators.

Physics Notes

ERIC Educational Resources Information Center

School Science Review, 1972

1972-01-01

Short articles describe the production, photography, and analysis of diffraction patterns using a small laser, a technique for measuring electrical resistance without a standard resistor, a demonstration of a thermocouple effect in a galvanometer with a built-in light source, and a common error in deriving the expression for centripetal force. (AL)

Compression and Associated Properties of Boron Carbide

DTIC Science & Technology

2008-12-01

of Brookhaven National Laboratory ( BNL ) with the light extracted from the x-ray source in a method previously described (Liu et al., 2002).. A...are sharper and more intense relative to as received material. ACKNOWLEDGMENTS Thanks are due to Dr. Jingzhu Hu and Dr. Zhenxian Liu of BNL

III-N light emitting diodes fabricated using RF nitrogen gas source MBE

NASA Astrophysics Data System (ADS)

Van Hove, J. M.; Carpenter, G.; Nelson, E.; Wowchak, A.; Chow, P. P.

1996-07-01

Homo- and heterojunction III-N light emitting diodes using RF atomic nitrogen plasma molecular beam epitaxy have been grown. GaN films deposited on sapphire using this growth technique exhibited an extremely sharp X-ray diffraction with a full width half maximum of 112 arc sec. p-type doping of the nitride films was done with elemental Mg and resulted in as-grown p-type material with resistivities as low as 2 Ω · cm. Both homo- and heterojunction LEDs showed clear rectification. Emission from the GaN homojunction deposited on n-type SiC was peaked at 410 nm while the AlGaNGaN(Zn)AlGaN double heterojunction LEDs emission was centered about 520 nm.

The BATSE Earth Occultation Catalog of Low Energy Gamma-Ray Sources

NASA Technical Reports Server (NTRS)

Harmon, B. A.; Wilson-Hodge, C. A.; Fishman, G. J.; Paciesas, W. S.; Zhang, S. N.; Finger, M. H.; Connaughton, V.; Koshut, T. M.; Henze, W.; McCollough, M. L.

2004-01-01

The Burst and Transient Source Experiment (BATSE),aboard the COmptOn Gamma Ray Observatory (CGRO), provided a record of the hard X-ray/low energy gamma ray sky between April 1991 and June 2000. During that time, a catalog of known sources was derived from existing catalogs such as HEAO A-4 (Levine et al. 19841, as well as new transient sources discovered with RATSE and other X-ray monitors operating in the CGRO era. The Earth Occultation Technique (Harmon et al. 2001, astro-ph/0109069) was used to monitor a combination of these sources, mostly galactic, totaling about 175 objects. The catalog will present the global properties of these sources and their probability of detection (>lO mCrab, 20-100 keV) with BATSE. Systematic errors due to unknown sources or background components are included. Cursory analyses to search for new transients (35-80 mCrab in the 20-100 keV band) and super-orbital periods in known binary sources are also presented. Whole mission light curves and associated data production/analysis tools are being delivered to the HEASARC for public use.

Absolute Bunch Length Measurements at the ALS by Incoherent Synchrotron Radiation Fluctuation Analysis

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

Filippetto, D.; /Frascati; Sannibale, F.

2008-01-24

By analyzing the pulse to pulse intensity fluctuations of the radiation emitted by a charge particle in the incoherent part of the spectrum, it is possible to extract information about the spatial distribution of the beam. At the Advanced Light Source (ALS) of the Lawrence Berkeley National Laboratory, we have developed and tested a simple scheme based on this principle that allows for the absolute measurement of the bunch length. A description of the method and the experimental results are presented.

The Advanced Light Source Elliptically Polarizing Undulator

NASA Astrophysics Data System (ADS)

Marks, Steve; Cortopassi, Christopher; Devries, Jan; Hoyer, Egon; Leinbach, Robert; Minamihara, Yoshi; Padmore, Howard; Pipersky, Paul; Plate, Dave; Schlueter, Ross; Young, Anthony

1997-05-01

An elliptically polarizing undulator for the Advanced Light Source has been designed and is currently under construction. The magnetic design is a four quadrant pure permanent magnet structure featuring moveable magnets to correct phase errors and on axis field integrals. The device is designed with a 5.0 cm period and will produce variably polarized light of any ellipticity, including pure circular and linear. The spectral range at 1.9 GeV for typical elliptical polarization with a degree of circular polarization greater than 0.8 will be from 100 eV to 1500 eV, using the third and fifth spectral harmonics. The device will be switchabe between left and right circular modes at a frequency of up to 0.1 Hz. The 1.95 m long overall length will allow two such devices in a single ALS straight sector.

Synchrotron X-ray micro-tomography at the Advanced Light Source: Developments in high-temperature in-situ mechanical testing

NASA Astrophysics Data System (ADS)

Barnard, Harold S.; MacDowell, A. A.; Parkinson, D. Y.; Mandal, P.; Czabaj, M.; Gao, Y.; Maillet, E.; Blank, B.; Larson, N. M.; Ritchie, R. O.; Gludovatz, B.; Acevedo, C.; Liu, D.

2017-06-01

At the Advanced Light Source (ALS), Beamline 8.3.2 performs hard X-ray micro-tomography under conditions of high temperature, pressure, mechanical loading, and other realistic conditions using environmental test cells. With scan times of 10s-100s of seconds, the microstructural evolution of materials can be directly observed over multiple time steps spanning prescribed changes in the sample environment. This capability enables in-situ quasi-static mechanical testing of materials. We present an overview of our in-situ mechanical testing capabilities and recent hardware developments that enable flexural testing at high temperature and in combination with acoustic emission analysis.

The infrared imaging spectrograph (IRIS) for TMT: overview of innovative science programs

NASA Astrophysics Data System (ADS)

Wright, Shelley A.; Larkin, James E.; Moore, Anna M.; Do, Tuan; Simard, Luc; Adamkovics, Maté; Armus, Lee; Barth, Aaron J.; Barton, Elizabeth; Boyce, Hope; Cooke, Jeffrey; Cote, Patrick; Davidge, Timothy; Ellerbroek, Brent; Ghez, Andrea M.; Liu, Michael C.; Lu, Jessica R.; Macintosh, Bruce A.; Mao, Shude; Marois, Christian; Schoeck, Matthias; Suzuki, Ryuji; Tan, Jonathan C.; Treu, Tommaso; Wang, Lianqi; Weiss, Jason

2014-07-01

IRIS (InfraRed Imaging Spectrograph) is a first light near-infrared diffraction limited imager and integral field spectrograph being designed for the future Thirty Meter Telescope (TMT). IRIS is optimized to perform astronomical studies across a significant fraction of cosmic time, from our Solar System to distant newly formed galaxies (Barton et al. [1]). We present a selection of the innovative science cases that are unique to IRIS in the era of upcoming space and ground-based telescopes. We focus on integral field spectroscopy of directly imaged exoplanet atmospheres, probing fundamental physics in the Galactic Center, measuring 104 to 1010 M supermassive black hole masses, resolved spectroscopy of young star-forming galaxies (1 < z < 5) and first light galaxies (6 < z < 12), and resolved spectroscopy of strong gravitational lensed sources to measure dark matter substructure. For each of these science cases we use the IRIS simulator (Wright et al. [2], Do et al. [3]) to explore IRIS capabilities. To highlight the unique IRIS capabilities, we also update the point and resolved source sensitivities for the integral field spectrograph (IFS) in all five broadband filters (Z, Y, J, H, K) for the finest spatial scale of 0.004" per spaxel. We briefly discuss future development plans for the data reduction pipeline and quicklook software for the IRIS instrument suite.

The Art of Photoelectron Spectroscopy, from Micro to Nano

NASA Astrophysics Data System (ADS)

Rotenberg, Eli

Angle-resolved photoemission spectroscopy (ARPES) was developed for the determination of the electronic bandstructure of solids. In the last 20 years, ARPES has become nearly unlimited with respect to instrumental resolution, and therefore able to illuminate more subtle electronic aspects, such as ground-state symmetry breaking and the many-body interactions (MBIs) that characterize ground states such as superconductivity. These MBIs involve exchange of momentum among electrons or with excitations such as phonons, and can therefore couple to nanoscale structures. By controlling the structure at the nanoscale, we can therefore hope to control or enhance the ground state properties of materials through nanoscale engineering. This dream has motivated the development of nanoscale ARPES (nanoARPES) machines that are now coming online worldwide. After a brief overview, I will show the latest results from the new nanoARPES endstation at the MAESTRO facility (Microscopic and Electronic Structure Observatory), a new user beamline commissioned this year at the Advanced Light Source (ALS). We achieved routine operation at spatial resolution around 120 nm, and expect improvement down to 50 nm or better. Examples will include graphene and 2D-metal-chalcogenide heterostructures. I will also discuss the prospects for dramatic improvements expected as new diffraction-limited light sources such as the ALS-U project are realized. Work performed at the Advanced Light Source is supported by the Director, Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.

Gamma-ray line emission from Al-26 produced by Wolf-Rayet stars

NASA Technical Reports Server (NTRS)

Prantzos, N.; Casse, M.; Gros, M.; Doom, C.; Arnould, M.

1985-01-01

The recent satellite observations of the 1.8 MeV line from the decay of Al-26 has given a new impetus to the study of the nucleosynthesis of Al-26. The production and ejection of Al-26 by massive mass-losing stars (Of and WR stars) is discussed in the light of recent stellar models. The longitude distribution of the Al-26 gamma ray line emission produced by the galactic collection of WR stars is derived based on various estimates of their radial distribution. This longitude profile provides: (1) a specific signature of massive stars on the background of other potential Al-26 sources, as novae, supernovae, certain red giants and possibly AGB stars; and (2) a possible tool to improve the data analysis of the HEAO 3 and SMM experiments.

Diagnostic Systems Plan for the Advanced Light Source Top-OffUpgrade

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

Barry, Walter; Chin, Mike; Robin, David

2005-05-10

The Advanced Light Source (ALS) will soon be upgraded to enable top-off operations [1], in which electrons are quasi-continuously injected to produce constant stored beam current. The upgrade is structured in two phases. First, we will upgrade our injector from 1.5 GeV to 1.9 GeV to allow full energy injection and will start top-off operations. In the second phase, we will upgrade the Booster Ring (BR) with a bunch cleaning system to allow high bunch purity top-off injection. A diagnostics upgrade will be crucial for success in both phases of the top-off project, and our plan for it is describedmore » in this paper. New booster ring diagnostics will include updated beam position monitor (BPM) electronics, a tune monitoring system, and a new scraper. Two new synchrotron light monitors and a beam stop will be added to the booster-to-storage ring transfer line (BTS), and all the existing beam current monitors along the accelerator chain will be integrated into a single injection efficiency monitoring application. A dedicated bunch purity monitor will be installed in the storage ring (SR). Together, these diagnostic upgrades will enable smooth commissioning of the full energy injector and a quick transition to high quality top-off operation at the ALS.« less

The use of serum free light chain dimerization patterns assist in the diagnosis of AL amyloidosis.

PubMed

Gatt, Moshe E; Kaplan, Batia; Yogev, Dean; Slyusarevsky, Elana; Pogrebijski, Galina; Golderman, Sizilia; Kukuy, Olga; Livneh, Avi

2018-05-16

The discrimination between benign and malignant forms of plasma cell dyscrasia (PCD) is often difficult. Free light chain monomer-dimer pattern analysis (FLC-MDPA) may assist in solving this dilemma and distinguish between AL amyloidosis and benign PCD. Serum samples of patients with AL amyloidosis and benign PCD were analysed in a blinded manner. Quantitative Western blotting was performed to estimate dimerization and clonality indices, and thereby determine the source of the tested samples, as derived either from benign or malignant PCD. The findings obtained by the FLC-MDPA were compared with the actual diagnosis. Of 37 samples from patients with active AL amyloidosis, 34 (91·9%) fulfilled dimerization criteria for diagnosis of AL amyloidosis. Of the 45 samples from patients with benign PCD, 10 (21·2%) tested falsely positive or gave an inconclusive result. Thus, the sensitivity of the analysis was 92·5% with a remarkable negative predictive value of 91·9%. In addition, of 20 patients who were in complete or very good partial remission, only one tested positive. By multivariate analysis, FLC-MDPA was the best independent marker predicting AL amyloidosis (odds ratio of 84). The FLC-MDPA offers a highly effective tool in the diagnostic assessment of patients with PCD. © 2018 John Wiley & Sons Ltd.

The Development of Ultraviolet Light Emitting Diodes on p-SiC Substrates

NASA Astrophysics Data System (ADS)

Brummer, Gordon

Ultraviolet (UV) light emitting diodes (LEDs) are promising light sources for purification, phototherapy, and resin curing applications. Currently, commercial UV LEDs are composed of AlGaN-based n-i-p junctions grown on sapphire substrates. These devices suffer from defects in the active region, inefficient p-type doping, and poor light extraction efficiency. This dissertation addresses the development of a novel UV LED device structure, grown on p-SiC substrates. In this device structure, the AlGaN-based intrinsic (i) and n-layers are grown directly on the p-type substrate, forming a p-i-n junction. The intrinsic layer (active region) is composed of an AlN buffer layer followed by three AlN/Al0.30Ga0.70N quantum wells. After the intrinsic layer, the n-layer is formed from n-type AlGaN. This device architecture addresses the deficiencies of UV LEDs on sapphire substrates while providing a vertical device geometry, reduced fabrication complexity, and improved thermal management. The device layers were grown by molecular beam epitaxy (MBE). The material properties were optimized by considering varying growth conditions and by considering the role of the layer within the device. AlN grown at 825 C and with a Ga surfactant yielded material with screw dislocation density of 1x10 7 cm-2 based on X-ray diffraction (XRD) analysis. AlGaN alloys grown in this work contained compositional inhomogeneity, as verified by high-resolution XRD, photoluminescence, and absorption measurements. Based on Stokes shift measurements, the degree of compositional inhomogeneity was correlated with the amount of excess Ga employed during growth. Compositional inhomogeneity yields carrier localizing potential fluctuations, which are advantages in light emitting device layers. Therefore, excess Ga growth conditions were used to grow AlN/Al0.30Ga0.70N quantum wells (designed using a wurtzite k.p model) with 35% internal quantum efficiency. Potential fluctuations limit the mobility of carriers and introduce sub-bandgap absorption, making them undesirable in the n-AlGaN layers. n-Al0.60Ga 0.40N grown under stoichiometric Ga flux and an In surfactant reduced the Stokes shift (compared to n-AlGaN grown without In) by 150 meV. However, even under these growth modes, some compositional inhomogeneity persisted which is speculatively attributed to the vicinal substrate. Device epitaxial layer stacks utilizing the optimum growth conditions were fabricated into prototype vertical UV LEDs which emit from 295-320 nm. In order to increase light extraction efficiency, UV distributed Bragg reflectors (DBRs) based on compositionally graded AlGaN alloys were designed using the transfer matrix method (TMM) and grown by MBE. DBRs were formed from repeated compositionally graded AlGaN alloys. This structure utilized the polarization doping and index of refraction variation of graded composition AlGaN. DBRs with square wave, sinusoidal, triangular, and sawtooth compositional profiles were realized, with reflectivity peaks over 50%, centered at 280 nm.

ALS superbend magnet performance

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

Marks, Steve; Zbasnik, John; Byrne, Warren

2001-12-10

The Lawrence Berkeley National Laboratory has been engaged in the design, construction and testing of four superconducting dipoles (Superbends) that are installed in three arcs of the Advanced Light Source (ALS), with the fourth magnet as a spare. This represents a major upgrade to the ALS providing an enhanced flux and brightness at photon energies above 10 keV. In preparation for installation, an extensive set of tests and measurements have been conducted to characterize the magnetic and cryogenic performance of the Superbends and to fiducialize them for accurate placement in the ALS storage ring. The magnets are currently installed, andmore » the storage ring is undergoing final commissioning. This paper will present the results of magnetic and cryogenic testing.« less

Color stable manganese-doped phosphors

DOEpatents

Lyons, Robert Joseph; Setlur, Anant Achyut; Deshpande, Anirundha Rajendra; Grigorov, Ljudmil Slavchev

2014-04-29

A lighting apparatus capable of emitting white light includes a semiconductor light source; and a phosphor material radiationally coupled to the light source. The phosphor material includes a color-stable Mn.sup.+4 doped phosphor prepared by a process including providing a phosphor of formula I; A.sub.x[MF.sub.y]:Mn.sup.+4 I and contacting the phosphor in particulate form with a saturated solution of a composition of formula II in aqueous hydrofluoric acid; A.sub.x[MF.sub.y]; II wherein A is Li, Na, K, Rb, Cs, NR.sub.4 or a combination thereof; M is Si, Ge, Sn, Ti, Zr, Al, Ga, In, Sc, Y, La, Nb, Ta, Bi, Gd, or a combination thereof; R is H, lower alkyl, or a combination thereof; x is the absolute value of the charge of the [MF.sub.y] ion; and y is 5, 6 or 7. In particular embodiments, M is Si, Ge, Sn, Ti, Zr, or a combination thereof.

Color stable manganese-doped phosphors

DOEpatents

Lyons, Robert Joseph [Burnt Hills, NY; Setlur, Anant Achyut [Niskayuna, NY; Deshpande, Anirudha Rajendra [Twinsburg, OH; Grigorov, Ljudmil Slavchev [Sofia, BG

2012-08-28

A process for preparing color stable Mn.sup.+4 doped phosphors includes providing a phosphor of formula I; A.sub.x[MF.sub.y]:Mn.sup.+4 I and contacting the phosphor in particulate form with a saturated solution of a composition of formula II in aqueous hydrofluoric acid; A.sub.x[MF.sub.y]; II wherein A is Li, Na, K, Rb, Cs, NR.sub.4 or a combination thereof; M is Si, Ge, Sn, Ti, Zr, Al, Ga, In, Sc, Y, La, Nb, Ta, Bi, Gd, or a combination thereof; R is H, lower alkyl, or a combination thereof; x is the absolute value of the charge of the [MF.sub.y] ion; and y is 5, 6 or 7. In particular embodiments, M is Si, Ge, Sn, Ti, Zr, or a combination thereof. A lighting apparatus capable of emitting white light includes a semiconductor light source; and a phosphor composition radiationally coupled to the light source, and which includes a color stable Mn.sup.+4 doped phosphor.

78 FR 5776 - University of Colorado Boulder, et al.; Notice of Consolidated Decision on Applications for Duty...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-01-28

... capabilities of this instrument are expanded spectral reach, x-ray beams with controllable polarization, and... optical antennas, plasmonics in metals and semiconductors (including graphene), photonic crystals, and... the Linac Coherent Light Source II project's ray probe pulses with controllable inter-pulse time delay...

Combustion Processes Indoors: a Source of High OH Radical Concentrations Through the Photolysis of Hono

NASA Astrophysics Data System (ADS)

Bartolomei, V.; Gomez Alvarez, E.; Glor, M.; Gligorovski, S.; Temime-Roussel, B.; Quivet, E.; Strekowski, R.; Zetzsch, C.; Held, A. B.; Wortham, H.

2013-12-01

Hydroxyl radical (OH) is one of the most important oxidant species in the atmosphere controlling its self-oxidizing capacity. The main sources of OH radicals are photolysis of ozone and photolysis of nitrous acid (HONO), among the others. In the indoor air, the ozonolysis of alkenes has been suggested as the main OH formation pathway. The possibility for OH formation through photolytic pathways in the indoor environment has been, up to now, ignored (Gómez Alvarez et al., 2012). Models and indirect measurements to the present time predicted concentrations of OH radicals in the order of 104 -105 cm-3. Recently, by direct measurements we have detected high OH radical concentrations of 1.8 106 cm-3 in a classroom in Marseille and we demonstrated that its main source is the photolysis of HONO (Gómez Alvarez et al., 2013). The concentrations of HONO are quite high indoors, reaching levels in the order of a few tens of ppbV (Gómez Alvarez et al., 2013). This is mainly due to 1) direct combustion sources and 2) heterogeneous reactions of NO2 on the numerous surfaces present in the indoor environment. HONO levels of 30 ppb were measured in a previous campaign carried out in Bayreuth in July 2012 as direct emissions from the combustion of a candle. The combination between so high concentrations of HONO and higher than expected light transmissions indoors (or indoor artificial lighting) could have a significant impact on the OH concentrations indoors which could feasibly become considerably higher than we measured in our school campaign (Gomez Alvarez et al., 2013). In order to evaluate these upper limits under combustion conditions in the indoor environment, we have carried out a campaign in the LOTASC chamber (Bayreuth, Germany). For this aim, the exhaust fumes from the burning of a commonly used domestic candle have been introduced in the chamber. The chamber was irradiated under well research indoor lighting conditions. A thorough characterization of light intensities and span (wavelength distribution) indoors have been performed, which had been identified as a clear flaw in our knowledge restricting the advancement of indoor air quality models. OH concentration levels have been determined using d9-butanol as tracer, using the OH clock determination procedure by PTR-MS-TOF. The OH radical concentration was investigated using different light intensities representative from indoor conditions, both natural and artificial and also different levels of RH. The PSS model has been performed in order to evaluate the contribution of different sources to the OH radical concentrations indoors under these conditions. The obtained results from the PSS model clearly indicate that the main source of OH radical indoors under combustion conditions is the photolysis of HONO under typical indoor irradiation conditions. REFERENCES Gómez Alvarez E, Wortham H, Strekowski R, Zetzsch C, Gligorovski S (2012) Atmospheric photo-sensitized heterogeneous and multiphase reactions: From outdoors to indoors, Environ. Sci. Technol. 46, 1955-1963. Gómez Alvarez, E.; Amedro, D.; Afif, C. ; Gligorovski, S.; Schoemacker , C.; Fittschen, C. ; Doussin, J. F.; Wortham, H. (2013) Unexpectedly high indoor hydroxyl radical concentrations associated with nitrous acid. Proc. Natl. Acad. Sci. USA Accepted.

Light emitting diodes as a plant lighting source

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

Bula, R.J.; Tennessen, D.J.; Morrow, R.C.

1994-12-31

Electroluminescence in solid materials is defined as the generation of light by the passage of an electric current through a body of solid material under an applied electric field. A specific type of electroluminescence, first noted by Lossew in 1923, involves the generation of photons when electrons are passed through a p-n junction of certain solid materials (junction of a n-type semiconductor, an electron donor, and a p-type semiconductor, an electron acceptor). Development efforts to translate these observations into visible light emitting devices, however, was not undertaken until the 1950s. The term, light emitting diode (LEDs), was first used inmore » a report by Wolfe, et al., in 1955. The development of this light emitting semiconductor technology dates back less than 30 years. During this period of time, the LED has evolved from a rare and expensive light generating device to one of the most widely used electronic components. The most popular applications of the LED are as indicators or as optoelectronic switches. However, several recent advances in LED technology have made possible the utilization of LEDs for applications that require a high photon flux, such as for plant lighting in controlled environments. The new generation of LEDs based on a gallium aluminum arsenide (GaAlAS) semiconductor material fabricated as a double heterostructure on a transparent substrate has opened up many new applications for these LEDs.« less

Engendering Long-Term Air and Light Stability of a TiO2-Supported Porphyrinic Dye via Atomic Layer Deposition.

PubMed

Hoffeditz, William L; Son, Ho-Jin; Pellin, Michael J; Farha, Omar K; Hupp, Joseph T

2016-12-21

Organic and porphyrin-based chromophores are prevalent in liquid-junction photovoltaic and photocatalytic solar-cell chemistry; however, their long-term air and light instability may limit their practicality in real world technologies. Here, we describe the protection of a zinc porphyrin dye, adsorbed on nanoparticulate TiO 2 , from air and light degradation by a protective coating of alumina grown with a previously developed post-treatment atomic layer deposition (ALD) technique. The protective Al 2 O 3 ALD layer is deposited using dimethylaluminum isopropoxide as an Al source; in contrast to the ubiquitous ALD precursor trimethylaluminum, dimethylaluminum isopropoxide does not degrade the zinc porphyrin dye, as confirmed by UV-vis measurements. The growth of this protective ALD layer around the dye can be monitored by an in-reactor quartz crystal microbalance (QCM). Furthermore, greater than 80% of porphyrin light absorption is retained over ∼1 month of exposure to air and light when the protective coating is present, whereas almost complete loss of porphyrin absorption is observed in less than 2 days in the absence of the ALD protective layer. Applying the Al 2 O 3 post-treatment technique to the TiO 2 -adsorbed dye allows the dye to remain in electronic contact with both the semiconductor surface and a surrounding electrolyte solution, the combination of which makes this technique promising for numerous other electrochemical photovoltaic and photocatalytic applications, especially those involving the dye-sensitized evolution of oxygen.

A novel method for fast imaging of brain function, non-invasively, with light

NASA Astrophysics Data System (ADS)

Chance, Britton; Anday, Endla; Nioka, Shoko; Zhou, Shuoming; Hong, Long; Worden, Katherine; Li, C.; Murray, T.; Ovetsky, Y.; Pidikiti, D.; Thomas, R.

1998-05-01

Imaging of the human body by any non-invasive technique has been an appropriate goal of physics and medicine, and great success has been obtained with both Magnetic Resonance Imaging (MRI) and Positron Emission Tomography (PET) in brain imaging. Non-imaging responses to functional activation using near infrared spectroscopy of brain (fNIR) obtained in 1993 (Chance, et al. [1]) and in 1994 (Tamura, et al. [2]) are now complemented with images of pre-frontal and parietal stimulation in adults and pre-term neonates in this communication (see also [3]). Prior studies used continuous [4], pulsed [3] or modulated [5] light. The amplitude and phase cancellation of optical patterns as demonstrated for single source detector pairs affords remarkable sensitivity of small object detection in model systems [6]. The methods have now been elaborated with multiple source detector combinations (nine sources, four detectors). Using simple back projection algorithms it is now possible to image sensorimotor and cognitive activation of adult and pre- and full-term neonate human brain function in times < 30 sec and with two dimensional resolutions of < 1 cm in two dimensional displays. The method can be used in evaluation of adult and neonatal cerebral dysfunction in a simple, portable and affordable method that does not require immobilization, as contrasted to MRI and PET.

4.5 W supercontinuum generation from 1017 to 3438 nm in an all-solid fluorotellurite fiber

NASA Astrophysics Data System (ADS)

Jia, Zhixu; Yao, Chuanfei; Jia, Shijie; Wang, Fang; Wang, Shunbin; Zhao, Zhipeng; Qin, Guanshi; Ohishi, Yasutake; Qin, Weiping

2017-06-01

All-solid fluorotellurite fibers are fabricated by using a rod-in-tube method. The core and cladding materials are TeO2-BaF2-Y2O3 (TBY) and AlF3-based glasses, respectively. Since the refractive index (˜1.46) of AlF3-based glass is much lower than that (˜1.84) of TBY glass, the zero-dispersion-wavelength of the fabricated fiber can be tuned from 2145 to 1507 nm by varying the fiber core diameter from 50 to 3 μm. By using a 0.6 m long all-solid fluorotellurite fiber with a core diameter of ˜7 μm as the nonlinear medium and a 2 μm femtosecond fiber laser as the pump source, 4.5 W supercontinuum (SC) generation from 1017 to 3438 nm is obtained for a launched pump power of ˜10.48 W. The corresponding optical-to-optical conversion efficiency is about 42.9%. In addition, no any damage of the fluorotellurite fiber is observed during the operation of the above SC light source. Our results show that all-solid fluorotellurite fibers are promising nonlinear media for constructing high power mid-infrared SC light sources.

Blue-green phosphor for fluorescent lighting applications

DOEpatents

Srivastava, Alok; Comanzo, Holly; Manivannan, Venkatesan; Setlur, Anant Achyut

2005-03-15

A fluorescent lamp including a phosphor layer including Sr.sub.4 Al.sub.14 O.sub.25 :Eu.sup.2+ (SAE) and at least one of each of a red, green and blue emitting phosphor. The phosphor layer can optionally include an additional, deep red phosphor and a yellow emitting phosphor. The resulting lamp will exhibit a white light having a color rendering index of 90 or higher with a correlated color temperature of from 2500 to 10000 Kelvin. The use of SAE in phosphor blends of lamps results in high CRI light sources with increased stability and acceptable lumen maintenance over, the course of the lamp life.

The BATSE Earth Occultation Catalog of Low Energy Gamma Ray Sources

NASA Technical Reports Server (NTRS)

Harmon, B. A.; Wilson-Hodge, C. A.; Fishman, G. J.; Paciesas, W. S.; Zhang, S. N.; Finger, M. H.; Connaughton, V.; Koshut, T. M.; Henze, W.; McCollough, M. L.;

Slow Orbit Feedback at the ALS Using Matlab

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

Portmann, G.

1999-03-25

The third generation Advanced Light Source (ALS) produces extremely bright and finely focused photon beams using undulatory, wigglers, and bend magnets. In order to position the photon beams accurately, a slow global orbit feedback system has been developed. The dominant causes of orbit motion at the ALS are temperature variation and insertion device motion. This type of motion can be removed using slow global orbit feedback with a data rate of a few Hertz. The remaining orbit motion in the ALS is only 1-3 micron rms. Slow orbit feedback does not require high computational throughput. At the ALS, the globalmore » orbit feedback algorithm, based on the singular valued decomposition method, is coded in MATLAB and runs on a control room workstation. Using the MATLAB environment to develop, test, and run the storage ring control algorithms has proven to be a fast and efficient way to operate the ALS.« less

Comparison of the bidirectional reflectance distribution function of various surfaces

NASA Astrophysics Data System (ADS)

Fernandez, Rene; Seasholtz, Richard G.; Oberle, Lawrence G.; Kadambi, Jaikrishnan R.

1989-04-01

This paper describes the development and use of a system to measure the bidirectional reflectance distribution function (BRDF) of various surfaces. The BRDF measurements are to be used in the analysis and design of optical measurement systems such as laser anemometers. An Ar-ion laser (514 nm) was the light source. Preliminary results are presented for eight samples: two glossy black paints, two flat black paints, black glass, sand-blasted Al, unworked Al, and a white paint. A BaSO4 white reflectance standard was used as the reference sample throughout the tests.

AlGaInN laser diode technology for free-space and plastic optical fibre telecom applications

NASA Astrophysics Data System (ADS)

Najda, S. P.; Perlin, P.; Suski, T.; Marona, L.; Bóckowski, M.; Leszczyński, M.; Wisniewski, P.; Czernecki, R.; Kucharski, R.; Targowski, G.; Watson, S.; Kelly, A. E.; Watson, M. A.; Blanchard, P.; White, H.

2016-03-01

Gallium Nitride laser diodes fabricated from the AlGaInN material system is an emerging technology for laser sources from the UV to visible and is a potential key enabler for new system applications such as free-space (underwater & air bourne links) and plastic optical fibre telecommunications. We measure visible light (free-space and underwater) communications at high frequency (up to 2.5 Gbit/s) and in plastic optical fibre (POF) using a directly modulated GaN laser diode.

Light induced dielectric constant of Alumina doped lead silicate glass based on silica sands

NASA Astrophysics Data System (ADS)

Diantoro, Markus; Natalia, Desi Ayu; Mufti, Nandang; Hidayat, Arif

2016-04-01

Numerous studies on glass ceramic compounds have been conducted intensively. Two major problems to be solved are to simplify the fabrication process by reducing melting temperature as well as improving various properties for various fields of technological application. To control the dielectric constant, the researchers generally use a specific dopant. So far there is no comprehensive study to control the dielectric constant driven by both of dopant and light intensity. In this study it is used Al2O3 dopant to increase the light induced dielectric constant of the glass. The source of silica was taken from local silica sands of Bancar Tuban. The sands were firstly leached using hydrochloric acid to improve the purity of silica which was investigated by means of XRF. Fabricating the glass samples were performed by using melting-glass method. Silica powder was mixed with various ratio of SiO2:Na2CO3:PbO:Al2O3. Subsequently, a mixture of various Al2O3 doped lead silicate glasses were melted at 970°C and directy continued by annealed at 300°C. The samples were investigated by XRD, FTIR, SEM-EDX and measuring dielectric constant was done using dc-capacitance meter with various light intensities. The investigation result of XRD patterns showed that the crystal structures of the samples are amorphous state. The introduction of Al2O3 does not alter the crystal structure, but significantly change the structure of the functional glass bonding PbO-SiO2 which was shown by the FTIR spectra. It was noted that some new peak peaks were exist in the doped samples. Measuring result of dielectricity shows that the dielectric constant of glass increases with the addition of Al2O3. Increasing the light intensity gives rise to increase their dielectric constant in general. A detail observation of the dielectric seen that there are discontinuous step-like of dielectric. Most likely a specific quantization mechanism occurs when glass exposed under light.

Addressing Physics Grand Challenges Using the Jefferson Lab FEL

NASA Astrophysics Data System (ADS)

Williams, Gwyn P.

2006-11-01

The Jefferson Lab Free Electron Laser[1] is the first of the so-called 4^th generation light sources to go operational. Capable of delivering extraordinarily bright, tunable light in ultrafast pulses from THz[2] through infrared to UV, the facility extends the experimental reach of accelerator-based light-sources by many orders of magnitude. This allows new opportunities to study many of the ``Grand Challenges'' recently defined by the Office of Science, Basic Energy Sciences Division, most of which are concerned with understandings of equilibrium and non-equilibrium behavior of materials in physics, chemistry and biology using precise pump and probe techniques. Specifically, in condensed matter physics, the JLab FEL permits new studies which go beyond earlier studies of reductionist behavior to those which examine emergent behavior. Thus, the understanding of high Tc superconductivity, colossal magneto-resistance, and observations of the breakdown of the Born-Oppenheimer approximation, are examples of collective behavior which is now treated theoretically via the concept of quasiparticles. In this presentation we will describe the dual pathways of light source development and physics challenges, and then show how they are combined in experiments that allow new insights to be developed to understand material function. We will illustrate this with details of the evolution of accelerator-based light sources, and with examples of work performed to date. References: [1] Neil et al. Phys. Rev.Letts 84, 662 (2000). [2] Carr, Martin, McKinney, Neil, Jordan & Williams, Nature 420, 153 (2002).

Local Plasticity of Al Thin Films as Revealed by X-Ray Microdiffraction

NASA Astrophysics Data System (ADS)

Spolenak, R.; Brown, W. L.; Tamura, N.; MacDowell, A. A.; Celestre, R. S.; Padmore, H. A.; Valek, B.; Bravman, J. C.; Marieb, T.; Fujimoto, H.; Batterman, B. W.; Patel, J. R.

2003-03-01

Grain-to-grain interactions dominate the plasticity of Al thin films and establish effective length scales smaller than the grain size. We have measured large strain distributions and their changes under plastic strain in 1.5-μm-thick Al0.5%Cu films using a 0.8-μm-diameter white x-ray probe at the Advanced Light Source. Strain distributions arise not only from the distribution of grain sizes and orientation, but also from the differences in grain shape and from stress environment. Multiple active glide plane domains have been found within single grains. Large grains behave like multiple smaller grains even before a dislocation substructure can evolve.

Effects of Noise, Temperature, Humidity, Motion and Light on the Sleep Patterns of the Crew of HSV-2 SWIFT

DTIC Science & Technology

2005-09-01

22 4. Soundscape ...traffic noise, while Fidel et al. (2000) examined aircraft noise exposure. 4. Soundscape In residential settings there are noise soundscapes . A... soundscape is physically defined by noise source location (e.g., streets), barriers such as buildings and quiet areas. A perceived soundscape is the

Reference Interferometer Using a Semiconductor Laser/LED Reference Source in a Cryogenic Fourier-Transform Spectrometer

NASA Technical Reports Server (NTRS)

Martino, Anthony J.; Cornwell, Donald M.

1998-01-01

A combination of a single mode AlGaAs laser diode and broadband LED was used in a Michelson interferometer to provide reference signals in a Fourier transform spectrometer, the Composite Infrared Spectrometer, on the Cassini mission to Saturn. The narrowband light from the laser produced continuous fringes throughout the travel of the interferometer, which were used to control the velocity of the scan mechanism and to trigger data sampling. The broadband light from the LED produced a burst of fringes at zero path difference, which was used as a fixed position reference. The system, including the sources, the interferometer, and the detectors, was designed to work both at room temperature and instrument operating temperature of 170 Kelvin. One major challenge that was overcome was preservation, from room temperature to 170 K, of alignment sufficient for high modulation of fringes from the broadband source. Another was the shift of the source spectra about 30 nm toward shorter wavelengths upon cooldown.

Bound-to-bound midinfrared intersubband absorption in carbon-doped GaAs /AlGaAs quantum wells

NASA Astrophysics Data System (ADS)

Malis, Oana; Pfeiffer, Loren N.; West, Kenneth W.; Sergent, A. Michael; Gmachl, Claire

2005-08-01

Bound-to-bound intersubband absorption in the valence band of modulation-doped GaAs quantum wells with digitally alloyed AlGaAs barriers was studied in the midinfrared wavelength range. A high-purity solid carbon source was used for the p-type doping. Strong narrow absorption peaks due to heavy-to-heavy hole transitions are observed with out-of-plane polarized light, and weaker broader features with in-plane polarized light. The heavy-to-heavy hole transition energy spans the spectral range between 206 to 126 meV as the quantum well width is increased from 25 to 45 Å. The experimental results are found to be in agreement with calculations of a six-band k •p model taking into account the full band structure of the digital alloy.

Photo-induced formation of nitrous acid (HONO) on protein surfaces

NASA Astrophysics Data System (ADS)

Meusel, Hannah; Elshorbany, Yasin; Bartels-Rausch, Thorsten; Selzle, Kathrin; Lelieveld, Jos; Ammann, Markus; Pöschl, Ulrich; Su, Hang; Cheng, Yafang

2014-05-01

The study of nitrous acid (HONO) is of great interest, as the photolysis of HONO leads to the OH radical, which is the most important oxidant in the troposphere. HONO is directly emitted by combustion of fossil fuel and from soil biogenic nitrite (Su et al., 2011), and can also be formed by gas phase reactions of NO and OH and heterogeneous reactions of NO2. Previous atmospheric measurements have shown unexpectedly high HONO concentrations during daytime. Measured mixing ratios were about one order of magnitude higher than model simulations (Kleffmann et al. 2005, Vogel et al. 2003). The additional daytime source of HONO might be attributed to the photolysis of adsorbed nitric acid or heterogeneous photochemistry of NO2 on organic substrates, such as humic acids or polyphenolic compounds (Stemmler et al., 2006), or indirectly through nitration of phenols and subsequent photolysis of nitrophenols (Sosedova et al., 2011, Bejan et al., 2006). An important reactive surface for the heterogeneous formation of HONO could involve proteins, which are ubiquitous in the environment. They are part of coarse biological aerosol particles like pollen grains, fine particles (fragments of pollen, microorganism, plant debris) and dissolved in rainwater, soil and road dust (Miguel et al. 1999). In this project a thin film of bovine serum albumin (BSA), a model protein with 67 kDa and 21 tyrosine residues per molecule, is irradiated and exposed to nitrogen dioxide in humidified nitrogen. The formation of HONO is measured with long path absorption photometry (LOPAP). The generated HONO is in the range of 100 to 1100 ppt depending on light intensity, NO2 concentration and film thickness. Light induced HONO formation on protein surfaces is stable over the 20-hours experiment of irradiation and exposure. On the other hand, light activated proteins reacting with NO2 form nitrated proteins, as detected by liquid chromatography (LC-DAD). Our experiments on tetranitromethane (TNM) nitrated ovalbumin (OVA) also show a clear light induced decomposition of nitrated proteins with HONO identified as one of the major products. This suggests a shortening of the lifetime of nitrated proteins during daytime. Our results indicate an important role of light to the fate of proteins, and through HONO, important OH precursors. Proteins and nitrated proteins on aerosol and ground surfaces may therefore influence the atmospheric chemistry and contribute to the oxidation capacity. References Bejan, I. et al., Physical Chemistry Chemical Physics 2006, 8 (17), 2028-2035. Kleffmann, J. et al., Geophysical Research Letters 2005, 32 (5). Miguel, A. G. et al., Environmental Science & Technology 1999, 33 (23), 4159-4168. Sosedova, Y., et al., Photochemical and Photobiological Sciences 2011, 10, 1680-1690. Stemmler, K. et al., Nature 2006, 440 (7081), 195-198. Su et al., Science 2010, 333, 1616-1618. Vogel, B. et al., Atmospheric Environment 2003, 37 (21), 2957-2966.

600 eV falcon-linac thomson x-ray source

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

Crane, J K; LeSage, G P; Ditmire, T

2000-12-15

The advent of 3rd generation light sources such as the Advanced Light Source (ALS) at LBL, and the Advanced Photon Source at Argonne, have produced a revolution in x-ray probing of dense matter during the past decade. These machines use electron-synchrotrons in conjunction with undulator stages to produce 100 psec x-ray pulses with photon energies of several kiloelectronvolts (keV). The applications for x-ray probing of matter are numerous and diverse with experiments in medicine and biology, semiconductors and materials science, and plasma and solid state physics. In spite of the success of the 3rd generation light sources there is strongmore » motivation to push the capabilities of x-ray probing into new realms, requiring shorter pulses, higher brightness and harder x-rays. A 4th generation light source, the Linac Coherent Light Source (LCLS), is being considered at the Stanford Linear Accelerator [1]. The LCLS will produce multi-kilovolt x-rays of subpicosecond duration that are 10 orders of magnitude brighter than today's 3rd generation light sources.[1] Although the LCLS will provide unprecedented capability for performing time-resolved x-ray probing of ultrafast phenomena at solid densities, this machine will not be completed for many years. In the meantime there is a serious need for an ultrashort-pulse, high-brightness, hard x-ray source that is capable of probing deep into high-Z solid materials to measure dynamic effects that occur on picosecond time scales. Such an instrument would be ideal for probing the effects of shock propagation in solids using Bragg and Laue diffraction. These techniques can be used to look at phase transitions, melting and recrystallization, and the propagation of defects and dislocations well below the surface in solid materials. [2] These types of dynamic phenomena undermine the mechanical properties of metals and are of general interest in solid state physics, materials science, metallurgy, and have specific relevance to stockpile stewardship. Another x-ray diagnostic technique, extended x-ray absorption fine structure (EXAFS) spectroscopy, can be used to measure small-scale structural changes to understand the underlying atomic physics associated with the formation of defects. [2]« less

Deep UV LEDs

NASA Astrophysics Data System (ADS)

Han, Jung; Amano, Hiroshi; Schowalter, Leo

2014-06-01

Deep ultraviolet (DUV) photons interact strongly with a broad range of chemical and biological molecules; compact DUV light sources could enable a wide range of applications in chemi/bio-sensing, sterilization, agriculture, and industrial curing. The much shorter wavelength also results in useful characteristics related to optical diffraction (for lithography) and scattering (non-line-of-sight communication). The family of III-N (AlGaInN) compound semiconductors offers a tunable energy gap from infrared to DUV. While InGaN-based blue light emitters have been the primary focus for the obvious application of solid state lighting, there is a growing interest in the development of efficient UV and DUV light-emitting devices. In the past few years we have witnessed an increasing investment from both government and industry sectors to further the state of DUV light-emitting devices. The contributions in Semiconductor Science and Technology 's special issue on DUV devices provide an up-to-date snapshot covering many relevant topics in this field. Given the expected importance of bulk AlN substrate in DUV technology, we are pleased to include a review article by Hartmann et al on the growth of AlN bulk crystal by physical vapour transport. The issue of polarization field within the deep ultraviolet LEDs is examined in the article by Braut et al. Several commercial companies provide useful updates in their development of DUV emitters, including Nichia (Fujioka et al ), Nitride Semiconductors (Muramoto et al ) and Sensor Electronic Technology (Shatalov et al ). We believe these articles will provide an excellent overview of the state of technology. The growth of AlGaN heterostructures by molecular beam epitaxy, in contrast to the common organo-metallic vapour phase epitaxy, is discussed by Ivanov et al. Since hexagonal boron nitride (BN) has received much attention as both a UV and a two-dimensional electronic material, we believe it serves readers well to include the article by Jiang et al on using BN for UV devices; potentially as a p-type wide band gap semiconductor contact. Finally, an in-depth discussion of one DUV application in defense, the non-line-of-sight (NLOS) communication, is given by Drost and Sadler. Overall, we believe that this special issue of Semiconductor Science and Technology provides a useful overview of the state-of-art in the field on DUV materials and devices. In view of the rapidly growing interest in this field, the demonstrated enhanced device performance, and the wide range of applications, this special issue can be considered a very timely contribution. Finally, we would like to thank the IOP editorial staff, in particular Alice Malhador, for their support and also like to thank all contributors for their efforts to make this special issue possible.

AZO films with Al nano-particles to improve the light extraction efficiency of GaN-based light-emitting diodes

NASA Astrophysics Data System (ADS)

Chou, Ying-Hung; Yan, Jheng-Tai; Lee, Hsin-Ying; Lee, Ching-Ting

2008-02-01

The co-sputtering Al-doped ZnO (AZO) films with Al nano-particles were used to increase the extraction efficiency of GaN-based light-emitting diodes (LEDs). Fixing the ZnO radio frequency (RF) power of 100W and changing the Al DC power from 0 to 13W, the AZO films with various Al contents can be obtained. In the experimental results, the AZO films deposited with Al DC power of 0, 4.5 and 7W do not have Al segregation. However, the segregated Al nano-particles can be found in the AZO films deposited by Al DC power of 10W and 13W. The co-sputtering 170 nm-thick AZO films with and without Al nano-particles were deposited on the transparent area of LEDs and compared the light output intensity of conventional LEDs. The light intensity of LEDs with AZO films with Al DC power 0, 4.5 and 7W increased 10% than that of conventional LEDs. This was due to the AZO film played a role of anti-reflection coating (ARC) layer. The light intensity of LEDs with AZO film deposited using Al DC power of 10W and 13W increased about 35% and 30%, respectively. It can be deduced that the output light is scattered by the Al nano-particles existed in the AZO film.

Luminescence properties of Na2Sr2Al2PO4Cl9:Sm3+ phosphor

NASA Astrophysics Data System (ADS)

Tamboli, Sumedha; Shahare, D. I.; Dhoble, S. J.

2018-04-01

A series of Sm3+ ions doped Na2Sr2Al2PO4Cl9 phosphors were synthesized via solid state synthesis method. Photoluminescence (PL) emission spectra were obtained by keeping excitation wavelength at 406 nm. Emission spectra show three emission peaks at 563 nm, 595 nm and 644 nm. The CIE chromaticity diagram shows emission colour of the phosphor in the orange-red region of the visible spectrum, indicating that the phosphor may be useful in preparing orange light-emitting diodes. Na2Sr2Al2PO4Cl9:Sm3+ phosphors were irradiated by γ-rays from a 60Co source and β-rays from a 90Sr source. Their thermoluminescence (TL) glow curves were obtained by Nucleonix 1009I TL reader. TL Trapping parameters such as activation energy of trapped electrons and order of kinetics were obtained by using Chen's peak shape method, Glow curve fitting method and initial rise method.

Luminescent properties of Al2O3:Ce single crystalline films under synchrotron radiation excitation

NASA Astrophysics Data System (ADS)

Zorenko, Yu.; Zorenko, T.; Gorbenko, V.; Savchyn, V.; Voznyak, T.; Fabisiak, K.; Zhusupkalieva, G.; Fedorov, A.

2016-09-01

The paper is dedicated to study the luminescent and scintillation properties of the Al2O3:Ce single crystalline films (SCF) grown by LPE method onto saphire substrates from PbO based flux. The structural quality of SCF samples was investigated by XRD method. For characterization of luminescent properties of Al2O3:Ce SCFs the cathodoluminescence spectra, scintillation light yield (LY) and decay kinetics under excitation by α-particles of Pu239 source were used. We have found that the scintillation LY of Al2O3:Ce SCF samples is relatively large and can reach up to 50% of the value realized in the reference YAG:Ce SCF. Using the synchrotron radiation excitation in the 3.7-25 eV range at 10 K we have also determined the basic parameters of the Ce3+ luminescence in Al2O3 host.

Chemistry and biology of phototropism-regulating substances in higher plants.

PubMed

Yamamura, S; Hasegawa, K

2001-01-01

Most people are familiar with the sight of a young seedling bending towards a window or the brightest source of light to which it is exposed. This directional growth response is known as phototropism, which is caused by a lateral growth-promoting auxin in the bending organ (Cholodny-Went theory, cited in high school textbook). Recently, however, Bruinsma et al., Weiler et al., and Hasegawa et al. independently found that the shaded half did not contain more auxin than the illuminated one. Instead it was found that the even distribution of auxin was accompanied by a lateral gradient of growth inhibiting substances during phototropic curvature (Bruinsma-Hasegawa theory). We have isolated some photo-induced growth inhibitory substances related to phototropism, benzoxazolinones from light-grown maize shoots (Zea mays L.), raphanusanins from radish hypocotyl (Raphanus sativus var. hortensis f. gigantissimus M.), indolyacetonitrile from light-grown shoots (Brassica oleacea L.), 8-epixanthatin from sunflower hypocotyl (Helianthus annus L.), and quite recently uridine from oat coleoptile (Avena sativa L.). Chemical analyses have shown phototropic stimulations to cause curvature by inducing a local unequal distribution of growth-inhibiting substances that antagonize auxin in its cell-elongating activity. Finally, a model is presented for further studies on phototropism. Copyright 2001 The Japan Chemical Journal Forum and John Wiley & Sons, Inc.

Impact of laser phase and amplitude noises on streak camera temporal resolution

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

Wlotzko, V., E-mail: wlotzko@optronis.com; Optronis GmbH, Ludwigstrasse 2, 77694 Kehl; Uhring, W.

2015-09-15

Streak cameras are now reaching sub-picosecond temporal resolution. In cumulative acquisition mode, this resolution does not entirely rely on the electronic or the vacuum tube performances but also on the light source characteristics. The light source, usually an actively mode-locked laser, is affected by phase and amplitude noises. In this paper, the theoretical effects of such noises on the synchronization of the streak system are studied in synchroscan and triggered modes. More precisely, the contribution of band-pass filters, delays, and time walk is ascertained. Methods to compute the resulting synchronization jitter are depicted. The results are verified by measurement withmore » a streak camera combined with a Ti:Al{sub 2}O{sub 3} solid state laser oscillator and also a fiber oscillator.« less

Modernized Approach for Generating Reproducible Heterogeneity Using Transmitted-Light for Flow Visualization Experiments

NASA Astrophysics Data System (ADS)

Jones, A. A.; Holt, R. M.

2017-12-01

Image capturing in flow experiments has been used for fluid mechanics research since the early 1970s. Interactions of fluid flow between the vadose zone and permanent water table are of great interest because this zone is responsible for all recharge waters, pollutant transport and irrigation efficiency for agriculture. Griffith, et al. (2011) developed an approach where constructed reproducible "geologically realistic" sand configurations are deposited in sandfilled experimental chambers for light-transmitted flow visualization experiments. This method creates reproducible, reverse graded, layered (stratified) thin-slab sand chambers for point source experiments visualizing multiphase flow through porous media. Reverse-graded stratification of sand chambers mimic many naturally occurring sedimentary deposits. Sandfilled chambers use light as nonintrusive tools for measuring water saturation in two-dimensions (2-D). Homogeneous and heterogeneous sand configurations can be produced to visualize the complex physics of the unsaturated zone. The experimental procedure developed by Griffith, et al. (2011) was designed using now outdated and obsolete equipment. We have modernized this approach with new Parker Deadel linear actuator and programed projects/code for multiple configurations. We have also updated the Roper CCD software and image processing software with the latest in industry standards. Modernization of transmitted-light source, robotic equipment, redesigned experimental chambers, and newly developed analytical procedures have greatly reduced time and cost per experiment. We have verified the ability of the new equipment to generate reproducible heterogeneous sand-filled chambers and demonstrated the functionality of the new equipment and procedures by reproducing several gravity-driven fingering experiments conducted by Griffith (2008).

Revisit the modeling of the Saturnian ring atmosphere and ionosphere from the "Cassini Grand Finale" results

NASA Astrophysics Data System (ADS)

Tseng, W. L.; Johnson, R. E.; Tucker, O. J.; Perry, M. E.; Ip, W. H.

2017-12-01

During the Cassini Grand Finale mission, this spacecraft, for the first time, has done the in-situ measurements of Saturn's upper atmosphere and its rings and provides critical information for understanding the coupling dynamics between the main rings and the Saturnian system. The ring atmosphere is the source of neutrals (i.e., O2, H2, H; Tseng et al., 2010; 2013a), which is primarily generated by photolytic decomposition of water ice (Johnson et al., 2006), and plasma (i.e., O2+ and H2+; Tseng et al., 2011) in the Saturnian magnetosphere. In addition, the main rings have strong interaction with Saturn's atmosphere and ionosphere (i.e., a source of oxygen into Saturn's upper atmosphere and/or the "ring rain" in O'Donoghue et al., 2013). Furthermore, the near-ring plasma environment is complicated by the neutrals from both the seasonally dependent ring atmosphere and Enceladus torus (Tseng et al., 2013b), and, possibly, from small grains from the main and tenuous F and G rings (Johnson et al.2017). The data now coming from Cassini Grand Finale mission already shed light on the dominant physics and chemistry in this region of Saturn's magnetosphere, for example, the presence of carbonaceous material from meteorite impacts in the main rings and each gas species have similar distribution in the ring atmosphere. We will revisit the details in our ring atmosphere/ionosphere model to study, such as the source mechanism for the organic material and the neutral-grain-plasma interaction processes.

Differences in photoluminescence properties and thermal degradation between nanoparticle and bulk particle BaMgAl10O17:Eu2+ phosphors under UV?VUV irradiation.

PubMed

Liu, Bitao; Xin, Shuangyu; Li, Fenghua; Zhang, Jiachi; Wang, Yuhua

2014-05-01

BaMgAl10O17:Eu2+ (BAM) phosphors used for plasma display panels and three-band fluorescence lamps are exposed to an oxidizing environment at about 500 degrees C, which is currently unavoidable in actual applications. We investigated the mechanism of the luminance degradation of BAM caused by annealing at 500 degrees C based on the difference in luminance degradation of bulk particle and nanoparticle samples under various excitation source irradiations. When the samples were excited by the different light sources, more than 30% degradation of luminance occurred under 147 nm while less than 10% degradation occurred under 254 nm both for nanoparticle and bulk particle samples. In addition, the luminescence degradation of nanophosphors shows a different tendency compared to the bulk phosphors. With a model based on the particle size and excitation light penetration depth, we demonstrate that the degradation is still mainly ascribed to the oxidized of divalent Eu. The differences in luminescence properties between nanophosphors and bulk phosphors are also illustrated by this model. As a result, the potential industrial applications of nanophosphors are evaluated.

Frequency mixing crystal

DOEpatents

Ebbers, Christopher A.; Davis, Laura E.; Webb, Mark

1992-01-01

In a laser system for converting infrared laser light waves to visible light comprising a source of infrared laser light waves and means of harmoic generation associated therewith for production of light waves at integral multiples of the frequency of the original wave, the improvement of said means of harmonic generation comprising a crystal having the chemical formula X.sub.2 Y(NO.sub.3).sub.5 .multidot.2 nZ.sub.2 o wherein X is selected from the group consisting of Li, Na, K, Rb, Cs, and Tl; Y is selected from the group consisting of Sc, Y, La, Ce, Nd, Pr, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Al, Ga, and In; Z is selected from the group consisting of H and D; and n ranges from 0 to 4.

Enhancing integration of articular cartilage grafts via photochemical bonding.

PubMed

Arvayo, Alberto L; Wong, Ivan J; Dragoo, Jason L; Levenston, Marc E

2018-03-25

The integration of osteochondral grafts to native articular cartilage is critical as the lack of graft integration may lead to continued tissue degradation, poor load transfer and inadequate nutrient transport. Photochemical bonding promotes graft integration by activating a photosensitizer at the interface via a light source and avoids negative effects associated with other bonding techniques. We hypothesized that the bond strength depends on photosensitizer type and concentration in addition to light exposure. Photochemical bonding was evaluated using methylene blue (MB), a cationic phenothiazine photosensitizer, and two phthalocyanine photosensitizers, Al(III) phthalocyanine chloride tetrasulfonic acid (CASPc) and aluminum phthalocyanine chloride (AlPc). Exposure was altered by varying irradiation time for a fixed irradiance or by varying irradiance with a fixed irradiation time. MB was ineffective at producing bonding at the range of concentrations tested while CASPc produced a peak twofold bond strength increase over controls. AlPc produced substantial bonding at all concentrations with a peak 3.9-fold bond strength increase over controls. Parametric tests revealed that bond strength depended primarily on the total energy delivered to the bonding site rather than the rate of light delivery or light irradiance. Bond strength persisted for 1 week of in-vitro culture, which warrants further exploration for clinical applications. These studies indicate that photochemical bonding is a viable strategy for enhancing articular cartilage graft integration. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.

Spatial Reasoning Training Through Light Curves Of Model Asteroids

NASA Astrophysics Data System (ADS)

Ziffer, Julie; Nakroshis, Paul A.; Rudnick, Benjamin T.; Brautigam, Maxwell J.; Nelson, Tyler W.

2015-11-01

Recent research has demonstrated that spatial reasoning skills, long known to be crucial to math and science success, are teachable. Even short stints of training can improve spatial reasoning skills among students who lack them (Sorby et al., 2006). Teaching spatial reasoning is particularly valuable to women and minorities who, through societal pressure, often doubt their spatial reasoning skill (Hill et al., 2010). We have designed a hands on asteroid rotation lab that provides practice in spatial reasoning tasks while building the student’s understanding of photometry. For our tool, we mount a model asteroid, with any shape of our choosing, on a slowly rotating motor shaft, whose speed is controlled by the experimenter. To mimic an asteroid light curve, we place the model asteroid in a dark box, shine a movable light source upon our asteroid, and record the light reflected onto a moveable camera. Students may then observe changes in the light curve that result from varying a) the speed of rotation, b) the model asteroid’s orientation with respect to the motor axis, c) the model asteroid’s shape or albedo, and d) the phase angle. After practicing with our tool, students are asked to pair new objects to their corresponding light curves. To correctly pair objects to their light curves, students must imagine how light scattering off of a three dimensional rotating object is imaged on a ccd sensor plane, and then reduced to a series of points on a light curve plot. Through the use of our model asteroid, the student develops confidence in spatial reasoning skills.

High-gain AlGaAs/GaAs double heterojunction Darlington phototransistors for optical neural networks

NASA Technical Reports Server (NTRS)

Kim, Jae H. (Inventor); Lin, Steven H. (Inventor)

1991-01-01

High-gain MOCVD-grown (metal-organic chemical vapor deposition) AlGaAs/GaAs/AlGaAs n-p-n double heterojunction bipolar transistors (DHBTs) and Darlington phototransistor pairs are provided for use in optical neural networks and other optoelectronic integrated circuit applications. The reduced base doping level used results in effective blockage of Zn out-diffusion, enabling a current gain of 500, higher than most previously reported values for Zn-diffused-base DHBTs. Darlington phototransitor pairs of this material can achieve a current gain of over 6000, which satisfies the gain requirement for optical neural network designs, which advantageously may employ neurons comprising the Darlington phototransistor pairs in series with a light source.

Positive matrix factorization of PM2.5 - eliminating the effects of gas/particle partitioning of semivolatile organic compounds.

PubMed

Xie, M; Barsanti, K C; Hannigan, M P; Dutton, S J; Vedal, S

2013-01-01

Gas-phase concentrations of semi-volatile organic compounds (SVOCs) were calculated from gas/particle (G/P) partitioning theory using their measured particle-phase concentrations. The particle-phase data were obtained from an existing filter measurement campaign (27 January 2003-2 October 2005) as a part of the Denver Aerosol Sources and Health (DASH) study, including 970 observations of 71 SVOCs (Xie et al., 2013). In each compound class of SVOCs, the lighter species (e.g. docosane in n alkanes, fluoranthene in PAHs) had higher total concentrations (gas + particle phase) and lower particle-phase fractions. The total SVOC concentrations were analyzed using positive matrix factorization (PMF). Then the results were compared with source apportionment results where only particle-phase SVOC concentrations were used (particle only-based study; Xie et al., 2013). For the particle only-based PMF analysis, the factors primarily associated with primary or secondary sources ( n alkane, EC/sterane and inorganic ion factors) exhibit similar contribution time series ( r = 0.92-0.98) with their corresponding factors ( n alkane, sterane and nitrate+sulfate factors) in the current work. Three other factors (light n alkane/PAH, PAH and summer/odd n alkane factors) are linked with pollution sources influenced by atmospheric processes (e.g. G/P partitioning, photochemical reaction), and were less correlated ( r = 0.69-0.84) with their corresponding factors (light SVOC, PAH and bulk carbon factors) in the current work, suggesting that the source apportionment results derived from particle-only SVOC data could be affected by atmospheric processes. PMF analysis was also performed on three temperature-stratified subsets of the total SVOC data, representing ambient sampling during cold (daily average temperature < 10 °C), warm (≥ 10 °C and ≤ 20 °C) and hot (> 20 °C) periods. Unlike the particle only-based study, in this work the factor characterized by the low molecular weight (MW) compounds (light SVOC factor) exhibited strong correlations ( r = 0.82-0.98) between the full data set and each sub-data set solution, indicating that the impacts of G/P partitioning on receptor-based source apportionment could be eliminated by using total SVOC concentrations.

Optically controlled polarization in highly oriented ferroelectric thin films

NASA Astrophysics Data System (ADS)

Borkar, Hitesh; Tomar, M.; Gupta, Vinay; Katiyar, Ram S.; Scott, J. F.; Kumar, Ashok

2017-08-01

The out-of-plane and in-plane polarization of (Pb0.6Li0.2Bi0.2)(Zr0.2Ti0.8)O3 (PLBZT) thin film has been studied in the dark and under illumination from a weak light source of a comparable bandgap. A highly oriented PLBZT thin film was grown on a LaNiO3/LaAlO3 substrate by pulsed laser deposition; it showed well-saturated polarization which was significantly enhanced under light illumination. We employed two configurations for polarization characterization: the first deals with out-of-plane polarization with a single capacitor under investigation, whereas the second uses two capacitors connected in series via the bottom electrode. Two different configurations were illuminated using different energy sources and their effects were studied. The latter configuration shows a significant change in polarization under light illumination that may provide an extra degree of freedom for device miniaturization. The polarization was also tested using positive-up and negative-down measurements, confirming robust polarization and its switching under illumination.

Optical nonclassicality test based on third-order intensity correlations

NASA Astrophysics Data System (ADS)

Rigovacca, L.; Kolthammer, W. S.; Di Franco, C.; Kim, M. S.

2018-03-01

We develop a nonclassicality criterion for the interference of three delayed, but otherwise identical, light fields in a three-mode Bell interferometer. We do so by comparing the prediction of quantum mechanics with those of a classical framework in which independent sources emit electric fields with random phases. In particular, we evaluate third-order correlations among output intensities as a function of the delays, and show how the presence of a correlation revival for small delays cannot be explained by the classical model of light. The observation of a revival is thus a nonclassicality signature, which can be achieved only by sources with a photon-number statistics that is highly sub-Poissonian. Our analysis provides strong evidence for the nonclassicality of the experiment discussed by Menssen et al. [Phys. Rev. Lett. 118, 153603 (2017), 10.1103/PhysRevLett.118.153603], and shows how a collective "triad" phase affects the interference of any three or more light fields, irrespective of their quantum or classical character.

Encapsulation of Carotenoids

NASA Astrophysics Data System (ADS)

Ribeiro, Henelyta S.; Schuchmann, Heike P.; Engel, Robert; Walz, Elke; Briviba, Karlis

Carotenoids are natural pigments, which are synthesized by microorganisms and plants. More than 600 naturally occurring carotenoids have been found in the nature. The main sources of carotenoids are fruits, vegetables, leaves, peppers, and certain types of fishes, sea foods, and birds. Carotenoids may protect cells against photosensitization and work as light-absorbing pigments during photosynthesis. Some carotenoids may inhibit the destructive effect of reactive oxygen species. Due to the antioxidative properties of carotenoids, many investigations regarding their protective effects against cardiovascular diseases and certain types of cancers, as well as other degenerative illnesses, have been carried out in the last years (Briviba et al. 2004; Krinsky et al. 2004; Kirsh et al. 2006). A diet rich in carotenoids may also contribute to photoprotection against UV radiation (Stahl et al. 2006). In vitro studies have shown that carotenoids such as β-cryptoxanthin and lycopene stimulate bone formation and mineralization. The results may be related to prevention of osteoporosis (Kim et al. 2003; Yamaguchi and Uchiyama 2003; 2004; Yamaguchi et al. 2005).

BRITE-Constellation reveals evidence for pulsations in the enigmatic binary η Carinae

NASA Astrophysics Data System (ADS)

Richardson, Noel D.; Pablo, Herbert; Sterken, Christiaan; Pigulski, Andrzej; Koenigsberger, Gloria; Moffat, Anthony F. J.; Madura, Thomas I.; Hamaguchi, Kenji; Corcoran, Michael F.; Damineli, Augusto; Gull, Theodore R.; Hillier, D. John; Weigelt, Gerd; Handler, Gerald; Popowicz, Adam; Wade, Gregg A.; Weiss, Werner W.; Zwintz, Konstanze

2018-04-01

η Car is a massive, eccentric binary with a rich observational history. We obtained the first high-cadence, high-precision light curves with the BRITE-Constellation nanosatellites over 6 months in 2016 and 6 months in 2017. The light curve is contaminated by several sources including the Homunculus nebula and neighbouring stars, including the eclipsing binary CPD -59°2628. However, we found two coherent oscillations in the light curve. These may represent pulsations that are not yet understood but we postulate that they are related to tidally excited oscillations of η Car's primary star, and would be similar to those detected in lower mass eccentric binaries. In particular, one frequency was previously detected by van Genderen et al. and Sterken et al. through the time period of 1974-1995 through timing measurements of photometric maxima. Thus, this frequency seems to have been detected for nearly four decades, indicating that it has been stable in frequency over this time span. These pulsations could help provide the first direct constraints on the fundamental parameters of the primary star if confirmed and refined with future observations.

VLA Measurements of Faraday Rotation through Coronal Mass Ejections

NASA Astrophysics Data System (ADS)

Kooi, Jason E.; Fischer, Patrick D.; Buffo, Jacob J.; Spangler, Steven R.

2017-04-01

Coronal mass ejections (CMEs) are large-scale eruptions of plasma from the Sun, which play an important role in space weather. Faraday rotation is the rotation of the plane of polarization that results when a linearly polarized signal passes through a magnetized plasma such as a CME. Faraday rotation is proportional to the path integral through the plasma of the electron density and the line-of-sight component of the magnetic field. Faraday-rotation observations of a source near the Sun can provide information on the plasma structure of a CME shortly after launch. We report on simultaneous white-light and radio observations made of three CMEs in August 2012. We made sensitive Very Large Array (VLA) full-polarization observations using 1 - 2 GHz frequencies of a constellation of radio sources through the solar corona at heliocentric distances that ranged from 6 - 15 R_{⊙}. Two sources (0842+1835 and 0900+1832) were occulted by a single CME, and one source (0843+1547) was occulted by two CMEs. In addition to our radioastronomical observations, which represent one of the first active hunts for CME Faraday rotation since Bird et al. ( Solar Phys., 98, 341, 1985) and the first active hunt using the VLA, we obtained white-light coronagraph images from the Large Angle and Spectrometric Coronagraph (LASCO) C3 instrument to determine the Thomson-scattering brightness [BT], providing a means to independently estimate the plasma density and determine its contribution to the observed Faraday rotation. A constant-density force-free flux rope embedded in the background corona was used to model the effects of the CMEs on BT and Faraday rotation. The plasma densities (6 - 22×103 cm^{-3}) and axial magnetic-field strengths (2 - 12 mG) inferred from our models are consistent with the modeling work of Liu et al. ( Astrophys. J., 665, 1439, 2007) and Jensen and Russell ( Geophys. Res. Lett., 35, L02103, 2008), as well as previous CME Faraday-rotation observations by Bird et al. (1985).

Passive decoy-state quantum key distribution with practical light sources

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

Curty, Marcos; Ma, Xiongfeng; Qi, Bing

2010-02-15

Decoy states have been proven to be a very useful method for significantly enhancing the performance of quantum key distribution systems with practical light sources. Although active modulation of the intensity of the laser pulses is an effective way of preparing decoy states in principle, in practice passive preparation might be desirable in some scenarios. Typical passive schemes involve parametric down-conversion. More recently, it has been shown that phase-randomized weak coherent pulses (WCP) can also be used for the same purpose [M. Curty et al., Opt. Lett. 34, 3238 (2009).] This proposal requires only linear optics together with a simplemore » threshold photon detector, which shows the practical feasibility of the method. Most importantly, the resulting secret key rate is comparable to the one delivered by an active decoy-state setup with an infinite number of decoy settings. In this article we extend these results, now showing specifically the analysis for other practical scenarios with different light sources and photodetectors. In particular, we consider sources emitting thermal states, phase-randomized WCP, and strong coherent light in combination with several types of photodetectors, like, for instance, threshold photon detectors, photon number resolving detectors, and classical photodetectors. Our analysis includes as well the effect that detection inefficiencies and noise in the form of dark counts shown by current threshold detectors might have on the final secret key rate. Moreover, we provide estimations on the effects that statistical fluctuations due to a finite data size can have in practical implementations.« less

Synthesis and luminescent properties of Tb3Al5O12:Ce3+ phosphors for warm white light emitting diodes

NASA Astrophysics Data System (ADS)

Meng, Qinghuan; Liu, Ying; Fu, Yujie; Zu, Yuangang; Zhou, Zhenbao

2018-01-01

A series of Tb3Al5O12:Ce3+ phosphors were successfully synthesized by a precipitation method. The pure Tb3Al5O12 phase was obtained in the synthesized Tb3Al5O12:Ce3+ phosphors after heat treatments at 500 °C in air for 3 h. The excitation spectra of Tb3Al5O12:Ce3+ phosphors include excitation bands corresponding to Tb3+ and Ce3+ ions. Under the excitation at 455 nm, Tb3Al5O12:Ce3+ phosphors show emission band at around 553 nm. The critical doping concentration of Ce3+ in Tb3Al5O12 is 6mol%, which shows the highest emission intensity. White light-emitting diodes were fabricated by combining InGaN-based blue light-emitting diodes with Tb3Al5O12:Ce3+ and Y3Al5O12:Ce3+ phosphors. The Tb3Al5O12:Ce3+ based white light-emitting diode shows a lower color temperature than that of Y3Al5O12:Ce3+ based white light-emitting diode. The experimental results clearly indicate that the prepared Tb3Al5O12:Ce3+ has potential applications in white light emitting diodes.

Chloroplast and reactive oxygen species involvement in apoptotic-like programmed cell death in Arabidopsis suspension cultures

PubMed Central

Doyle, Siamsa M.; Diamond, Mark; McCabe, Paul F.

2010-01-01

Chloroplasts produce reactive oxygen species (ROS) during cellular stress. ROS are known to act as regulators of programmed cell death (PCD) in plant and animal cells, so it is possible that chloroplasts have a role in regulating PCD in green tissue. Arabidopsis thaliana cell suspension cultures are model systems in which to test this, as here it is shown that their cells contain well-developed, functional chloroplasts when grown in the light, but not when grown in the dark. Heat treatment at 55 °C induced apoptotic-like (AL)-PCD in the cultures, but light-grown cultures responded with significantly less AL-PCD than dark-grown cultures. Chloroplast-free light-grown cultures were established using norflurazon, spectinomycin, and lincomycin and these cultures responded to heat treatment with increased AL-PCD, demonstrating that chloroplasts affect AL-PCD induction in light-grown cultures. Antioxidant treatment of light-grown cultures also resulted in increased AL-PCD induction, suggesting that chloroplast-produced ROS may be involved in AL-PCD regulation. Cycloheximide treatment of light-grown cultures prolonged cell viability and attenuated AL-PCD induction; however, this effect was less pronounced in dark-grown cultures, and did not occur in antioxidant-treated light-grown cultures. This suggests that a complex interplay between light, chloroplasts, ROS, and nuclear protein synthesis occurs during plant AL-PCD. The results of this study highlight the importance of taking into account the time-point at which cells are observed and whether the cells are light-grown and chloroplast-containing or not, for any study on plant AL-PCD, as it appears that chloroplasts can play a significant role in AL-PCD regulation. PMID:19933317

Dynamic light scattering measurements of mutual diffusion coefficients of water-rich 2-butoxyethanol/water systems

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

Bender, T.M.; Pecora, R.

1988-03-24

The mutual diffusion coefficients of the water-rich region of the 2-butoxyethanol (BE)water system were measured by dynamic light scattering at 10, 25, and 40/sup 0/C. At mole fraction of BE greater than 0.02 (X/sub BE/ greater than or equal to 0.02), the results were in good agreement with the work of T. Kato. Below X/sub BE/ = 0.02 an anomalous diffusion region appeared with particles of apparent hydrodynamic radius of up to 1000 A being observed in agreement with the work of S. Kato et al. Further investigations using BE from different sources did not show the anomalous diffusion regionmore » and indicate that the possible presence of small amounts of contaminants in the BE is the source of this anomalous diffusion data« less

Calibration of a microchannel plate based extreme ultraviolet grazing incident spectrometer at the Advanced Light Source

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

Bakeman, M. S.; Lawrence Berkeley National Laboratory, Berkeley, California 94720; Tilborg, J. van

We present the design and calibration of a microchannel plate based extreme ultraviolet spectrometer. Calibration was performed at the Advance Light Source (ALS) at the Lawrence Berkeley National Laboratory (LBNL). This spectrometer will be used to record the single shot spectrum of radiation emitted by the tapered hybrid undulator (THUNDER) undulator installed at the LOASIS GeV-class laser-plasma-accelerator. The spectrometer uses an aberration-corrected concave grating with 1200 lines/mm covering 11-62 nm and a microchannel plate detector with a CsI coated photocathode for increased quantum efficiency in the extreme ultraviolet. A touch screen interface controls the grating angle, aperture size, and placementmore » of the detector in vacuum, allowing for high-resolution measurements over the entire spectral range.« less

InGaAsN/GaAs Heterostructures for Long-Wavelength Light-Emitting Devices

DTIC Science & Technology

2000-06-23

vertical cavity surface emitting lasers ( VCSELs ) on GaAs is expected to be possible by... molecular beam epitaxy using an RF plasma-source. Broad area and ridge waveguide laser structures based on such QWs exhibit performance that can...work with GaAs/AlAs DBR-mirrors is expected to lead to novel vertical cavity lasers for optical fiber communication systems. Acknowledgement

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

Tracy, Jennifer; Jacobson, Arne; Mills, Evan

Flashlight usage is widespread across much of sub-Saharan Africa.1 In Kenya in particular, over half of all households report owning a flashlight (Kamfor, 2002). Aside from household use, flashlights are also widely used to perform income-earning jobs in Kenya. Lumina Research Note No.4, the first report in this series documenting flashlight use in Kenya, highlights flashlight use patterns of night watchmen and bicycle taxi drivers. Both of these are occupations that rely on the use of flashlights on a nightly basis (Tracy et al., 2009). Also highlighted by Research Note No.4, flashlight users in Kenya have reported being highly dissatisfiedmore » with the quality of the low-cost LED flashlights that are available, and they identify several reoccurring problems they have faced as flashlight end-users (Tracy et al., 2009). The fact that there exists a substantial dependency upon flashlights in Kenya and that users are disgruntled with the available products suggests reasons for concern about flashlight quality. This concern is present despite two recent technological transitions in the flashlight market. First, LED technology has quickly emerged as the dominant source of portable lighting in Kenya, outpacing incandescent flashlights (Johnstone et al., 2009). LED technology has the potential to provide efficiency and performance benefits relative to incandescent bulbs, and low-cost LEDs have achieved price levels that make them cost competitive with conventional lighting sources for a number of applications (Mills, 2005). Second, rechargeable sealed-lead acid (SLA) batteries are also becoming more prevalent alternatives to disposable dry cell batteries. Flashlights using rechargeable SLA batteries tend to have a lower total cost of ownership over a two-year period than a flashlight using dry cell batteries (Radecsky, 2009); however, as this current report highlights, this may vary depending on the intensity of use patterns. To avoid a potential market spoiling effect for off-grid lighting products based on LED technology (Mills and Jacobson, 2008; Lighting Africa, 2007) a better understanding of flashlight use-patterns is crucial (Tracy et al., 2009). In addition, the economic implications faced by rural flashlight end-users provide further incentive for a move toward higher quality low-cost flashlights. In this report, our team uses interviews with 46 end users of flashlights to collect information about their use patterns and costs associated with owning and operating flashlight products. While flashlights used in their portable mode typically do not represent a substitute for kerosene or other forms of fuel-based lighting, at times they are used in stationary applications in place of a fuel-based lamp. In either case, these products often represent end users first exposure to LED technology and rechargeable dry cell batteries, and thus stand to either provide a positive or negative impression of these technologies for a diversity of lighting applications.« less

Toward in situ x-ray diffraction imaging at the nanometer scale

NASA Astrophysics Data System (ADS)

Zatsepin, Nadia A.; Dilanian, Ruben A.; Nikulin, Andrei Y.; Gable, Brian M.; Muddle, Barry C.; Sakata, Osami

2008-08-01

We present the results of preliminary investigations determining the sensitivity and applicability of a novel x-ray diffraction based nanoscale imaging technique, including simulations and experiments. The ultimate aim of this nascent technique is non-destructive, bulk-material characterization on the nanometer scale, involving three dimensional image reconstructions of embedded nanoparticles and in situ sample characterization. The approach is insensitive to x-ray coherence, making it applicable to synchrotron and laboratory hard x-ray sources, opening the possibility of unprecedented nanometer resolution with the latter. The technique is being developed with a focus on analyzing a technologically important light metal alloy, Al-xCu (where x is 2.0-5.0 %wt). The mono- and polycrystalline samples contain crystallographically oriented, weakly diffracting Al2Cu nanoprecipitates in a sparse, spatially random dispersion within the Al matrix. By employing a triple-axis diffractometer in the non-dispersive setup we collected two-dimensional reciprocal space maps of synchrotron x-rays diffracted from the Al2Cu nanoparticles. The intensity profiles of the diffraction peaks confirmed the sensitivity of the technique to the presence and orientation of the nanoparticles. This is a fundamental step towards in situ observation of such extremely sparse, weakly diffracting nanoprecipitates embedded in light metal alloys at early stages of their growth.

An experimental study on ferrous iron photo-oxidation: Effect of the solar spectrum on the surface for acidification of surface water in the early Hesperian Mars

NASA Astrophysics Data System (ADS)

Tabata, H.; Sekine, Y.; Kanzaki, Y.; Sugita, S.; Murakami, T.

2017-12-01

Geochemical evidence obatined by Mars Opportunity rover suggests that the pH of Martian surface water shifted to highly acidic, i.e., pH 2-4, in the early Hesperian (e.g., Tosca et al., 2005). Hurowitz et al. (2010) proposed that solar UV light may have promoted the acidification through photo-oxidation of ferrous iron dissolved in upwelling groundwater on early Mars. However, the trigger for the acidification in the early Hesperian remains unclear. The photo-oxidation of Fe2+ occurs under acidic conditions, i.e., pH < 3 (Jortner et al., 1962); however, the pH of upwelling groundwater would be neutral to alkaline (Zolotov et al., 2016). At neutral to alkaline pH, FeOH+ can exist together with Fe2+ in a solution. While both Fe2+ and FeOH+ are photo-oxidized only by UV light (< 300 nm), FeOH+ can also be photo-oxidized by long UV/visible light (300-400 nm). Thus, the efficiency of acidification through photo-oxidation on early Mars should have depended on the solar spectrum on the surface at that time which is determined by the atmospheric composition. To investigate the effect of UV spectrum on the acidification, we conducted two types of laboratory experiments: One used a Xe lamp as the light source for photo-oxidation of ferrous iron to irradiate light with continuous spectrum from 250 to 400 nm, and the other used the Xe lamp with an optical filter that cuts off UV light shorter than 300 nm. The pH value of the starting solution was around 7. Upon the UV irradiation covering full wavelength range (250-400 nm), the pH value of the solution decreases down to less than 4, consistent with the proposed pH of the Hesperian acidic water on Meridiani Planum (Tosca et al., 2005). This occurs because Fe2+ is stable at pH < 5, and because Fe2+ can be continuously photo-oxidized in the acidic solution by UV light in 250-300 nm. When the UV irradiation covering 300-400 nm, the pH value of the solution also decreases to pH 5 immediately after the UV irradiation. However, it does not decrease less than pH 5 and reaches a steady state. This is the case because FeOH+ is converted into Fe2+ at low pH, which prevents further photo-oxidation by light in 300-400 nm. These results suggest that a change in the atmospheric composition and consequent reaching of UV light in the wavelength < 300 nm may have played a key role for triggering the acidification in the early Hesperian.

Geochemical investigation of Archaean Bimodal and Dwalile metamorphic suites, Ancient Gneiss Complex, Swaziland

USGS Publications Warehouse

Hunter, D.R.; Barker, F.; Millard, H.T.

1984-01-01

The bimodal suite (BMS) comprises leucotonalitic and trondhjemitic gneisses interlayered with amphibolites. Based on geochemical parameters three main groups of siliceous gneiss are recognized: (i) SiO2 14%, and fractionated light rare-earth element (REE) and flat heavy REE patterns; (ii) SiO2 and Al2O3 contents similar to (i) but with strongly fractionated REE patterns with steep heavy REE slopes; (iii) SiO2 > 73%, Al2O3 < 14%, Zr ??? 500 ppm and high contents of total REE having fractionated light REE and flat heavy REE patterns with large negative Eu anomalies. The interlayered amphibolites have major element abundances similar to those of basaltic komatiites, Mg-tholeiites and Fe-rich tholeiites. The former have gently sloping REE patterns, whereas the Mg-tholeiites have non-uniform REE patterns ranging from flat (??? 10 times chondrite) to strongly light REE-enriched. The Fe-rich amphibolites have flat REE patterns at 20-30 times chondrite. The Dwalile metamorphic suite, which is preserved in the keels of synforms within the BMS, includes peridotitic komatiites that have depleted light REE patterns similar to those of compositionally similar volcanics in the Onverwacht Group, Barberton, basaltic komatiites and tholeiites. The basaltic komatiites have REE patterns parallel to those of the BMS basaltic komatiites but with lower total REE contents. The Dwalile tholeiites have flat REE patterns. The basic and ultrabasic liquids were derived by partial melting of a mantle source which may have been heterogeneous or the heterogeneity may have resulted from sequential melting of the mantle source. The Fe-rich amphibolites were derived either from liquids generated at shallow levels or from liquids generated at depth which subsequently underwent extensive fractionation. ?? 1984.

VizieR Online Data Catalog: M67 variable stars from Kepler/K2-Campaign-5 (Gonzalez, 2016)

NASA Astrophysics Data System (ADS)

Gonzalez, G.

2017-06-01

M 67 was observed continuously between 2015 April 27 and July 10 during the Kepler/K2-Campaign-5 (hereafter, 'Campaign-5 field'). It includes 28 850 long-cadence, 204 short-cadence, and several other special targets. Several data products for the Campaign-5 field were released to the public on the NASA Barbara A. Mikulski Archive for Space Telescopes (MAST) website on 2015 October 30 (https://archive.stsci.edu/k2/). We downloaded tar files containing all the long-cadence light-curve (CLC) files of the Campaign-5 targets from the MAST archive. In addition, we downloaded the comprehensive K2 input catalogue (EPIC) for the Campaign-5 field. We supplemented the NASA K2 data with ground-based data, of which Nardiello et al. (2016, Cat. J/MNRAS/455/2337) is our primary source. Nardiello et al. (2016, Cat. J/MNRAS/455/2337) list the positions and white-light magnitudes for 6905 objects in the M 67 field, but they only list BVRI magnitudes, proper motions and membership probabilities for a subset of this large sample. Cross-referencing (using coordinates) the Campaign-5 input catalogue with the Nardiello et al. (2016, Cat. J/MNRAS/455/2337) catalogue resulted in 3201 matches. Of these, 639 have light curves available in the MAST Campaign-5 archive. This will be the working sample. (1 data file).

Response to Lisovski et al.

USGS Publications Warehouse

Streby, Henry M.; Kramer, Gunnar R.; Peterson, Sean M.; Lehman, Justin A.; Buehler, David A.; Andersen, David

2018-01-01

Lisovski et al. [1] describe the widely recognized limitations of light-level geolocator data for identifying short-distance latitudinal movements, recommend that caution be used when interpreting such data, intimated that we did not use such caution and argued that environmental shading likely explained the Golden-winged Warbler (Vermivora chrysoptera) movements described in our 2015 report [2] . Lisovski et al. [1] conclude that the bird movements we reported could not be disentangled from estimation error in stationary animals caused by environmental shading. We argue that, to the contrary, these hypotheses can easily be disentangled because the premise that environmental shading caused synchronous and parallel error among geolocators is false. With their assertion that our location estimates could be biased by >3,500 km on a day with no observable local sources of shading, Lisovski et al. [1] have taken a position of incredulity toward all geolocator-based animal movement data published to date.

A forensic hypothesis for the mystery of al-Hasan’s death in the 7th century: Mercury(I) chloride intoxication

PubMed Central

Burke, Nicole; Golas, Mitchell; Raafat, Cyrus L.

2015-01-01

The puzzle of a mysterious death in the Middle Ages has been hypothesized in terms of contemporary forensic legal and scientific methods. That al-Hasan ibn-‘Ali died in 669 aged just 45 has been forensically analyzed based on written sources that dictate eyewitness accounts of historical events. The report of the contemporaneous poisoning of another individual who resided under the same household as al-Hasan’s and experienced similar, yet non-lethal, symptoms has served as the beginning of the analysis. In light of ancient (medieval) documents and through using mineralogical, medical, and chemical facts, it has been hypothesized that mineral calomel (mercury(I) chloride, Hg2Cl2) from a certain region in the Byzantine Empire (present-day western Turkey) was the substance primarily responsible for the murder of al-Hasan. PMID:26377933

Rare-earth element geochemistry and the origin of andesites and basalts of the Taupo Volcanic Zone, New Zealand

USGS Publications Warehouse

Cole, J.W.; Cashman, K.V.; Rankin, P.C.

1983-01-01

Two types of basalt (a high-Al basalt associated with the rhyolitic centres north of Taupo and a "low-Al" basalt erupted from Red Crater, Tongariro Volcanic Centre) and five types of andesite (labradorite andesite, labradorite-pyroxene andesite, hornblende andesite, pyroxene low-Si andesite and olivine andesite/low-Si andesite) occur in the Taupo Volcanic Zone (TVZ), North Island, New Zealand. Rare-earth abundances for both basalts and andesites are particularly enriched in light rare-earth elements. High-Al basalts are more enriched than the "low-Al" basalt and have values comparable to the andesites. Labradorite and labradorite-pyroxene andesites all have negative Eu anomalies and hornblende andesites all have negative Ce anomalies. The former is probably due to changing plagioclase composition during fractionation and the latter to late-stage hydration of the magma. Least-squares mixing models indicate that neither high-Al nor "low-Al" basalts are likely sources for labradorite/labradorite-pyroxene andesites. High-Al basalts are considered to result from fractionation of olivine and clinopyroxene from a garnet-free peridotite at the top of the mantle wedge. Labradorite/labradorite-pyroxene andesites are mainly associated with an older NW-trending arc. The source is likely to be garnet-free but it is not certain whether the andesites result from partial melting of the top of the subducting plate or a hydrated lower portion of the mantle wedge. Pyroxene low-Si andesites probably result from cumulation of pyroxene and calcic plagioclase within labradorite-pyroxene andesites, and hornblende andesites by late-stage hydration of labradorite-pyroxene andesite magma. Olivine andesites, low-Si andesites and "low-Al" basalts are related to the NNE-trending Taupo-Hikurangi arc structure. Although the initial source material is different for these lavas they have probably undergone a similar history to the labradorite/labradorite-pyroxene andesites. All lavas show evidence of crustal contamination. ?? 1983.

Plume magmatism and crustal growth at 2.9 to 3.0 Ga in the Steep Rock and Lumby Lake area, Western Superior Province

NASA Astrophysics Data System (ADS)

Tomlinson, K. Y.; Hughes, D. J.; Thurston, P. C.; Hall, R. P.

1999-01-01

The greenstone belts of the western Superior Province are predominantly 2.78 to 2.69 Ga and provide evidence of oceanic and arc volcanism during the accretionary phase of development of the Superior Province. There is also scattered evidence of Meso-Archean crust (predominantly 2.9 to 3.0 Ga) within the western Superior Province. The Meso-Archean greenstone belts commonly contain platformal sediments and unconformably overlie granitoid basement. The platformal sediments occur associated with komatiitic and tholeiitic volcanic rocks that suggest a history of magmatism associated with rifting during the Meso-Archean. The central Wabigoon Subprovince is a key area of Meso-Archean crust and in its southern portion comprises the Steep Rock, Finlayson and Lumby Lake greenstone belts. The Steep Rock greenstone belt unconformably overlies 3 Ga continental basement and contains platformal sediments succeeded by komatiitic and tholeiitic volcanic rocks. The Lumby Lake greenstone belt contains thick sequences of mafic volcanics, a number of komatiite horizons, and thin platformal sedimentary units. The two belts are joined by the predominantly mafic volcanic Finlayson greenstone belt. The volcanics throughout these three greenstone belts may be correlated to some extent and a range of basaltic and komatiite types is present. Al-undepleted komatiites present in the Lumby Lake greenstone belt have an Al 2O 3/TiO 2 ratio ranging from 14 to 27 and (Gd/Yb) N from 0.7 to 1.3. These are divided into basaltic komatiites with generally unfractionated mantle-normalised multi-element profiles, and spinifex-textured high-Mg basalts with slightly light REE enriched multi-element profiles and small negative Nb and Ta anomalies. The unfractionated basaltic komatiites represent high degree partial melts of the upper mantle whereas the spinifex-textured high-Mg basalts represent evolutionary products of the komatiite liquids following olivine and chromite fractionation and crustal contamination. Al-depleted komatiites are present in both the Lumby Lake and Steep Rock belts and have Al 2O 3/TiO 2 ratio ranges from 2.5 to 5. These display strong enrichment in the light REE and Nb and strong depletion in the heavy REE and Y ((Gd/Yb) N=2-4). They represent a deep mantle plume source generated from a high degree of partial melting in the majorite garnet stability field. The basaltic flows in all three greenstone belts are predominantly slightly light REE depleted and represent a slightly depleted upper mantle source. Basalts spatially associated with the unfractionated basaltic komatiites and the slightly light REE enriched spinifex-textured high-Mg basalts are also slightly enriched in light REE and have negative Nb and Ta anomalies. These basalts represent evolved products of the primitive basaltic komatiites and enriched spinifex-textured high-Mg basalts after further crustal contamination and olivine and clinopyroxene fractionation. The geochemical stratigraphy in the Lumby Lake belt is consistent with an ascending mantle plume model. The light REE depleted basalts were derived from upper mantle melted by an ascending mantle plume. These are overlain by the unfractionated basaltic komatiites and their evolutionary products which represent hotter plume head material derived from a mixture of plume mantle and entrained depleted upper mantle. In turn, these are overlain by strongly light REE and HFSE enriched komatiites that represent a deep plume source that has not been mixed with depleted mantle and are, therefore, likely to have been derived from a plume core or tail. Volcanism was protracted in these three greenstone belts lasting ca. 70 Ma and combined stratigraphic evidence from the Lumby Lake and Steep Rock belts suggests that more than one plume may have ascended and tapped the same mantle sources, over time, within the area. Plume magmatism and rifting of continental platforms thus appears to have been an important feature of crustal development in the Meso-Archean.

Advanced light source: Compendium of user abstracts and technical reports,1993-1996

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

None, None

1997-04-01

This compendium contains abstracts written by users summarizing research completed or in progress from 1993-1996, ALS technical reports describing ongoing efforts related to improvement in machine operations and research and development projects, and information on ALS beamlines planned through 1998. Two tables of contents organize the user abstracts by beamline and by area of research, and an author index makes abstracts accessible by author and by principal investigator. Technical details for each beamline including whom to contact for additional information can be found in the beamline information section. Separate abstracts have been indexed into the database for contributions to thismore » compendium.« less

Environmental insults: critical triggers for amyotrophic lateral sclerosis.

PubMed

Yu, Bing; Pamphlett, Roger

2017-01-01

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease characterised by a rapid loss of lower and upper motor neurons. As a complex disease, the ageing process and complicated gene-environment interactions are involved in the majority of cases. Significant advances have been made in unravelling the genetic susceptibility to ALS with massively parallel sequencing technologies, while environmental insults remain a suspected but largely unexplored source of risk. Several studies applying the strategy of Mendelian randomisation have strengthened the link between environmental insults and ALS, but none so far has proved conclusive. We propose a new ALS model which links the current knowledge of genetic factors, ageing and environmental insults. This model provides a mechanism as to how ALS is initiated, with environmental insults playing a critical role. The available evidence has suggested that inherited defect(s) could cause mitochondrial dysfunction, which would establish the primary susceptibility to ALS. Further study of the underlying mechanism may shed light on ALS pathogenesis. Environmental insults are a critical trigger for ALS, particularly in the aged individuals with other toxicant susceptible genes. The identification of ALS triggers could lead to preventive strategies for those individuals at risk.

Substrate dependence of TM-polarized light emission characteristics of BAlGaN/AlN quantum wells

NASA Astrophysics Data System (ADS)

Park, Seoung-Hwan; Ahn, Doyeol

2018-06-01

To study the substrate dependence of light emission characteristics of transverse-magnetic (TM)-polarized light emitted from BAlGaN/AlN quantum wells (QWs) grown on GaN and AlN substrates were investigated theoretically. It is found that the topmost valence subband for QW structures grown on AlN substrate, is heavy hole state (HH1) while that for QW structures grown on GaN substrate is crystal-field split off light hole state (CL1), irrespective of the boron content. Since TM-polarized light emission is associated with the light hole state, the TM-polarized emission peak of BAlGaN/AlN QW structures grown on GaN substrate is expected to be much larger than that of the QW structure grown on AlN substrate. Also, both QW structures show that the spontaneous emission peak of BAlGaN/AlN QW structures would be improved with the inclusion of the boron. However, it rapidly begins to decrease when the boron content exceeds a critical value.

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).

Deformation processed Al/Ca nano-filamentary composite conductors for HVDC applications

NASA Astrophysics Data System (ADS)

Czahor, C. F.; Anderson, I. E.; Riedemann, T. M.; Russell, A. M.

2017-07-01

Efficient long-distance power transmission is necessary as the world continues to implement renewable energy sources, often sited in remote areas. Light, strong, high-conductivity materials are desirable for this application to reduce both construction and operational costs. In this study an Al/Ca (11.5% vol.) composite with nano-filamentary reinforcement was produced by powder metallurgy then extruded, swaged, and wire drawn to a maximum true strain of 12.7. The tensile strength increased exponentially as the filament size was reduced to the sub-micron level. In an effort to improve the conductor’s ability to operate at elevated temperatures, the deformation-processed wires were heat-treated at 260°C to transform the Ca-reinforcing filaments to Al2Ca. Such a transformation raised the tensile strength by as much as 28%, and caused little change in ductility, while the electrical conductivity was reduced by only 1% to 3%. Al/Al2Ca composites are compared to existing conductor materials to show how implementation could affect installation and performance.

Development of GaN-based microchemical sensor nodes

NASA Technical Reports Server (NTRS)

Prokopuk, Nicholas; Son, Kyung-Ah; George, Thomas; Moon, Jeong S.

2005-01-01

Sensors based III-N technology are gaining significant interest due to their potential for monolithic integration of RF transceivers and light sources and the capability of high temperature operations. We are developing a GaN-based micro chemical sensor node for remote detection of chemical toxins, and present electrical responses of AlGaN/GaN HEMT (High Electron Mobility Transistor) sensors to chemical toxins as well as other common gases.

Multilayer deposition and EUV reflectance characterization of 131 ? flight mirrors for AIA at LLNL

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

Soufli, R; Robinson, J C; Spiller, E

2006-02-22

Mo/Si multilayer coatings reflecting at 131 {angstrom} were deposited successfully on the AIA primary and secondary flight mirrors and on two coating witness Si wafers, on November 16, 2005, at LLNL. All coatings were characterized by means of EUV reflectance measurements at beamline 6.3.2 of the Advanced Light Source (ALS) synchrotron at LBNL, and were found to be well within specifications.

Highly-reliable operation of 638-nm broad stripe laser diode with high wall-plug efficiency for display applications

NASA Astrophysics Data System (ADS)

Yagi, Tetsuya; Shimada, Naoyuki; Nishida, Takehiro; Mitsuyama, Hiroshi; Miyashita, Motoharu

2013-03-01

Laser based displays, as pico to cinema laser projectors have gathered much attention because of wide gamut, low power consumption, and so on. Laser light sources for the displays are operated mainly in CW, and heat management is one of the big issues. Therefore, highly efficient operation is necessitated. Also the light sources for the displays are requested to be highly reliable. 638 nm broad stripe laser diode (LD) was newly developed for high efficiency and highly reliable operation. An AlGaInP/GaAs red LD suffers from low wall plug efficiency (WPE) due to electron overflow from an active layer to a p-cladding layer. Large optical confinement factor (Γ) design with AlInP cladding layers is adopted to improve the WPE. The design has a disadvantage for reliable operation because the large Γ causes high optical density and brings a catastrophic optical degradation (COD) at a front facet. To overcome the disadvantage, a window-mirror structure is also adopted in the LD. The LD shows WPE of 35% at 25°C, highest record in the world, and highly stable operation at 35°C, 550 mW up to 8,000 hours without any catastrophic optical degradation.

Probing Complexity using the LCLS and the ALS

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

Berrah, Nora

The goal of our research program is to investigate fundamental interactions between photons and molecular/nano-systems to advance our quantitative understanding of electron correlations, charge transfer and many body phenomena. Our research projects focus on probing, on a femtosecond time-scale, multi-electron interactions and tracing nuclear motion in order to understand, and ultimately control energy flow and charge transfer processes from electromagnetic radiation to matter. The experiments will be carried out with state of the art instrumentation built by the P.I. team with funds from a DoE "Single Investigator and Small Group Research" (SISGR) grant. The research projects carried out the pastmore » three years consisted of first experiments using the linac coherent light source (LCLS) x-ray free electron laser (FEL) facility at the SLAC National Laboratory, as well as the study of correlated processes in select anions using the ALS. A report for the past cycle is described in section II. These studies have paved the way for our renewal application for the next three years. Our research interests for the next three years extend our past and present research by carrying out time-resolved measurements described in section III. They will consist of: a) The study of molecular dynamics that happen on ultrafast time scales, using pump-probe schemes and the study of non-linear physics in the x-ray regime via multi-photon absorption from the LCLS. This will be achieved by measuring and examining both electronic and nuclear dynamics subsequent to the interaction of molecules and nano-systems with LCLS pulses of various wavelength, intensity and pulse duration as described in section III.A. b) The study of molecular dynamics and correlated processes via absorption of vuv-soft x-rays from the Advanced Light Source (ALS) at Lawrence Berkeley Laboratory to provide single-photon ionization baseline results for LCLS studies. In addition, we will study the photodetachment of anions using the ALS as described in section III. B. The PI has an ALS approved program (AP) thus has guaranteed beamtime. Our research underpins several aspects of the DOE mission since our investigations of the formation and evolution of energized states in molecules and nanostructures provides a fundamental basis for understanding elementary processes in solar energy conversion and radiation-induced chemistry. Most of our work is carried out in a strong partnership with theorists. Our proposed work falls in the class of research reported to be timely and necessary by the 2013 DoE Basic Energy Sciences Advisory Committee (BESAC) Subcommittee report on Future X-ray Light Sources. Specifically, our proposed experiments fall in the category labeled class II, “Spectroscopy and Dynamics with FELs”.« less

Explaining the variability of Photochemical Reflectance Index (PRI): deconvolution of variability related to Light Use Efficiency and Canopy attributes.

NASA Astrophysics Data System (ADS)

Merlier, Elodie; Hmimina, Gabriel; Dufrêne, Eric; Soudani, Kamel

2014-05-01

The Photochemical Reflectance Index (PRI) was designed as a proxy of the state of xanthophyll cycle which is used as a response of plants to excess of light (Gamon et al., 1990; 1992). Strong relationships between PRI and LUE were shown at leaf and canopy scales and over a wide range of species (Garbulsky et al., 2011). However, its use at canopy scale was shown to be significantly hampered by effects of confounding factors such as the PRI sensitivity to leaf pigment content (Gamon et al. 2001; Nakaji et al. 2006) and to canopy structure (Hilker et al. 2008). Several approaches aimed at correcting such effects and recent works focused on the deconvolution of LUE related and LUE unrelated PRI variability (Rahimzadeh-Bajgiran et al. 2012).In this study, the PRI variability at canopy scale is investigated over two years on three species (Fagus sylvatica, Quercus robur and Pinus sylvestris) growing under two water regimes. At daily scale, PRI variability is mainly explained by radiation conditions. As already reported at leaf scale in Hmimina et al. (2014), analysis of PRI responses to incoming photosynthetically active radiation over seasonal scale allowed to separate two sources of variability : a constitutive variability mainly related to canopy structure and leaf chlorophyll content and a facultative variability mainly related to LUE and soil moisture content. These results highlight the composite nature of PRI signal measured at canopy scale and the importance of disentangling its sources of variability in order to accurately assess ecosystem light use efficiency. Gamon JA, Field CB, Bilger W, Björkman O, Fredeen AL, Peñuelas J. 1990. Remote sensing of the xanthophyll cycle and chlorophyll fluorescence in sunflower leaves and canopies. Oecologia 85, 1-7. Gamon JA, Field CB, Fredeen A AL, Thayer S. 2001. Assessing photosynthetic downregulation in sunflower stands with an optically-based model. Photosynthesis Research 67, 113-125. Gamon JA, Peñuelas J, Field CB. 1992. A narrow-waveband spectral index that tracks diurnal changes in photosynthetic efficiency. Remote Sensing of Environment 41, 35-44. Garbulsky MF, Peñuelas J, Gamon J, Inoue Y, Filella I. 2011. The photochemical reflectance index (PRI) and the remote sensing of leaf, canopy and ecosystem radiation use efficiencies: A review and meta-analysis. Remote Sensing of Environment 115, 281-297. Hilker T, Coops NC, Hall FG, Black TA, Wulder MA, Nesic Z, Krishnan P. 2008. Separating physiologically and directionally induced changes in PRI using BRDF models. Remote Sensing of Environment 112, 2777-2788. Hmimina G, Dufrêne E, Soudani K. 2014. Relationship between PRI and leaf ecophysiological and biochemical parameters under two different water statuses: toward a rapid and efficient correction method using real-time measurements. Plant, Cell & Environment 37, 2, 473-487. Nakaji T, Oguma H, Fujinuma Y. 2006. Seasonal changes in the relationship between photochemical reflectance index and photosynthetic light use efficiency of Japanese larch needles. International Journal of Remote Sensing 27, 493-509. Rahimzadeh-Bajgiran P, Munehiro M, Omasa K. 2012. Relationships between the photochemical reflectance index (PRI) and chlorophyll fluorescence parameters and plant pigment indices at different leaf growth stages. Photosynthesis Research 113, 261-271.

Physical properties of interplanetary dust: laboratory and numerical simulations

NASA Astrophysics Data System (ADS)

Hadamcik, Edith; Lasue, Jeremie; Levasseur-Regourd, Anny-Chantal; Renard, Jean-Baptiste; Buch, Arnaud; Carrasco, Nathalie; Cottin, Hervé; Fray, Nicolas; Guan, Yuan Yong; Szopa, Cyril

Laboratory light scattering measurements with the PROGRA2 experiment, in A300-CNES and ESA dedicated microgravity flights or in ground based configurations, offer an alternative to models for exploring the scattering properties of particles with structures too complex to be easily handled by computer simulations [1,2]. The technique allows the use of large size distributions (nanometers to hundreds of micrometers) and a large variety of materials, similar to those suspected to compose the interplanetary particles [3]. Asteroids are probably the source of compact particles, while comets have been shown to eject compact and fluffy materials [4]. Moreover giant planets provide further a small number of interplanetary particles. Some interstellar particles are also present. To choose the best samples and size distributions, we consider previous numerical models for the interplanetary particles and their evolution with solar distance. In this model, fluffy particles are simulated by fractal aggregates and compact particles by ellipsoids. The materials considered are silicates and carbonaceous compound. The silicate grains can be coated by the organics. Observations are fitted with two parameters: the size distribution of the particles and the ratio of silicates over carbonaceous compounds. From the light scattering properties of the particles, their equilibrium temperature can be calculated for different structures and composition. The variation of their optical properties and temperatures are studied with the heliocentric distance [5,6]. Results on analogs of cometary particles [7] and powdered meteorites as asteroidal particles will be presented and compared to numerical simulations as well as observations. Organics on cometary grains can constitute distributed sources if degraded by solar UV and heat [8, 9]. The optical properties of CxHyNz compounds are studied after thermal evolution [10]. As a first approach, they are used to simulate the evolution of cometary or interplanetary dust organics approaching the Sun. Albedo and polarization variations will be discussed. The polarization evolution will be compared to those obtained through observations [11]. Studies of the properties of our interplanetary dust cloud should provide information to better interpret observations of dust around exoplanets. Some of these planets are very close to their star. The thermal evolution of organics driven by chemical reactions will represent a fundamental knowledge to interpret the relevant polarimetric observations. We acknowledge CNES for funding the PROGRA2 experiment, CNES and ESA for the micro-gravity flights. [1] Renard J.-B. et al., Appl. Opt. 41, 609 (2002) [2] Hadamcik E. et al., In: Light scattering rev. 4, 31 (Kokhanovszky ed.), Springer -Praxis, Berlin (2009) [3] Mann I. et al., Space Sci. Rev. 110, 269 (2004) [4] Hoertz F. et al., Science 314, 716 (2006) [5] Lasue J. et al., Astron. Astrophys. 473, 641 (2007) [6] Levasseur-Regourd A.C et al., Planet Space Sci. 55, 1010 (2007) [7] Hadamcik E. et al., Icarus 190, 660 (2007) [8] Cottin H. et al., Adv. Space Res. 42, 2019 (2008) [9] Fray N. et al., Planet. Space Sci. 53, 1243 (2005) [10] Sciamma-O'Brien E. et al., Icarus, accepted [11] Levasseur-Regourd A.C., et al., In: Interplanetary dust, Gruen, Gustafson B., Dermott S., Fechtig H. (Eds), Springer, Berlin, 57 (2001)

Combustion Synthesis of Magnesium Aluminate

NASA Astrophysics Data System (ADS)

Kale, M. A.; Joshi, C. P.; Moharil, S. V.

2011-10-01

In the system MgO-Al2O3, three compounds MgAl2O4, MgAl6O10 (also expressed as- Mg0.4Al2.4O4) and MgAl26O40 are well known. Importance of the first two is well established. Magnesium aluminate (MgAl2O4) spinel is a technologically important material due to its interesting thermal properties. The MgAl2O4 ceramics also find application as humidity sensors. Apart from the luminescence studies, the interest in MgAl2O4 is due to various applications such as humidity-sensing and PEM fuel cells, TL/OSL dosimetry of the ionizing radiations, white light source. Interest in the MgAl6O10 has aroused due to possible use as a substrate for GaN growth. Attempt was made to synthesize these compounds by the combustion synthesis using metal nitrates as oxidizer and urea as a fuel. Compounds MgAl2O4 and MgAl6O10 were formed in a single step, while MgAl26O40 was not formed by this procedure. Activation of MgAl6O10 by rare earth ions like Ce3+, Eu3+ and Tb3+ and ns2 ion Pb2+ could be achieved. Excitation bands for MgAl6O10 are at slightly shorter wavelengths compared to those reported for MgAl2O4.

Machine learning and next-generation asteroid surveys

NASA Astrophysics Data System (ADS)

Nugent, Carrie R.; Dailey, John; Cutri, Roc M.; Masci, Frank J.; Mainzer, Amy K.

2017-10-01

Next-generation surveys such as NEOCam (Mainzer et al., 2016) will sift through tens of millions of point source detections daily to detect and discover asteroids. This requires new, more efficient techniques to distinguish between solar system objects, background stars and galaxies, and artifacts such as cosmic rays, scattered light and diffraction spikes.Supervised machine learning is a set of algorithms that allows computers to classify data on a training set, and then apply that classification to make predictions on new datasets. It has been employed by a broad range of fields, including computer vision, medical diagnoses, economics, and natural language processing. It has also been applied to astronomical datasets, including transient identification in the Palomar Transient Factory pipeline (Masci et al., 2016), and in the Pan-STARRS1 difference imaging (D. E. Wright et al., 2015).As part of the NEOCam extended phase A work we apply machine learning techniques to the problem of asteroid detection. Asteroid detection is an ideal application of supervised learning, as there is a wealth of metrics associated with each extracted source, and suitable training sets are easily created. Using the vetted NEOWISE dataset (E. L. Wright et al., 2010, Mainzer et al., 2011) as a proof-of-concept of this technique, we applied the python package sklearn. We report on reliability, feature set selection, and the suitability of various algorithms.

Near ultraviolet InGaN/AlGaN-based light-emitting diodes with highly reflective tin-doped indium oxide/Al-based reflectors.

PubMed

Choi, Chang-Hoon; Han, Jaecheon; Park, Jae-Seong; Seong, Tae-Yeon

2013-11-04

The enhanced light output power of a InGaN/AlGaN-based light-emitting diodes (LEDs) using three different types of highly reflective Sn-doped indium oxide (ITO)/Al-based p-type reflectors, namely, ITO/Al, Cu-doped indium oxide (CIO)/s-ITO(sputtered)/Al, and Ag nano-dots(n-Ag)/CIO/s-ITO/Al, is presented. The ITO/Al-based reflectors exhibit lower reflectance (76 - 84% at 365 nm) than Al only reflector (91.1%). However, unlike Al only n-type contact, the ITO/Al-based contacts to p-GaN show good ohmic characteristics. Near-UV (365 nm) InGaN/AlGaN-based LEDs with ITO/Al, CIO/s-ITO/Al, and n-Ag/CIO/s-ITO/Al reflectors exhibit forward-bias voltages of 3.55, 3.48, and 3.34 V at 20 mA, respectively. The LEDs with the ITO/Al and CIO/s-ITO/Al reflectors exhibit 9.5% and 13.5% higher light output power (at 20 mA), respectively, than the LEDs with the n-Ag/CIO/s-ITO/Al reflector. The improved performance of near UV LEDs is attributed to the high reflectance and low contact resistivity of the ITO/Al-based reflectors, which are better than those of conventional Al-based reflectors.

[Evaluation of visualization of biological stains with the use of alternative light source (ALS) for the purpose of genetic identification. Part I. Blood and saliva stains analysis].

PubMed

Szeremeta, Michał; Pepiński, Witold; Niemcunowicz-Janica, Anna; Skawrońska, Małgorzata; Sackiewicz, Adam; Ptaszyńska-Sarosiek, Iwona; Okłota, Magdalena

2010-01-01

The objective of the investigation was evaluation of visualization of human blood and saliva stains with the use of alternative light source for the purpose of genetic identification. Experimental bloodstains on the bright base were the most clearly seen in the natural light and white light, up to blood dilution of 1:600. Complete typeability of AmpFISTR SGM Plus kit profiles was obtained from bloodstains at dilution 1:1500. Partial AmpFISTR SGM Plus kit profiles were typed from bloodstains at dilutions 1:1750 and 1:2000. Experimental saliva stains on the light-colored base were completely invisible in the natural light and white light, while they were visualized at wavelength range 300-415 nm through yellow goggles, and at wavelength range 300-455 nm through orange goggles at saliva dilution 1: 600. Complete typeability of AmpFISTR SGM Plus kit loci was obtained from saliva stains at dilution 1:1750. Partial AmpFISTR SGM Plus kit profiles were typed from saliva stains at dilution 1:2000. The wavelength of 455 nm and orange goggles were the optimal set for visualization of bloodstains on various, noncontrasting materials. Other useful wavelength/combinations of goggles were CSS light/red goggles. In case of saliva, the most useful general condition for visualization of stains on various, non-contrasting materials was with the wavelength set to 300-415 nm, while wearing yellow goggles. Other useful combinations of wavelength/goggles were 300-455 nm/orange or red goggles, and also CSS light/orange or red goggles.

Integrated RGB laser light module for autostereoscopic outdoor displays

NASA Astrophysics Data System (ADS)

Reitterer, Jörg; Fidler, Franz; Hambeck, Christian; Saint Julien-Wallsee, Ferdinand; Najda, Stephen; Perlin, Piotr; Stanczyk, Szymon; Czernecki, Robert; McDougall, Stewart D.; Meredith, Wyn; Vickers, Garrie; Landles, Kennedy; Schmid, Ulrich

2015-02-01

We have developed highly compact RGB laser light modules to be used as light sources in multi-view autostereoscopic outdoor displays and projection devices. Each light module consists of an AlGaInP red laser diode, a GaInN blue laser diode, a GaInN green laser diode, as well as a common cylindrical microlens. The plano-convex microlens is a so-called "fast axis collimator", which is widely used for collimating light beams emitted from high-power laser diode bars, and has been optimized for polychromatic RGB laser diodes. The three light beams emitted from the red, green, and blue laser diodes are collimated in only one transverse direction, the so-called "fast axis", and in the orthogonal direction, the so-called "slow axis", the beams pass the microlens uncollimated. In the far field of the integrated RGB light module this produces Gaussian beams with a large ellipticity which are required, e.g., for the application in autostereoscopic outdoor displays. For this application only very low optical output powers of a few milliwatts per laser diode are required and therefore we have developed tailored low-power laser diode chips with short cavity lengths of 250 μm for red and 300 μm for blue. Our RGB laser light module including the three laser diode chips, associated monitor photodiodes, the common microlens, as well as the hermetically sealed package has a total volume of only 0.45 cm³, which to our knowledge is the smallest RGB laser light source to date.

Quantifying Black Carbon emissions in high northern latitudes using an Atmospheric Bayesian Inversion

NASA Astrophysics Data System (ADS)

Evangeliou, Nikolaos; Thompson, Rona; Stohl, Andreas; Shevchenko, Vladimir P.

2016-04-01

Black carbon (BC) is the main light absorbing aerosol species and it has important impacts on air quality, weather and climate. The major source of BC is incomplete combustion of fossil fuels and the burning of biomass or bio-fuels (soot). Therefore, to understand to what extent BC affects climate change and pollutant dynamics, accurate knowledge of the emissions, distribution and variation of BC is required. Most commonly, BC emission inventory datasets are built by "bottom up" approaches based on activity data and emissions factors, but these methods are considered to have large uncertainty (Cao et al, 2006). In this study, we have used a Bayesian Inversion to estimate spatially resolved BC emissions. Emissions are estimated monthly for 2014 and over the domain from 180°W to 180°E and 50°N to 90°N. Atmospheric transport is modeled using the Lagrangian Particle Dispersion Model, FLEXPART (Stohl et al., 1998; 2005), and the inversion framework, FLEXINVERT, developed by Thompson and Stohl, (2014). The study domain is of particular interest concerning the identification and estimation of BC sources. In contrast to Europe and North America, where BC sources are comparatively well documented as a result of intense monitoring, only one station recording BC concentrations exists in the whole of Siberia. In addition, emissions from gas flaring by the oil industry have been geographically misplaced in most emission inventories and may be an important source of BC at high latitudes since a significant proportion of the total gas flared occurs at these high latitudes (Stohl et al., 2013). Our results show large differences with the existing BC inventories, whereas the estimated fluxes improve modeled BC concentrations with respect to observations. References Cao, G. et al. Atmos. Environ., 40, 6516-6527, 2006. Stohl, A. et al. Atmos. Environ., 32(24), 4245-4264, 1998. Stohl, A. et al. Atmos. Chem. Phys., 5(9), 2461-2474, 2005. Stohl, A. et al. Atmos. Chem. Phys., 13, 8833-8855, 2013. Thompson, R. L., and Stohl A. Geosci. Model Dev., 7, 2223-2242, 2014.

Light interaction in sapphire/MgF2/Al triple-layer omnidirectional reflectors in AlGaN-based near ultraviolet light-emitting diodes

PubMed Central

Lee, Keon Hwa; Moon, Yong-Tae; Song, June-O; Kwak, Joon Seop

2015-01-01

This study examined systematically the mechanism of light interaction in the sapphire/MgF2/Al triple-layer omnidirectional reflectors (ODR) and its effects on the light output power in near ultraviolet light emitting diodes (NUV-LEDs) with the ODR. The light output power of NUV-LEDs with the triple-layer ODR structure increased with decreasing surface roughness of the sapphire backside in the ODR. Theoretical modeling of the roughened surface suggests that the dependence of the reflectance of the triple-layer ODR structure on the surface roughness can be attributed mainly to light absorption by the Al nano-structures and the trapping of scattered light in the MgF2 layer. Furthermore, the ray tracing simulation based upon the theoretical modeling showed good agreement with the measured reflectance of the ODR structure in diffuse mode. PMID:26010378

Light interaction in sapphire/MgF2/Al triple-layer omnidirectional reflectors in AlGaN-based near ultraviolet light-emitting diodes.

PubMed

Lee, Keon Hwa; Moon, Yong-Tae; Song, June-O; Kwak, Joon Seop

2015-05-26

This study examined systematically the mechanism of light interaction in the sapphire/MgF2/Al triple-layer omnidirectional reflectors (ODR) and its effects on the light output power in near ultraviolet light emitting diodes (NUV-LEDs) with the ODR. The light output power of NUV-LEDs with the triple-layer ODR structure increased with decreasing surface roughness of the sapphire backside in the ODR. Theoretical modeling of the roughened surface suggests that the dependence of the reflectance of the triple-layer ODR structure on the surface roughness can be attributed mainly to light absorption by the Al nano-structures and the trapping of scattered light in the MgF2 layer. Furthermore, the ray tracing simulation based upon the theoretical modeling showed good agreement with the measured reflectance of the ODR structure in diffuse mode.

Identification of nonclassical properties of light with multiplexing layouts

NASA Astrophysics Data System (ADS)

Sperling, J.; Eckstein, A.; Clements, W. R.; Moore, M.; Renema, J. J.; Kolthammer, W. S.; Nam, S. W.; Lita, A.; Gerrits, T.; Walmsley, I. A.; Agarwal, G. S.; Vogel, W.

2017-07-01

In Sperling et al. [Phys. Rev. Lett. 118, 163602 (2017), 10.1103/PhysRevLett.118.163602], we introduced and applied a detector-independent method to uncover nonclassicality. Here, we extend those techniques and give more details on the performed analysis. We derive a general theory of the positive-operator-valued measure that describes multiplexing layouts with arbitrary detectors. From the resulting quantum version of a multinomial statistics, we infer nonclassicality probes based on a matrix of normally ordered moments. We discuss these criteria and apply the theory to our data which are measured with superconducting transition-edge sensors. Our experiment produces heralded multiphoton states from a parametric down-conversion light source. We show that the known notions of sub-Poisson and sub-binomial light can be deduced from our general approach, and we establish the concept of sub-multinomial light, which is shown to outperform the former two concepts of nonclassicality for our data.

Identification of nonclassical properties of light with multiplexing layouts

PubMed Central

Sperling, J.; Eckstein, A.; Clements, W. R.; Moore, M.; Renema, J. J.; Kolthammer, W. S.; Nam, S. W.; Lita, A.; Gerrits, T.; Walmsley, I. A.; Agarwal, G. S.; Vogel, W.

2018-01-01

In Sperling et al. [Phys. Rev. Lett. 118, 163602 (2017)], we introduced and applied a detector-independent method to uncover nonclassicality. Here, we extend those techniques and give more details on the performed analysis. We derive a general theory of the positive-operator-valued measure that describes multiplexing layouts with arbitrary detectors. From the resulting quantum version of a multinomial statistics, we infer nonclassicality probes based on a matrix of normally ordered moments. We discuss these criteria and apply the theory to our data which are measured with superconducting transition-edge sensors. Our experiment produces heralded multiphoton states from a parametric down-conversion light source. We show that the known notions of sub-Poisson and sub-binomial light can be deduced from our general approach, and we establish the concept of sub-multinomial light, which is shown to outperform the former two concepts of nonclassicality for our data. PMID:29670949

Spectral optimization simulation of white light based on the photopic eye-sensitivity curve

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

Dai, Qi, E-mail: qidai@tongji.edu.cn; Institute for Advanced Study, Tongji University, 1239 Siping Road, Shanghai 200092; Key Laboratory of Ecology and Energy-saving Study of Dense Habitat

Spectral optimization simulation of white light is studied to boost maximum attainable luminous efficacy of radiation at high color-rendering index (CRI) and various color temperatures. The photopic eye-sensitivity curve V(λ) is utilized as the dominant portion of white light spectra. Emission spectra of a blue InGaN light-emitting diode (LED) and a red AlInGaP LED are added to the spectrum of V(λ) to match white color coordinates. It is demonstrated that at the condition of color temperature from 2500 K to 6500 K and CRI above 90, such white sources can achieve spectral efficacy of 330–390 lm/W, which is higher than the previously reportedmore » theoretical maximum values. We show that this eye-sensitivity-based approach also has advantages on component energy conversion efficiency compared with previously reported optimization solutions.« less

Development of at-wavelength metrology for x-ray optics at the ALS

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

Yashchuk, Valeriy V.; Goldberg, Kenneth A.; Yuan, Sheng

2010-07-09

The comprehensive realization of the exciting advantages of new third- and forth-generation synchrotron radiation light sources requires concomitant development of reflecting and diffractive x-ray optics capable of micro- and nano-focusing, brightness preservation, and super high resolution. The fabrication, tuning, and alignment of the optics are impossible without adequate metrology instrumentation, methods, and techniques. While the accuracy of ex situ optical metrology at the Advanced Light Source (ALS) has reached a state-of-the-art level, wavefront control on beamlines is often limited by environmental and systematic alignment factors, and inadequate in situ feedback. At ALS beamline 5.3.1, we are developing broadly applicable, high-accuracy,more » in situ, at-wavelength wavefront measurement techniques to surpass 100-nrad slope measurement accuracy for Kirkpatrick-Baez (KB) mirrors. The at-wavelength methodology we are developing relies on a series of tests with increasing accuracy and sensitivity. Geometric Hartmann tests, performed with a scanning illuminated sub-aperture determine the wavefront slope across the full mirror aperture. Shearing interferometry techniques use coherent illumination and provide higher sensitivity wavefront measurements. Combining these techniques with high precision optical metrology and experimental methods will enable us to provide in situ setting and alignment of bendable x-ray optics to realize diffraction-limited, sub 50 nm focusing at beamlines. We describe here details of the metrology beamline endstation, the x-ray beam diagnostic system, and original experimental techniques that have already allowed us to precisely set a bendable KB mirror to achieve a focused spot size of 150 nm.« less

A Penning discharge source for extreme ultraviolet calibration

NASA Technical Reports Server (NTRS)

Finley, David S.; Jelinsky, Patrick; Bowyer, Stuart; Malina, Roger F.

1986-01-01

A Penning discharge lamp for use in the calibration of instruments and components for the extreme ultraviolet has been developed. This source is sufficiently light and compact to make it suitable for mounting on the movable slit assembly of a grazing incidence Rowland circle monochromator. Because this is a continuous discharge source, it is suitable for use with photon counting detectors. Line radiation is provided both by the gas and by atoms sputtered off the interchangeable metal cathodes. Usable lines are produced by species as highly ionized as Ne IV and Al V. The wavelength coverage provided is such that a good density of emission lines is available down to wavelengths as short as 100A. This source fills the gap between 100 and 300A, which is inadequately covered by the other available compact continuous radiation sources.

UV Detection and Characterization of Plume Activity

NASA Astrophysics Data System (ADS)

Hansen, C. J.; Esposito, L. W.; Hendrix, A. R.

2017-12-01

Observations at ultraviolet wavelengths offer multiple techniques for detecting and characterizing plumes of gas erupting from planetary bodies. At Enceladus and Europa, UV observations include emission and absorption by water vapor molecules, and reflectance from ice particles. Emission: Emission features from electrons' interaction with water products H, OH, O and O2 can signal the presence of a plume. OH and O form a torus in the Saturn system, supplied by Enceladus' water vapor plume, that was detected before Cassini arrived in orbit [1, 2]. The nature of the ratio of H, O, and O2 emissions from Europa allow separation of the possible presence of plume(s) from Europa's O2 exosphere [3]. Absorption: The spectrum of starlight transmitted through an absorbing gas will have attenuation at UV wavelengths that are diagnostic of the composition of the gas. At Enceladus stellar and solar occultations by Enceladus' plume showed the primary composition to be water, constrained plume dimensions and revealed the presence of imbedded supersonic jets [4]. The amount of water coming from Enceladus and its variability over a decade has been measured [5]. Using Saturn as a source was not useful for Enceladus when it was observed in transit across Saturn. In contrast the putative detection of plume(s) at Europa has been bolstered by evidence that reflected light from Jupiter was being absorbed at particular places along Europa's limb as it transited Jupiter [6]. This contrast may reveal fundamental differences in the plumes at Europa and Enceladus [7]. Reflectance: With extremely long integration times the Enceladus plume has been observed reflecting light - light which is in turn absorbed by a small percentage of C2H4 gas being expelled [8]. The ice grain / gas ratio has been estimated by comparison of reflected light at near-IR wavelengths to the gas absorption of sunlight in the UV [9]. [1] Shemansky, D. E. et al. (1993) Nature 363:329; [2] Esposito, L. W. et al. (2005) Science 307:1251; [3] Roth, L. et al. (2013) Science 10.1126/1247051; [4] Hansen, C. J. et al. (2011) GRL 38:L11202; [5] Hansen, C. J. (2017) GRL 44:1; [6] Sparks, W. et al. (2016) Ast J 829:121; [7] Esposito, L. W. et al. (2017) IPPW abstract; [8] Shemansky, D. et al. (2016) AOGS abstract PS06-D5-PM2-P-022. [9] Hedman, M. et al. (2017), submitted.

Cylindrical angular spectrum using Fourier coefficients of point light source and its application to fast hologram calculation.

PubMed

Oh, Seungtaik; Jeong, Il Kwon

2015-11-16

We will introduce a new simple analytic formula of the Fourier coefficient of the 3D field distribution of a point light source to generate a cylindrical angular spectrum which captures the object wave in 360° in the 3D Fourier space. Conceptually, the cylindrical angular spectrum can be understood as a cylindrical version of the omnidirectional spectral approach of Sando et al. Our Fourier coefficient formula is based on an intuitive observation that a point light radiates uniformly in all directions. Our formula is defined over all frequency vectors lying on the entire sphere in the 3D Fourier space and is more natural and computationally more efficient for all around recording of the object wave than that of the previous omnidirectional spectral method. A generalized frequency-based occlusion culling method for an arbitrary complex object is also proposed to enhance the 3D quality of a hologram. As a practical application of the cylindrical angular spectrum, an interactive hologram example is presented together with implementation details.

EPICS controlled sample mounting robots at the GM/CA CAT.

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

Makarov, O. A.; Benn, R.; Corcoran, S.

2007-11-11

GM/CA CAT at Sector 23 of the advanced photon source (APS) is an NIH funded facility for crystallographic structure determination of biological macromolecules by X-ray diffraction [R.F. Fischetti, et al., GM/CA canted undulator beamlines for protein crystallography, Acta Crystallogr. A 61 (2005) C139]. The facility consists of three beamlines; two based on canted undulators and one on a bending magnet. The scientific and technical goals of the CAT emphasize streamlined, efficient throughput for a variety of sample types, sizes and qualities, representing the cutting edge of structural biology research. For this purpose all three beamlines are equipped with the ALS-stylemore » robots [C.W.Cork, et al. Status of the BCSB automated sample mounting and alignment system for macromolecular crystallography at the Advanced Light Source, SRI-2003, San-Francisco, CA, USA, August 25-29, 2003] for an automated mounting of cryo-protected macromolecular crystals. This report summarizes software and technical solutions implemented with the first of the three operational robots at beamline 23-ID-B. The automounter's Dewar can hold up to 72 or 96 samples residing in six Rigaku ACTOR magazines or ALS-style pucks, respectively. Mounting of a crystal takes approximately 2 s, during which time the temperature of the crystal is maintained near that of liquid nitrogen.« less

High-power AlGaN-based near-ultraviolet light-emitting diodes grown on Si(111)

NASA Astrophysics Data System (ADS)

Li, Zengcheng; Liu, Legong; Huang, Yingnan; Sun, Qian; Feng, Meixin; Zhou, Yu; Zhao, Hanmin; Yang, Hui

2017-07-01

High-power AlGaN-based 385 nm near-ultraviolet light-emitting diodes (UVA-LEDs) grown on Si(111) substrates are reported. The threading dislocation (TD) density of AlGaN was reduced by employing an Al-composition step-graded AlN/AlGaN multilayer buffer. V-shaped pits were intentionally incorporated into the active region to screen the carriers from the nonradiative recombination centers (NRCs) around the TDs and to facilitate hole injection. The light extraction efficiency was enhanced by the surface roughening of a thin-film (TF) vertical chip structure. The as-fabricated TF-UVA-LED exhibited a light output power of 960 mW at 500 mA, corresponding to an external quantum efficiency of 59.7%.

Indirect synthesis of Al{sub 2}O{sub 3}via radiation- or photochemical formation of its hydrated precursors

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

Barta, Jan, E-mail: jan.barta@fjfi.cvut.cz; Pospisil, Milan; Cuba, Vaclav

Graphical abstract: - Highlights: • Al{sub 2}O{sub 3} precursors were produced by UV/e-beam irradiation of aqueous solutions. • Depending on the aluminium salt (Cl{sup −} or NO{sub 3}{sup −}), either γ-AlOOH or Al(OH){sub 3} is formed. • The mechanism involved strongly depends on the presence of formate anion. • Prepared mesoporous solid phase has high specific surface area (<190 m{sup 2} g{sup −1}). • Calcination of the precursor leads to the formation of γ-/η-, θ- and α-Al{sub 2}O{sub 3}. - Abstract: γ-, θ- and α-modifications of aluminium oxide (alumina) were successfully prepared by calcination of precursor solid phase obtained bymore » irradiation of clear aqueous solutions by UV light or electron beam. For the precipitate to form, formate anion must be present in the solution in sufficient concentration. According to X-ray diffraction, the precipitate was found to consist of γ-AlOOH or a mixture of γ- and α-Al(OH){sub 3}, when aluminium chloride or aluminium nitrate was used, respectively. The addition of hydrogen peroxide as a ·OH radical source and sensitizer markedly improved the efficiency of the preparation. Some hints for the apparently very complex mechanism involved were listed and discussed. Calcination of the dried precipitate at 500–800 °C produced highly porous γ-alumina with high specific surface area (ca. 150 m{sup 2} g{sup −1}). Mixture of γ- and θ-transition aluminas was obtained at 1000 °C and pure, stable corundum α-Al{sub 2}O{sub 3} formed at 1200 °C. Samples were further investigated by means of scanning electron microscopy and specific surface area or porosity measurement. According to N{sub 2} adsorption isotherm, the precipitate contains mostly mesopores with average pore size 7 nm with specific surface area of ca. 100 m{sup 2} g{sup −1}. Possible applications of the material as sorbent or catalyst as well as a pure matrix for thermoluminescence dosimetry were briefly contemplated. Strong light-induced thermoluminescence was observed in both γ- and α-Al{sub 2}O{sub 3} samples at 300–400 °C, whereas in the absence of light, only an inexpressive glow peak at 179 °C was observed.« less

Seasonal Changes in Estuarine Dissolved Organic Matter Due to Variations in Discharge, Flushing Times and Wind-driven Mixing Events

NASA Astrophysics Data System (ADS)

Dixon, Jennifer Louise

Estuaries are highly productive habitats that transport and transform organic matter (OM), experience large changes in ionic composition and act as a transition zone between terrestrial and marine environments (Paerl et al. 1998; Markager et al. 2011; Osburn et al. 2012). OM source and matrix effects (such as salinity and pH) influence the chemical structure of DOM in estuaries and therefore affect its bioavailability, photo-reactivity, and its overall fate in these systems (Jaffe et al. 2004; Boyd et al. 2010; Pace et al. 2012; Osburn et al. 2012; Cawley et al. 2013). Within estuaries, dissolved organic matter (DOM) is a heterogeneous mixture of aromatic and aliphatic compounds, and its composition in aquatic systems varies spatially and temporally with source (Bauer and Bianchi 2011). However, the main source of DOM in estuaries, rivers and other aquatic systems, originates from vascular plant detritus, soil humus, older fossil (i.e., petrogenic) organic carbon, black carbon, marine OM and in situ production (Hedges 2002; Houghton 2007; Bauer and Bianchi 2011). Chromophoric dissolved organic matter (CDOM), the light absorbing fraction of DOM, can be characterized using optical methods such as absorption and fluorescence spectroscopy (e.g. Coble, 1996; Stedmon and Markager, 2003). By analyzing the spatial and temporal variability of DOM and CDOM within estuaries, information pertaining to OM source and fate across the freshwater-marine continuum can be obtained. These methods offer an inexpensive, non-destructive means for obtaining sensitive measurements of a diverse group of organic compounds. By using this technology to analyze the spatial and temporal variability of CDOM within estuaries, information pertaining to OM source and fate across the freshwater-marine continuum can be obtained (Fellman et al. 2011; Osburn et al. 2012; Murphy et al. 2014). Chemical biomarkers are also routinely used to identify DOM sources in coastal waters. Examples are carbon stable isotopes (Bauer, 2002) and lignin (e.g., Benner and Opsahl, 2001; Harvey and Mannino, 2001). Marine DOM derived from phytoplankton typically has carbon stable isotope (delta13C) values that range from --20 to --22‰, while terrestrial DOM derived from C3 land plants typically have delta13C values that range from --26 to --28‰ (Bauer, 2002). Lignin is an important component of vascular plants, thus making it a unique geochemical biomarker, which can be used to trace the fate of terrestrial DOM in coastal seawater (e.g., Hernes and Benner, 2003; Walker et al. 2009; Osburn and Stedmon, 2011). Further, the ratios of the different phenolic compounds derived from the oxidation of lignin can be used to distinguish between plant sources (e.g. angiosperm vs. gymnosperm, or woody vs. non-woody tissue) and the extent of exposure to degradation (Hedges et al. 1988). The highly productive, eutrophic waters of the Neuse River Estuary (NRE), in eastern North Carolina, USA, serve as a transition zone for terrigenous DOM between the head of the Neuse River and Pamlico Sound. Previous studies have determined that the NRE is dominated by inputs from riverine discharge, yet very clear shifts in DOM quality are apparent as discharge varied (Paerl et al. 1998; Osburn et al. 2012). Furthermore, flushing times within the NRE will aid in determining whether DOM is primarily autochthonous or allochthonous and if it is processed internally or transported downstream to the Pamlico Sound (Paerl et al. 1998; Mari et al. 2007, Peierls et al. 2012). Therefore, the main sources of DOM and its composition can change throughout an estuary depending on the hydrodynamic conditions. For example, increases in flushing time may allow for the accumulation of autochthonous DOM because of (1) planktonic communities within the water column having more time to utilize nutrients within the system, resulting in phytoplankton blooms and (2) lower inputs of allochthonous OM from the NRE's watershed (Dixon et al. accepted). Therefore, the main sources of DOM and its composition can change throughout an estuary depending on the hydrodynamic conditions.

EPICS SCA CLIENTS ON THE .NET X64 PLATFORM

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

Timossi, Chris; Nishimura, Hiroshi

2006-10-19

We have developed a .NET assembly, which we call SCA.NET,which we have been using for building EPICS based control roomapplications at the Advanced Light Source (ALS). In this paper we reporton our experiences building a 64-bit version of SCA.NET and theunderlying channel access libraries for Windows XP x64 (using a dual coreAMD Athlon CPU). We also report on our progress in building newaccelerator control applications for this environment.

Development of GaN-based micro chemical sensor nodes

NASA Technical Reports Server (NTRS)

Son, Kyung-ah; Prokopuk, Nicholas; George, Thomas; Moon, Jeong S.

2005-01-01

Sensors based on III-N technology are gaining significant interest due to their potential for monolithic integration of RF transceivers and light sources and the capability of high temperature operations. We are developing a GaN-based micro chemical sensor node for remote detection of chemical toxins, and present electrical responses of AlGaN/GaN HEMT (High Electron Mobility Transistor) sensors to chemical toxins as well as other common gases.

Glass-Based Transparent Conductive Electrode: Its Application to Visible-to-Ultraviolet Light-Emitting Diodes.

PubMed

Lee, Tae Ho; Kim, Kyeong Heon; Lee, Byeong Ryong; Park, Ju Hyun; Schubert, E Fred; Kim, Tae Geun

2016-12-28

Nitride-based ultraviolet light-emitting diodes (UV LEDs) are promising replacements for conventional UV lamps. However, the external quantum efficiency of UV LEDs is much lower than for visible LEDs due to light absorption in the p-GaN contact and electrode layers, along with p-AlGaN growth and doping issues. To minimize such absorption, we should obtain direct ohmic contact to p-AlGaN using UV-transparent ohmic electrodes and not use p-GaN as a contact layer. Here, we propose a glass-based transparent conductive electrode (TCE) produced using electrical breakdown (EBD) of an AlN thin film, and we apply the thin film to four (Al)GaN-based visible and UV LEDs with thin buffer layers for current spreading and damage protection. Compared to LEDs with optimal ITO contacts, our LEDs with AlN TCEs exhibit a lower forward voltage, higher light output power, and brighter light emission for all samples. The ohmic transport mechanism for current injection and spreading from the metal electrode to p-(Al)GaN layer via AlN TCE is also investigated by analyzing the p-(Al)GaN surface before and after EBD.

The Design and Use of Planetary Science Video Games to Teach Content while Enhancing Spatial Reasoning Skills

NASA Astrophysics Data System (ADS)

Ziffer, Julie; Nadirli, Orkhan; Rudnick, Benjamin; Pinkham, Sunny; Montgomery, Benjamin

2016-10-01

Traditional teaching of Planetary Science requires students to possess well developed spatial reasoning skills (SRS). Recent research has demonstrated that SRS, long known to be crucial to math and science success, can be improved among students who lack these skills (Sorby et al., 2009). Teaching spatial reasoning is particularly valuable to women and minorities who, through societal pressure, often doubt their abilities (Hill et al., 2010). To address SRS deficiencies, our team is developing video games that embed SRS training into Planetary Science content. Our first game, on Moon Phases, addresses the two primary challenges faced by students trying to understand the Sun-Earth-Moon system: 1) visualizing the system (specifically the difference between the Sun-Earth orbital plane and the Earth-Moon orbital plane) and 2) comprehending the relationship between time and the position-phase of the Moon. In our second video game, the student varies an asteroid's rotational speed, shape, and orientation to the light source while observing how these changes effect the resulting light curve. To correctly pair objects to their light curves, students use spatial reasoning skills to imagine how light scattering off a three dimensional rotating object is imaged on a sensor plane and is then reduced to a series of points on a light curve plot. These two games represent the first of our developing suite of high-interest video games designed to teach content while increasing the student's competence in spatial reasoning.

InGaN directional coupler made with a one-step etching technique

NASA Astrophysics Data System (ADS)

Gao, Xumin; Yuan, Jialei; Yang, Yongchao; Zhang, Shuai; Shi, Zheng; Li, Xin; Wang, Yongjin

2017-06-01

We propose, fabricate and characterize an on-chip integration of light source, InGaN waveguide, directional coupler and photodiode, in which AlGaN layers are used as top and bottom optical claddings to form an InGaN waveguide for guiding the in-plane emitted light from the InGaN/GaN multiple-quantum-well light-emitting diode (MQW-LED). The difference in etch rate caused by different exposure windows leads to an etching depth discrepancy using the one-step etching technique, which forms the InGaN directional coupler with the overlapped underlying slab. Light propagation results directly confirm effective light coupling in the InGaN directional coupler, which is achieved through high-order guided modes. The InGaN waveguide couples the modulated light from the InGaN/GaN MQW-LED and transfers part of light to the coupled waveguide via the InGaN directional coupler. The in-plane InGaN/GaN MQW-photodiode absorbs the guided light by the coupled InGaN waveguide and induces the photocurrent. The on-chip InGaN photonic integration experimentally demonstrates an in-plane light communication with a data transmission of 50 Mbps.

Origin of low δ26Mg basalts with EM-I component: Evidence for interaction between enriched lithosphere and carbonated asthenosphere

NASA Astrophysics Data System (ADS)

Tian, H.; Yang, W.; Li, S. G.; Ke, S.; Chu, Z. Y.

2016-12-01

Many studies have focused on the interactions between recycled materials and depleted mantle to explain the origins of EM and HIMU components (e.g., Cohen and O'Nions, 1982; White and Hofmann, 1982). However, little is known about the interactions between recycled materials and enriched mantle and the associated consequences, e.g., late recycled crustal material overprints mantle previously enriched by earlier recycling events of the crust. Recently, light Mg isotopic composition of the basalts from North China Craton (NCC) and South China Block (SCB) has been attributed to recycled carbonate metasomatism from subducted Pacific slab (Yang et al., 2012; Huang et al., 2015). If this explanation is correct, the Cenozoic basalts from Northeast (NE) China should also contain light Mg isotopic compositions. The basalts from NE China have EMI Sr-Nd-Pb isotopic features that are distinct from the NCC and SCB basalts, indicating the contribution of an enriched mantle source (Choi et al., 2006; Chu et al., 2013). Therefore, Mg isotopic compositions of the Cenozoic basalts from NE China will help to determine the interaction between recycled sedimentary carbonates and an enriched mantle. Consistent with the hypothesis, our results show that the Cenozoic basalts from Wudalianchi and Erkeshan, NE China, have homogeneous and light Mg isotopic compositions (δ26Mg =-0.57 to -0.46‰). Based on the similarity to the basalts from NCC and SCB, their light Mg isotopic feature should also be derived from carbonate metasomatism (i.e. carbonated asthenosphere). In addition to that, a question arise that why the interaction between carbonated asthenosphere and the EM-I SLCM significantly modify the trace element and Sr-Nd-Pb isotopic composition of the mantle-derived melt, but have little effect on the Mg isotopes? The possible mechanism is the interaction between low SiO2 melt and peridotite, which converts pyroxene to olivine, as reported in previous studies (e.g., Kelemen et al., 1992; Edwards and Malpas, 1996; Zhou et al., 1996, 2014). During the interaction, the trace elements of the EM-I SCLM largely entered the melt, and all Mg was transferred from Opx and Cpx into the newly formed olivine. Consequently, the Wudalianchi and Erkeshan basalts preserve low δ26Mg and obtain EM-I Sr-Nd-Pb isotopic compositions (Fig. 1).

14 CFR 151.13 - Federal-aid Airport Program: Policy affecting landing aid requirements.

Code of Federal Regulations, 2012 CFR

2012-01-01

... (ALS). (2) In-runway lighting. (3) High intensity runway lighting. (4) Runway distance markers. For the purposes of this section “approach lighting system (ALS)” is a standard configuration of aeronautical... ALS and ILS, has been programmed by the FAA with funds then available therefor; (b) An extension of 3...

14 CFR 151.13 - Federal-aid Airport Program: Policy affecting landing aid requirements.

Code of Federal Regulations, 2011 CFR

2011-01-01

... (ALS). (2) In-runway lighting. (3) High intensity runway lighting. (4) Runway distance markers. For the purposes of this section “approach lighting system (ALS)” is a standard configuration of aeronautical... ALS and ILS, has been programmed by the FAA with funds then available therefor; (b) An extension of 3...

14 CFR 151.13 - Federal-aid Airport Program: Policy affecting landing aid requirements.

Code of Federal Regulations, 2013 CFR

2013-01-01

... (ALS). (2) In-runway lighting. (3) High intensity runway lighting. (4) Runway distance markers. For the purposes of this section “approach lighting system (ALS)” is a standard configuration of aeronautical... ALS and ILS, has been programmed by the FAA with funds then available therefor; (b) An extension of 3...

14 CFR 151.13 - Federal-aid Airport Program: Policy affecting landing aid requirements.

Code of Federal Regulations, 2014 CFR

2014-01-01

... (ALS). (2) In-runway lighting. (3) High intensity runway lighting. (4) Runway distance markers. For the purposes of this section “approach lighting system (ALS)” is a standard configuration of aeronautical... ALS and ILS, has been programmed by the FAA with funds then available therefor; (b) An extension of 3...

14 CFR 151.13 - Federal-aid Airport Program: Policy affecting landing aid requirements.

Code of Federal Regulations, 2010 CFR

2010-01-01

... (ALS). (2) In-runway lighting. (3) High intensity runway lighting. (4) Runway distance markers. For the purposes of this section “approach lighting system (ALS)” is a standard configuration of aeronautical... ALS and ILS, has been programmed by the FAA with funds then available therefor; (b) An extension of 3...

Atom chip gravimeter

NASA Astrophysics Data System (ADS)

Schubert, Christian; Abend, Sven; Gebbe, Martina; Gersemann, Matthias; Ahlers, Holger; Müntinga, Hauke; Matthias, Jonas; Sahelgozin, Maral; Herr, Waldemar; Lämmerzahl, Claus; Ertmer, Wolfgang; Rasel, Ernst

2016-04-01

Atom interferometry has developed into a tool for measuring rotations [1], accelerations [2], and testing fundamental physics [3]. Gravimeters based on laser cooled atoms demonstrated residual uncertainties of few microgal [2,4] and were simplified for field applications [5]. Atomic gravimeters rely on the interference of matter waves which are coherently manipulated by laser light fields. The latter can be interpreted as rulers to which the position of the atoms is compared. At three points in time separated by a free evolution, the light fields are pulsed onto the atoms. First, a coherent superposition of two momentum states is produced, then the momentum is inverted, and finally the two trajectories are recombined. Depending on the acceleration the atoms experienced, the number of atoms detected in the output ports will change. Consequently, the acceleration can be determined from the output signal. The laser cooled atoms with microkelvin temperatures used in state-of-the-art gravimeters impose limits on the accuracy [4]. Therefore, ultra-cold atoms generated by Bose-Einstein condensation and delta-kick collimation [6,7] are expected to be the key for further improvements. These sources suffered from a low flux implying an incompatible noise floor, but a competitive performance was demonstrated recently with atom chips [8]. In the compact and robust setup constructed for operation in the drop tower [6] we demonstrated all steps necessary for an atom chip gravimeter with Bose-Einstein condensates in a ground based operation. We will discuss the principle of operation, the current performance, and the perspectives to supersede the state of the art. The authors thank the QUANTUS cooperation for contributions to the drop tower project in the earlier stages. This work is supported by the German Space Agency (DLR) with funds provided by the Federal Ministry for Economic Affairs and Energy (BMWi) due to an enactment of the German Bundestag under grant numbers DLR 50WM1552-1557 (QUANTUS-IV-Fallturm) and by the Deutsche Forschungsgemeinschaft in the framework of the SFB 1128 geo-Q. [1] P. Berg et al., Composite-Light-Pulse Technique for High-Precision Atom Interferometry, Phys. Rev. Lett., 114, 063002, 2015. [2] A. Peters et al., Measurement of gravitational acceleration by dropping atoms, Nature 400, 849, 1999. [3] D. Schlippert et al., Quantum Test of the Universality of Free Fall, Phys. Rev. Lett., 112, 203002, 2014. [4] A. Louchet-Chauvet et al., The influence of transverse motion within an atomic gravimeter, New J. Phys. 13, 065026, 2011. [5] Q. Bodart et al., A cold atom pyramidal gravimeter with a single laser beam, Appl. Phys. Lett. 96, 134101, 2010. [6] H. Müntinga et al., Interferometry with Bose-Einstein Condensates in Microgravity, Phys. Rev. Lett., 110, 093602, 2013. [7] T. Kovachy et al., Matter Wave Lensing to Picokelvin Temperatures, Phys. Rev. Lett. 114, 143004, 2015. [8] J. Rudolph et al., A high-flux BEC source for mobile atom interferometers, New J. Phys. 17, 065001, 2015.

Memory colours and colour quality evaluation of conventional and solid-state lamps.

PubMed

Smet, Kevin A G; Ryckaert, Wouter R; Pointer, Michael R; Deconinck, Geert; Hanselaer, Peter

2010-12-06

A colour quality metric based on memory colours is presented. The basic idea is simple. The colour quality of a test source is evaluated as the degree of similarity between the colour appearance of a set of familiar objects and their memory colours. The closer the match, the better the colour quality. This similarity was quantified using a set of similarity distributions obtained by Smet et al. in a previous study. The metric was validated by calculating the Pearson and Spearman correlation coefficients between the metric predictions and the visual appreciation results obtained in a validation experiment conducted by the authors as well those obtained in two independent studies. The metric was found to correlate well with the visual appreciation of the lighting quality of the sources used in the three experiments. Its performance was also compared with that of the CIE colour rendering index and the NIST colour quality scale. For all three experiments, the metric was found to be significantly better at predicting the correct visual rank order of the light sources (p < 0.1).

EUV multilayer coatings for the Atmospheric Imaging Assembly instrument aboard the Solar Dynamics Observatory

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

Soufli, R; Windt, D L; Robinson, J C

2006-02-09

Multilayer coatings for the 7 EUV channels of the AIA have been developed and completed successfully on all AIA flight mirrors. Mo/Si coatings (131, 171, 193.5, 211 {angstrom}) were deposited at Lawrence Livermore National Laboratory (LLNL). Mg/SiC (304, 335 {angstrom}) and Mo/Y (94 {angstrom}) coatings were deposited at Columbia University. EUV reflectance of the 131/335 {angstrom}, 171 {angstrom}, 193.5/211 {angstrom} primary and secondary flight mirrors and the 94/304 {angstrom} secondary flight mirror was measured at beamline 6.3.2. of the Advanced Light Source (ALS) at LBNL. EUV reflectance of the 94/304 {angstrom} primary and secondary flight mirrors was measured at beamlinemore » X24C of the National Synchrotron Light Source (NSLS) at Brookhaven National Lab. Preliminary EUV reflectance measurements of the 94, 304 and 335 {angstrom} coatings were performed with a laser plasma source reflectometer located at Columbia University. Prior to multilayer coating, Atomic Force Microscopy (AFM) characterization and cleaning of all flight substrates was performed at LLNL.« less

Cassiopeia A supernova

NASA Image and Video Library

2017-12-08

NASA's Fermi Closes on Source of Cosmic Rays New images from NASA's Fermi Gamma-ray Space Telescope show where supernova remnants emit radiation a billion times more energetic than visible light. The images bring astronomers a step closer to understanding the source of some of the universe's most energetic particles -- cosmic rays. This composite shows the Cassiopeia A supernova remnant across the spectrum: Gamma rays (magenta) from NASA's Fermi Gamma-ray Space Telescope; X-rays (blue, green) from NASA's Chandra X-ray Observatory; visible light (yellow) from the Hubble Space Telescope; infrared (red) from NASA's Spitzer Space Telescope; and radio (orange) from the Very Large Array near Socorro, N.M. Credit: NASA/DOE/Fermi LAT Collaboration, CXC/SAO/JPL-Caltech/Steward/O. Krause et al., and NRAO/AUI For more information: www.nasa.gov/mission_pages/GLAST/news/cosmic-rays-source.... NASA Goddard Space Flight Center is home to the nation's largest organization of combined scientists, engineers and technologists that build spacecraft, instruments and new technology to study the Earth, the sun, our solar system, and the universe. Follow us on Twitter Join us on Facebook

75 FR 61786 - Northern Lights Fund Trust, et al.; Notice of Application

Federal Register 2010, 2011, 2012, 2013, 2014

2010-10-06

...] Northern Lights Fund Trust, et al.; Notice of Application September 30, 2010. AGENCY: Securities and... certain financial instruments. Applicants: Northern Lights Fund Trust (``NLFT''), Arrow Investment Advisors, LLC (``AIA''), and Northern Lights Distributors, LLC (``NLD''). Filing Dates: The application was...

Electrowetting retroreflectors: Scalable and wide-spectrum modulation between corner cube and scattering reflection

NASA Astrophysics Data System (ADS)

Kilaru, M. K.; Cumby, B.; Heikenfeld, J.

2009-01-01

Corner cube and spherical retroreflectors are ubiquitous in conspicuity and range-finding applications since they reflect light back to the illumination source with unmatched efficiency. We report here a switchable electrowetting retroreflector platform that provides multiple novel features, including (a) using <0.5 μJ/cm2 electrical energy to switch from a light scattering state, (b) low loss and wide spectrum as limited only by the absorption spectrum of water, (c) use of ultrasimple self-assembly of 103-105 liquid lenslets/in.2 on a polymer/Al corner-cube substrate, and (d) change in retroreflected irradiance of >10:1 over a ±30° field of view.

Effect of quantum-well thickness on the optical polarization of AlGaN-based ultraviolet light-emitting diodes

NASA Astrophysics Data System (ADS)

Liu, Cheng; Zhang, Jing

2018-02-01

Optical polarization from AlGaN quantum well (QW) is crucial for realizing high-efficiency deep-ultraviolet (UV) light-emitting diodes (LEDs) because it determines the light emission patterns and light extraction mechanism of the devices. As the Al-content of AlGaN QW increases, the valence bands order changes and consequently the light polarization switches from transverse-electric (TE) to transverse-magnetic (TM) owing to the different sign and the value of the crystal field splitting energy between AlN (-169meV) and GaN (10meV). Several groups have reported that the ordering of the bands and the TE/TM crossover Al-content could be influenced by the strain state and the quantum confinement from the AlGaN QW system. In this work, we investigate the influence of QW thickness on the optical polarization switching point from AlGaN QW with AlN barriers by using 6-band k•p model. The result presents a decreasing trend of the critical Al-content where the topmost valence band switches from heave hole (HH) to crystal field spilt-off (CH) with increasing QW thicknesses due to the internal electric field and the strain state from the AlGaN QW. Instead, the TE- and TM-polarized spontaneous emission rates switching Al-content rises first and falls later because of joint consequence of the band mixing effect and the Quantum Confined Stark Effect. The reported optical polarization from AlGaN QW emitters in the UV spectral range is assessed in this work and the tendency of the polarization switching point shows great consistency with the theoretical results, which deepens the understanding of the physics from AlGaN QW UV LEDs.

Sub-microradian Surface Slope Metrology with the ALS Developmental Long Trace Profiler

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

Yashchuk, Valeriy V.; Barber, Samuel; Domning, Edward E.

2009-06-15

Development of X-ray optics for 3rd and 4th generation X-ray light sources with a level of surface slope precision of 0.1-0.2 {micro}rad requires the development of adequate fabrication technologies and dedicated metrology instrumentation and methods. Currently, the best performance of surface slope measurement has been achieved with the NOM (Nanometer Optical Component Measuring Machine) slope profiler at BESSY (Germany) [1] and the ESAD (Extended Shear Angle Difference) profiler at the PTB (Germany) [2]. Both instruments are based on electronic autocollimators (AC) precisely calibrated for the specific application [3] with small apertures of 2.5-5 mm in diameter. In the present work,more » we describe the design, initial alignment and calibration procedures, the instrumental control and data acquisition system, as well as the measurement performance of the Developmental Long Trace Profiler (DLTP) slope measuring instrument recently brought into operation at the Advanced Light Source (ALS) Optical Metrology Laboratory (OML). Similar to the NOM and ESAD, the DLTP is based on a precisely calibrated autocollimator. However, this is a reasonably low budget instrument used at the ALS OML for the development and testing of new measuring techniques and methods. Some of the developed methods have been implemented into the ALS LTP-II (slope measuring long trace profiler [4]) which was recently upgraded and has demonstrated a capability for 0.25 {micro}rad surface metrology [5]. Performance of the DLTP was verified via a number of measurements with high quality reference mirrors. A comparison with the corresponding results obtained with the world's best slope measuring instrument, the BESSY NOM, proves the accuracy of the DLTP measurements on the level of 0.1-0.2 {micro}rad depending on the curvature of a surface under test. The directions of future work to develop a surface slope measuring profiler with nano-radian performance are also discussed.« less

Fast spatial atomic layer deposition of Al{sub 2}O{sub 3} at low temperature (<100 °C) as a gas permeation barrier for flexible organic light-emitting diode displays

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

Choi, Hagyoung; Shin, Seokyoon; Jeon, Hyeongtag, E-mail: hjeon@hanyang.ac.kr

2016-01-15

The authors developed a high throughput (70 Å/min) and scalable space-divided atomic layer deposition (ALD) system for thin film encapsulation (TFE) of flexible organic light-emitting diode (OLED) displays at low temperatures (<100 °C). In this paper, the authors report the excellent moisture barrier properties of Al{sub 2}O{sub 3} films deposited on 2G glass substrates of an industrially relevant size (370 × 470 mm{sup 2}) using the newly developed ALD system. This new ALD system reduced the ALD cycle time to less than 1 s. A growth rate of 0.9 Å/cycle was achieved using trimethylaluminum as an Al source and O{sub 3} as an O reactant. Themore » morphological features and step coverage of the Al{sub 2}O{sub 3} films were investigated using field emission scanning electron microscopy. The chemical composition was analyzed using Auger electron spectroscopy. These deposited Al{sub 2}O{sub 3} films demonstrated a good optical transmittance higher than 95% in the visible region based on the ultraviolet visible spectrometer measurements. Water vapor transmission rate lower than the detection limit of the MOCON test (less than 3.0 × 10{sup −3} g/m{sup 2} day) were obtained for the flexible substrates. Based on these results, Al{sub 2}O{sub 3} deposited using our new high-throughput and scalable spatial ALD is considered a good candidate for preparation of TFE films of flexible OLEDs.« less

Optical and scintillation properties of ce-doped (Gd2Y1)Ga2.7Al2.3O12 single crystal grown by Czochralski method

NASA Astrophysics Data System (ADS)

Wang, Chao; Wu, Yuntao; Ding, Dongzhou; Li, Huanying; Chen, Xiaofeng; Shi, Jian; Ren, Guohao

2016-06-01

Multicomponent garnets, due to their excellent light yield and energy resolution, become one of the most promising scintillators used for homeland security and nuclear non-proliferation applications. This work focuses on the optimization of Ce-doped (Gd,Y)3(Ga,Al)5O12 scintillators using a combination strategy of pre-screening and scale-up. Ce-doped GdxY1-xGayAl5-yO12 (x=1, 2 and y=2, 2.2, 2.5, 2.7, 3) polycrystalline powders were prepared by high-temperature solid state reaction method. The desired garnet phase in all the samples was confirmed using X-ray diffraction measurement. By comparing the radioluminescence intensity, the highest scintillation efficiency was achieved at a component of Gd2Y1Ga2.7Al2.3O12:Ce powders. A (Gd2Y1)Ga2.7Al2.3O12 doped with 1% Ce single crystal with dimensions of Ø35×40 mm was grown by Czochralski method using a <111> oriented seed. Luminescence and scintillation properties were measured. An optical transmittance of 84% was achieved in the concerned wavelength from 500 to 800 nm. Its 5d-4f emission of Ce3+ is at 530 nm. The light yield of a Ce1%: Gd2Y1Ga2.7Al2.3O12 single crystal slab at a size of 5×5×1 mm3 can reach about 65,000±3000 Ph/MeV along with two decay components of 94 and 615 ns under 137Cs source irradiation.

282-nm AlGaN-based deep ultraviolet light-emitting diodes with improved performance on nano-patterned sapphire substrates

NASA Astrophysics Data System (ADS)

Dong, Peng; Yan, Jianchang; Wang, Junxi; Zhang, Yun; Geng, Chong; Wei, Tongbo; Cong, Peipei; Zhang, Yiyun; Zeng, Jianping; Tian, Yingdong; Sun, Lili; Yan, Qingfeng; Li, Jinmin; Fan, Shunfei; Qin, Zhixin

2013-06-01

We first report AlGaN-based deep ultraviolet light-emitting diodes (UV-LEDs) grown on nano-patterned sapphire substrates (NPSS) prepared through a nanosphere lithography technique. The AlN coalescence thickness on NPSS is only 3 μm due to AlN's nano-scaled lateral growth, which also leads to low dislocation densities in AlN and epi-layers above. On NPSS, the light-output power of a 282-nm UV-LED reaches 3.03 mW at 20 mA with external quantum efficiency of 3.45%, exhibiting 98% better performance than that on flat sapphire. Temperature-dependent photoluminescence reveals this significant enhancement to be a combination of higher internal quantum efficiency and higher light extraction efficiency.

Thermo-plasmonics: playing with temperature at the nanoscale (Conference Presentation)

NASA Astrophysics Data System (ADS)

Alabastri, Alessandro; Malerba, Mario; Calandrini, Eugenio; Toma, Andrea; Proietti Zaccaria, Remo

2017-02-01

The electro-magnetic field generated within and around dissipative nano-structures upon light radiation is intimately associated to the formation of localized heat sources. In turn, this phenomenon determines localized temperature variations, effect which can be exploited for applications such as photocatalysis [1], nanochemistry [2] or sensor devices [3]. Here we show how the geometrical characteristics of plasmonic nano-structures can indeed be used to modulate the temperature response. The idea is that when metallic structures interact with an electromagnetic field they heat up due to Joule effect. The corresponding temperature variation modifies the optical response of the structure [4,5] and thus its heating process. The key finding is that, depending on the structures geometry, absorption efficiency can either increase or decrease with temperature. Since absorption relates to the thermal energy dissipation and thus to temperature increase, the mechanism leads to positive or negative loops. Consequently, not only an error would be made by neglecting the role of temperature, but it would be not even possible to know, a priori, if the error is towards higher or lower absorption values. Our model can be utilized to study opto-thermal phenomena when high temperature or high intensity sources are employed. [1] M. Honda et al., Appl. Phys. Lett. 104, 061108 (2014) [2] G. Baffou et al., Chem. Soc. Rev. 43, 3898 (2014) [3] S. Ozdemir et al., J. Lightwave Tech. 21, 805 (2003) [4] A. Alabastri et al., ACS Photonics 2, 115 (2015) [5] A. Alabastri et al., Materials 6, 4879 (2013)

High conductivity and transparent aluminum-based multi-layer source/drain electrodes for thin film transistors

NASA Astrophysics Data System (ADS)

Yao, Rihui; Zhang, Hongke; Fang, Zhiqiang; Ning, Honglong; Zheng, Zeke; Li, Xiaoqing; Zhang, Xiaochen; Cai, Wei; Lu, Xubing; Peng, Junbiao

2018-02-01

In this study, high conductivity and transparent multi-layer (AZO/Al/AZO-/Al/AZO) source/drain (S/D) electrodes for thin film transistors were fabricated via conventional physical vapor deposition approaches, without toxic elements or further thermal annealing process. The 68 nm-thick multi-layer films with excellent optical properties (transparency: 82.64%), good electrical properties (resistivity: 6.64  ×  10-5 Ω m, work function: 3.95 eV), and superior surface roughness (R q   =  0.757 nm with scanning area of 5  ×  5 µm2) were fabricated as the S/D electrodes. Significantly, comprehensive performances of AZO films are enhanced by the insertion of ultra-thin Al layers. The optimal transparent TFT with this multi-layer S/D electrodes exhibited a decent electrical performance with a saturation mobility (µ sat) of 3.2 cm2 V-1 s-1, an I on/I off ratio of 1.59  ×  106, a subthreshold swing of 1.05 V/decade. The contact resistance of AZO/Al/AZO/Al/AZO multi-layer electrodes is as low as 0.29 MΩ. Moreover, the average visible light transmittance of the unpatterned multi-layers constituting a whole transparent TFT could reach 72.5%. The high conductivity and transparent multi-layer S/D electrodes for transparent TFTs possessed great potential for the applications of the green and transparent displays industry.

Low-threshold voltage ultraviolet light-emitting diodes based on (Al,Ga)N metal-insulator-semiconductor structures

NASA Astrophysics Data System (ADS)

Liang, Yu-Han; Towe, Elias

2017-12-01

Al-rich III-nitride-based deep-ultraviolet (UV) (275-320 nm) light-emitting diodes are plagued with a low emission efficiency and high turn-on voltages. We report Al-rich (Al,Ga)N metal-insulator-semiconductor UV light-emitting Schottky diodes with low turn-on voltages of <3 V, which are about half those of typical (Al,Ga)N p-i-n diodes. Our devices use a thin AlN film as the insulator and an n-type Al0.58Ga0.42N film as the semiconductor. To improve the efficiency, we inserted a GaN quantum-well structure between the AlN insulator and the n-type Al x Ga1- x N semiconductor. The benefits of the quantum-well structure include the potential to tune the emission wavelength and the capability to confine carriers for more efficient radiative recombination.

Ultra-high Resolution Coherent X-ray Imaging of Nano-Materials

NASA Astrophysics Data System (ADS)

Shapiro, David

A revolution is underway in the field of x-ray microscopy driven by the develop of experimental, theoretical and computational means of producing a complete description of coherent imaging systems from x-ray diffraction data. The methods being developed not only allow for full quantification and removal of all optical aberrations but also extension of the numerical aperture to the diffraction limit. One such method under intensive development is x-ray ptychography. This is a scanned probe method that reconstructs a scattering object and its illumination from coherent diffraction data. Within the first few years of development at the Advanced Light Source (ALS), Lawrence Berkeley National Laboratory, this method has already achieved the highest resolution x-ray images ever recorded in two, three and four dimensions. With the ability of x-rays to penetrate significantly more matter than electrons, their short wavelength and their sensitivity to chemical and magnetic states of matter, x-ray ptychography is set to revolutionize how we see the nano-scale world. In this presentation I will briefly describe the technical framework for how various methods work and will give a detailed account of a practical implementation at the ALS along with various scientific applications. The Advanced Light Source is supported by the Director, Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.

Bendable Focusing X-Ray Optics for the ALS and the LCLS/FEL: Design, Metrology, and Performance

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

Yashchuk, V. V.; Yuan, S.; Baker, S.

2010-06-02

We review the recent development of bendable x-ray optics used for focusing of beams of soft and hard x-rays at the Advanced Light Source (ALS) at Lawrence Berkeley National Laboratory and at the Linac Coherent Light Source (LCLS) x-ray free electron laser (FEL) at the Stanford Linear Accelerator Center (SLAC) National Accelerator Laboratory. For simultaneous focusing in the tangential and sagittal directions, two elliptically cylindrical reflecting elements, a Kirkpatrick-Baez (KB) pair, are used. Because fabrication of elliptical surfaces is complicated, the cost of directly fabricated tangential elliptical cylinders is often prohibitive. Moreover, such optics cannot be easily readjusted for usemore » in multiple, different experimental arrangements, e.g. at different focal distances. This is in contrast to flat optics that are simpler to manufacture and easier to measure by conventional interferometry. The tangential figure of a flat substrate is changed by placing torques (couples) at each end. Depending on the applied couples, one can tune the shape close to a desired tangential cylinder, ellipse or parabola. We review the nature of the bending, requirements and approaches to the mechanical design, describe original optical and at-wavelength techniques for optimal tuning of bendable optics and alignment on the beamline, and provide beamline performance of the bendable optics used for sub-micro and nano focusing of soft x-rays.« less

Structure and energetic basis of overrepresented λ light chain in systemic light chain amyloidosis patients.

PubMed

Zhao, Jun; Zhang, Baohong; Zhu, Jianwei; Nussinov, Ruth; Ma, Buyong

2018-06-01

Amyloid formation and deposition of immunoglobulin light-chain proteins in systemic amyloidosis (AL) cause major organ failures. While the κ light-chain is dominant (λ/κ=1:2) in healthy individuals, λ is highly overrepresented (λ/κ=3:1) in AL patients. The structural basis of the amyloid formation and the sequence preference are unknown. We examined the correlation between sequence and structural stability of dimeric variable domains of immunoglobulin light chains using molecular dynamics simulations of 24 representative dimer interfaces, followed by energy evaluation of conformational ensembles for 20 AL patients' light chain sequences. We identified a stable interface with displaced N-terminal residues, provides the structural basis for AL protein fibrils formation. Proline isomerization may cause the N-terminus to adopt amyloid-prone conformations. We found that λ light-chains prefer misfolded dimer conformation, while κ chain structures are stabilized by a natively folded dimer. Our study may facilitate structure-based small molecule and antibody design to inhibit AL. This article is part of a Special Issue entitled: Accelerating Precision Medicine through Genetic and Genomic Big Data Analysis edited by Yudong Cai & Tao Huang. Copyright © 2017 Elsevier B.V. All rights reserved.

Are PSR 0656+14, PSR 0950+08, and PSR 1822-09 gamma ray pulsars?

NASA Technical Reports Server (NTRS)

Brown, Lawrence E.; Hartmann, Dieter H.

1993-01-01

The possible discovery of three new gamma-ray pulsars PSR 0656+14, PSR 0950+08, and PSR 1822-09 (Ma, Lu, Yu, and Young, 1993) in data obtained with the COS-B experiment is reinvestigated using a refined technique for pulsar light curve analysis. The results of this study do not confirm the previously claimed gamma-ray pulsar nature of any of these pulsars. Even when using the standard epoch folding technique in conjunction with energy-dependent acceptance cones, we do not detect pulsed gamma-ray emission from these sources. We suspect that insufficient position accuracy is the cause for the discrepancy between our results and those of Ma et al. (1993). We do not rule out that any one of the three candidates, or all of them, is in fact a gamma-ray pulsar, but their spin properties must differ from those derived by Ma et al. (1993). More work is needed to determine the correct high-energy properties of these three sources.

Light-extraction enhancement of GaN-based 395  nm flip-chip light-emitting diodes by an Al-doped ITO transparent conductive electrode.

PubMed

Xu, Jin; Zhang, Wei; Peng, Meng; Dai, Jiangnan; Chen, Changqing

2018-06-01

The distinct ultraviolet (UV) light absorption of indium tin oxide (ITO) limits the performance of GaN-based near-UV light-emitting diodes (LEDs). Herein, we report an Al-doped ITO with enhanced UV transmittance and low sheet resistance as the transparent conductive electrode for GaN-based 395 nm flip-chip near-UV LEDs. The thickness dependence of optical and electrical properties of Al-doped ITO films is investigated. The optimal Al-doped ITO film exhibited a transmittance of 93.2% at 395 nm and an average sheet resistance of 30.1  Ω/sq. Meanwhile, at an injection current of 300 mA, the forward voltage decreased from 3.14 to 3.11 V, and the light output power increased by 13% for the 395 nm near-UV flip-chip LEDs with the optimal Al-doped ITO over those with pure ITO. This Letter provides a simple and repeatable approach to further improve the light extraction efficiency of GaN-based near-UV LEDs.

The effect of light soaking on crystalline silicon surface passivation by atomic layer deposited Al2O3

NASA Astrophysics Data System (ADS)

Liao, Baochen; Stangl, Rolf; Mueller, Thomas; Lin, Fen; Bhatia, Charanjit S.; Hoex, Bram

2013-01-01

The effect of light soaking of crystalline silicon wafer lifetime samples surface passivated by thermal atomic layer deposited (ALD) Al2O3 is investigated in this paper. Contrary to other passivation materials used in solar cell applications (i.e., SiO2, SiNx), using thermal ALD Al2O3, an increase in effective carrier lifetime after light soaking under standard testing conditions is observed for both p-type (˜45%) and n-type (˜60%) FZ c-Si lifetime samples. After light soaking and storing the samples in a dark and dry environment, the effective lifetime decreases again and practically returns to the value before light soaking. The rate of lifetime decrease after light soaking is significantly slower than the rate of lifetime increase by light soaking. To investigate the underlying mechanism, corona charge experiments are carried out on p-type c-Si samples before and after light soaking. The results indicate that the negative fixed charge density Qf present in the Al2O3 films increases due to the light soaking, which results in an improved field-effect passivation. Numerical calculations also confirm that the improved field-effect passivation is the main contributor for the increased effective lifetime after light soaking. To further understand the light soaking phenomenon, a kinetic model—a charge trapping/de-trapping model—is proposed to explain the time dependent behavior of the lifetime increase/decrease observed under/after light soaking. The trap model fits the experimental results very well. The observed light enhanced passivation for ALD Al2O3 passivated c-Si is of technological relevance, because solar cell devices operate under illumination, thus an increase in solar cell efficiency due to light soaking can be expected.

Sustainable synthesis of metals-doped ZnO nanoparticles from zinc-bearing dust for photodegradation of phenol.

PubMed

Wu, Zhao-Jin; Huang, Wei; Cui, Ke-Ke; Gao, Zhi-Fang; Wang, Ping

2014-08-15

A novel strategy of waste-cleaning-waste is proposed in the present work. A metals-doped ZnO (M-ZnO, M = Fe, Mg, Ca and Al) nanomaterial has been prepared from a metallurgical zinc-containing solid waste "fabric filter dust" by combining sulfolysis and co-precipitation processes, and is found to be a favorable photocatalyst for photodegradation of organic substances in wastewater under visible light irradiation. All the zinc and dopants (Fe, Mg, Ca and Al) for preparing M-ZnO are recovered from the fabric filter dust, without any addition of chemical as elemental source. The dust-derived M-ZnO samples deliver single phase indexed as the hexagonal ZnO crystal, with controllable dopants species. The photocatalytic activity of the dust-derived M-ZnO samples is characterized by photodegradation of phenol aqueous solution under visible light irradiation, giving more prominent photocatalytic behaviors than undoped ZnO. Such enhancements may be attributed to incorporation of the dust-derived metal elements (Fe, Mg, Ca and Al) into ZnO structure, which lead to the modification of band gap and refinement of grain size. The results show a feasibility to utilize the industrial waste as a resource of photodegradating organic substances in wastewater treatments. Copyright © 2014 Elsevier B.V. All rights reserved.

Resonant cavity light-emitting diodes based on dielectric passive cavity structures

NASA Astrophysics Data System (ADS)

Ledentsov, N.; Shchukin, V. A.; Kropp, J.-R.; Zschiedrich, L.; Schmidt, F.; Ledentsov, N. N.

2017-02-01

A novel design for high brightness planar technology light-emitting diodes (LEDs) and LED on-wafer arrays on absorbing substrates is proposed. The design integrates features of passive dielectric cavity deposited on top of an oxide- semiconductor distributed Bragg reflector (DBR), the p-n junction with a light emitting region is introduced into the top semiconductor λ/4 DBR period. A multilayer dielectric structure containing a cavity layer and dielectric DBRs is further processed by etching into a micrometer-scale pattern. An oxide-confined aperture is further amended for current and light confinement. We study the impact of the placement of the active region into the maximum or minimum of the optical field intensity and study an impact of the active region positioning on light extraction efficiency. We also study an etching profile composed of symmetric rings in the etched passive cavity over the light emitting area. The bottom semiconductor is an AlGaAs-AlAs multilayer DBR selectively oxidized with the conversion of the AlAs layers into AlOx to increase the stopband width preventing the light from entering the semiconductor substrate. The approach allows to achieve very high light extraction efficiency in a narrow vertical angle keeping the reasonable thermal and current conductivity properties. As an example, a micro-LED structure has been modeled with AlGaAs-AlAs or AlGaAs-AlOx DBRs and an active region based on InGaAlP quantum well(s) emitting in the orange spectral range at 610 nm. A passive dielectric SiO2 cavity is confined by dielectric Ta2O5/SiO2 and AlGaAs-AlOx DBRs. Cylindrically-symmetric structures with multiple ring patterns are modeled. It is demonstrated that the extraction coefficient of light to the air can be increased from 1.3% up to above 90% in a narrow vertical angle (full width at half maximum (FWHM) below 20°). For very small oxide-confined apertures 100nm the narrowing of the FWHM for light extraction can be reduced down to 5°. Consequently high efficiency high brightness arrays of micro-LEDs becomes possible. For single emitters the approach is particularly interesting for oscillator strength engineering allowing high speed data transmission and for single photonics applying single quantum dot (QD) emitters and allowing >90% coupling of the emission into single mode fiber. We also note that for longer wavelength ( 1300nm) QDs the thickness of the layers and surface patterns significantly increase allowing greatly reduced processing tolerances and applying further simplifications due to the possibility of using high contrast GaAs-AlOx DBRs.

Deposition and thermal characterization of nano-structured aluminum nitride thin film on Cu-W substrate for high power light emitting diode package.

PubMed

Cho, Hyun Min; Kim, Min-Sun

2014-08-01

In this study, we developed AlN thick film on metal substrate for hybrid type LED package such as chip on board (COB) using metal printed circuit board (PCB). Conventional metal PCB uses ceramic-polymer composite as electrical insulating layer. Thermal conductivities of such type dielectric film are typically in the range of 1~4 W/m · K depending on the ceramic filler. Also, Al or Cu alloy are mainly used for metal base for high thermal conduction to dissipate heat from thermal source mounted on metal PCB. Here we used Cu-W alloy with low thermal expansion coefficient as metal substrate to reduce thermal stress between insulating layer and base metal. AlN with polyimide (PI) powder were used as starting materials for deposition. We could obtain very high thermal conductivity of 28.3 W/m · K from deposited AlN-PI thin film by AlN-3 wt% PI powder. We made hybrid type high power LED package using AlN-PI thin film. We tested thermal performance of this film by thermal transient measurement and compared with conventional metal PCB substrate.

Synthesis and luminescent properties of Gd3Ga2Al3O12 phosphors doped with Eu3+ or Ce3+

NASA Astrophysics Data System (ADS)

Oh, M. J.; Kim, H. J.

2016-09-01

Eu3+-or Ce3+-doped gadolinium gallium aluminum garnet (GGAG), Gd3Ga2Al3O12, phosphors are fabricated using solid-state reactions with Gd2O3, Ga2O3, Al2O3, CeO2 and Eu2O3 powders. The Eu3+-or Ce3+-doped Gd3Ga2Al3O12 phosphors are sintered at 1300 °C or 1600 °C for 5 hours by using an electric furnace under normal atmosphere. X-ray diffraction and field-emission scanning electron microscopy studies are carried out in order to analyze the physical properties of these materials, and their luminescence properties are also measured by using UV and X-ray sources. The Eu3+-or Ce3+-doped Gd3Ga2Al3O12 phosphors show higher light yields in comparison to commercial phosphors such as Gd2O2S:Tb (gadox). This indicates that Gd3Ga2Al3O12:Eu3+ phosphors are promising materials for use in X-ray imaging and dose monitoring at proton beamlines.

High power laser-driven ceramic phosphor plate for outstanding efficient white light conversion in application of automotive lighting

PubMed Central

Song, Young Hyun; Ji, Eun Kyung; Jeong, Byung Woo; Jung, Mong Kwon; Kim, Eun Young; Yoon, Dae Ho

2016-01-01

We report on Y3Al5O12: Ce3+ ceramic phosphor plate (CPP) using nano phosphor for high power laser diode (LD) application for white light in automotive lighting. The prepared CPP shows improved luminous properties as a function of Ce3+ concentration. The luminous properties of the Y3Al5O12: Ce3+ CPP nano phosphor are improved when compared to the Y3Al5O12: Ce3+ CPP with bulk phosphor, and hence, the luminous emittance, luminous flux, and conversion efficiency are improved. The Y3Al5O12: Ce3+ CPP with an optimal Ce3+ content of 0.5 mol % shows 2733 lm/mm2 value under high power blue radiant flux density of 19.1 W/mm2. The results indicate that Y3Al5O12: Ce3+ CPP using nano phosphor can serve as a potential material for solid-state laser lighting in automotive applications. PMID:27502730

High power laser-driven ceramic phosphor plate for outstanding efficient white light conversion in application of automotive lighting.

PubMed

Song, Young Hyun; Ji, Eun Kyung; Jeong, Byung Woo; Jung, Mong Kwon; Kim, Eun Young; Yoon, Dae Ho

2016-08-09

We report on Y3Al5O12: Ce(3+) ceramic phosphor plate (CPP) using nano phosphor for high power laser diode (LD) application for white light in automotive lighting. The prepared CPP shows improved luminous properties as a function of Ce(3+) concentration. The luminous properties of the Y3Al5O12: Ce(3+) CPP nano phosphor are improved when compared to the Y3Al5O12: Ce(3+) CPP with bulk phosphor, and hence, the luminous emittance, luminous flux, and conversion efficiency are improved. The Y3Al5O12: Ce(3+) CPP with an optimal Ce(3+) content of 0.5 mol % shows 2733 lm/mm(2) value under high power blue radiant flux density of 19.1 W/mm(2). The results indicate that Y3Al5O12: Ce(3+) CPP using nano phosphor can serve as a potential material for solid-state laser lighting in automotive applications.

Performance improvement of AlGaN-based deep-ultraviolet light-emitting diodes via Al-composition graded quantum wells

NASA Astrophysics Data System (ADS)

Lu, Lin; Zhang, Yu; Xu, Fujun; Ding, Gege; Liu, Yuhang

2018-06-01

Characteristics of AlGaN-based deep-ultraviolet light-emitting diodes (DUV-LEDs) with step-like and Al-composition graded quantum wells have been investigated. The simulation results show that compared to DUV-LEDs with the conventional AlGaN multiple quantum wells (MQWs) structure, the light output power (LOP) and efficiency droop of DUV-LEDs with the Al-composition graded wells were remarkably improved. The key factor accounting for the improved performance is ascribed to the better modulation of carrier distribution in the quantum wells to increase the overlap between electron and hole wavefunctions, which contributes to more efficient recombination of electrons and holes, and thereby a significant enhancement in the LOP.

High extraction efficiency ultraviolet light-emitting diode

DOEpatents

Wierer, Jonathan; Montano, Ines; Allerman, Andrew A.

2015-11-24

Ultraviolet light-emitting diodes with tailored AlGaN quantum wells can achieve high extraction efficiency. For efficient bottom light extraction, parallel polarized light is preferred, because it propagates predominately perpendicular to the QW plane and into the typical and more efficient light escape cones. This is favored over perpendicular polarized light that propagates along the QW plane which requires multiple, lossy bounces before extraction. The thickness and carrier density of AlGaN QW layers have a strong influence on the valence subband structure, and the resulting optical polarization and light extraction of ultraviolet light-emitting diodes. At Al>0.3, thinner QW layers (<2.5 nm are preferred) result in light preferentially polarized parallel to the QW plane. Also, active regions consisting of six or more QWs, to reduce carrier density, and with thin barriers, to efficiently inject carriers in all the QWs, are preferred.

AlGaInAs EML having high extinction ratios fabricated by identical epitaxial layer technique

NASA Astrophysics Data System (ADS)

Deng, Qiufang; Guo, Lu; Liang, Song; Sun, Siwei; Xie, Xiao; Zhu, Hongliang; Wang, Wei

2018-04-01

AlGaInAs electroabsorption-modulated lasers (EMLs) fabricated by identical epitaxial layer technique are demonstrated. The EML device shows an infinite characteristic temperature when the temperature ranges from 20 oC to 30 oC. The integrated modulator has static extinction ratios of larger than 20 dB at a reverse bias voltage of - 2 V. The small signal modulation bandwidth of the modulator is larger than 11 GHz. At 10 Gb/s data modulation, the dynamic extinction ratio is about 9.5 dB in a back to back test configuration. Because only a simple fabrication procedure is needed, our EMLs are promising low cost light sources for optical fiber transmission applications.

Effects of GaN/AlGaN/Sputtered AlN nucleation layers on performance of GaN-based ultraviolet light-emitting diodes

PubMed Central

Hu, Hongpo; Zhou, Shengjun; Liu, Xingtong; Gao, Yilin; Gui, Chengqun; Liu, Sheng

2017-01-01

We report on the demonstration of GaN-based ultraviolet light-emitting diodes (UV LEDs) emitting at 375 nm grown on patterned sapphire substrate (PSS) with in-situ low temperature GaN/AlGaN nucleation layers (NLs) and ex-situ sputtered AlN NL. The threading dislocation (TD) densities in GaN-based UV LEDs with GaN/AlGaN/sputtered AlN NLs were determined by high-resolution X-ray diffraction (XRD) and cross-sectional transmission electron microscopy (TEM), which revealed that the TD density in UV LED with AlGaN NL was the highest, whereas that in UV LED with sputtered AlN NL was the lowest. The light output power (LOP) of UV LED with AlGaN NL was 18.2% higher than that of UV LED with GaN NL owing to a decrease in the absorption of 375 nm UV light in the AlGaN NL with a larger bandgap. Using a sputtered AlN NL instead of the AlGaN NL, the LOP of UV LED was further enhanced by 11.3%, which is attributed to reduced TD density in InGaN/AlInGaN active region. In the sputtered AlN thickness range of 10–25 nm, the LOP of UV LED with 15-nm-thick sputtered AlN NL was the highest, revealing that optimum thickness of the sputtered AlN NL is around 15 nm. PMID:28294166

Light Converting Inorganic Phosphors for White Light-Emitting Diodes

PubMed Central

Chen, Lei; Lin, Chun-Che; Yeh, Chiao-Wen; Liu, Ru-Shi

2010-01-01

White light-emitting diodes (WLEDs) have matched the emission efficiency of florescent lights and will rapidly spread as light source for homes and offices in the next 5 to 10 years. WLEDs provide a light element having a semiconductor light emitting layer (blue or near-ultraviolet (nUV) LEDs) and photoluminescence phosphors. These solid-state LED lamps, rather than organic light emitting diode (OLED) or polymer light-emitting diode (PLED), have a number of advantages over conventional incandescent bulbs and halogen lamps, such as high efficiency to convert electrical energy into light, reliability and long operating lifetime. To meet with the further requirement of high color rendering index, warm light with low color temperature, high thermal stability and higher energy efficiency for WLEDs, new phosphors that can absorb excitation energy from blue or nUV LEDs and generate visible emissions efficiently are desired. The criteria of choosing the best phosphors, for blue (450−480 nm) and nUV (380−400 nm) LEDs, strongly depends on the absorption and emission of the phosphors. Moreover, the balance of light between the emission from blue-nUV LEDs and the emissions from phosphors (such as yellow from Y3Al5O12:Ce3+) is important to obtain white light with proper color rendering index and color temperature. Here, we will review the status of phosphors for LEDs and prospect the future development.

AMS+ALS: Kinetic and Product Studies of the Heterogeneous Oxidation of Organic Aerosol at the Advanced Light Source

NASA Astrophysics Data System (ADS)

Kroll, J. H.; Wilson, K. R.; Kessler, S. H.; Browne, E. C.; Nah, T.; Smith, J.; Worsnop, D. R.

2014-12-01

The atmospheric oxidation of condensed-phase organic species can have a major influence on the composition, properties, and impacts of organic aerosol (OA); however the rates and products of such "aging" reactions are poorly constrained. Here we describe a series of laboratory experiments aimed at better understanding one class of aging reactions, the heterogeneous oxidation of OA by gas-phase oxidants. Central to these experiments is the availability of vacuum ultraviolet (VUV) light at the Chemical Dynamics Beamline of the Advanced Light Source at LBNL, which enables the implementation of VUV photoionization aerosol mass spectrometry. This technique allows for the real-time, speciated measurement of OA composition, yielding molecular information that is highly complementary to ensemble data from electron-impact ionization. OA composition is measured with both ionization schemes as a function of oxidant exposure within a flow reactor, providing detailed information on the kinetics and products of heterogeneous oxidation over multiple generations of oxidation. Specific topics investigated include the branching between functionalization and fragmentation of OA components, the formation of secondary organic aerosol from photolytically-generated radical species, and the heterogeneous aging of soot-associated organic species.

Infrared thermography for inspecting of pipeline specimen

NASA Astrophysics Data System (ADS)

Chen, Dapeng; Li, Xiaoli; Sun, Zuoming; Zhang, Xiaolong

2018-02-01

Infrared thermography is a fast and effective non-destructive testing method, which has an increasing application in the field of Aeronautics, Astronautic, architecture and medical, et al. Most of the reports about the application of this technology are focus on the specimens of planar, pulse light is often used as the heat stimulation and a plane heat source is generated on the surface of the specimen by the using of a lampshade, however, this method is not suitable for the specimen of non-planar, such as the pipeline. Therefore, in this paper, according the NDT problem of a steel and composite pipeline specimen, ultrasonic and hot water are applied as the heat source respectively, and an IR camera is used to record the temperature varies of the surface of the specimen, defects are revealed by the thermal images sequence processing. Furthermore, the results of light pulse thermography are also shown as comparison, it is indicated that choose the right stimulation method, can get a more effective NDT results for the pipeline specimen.

Few-Layer WSe2 Schottky Junction-Based Photovoltaic Devices through Site-Selective Dual Doping.

PubMed

Ko, Seungpil; Na, Junhong; Moon, Young-Sun; Zschieschang, Ute; Acharya, Rachana; Klauk, Hagen; Kim, Gyu-Tae; Burghard, Marko; Kern, Klaus

2017-12-13

Ultrathin sheets of two-dimensional (2D) materials like transition metal dichalcogenides have attracted strong attention as components of high-performance light-harvesting devices. Here, we report the implementation of Schottky junction-based photovoltaic devices through site-selective surface doping of few-layer WSe 2 in lateral contact configuration. Specifically, whereas the drain region is covered by a strong molecular p-type dopant (NDP-9) to achieve an Ohmic contact, the source region is coated with an Al 2 O 3 layer, which causes local n-type doping and correspondingly an increase of the Schottky barrier at the contact. By scanning photocurrent microscopy using green laser light, it could be confirmed that photocurent generation is restricted to the region around the source contact. The local photoinduced charge separation is associated with a photoresponsivity of up to 20 mA W -1 and an external quantum efficiency of up to 1.3%. The demonstrated device concept should be easily transferrable to other van der Waals 2D materials.

Femtosecond synchronism of x-rays and visible/infrared light in an x-ray free-electron laser

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

Adams, B. W.

2007-12-15

A way is proposed to obtain ultrashort pulses of intense infrared/visible light in few-femtosecond synchronism with x-rays from an x-ray free-electron laser (XFEL). It makes use of the recently proposed emittance-slicing technique [Emma et al., Phys. Rev. Lett. 92, 074801 (2004)] to both restrict the duration of self-amplified spontaneous emission (SASE) to a few femtoseconds and to lead to a coherence enhancement of near-infrared transition undulator radiation (CTUR). The x-rays and the near-infrared light originate within the XFEL undulator from the same slice of electrons within a bunch and are therefore perfectly synchronized with each other. An example of realizingmore » the scheme at the Linac Coherent Light Source is presented. A few side issues are explored briefly, such as the magnitude of the velocity term versus the acceleration term in the Lienard-Wiechert fields and the possible use of the CTUR as a diagnostic tool for the SASE process itself.« less

Storing hydrogen in the form of light alloy hydrides

NASA Technical Reports Server (NTRS)

Freund, E.; Gillerm, C.

1981-01-01

Different hydrides are investigated to find a system with a sufficiently high storage density (at least 3%). The formation of hydrides with light alloys is examined. Reaction kinetics for hydride formation were defined and applied to the systems Mg-Al-H, Mg-Al-Cu-H, Ti-Al-H, Ti-Al-Cu-H, and Ti-Al-Ni-H. Results indicate that the addition of Al destabilizes MgH2 and TiH2 hydrides while having only a limited effect on the storage density.

Black Carbon at the Mt. Bachelor Observatory Field Campaign Report

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

Jaffe, Dan A.; Sedlacek, Arthur; Laing, James R.

This campaign was initiated to measure refractory black carbon (rBC, as defined in Schwarz et al. (2010)) at the Mt. Bachelor Observatory (MBO) using the U.S. Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) Climate Research Facility single-particle soot photometer (SP2; unit 54). MBO is a high-elevation site located on the summit of Mt. Bachelor in central Oregon, USA (43.979°N, 121.687°W, 2,763 meters ASL). This site is operated by Professor Dan Jaffe’s group at the University of Washington Bothell and has been used continuously as an atmospheric observatory for the past 12 years (Jaffe et al., 2005; Gratz et al.,more » 2014). The location of MBO allows frequent sampling of the free troposphere along with a wide array of plumes from regional and distant sources. MBO is currently supported with funding from the National Science Foundation (NSF) to the Principal Investigator (PI; D. Jaffe) via the project “Influence of Free Tropospheric Ozone and PM on Surface Air Quality in the Western U.S.” (#1447832) covering the period 03/15/2015 to 02/28/2018. The SP2 instrument from Droplet Measurement Technologies provides particle-resolved measurements of rBC mass loading, size and mass distributions, and mixing state. The SP2 was installed at MBO on 6/27/2016 and ran through 9/23/2016. Additional measurements at MBO during this campaign included carbon monoxide (CO), fine particulate matter (PM1), aerosol light scattering coefficients (σscat) at three wavelengths using a TSI nephelometer, aerosol absorption coefficients (σabs) with the Brechtel tricolor absorption photometer (TAP), aerosol number size distributions with a scanning mobility particle sizer spectrometer (SMPS), and black carbon (eBC) with an aethalometer. BC data from this campaign have been submitted to the ARM Data Archive. Black carbon (BC) is the predominant light-absorbing aerosol constituent in the atmosphere, and is estimated to exert a positive radiative forcing second only to CO 2 (Ramanathan and Carmichael, 2008). One of the largest sources of BC globally is biomass burning (BB). (Akagi et al., 2011; Andreae and Merlet, 2001; Bond et al., 2013; Bond et al., 2004; Reid et al., 2005b): a source that is likely to increase in the Western U.S. due to climate change (Dennison et al., 2014; Abatzoglon and Williams, 2016; Westerling et al., 2006). Given the likely increased role of BB aerosol in atmospheric forcing, we need to improve our understanding of the physical and optical properties of aged BB aerosol. During the SP2 deployment period at MBO we observed seven BB events, all of which originated from the Gap Fire in Northern California, which burned 33,867 acres in the Klamath National Forest (https://inciweb.nwcg.gov/incident/4997/). Heavy smoke plumes from this fire were transported to MBO from 8/29/2016 to 8/31/2016. We calculated back-trajectories using the National Oceanic and Atmospheric Administration (NOAA) Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model, version 4 (Draxler, 1999; Draxler and Hess, 1997, 1998; Stein et al., 2015) to confirm transport from the fire locations to MBO. We identified the fire locations using moderate resolution imaging spectroradiometer (MODIS) satellite-derived active fire counts (Justice et al., 2002). Transport time for all of the BB events ranged from 8 to 32 hours.« less

Sources of Water-soluble Organic Aerosol in the Southeastern United States - Evidence of SOA Formed Through Heterogeneous Reactions

NASA Astrophysics Data System (ADS)

Zhang, X.; Weber, R. J.

2010-12-01

Recent laboratory studies suggest partitioning of semi-volatile organic compounds (SVOCs) to liquid water followed by heterogeneous chemical transformation as a possible route to forming secondary organic aerosol (SOA). This paper will present results from observational studies of SOA formation using Water-Soluble Organic Carbon (WSOC) fraction of SOA, soluble brown carbon (e.g., light absorption spectra), organic acids and a number of aerosol source tracers in the Southeastern U.S., a region known for extensive biogenic and anthropogenic VOC emissions. Based on 24-h integrated filter measurements at 15 sites in the southeast throughout the year of 2007, a PMF analysis identified a factor characterized by the co-abundance of WSOC (58 percent of the total), oxalate (51 percent) and brown carbon (Abs365) (44 percent), which is consistent with the aqueous phase SOA formation mechanism in which water-soluble organic products from gas-phase photochemistry dissolve in liquid (fog/cloud droplets or particle water) and react further to form oligomers, light absorbing compounds, and light-weight organic acids, with oxalic acid being the most abundant one [Hecobian et al., 2010; Zhang et al., 2010]. The temporal variability of this factor correlated well with ambient temperature, possibly owing to the large impact from biogenic emissions, which are dependent on temperature and known to be significant over the southeast. PMF analysis of other data sets collected in Atlanta with online instruments during summer support these findings; as do other studies based on different data sets and data-analysis methods [Hennigan et al., 2008a; Hennigan et al., 2008b; Hennigan et al., 2008c; Hennigan et al., 2009]. Overall, we find that WSOC is largely secondary (roughly 75 to 85 percent) and estimate that 65 to 75 percent of the secondary WSOC formed in the southeast involves some form of aqueous phase chemical process. Hecobian, A., X. Zhang, M. Zheng, N. Frank, E. S. Edgerton, and R. J. Weber (2010), Water-soluble organic aerosol material and the light-absorption characteristics of aqueous extracts measured over the southeastern United States, Atm. Chem. Phys., 10, 5965-5977. Hennigan, C. J., M. H. Bergin, J. E. Dibb, and R. J. Weber (2008a), Enhanced secondary organic aerosol formation due to water uptake by fine particles, Geophys. Res. Lett., 35, L18801, 18810.11029/12008GL035046. Hennigan, C. J., M. H. Bergin, and R. J. Weber (2008b), Correlations between water-soluble organic aerosol and water vapor: A synergistic effect from biogenic emissions?, Environ. Sci. Tech., 42(24), 9079-9085. Hennigan, C. J., et al. (2008c), On the volatility and production mechanisms of newly formed nitrate and water soluble organic aerosol in Mexico City, Atm. Chem. Phys., 8, 3761-3768. Hennigan, C. J., M. H. Bergin, A. G. Russell, A. Nenes, and R. J. Weber (2009), Gas/particle partitioning of water-soluble organic aerosol in Atlanta, Atm. Chem. Phys., 9, 3613-3628. Zhang, X., A. Hecobian, M. Zheng, N. Frank, and R. J. Weber (2010), Biomass buring impact on PM2.5 over the southeastern U.S.: Intgrating chemically speciated FRM filter measurements, MODIS fire counts and PMF analysis, Atm. Chem. Phys., 10, 6839-6853.

Assessment of In Situ Time Resolved Shock Experiments at Synchrotron Light Sources*

NASA Astrophysics Data System (ADS)

Belak, J.; Ilavsky, J.; Hessler, J. P.

2005-07-01

Prior to fielding in situ time resolved experiments of shock wave loading at the Advanced Photon Source, we have performed feasibility experiments assessing a single photon bunch. Using single and poly-crystal Al, Ti, V and Cu shock to incipient spallation on the gas gun, samples were prepared from slices normal to the spall plane of thickness 100-500 microns. In addition, single crystal Al of thickness 500 microns was shocked to incipient spallation and soft recovered using the LLNL e-gun mini-flyer system. The e-gun mini-flyer impacts the sample target producing a 10's ns flat-top shock transient. Here, we present results for imaging, small-angle scattering (SAS), and diffraction. In particular, there is little SAS away from the spall plane and significant SAS at the spall plane, demonstrating the presence of sub-micron voids. * Use of the Advanced Photon Source was supported by the U. S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. W-31-109-Eng-38 and work performed under the auspices of the U.S. Department of Energy by University of California, Lawrence Livermore National Laboratory under Contract W-7405-Eng-48.

Complex topological structures of frustrated liquid crystals with potential for optics and photonics (Presentation Recording)

NASA Astrophysics Data System (ADS)

Žumer, Slobodan; Čančula, Miha; Čopar, Simon; Ravnik, Miha

2015-10-01

Geometrical constrains and intrinsic chirality in nematic mesophases enable formation of stable and metastable complex defect structures. Recently selected knotted and linked disclinations have been formed using laser manipulation of nematic braids entangling colloidal particles in nematic colloids [Tkalec et al., Science 2011; Copar et al., PNAS 2015]. In unwinded chiral nematic phases stable and metastable toron and hopfion defects have been implemented by laser tweezers [Smalyukh et al., Nature Materials 2010; Chen et al., PRL2013] and in chiral nematic colloids particles dressed by solitonic deformations [Porenta et al., Sci. Rep. 2014]. Modelling studies based on the numerical minimisation of the phenomenological free energy, supported with the adapted topological theory [Copar and Zumer, PRL 2011; Copar, Phys. Rep. 2014] allow describing the observed nematic defect structures and also predicting numerous structures in confined blue phases [Fukuda and Zumer, Nature Comms 2011 and PRL 2011] and stable knotted disclinations in cholesteric droplets with homeotropic boundary [Sec et al., Nature Comms 2014]. Coupling the modeling with finite difference time domain light field computation enables understanding of light propagation and light induced restructuring in these mesophases. The method was recently demonstrated for the description of low intensity light beam changes during the propagation along disclination lines [Brasselet et al., PRL 2009; Cancula et al., PRE 2014]. Allowing also high intensity light an order restructuring is induced [Porenta et al., Soft Matter 2012; Cancula et al., 2015]. These approaches help to uncover the potential of topological structures for beyond-display optical and photonic applications.

Applications of Fiber Optics in Experimental Mechanics

DTIC Science & Technology

1987-01-01

or-plane component of vibration. This fiber optic "Ham,7 Cuomo’ and Hoogenboom et al.9 In all array system was claimcd to be capable or a frequency...mechanical action and CTeeCtiVrly reduce the I3alexavllent p esropationg aong the inthecont f fiber. ( y prvids a microbending induced by the deformer. On a...transmit light as a source of poIer sufficient to directly activate mechanical phenomena. R41 tIdd F . and rurek, P. A.. "’Single Nildl Iithr-O)pti

Popular Berkeley Lab X-ray Data Booklet reissued

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

Robinson, Art

2001-03-02

X-ray scientists and synchrotron-radiation users who have been patiently waiting for an updated version of the popular X-Ray Data Booklet last published in 1986 by the Center for X-Ray Optics at the Lawrence Berkeley National Laboratory can breathe a sigh of relief. The venerable ''little orange book'' has now been reissued under the auspices of CXRO and the Advanced Light Source (ALS) with an April printing of 10,000 paper copies and the posting of a Web edition at http://xdb.lbl.gov.

High-Speed High-Efficiency Large-Area Resonant Cavity Enhanced p-i-n Photodiodes for Multimode Fiber Communications

DTIC Science & Technology

2001-12-01

850 nm. The layers are grown by molecular beam epitaxy . The AlGaAs–GaAs inter- faces are alloy-graded for 30 nm to eliminate charge trapping that may... beam of the VCSELs allow for easy coupling of light into the MMF, it is also desirable to have photodetectors with large active windows compatible with... VCSEL )emitting at 850 nm [1] have become the preferred source for high-speed short-wavelength communication systems. These VCSELs are particularly

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.

PubMed

Miranda, Geraldo Elias; Melani, Rodolfo Francisco Haltenhoff; Francisquini, Luiz; Daruge, Eduardo

2017-01-01

The aim of this study was to identify the combination of wavelength and filter that best detects tooth and bone, and to determine which biological materials (enamel, dental root or bone) have highest fluorescence intensity when exposed to an alternate light source (ALS). Tooth and bone samples were lighted with ALS and photographed. Adobe Photoshop™ and ImageJ™ softwares were used for image analysis. Data obtained by measuring the photograph pixels were subjected to analysis of variance. The mean values of significant effects were compared by the Tukey test. In all tests, the significance level was set at p≤0.05 and the values calculated by the SAS system. The results showed that the best combination for detecting tooth and bone is an illumination wavelength of 455 nm with an orange filter. The fluorescence of dental root is greater than that of enamel, which in turn is greater than that of bone. The biological material had markedly higher fluorescence than the inert material. This knowledge can help the forensic expert to screen and detect biological materials, for example in situations where there are fragmented teeth and small bones, both at the scene and in the laboratory.

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

Guo, Wei, E-mail: wguo2@ncsu.edu; Kirste, Ronny; Bryan, Zachary

Enhanced light extraction efficiency was demonstrated on nanostructure patterned GaN and AlGaN/AlN Multiple-Quantum-Well (MQW) structures using mass production techniques including natural lithography and interference lithography with feature size as small as 100 nm. Periodic nanostructures showed higher light extraction efficiency and modified emission profile compared to non-periodic structures based on integral reflection and angular-resolved transmission measurement. Light extraction mechanism of macroscopic and microscopic nanopatterning is discussed, and the advantage of using periodic nanostructure patterning is provided. An enhanced photoluminescence emission intensity was observed on nanostructure patterned AlGaN/AlN MQW compared to as-grown structure, demonstrating a large-scale and mass-producible pathway to higher lightmore » extraction efficiency in deep-ultra-violet light-emitting diodes.« less

Comparison of Muon Capture in Light and in Heavy Nuclei

NASA Astrophysics Data System (ADS)

Measday, David F.; Stocki, Trevor J.

2007-10-01

We have recently completed an experimental study at TRIUMF of muon capture in the following elements, N, Al, Si, Ca, Fe, Ni, I, Au, and Bi. We detected the nuclear gamma rays emitted by the product nuclei after muon capture. The energy of the gamma ray identifies the source nuclide, and thus the reaction which has occurred. Our data are of better quality, and more comprehensive than any other data set in the literature. The (μ-,νn) reaction is always dominant. In light nuclei, reactions such as (μ-,νp) and (μ-,νpn) can occur, but not for heavy nuclei. However the reverse is true for reactions such as (μ-,ν3n) and (μ-,ν4n), which are very rare in light nuclei, but easily detected in heavy elements. We shall discuss how such information can be useful in calculations of neutrino-nucleus interactions, and of electron-capture in supernovae.

Improved High-Energy Response of AlGaAs/GaAs Solar Cells Using a Low-Cost Technology

NASA Astrophysics Data System (ADS)

Noorzad, Camron D.; Zhao, Xin; Harotoonian, Vache; Woodall, Jerry M.

2016-12-01

We report on an AlGaAs/GaAs solar cell with a significantly increased high-energy response that was produced via a modified liquid phase epitaxy (LPE) technique. This technique uses a one-step process in which the solid-liquid equilibrium Al-Ga-As:Zn melt in contact with an n-type vendor GaAs substrate simultaneously getters impurities in the substrate that shorten minority carrier lifetimes, diffuses Zn into the substrate to create a p- n junction, and forms a thin p-AlGaAs window layer that enables more high-energy light to be efficiently absorbed. Unlike conventional LPE, this process is performed isothermally. In our "double Al" method, the ratio of Al in the melt ("Al melt ratio") that was used in our process was two times more than what was previously reported in the record 1977 International Business Machines (IBM) solar cell. Photoluminescence (PL) results showed our double Al sample yielded a response to 405 nm light ("blue light"), which was more than twice as intense as the response from our replicated IBM cell. The original 1977 cell had a low-intensity spectral response to photon wavelengths under 443 nm (Woodall and Hovel in Sol Energy Mater Sol Cells 29:176, 1990). Secondary ion mass spectrometry results confirmed the increased blue light response was due to a large reduction in AlGaAs window layer thickness. These results proved increasing the Al melt ratio broadens the spectrum of light that can be transmitted through the window layer into the active GaAs region for absorption, increasing the overall solar cell efficiency. Our enhanced double Al method can pave the way for large-scale manufacturing of low-cost, high-efficiency solar cells.

High pressure single-crystal micro X-ray diffraction analysis with GSE_ADA/RSV software

NASA Astrophysics Data System (ADS)

Dera, Przemyslaw; Zhuravlev, Kirill; Prakapenka, Vitali; Rivers, Mark L.; Finkelstein, Gregory J.; Grubor-Urosevic, Ognjen; Tschauner, Oliver; Clark, Simon M.; Downs, Robert T.

2013-08-01

GSE_ADA/RSV is a free software package for custom analysis of single-crystal micro X-ray diffraction (SCμXRD) data, developed with particular emphasis on data from samples enclosed in diamond anvil cells and subject to high pressure conditions. The package has been in extensive use at the high pressure beamlines of Advanced Photon Source (APS), Argonne National Laboratory and Advanced Light Source (ALS), Lawrence Berkeley National Laboratory. The software is optimized for processing of wide-rotation images and includes a variety of peak intensity corrections and peak filtering features, which are custom-designed to make processing of high pressure SCμXRD easier and more reliable.

75 FR 21048 - Northern Lights Fund Trust, et al.; Notice of Application

Federal Register 2010, 2011, 2012, 2013, 2014

2010-04-22

... SECURITIES AND EXCHANGE COMMISSION [Investment Company Act Release No. 29208; 812-13651] Northern Lights Fund Trust, et al.; Notice of Application April 16, 2010. AGENCY: Securities and Exchange... shareholder approval and would grant relief from certain disclosure requirements. Applicants: Northern Lights...

The Experimental Demonstration of High Efficiency Interaction-free Measurement for Quantum Counterfactual-like Communication.

PubMed

Liu, Chao; Liu, Jinhong; Zhang, Junxiang; Zhu, Shiyao

2017-09-07

We present an interaction-free measurement with quantum Zeno effect and a high efficiency η = 74.6% ± 0.15%. As a proof-of-principle demonstration, this measurement can be used to implement a quantum counterfactual-like communication protocol. Instead of a single photon state, we use a coherent light as the input source and show that the output agrees with the proposed quantum counterfactual communication protocol according to Salih et al. Although the counterfactuality is not achieved due to the presence of a few photons in the public channel, we show that the signal light is nearly absent in the public channel, which exhibits a proof-of-principle quantum counterfactual-like property of communication.

Atomic pair distribution function at the Brazilian Synchrotron Light Laboratory: application to the Pb 1–x La xZr 0.40Ti 0.60O 3 ferroelectric system

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

Saleta, M. E.; Eleotério, M.; Mesquita, A.

2017-07-29

This work reports the setting up of the X-ray diffraction and spectroscopy beamline at the Brazilian Synchrotron Light Laboratory for performing total scattering experiments to be analyzed by atomic pair distribution function (PDF) studies. The results of a PDF refinement for Al 2O 3 standard are presented and compared with data acquired at a beamline of the Advanced Photon Source, where it is common to perform this type of experiment. A preliminary characterization of the Pb 1–xLa xZr 0.40Ti 0.60O 3 ferroelectric system, withx= 0.11, 0.12 and 0.15, is also shown.

Lattice-matched double dip-shaped BAlGaN/AlN quantum well structures for ultraviolet light emission devices

NASA Astrophysics Data System (ADS)

Park, Seoung-Hwan; Ahn, Doyeol

2018-05-01

Ultraviolet light emission characteristics of lattice-matched BxAlyGa1-x-y N/AlN quantum well (QW) structures with double AlGaN delta layers were investigated theoretically. In contrast to conventional single dip-shaped QW structure where the reduction effect of the spatial separation between electron and hole wave functions is negligible, proposed double dip-shaped QW shows significant enhancement of the ultraviolet light emission intensity from a BAlGaN/AlN QW structure due to the reduced spatial separation between electron and hole wave functions. The emission peak of the double dip-shaped QW structure is expected to be about three times larger than that of the conventional rectangular AlGaN/AlN QW structure.

The Physics and Applications of High Brightness Electron Beams

NASA Astrophysics Data System (ADS)

Palumbo, Luigi; Rosenzweig, J.; Serafini, Luca

2007-09-01

Plenary sessions. RF deflector based sub-Ps beam diagnostics: application to FEL and advanced accelerators / D. Alesini. Production of fermtosecond pulses and micron beam spots for high brightness electron beam applications / S.G. Anderson ... [et al.]. Wakefields of sub-picosecond electron bunches / K.L.F. Bane. Diamond secondary emitter / I. Ben-Zvi ... [et al.]. Parametric optimization for an X-ray free electron laser with a laser wiggler / R. Bonifacio, N. Piovella and M.M. Cola. Needle cathodes for high-brightness beams / C.H. Boulware ... [et al.]. Non linear evolution of short pulses in FEL cascaded undulators and the FEL harmonic cascade / L. Giannessi and P. Musumeci. High brightness laser induced multi-meV electron/proton sources / D. Giulietti ... [et al.]. Emittance limitation of a conditioned beam in a strong focusing FEL undulator / Z. Huang, G. Stupakov and S. Reiche. Scaled models: space-charge dominated electron storage rings / R.A. Kishek ... [et al.]. High brightness beam applications: energy recovered linacs / G.A. Krafft. Maximizing brightness in photoinjectors / C. Limborg-Deprey and H. Tomizawa. Ultracold electron sources / O.J. Luiten ... [et al.]. Scaling laws of structure-based optical accelerators / A. Mizrahi, V. Karagodsky and L. Schächter. High brightness beams-applications to free-electron lasers / S. Reiche. Conception of photo-injectors for the CTF3 experiment / R. Roux. Superconducting RF photoinjectors: an overview / J. Sekutowicz. Status and perspectives of photo injector developments for high brightness beams / F. Stephan. Results from the UCLA/FNLP underdense plasma lens experiment / M.C. Thompson ... [et al.]. Medical application of multi-beam compton scattering monochromatic tunable hard X-ray source / M. Uesaka ... [et al.]. Design of a 2 kA, 30 fs RF-photoinjector for waterbag compression / S.B. Van Der Geer, O.J. Luiten and M.J. De Loos. Proposal for a high-brightness pulsed electron source / M. Zolotorev ... [et al.]. -- Working Group 1. Summary of working group 1 on electron sources / M. Ferrario and G. Gatti. Design and RF measurements of an X-band accelerating structure for the SPARC project / D. Alesini ... [et al.]. Mitigation of RF gun breakdown by removal of tuning rods in high field regions / A.M. Cook... [et al.]. Measurements of quantum efficiency of Mg films produced by pulsed laser ablation deposition for application to bright electron sources / G. Gatti ... [et al.]. The S-band 1.6 cell RF gun correlated energy spread dependence on Pi and 0 mode relative amplitude / F. Schmerge ... [et al.]. RF gun photo-emission model for metal cathodes including time dependent emission / J.F. Schmerge ... [et al.]. Superconducting photocathodes / J. Smedley ... [et al.]. -- Working Group 2. Summary of Working Group 2: diagnostics and beam manipulation / G. Travish. Observation of coherent edge radiation emitted by a 100 Femtosecond compressed electron beam / G. Andonian, M, Dunning, E. Hemsing, J. B. Rosenzweig ... [et al.]. PARMELA simulations for PITZ: first machine studies and interpretation of measurements / M. Boscolo ... [et al.]. The LCLS single-shot relative bunch length monitor system / M.P. Dunning ... [et al.]. Beam shaping and permanent magnet quadrupole focusing with applications to the plasma wakefield accelerator / R.J. England ... [et al.]. Commissioning of the SPARC movable emittance meter and its first operation at PITZ / D. Filippetto... [et al.]. Experimental testing of dynamically optimized photoelectron beams / J.B. Rosenzweig ... [et al.]. Synchronization between the laser and electron beam in a photocathode RF gun / A. Sakumi ... [et al.]. Method of bunch radiation photochronography with 10 Femtosecond and less resolution / A. Tron and I. Merinov -- Working Group 3. New challenges in theory and modeling-summary for working group 3. L. Giannessi. Resonant modes in a 1.6 cells RF gun / M. Ferrario and C. Ronsivalle. Emittance degradation due to wake fields in a high brightness photoinjector / M. Ferrario, V. Fusco, M. Migliorati and L. Palumbo. Simulations of coherent synchroton radiation effects in electron machines / M. Migliorati, A, Schiavi and G. Dattoli. QFEL: A numerical code for multi-dimensional simulation of free electron lasers in the quantum regime / A. Schiavi ... [et al.]. First simulations results on laser pulse jitter and microbunching instability at Saprxino / M. Boscolo ... [et al.]. -- Working Group 4. Working group 4 summary: applications of high brightness beams to advanced accelerators and light sources / M. Uesaka and A. Rossi. Study of transverse effects in the production of X-rays with free-electron laser based on an optical ondulator / A. Bacci ... [et al.]. Channeling projects at LNF: from crystal undulators to capillary waveguides / S.B. Dabagov ... [et al.]. Mono-Energetic electron generation and plasma diagnosis experiments in a laser plasma cathode / K. Kinoshita ... [et al.]. A high-density electron beam and quad-scan measurements at Pleiades Thompson X-ray source / J.K. Lim ... [et al.]. Laser pulse circulation system for compact monochromatic tunable hard X-ray source / H. Ogino ... [et al.]. Limits on production of narrow band photons from inverse compton scattering / J. Rosenzweig and O. Williams. Preliminary results from the UCLA/SLAC ultra-high gradient Cerenkov wakefield accelerator experiment / M.C. Thompson ... [et al.]. Status of the polarized nonlinear inverse compton scattering experiment at UCLA / O. Williams... [et al.]. Coupling laser power into a slab-symmetric accelerator structure / R.B. Yoder and J.B. Rosenzweig.

Enhanced thermaly managed packaging for III-nitride light emitters

NASA Astrophysics Data System (ADS)

Kudsieh, Nicolas

In this Dissertation our work on `enhanced thermally managed packaging of high power semiconductor light sources for solid state lighting (SSL)' is presented. The motivation of this research and development is to design thermally high stable cost-efficient packaging of single and multi-chip arrays of III-nitrides wide bandgap semiconductor light sources through mathematical modeling and simulations. Major issues linked with this technology are device overheating which causes serious degradation in their illumination intensity and decrease in the lifetime. In the introduction the basics of III-nitrides WBG semiconductor light emitters are presented along with necessary thermal management of high power cingulated and multi-chip LEDs and laser diodes. This work starts at chip level followed by its extension to fully packaged lighting modules and devices. Different III-nitride structures of multi-quantum well InGaN/GaN and AlGaN/GaN based LEDs and LDs were analyzed using advanced modeling and simulation for different packaging designs and high thermal conductivity materials. Study started with basic surface mounted devices using conventional packaging strategies and was concluded with the latest thermal management of chip-on-plate (COP) method. Newly discovered high thermal conductivity materials have also been incorporated for this work. Our study also presents the new approach of 2D heat spreaders using such materials for SSL and micro LED array packaging. Most of the work has been presented in international conferences proceedings and peer review journals. Some of the latest work has also been submitted to well reputed international journals which are currently been reviewed for publication. .

HIGHLY VARIABLE YOUNG MASSIVE STARS IN ATLASGAL CLUMPS

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

Kumar, M. S. N.; Contreras Peña, C.; Lucas, P. W.

High-amplitude variability in young stellar objects (YSOs) is usually associated with episodic accretion events. It has not been observed so far in massive YSOs. Here, the high-amplitude variable star sample of Contreras Peña et al. has been used to search for highly variable (Δ K  ≥ 1 mag) sources coinciding with dense clumps mapped using the 850  μ m continuum emission by the ATLASGAL survey. A total of 18 variable sources are centered on the submillimeter clump peaks and coincide (<1″) with a 24  μ m point or compact (<10″) source. Of these 18 sources, 13 can be fit by YSOmore » models. The 13 variable YSOs (VYSOs) have luminosities of ∼10{sup 3} L {sub ⊙}, an average mass of 8  M {sub ⊙}, and a range of ages up to 10{sup 6} yr. A total of 11 of these 13 VYSOs are located in the midst of infrared dark clouds. Nine of the 13 sources have Δ K  > 2 mag, significantly higher compared to the mean variability of the entire VVV sample. The light curves of these objects sampled between 2010 and 2015 display rising, declining, or quasi-periodic behavior but no clear periodicity. Light-curve analysis using the Plavchan method shows that the most prominent phased signals have periods of a few hundred days. The nature and timescale of variations found in 6.7 Ghz methanol maser emission in massive stars are similar to that of the VYSO light curves. We argue that the origin of the observed variability is episodic accretion. We suggest that the timescale of a few hundred days may represent the frequency at which a spiraling disk feeds dense gas to the young massive star.« less

Multiple Paths to Mathematics Practice in Al-Kashi's Key to Arithmetic

NASA Astrophysics Data System (ADS)

Taani, Osama

2014-01-01

In this paper, I discuss one of the most distinguishing features of Jamshid al-Kashi's pedagogy from his Key to Arithmetic, a well-known Arabic mathematics textbook from the fifteenth century. This feature is the multiple paths that he includes to find a desired result. In the first section light is shed on al-Kashi's life and his contributions to mathematics and astronomy. Section 2 starts with a brief discussion of the contents and pedagogy of the Key to Arithmetic. Al-Kashi's multiple approaches are discussed through four different examples of his versatility in presenting a topic from multiple perspectives. These examples are multiple definitions, multiple algorithms, multiple formulas, and multiple methods for solving word problems. Section 3 is devoted to some benefits that can be gained by implementing al-Kashi's multiple paths approach in modern curricula. For this discussion, examples from two teaching modules taken from the Key to Arithmetic and implemented in Pre-Calculus and mathematics courses for preservice teachers are discussed. Also, the conclusions are supported by some aspects of these modules. This paper is an attempt to help mathematics educators explore more benefits from reading from original sources.

Joint SSRTNet/ALS-MES Workshop report

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

Shuh, David; Van Hove, Michel

2001-11-30

This joint workshop brought together experimentalists and theorists interested in synchrotron radiation and highlighted subjects relevant to molecular environmental science (MES). The strong mutual interest between the participants resulted in joint sessions on the first day, followed by more specialized parallel sessions on the second day. Held in conjunction with the Advanced Light Source (ALS) Users' Association Annual Meeting at the Lawrence Berkeley National Laboratory (Berkeley Lab), the Synchrotron Radiation Research Theory Network (SRRTNet) workshop was co-organized by Michel Van Hove (Berkeley Lab and University of California, Davis) and Andrew Canning (Berkeley Lab), while David Shuh (Berkeley Lab) organized themore » ALS-MES workshop. SRRTNet is a global network that promotes the interaction of theory and experiment (http://www.cse.clrc.ac.uk/Activity/SRRTnet). The ALS-MES project is constructing Beamline 11.0.2.1-2, a new soft x-ray beamline for MES investigations at photon energies from 75 eV to 2 keV, to provide photons for wet spectroscopy end stations and an upgraded scanning transmission x-ray microscope (STXM). The ALS-MES beamline and end stations will be available for users in the late fall of 2002.« less

Estimation of soft X-ray and EUV transition radiation power emitted from the MIRRORCLE-type tabletop synchrotron.

PubMed

Toyosugi, N; Yamada, H; Minkov, D; Morita, M; Yamaguchi, T; Imai, S

2007-03-01

The tabletop synchrotron light sources MIRRORCLE-6X and MIRRORCLE-20SX, operating at electron energies E(el) = 6 MeV and E(el) = 20 MeV, respectively, can emit powerful transition radiation (TR) in the extreme ultraviolet (EUV) and the soft X-ray regions. To clarify the applicability of these soft X-ray and EUV sources, the total TR power has been determined. A TR experiment was performed using a 385 nm-thick Al foil target in MIRRORCLE-6X. The angular distribution of the emitted power was measured using a detector assembly based on an NE102 scintillator, an optical bundle and a photomultiplier. The maximal measured total TR power for MIRRORCLE-6X is P(max) approximately equal 2.95 mW at full power operation. Introduction of an analytical expression for the lifetime of the electron beam allows calculation of the emitted TR power by a tabletop synchrotron light source. Using the above measurement result, and the theoretically determined ratio between the TR power for MIRRORCLE-6X and MIRRORCLE-20SX, the total TR power for MIRRORCLE-20SX can be obtained. The one-foil TR target thickness is optimized for the 20 MeV electron energy. P(max) approximately equal 810 mW for MIRRORCLE-20SX is obtained with a single foil of 240 nm-thick Be target. The emitted bremsstrahlung is negligible with respect to the emitted TR for optimized TR targets. From a theoretically known TR spectrum it is concluded that MIRRORCLE-20SX can emit 150 mW of photons with E > 500 eV, which makes it applicable as a source for performing X-ray lithography. The average wavelength, \\overline\\lambda = 13.6 nm, of the TR emission of MIRRORCLE-20SX, with a 200 nm Al target, could provide of the order of 1 W EUV.

Fosetyl-Al photo-Fenton degradation and its endogenous catalyst inhibition.

PubMed

Micó, María M; Zapata, Ana; Maldonado, Manuel I; Bacardit, Jordi; Malfeito, Jorge; Sans, Carme

2014-01-30

Interferences from many sources can affect photo-Fenton reaction performance. Among them, catalyst inhibition can be caused by the complexation and/or precipitation of iron species by the organic matter and salts present in the reaction media. This is the case of the oxidation of effluents containing organophosphorous fosetyl-Al. The degradation of this fungicide generates phosphate anions that scavenge iron and hinder Fe(II) availability. Experimental design was applied to artificially enlighten photo-Fenton reaction, in order to evaluate fosetyl-Al degradation. The performed experiments suggested how iron inhibition takes place. The monitoring of photo-Fenton reaction over a mixture of fosetyl-Al with other two pesticides also showed the interferences caused by the presence of the fungicide on other species degradation. Solar empowered photo-Fenton was also essayed for comparison purposes. Artificial and solar light photo-Fenton reactions were revealed as effective treatments for the elimination of tested fungicide. However, the phosphate ions generated during fosetyl oxidation decreased iron availability, what hampered organic matter degradation. Copyright © 2014 Elsevier B.V. All rights reserved.

234 nm and 246 nm AlN-Delta-GaN quantum well deep ultraviolet light-emitting diodes

NASA Astrophysics Data System (ADS)

Liu, Cheng; Ooi, Yu Kee; Islam, S. M.; Xing, Huili Grace; Jena, Debdeep; Zhang, Jing

2018-01-01

Deep ultraviolet (DUV) AlN-delta-GaN quantum well (QW) light-emitting diodes (LEDs) with emission wavelengths of 234 nm and 246 nm are proposed and demonstrated in this work. Our results reveal that the use of AlN-delta-GaN QW with ˜1-3 monolayer GaN delta-layer can achieve a large transverse electric (TE)-polarized spontaneous emission rate instead of transverse magnetic-polarized emission, contrary to what is observed in conventional AlGaN QW in the 230-250 nm wavelength regime. The switching of light polarization in the proposed AlN-delta-GaN QW active region is attributed to the rearrangement of the valence subbands near the Γ-point. The light radiation patterns obtained from angle-dependent electroluminescence measurements for the Molecular Beam Epitaxy (MBE)-grown 234 nm and 246 nm AlN-delta-GaN QW LEDs show that the photons are mainly emitted towards the surface rather than the edge, consistent with the simulated patterns achieved by the finite-difference time-domain modeling. The results demonstrate that the proposed AlN-delta-GaN QWs would potentially lead to high-efficiency TE-polarized surface-emitting DUV LEDs.

Infrared rotational light curves on Jupiter induced by wave activities and cloud patterns andimplications on brown dwarfs

NASA Astrophysics Data System (ADS)

Ge, Huazhi; Zhang, Xi; Fletcher, Leigh; Orton, Glenn S.; Sinclair, James Andrew; Fernandes,, Joshua; Momary, Thomas W.; Warren, Ari; Kasaba, Yasumasa; Sato, Takao M.; Fujiyoshi, Takuya

2017-10-01

Many brown dwarfs exhibit infrared rotational light curves with amplitude varying from a fewpercent to twenty percent (Artigau et al. 2009, ApJ, 701, 1534; Radigan et al. 2012, ApJ, 750,105). Recently, it was claimed that weather patterns, especially planetary-scale waves in thebelts and cloud spots, are responsible for the light curves and their evolutions on brown dwarfs(Apai et al. 2017, Science, 357, 683). Here we present a clear relationship between the direct IRemission maps and light curves of Jupiter at multiple wavelengths, which might be similar withthat on cold brown dwarfs. Based on infrared disk maps from Subaru/COMICS and VLT/VISIR,we constructed full maps of Jupiter and rotational light curves at different wavelengths in thethermal infrared. We discovered a strong relationship between the light curves and weatherpatterns on Jupiter. The light curves also exhibit strong multi-bands phase shifts and temporalvariations, similar to that detected on brown dwarfs. Together with the spectra fromTEXES/IRTF, our observations further provide detailed information of the spatial variations oftemperature, ammonia clouds and aerosols in the troposphere of Jupiter (Fletcher et al. 2016,Icarus, 2016 128) and their influences on the shapes of the light curves. We conclude that waveactivities in Jupiter’s belts (Fletcher et al. 2017, GRL, 44, 7140), cloud holes, and long-livedvortices such as the Great Red Spot and ovals control the shapes of IR light curves and multi-wavelength phase shifts on Jupiter. Our finding supports the hypothesis that observed lightcurves on brown dwarfs are induced by planetary-scale waves and cloud spots.

Peering Into an Early Galaxy

NASA Astrophysics Data System (ADS)

Kohler, Susanna

2018-04-01

Thirteen billion years ago, early galaxies ionized the gas around them, producing some of the first light that brought our universe out of its dark ages. Now the Atacama Large Millimeter/submillimeter Array (ALMA) has provided one of the first detailed looks into the interior of one of these early, distant galaxies.Sources of LightArtists illustration of the reionization of the universe (time progresses left to right), in which ionized bubbles that form around the first sources of light eventually overlap to form the fully ionized universe we observe today. [Avi Loeb/Scientific American]For the first roughly hundred million years of its existence, our universe expanded in relative darkness there were no sources of light at that time besides the cosmic microwave background. But as mass started to condense to form the first objects, these objects eventually shone as the earliest luminous sources, contributing to the reionization of the universe.To learn about the early production of light in the universe, our best bet is to study in detail the earliest luminous sources stars, galaxies, or quasars that we can hunt down. One ideal target is the galaxy COSMOS Redshift 7, known as CR7 for short.Targeting CR7CR7 is one of the oldest, most distant galaxies known, lying at a redshift of z 6.6. Its discovery in 2015 and subsequent observations of bright, ultraviolet-emitting clumps within it have led to broad speculation about the source of its emission. Does this galaxy host an active nucleus? Or could it perhaps contain the long-theorized first generation of stars, metal-free Population III stars?To determine the nature of CR7 and the other early galaxies that contributed to reionization, we need to explore their gas and dust in detail a daunting task for such distant sources! Conveniently, this is a challenge that is now made possible by ALMAs incredible capabilities. In a new publication led by Jorryt Matthee (Leiden University, the Netherlands), a team of scientists now reports on what weve learned peering into CR7s interior with ALMA.ALMA observations of [C II] (white contours) are overlaid on an ultraviolet image of the galaxy CR7 taken with Hubble (background image). The presence of [C II] throughout the galaxy indicate that CR7 does not primarily consist of metal-free gas, as had been previously proposed. [Matthee et al. 2017]Metals yet No Dust?Matthee and collaborators deep spectroscopic observations of CR7 targeted the far-infrared dust continuum emission and a gas emission line, [C II]. The authors detected [C II] emission in a large region in and around the galaxy, including near the ultraviolet clumps. This clearly indicates the presence of metals in these star-forming regions, and it rules out the possibility that CR7s gas is mostly primordial and forming metal-free Pop III stars.The authors do not detect far infrared continuum emission from dust, which sets an unusually low upper limit on the amount of dust that may be present in this galaxy. This limit allows them to better interpret their measurements of star formation rates in CR7, providing more information about the galaxys properties.Lastly, Matthee and collaborators note that the [C II] emission is detected in multiple different components that have different velocities. The authors propose that these components are accreting satellite galaxies. If this is correct, then CR7 is not only a target to learn about early sources of light in the universe its also a rare opportunity to directly witness the build-up of a central galaxy in the early universe.CitationJ. Matthee et al 2017 ApJ 851 145. doi:10.3847/1538-4357/aa9931

The use of aluminum nitride to improve Aluminum-26 Accelerator Mass Spectrometry measurements and production of Radioactive Ion Beams

NASA Astrophysics Data System (ADS)

Janzen, Meghan S.; Galindo-Uribarri, Alfredo; Liu, Yuan; Mills, Gerald D.; Romero-Romero, Elisa; Stracener, Daniel W.

2015-10-01

We present results and discuss the use of aluminum nitride as a promising source material for Accelerator Mass Spectrometry (AMS) and Radioactive Ion Beams (RIBs) science applications of 26Al isotopes. The measurement of 26Al in geological samples by AMS is typically conducted on Al2O3 targets. However, Al2O3 is not an ideal source material because it does not form a prolific beam of Al- required for measuring low-levels of 26Al. Multiple samples of aluminum oxide (Al2O3), aluminum nitride (AlN), mixed Al2O3-AlN as well as aluminum fluoride (AlF3) were tested and compared using the ion source test facility and the stable ion beam (SIB) injector platform at the 25-MV tandem electrostatic accelerator at Oak Ridge National Laboratory. Negative ion currents of atomic and molecular aluminum were examined for each source material. It was found that pure AlN targets produced substantially higher beam currents than the other materials and that there was some dependence on the exposure of AlN to air. The applicability of using AlN as a source material for geological samples was explored by preparing quartz samples as Al2O3 and converting them to AlN using a carbothermal reduction technique, which involved reducing the Al2O3 with graphite powder at 1600 °C within a nitrogen atmosphere. The quartz material was successfully converted to AlN. Thus far, AlN proves to be a promising source material and could lead towards increasing the sensitivity of low-level 26Al AMS measurements. The potential of using AlN as a source material for nuclear physics is also very promising by placing 26AlN directly into a source to produce more intense radioactive beams of 26Al.

The use of aluminum nitride to improve Aluminum-26 Accelerator Mass Spectrometry measurements and production of Radioactive Ion Beams

DOE PAGES

Janzen, Meghan S.; Galindo-Uribarri, Alfredo; Liu, Yuan; ...

2015-06-29

In this paper, we present results and discuss the use of aluminum nitride as a promising source material for Accelerator Mass Spectrometry (AMS) and Radioactive Ion Beams (RIBs) science applications of 26Al isotopes. The measurement of 26Al in geological samples by AMS is typically conducted on Al 2O 3 targets. However, Al 2O 3 is not an ideal source material because it does not form a prolific beam of Al - required for measuring low-levels of 26Al. Multiple samples of aluminum oxide (Al 2O 3), aluminum nitride (AlN), mixed Al 2O 3–AlN as well as aluminum fluoride (AlF 3) weremore » tested and compared using the ion source test facility and the stable ion beam (SIB) injector platform at the 25-MV tandem electrostatic accelerator at Oak Ridge National Laboratory. Negative ion currents of atomic and molecular aluminum were examined for each source material. It was found that pure AlN targets produced substantially higher beam currents than the other materials and that there was some dependence on the exposure of AlN to air. The applicability of using AlN as a source material for geological samples was explored by preparing quartz samples as Al 2O 3 and converting them to AlN using a carbothermal reduction technique, which involved reducing the Al 2O 3 with graphite powder at 1600°C within a nitrogen atmosphere. The quartz material was successfully converted to AlN. Thus far, AlN proves to be a promising source material and could lead towards increasing the sensitivity of low-level 26Al AMS measurements. In conclusion, the potential of using AlN as a source material for nuclear physics is also very promising by placing 26AlN directly into a source to produce more intense radioactive beams of 26Al.« less

Density and white light brightness in looplike coronal mass ejections - Temporal evolution

NASA Technical Reports Server (NTRS)

Steinolfson, R. S.; Hundhausen, A. J.

1988-01-01

Three ambient coronal models suitable for studies of time-dependent phenomena were used to investigate the propagation of coronal mass ejections initiated in each atmosphere by an identical energy source. These models included those of a static corona with a dipole magnetic field, developed by Dryer et al. (1979); a steady polytropic corona with an equatorial coronal streamer, developed by Steinolfson et al. (1982); and Steinolfson's (1988) model of heated corona with an equatorial coronal streamer. The results indicated that the first model does not adequately represent the general characteristics of observed looplike mass ejections, and the second model simulated only some of the observed features. Only the third model, which included a heating term and a streamer, was found to yield accurate simulation of the mess ejection observations.

Beam position monitor gate functionality implementation and applications

DOE PAGES

Cheng, Weixing; Ha, Kiman; Li, Yongjun; ...

2018-06-14

We introduce a novel technique to implement gate functionality for the beam position monitors (BPM) at the National Synchrotron Light Source II (NSLS-II). The functionality, now implemented in FPGA, allows us to acquire two separated bunch-trains’ synchronized turn-by-turn (TBT) data simultaneously with the NSLS-II in-house developed BPM system. The gated position resolution is improved about 3 times by narrowing the sampling width. Experimentally we demonstrated that the machine lattice could be transparently characterized with the gated TBT data of a short diagnostic bunch-train Cheng et al., 2017; Li et al., 2017. Other applications, for example, precisely characterizing storage ring impedance/wake-fieldmore » through recording the beam positions of two separated bunch trains has been experimentally demonstrated.« less

Comparative study of optical and scintillation properties of Tm3+:YAG, and Tm3+:LuAG single crystals

NASA Astrophysics Data System (ADS)

Fujimoto, Yutaka; Sugiyama, Makoto; Yanagida, Takayuki; Wakahara, Shingo; Suzuki, Shotaro; Kurosawa, Shunsuke; Chani, Valery; Yoshikawa, Akira

2013-09-01

The optical and scintillation properties of Tm3+-doped yttrium aluminum garnet Y3Al5O12 (YAG) and Tm3+-doped lutetium aluminum garnet Lu3Al5O12 (LuAG) are compared. The Tm3+-doped single crystals were grown by the micro-pulling down (μ-PD) technique. Both crystals demonstrated some emission peaks originated from 4f-4f forbidden transition of Tm3+ under 241Am alpha-ray excitation. The scintillation decay time of Tm3+-doped YAG was similar to that of LuAG. When irradiated by the gamma-rays from a 137Cs source, the relative scintillation light yields of Tm:YAG was 90% greater than that of Tm:LuAG.

Beam position monitor gate functionality implementation and applications

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

Cheng, Weixing; Ha, Kiman; Li, Yongjun

We introduce a novel technique to implement gate functionality for the beam position monitors (BPM) at the National Synchrotron Light Source II (NSLS-II). The functionality, now implemented in FPGA, allows us to acquire two separated bunch-trains’ synchronized turn-by-turn (TBT) data simultaneously with the NSLS-II in-house developed BPM system. The gated position resolution is improved about 3 times by narrowing the sampling width. Experimentally we demonstrated that the machine lattice could be transparently characterized with the gated TBT data of a short diagnostic bunch-train Cheng et al., 2017; Li et al., 2017. Other applications, for example, precisely characterizing storage ring impedance/wake-fieldmore » through recording the beam positions of two separated bunch trains has been experimentally demonstrated.« less

Sodium Inverse Relationships During Melting in Ultraslow Spreading Regions: Insights from SWIR-Smoothseafloor Peridotites

NASA Astrophysics Data System (ADS)

Cannat, M.; Brunelli, D.; Paquet, M.; Sforna, M. C.; Seyler, M.

2015-12-01

Ultraslow spreading ridges are key regions to unravel mantle processes. Low potential temperatures and reduced melting allow decrypting early melting processes and shad lights on the source short-scale heterogeneities and their interactions with transient melts. Mantle-derived peridotites from the Smoothseafloor region of the eastern Southwest Indian Ridge reveal countertrending Na-Ti relationships. Na apparently behaves as a compatible element during partial melting similarly to light REEs. Heavy REEs, however, follow a normal relationship with the other melting indicators (e.g. Cr#), a behaviour that results in pattern rotation around a pivot element when looking to REE systematic. These relationships can be explained by percolation of relatively enriched, grt-field derived, melts in the spinel-field melting mantle 1. A feature that also explains the inverse Na-Cr# correlation, frequently observed in abyssal mantle rocks. Experimental relationships constraint the grt-field derived melts to be produced by low-melting paragenesis that experience a garnet to spinel phase transition shallower than mantle peridotites for a given temperature. Based on potential mantle temperatures estimated by Cannat et al., 19992, the grt-sp transition can be set at ca. 2.0 and 1.5 GPa for mantle peridotites and Mg pyroxenites respectively with the onset of mantle melting at 1.2 GPa. Mass balance calculations based on the amount of produced melt constrains the pyroxenitic fraction < 10% by mass of the mantle source. The contemporaneous presence of lithologies too depleted with respect to the described process suggests that some portions of the mantle source are inherited from more sustained ancient depletion events not related to present-day processes beneath this ridge portion. PNRA funding : PdR 2013/B1.02 1. Brunelli, D., et al., 2104. Percolation of enriched melts during incremental open-system melting in the spinel field : A REE approach to abyssal peridotites from the Southwest Indian Ridge. Geochim. Cosmochim. Acta 127,190-203. 2. Cannat, M., et al., 1999. Formation of the axial relief at the very slow spreading Southwest Indian Ridge (49° to 69°E). J. Geophys. Res. 104, 22825-22843.

OLED lighting devices having multi element light extraction and luminescence conversion layer

DOEpatents

Krummacher, Benjamin Claus; Antoniadis, Homer

2010-11-16

An apparatus such as a light source has a multi element light extraction and luminescence conversion layer disposed over a transparent layer of the light source and on the exterior of said light source. The multi-element light extraction and luminescence conversion layer includes a plurality of light extraction elements and a plurality of luminescence conversion elements. The light extraction elements diffuses the light from the light source while luminescence conversion elements absorbs a first spectrum of light from said light source and emits a second spectrum of light.

Simulation model of Al-Ti dissimilar laser welding-brazing and its experimental verification

NASA Astrophysics Data System (ADS)

Behúlová, M.; Babalová, E.; Nagy, M.

2017-02-01

Formation of dissimilar weld joints of light metals and alloys including Al-Ti joints is interesting mainly due to demands on the weight reduction and corrosion resistance of components and structures in automotive, aircraft, aeronautic and other industries. Joining of Al-Ti alloys represents quite difficult problem. Generally, the fusion welding of these materials can lead to the development of different metastable phases and formation of brittle intermetallic compounds. The paper deals with numerical simulation of the laser welding-brazing process of titanium Grade 2 and EN AW 5083 aluminum alloy sheets using the 5087 aluminum filler wire. Simulation model for welding-brazing of testing samples with the dimensions of 50 × 100 × 2 mm was developed in order to perform numerical experiments applying variable welding parameters and to design proper combination of these parameters for formation of sound Al-Ti welded-brazed joints. Thermal properties of welded materials in the dependence on temperature were computed using JMatPro software. The conical model of the heat source was exploited for description of the heat input to the weld due to the moving laser beam source. The sample cooling by convection and radiation to the surrounding air and shielding argon gas was taken into account. Developed simulation model was verified by comparison of obtained results of numerical simulation with the temperatures measured during real experiments of laser welding-brazing by the TruDisk 4002 disk laser.

KCAT, Xradia, ALS and APS Performance Summary

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

Waters, A; Martz, H; Brown, W

2004-09-30

At Lawrence Livermore National Laboratory (LLNL) particular emphasis is being placed on the nondestructive characterization (NDC) of components, subassemblies and assemblies of millimeter-size extent with micrometer-size features (mesoscale). These mesoscale objects include materials that vary widely in composition, density, geometry and embedded features. Characterizing these mesoscale objects is critical for corroborating the physics codes that underlie LLNL's Stockpile Stewardship mission. In this report we present results from our efforts to quantitatively characterize the performance of several x-ray systems in an effort to benchmark existing systems and to determine which systems may have the best potential for our mesoscale imaging needs.more » Several different x-ray digital radiography (DR) and computed tomography (CT) systems exist that may be applicable to our mesoscale object characterization requirements, including microfocus and synchrotron systems. The systems we have benchmarked include KCAT (LLNL developed) and Xradia {mu}XCT (Xradia, Inc., Concord, CA), both microfocus systems, and Beamline 1-ID at the Advance Photon Source (APS) and the Tomography Beamline at the Advanced Light Source (ALS), both synchrotron based systems. The ALS Tomography Beamline is a new installation, and the data presented and analyzed here is some of the first to be acquired at the facility. It is important to note that the ALS system had not yet been optimized at the time we acquired data. Results for each of these systems has been independently documented elsewhere. In this report we summarize and compare the characterization results for these systems.« less

Primitive Mantle Nitrogen Revealed by SIMS in 3.5 Ga Harzburgitic Diamonds

NASA Astrophysics Data System (ADS)

Westerlund, K.; Richardson, S. H.; Shirey, S. B.; Hauri, E. H.; Gurney, J. J.

2009-12-01

The advent of the ion microprobe (SIMS) some 30 years ago marked the start of an exciting new approach to subcontinental lithospheric mantle (SCLM) studies. In-situ SIMS analysis of trace element zoning in mantle minerals, in combination with TIMS analysis of mineral separates, has revolutionized our understanding of equilibrium/disequilibrium relationships on a variety of time and length scales. For example, octahedral diamonds isolate mineral inclusions from diffusive exchange at mantle temperatures on a Gyr time scale, as well as preserving host diamond isotopic signatures that have long been used as indicators of the sources of diamond-forming fluids. Nitrogen, the main trace element in diamond, behaves as a compatible element during diamond growth [1] and SIMS has proved essential to determining C and N isotopic compositions on the scale of inclusions and associated diamond growth zones [2]. A suite of harzburgitic sulfide inclusion bearing diamonds from the 53 Ma Panda kimberlite, NWT, Canada, provides an ideal opportunity to characterize the source of diamond fluids in the world’s oldest macrodiamonds [3]. This suite gave a sulfide Re-Os isochron age of 3.52 ± 0.17 Ga with a radiogenic initial Os isotope signature characteristic of subduction-related fluids. The first-order variation in C (δ13C = -9 to 0‰) and N (δ15N = -25 to -7‰) isotopic composition of the host diamonds has been mapped by SIMS profiling of diamond plates. Collectively, the specimens show the following features: (i) compositional zoning/discontinuities indicating discrete growth stages and multiple fluids, (ii) overall core-to-rim decrease in N concentration variably well correlated with C and N isotopic composition, suggesting both open and closed system fractionation during diamond growth, (iii) initial N concentration correlated with N isotopic composition for different stones suggesting mixing of an ambient, isotopically light N component (<-26‰) and a heavier N component (still <0‰) introduced by the diamond-forming fluids. Given that these fluids are most likely the same as those carrying the radiogenic initial Os identified in the sulfide inclusions and host harzburgites [3], the heavier N component is probably also subduction-related. The light N component is then proposed to be primitive N in Archean SCLM that was characteristically light and resembled that of enstatite chondrites (as previously suggested by Cartigny et al [4] for undated peridotitic diamonds from Fuxian, China). The large spread in N isotopic composition of harzburgitic diamonds resulting from the reaction of multiple diamond-forming fluids with the SCLM and fractionation during diamond growth, shows that the mantle is more heterogeneous than recently claimed [5]. [1] Stachel et al (2009) doi: 10.1016/j.lithos.2009.04.017. [2] Hauri et al (2002) Chem Geol 185, 149-163. [3] Westerlund et al (2006) CMP 152, 275-294. [4] Cartigny et al (1997) Terra Nova 9, 175-179. [5] Cartigny et al (2009) doi: 10.1016/j.lithos.2009.06.007.

Identification and spatial distribution of light-toned deposits enriched in Al-phyllosilicates on the plateaus around Valles Marineris, Mars

NASA Astrophysics Data System (ADS)

Le Deit, L.; Flahaut, J.; Quantin, C.; Allemand, P.

2009-12-01

The plateaus around Valles Marineris consist in series of mafic rocks suggested to be flood basalts (McEwen et al., 1998), lavas interbedded with sediments (Malin and Edgett, 2000), layered intrusive rocks (Williams et al., 2003), or lava flows dated from the Noachian to the late Hesperian epochs (Scott and Carr, 1978). Recent studies show the occurrence of light layered deposits of hundred meters thick cropping out on plateaus near Ius Chasma, Melas Chasma, Candor Chasma, Juventae Chasma and Ganges Chasma deposited during the Hesperian epoch by fluvio-lacustrine processes (Weitz et al., 2009), or by air-fall processes (Le Deit et al., 2009). These layered deposits are enriched in hydrated minerals including opaline silica (Milliken et al., 2008), hydroxylated ferric sulfates (Bishop et al., 2009), and possibly Al-rich phyllosilicates (Le Deit et al., 2009). We identified another type of formation corresponding to light-toned massive deposits cropping out around Valles Marineris. It appears that these light-toned deposits are associated to bright, rough, and highly cratered terrains, located beneath a dark and thin capping unit. Previous studies report the occurrence of phyllosilicates on few locations around Valles Marineris based on OMEGA data analyses (Gondet et al., 2007; Carter et al., 2009). The analysis of CRISM data show that the light-toned deposits are associated with spectra displaying absorption bands at 1.4 μm, 1.9 μm, and a narrow band at 2.2 μm. These spectral characteristics are consistent with the presence of Al-rich phyllosilicates such as montmorillonite, or illite in the light-toned deposits. They constitute dozens of outcrops located on the plateaus south and east of Coprates Chasma and Capri Chasma, and west of Ganges Chasma. All outcrops investigated so far are present over Noachian terrains mapped as the unit Npl2 by Scott and Tanaka (1986), and Witbeck et al. (1991). These light-toned deposits could result from in situ aqueous alteration of Noachian basaltic plateaus during or after the Noachian epoch. We also identified Fe/Mg-rich phyllosilicates that are commonly found in the southern highland Noachian terrains (Mustard et al., 2008). They are located in central peaks, rims and ejecta of impact craters on plateaus, suggesting excavation of old buried layers. The deposits located around Valles Marineris are characterized by a wide variety of hydrated minerals that registered the evolution of the environmental conditions from the Noachian to the late Hesperian epochs. Further investigations are ongoing to determine their global spatial distribution and their stratigraphical relationships in order to better constrain the geological and climatic history of the region of Valles Marineris.

Effects of Mg-doped AlN/AlGaN superlattices on properties of p-GaN contact layer and performance of deep ultraviolet light emitting diodes

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

Al tahtamouni, T. M., E-mail: talal@yu.edu.jo; Lin, J. Y.; Jiang, H. X.

2014-04-15

Mg-doped AlN/AlGaN superlattice (Mg-SL) and Mg-doped AlGaN epilayers have been investigated in the 284 nm deep ultraviolet (DUV) light emitting diodes (LEDs) as electron blocking layers. It was found that the use of Mg-SL improved the material quality of the p-GaN contact layer, as evidenced in the decreased density of surface pits and improved surface morphology and crystalline quality. The performance of the DUV LEDs fabricated using Mg-SL was significantly improved, as manifested by enhanced light intensity and output power, and reduced turn-on voltage. The improved performance is attributed to the enhanced blocking of electron overflow, and enhanced hole injection.

Pulsar searches of Fermi unassociated sources with the Effelsberg telescope

NASA Astrophysics Data System (ADS)

Barr, E. D.; Guillemot, L.; Champion, D. J.; Kramer, M.; Eatough, R. P.; Lee, K. J.; Verbiest, J. P. W.; Bassa, C. G.; Camilo, F.; Çelik, Ö.; Cognard, I.; Ferrara, E. C.; Freire, P. C. C.; Janssen, G. H.; Johnston, S.; Keith, M.; Lyne, A. G.; Michelson, P. F.; Parkinson, P. M. Saz; Ransom, S. M.; Ray, P. S.; Stappers, B. W.; Wood, K. S.

2013-02-01

Using the 100-m Effelsberg radio telescope operating at 1.36 GHz, we have performed a targeted radio pulsar survey of 289 unassociated γ-ray sources discovered by the Large Area Telescope (LAT) aboard the Fermi satellite and published in the 1FGL catalogue (Abdo et al. 2010a). This survey resulted in the discovery of millisecond pulsar J1745+1017, which resides in a short-period binary system with a low-mass companion, M_{c,{min}} ˜ 0.0137 M_{⊙}, indicative of `black widow' type systems. A 2-yr timing campaign has produced a refined radio ephemeris, accurate enough to allow for phase-folding of the LAT photons, resulting in the detection of a dual-peaked γ-ray light curve, proving that PSR J1745+1017 is the source responsible for the γ-ray emission seen in 1FGL J1745.5+1018 (2FGL J1745.6+1015; Nolan et al. 2012). We find the γ-ray spectrum of PSR J1745+1017 to be well modelled by an exponentially cut-off power law with cut-off energy 3.2 GeV and photon index 1.6. The observed sources are known to contain a further 10 newly discovered pulsars which were undetected in this survey. Our radio observations of these sources are discussed and in all cases limiting flux densities are calculated. The reasons behind the seemingly low yield of discoveries are also discussed.

Pulsar searches of Fermi unassociated sources with the Effelsberg telescope

DOE PAGES

Barr, E. D.; Guillemot, L.; Champion, D. J.; ...

2012-12-21

Using the 100-m Effelsberg radio telescope operating at 1.36 GHz, we have performed a targeted radio pulsar survey of 289 unassociated γ-ray sources discovered by the Large Area Telescope (LAT) aboard the Fermi satellite and published in the 1FGL catalogue (Abdo et al. 2010a). In addition, this survey resulted in the discovery of millisecond pulsar J1745+1017, which resides in a short-period binary system with a low-mass companion, M c,min~0.0137M⊙, indicative of ‘black widow’ type systems. A 2-yr timing campaign has produced a refined radio ephemeris, accurate enough to allow for phase-folding of the LAT photons, resulting in the detection ofmore » a dual-peaked γ-ray light curve, proving that PSR J1745+1017 is the source responsible for the γ-ray emission seen in 1FGL J1745.5+1018 (2FGL J1745.6+1015; Nolan et al. 2012). We find the γ-ray spectrum of PSR J1745+1017 to be well modelled by an exponentially cut-off power law with cut-off energy 3.2 GeV and photon index 1.6. The observed sources are known to contain a further 10 newly discovered pulsars which were undetected in this survey. Our radio observations of these sources are discussed and in all cases limiting flux densities are calculated. Lastly, the reasons behind the seemingly low yield of discoveries are also discussed.« less

Doping concentration effect on performance of single QW double-heterostructure InGaN/AlGaN light emitting diode

NASA Astrophysics Data System (ADS)

Halim, N. Syafira Abdul; Wahid, M. Halim A.; Hambali, N. Azura M. Ahmad; Rashid, Shanise; Shahimin, Mukhzeer M.

2017-11-01

Light emitting diode (LED) employed a numerous applications such as displaying information, communication, sensing, illumination and lighting. In this paper, InGaN/AlGaN based on one quantum well (1QW) light emitting diode (LED) is modeled and studied numerically by using COMSOL Multiphysics 5.1 version. We have selected In0.06Ga0.94N as the active layer with thickness 50nm sandwiched between 0.15μm thick layers of p and n-type Al0.15Ga0.85N of cladding layers. We investigated an effect of doping concentration on InGaN/AlGaN double heterostructure of light-emitting diode (LED). Thus, energy levels, carrier concentration, electron concentration and forward voltage (IV) are extracted from the simulation results. As the doping concentration is increasing, the performance of threshold voltage, Vth on one quantum well (1QW) is also increases from 2.8V to 3.1V.

Low-Cost, Robust, and Field Portable Smartphone Platform Photometric Sensor for Fluoride Level Detection in Drinking Water.

PubMed

Hussain, Iftak; Ahamad, Kamal Uddin; Nath, Pabitra

2017-01-03

Groundwater is the major source of drinking water for people living in rural areas of India. Pollutants such as fluoride in groundwater may be present in much higher concentration than the permissible limit. Fluoride does not give any visible coloration to water, and hence, no effort is made to remove or reduce the concentration of this chemical present in drinking water. This may lead to a serious health hazard for those people taking groundwater as their primary source of drinking water. Sophisticated laboratory grade tools such as ion selective electrodes (ISE) and portable spectrophotometers are commercially available for in-field detection of fluoride level in drinking water. However, such tools are generally expensive and require expertise to handle. In this paper, we demonstrate the working of a low cost, robust, and field portable smartphone platform fluoride sensor that can detect and analyze fluoride concentration level in drinking water. For development of the proposed sensor, we utilize the ambient light sensor (ALS) of the smartphone as light intensity detector and its LED flash light as an optical source. An android application "FSense" has been developed which can detect and analyze the fluoride concentration level in water samples. The custom developed application can be used for sharing of in-field sensing data from any remote location to the central water quality monitoring station. We envision that the proposed sensing technique could be useful for initiating a fluoride removal program undertaken by governmental and nongovernmental organizations here in India.

Photocathodes for High Repetition Rate Light Sources

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

Ben-Zvi, Ilan

2014-04-20

This proposal brought together teams at Brookhaven National Laboratory (BNL), Lawrence Berkeley National Laboratory (LBNL) and Stony Brook University (SBU) to study photocathodes for high repetition rate light sources such as Free Electron Lasers (FEL) and Energy Recovery Linacs (ERL). Below details the Principal Investigators and contact information. Each PI submits separately for a budget through his corresponding institute. The work done under this grant comprises a comprehensive program on critical aspects of the production of the electron beams needed for future user facilities. Our program pioneered in situ and in operando diagnostics for alkali antimonide growth. The focus ismore » on development of photocathodes for high repetition rate Free Electron Lasers (FELs) and Energy Recovery Linacs (ERLs), including testing SRF photoguns, both normal-­conducting and superconducting. Teams from BNL, LBNL and Stony Brook University (SBU) led this research, and coordinated their work over a range of topics. The work leveraged a robust infrastructure of existing facilities and the support was used for carrying out the research at these facilities. The program concentrated in three areas: a) Physics and chemistry of alkali-­antimonide cathodes (BNL – LBNL) b) Development and testing of a diamond amplifier for photocathodes (SBU -­ BNL) c) Tests of both cathodes in superconducting RF photoguns (SBU) and copper RF photoguns (LBNL) Our work made extensive use of synchrotron radiation materials science techniques, such as powder-­ and single-­crystal diffraction, x-­ray fluorescence, EXAFS and variable energy XPS. BNL and LBNL have many complementary facilities at the two light sources associated with these laboratories (NSLS and ALS, respectively); use of these will be a major thrust of our program and bring our understanding of these complex materials to a new level. In addition, CHESS at Cornell will be used to continue seamlessly throughout the NSLS dark period and new diffraction facilities at ALS will be utilized. We also will continue to make use of the excellent analytical facilities at the CNF (BNL) and the Molecular Foundry (LBNL), where we have access to state of the art UHV XPS, SPM, SEM and scanning Auger microscopy.« less

Device structure for OLED light device having multi element light extraction and luminescence conversion layer

DOEpatents

Antoniadis,; Homer, Krummacher [Mountain View, CA; Claus, Benjamin [Regensburg, DE

2008-01-22

An apparatus such as a light source has a multi-element light extraction and luminescence conversion layer disposed over a transparent layer of the light source and on the exterior of said light source. The multi-element light extraction and luminescence conversion layer includes a plurality of light extraction elements and a plurality of luminescence conversion elements. The light extraction elements diffuses the light from the light source while luminescence conversion elements absorbs a first spectrum of light from said light source and emits a second spectrum of light.

Scaling of the VASIMR thruster first stage operation

NASA Astrophysics Data System (ADS)

Molvig, Kim; Batishchev, Oleg

2002-11-01

An effective helicon plasma source [1,2] is used in the variable high specific impulse VASIMR plasma thruster [3]. Experimental prototypes - VX-3 and recently up-scaled VX-10 [4] configurations operate with hydrogen, deuterium and helium plasmas. A set of models [5-7] has been developed to study VASIMR light gases helicon discharge. Using zero-dimensional model incorporating energy and mass balance equations we study scaling of the plasma source efficiency with the increased mass flow rate, applied electrical power and dimensions of the quartz tube. We compare theoretical results with existing experimental data. [1] M.A.Lieberman, A.J.Lihtenberg, 'Principles of ..', Wiley, 1994; [2] F.F.Chen, Plas. Phys. Contr. Fus. 33, 339, 1991; [3] F.Chang-Diaz et al, Bull. APS 45 (7) 129, 2000; [4] J.Squire et al., Bull. APS 45 (7) 130, 2000; [5] O.Batishchev, K.Molvig, AIAA technical paper 2000-3754, 2001; [6] O.Batishchev, K.Molvig, IEPC-01-208 paper, 27th Int. Electrical Propulsion Conf., 2001; [7] O.Batishchev, K.Molvig, AIAA technical paper 2002-0347, 2002.

Stable and Flexible CuInS2/ZnS:Al-TiO2 Film for Solar-Light-Driven Photodegradation of Soil Fumigant.

PubMed

Yan, Lili; Li, Zhichun; Sun, Mingxing; Shen, Guoqing; Li, Liang

2016-08-10

Semiconductor quantum dots (QDs) are suitable light absorbers for photocatalysis because of their unique properties. However, QDs generally suffer from poor photochemical stability against air, limiting their applications in photocatalysis. In this study, a stable solar-light-driven QDs-containing photocatalytic film was developed to facilitate photocatalytic degradation of the soil fumigant 1,3-dichloropropene (1,3-D). Highly stable CuInS2/ZnS:Al core/shell QDs (CIS/ZnS:Al QDs) were synthesized by doping Al into the ZnS shell and controlling ZnS:Al shell thickness; the CIS/ZnS:Al QDs were subsequently combined with TiO2 to form a CIS/ZnS:Al-TiO2 photocatalyst. The optimized ZnS:Al shell thickness for 1,3-D photodegradation was approximately 1.3 nm, which guaranteed and balanced the good photocatalytic activity and stability of the CIS/ZnS:Al-TiO2 photocatalyst. The photodegradation efficiency of 1,3-D can be maintained up to more than 80% after five cycles during recycling experiment. When CIS/ZnS:Al-TiO2 was deposited as photocatalytic film on a flexible polyethylene terephthalate substrate, over 99% of cis-1,3-D and 98% of trans-1,3-D were depleted as they passed through the film during 15 h of irradiation under natural solar light. This study demonstrated that the stable CIS/ZnS:Al-TiO2 photocatalyst both in powder and film form is a promising agent for photodegradation and emission reduction of soil fumigants.

Synthesis and optical properties of metal (M) atom-doped polycarbosilane (PCS) with extended conjugation (M = Al, Dy, Er and Eu)

NASA Astrophysics Data System (ADS)

Yao, Rongqian; Zhao, Haoran; Feng, Zude; Chen, Lifu; Zhang, Ying

2013-10-01

Optical properties of metal atom-doped polycarbosilane (PCS) which originated from σ-conjugation effect were studied. Al, Dy, Er and Eu were introduced into PCS by one-pot method to yield polyaluminocarbosilane (PACS), polydysprosiumcarbosilane (PDCS), polyerbiumcarbosilane (PErCS) and polyeuropiumcarbosilane (PECS), respectively. Effects of oxidation curing and ultraviolet (UV) radiation on the photoluminescence (PL) properties of the samples were investigated. PL spectra show strong blue light-emissions and the intensity of PCS is enhanced by adding metal atoms. PACS with extended σ-conjugation exhibits an obvious PL red-shift, high intensity, high quantum yield and excellent oxidation resistance as compared with those of others. As treated under UV lamp for 3 h in air, PACS retains good UV resistance performance, owing to the AlOx (x = 4, 5, or 6) groups which effectively extend the σ-conjugation. The obtained results are expected to have important applications in active sources for electroluminescence (EL) devices, especially suitable for blue emission.

Mo1-xWxSe2-Based Schottky Junction Photovoltaic Cells.

PubMed

Yi, Sum-Gyun; Kim, Sung Hyun; Park, Sungjin; Oh, Donggun; Choi, Hwan Young; Lee, Nara; Choi, Young Jai; Yoo, Kyung-Hwa

2016-12-14

We developed Schottky junction photovoltaic cells based on multilayer Mo 1-x W x Se 2 with x = 0, 0.5, and 1. To generate built-in potentials, Pd and Al were used as the source and drain electrodes in a lateral structure, and Pd and graphene were used as the bottom and top electrodes in a vertical structure. These devices exhibited gate-tunable diode-like current rectification and photovoltaic responses. Mo 0.5 W 0.5 Se 2 Schottky diodes with Pd and Al electrodes exhibited higher photovoltaic efficiency than MoSe 2 and WSe 2 devices with Pd and Al electrodes, likely because of the greater adjusted band alignment in Mo 0.5 W 0.5 Se 2 devices. Furthermore, we showed that Mo 0.5 W 0.5 Se 2 -based vertical Schottky diodes yield a power conversion efficiency of ∼16% under 532 nm light and ∼13% under a standard air mass 1.5 spectrum, demonstrating their remarkable potential for photovoltaic applications.

High precision AlGaAsSb ridge-waveguide etching by in situ reflectance monitored ICP-RIE

NASA Astrophysics Data System (ADS)

Tran, N. T.; Breivik, Magnus; Patra, S. K.; Fimland, Bjørn-Ove

2014-05-01

GaSb-based semiconductor diode lasers are promising candidates for light sources working in the mid-infrared wavelength region of 2-5 μm. Using edge emitting lasers with ridge-waveguide structure, light emission with good beam quality can be achieved. Fabrication of the ridge waveguide requires precise etch stop control for optimal laser performance. Simulation results are presented that show the effect of increased confinement in the waveguide when the etch depth is well-defined. In situ reflectance monitoring with a 675 nm-wavelength laser was used to determine the etch stop with high accuracy. Based on the simulations of laser reflectance from a proposed sample, the etching process can be controlled to provide an endpoint depth precision within +/- 10 nm.

Centaurus A, the core of the problem

NASA Technical Reports Server (NTRS)

Tingay, S. J.; Jauncey, D. L.; Preston, R. A.; Reynolds, J. E.; Meier, D. L.; Tzioumis, A. K.; Jones, D. L.; King, E. A.; Amy, S. W.; Biggs, J. D.

1994-01-01

The bright, peculiar elliptical galaxy Centaurus A (NGC 5128, PKS 1322-427) was one of the first extragalactic radio sources to be optically identified (Bolton et al. 1949). At a distance of 4 Mpc, Centaurus A is the closest active radio galaxy and affords the highest linear imaging resolution (1 mas approximately equal to 0.02 pc) and hence the best prospects for studying an active nucleus close to the central radio source. We present the results of multi-epoch, 8.4-GHz, very long baseline interferometry (VLBI), imaging observations of the nucleus made over the past three years. The nucleus possesses a core-jet structure where the inner portion of the jet shows apparent linear motion with a velocity substantially less than the speed of light.

Enhanced light extraction efficiency of micro-ring array AlGaN deep ultraviolet light-emitting diodes

NASA Astrophysics Data System (ADS)

Bekele Fayisa, Gabisa; Lee, Jong Won; Kim, Jungsub; Kim, Yong-Il; Park, Youngsoo; Kim, Jong Kyu

2017-09-01

An effective approach to overcome inherently poor light extraction efficiency of AlGaN-based deep ultraviolet (DUV) light-emitting diodes (LEDs) is presented. We demonstrated the 5 × 5 array micro-ring DUV LED having an inclined sidewall at the outer perimeter and a p-GaN-removed inner circle of the micro-ring, together with MgF2/Al omnidirectional reflectors. The micro-ring array DUV LED shows remarkably higher light output power by 70% than the reference, consistent with the calculated result, as well as comparable turn-on and operational voltages, which are attributed to the effective extraction of strong transverse-magnetic polarized anisotropic emission and the reduction of the absorption loss by the p-GaN contact layer, simultaneously.

Doubling The Intensity Of An ERL Based Light Source

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

Andrew Hutton

2005-05-01

A light source based on an Energy Recovered Linac (ERL) [1] consists of a superconducting linac and a transfer line that includes wigglers and undulators to produce the synchrotron light. The transfer line brings the electron bunches back to the beginning of the linac so that their energy can be recovered when they traverse the linac a second time, {lambda}/2 out of RF phase. There is another interesting condition when the length of the transfer line is (n {+-} 1/4) {lambda}. In this case, the electrons drift through on the zero RF crossing, and make a further pass around themore » transfer line, effectively doubling the circulating current in the wigglers and undulators. On the third pass through the linac, they will be decelerated and their energy recovered. The longitudinal focusing at the zero crossing is a problem, but it can be canceled if the drifting beam sees a positive energy gradient for the first half of the linac and a negative gradient for the second half (or vice versa). This paper presents a proposal to use a double chicane at the center of the linac to provide this focusing inversion for the drifting beam while leaving the accelerating and decelerating beams on crest. [1] G. R. Neil, et al, Phys. Rev. Let. 84, 662 2000« less

Large-Format AlGaN PIN Photodiode Arrays for UV Images

NASA Technical Reports Server (NTRS)

Aslam, Shahid; Franz, David

2010-01-01

A large-format hybridized AlGaN photodiode array with an adjustable bandwidth features stray-light control, ultralow dark-current noise to reduce cooling requirements, and much higher radiation tolerance than previous technologies. This technology reduces the size, mass, power, and cost of future ultraviolet (UV) detection instruments by using lightweight, low-voltage AlGaN detectors in a hybrid detector/multiplexer configuration. The solar-blind feature eliminates the need for additional visible light rejection and reduces the sensitivity of the system to stray light that can contaminate observations.

X-ray Characterization and Defect Control of III-Nitrides

NASA Astrophysics Data System (ADS)

Tweedie, James

A process for controlling point defects in a semiconductor using excess charge carriers was developed in theory and practice. A theoretical framework based on first principles was developed to model the effect of excess charge carriers on the formation energy and concentration of charged point defects in a semiconductor. The framework was validated for the completely general case of a generic carrier source and a generic point defect in a generic semiconductor, and then refined for the more specific case of a generic carrier source applied during the growth of a doped semiconductor crystal. It was theoretically demonstrated that the process as defined will always reduce the degree of compensation in the semiconductor. The established theoretical framework was applied to the case of above-bandgap illumination on both the MOCVD growth and the post-growth annealing of Mg-doped GaN thin films. It was theoretically demonstrated that UV light will lower the concentration of compensating defects during growth and will facilitate complete activation of the Mg acceptor at lower annealing temperatures. Annealing experiments demonstrated that UV illumination of GaN:Mg thin films during annealing lowers the resistivity of the film at any given temperature below the 650 °C threshold at which complete activation is achieved without illumination. Broad spectrum analysis of the photoluminescence (PL) spectra together with a correlation between the acceptor-bound exciton transition and room temperature resistivity demonstrated that UV light only acts to enhance the activation Mg. Surface chemistry and interface chemistry of AlN and high Al mole fraction AlGaN films were studied using x-ray photoelectron spectroscopy (XPS). It was seen that surfaces readily form stable surface oxides. The Schottky barrier height (SBH) of various metals contacted to these surfaces was using XPS. Finally, an x-ray diffraction method (XRD) was developed to quantify strain and composition of alloy films in the context of a processing environment. Reciprocal space mapping revealed intensity limitations on the accuracy of the method. The method was used to demonstrate a bimodal strain distribution across the composition spectrum for 200 nm AlGaN thin films grown on GaN. A weak, linear strain dependence on composition was observed for Al mole fractions below 30%. Above this threshold the films were observed to be completely relaxed by cracking.

Backscatter absorption gas imaging systems and light sources therefore

DOEpatents

Kulp, Thomas Jan [Livermore, CA; Kliner, Dahv A. V. [San Ramon, CA; Sommers, Ricky [Oakley, CA; Goers, Uta-Barbara [Campbell, NY; Armstrong, Karla M [Livermore, CA

2006-12-19

The location of gases that are not visible to the unaided human eye can be determined using tuned light sources that spectroscopically probe the gases and cameras that can provide images corresponding to the absorption of the gases. The present invention is a light source for a backscatter absorption gas imaging (BAGI) system, and a light source incorporating the light source, that can be used to remotely detect and produce images of "invisible" gases. The inventive light source has a light producing element, an optical amplifier, and an optical parametric oscillator to generate wavelength tunable light in the IR. By using a multi-mode light source and an amplifier that operates using 915 nm pump sources, the power consumption of the light source is reduced to a level that can be operated by batteries for long periods of time. In addition, the light source is tunable over the absorption bands of many hydrocarbons, making it useful for detecting hazardous gases.

Charged and Neutral Particles Channeling Phenomena Channeling 2008

NASA Astrophysics Data System (ADS)

Dabagov, Sultan B.; Palumbo, Luigi

2010-04-01

On the discovery of coherent Bremsstrahlung in a single crystal at the Frascati National Laboratories / C. Barbiellini, G. P. Murtas and S. B. Dabagov -- Advances in coherent Bremsstrahlung and LPM-effect studies (to the lOOth anniversary from the birth of L. D. Landau) / N. F. Shul'ga -- Spectra of radiation and created particles at intermediate energy in oriented crystal taking into account energy loss / V. N. Baier and V. M. Katkov -- The coherent Bremsstrahlung beam at MAX-lab facility / K. Fissum ... [et al.] -- Radiation from thin, structured targets (CERN NA63) / A. Dizdar -- Hard incoherent radiation in thick crystals / N. F. Shul'ga, V. V. Syshchenko and A. I. Tarnovsky -- Coherent Bremsstrahlung in periodically deformed crystals with a complex base / A. R. Mkrtchyan, A. A. Saharian and V. V. Parazian -- Induction of coherent x-ray Bremsstrahlung in crystals under the influence of acoustic waves / A. R. Mkrtchyan and V. V. Parazian -- Coherent processes in bent single crystals / V. A. Maisheev -- Experimental and theoretical investigation of complete transfer phenomenon for media with various heat exchange coefficients / A. R. Mkrtchyan, A. E. Movsisyan and V. R. Kocharyan -- Coherent pair production in crystals / A. R. Mkrtchyan, A. A. Saharian and V. V. Parazian -- Negative particle planar and axial channeling and channeling collimation / R. A. Carrigan, Jr. -- CERN crystal-based collimation in modern hadron colliders / W. Scandale -- Studies and application of bent crystals for beam steering at 70 GeV IHEP accelerator / A. G. Afonin ... [et al.] -- Crystal collimation studies at the Tevatron (T-980) / N. V. Mokhov ... [et al.] -- Fabrication of crystals for channeling of particles in accellerators / A. Mazzolari ... [et al.] -- New possibilities to facilitate collimation of both positively and negatively charged particle beams by crystals / V. Guidi, A. Mazzolari and V. V. Tikhomirov -- Increase of probability of particle capture into the channeling regime by a buried oxide layer / V. Guidi, A. Mazzolari and V. V. Tikhomirov -- A positron source using channeling in crystals for linear colliders / X. Artru ... [et al.] -- Parametric channeling and collapse of charged particles beams in crystals / M. Vysotskyy and V. Vysotskii.The formation and usage of coherent correlated charged particles states in the physics of channeling in crystals / S. V. Adamenko, V. I. Vysotskii and M. V. Vysotskyy -- Surface channeling of magnetic-charged particles on multilayer surface / S. V. Adamenko and V. I. Vysotskii -- Coherent creation of anti-hydrogen atoms in a crystal by relativistic antiproton / Yu. P. Kunashenko -- Thermal equilibrium of light ions in heavy crystals / E. Tsyganov -- Photon emission of electrons in a crystalline undulator / H. Backe ... [et al.] -- Channeling radiation from relativistic electrons in a crystal target as complementary x-ray and gamma ray source at synchrotron light facilities / K. B. Korotchenko, Yu. L. Pivovarov and T. A. Tukhfatullin -- Diffracted channeling radiation and other compound radiation processes / H. Nitta -- Collective scattering on the atom planes under the condition of full transition / A. R. Mkrtchyan ... [et al.] -- The proposal of the experiment on the research of the diffracted channeling radiation / D. A. Baklanov ... [et al.] -- Positron channeling at the DaOne BTF Facility: the cup experiment / L. Quintieri ... [et al.] -- Radiation spectra of 200 MeV electrons in diamond and silicon crystals at axial and planar orientations / K. Fissum ... [et al.] -- Channeling experiments with electrons at the Mainz Microtron Mami / W. Lauth ... [et al.] -- Dechanneling of positrons by dislocations: effects of anharmonic interactions / J. George and A. P. Pathak -- Diffracted channeling radiation from axially channeled relativistic electrons / K. B. Korotchenko ... [et al.] -- Intensive quasi-monochromatic, directed x-ray radiation of planar channeled positron bunch / L. Gevorgian -- Probing channeling radiation influenced by ultrasound / W. Wagner ... [et al.] -- Radiation characteristics under electrons planar channeling and quasichanneling in complex crystals / L. Gevorgian -- Formation of relativistic positron atoms by axially channeled positrons and their decay on [symbol]-rays / A. Gevorkyan, A. R. Mkrtchyan and K. Oganesyan -- New features of diffracted channeling radiation from electrons in Si and LiF Crystals / K. B. Korotchenko, Yu. L. Pivovarov and T. A. Tukhfatullin -- Modulated particle beam in a crystal channel / A. Kostyuk ... [et al.] -- Computer simulations of resonant coherent excitation of heavy hydrogenlike ions under planar channeling / A. A. Babaev and Yu. L. Pivovarov -- Parametric x-ray and diffracted transition radiation of 4.5 GeV electrons in diamond / R. O. Avakian ... [et al.] -- Possible use of small accelerators in student laboratory for engineering education / I. Endo, M. Tanaka and T. Yoshimura.The Status of the SPARC Project / A. Cianchi -- Laser-plasma acceleration: first experimental results from the Plasmon-X Project / L. A. Gizzi ... [et al.] -- The powerful nanosecond duration electron beam effect on the crystalline tungsten target / Y. N. Adischev ... [et al.] -- "Shadowing" of the electromagnetic field of a relativistic electron / G. Naumenko ... [et al.] -- The acceleration of the charged particles in a low temperature acoustoplasma / A. S. Abrahamyan, A. R. Mkrtchyan and R. B. Kostanyan -- The experimental study of the surface current excitation by a relativistic electron electromagnetic field / G. A. Naumenko ... [et al.] -- Synchrotron radiation from a charge moving along helical orbit around a dielectric cylinder / A. A. Saharian and A. S. Kotanjyan -- Particle acceleration in a helical wave guide / X. Artru and C. Ray -- Effect of heavy ion charge fluctuations on Cherenkov radiation / V. S. Malyshevsky -- Hard photons powerful radiation of electron bunch interacting with plasma beat waves / A. Shamamian and L. Gevorgian -- Diffraction radiation as a diagnostics tool at flash / M. Castellano, E. Chiadroni and A. Cianchi -- Methods of charged particle beam cooling / E. G. Bessonov -- Ray tracing calculation of PXR produced in curved and flat crystals by electron beams with large emittance / K. A. Ispirian ... [et al.] -- On dynamic effects in coherent x-radiation of relativistic electron in Bragg scattering geometry / S. V. Blazhevich and A. V. Noskov -- Optimization of relativistic electron diffracted transition radiation yield / S. V. Blazhevich and A. V. Noskov -- Geometrical effect of target crystal on PXR generation as a coherent x-ray source / Y. Hayakawa ... [et al.] -- Observation of dynamical maxima of parametric x-ray radiation for 20 Me V electron energy beam / A. R. Mkrtchyan ... [et al.] -- The comparison of monochromatic x-ray sources based on compact electron accelerators and x-ray tube / Yu. N. Adischev ... [et al.] -- Labsync: a project to develop a European facility based on a table-top synchrotron light source / G. Di Domenico ... [et al.] -- New experimental results with optical diffraction radiation diagnostics / E. Chiadroni ... [et al.] -- The radiation yield in different spectral ranges from low density structured laser plasma with different high Z-admixture / V. Rozanov and G. Vergunova -- Time and angular distributions of ions transmitted through insulating capillaries / F. F. Komarov and A. S. Kamyshan -- X-ray propagation in multiwall carbon nanotubes / P. A. Childs ... [et al.] -- Tunable x-ray source based on mosaic crystals using for medicine applications / D. A. Baklanov ... [et al.] -- Capillary optics based x-ray micro-imaging elemental analysis / D. Hampai ... [et al.] -- Neutron number enhancement in uranium thin film waveguides / S. P. Pogossian -- Schwinger scattering of fast neutrons in aligned crystal / Yu. P. Kunashenko and Yu. L. Pivovarov -- Experimental investigation of Smith-Purcell radiation focusing by using the parabolic gratings / G. A. Naumenko ... [et al.] -- Plasma channels in air produced by UV laser beam: mechanisms of photoionization and possible applications/ V. D. Zvorykin ... [et al.].

Tracing anthropogenic aerosol Fe sources in the North Atlantic Ocean using dissolved Fe isotope ratios

NASA Astrophysics Data System (ADS)

Conway, T. M.; Shelley, R.; Aguilar-Islas, A. M.; Landing, W. M.; Mahowald, N. M.; John, S.

2016-02-01

Supply of iron (Fe) to the surface ocean from atmospheric deposition plays a vital role in marine biogeochemical cycles, especially in Fe-limited areas or regions close to dust sources. However, large uncertainties remain over the fluxes, solubility and bioavailability of Fe supplied by aerosol dust. Additionally, aerosol Fe is likely to consist of a mixture of natural and anthropogenic (urban, biomass burning and combustion) components, which may have very different solubilities in seawater [e.g. 1]. To constrain soluble Fe supply to the oceans, it is thus vitally important to understand the relative contributions of different types of aerosol Fe, their solubilities and spatial distributions. Stable Fe isotopes (δ56Fe) may offer a way to discriminate between different dust sources [2], because of differential fractionation during a range of chemical processes. In this study, we measured δ56Fe in North Atlantic marine aerosols collected during two US GEOTRACES GA03 cruises (Lisbon to Woods Hole via Cape Verde, 2010-11) and we present δ56Fe measurements (relative to IRMM-014) from both the bulk aerosol (HF-HNO3 digested) and the water-soluble (10s ultrapure water leach) fractions. Aerosols collected from different air-masses (Saharan, European and N. American) allowed us to investigate the variability in δ56Fe due to different regional dust sources. The bulk phase was characterized by near-crustal δ56Fe values of +0.1±0.2‰, indicating the dominance of mineral dust. In contrast, the water-soluble fraction showed great variability; aerosols from European and North American air-masses were very isotopically light (-1.2±0.2‰ and -1.1±0.7‰) while those from Saharan air-masses were crustal (+0.1‰). Comparison of this data with isotope-informed model predictions of soluble Fe from mineral and anthropogenic sources (combustion, biofuels and biomass burning) [1], suggests that the data is consistent with mixing of either 1) Fe from mineral dust (+0.1‰) and a distinctly light anthropogenic Fe (-1.6‰), or 2) Fe from crustal mineral dust, isotopically heavy combustion Fe (+0.1 to +0.3‰), and biomass Fe that is both isotopically light (-1.6‰) and very soluble (>50%). [1] Luo, C. et al. (2008), Glob. Biogeochem. Cyc., 22, GB1012. [2] Mead, C. et al. (2013), Geophys. Res. Lett., 40, 5722-5727.

Sm-Nd isotopic systematics of the ancient Gneiss complex, southern Africa

NASA Technical Reports Server (NTRS)

Carlson, R. W.; Hunter, D. R.; Barker, F.

1983-01-01

In order to shed some new light on the question of the absolute and relative ages of the Ancient Gneiss Complex and Onverwacht Group, a Sm-Nd whole-rock and mineral isochron study of the AGC was begun. At this point, the whole-rock study of samples from the Bimodal Suite selected from those studied for their geochemical characteristics by Hunter et al., is completed. These results and their implications for the chronologic evolution of the Kaapvaal craton and the sources of these ancient rocks are discussed.

Experience with ActiveX control for simple channel access

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

Timossi, C.; Nishimura, H.; McDonald, J.

2003-05-15

Accelerator control system applications at Berkeley Lab's Advanced Light Source (ALS) are typically deployed on operator consoles running Microsoft Windows 2000 and utilize EPICS[2]channel access for data access. In an effort to accommodate the wide variety of Windows based development tools and developers with little experience in network programming, ActiveX controls have been deployed on the operator stations. Use of ActiveX controls for use in the accelerator control environment has been presented previously[1]. Here we report on some of our experiences with the use and development of these controls.

Driver circuit for solid state light sources

DOEpatents

Palmer, Fred; Denvir, Kerry; Allen, Steven

2016-02-16

A driver circuit for a light source including one or more solid state light sources, a luminaire including the same, and a method of so driving the solid state light sources are provided. The driver circuit includes a rectifier circuit that receives an alternating current (AC) input voltage and provides a rectified AC voltage. The driver circuit also includes a switching converter circuit coupled to the light source. The switching converter circuit provides a direct current (DC) output to the light source in response to the rectified AC voltage. The driver circuit also includes a mixing circuit, coupled to the light source, to switch current through at least one solid state light source of the light source in response to each of a plurality of consecutive half-waves of the rectified AC voltage.

Genome-wide association study of immunoglobulin light chain amyloidosis in three patient cohorts: comparison with myeloma.

PubMed

da Silva Filho, M I; Försti, A; Weinhold, N; Meziane, I; Campo, C; Huhn, S; Nickel, J; Hoffmann, P; Nöthen, M M; Jöckel, K-H; Landi, S; Mitchell, J S; Johnson, D; Morgan, G J; Houlston, R; Goldschmidt, H; Jauch, A; Milani, P; Merlini, G; Rowcieno, D; Hawkins, P; Hegenbart, U; Palladini, G; Wechalekar, A; Schönland, S O; Hemminki, K

2017-08-01

Immunoglobulin light chain (AL) amyloidosis is characterized by tissue deposition of amyloid fibers derived from immunoglobulin light chain. AL amyloidosis and multiple myeloma (MM) originate from monoclonal gammopathy of undetermined significance. We wanted to characterize germline susceptibility to AL amyloidosis using a genome-wide association study (GWAS) on 1229 AL amyloidosis patients from Germany, UK and Italy, and 7526 healthy local controls. For comparison with MM, recent GWAS data on 3790 cases were used. For AL amyloidosis, single nucleotide polymorphisms (SNPs) at 10 loci showed evidence of an association at P<10 -5 with homogeneity of results from the 3 sample sets; some of these were previously documented to influence MM risk, including the SNP at the IRF4 binding site. In AL amyloidosis, rs9344 at the splice site of cyclin D1, promoting translocation (11;14), reached the highest significance, P=7.80 × 10 -11 ; the SNP was only marginally significant in MM. SNP rs79419269 close to gene SMARCD3 involved in chromatin remodeling was also significant (P=5.2 × 10 -8 ). These data provide evidence for common genetic susceptibility to AL amyloidosis and MM. Cyclin D1 is a more prominent driver in AL amyloidosis than in MM, but the links to aggregation of light chains need to be demonstrated.

Development of high yielding photonic light delivery system for photodynamic therapy of esophageal carcinomas

NASA Astrophysics Data System (ADS)

Premasiri, Amaranath; Happawana, Gemunu; Rosen, Arye

2007-02-01

Photodynamic therapy (PDT) is an approved treatment modality for Barrett's and invasive esophageal carcinoma. Proper Combination of photosentizing agent, oxygen, and a specific wavelength of light to activate the photosentizing agents is necessary for the cytotoxic destruction of cancerous cells by PDT. As a light source expensive solid-state laser sources currently are being used for the treatment. Inexpensive semiconductor lasers have been suggested for the light delivery system, however packaging of semiconductor lasers for optimal optical power output is challenging. In this paper, we present a multidirectional direct water-cooling of semiconductor lasers that provides a better efficiency than the conventional unidirectional cooling. AlGaAsP lasers were tested under de-ionized (DI) water and it is shown that the optical power output of the lasers under the DI water is much higher than that of the uni-directional cooling of lasers. Also, in this paper we discuss how direct DI water-cooling can optimize power output of semiconductor lasers. Thereafter an optimal design of the semiconductor laser package is shown with the DI water-cooling system. Further, a microwave antenna is designed which is to be imprinted on to a balloon catheter in order to provide local heating of esophagus, leading to an increase in local oxygenation of the tumor to generate an effective level of singlet oxygen for cellular death. Finally the optimal level of light energy that is required to achieve the expected level of singlet oxygen is modeled to design an efficient PDT protocol.

ULX spectra revisited: Are accreting, highly magnetized neutron stars the engines of ultraluminous X-ray sources?

NASA Astrophysics Data System (ADS)

Koliopanos, F.; Vasilopoulos, G.; Bachetti, M.; Godet, O.; Webb, N.; Barret, D.

2017-10-01

In light of recent discoveries of pulsating ULXs and recently introduced models placing neutron stars as the central engines of ULXs, we revisit the spectra of seventeen ULXs, in search of indications that favor this hypothesis. To this end we examined the spectra from XMM-Newton observations of all seventeen sources in our sample. For six sources, these were complimented with spectra from public NuSTAR observations. We demonstrate that the notable ({>}6 keV) spectral curvature observed in most ULXs, is most likely due to thermal emission, with T{>} 1keV. More importantly, we find that a double thermal model (comprised of a 'cool' and 'hot' thermal component) - often associated with emission from neutron star X-ray binaries - describes all ULX spectra in our list. We propose that the dual thermal spectrum is the result of accretion onto highly magnetized NSs, as predicted in recent theoretical models (Mushtukov et al. 2017). We further argue that this finding offers an additional and compelling argument in favor of neutron stars as prime candidates for powering ULXs, as has been recently suggested (King & Lasota 2016; King et al. 2017). In my talk I will discuss the implications of our interpretation along with its merits and shortcomings.

COLLABORATIVE RESEARCH: Study of Aerosol Sources and Processing at the GVAX Pantnagar Supersite

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

Thornton, Joel A.; Worsnop, Douglas

2016-09-22

This project was part of a collaborative campaign, including the participation of scientists from seven research groups as part of the Winter Intensive Operating Period (January-February 2012) of the Clean Air for London (ClearfLo) campaign at a rural site in Detling, UK, 45 km southeast of central London to study wintertime sources of urban particulate matter. The UW contribution by PI Thornton’s group was to make the first deployment of a chemical ionization mass spectrometer instrument (MOVI-CI-ToFMS) to measure both particle and gas phase organic acids. The new instrument ran nearly continuously during the ClearfLo WINTER IOP at the Detlingmore » site, producing a first-ever data set of molecular composition information that can be used for source apportionment and process studies. The UW group published a paper in Environmental Science and Technology and contributed to another (Bohnenstengel et al BAMS 2015) detailing a direct molecular connection between biomass/biofuel burning particles and aerosol light absorption. The ES&T paper (Mohr, et al ES&T 2013) has received 42 citations in just 3 years indicative of its significant impact on the field. These measurements of urban and rural aerosol properties will contribute to improved modeling of regional aerosol emissions, and of atmospheric aging and removal.« less

Bright Eu2+-activated polycrystalline ceramic neutron scintillators

NASA Astrophysics Data System (ADS)

Wang, C. L.; Paranthaman, M. P.; Riedel, R. A.; Hodges, J. P.; Karlic, J. J.; Veatch, R. A.; Li, L.; Bridges, C. A.

2018-03-01

Scintillation properties of Eu2+-doped CaF2-AlF3-6LiF (Eu:CALF) polycrystalline ceramic thermal-neutron scintillators as a function of AlF3 concentration have been studied. The emission band peaked at a wavelength of 425-431 nm is due to the presence of Eu:CaF2 micro-crystallites. The highest light output from these samples is approximately 20,000 photons per thermal neutron, which is 3 times that of a GS20 6Li-glass scintillator. The pulse-decay lifetime and light output vs. AlF3 concentration may be understood using a radiation trapping model and the formation of a Li3AlF6 phase. At lower AlF3 concentration, Al3+ ions in Eu:CaF2 passivate the hole-trapping defects and enhance the light output; whereas at higher AlF3 concentration, Al3+ ions lead to the formation of electron trapping centers in Eu:CaF2 and the Li3AlF6 phase is formed, which reduces the light output. A neutron-gamma-discrimination (NGD) ratio of 9 × 108 was obtained from Principal Component Analysis (PCA) of digital waveforms, while Fisher Linear Discriminant Analysis (FLDA) can completely separate the thermal neutrons from 60Co gamma rays within the limit of gamma event statistics used in this work. Our results suggest that Eu:CALF scintillators can potentially replace the GS20 scintillator used for thermal and cold neutron detection systems.

Physical behaviour of anthropogenic light propagation into the nocturnal environment

PubMed Central

Aubé, Martin

2015-01-01

Propagation of artificial light at night (ALAN) in the environment is now known to have non negligible consequences on fauna, flora and human health. These consequences depend on light levels and their spectral power distributions, which in turn rely on the efficiency of various physical processes involved in the radiative transfer of this light into the atmosphere and its interactions with the built and natural environment. ALAN can affect the living organisms by direct lighting and indirect lighting (scattered by the sky and clouds and/or reflected by local surfaces). This paper mainly focuses on the behaviour of the indirect light scattered under clear sky conditions. Various interaction processes between anthropogenic light sources and the natural environment are discussed. This work mostly relies on a sensitivity analysis conducted with the light pollution radiative transfer model, Illumina (Aubé et al. 2005 Light pollution modelling and detection in a heterogeneous environment: toward a night-time aerosol optical depth retrieval method. In Proc. SPIE 2005, vol. 5890, San Diego, California, USA). More specifically, the impact of (i) the molecular and aerosol scattering and absorption, (ii) the second order of scattering, (iii) the topography and obstacle blocking, (iv) the ground reflectance and (v) the spectrum of light devices and their angular emission functions are examined. This analysis considers different behaviour as a function of the distance from the city centre, along with different zenith viewing angles in the principal plane. PMID:25780231

Physical behaviour of anthropogenic light propagation into the nocturnal environment.

PubMed

Aubé, Martin

2015-05-05

Propagation of artificial light at night (ALAN) in the environment is now known to have non negligible consequences on fauna, flora and human health. These consequences depend on light levels and their spectral power distributions, which in turn rely on the efficiency of various physical processes involved in the radiative transfer of this light into the atmosphere and its interactions with the built and natural environment. ALAN can affect the living organisms by direct lighting and indirect lighting (scattered by the sky and clouds and/or reflected by local surfaces). This paper mainly focuses on the behaviour of the indirect light scattered under clear sky conditions. Various interaction processes between anthropogenic light sources and the natural environment are discussed. This work mostly relies on a sensitivity analysis conducted with the light pollution radiative transfer model, Illumina (Aubé et al. 2005 Light pollution modelling and detection in a heterogeneous environment: toward a night-time aerosol optical depth retrieval method. In Proc. SPIE 2005, vol. 5890, San Diego, California, USA). More specifically, the impact of (i) the molecular and aerosol scattering and absorption, (ii) the second order of scattering, (iii) the topography and obstacle blocking, (iv) the ground reflectance and (v) the spectrum of light devices and their angular emission functions are examined. This analysis considers different behaviour as a function of the distance from the city centre, along with different zenith viewing angles in the principal plane. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

A study of effects of electrode contacts on performance of organic-based light-emitting field-effect transistors

NASA Astrophysics Data System (ADS)

Kim, Dae-Kyu; Choi, Jong-Ho

2018-02-01

Herein is presented a comparative performance analysis of heterojunction organic-based light-emitting field-effect transistors (OLEFETs) with symmetric (Au only) and asymmetric (Au and LiF/Al) electrode contacts. The devices had a top source-drain contact with long-channel geometry and were produced by sequentially depositing p-type pentacene and n-type N,N‧-ditridecylperylene-3,4,9,10-tetracarboxylic diimide (P13) using a neutral cluster beam deposition apparatus. The spectroscopic, structural and morphological properties of the organic thin films were examined using photoluminescence (PL) spectroscopy, X-ray diffraction (XRD) method, laser scanning confocal and atomic force microscopy (LSCM, AFM). Based upon the growth of high-quality, well-packed crystalline thin films, the devices demonstrated ambipolar field-effect characteristics, stress-free operational stability, and light emission under ambient conditions. Various device parameters were derived from the fits of the observed characteristics. The hole mobilities were nearly equal irrespective of the electrode contacts, whereas the electron mobilities of the transistors with LiF/Al drain electrodes were higher due to the low injection barrier. For the OLEFETs with symmetric electrodes, electroluminescence (EL) occurred only in the vicinity of the hole-injecting electrode, whereas for the OLEFETs with asymmetric electrodes, the emission occurred in the vicinity of both hole- and electron-injecting electrodes. By tuning the carrier injection and transport through high- and low-work function metals, the hole-electron recombination sites could be controlled. The operating conduction and light emission mechanism are discussed with the aid of EL images obtained using a charge-coupled device (CCD) camera.

AlGaN-based ultraviolet light-emitting diodes on sputter-deposited AlN templates with epitaxial AlN/AlGaN superlattices

NASA Astrophysics Data System (ADS)

Zhao, Lu; Zhang, Shuo; Zhang, Yun; Yan, Jianchang; Zhang, Lian; Ai, Yujie; Guo, Yanan; Ni, Ruxue; Wang, Junxi; Li, Jinmin

2018-01-01

We demonstrate AlGaN-based ultraviolet light-emitting diodes (UV-LEDs) grown by metalorganic chemical vapor deposition (MOCVD) on sputter-deposited AlN templates upon sapphire substrates. An AlN/AlGaN superlattices structure is inserted as a dislocation filter between the LED structure and the AlN template. The full width at half maximum values for (0002) and (10 1 bar 2) X-ray rocking curves of the n-type Al0.56Ga0.44N layer are 513 and 1205 arcsec, respectively, with the surface roughness of 0.52 nm. The electron concentration and mobility measured by Hall measurement are 9.3 × 1017cm-3 and 54 cm2/V·s at room temperature, respectively. The light output power of a 282-nm LED reaches 0.28 mW at 20 mA with an external quantum efficiency of 0.32%. And the values of leakage current and forward voltage of the LEDs are ∼3 nA at -10 V and 6.9 V at 20 mA, respectively, showing good electrical performance. It is expected that the cost of the UV-LED can be reduced by using sputter-deposited AlN template.

Position Index for the Matrix Light Source

NASA Astrophysics Data System (ADS)

Takahashi, Hiroshi; Kobayashi, Yoshinori; Onda, Shou; Irikura, Takashi

It is expected that in the future white LEDs will be widely used in practical applications including replacing conventional lighting in offices and homes. The white LED light source of matrix arrangement is also considered in it. On the other hand, although now the unified glare rating (UGR) is widely used for evaluation of the discomfort glare of the interior lighting, UGR is a thing for a uniform light source, and its application to the matrix light sources that have non-uniform luminance has not been considered. The aim of this study is to clarify the position index which is one of element of UGR for the matrix light source. In this case, to apply the position index for a matrix light source to UGR, the concept of the revised position index is invented. As the preliminary experiment, method for measuring the position index was conducted, and as the experiment, position index for the matrix light source was conducted and compared with the uniform light source. The results of the experiments show that the position index is decided by the relative angle between line of sight and light source. It is also found that the matrix light source have larger position index than uniform light source. Furthermore, it is shown that the discomfort glare caused by a matrix light source can be evaluated by applying the revised position index to the UGR.

Heavy Mg-doping of (Al,Ga)N films for potential applications in deep ultraviolet light-emitting structures

NASA Astrophysics Data System (ADS)

Liang, Y. H.; Towe, E.

2018-03-01

Doping of high aluminum-containing (Al,Ga)N thin films has remained a challenging problem that has hindered progress in the development of deep ultraviolet light-emitters. This paper reports on the synthesis and use of heavily doped (Al,Ga)N films in deep ultraviolet (˜274 nm) light-emitting structures; these structures were synthesized by molecular beam epitaxy under liquid-metal growth conditions that facilitate the incorporation of extremely high density of Mg dopant impurities (up to 5 × 1019 cm-3) into aluminum-rich (Al,Ga)N thin films. Prototypical light-emitting diode structures incorporating Al0.7Ga0.3N films doped with Mg impurities that ionize to give free hole carrier concentrations of up to 6 × 1017 cm-3 exhibit external quantum efficiencies of up 0.56%; this is an improvement from previous devices made from molecular beam epitaxy-grown materials. This improvement is believed to be due to the high hole carrier concentration enabled by the relatively low activation energy of 220 meV compared to the expected values of 408-507 meV for Al0.7Ga0.3N films.

Contributions of Ibn Al-Nafis (1210-1288 AD) to the progress of medicine and urology. A study and translations from his medical works.

PubMed

Abdel-Halim, Rabie E

2008-01-01

This primary-source study of 4 medical works of the 13th century Muslim scholar Ibn Al-Nafis confirmed that his Kitab Al-Mujaz Fi Al-Tibb was authored as an independent book meant to be a handbook for medical students and practitioners not as an epitome of Kitab Al-Qanun of Ibn Sina as thought by recent historians. His huge medical encyclopedia, Al-Shamil, represents a wave of intense scientific activity that spread among the scholars of Cairo and Damascus following the massive destruction of books by Hulako's Army during the devastation of Baghdad in 1258. Like his predecessors in the Islamic Era, Ibn Al-Nafis critically appraised the views of scholars before him in the light of his own experimentation and direct observations. Accordingly, in his books Sharh Tashreeh Al-Qanun, Risalat al-Aadaa and Al-Risalah Al-Kameleyyah, we find the first description of the coronary vessels and the true concept of the blood supply of the heart as well as the correct description of the pulmonary circulation and the beginnings of the proper understanding of the systemic circulation. Those discoveries of Ibn Al-Nafis, translated to Latin by Andreas Alpagus printed in Venice in 1547, appeared, 6 years later, in the Christianismi Restituto of Servetus and, in 1555, in the De Fabrica Humani Corporis of Vesalius 2nd edition then in the works of Valvarde 1554, Columbus 1559, Cesalpino 1571, and finally Harvey in 1628. Furthermore, this study documented several other contributions of Ibn Al-Nafis to the progress of human functional anatomy and to advances in medical and surgical practice.

Organic light-emitting diodes using novel embedded al gird transparent electrodes

NASA Astrophysics Data System (ADS)

Peng, Cuiyun; Chen, Changbo; Guo, Kunping; Tian, Zhenghao; Zhu, Wenqing; Xu, Tao; Wei, Bin

2017-03-01

This work demonstrates a novel transparent electrode using embedded Al grids fabricated by a simple and cost-effective approach using photolithography and wet etching. The optical and electrical properties of Al grids versus grid geometry have been systematically investigated, it was found that Al grids exhibited a low sheet resistance of 70 Ω □-1 and a light transmission of 69% at 550 nm with advantages in terms of processing conditions and material cost as well as potential to large scale fabrication. Indium Tin Oxide-free green organic light-emitting diodes (OLED) based on Al grids transparent electrodes was demonstrated, yielding a power efficiency >15 lm W-1 and current efficiency >39 cd A-1 at a brightness of 2396 cd m-2. Furthermore, a reduced efficiency roll-off and higher brightness have been achieved compared with ITO-base device.

Study of the Correlations and the MAXI Hardness Ratio between the Anomalous and Normal Low States of LMC X-3

NASA Astrophysics Data System (ADS)

Torpin, Trevor; Boyd, Patricia T.; Smale, Alan P.

2015-01-01

The bright, unusual black-hole X-ray binary LMC X-3 has been monitored virtually continuously by the Japanese MAXI X-ray All-Sky Monitor aboard the International Space Station (Matsuoka, et al., PASJ, 2009) from August 2009 to the present. Comparison with RXTE PCA and ASM light curves during the ~2.33-year period of overlap demonstrate that despite slight differences in energy-band boundaries both the ASM and MAXI faithfully reproduce characteristics of the high-amplitude, nonperiodic long-term variability, on the order of 100-300 days, clearly seen in the more sensitive PCA monitoring. The mechanism for this variability at a timescale many times longer than the 1.7-day orbital period is still unknown. Models to explain the long-term variability invoke mechanisms such as changes in mass transfer rate, and/or a precessing warped accretion disk. Observations of LMC X-3 have not definitely determined whether wind accretion or Roche-love overflow is the driver of the long-term variability. Recent MAXI monitoring of LMC X-3 includes excellent coverage of a rare anomalous low state (ALS) where the X-ray source cannot be distinguished from the background, as well as several normal low states, in which the source count rate passes smoothly through a low, yet detectable value. Pointed Swift XRT and UVOT observations also sample this ALS and one normal low state well. We combine these data sets to study the correlations between the wavelength regimes observed during the ALS versus the normal low. We also examine the behavior of the X-ray hardness ratios using XRT and MAXI monitoring data during the ALS versus the normal low state.

On the AlxGa1-xN/AlyGa1-yN/AlxGa1-xN (x>y) p-electron blocking layer to improve the hole injection for AlGaN based deep ultraviolet light-emitting diodes

NASA Astrophysics Data System (ADS)

Chu, Chunshuang; Tian, Kangkai; Fang, Mengqian; Zhang, Yonghui; Li, Luping; Bi, Wengang; Zhang, Zi-Hui

2018-01-01

This work proposes the [0001] oriented AlGaN-based deep ultraviolet (DUV) light-emitting diode (LED) possessing a specifically designed p-electron blocking layer (p-EBL) to achieve the high internal quantum efficiency. Both electrons and holes can be efficiently injected into the active region by adopting the Al0.60Ga0.40N/Al0.50Ga0.50N/Al0.60Ga0.40N structured p-EBL, in which a p-Al0.50Ga0.50N layer is embedded into the p-EBL. Moreover, the impact of different thicknesses for the p-Al0.50Ga0.50N insertion layer on the hole and electron injections has also been investigated. Compared with the DUV LED with the bulk p-Al0.60Ga0.40N as the EBL, the proposed LED architectures improve the light output power if the thickness of the p-Al0.50Ga0.50N insertion layer is properly designed.

Utility and safety of a novel surgical microscope laser light source

PubMed Central

Bakhit, Mudathir S.; Suzuki, Kyouichi; Sakuma, Jun; Fujii, Masazumi; Murakami, Yuta; Ito, Yuhei; Sugano, Tetsuo; Saito, Kiyoshi

2018-01-01

Objective Tissue injuries caused by the thermal effects of xenon light microscopes have previously been reported. Due to this, the development of a safe microscope light source became a necessity. A newly developed laser light source is evaluated regarding its effectiveness and safety as an alternative to conventional xenon light source. Methods We developed and tested a new laser light source for surgical microscopes. Four experiments were conducted to compare xenon and laser lights: 1) visual luminance comparison, 2) luminous and light chromaticity measurements, 3) examination and analysis of visual fatigue, and 4) comparison of focal temperature elevation due to light source illumination using porcine muscle samples. Results Results revealed that the laser light could be used at a lower illumination value than the xenon light (p < 0.01). There was no significant difference in visual fatigue status between the laser light and the xenon light. The laser light was superior to the xenon light regarding luminous intensity and color chromaticity. The focal temperature elevation of the muscle samples was significantly higher when irradiated with xenon light in vitro than with laser light (p < 0.01). Conclusion The newly developed laser light source is more efficient and safer than a conventional xenon light source. It lacks harmful ultraviolet waves, has a longer lifespan, a lower focal temperature than that of other light sources, a wide range of brightness and color production, and improved safety for the user’s vision. Further clinical trials are necessary to validate the impact of this new light source on the patient’s outcome and prognosis. PMID:29390016

High energy X-ray observations of CYG X-3 from from OSO-8: Further evidence of a 34.1 day period

NASA Technical Reports Server (NTRS)

Dolan, J. F.; Crannell, C. J.; Dennis, B. R.; Frost, K. J.; Orwig, L. E.

1981-01-01

The X-ray source Cyg X-3 (=4U2030+40) was observed with the high energy X-ray spectrometer on OSO-8 for two weeks in 1975 and in 1976 and for one week in 1977. No change in spectral shape and intensity above 23 keV was observed from year to year. No correlation is observed between the source's intensity and the phase of the 34.1 day period discovered by Molteni, et al. (1980). The pulsed fraction of the 4.8 hour light curve between 23 and 73 keV varies from week to week, however, and the magnitude of the pulsed fraction appears to be correlated with the 34.1 day phase. No immediate explanation of this behavior is apparent in terms of previously proposed models of the source.

The Fermi Large Area Telescope Thrid Gamma-ray Source Catalog

NASA Astrophysics Data System (ADS)

Stephens, Thomas E.; Ballet, Jean; Burnett, Toby; Cavazzuti, Elisabetta; Digel, Seth William; Fermi LAT Collaboration

2015-01-01

We present an overview of the third Fermi Large Area Telescope source catalog (3FGL) of sources in the 100 MeV - 300 GeV range. Based on the first four years of science data from the Fermi Gamma-ray Space Telescope mission, it is the deepest yet in this energy range. Relative to the 2FGL catalog (Nolan et al. 2012, ApJS 199, 31), the 3FGL catalog incorporates twice as much data as well as a number of analysis improvements, including improved calibrations at the event reconstruction level, an updated model for Galactic diffuse gamma-ray emission, a refined procedure for source detection, and improved methods for associating LAT sources with potential counterparts at other wavelengths. The 3FGL catalog includes 3033 sources, with source location regions, spectral properties, and monthly light curves for each. For approximately one-third of the sources we have not found counterparts at other wavelengths. More than 1100 of the identified or associated sources are active galaxies of the blazar class; several other classes of non-blazar active galaxies are also represented in the 3FGL. Pulsars represent the largest Galactic source class. From source counts of Galactic sources we estimate the contribution of unresolved sources to the Galactic diffuse emission.

Method of making AlInSb by metal-organic chemical vapor deposition

DOEpatents

Biefeld, Robert M.; Allerman, Andrew A.; Baucom, Kevin C.

2000-01-01

A method for producing aluminum-indium-antimony materials by metal-organic chemical vapor deposition (MOCVD). This invention provides a method of producing Al.sub.X In.sub.1-x Sb crystalline materials by MOCVD wherein an Al source material, an In source material and an Sb source material are supplied as a gas to a heated substrate in a chamber, said Al source material, In source material, and Sb source material decomposing at least partially below 525.degree. C. to produce Al.sub.x In.sub.1-x Sb crystalline materials wherein x is greater than 0.002 and less than one.

26Al Production in the Early Solar Nebula by Neutral High-Energy Plasma Winds

NASA Astrophysics Data System (ADS)

Spergel, M. S.

1995-09-01

In the light of recent observations, I believe that the sources for the presence of ^26Al within the solar nebula must be reconsidered [2,3]. Recent low observational estimates of the probability of encounters between mass-losing evolved stars and molecular clouds [4] for the production of ^26Al and the observed low production [5] of 26 Al from AGB (Asymptotic Giant Branch stars) along with the predicted low abundance of cosmic ray induced local production [6] in the early solar nebula all support continued investigation for additional sources of the solar nebula ^26Al presence. It is suggested based on the presences of new cross section data [7], that an important source of this ^26Al presence might be from enhanced interactions from the collisions of the local "T. Tauri" like plasma winds with the atomic and molecular Early Solar Nebula (ESN). Interactions like ^26Mg (p,n) ^26Al in this "neutral" electrical setting may provide the needed selective production. The ESN provides an environment where plasma winds can lead to such nucleosynthesis. Stellar winds of 300-700 km/s (about 3x10^7 K) are seen to T. Tauri like stars, presumed precursor to solar like stars, and also within the Solar heliosphere [8.9]. These winds provide the source of Solar High Energy Particles which can interact with such in situ targets such as ^26Mg to produce the ^26Al. The presence of the atomic and molecular environments, will enhance [10] nucleosynthesis over that seen in scattering of protons off bare nuclei. Such enhancement has been recently observed in low energy scattering on electrically shield targets [7]. There it was also suggested that in stellar convective zones, electron clouds of the plasma shield may also shield bare target nuclei. Measured values of low energy proton scattered on atomic and molecular targets indicated [7] that fusion cross sections are enlarged and elastic cross sections are reduced, therefore simple extrapolation of accelerator data can lead to an underestimate in the relevant excitation cross sections in lower energy proton induced production. Enhanced production in the ESN will be from the shielded atomic or molecular nuclei with the production increased by the product of this enhanced proton nucleosynthesis and the presence of the higher proton intensities for the lower energy particles available in the solar wind. References: [1] Supported under NIH-MARC grant #443789. [2] Clayton D. D. et al. (1977) Astrophys. J., 214, 300-315. [3] Clayton D. D. (1994) Nature, 368, 222-224. [4] Kastner J. H. and Myers P. C. (1994) Astrophys. J., 421, 605-614. [5] Prantzos N. (1993) Astrophys. J. Lett., 405, L55-L58. [6] Spergel M. S. (1995) Astrophys. Space Sci., 223, 187. [7] Castellani V. et al., The fate of Li and Be in stars and in the Laboratory, INFNFE-04-95 (preprint). [8] Simpson J. A. et al. (1995) Science, 268, 1019-1023. [9] Keppler E. et al. (1995) Science, 268, 1013-1016. [10] Rolfs C. E. and Rodney W. S. (1988) Cauldrons in the Cosmos (Nuclear Astrophysics), 165-168, Univ. of California.

High resolution x-ray Thomson scattering measurements from cryogenic hydrogen jets using the linac coherent light source

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

Fletcher, L. B., E-mail: lbfletch@slac.stanford.edu; Galtier, E.; Gamboa, E. J.

2016-11-15

We present the first spectrally resolved measurements of x-rays scattered from cryogenic hydrogen jets in the single photon counting limit. The 120 Hz capabilities of the LCLS, together with a novel hydrogen jet design [J. B. Kim et al., Rev. Sci. Instrum. (these proceedings)], allow for the ability to record a near background free spectrum. Such high-dynamic-range x-ray scattering measurements enable a platform to study ultra-fast, laser-driven, heating dynamics of hydrogen plasmas. This measurement has been achieved using two highly annealed pyrolytic graphite crystal spectrometers to spectrally resolve 5.5 keV x-rays elastically and inelastically scattered from cryogenic hydrogen and focusedmore » on Cornell-SLAC pixel array detectors [S. Herrmann et al., Nucl. Instrum. Methods Phys. Res., Sect. A 718, 550 (2013)].« less

Machine learning for micro-tomography

NASA Astrophysics Data System (ADS)

Parkinson, Dilworth Y.; Pelt, Daniël. M.; Perciano, Talita; Ushizima, Daniela; Krishnan, Harinarayan; Barnard, Harold S.; MacDowell, Alastair A.; Sethian, James

2017-09-01

Machine learning has revolutionized a number of fields, but many micro-tomography users have never used it for their work. The micro-tomography beamline at the Advanced Light Source (ALS), in collaboration with the Center for Applied Mathematics for Energy Research Applications (CAMERA) at Lawrence Berkeley National Laboratory, has now deployed a series of tools to automate data processing for ALS users using machine learning. This includes new reconstruction algorithms, feature extraction tools, and image classification and recommen- dation systems for scientific image. Some of these tools are either in automated pipelines that operate on data as it is collected or as stand-alone software. Others are deployed on computing resources at Berkeley Lab-from workstations to supercomputers-and made accessible to users through either scripting or easy-to-use graphical interfaces. This paper presents a progress report on this work.

Coupling Correction and Beam Dynamics at Ultralow Vertical Emittance in the ALS

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

Steier, Christoph; Robin, D.; Wolski, A.

2008-03-17

For synchrotron light sources and for damping rings of linear colliders it is important to be able to minimize the vertical emittance and to correct the spurious vertical dispersion. This allows one to maximize the brightness and/or the luminosity. A commonly used tool to measure the skew error distribution is the analysis of orbit response matrices using codes like LOCO. Using the new Matlab version of LOCO and 18 newly installed power supplies for individual skew quadrupoles at the ALS the emittance ratio could be reduced below 0.1% at 1.9 GeV yielding a vertical emittance of about 5 pm. Atmore » those very low emittances, additional effects like intra beam scattering become more important, potentially limiting the minimum emittance for machine like the damping rings of linear colliders.« less

AlN/ITO-Based Hybrid Electrodes with Conducting Filaments: Their Application to Ultraviolet Light-Emitting Diodes.

PubMed

Kim, Kyeong Heon; Lee, Tae Ho; Kim, Tae Geun

2017-07-19

A hybrid-type transparent conductive electrode (H-TCE) structure comprising an AlN rod array with conducting filaments (CFs) and indium tin oxide (ITO) films is proposed to improve both current injection and distribution as well as optical transmittance in the UV region. These CFs, generated in UV-transparent AlN rod areas using an electric field, can be used as conducting paths for carrier injection from a metal to a semiconductor such as p-(Al)GaN, which allows perfect Ohmic behavior with high transmittance (>95% at 365 nm) to be obtained. In addition, conduction across AlN rods and Ohmic conduction mechanisms are investigated by analyzing AlN rods and AlN rod/p-AlGaN film interfaces. We apply these H-TCEs to three near-UV light-emitting diodes (LEDs) (385 nm LEDs with p-GaN and p-AlGaN terminated surfaces and 365 nm LED with p-AlGaN terminated surface). We confirm that the light power outputs increase by 66%, 79%, and 103%, whereas the forward voltages reduce by 5.6%, 10.2%, and 8.6% for 385 nm p-GaN terminated, 385 nm p-AlGaN terminated, and 365 nm p-AlGaN terminated LEDs with H-TCEs, respectively, compared to LEDs with reference ITOs.

Method and apparatus for acquisition and tracking of light sources in a transient event rich environment

NASA Technical Reports Server (NTRS)

Bolin, Kenneth (Inventor); Flynn, David (Inventor); Fowski, Walter (Inventor); Miklus, Kenneth (Inventor); Kissh, Frank (Inventor); Abreu, Rene (Inventor)

1993-01-01

A method and apparatus for tracking a light source in a transient event rich environment locks on to a light source incident on a field-of-view 1 of a charge-coupled-device (CCD) array 6, validates the permanence of said light source and transmits data relating to the brilliance and location of said light source if said light source is determined to be permanent.

Effect of accelerated global expansion on the bending of light

NASA Astrophysics Data System (ADS)

Aghili, Mir Emad; Bolen, Brett; Bombelli, Luca

2017-01-01

In 2007 Rindler and Ishak showed that, contrary to previous claims, the value of the cosmological constant does have an effect on light deflection by a gravitating object in an expanding universe. In their work they considered a Schwarzschild-de Sitter (SdS) spacetime, which has a constant asymptotic expansion rate H_0. A model with a time-dependent H( t) was studied by Kantowski et al., who consider in their 2010 paper a "Swiss-cheese" model of a Friedmann-Lemaître-Robertson-Walker (FLRW) spacetime with an embedded SdS bubble. In this paper, we generalize the Rindler and Ishak model to time-varying H( t) in another way, by considering light bending in a McVittie metric representing a gravitating object in a FLRW cosmological background. We carry out numerical simulations of the propagation of null geodesics in different McVittie spacetimes, in which we keep the values of the distances from the observer to the lensing object and to the source fixed, and vary the form of H( t).

Non-contact pumping of light emitters via non-radiative energy transfer

DOEpatents

Klimov, Victor I.; Achermann, Marc

2010-01-05

A light emitting device is disclosed including a primary light source having a defined emission photon energy output, and, a light emitting material situated near to said primary light source, said light emitting material having an absorption onset equal to or less in photon energy than the emission photon energy output of the primary light source whereby non-radiative energy transfer from said primary light source to said light emitting material can occur yielding light emission from said light emitting material.

An integrated approach to assess heavy metal source apportionment in peri-urban agricultural soils.

PubMed

Huang, Ying; Li, Tingqiang; Wu, Chengxian; He, Zhenli; Japenga, Jan; Deng, Meihua; Yang, Xiaoe

2015-12-15

Three techniques (Isotope Ratio Analysis, GIS mapping, and Multivariate Statistical Analysis) were integrated to assess heavy metal pollution and source apportionment in peri-urban agricultural soils. The soils in the study area were moderately polluted with cadmium (Cd) and mercury (Hg), lightly polluted with lead (Pb), and chromium (Cr). GIS Mapping suggested Cd pollution originates from point sources, whereas Hg, Pb, Cr could be traced back to both point and non-point sources. Principal component analysis (PCA) indicated aluminum (Al), manganese (Mn), nickel (Ni) were mainly inherited from natural sources, while Hg, Pb, and Cd were associated with two different kinds of anthropogenic sources. Cluster analysis (CA) further identified fertilizers, waste water, industrial solid wastes, road dust, and atmospheric deposition as potential sources. Based on isotope ratio analysis (IRA) organic fertilizers and road dusts accounted for 74-100% and 0-24% of the total Hg input, while road dusts and solid wastes contributed for 0-80% and 19-100% of the Pb input. This study provides a reliable approach for heavy metal source apportionment in this particular peri-urban area, with a clear potential for future application in other regions. Copyright © 2015 Elsevier B.V. All rights reserved.

Image statistics and the perception of surface gloss and lightness.

PubMed

Kim, Juno; Anderson, Barton L

2010-07-01

Despite previous data demonstrating the critical importance of 3D surface geometry in the perception of gloss and lightness, I. Motoyoshi, S. Nishida, L. Sharan, and E. H. Adelson (2007) recently proposed that a simple image statistic--histogram or sub-band skew--is computed by the visual system to infer the gloss and albedo of surfaces. One key source of evidence used to support this claim was an experiment in which adaptation to skewed image statistics resulted in opponent aftereffects in observers' judgments of gloss and lightness. We report a series of adaptation experiments that were designed to assess the cause of these aftereffects. We replicated their original aftereffects in gloss but found no consistent aftereffect in lightness. We report that adaptation to zero-skew adaptors produced similar aftereffects as positively skewed adaptors, and that negatively skewed adaptors induced no reliable aftereffects. We further find that the adaptation effect observed with positively skewed adaptors is not robust to changes in mean luminance that diminish the intensity of the luminance extrema. Finally, we show that adaptation to positive skew reduces (rather than increases) the apparent lightness of light pigmentation on non-uniform albedo surfaces. These results challenge the view that the adaptation results reported by Motoyoshi et al. (2007) provide evidence that skew is explicitly computed by the visual system.

Thermoluminescence and optically stimulated luminescence disadvantages of α-Al2O3:C crystal grown by the temperature gradient technique

NASA Astrophysics Data System (ADS)

Yang, Xin-Bo; Xu, Jun; Li, Hong-Jun; Bi, Qun-Yu; Cheng, Yan; Su, Liang-Bi; Tang, Qiang

2010-04-01

Recently, α-Al2O3:C crystal with highly sensitive thermoluminescence (TL) and optically stimulated luminescence (OSL) has been successfully grown by the temperature gradient technique. This paper investigates the heating rate dependence of TL sensitivity, light-induced fading of TL signals and thermal stability of OSL of α-Al2O3:C crystals. As the heating rate increases, the integral TL response decreases and the dosimetric glow peak shifts to higher temperatures in α-Al2O3:C crystals. Light-induced fading of TL increases with the irradiation dose, and TL response decreases as the exposure time increases, especially in the first 15 minutes. With the increasing intensity of the exposure light, the TL fading of α-Al2O3:C crystal increases sharply. The OSL response of as-grown α-Al2O3:C crystal is quite stable below 373 K and decreases sharply for higher temperatures.

AlGaN-based deep ultraviolet light-emitting diodes grown on nano-patterned sapphire substrates with significant improvement in internal quantum efficiency

NASA Astrophysics Data System (ADS)

Dong, Peng; Yan, Jianchang; Zhang, Yun; Wang, Junxi; Zeng, Jianping; Geng, Chong; Cong, Peipei; Sun, Lili; Wei, Tongbo; Zhao, Lixia; Yan, Qingfeng; He, Chenguang; Qin, Zhixin; Li, Jinmin

2014-06-01

We report high-performance AlGaN-based deep ultraviolet light-emitting diodes grown on nano-patterned sapphire substrates (NPSS) using metal-organic chemical vapor deposition. By nanoscale epitaxial lateral overgrowth on NPSS, 4-μm AlN buffer layer has shown strain relaxation and a coalescence thickness of only 2.5 μm. The full widths at half-maximum of X-ray diffraction (002) and (102) ω-scan rocking curves of AlN on NPSS are only 69.4 and 319.1 arcsec. The threading dislocation density in AlGaN-based multi-quantum wells, which are grown on this AlN/NPSS template with a light-emitting wavelength at 283 nm at room temperature, is reduced by 33% compared with that on flat sapphire substrate indicated by atomic force microscopy measurements, and the internal quantum efficiency increases from 30% to 43% revealed by temperature-dependent photoluminescent measurement.

Silicon Isotope Geochemistry of Ocean Island Basalts: Search for Deep Mantle Heterogeneities and Evidence for Recycled Altered Oceanic Crust

NASA Astrophysics Data System (ADS)

Pringle, E. A.; Savage, P. S.; Jackson, M. G.; Moreira, M. A.; Day, J. M.; Moynier, F.

2014-12-01

Analyses of Ocean Island Basalts (OIB) have shown that the Earth's mantle contains isotopically distinct components, but debate about the degree and cause of variability persists. The study of silicon (Si) isotopes in OIBs has the potential to elucidate mantle heterogeneities. Relatively large (~several per mil) Si isotopic fractionation occurs in low-temperature environments during precipitation from dissolved Si, where the precipitate is preferentially enriched in the lighter isotopes [1], but only a limited range (~tenths of a per mil) of Si isotope fractionation has been observed due to high-temperature igneous processes [2]. Therefore, Si isotopes may be useful as tracers for the presence of crustal material in OIB source regions in a manner similar to more conventional stable isotope systems, such as oxygen. Here we present the first comprehensive suite of high-precision Si isotopic data obtained by MC-ICP-MS for a diverse set of OIBs representing the EM-1, EM-2, and HIMU mantle components. In general, the Si isotopic compositions of OIBs analyzed here are agreement with previous estimates for Bulk Silicate Earth (BSE). However, small systematic variations are present; the HIMU end-member Mangaia and HIMU-type Cape Verde island São Nicolau are enriched in the light isotopes of Si (δ30Si = -0.37 ± 0.06‰ and δ30Si = -0.39 ± 0.04‰, respectively; errors are 2sd), with compositions intermediary between Mid Ocean Ridge Basalts and chondritic values. Additionally, Iceland samples from volcanic complexes in the Northern Rift Zone show similar Si isotope compositions (on average, δ30Si = -0.40 ± 0.06‰). In contrast, the δ30Si averages of the EM-1 end-member Pitcairn (-0.28 ± 0.07‰), the EM-2 end-member Samoa (-0.31 ± 0.07‰) and other OIB localities do not show any significant difference from previous estimates for the δ30Si value of BSE [3]. The Si isotopic variability in some HIMU-type and Icelandic OIBs most likely reflects the incorporation of recycled altered oceanic crust in the plume source. However, the sampling of a primitive reservoir enriched in the light isotopes of Si, as suggested by [4], cannot be ruled out as a potential source of Si isotope variations in OIBs. References: [1] Ziegler et al., GCA 2005 [2] Savage et al., GCA 2011 [3] Savage et al., EPSL 2010 [4] Huang et al., GCA 2014

Improved performance of GaN based light emitting diodes with ex-situ sputtered AlN nucleation layers

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

Chen, Shuo-Wei; Epistar Corporation, Hsinchu 300, Taiwan; Li, Heng

The crystal quality, electrical and optical properties of GaN based light emitting diodes (LEDs) with ex-situ sputtered physical vapor deposition (PVD) aluminum nitride (AlN) nucleation layers were investigated. It was found that the crystal quality in terms of defect density and x-ray diffraction linewidth was greatly improved in comparison to LEDs with in-situ low temperature GaN nucleation layer. The light output power was 3.7% increased and the reverse bias voltage of leakage current was twice on LEDs with ex-situ PVD AlN nucleation layers. However, larger compressive strain was discovered in LEDs with ex-situ PVD AlN nucleation layers. The study showsmore » the potential and constrain in applying ex-situ PVD AlN nucleation layers to fabricate high quality GaN crystals in various optoelectronics.« less

Growth of Nd doped (Lu, Gd)3(Ga, Al)5O12 single crystal by the micro pulling down method and their scintillation properties

NASA Astrophysics Data System (ADS)

Kamada, Kei; Kurosawa, Shunsuke; Yamaji, Akihiro; Shoji, Yasuhiro; Pejchal, Jan; Ohashi, Yuji; Yokota, Yuui; Yoshikawa, Akira

2015-03-01

Nd 1 mol% doped (Lu, Gd)3(Ga, Al)5O12 (LGGAG) single crystals were grown by the micro-pulling down (μ-PD) method. Luminescence and scintillation properties such as absorption, excitation and emission spectra, light yield and decay time were evaluated. Nd1%:Lu3Al5O12 showed the highest light output of around 8200 photons/MeV among the grown crystals. Scintillation decay time of Nd:Y3Al5O12 was 1.32 μs (36%) 2.02 μs (64%). Nd:Lu3Ga3Al2O12 was relatively high dense scintillator of 7.38 g/cm3 with good light yield of 6800 photons/MeV and scintillation decay time of 0.20 μs (5%) 2.60 μs (95%).

Human amyloidogenic light chain proteins result in cardiac dysfunction, cell death, and early mortality in zebrafish.

PubMed

Mishra, Shikha; Guan, Jian; Plovie, Eva; Seldin, David C; Connors, Lawreen H; Merlini, Giampaolo; Falk, Rodney H; MacRae, Calum A; Liao, Ronglih

2013-07-01

Systemic amyloid light-chain (AL) amyloidosis is associated with rapidly progressive and fatal cardiomyopathy resulting from the direct cardiotoxic effects of circulating AL light chain (AL-LC) proteins and the indirect effects of AL fibril tissue infiltration. Cardiac amyloidosis is resistant to standard heart failure therapies, and, to date, there are limited treatment options for these patients. The mechanisms underlying the development of cardiac amyloidosis and AL-LC cardiotoxicity are largely unknown, and their study has been limited by the lack of a suitable in vivo model system. Here, we establish an in vivo zebrafish model of human AL-LC-induced cardiotoxicity. AL-LC isolated from AL cardiomyopathy patients or control nonamyloidogenic LC protein isolated from multiple myeloma patients (Con-LC) was directly injected into the circulation of zebrafish at 48 h postfertilization. AL-LC injection resulted in impaired cardiac function, pericardial edema, and increased cell death relative to Con-LC, culminating in compromised survival with 100% mortality within 2 wk, independent of AL fibril deposition. Prior work has implicated noncanonical p38 MAPK activation in the pathogenesis of AL-LC-induced cardiotoxicity, and p38 MAPK inhibition via SB-203580 rescued AL-LC-induced cardiac dysfunction and cell death and attenuated mortality in zebrafish. This in vivo zebrafish model of AL-LC cardiotoxicity demonstrates that antagonism of p38 MAPK within the AL-LC cardiotoxic signaling response may serve to improve cardiac function and mortality in AL cardiomyopathy. Furthermore, this in vivo model system will allow for further study of the molecular underpinnings of AL cardiotoxicity and identification of novel therapeutic strategies.

Monolithic translucent BaMgAl 10O 17:Eu 2+ phosphors for laser-driven solid state lighting

DOE PAGES

Cozzan, Clayton; Brady, Michael J.; O’Dea, Nicholas; ...

2016-10-11

With high power light emitting diodes and laser diodes being explored for white light generation and visible light communication, thermally robust encapsulation schemes for color-converting inorganic phosphors are essential. In the current work, the canonical blue-emitting phosphor, high purity Eu-doped BaMgAl 10O 17, has been prepared using microwave-assisted heating (25 min) and densified into translucent ceramic phosphor monoliths using spark plasma sintering (30 min). Lastly, the resulting translucent ceramic monoliths convert UV laser light to blue light with the same efficiency as the starting powder and provide superior thermal management in comparison with silicone encapsulation.

Effects of Al-Impurity Type on Formation Energy, Crystal Structure, Electronic Structure, and Optical Properties of ZnO by Using Density Functional Theory and the Hubbard-U Method.

PubMed

Wu, Hsuan-Chung; Chen, Hsing-Hao; Zhu, Yu-Ren

2016-08-01

We systematically investigated the effects of Al-impurity type on the formation energy, crystal structure, charge density, electronic structure, and optical properties of ZnO by using density functional theory and the Hubbard-U method. Al-related defects, such as those caused by the substitution of Zn and O atoms by Al atoms (Al s(Zn) and Al s(O) , respectively) and the presence of an interstitial Al atom at the center of a tetrahedron (Al i(tet) ) or an octahedron (Al i(oct) ), and various Al concentrations were evaluated. The calculated formation energy follows the order E f (Al s(Zn) ) < E f (Al i(tet) ) < E f (Al i(oct) ) < E f (Al s(O) ). Electronic structure analysis showed that the Al s(Zn) , Al s(O) , Al i(tet) , and Al i(oct) models follow n -type conduction, and the optical band gaps are higher than that of pure ZnO. The calculated carrier concentrations of the Al s(O) and Al i(tet) /Al i(oct) models are higher than that of the Al s(Zn) model. However, according to the curvature of the band structure, the occurrence of interstitial Al atoms or the substitution of O atoms by Al atoms results in a high effective mass, possibly reducing the carrier mobility. The average transmittance levels in the visible light and ultraviolet (UV) regions of the Al s(Zn) model are higher than those of pure ZnO. However, the presence of an interstitial Al atom within the ZnO crystal reduces transmittance in the visible light region; Al s(O) substantially reduces the transmittance in the visible light and UV regions. In addition, the properties of ZnO doped with various Al s(Zn) concentrations were analyzed.

Dungeons, Gratings, and Black Rooms: A Defense of Double-Anchoring Theory and a Reply to Howe et al. (2007)

ERIC Educational Resources Information Center

Bressan, Paola

2007-01-01

Replies to comments mad by Howe et al. on the current author's original article. The double-anchoring theory of lightness (P. Bressan, 2006b) assumes that any given region belongs to a set of frameworks, created by Gestalt grouping principles, and receives a provisional lightness within each of them; the region's final lightness is a weighted…

High harmonic generation in a gas-filled hollow-core photonic crystal fiber

NASA Astrophysics Data System (ADS)

Heckl, O. H.; Baer, C. R. E.; Kränkel, C.; Marchese, S. V.; Schapper, F.; Holler, M.; Südmeyer, T.; Robinson, J. S.; Tisch, J. W. G.; Couny, F.; Light, P.; Benabid, F.; Keller, U.

2009-10-01

High harmonic generation (HHG) of intense infrared laser radiation (Ferray et al., J. Phys. B: At. Mol. Opt. Phys. 21:L31, 1988; McPherson et al., J. Opt. Soc. Am. B 4:595, 1987) enables coherent vacuum-UV (VUV) to soft-X-ray sources. In the usual setup, energetic femtosecond laser pulses are strongly focused into a gas jet, restricting the interaction length to the Rayleigh range of the focus. The average photon flux is limited by the low conversion efficiency and the low average power of the complex laser amplifier systems (Keller, Nature 424:831, 2003; Südmeyer et al., Nat. Photonics 2:599, 2008; Röser et al., Opt. Lett. 30:2754, 2005; Eidam et al., IEEE J. Sel. Top. Quantum Electron. 15:187, 2009) which typically operate at kilohertz repetition rates. This represents a severe limitation for many experiments using the harmonic radiation in fields such as metrology or high-resolution imaging. Driving HHG with novel high-power diode-pumped multi-megahertz laser systems has the potential to significantly increase the average photon flux. However, the higher average power comes at the expense of lower pulse energies because the repetition rate is increased by more than a thousand times, and efficient HHG is not possible in the usual geometry. So far, two promising techniques for HHG at lower pulse energies were developed: external build-up cavities (Gohle et al., Nature 436:234, 2005; Jones et al., Phys. Rev. Lett. 94:193, 2005) and resonant field enhancement in nanostructured targets (Kim et al., Nature 453:757, 2008). Here we present a third technique, which has advantages in terms of ease of HHG light extraction, transverse beam quality, and the possibility to substantially increase conversion efficiency by phase-matching (Paul et al., Nature 421:51, 2003; Ren et al., Opt. Express 16:17052, 2008; Serebryannikov et al., Phys. Rev. E (Stat. Nonlinear Soft Matter Phys.) 70:66611, 2004; Serebryannikov et al., Opt. Lett. 33:977, 2008; Zhang et al., Nat. Phys. 3:270, 2007). The interaction between the laser pulses and the gas occurs in a Kagome-type Hollow-Core Photonic Crystal Fiber (HC-PCF) (Benabid et al., Science 298:399, 2002), which reduces the detection threshold for HHG to only 200 nJ. This novel type of fiber guides nearly all of the light in the hollow core (Couny et al., Science 318:1118, 2007), preventing damage even at intensities required for HHG. Our fiber guided 30-fs pulses with a pulse energy of more than 10 μJ, which is more than five times higher than for any other photonic crystal fiber (Hensley et al., Conference on Lasers and Electro-Optics (CLEO), IEEE Press, New York, 2008).

Matrix Metalloproteinases and their Tissue Inhibitors in Cardiac Amyloidosis: Relationship to Structural, Functional Myocardial Changes and to Light Chain Amyloid Deposition

PubMed Central

Biolo, Andreia; Ramamurthy, Sujata; Connors, Lawreen H.; O'Hara, Carl J.; Meier-Ewert, Hans K.; Hoo, Pamela T. Soo; Sawyer, Douglas B.; Seldin, David S.; Sam, Flora

2009-01-01

Background Cardiac amyloidosis is characterized by amyloid infiltration resulting in extracellular matrix (ECM) disruption. Amyloid cardiomyopathy due to immunoglobulin light chain protein (AL-CMP) deposition, has an accelerated clinical course and a worse prognosis compared to non-light chain cardiac amyloidoses i.e., forms associated with wild-type or mutated transthyretin (TTR). We therefore tested the hypothesis that determinants of proteolytic activity of the ECM, the matrix metalloproteinases (MMPs) and their tissue inhibitors (TIMPs), would have distinct patterns and contribute to the pathogenesis of AL-CMP vs. TTR. Methods / Results We studied 40 patients with systemic amyloidosis: 10 AL-CMP patients, 20 patients with TTR-associated forms of cardiac amyloidosis, i.e. senile systemic amyloidois (SSA, involving wild-type TTR) or mutant TTR (ATTR), and 10 patients with AL amyloidosis without cardiac involvement. Serum MMP-2 and −9, TIMP-1, −2 and −4, brain natriuretic peptide (BNP) values and echocardiography were determined. AL-CMP and SSA-ATTR groups had similar degrees of increased left ventricular wall thickness (LVWT). However, BNP, MMP-9 and TIMP-1 levels were distinctly elevated accompanied by marked diastolic dysfunction in the AL-CMP group vs. no or minimal increases in the SSA-ATTR group. BNP, MMPs and TIMPs were not correlated with the degree of LVWT but were correlated to each other and to measures of diastolic dysfunction. Immunostaining of human endomyocardial biopsies showed diffuse expression of MMP-9 and TIMP-1 in AL-CMP and limited expression in SSA or ATTR hearts. Conclusions Despite comparable LVWT with TTR-related cardiac amyloidosis, AL-CMP patients have higher BNP, MMPs and TIMPs, which correlated with diastolic dysfunction. These findings suggest a relationship between light chains and ECM proteolytic activation that may play an important role in the functional and clinical manifestations of AL-CMP, distinct from the other non-light chain cardiac amyloidoses. PMID:19808299

Survey and Alighment for the ALS Project at LBL Berkeley

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

Keller, R.; Lauritzen, T.; /LBL, Berkeley

2005-08-12

The Advanced Light Source (ALS), now under construction at Lawrence Berkeley Laboratory, is a synchrotron radiation source of the third generation designed to produce extremely bright photon beams in the UV and soft X-ray regions. Its main accelerator components are a 1-1.9 GeV electron storage ring with 196.8 m circumference and 12 super-periods, a 1.5 GeV booster synchrotron with 75.0 m circumference and 4 super-periods, and a 50 MeV linac, as shown in Fig. 1. The storage ring has particularly tight positioning tolerances for lattice magnets and other components to assure the required operational characteristics. The general survey and alignmentmore » concept for the ALS is based on a network of fixed monuments installed in the building floor, to which all component positions are referred. Measurements include electronic distance measurements and separate sightings for horizontal and vertical directions, partially with automated electronic data capture. Most of the data processing is accomplished by running a customized version of PC-GEONET. It provides raw data storage, data reduction, and the calculation of adjusted coordinates, as well as an option for error analysis. PC-GEONET has also been used to establish an observation plan for the monuments and calculate their expected position accuracies, based on approximate coordinates. Additionally, for local survey tasks, the commercial software package ECDS is used. In this paper, the ALS survey and alignment strategy and techniques are presented and critically discussed. First experiences with the alignment of the linac and booster components are described.« less

A NEW GUI FOR GLOBAL ORBIT CORRECTION AT THE ALS USING MATLAB

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

Pachikara, J.; Portmann, G.

2007-01-01

Orbit correction is a vital procedure at particle accelerators around the world. The orbit correction routine currently used at the Advanced Light Source (ALS) is a bit cumbersome and a new Graphical User Interface (GUI) has been developed using MATLAB. The correction algorithm uses a singular value decomposition method for calculating the required corrector magnet changes for correcting the orbit. The application has been successfully tested at the ALS. The GUI display provided important information regarding the orbit including the orbit errors before and after correction, the amount of corrector magnet strength change, and the standard deviation of the orbitmore » error with respect to the number of singular values used. The use of more singular values resulted in better correction of the orbit error but at the expense of enormous corrector magnet strength changes. The results showed an inverse relationship between the peak-to-peak values of the orbit error and the number of singular values used. The GUI interface helps the ALS physicists and operators understand the specifi c behavior of the orbit. The application is convenient to use and is a substantial improvement over the previous orbit correction routine in terms of user friendliness and compactness.« less

Multiwavelength Photometric Imaging of X-Ray and EUV Emission from Comet P/Tempel-Tuttle 1998

NASA Technical Reports Server (NTRS)

Lisse, Carey M.

2004-01-01

The unexpected discovery of x-ray emission from Comet Hyakutake in March 1996 (Lisse et ai. 1996) has produced a number of questions about the physical mechanism producing the radiation. The original detection and subsequent observations (Dennerl et ai. 1997, Mumma et al. 1997, Krasnopolsky et al. 1998, Owens et al. 1998. Lisse et al. 1999) have shown that the very soft (best fit thermal bremsstrahlung model kT approx. 0.2 keV) emission is due to an interaction between the solar wind and the comet's atmosphere. Using the results fiom the 15 comets detected to date in x-rays, we report on the latest results on cometary x-ray emission, including new results from Chandra and XMM. As-observed morphologies, spectra, and light curves will be discussed. Our emphasis will be on understanding the physical mechanism producing the emission, and using this to determine the nature of the cometary coma, the structure of the solar wind in the heliosphere, and the source of the local soft x-ray background. This work has been graciously supported by grants from the NASA Planetary Astronomy and Astrophysical Data Programs.

Spatial Variability in Black Carbon Mixing State Observed During The Multi-City NASA DISCOVER-AQ Field Campaign

NASA Astrophysics Data System (ADS)

Moore, R.; Ziemba, L. D.; Beyersdorf, A. J.; Chen, G.; Corr, C.; Hudgins, C.; Martin, R.; Shook, M.; Thornhill, K. L., II; Winstead, E.; Anderson, B. E.

2014-12-01

Light absorbing carbonaceous aerosols are known to be an important climatic driver with a global radiative forcing of about half (IPCC, 2013) to two-thirds (Bond et al., 2013) that of the dominant greenhouse gas, carbon dioxide. While the mass absorption coefficient of pure black carbon (BC) is fairly well known, observational evidence suggests that BC rapidly mixes with other aerosol chemical components within hours of emission (Moffet and Prather, 2009; Moteki et al., 2007). These other components may include predominantly scattering organic, sulfate, and nitrate species, as well as light-absorbing, so-called "brown carbon" (BrC). It has been suggested that the presence of these BC-mixed components may induce mixing-state-dependent lensing effects that could potentially double the BC direct radiative forcing (Jacobson, 2001). The key to better understanding how BC-rich aerosols are distributed in the atmosphere is to examine an unbiased set of measurements covering broad spatial and temporal coverage; however, many past airborne field campaigns have specifically targeted source plumes or other scientifically-relevant emissions sources. The recent NASA DISCOVER-AQ campaign is unique in that approximately the same flight pattern was performed over a month-long period in each of four different U.S. metropolitan areas, ensuring an unbiased, or at least less biased, data set with both wide horizontal and vertical (surface to 5 km altitude) coverage. We present a statistical analysis of BC-rich particle mixing state measured during DISCOVER-AQ by a DMT Single Particle Soot Photometer (SP2). The SP2 measures the BC mass distribution via laser incandescence, and the non-BC coating thickness is inferred from the light scattering signal of particles greater than 200 nm in diameter (Gao et al., 2007; Moteki and Kondo, 2008). The SP2-derived size distributions are compared to optical scattering size distributions measured by an UHSAS in order determine 1) the externally mixed fraction of particles containing BC across the optically-active region of the size distribution (200-1000 nm) and 2) the internally mixed volume fraction of BC relative to the total particle volume assuming spherical particles. Vertical profiles of these variables are discussed in the context of remotely sensing aerosol mixing state.

Fabrications and application of single crystalline GaN for high-performance deep UV photodetectors

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

Velazquez, R.; Rivera, M.; Feng, P., E-mail: p.feng@upr.edu

2016-08-15

High-quality single crystalline Gallium Nitride (GaN) semiconductor has been synthesized using molecule beam epitaxy (MBE) technique for development of high-performance deep ultraviolet (UV) photodetectors. Thickness of the films was estimated by using surface profile meter and scanning electron microscope. Electronic states and elemental composition of the films were obtained using Raman scattering spectroscopy. The orientation, crystal structure and phase purity of the films were examined using a Siemens x-ray diffractometer radiation. The surface microstructure was studied using high resolution scanning electron microscopy (SEM). Two types of metal pairs: Al-Al, Al-Cu or Cu-Cu were used for interdigital electrodes on GaN filmmore » in order to examine the Schottky properties of the GaN based photodetector. The characterizations of the fabricated prototype include the stability, responsivity, response and recovery times. Typical time dependent photoresponsivity by switching different UV light source on and off five times for each 240 seconds at a bias of 2V, respectively, have been obtained. The detector appears to be highly sensitive to various UV wavelengths of light with very stable baseline and repeatability. The obtained photoresponsivity was up to 354 mA/W at the bias 2V. Higher photoresponsivity could be obtained if higher bias was applied but it would unavoidably result in a higher dark current. Thermal effect on the fabricated GaN based prototype was discussed.« less

Mineralogy and geochemistry of the Lower Cretaceous siliciclastic rocks of the Morita Formation, Sierra San José section, Sonora, Mexico

NASA Astrophysics Data System (ADS)

Madhavaraju, J.; Pacheco-Olivas, S. A.; González-León, Carlos M.; Espinoza-Maldonado, Inocente G.; Sanchez-Medrano, P. A.; Villanueva-Amadoz, U.; Monreal, Rogelio; Pi-Puig, T.; Ramírez-Montoya, Erik; Grijalva-Noriega, Francisco J.

2017-07-01

Clay mineralogy and geochemical studies were carried out on sandstone and shale samples collected from the Sierra San José section of the Morita Formation to infer the paleoclimate and paleoweathering conditions that prevailed in the source region during the deposition of these sediments. The clay mineral assemblages (fraction < 2 μm) of the Sierra San José section are composed of chlorite and illite. The abundance of illite and chlorite in the studied samples suggest that the physical weathering conditions were dominant over chemical weathering. Additionally, the illite and chlorite assemblages reflect arid or semi-arid climatic conditions in the source regions. K2O/Al2O3 ratio of shales vary between 0.15 and 0.26, which lie in the range of values for clay minerals, particularly illite composition. Likewise, sandstones vary between 0.06 and 0.13, suggesting that the clay minerals are mostly kaolinte and illite types. On the chondrite-normalized diagrams, sandstone and shale samples show enriched light rare earth elements (LREE), flat heavy rare earth elements (HREE) patterns and negative Eu anomalies. The CIA and PIA values and A-CN-K plot of shales indicate low to moderate degree of weathering in the source regions. However, the sandstones have moderate to high values of CIA and PIA suggesting a moderate to intense weathering in the source regions. The SiO2/Al2O3 ratios, bivariate and ternary plots, discriminant function diagram and elemental ratios indicate the felsic source rocks for sandstone and shale of the Morita Formation.

LED deep UV source for charge management of gravitational reference sensors

NASA Astrophysics Data System (ADS)

Sun, Ke-Xun; Allard, Brett; Buchman, Saps; Williams, Scott; Byer, Robert L.

2006-04-01

Proof mass electrical charge management is an important functionality for the ST-7-LTP technology demonstration flight and for LISA. Photoemission for charge control is accomplished by using deep ultraviolet (UV) light to excite photoelectron emission from an Au alloy. The conventional UV source is a mercury vapour lamp. We propose and demonstrate charge management using a deep UV light emitting diode (LED) source. We have acquired selected AlGaN UV LEDs, characterized their performance and successfully used them to realize charge management. The UV LEDs emit at a 257 nm central wavelength with a bandwidth of ~12 nm. The UV power for a free-space LED is ~120 µW, and after fibre coupling is ~16 µW, more than sufficient for LISA applications. We have directly observed the LED UV light-induced photocurrent response from an Au photocathode and an Au-coated GRS/ST-7 proof mass. We demonstrated fast switching of UV LEDs and associated fast changes in photocurrent. This allows modulation and continuous discharge to meet stringent LISA disturbance reduction requirements. We propose and demonstrate AC charge management outside the gravitational wave signal band. Further, the megahertz bandwidth for UV LED switching allows for up to six orders of magnitude dynamic power range and a number of novel modes of operations. The UV LED based charge management system offers the advantages of small-size, lightweight, fibre-coupled operation with very low power consumption. Presented at 'Amaldi6', Poster 73, Space Detector, 6th Edoardo Almadi Conference on Gravitational Waves, 20-24 June 2005.

A Genetic Selection For Neurospora crassa Mutants Altered in Their Light Regulation of Transcription

PubMed Central

Navarro-Sampedro, Laura; Yanofsky, Charles; Corrochano, Luis M.

2008-01-01

Transcription of the Neurospora crassa gene con-10 is induced during conidiation and following exposure of vegetative mycelia to light, but light activation is transient due to photoadaptation. We describe mutational analyses of photoadaptation using a N. crassa strain bearing a translational fusion of con-10, including its regulatory region, to a selectable bacterial gene conferring hygromycin resistance (hph). Growth of this strain was sensitive to hygromycin, upon continuous culture in the light. Five mutants were isolated that were resistant to hygromycin when cultured under constant light. Three mutant strains displayed elevated, sustained accumulation of con-10∷hph mRNA during continued light exposure, suggesting that they bear mutations that reduce or eliminate the presumed light-dependent repression mechanism that blocks con-10 transcription upon prolonged illumination. These mutations altered photoadaptation for only a specific group of genes (con-10 and con-6), suggesting that regulation of photoadaptation is relatively gene specific. The mutations increased light-dependent mRNA accumulation for genes al-1, al-2, and al-3, each required for carotenoid biosynthesis, resulting in a threefold increase in carotenoid accumulation following continuous light exposure. Identification of the altered gene or genes in these mutants may reveal novel proteins that participate in light regulation of gene transcription in fungi. PMID:18202366

Down-conversion phosphors as noble-metal-free co-catalyst in ZnO for efficient visible light photocatalysis

NASA Astrophysics Data System (ADS)

Chu, Haipeng; Liu, Xinjuan; Liu, Jiaqing; Lei, Wenyan; Li, Jinliang; Wu, Tianyang; Li, Ping; Li, Huili; Pan, Likun

2017-01-01

Exploring novel visible light responsive photocatalysts is one of greatly significant issues from the viewpoint of using solar energy. Here we report the yellow-orange emitting α-Si3N4-doped Lu3Al5O12:Ce3+ (Lu3Al5-xSixO12-xNx:Ce3+) phosphors as a noble-metal-free co-catalyst for enhanced visible light photocatalytic activity of ZnO. The results show that ZnO-Lu3Al5-xSixO12-xNx:Ce3+ hybrid photocatalysts using a fast microwave-assisted approach exhibits a 91% methylene blue (MB) degradation under visible light irradiation at 240 min, which evidence the synergistic effect of ZnO and Lu3Al5-xSixO12-xNx:Ce3+ that suppress the rate of charge recombination and increase the self-sensitized degradation of MB. ZnO-down conversion phosphors can be envisaged as potential candidate in environmental engineering and solar energy applications.

Heating device for semiconductor wafers

DOEpatents

Vosen, Steven R.

1999-01-01

An apparatus for heat treating semiconductor wafers is disclosed. The apparatus includes a heating device which contains an assembly of light energy sources for emitting light energy onto a wafer. In particular, the light energy sources are positioned such that many different radial heating zones are created on a wafer being heated. For instance, in one embodiment, the light energy sources form a spiral configuration. In an alternative embodiment, the light energy sources appear to be randomly dispersed with respect to each other so that no discernable pattern is present. In a third alternative embodiment of the present invention, the light energy sources form concentric rings. Tuning light sources are then placed in between the concentric rings of light.

Heating device for semiconductor wafers

DOEpatents

Vosen, S.R.

1999-07-27

An apparatus for heat treating semiconductor wafers is disclosed. The apparatus includes a heating device which contains an assembly of light energy sources for emitting light energy onto a wafer. In particular, the light energy sources are positioned such that many different radial heating zones are created on a wafer being heated. For instance, in one embodiment, the light energy sources form a spiral configuration. In an alternative embodiment, the light energy sources appear to be randomly dispersed with respect to each other so that no discernible pattern is present. In a third alternative embodiment of the present invention, the light energy sources form concentric rings. Tuning light sources are then placed in between the concentric rings of light. 4 figs.

Exposure to Sunlight Reduces the Risk of Myopia in Rhesus Monkeys

PubMed Central

Wang, Yong; Ding, Hui; Stell, William K.; Liu, Liangping; Li, Saiqun; Liu, Hongshan; Zhong, Xingwu

2015-01-01

Exposure to sunlight has recently been postulated as responsible for the effect that more time spent outdoors protects children from myopia, while early life exposure to natural light was reported to be possibly related to onset of myopia during childhood. In this study, we had two aims: to determine whether increasing natural light exposure has a protective effect on hyperopic defocus-induced myopia, and to observe whether early postnatal exposure to natural light causes increased risk of refractive error in adolescence. Eight rhesus monkeys (aged 20-30 days) were treated monocularly with hyperopic-defocus (-3.0D lens) and divided randomly into two groups: AL group (n=4), reared under Artificial (indoor) Lighting (08:00-20:00); and NL group (n=4), exposed to Natural (outdoor) Light for 3 hours per day (11:00-14:00), and to indoor lighting for the rest of the light phase. After being reared with lenses for ca. 190 days, all monkeys were returned to unrestricted vision until the age of 3 years. Another eight age-matched monkeys, reared with unrestricted vision under artificial lighting since birth, were employed as controls. The ocular refraction, corneal curvature and axial dimensions were measured before lens-wearing (at 23±3 days of age), monthly during the light phase, and at the age of puberty (at 1185+3 days of age). During the lens-wearing treatment, infant monkeys in the NL group were more hyperopic than those in the AL group (F=5.726, P=0.032). Furthermore, the two eyes of most NL monkeys remained isometropic, whereas 3 of 4 AL monkeys developed myopic anisometropia more than -2.0D. At adolescence, eyes of AL monkeys showed significant myopic anisometropia compared with eyes of NL monkeys (AL vs NL: -1.66±0.87D vs -0.22±0.44D; P=0.002) and controls (AL vs Control: -1.66±0.87D vs -0.05±0.85D; P<0.0001). All differences in refraction were associated with parallel changes in axial dimensions. Our results suggest that exposure to natural outdoor light might have an effect to reduced hyperopic defocus-induced myopia. Also, the data imply that early life exposure to sunlight may help to maintain normal development of emmetropization later in life, and thus lower the risk of myopic anisometropia in adolescent monkey. PMID:26030845

Photomorphogenesis, photosynthesis, and seed yield of wheat plants grown under red light-emitting diodes (LEDs) with and without supplemental blue lighting

NASA Technical Reports Server (NTRS)

Goins, G. D.; Yorio, N. C.; Sanwo, M. M.; Brown, C. S.; Sager, J. C. (Principal Investigator)

1997-01-01

Red light-emitting diodes (LEDs) are a potential light source for growing plants in spaceflight systems because of their safety, small mass and volume, wavelength specificity, and longevity. Despite these attractive features, red LEDs must satisfy requirements for plant photosynthesis and photomorphogenesis for successful growth and seed yield. To determine the influence of gallium aluminium arsenide (GaAlAs) red LEDs on wheat photomorphogenesis, photosynthesis, and seed yield, wheat (Triticum aestivum L., cv. 'USU-Super Dwarf') plants were grown under red LEDs and compared to plants grown under daylight fluorescent (white) lamps and red LEDs supplemented with either 1% or 10% blue light from blue fluorescent (BF) lamps. Compared to white light-grown plants, wheat grown under red LEDs alone demonstrated less main culm development during vegetative growth through preanthesis, while showing a longer flag leaf at 40 DAP and greater main culm length at final harvest (70 DAP). As supplemental BF light was increased with red LEDs, shoot dry matter and net leaf photosynthesis rate increased. At final harvest, wheat grown under red LEDs alone displayed fewer subtillers and a lower seed yield compared to plants grown under white light. Wheat grown under red LEDs+10% BF light had comparable shoot dry matter accumulation and seed yield relative to wheat grown under white light. These results indicate that wheat can complete its life cycle under red LEDs alone, but larger plants and greater amounts of seed are produced in the presence of red LEDs supplemented with a quantity of blue light.

Immunoglobulin Light Chains Form an Extensive and Highly Ordered Fibril Involving the N- and C-Termini

PubMed Central

2017-01-01

Light-chain (AL)-associated amyloidosis is a systemic disorder involving the formation and deposition of immunoglobulin AL fibrils in various bodily organs. One severe instance of AL disease is exhibited by the patient-derived variable domain (VL) of the light chain AL-09, a 108 amino acid residue protein containing seven mutations relative to the corresponding germline protein, κI O18/O8 VL. Previous work has demonstrated that the thermodynamic stability of native AL-09 VL is greatly lowered by two of these mutations, Y87H and N34I, whereas a third mutation, K42Q, further increases the kinetics of fibril formation. However, detailed knowledge regarding the residues that are responsible for stabilizing the misfolded fibril structure is lacking. In this study, using solid-state NMR spectroscopy, we show that the majority of the AL-09 VL sequence is immobilized in the fibrils and that the N- and C-terminal portions of the sequence are particularly well-structured. Thus, AL-09 VL forms an extensively ordered and β-strand-rich fibril structure. Furthermore, we demonstrate that the predominant β-sheet secondary structure and rigidity observed for in vitro prepared AL-09 VL fibrils are qualitatively similar to those observed for AL fibrils extracted from postmortem human spleen tissue, suggesting that this conformation may be representative of a common feature of AL fibrils. PMID:28261692

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

Djavid, Mehrdad; Mi, Zetian, E-mail: zetian.mi@mcgill.ca

The performance of conventional AlGaN deep ultraviolet light emitting diodes has been limited by the extremely low light extraction efficiency (<10%), due to the unique transverse magnetic (TM) polarized light emission. Here, we show that, by exploiting the lateral side emission, the extraction efficiency of TM polarized light can be significantly enhanced in AlGaN nanowire structures. Using the three-dimensional finite-difference time domain simulation, we demonstrate that the nanowire structures can be designed to inhibit the emission of guided modes and redirect trapped light into radiated modes. A light extraction efficiency of more than 70% can, in principle, be achieved bymore » carefully optimizing the nanowire size, nanowire spacing, and p-GaN thickness.« less

Nonimaging Optical Illumination System

DOEpatents

Winston, Roland

1994-08-02

A nonimaging illumination optical device for producing selected intensity output over an angular range. The device includes a light reflecting surface (24, 26) around a light source (22) which is disposed opposite the aperture opening of the light reflecting surface (24, 26). The light source (22) has a characteristic dimension which is small relative to one or more of the distance from the light source (22) to the light reflecting surface (24, 26) or the angle subtended by the light source (22) at the light reflecting surface (24, 26).

Synchrotron Photoionization Investigation of the Oxidation of Ethyl tert-Butyl Ether.

PubMed

Winfough, Matthew; Yao, Rong; Ng, Martin; Catani, Katherine; Meloni, Giovanni

2017-02-23

The oxidation of ethyl tert-butyl ether (ETBE), a widely used fuel oxygenated additive, is investigated using Cl atoms as initiators in the presence of oxygen. The reaction is carried out at 293, 550, and 700 K. Reaction products are probed by a multiplexed chemical kinetics photoionization mass spectrometer coupled with the synchrotron radiation produced at the Advanced Light Source (ALS) of the Lawrence Berkeley National Laboratory. Products are identified on the basis of mass-to-charge ratio, ionization energies, and shape of photoionization spectra. Reaction pathways are proposed together with detected primary products.

CFEL-ASG Software Suite (CASS): usage for free-electron laser experiments with biological focus.

PubMed

Foucar, Lutz

2016-08-01

CASS [Foucar et al. (2012). Comput. Phys. Commun. 183 , 2207-2213] is a well established software suite for experiments performed at any sort of light source. It is based on a modular design and can easily be adapted for use at free-electron laser (FEL) experiments that have a biological focus. This article will list all the additional functionality and enhancements of CASS for use with FEL experiments that have been introduced since the first publication. The article will also highlight some advanced experiments with biological aspects that have been performed.

Recent Major Improvements to the ALS Sector 5 MacromolecularCrystallography Beamlines

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

Morton, Simon A.; Glossinger, James; Smith-Baumann, Alexis

2007-07-01

Although the Advanced Light Source (ALS) was initially conceived primarily as a low energy (1.9GeV) 3rd generation source of VUV and soft x-ray radiation it was realized very early in the development of the facility that a multipole wiggler source coupled with high quality, (brightness preserving), optics would result in a beamline whose performance across the optimal energy range (5-15keV) for macromolecular crystallography (MX) would be comparable to, or even exceed, that of many existing crystallography beamlines at higher energy facilities. Hence, starting in 1996, a suite of three beamlines, branching off a single wiggler source, was constructed, which togethermore » formed the ALS Macromolecular Crystallography Facility. From the outset this facility was designed to cater equally to the needs of both academic and industrial users with a heavy emphasis placed on the development and introduction of high throughput crystallographic tools, techniques, and facilities--such as large area CCD detectors, robotic sample handling and automounting facilities, a service crystallography program, and a tightly integrated, centralized, and highly automated beamline control environment for users. This facility was immediately successful, with the primary Multiwavelength Anomalous Diffraction beamline (5.0.2) in particular rapidly becoming one of the foremost crystallographic facilities in the US--responsible for structures such as the 70S ribosome. This success in-turn triggered enormous growth of the ALS macromolecular crystallography community and spurred the development of five additional ALS MX beamlines all utilizing the newly developed superconducting bending magnets ('superbends') as sources. However in the years since the original Sector 5.0 beamlines were built the performance demands of macromolecular crystallography users have become ever more exacting; with growing emphasis placed on studying larger complexes, more difficult structures, weakly diffracting or smaller crystals, and on more rapidly screening larger numbers of candidate crystals; all of these requirements translate directly into a pressing need for increased flux, a tighter beam focus and faster detectors. With these growing demands in mind a major program of beamline and detector upgrades was initiated in 2004 with the goal of dramatically enhancing all aspects of beamline performance. Approximately $3 million in funding from diverse sources including NIH, LBL, the ALS, and the industrial and academic members of the beamline Participating Research Team (PRT), has been employed to develop and install new high performance beamline optics and to purchase the latest generation of CCD detectors. This project, which reached fruition in early 2007, has now fulfilled all of its original goals--boosting the flux on all three beamlines by up to 20-fold--with a commensurate reduction in exposure and data acquisition times for users. The performance of the Sector 5.0 beamlines is now comparable to that of the latest generation ALS superbend beamlines and, in the case of beamline 5.0.2, even surpasses it by a considerable margin. Indeed, the present performance of this beamline is now, once again, comparable to that envisioned for many MX beamlines planned or under construction on newer or higher energy machines.« less

An experimental apparatus for diffraction-limited soft x-ray nano-focusing

NASA Astrophysics Data System (ADS)

Merthe, Daniel J.; Goldberg, Kenneth A.; Yashchuk, Valeriy V.; Yuan, Sheng; McKinney, Wayne R.; Celestre, Richard; Mochi, Iacopo; Macdougall, James; Morrison, Gregory Y.; Rakawa, Senajith B.; Anderson, Erik; Smith, Brian V.; Domning, Edward E.; Warwick, Tony; Padmore, Howard

2011-09-01

Realizing the experimental potential of high-brightness, next generation synchrotron and free-electron laser light sources requires the development of reflecting x-ray optics capable of wavefront preservation and high-resolution nano-focusing. At the Advanced Light Source (ALS) beamline 5.3.1, we are developing broadly applicable, high-accuracy, in situ, at-wavelength wavefront measurement techniques to surpass 100-nrad slope measurement accuracy for diffraction-limited Kirkpatrick-Baez (KB) mirrors. The at-wavelength methodology we are developing relies on a series of wavefront-sensing tests with increasing accuracy and sensitivity, including scanning-slit Hartmann tests, grating-based lateral shearing interferometry, and quantitative knife-edge testing. We describe the original experimental techniques and alignment methodology that have enabled us to optimally set a bendable KB mirror to achieve a focused, FWHM spot size of 150 nm, with 1 nm (1.24 keV) photons at 3.7 mrad numerical aperture. The predictions of wavefront measurement are confirmed by the knife-edge testing. The side-profiled elliptically bent mirror used in these one-dimensional focusing experiments was originally designed for a much different glancing angle and conjugate distances. Visible-light long-trace profilometry was used to pre-align the mirror before installation at the beamline. This work demonstrates that high-accuracy, at-wavelength wavefront-slope feedback can be used to optimize the pitch, roll, and mirror-bending forces in situ, using procedures that are deterministic and repeatable.

Development of a circadian light source

NASA Astrophysics Data System (ADS)

Nicol, David B.; Ferguson, Ian T.

2002-11-01

Solid state lighting presents a new paradigm for lighting - controllability. Certain characteristics of the lighting environment can be manipulated, because of the possibility of using multiple LEDs of different emission wavelengths as the illumination source. This will provide a new, versatile, general illumination source due to the ability to vary the spectral power distribution. New effects beyond the visual may be achieved that are not possible with conventional light sources. Illumination has long been the primary function of lighting but as the lighting industry has matured the psychological aspects of lighting have been considered by designers; for example, choosing a particular lighting distribution or color variation in retail applications. The next step in the evolution of light is to consider the physiological effects of lighting that cause biological changes in a person within the environment. This work presents the development of a source that may have important bearing on this area of lighting. A circadian light source has been developed to provide an illumination source that works by modulating its correlated color temperature to mimic the changes in natural daylight through the day. In addition, this source can cause or control physiological effects for a person illuminated by it. The importance of this is seen in the human circadian rhythm's peak response corresponding to blue light at ~460 nm which corresponds to the primary spectral difference in increasing color temperature. The device works by adding blue light to a broadband source or mixing polychromatic light to mimic the variation of color temperature observed for the Planckian Locus on the CIE diagram. This device can have several applications including: a tool for researchers in this area, a general illumination lighting technology, and a light therapy device.

A tuneable approach to uniform light distribution for artificial daylight photodynamic therapy.

PubMed

O'Mahoney, Paul; Haigh, Neil; Wood, Kenny; Brown, C Tom A; Ibbotson, Sally; Eadie, Ewan

2018-06-16

Implementation of daylight photodynamic therapy (dPDT) is somewhat limited by variable weather conditions. Light sources have been employed to provide artificial dPDT indoors, with low irradiances and longer treatment times. Uniform light distribution across the target area is key to ensuring effective treatment, particularly for large areas. A novel light source is developed with tuneable direction of light emission in order to meet this challenge. Wavelength composition of the novel light source is controlled such that the protoporphyrin-IX (PpIX) weighed spectra of both the light source and daylight match. The uniformity of the light source is characterised on a flat surface, a model head and a model leg. For context, a typical conventional PDT light source is also characterised. Additionally, the wavelength uniformity across the treatment site is characterised. The PpIX-weighted spectrum of the novel light source matches with PpIX-weighted daylight spectrum, with irradiance values within the bounds for effective dPDT. By tuning the direction of light emission, improvements are seen in the uniformity across large anatomical surfaces. Wavelength uniformity is discussed. We have developed a light source that addresses the challenges in uniform, multiwavelength light distribution for large area artificial dPDT across curved anatomical surfaces. Copyright © 2018. Published by Elsevier B.V.

A novel yellow-emitting SrAlSi{sub 4}N{sub 7}:Ce{sup 3+} phosphor for solid state lighting: Synthesis, electronic structure and photoluminescence properties

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

Ruan, Jian; Laboratory of Glasses and Nanostructured Functional Materials, 122 Luoshi Road, Wuhan, Hubei 430070; Xie, Rong-Jun, E-mail: Xie.Rong-Jun@nims.go.jp

2013-12-15

Ce{sup 3+}-doped and Ce{sup 3+}/Li{sup +}-codoped SrAlSi{sub 4}N{sub 7} phosphors were synthesized by gas pressure sintering of powder mixtures of Sr{sub 3}N{sub 2}, AlN, α-Si{sub 3}N{sub 4}, CeN and Li{sub 3}N. The phase purity, electronic crystal structure, photoluminescence properties of SrAlSi{sub 4}N{sub 7}:Ce{sup 3+}(Ce{sup 3+}/Li{sup +}) were investigated in this work. The band structure calculated by the DMol{sup 3} code shows that SrAlSi{sub 4}N{sub 7} has a direct band gap of 3.87 eV. The single crystal analysis of Ce{sup 3+}-doped SrAlSi{sub 4}N{sub 7} indicates a disordered Si/Al distribution and nitrogen vacnacy defects. SrAlSi{sub 4}N{sub 7} was identified as a majormore » phase of the fired powders, and Sr{sub 5}Al{sub 5}Si{sub 21}N{sub 35}O{sub 2} and AlN as minor phases. Both Ce{sup 3+} and Ce{sup 3+}/Li{sup +} doped SrAlSi{sub 4}N{sub 7} phosphors can be efficiently excited by near-UV or blue light and show a broadband yellow emission peaking around 565 nm. A highest external quantum efficiency of 38.3% under the 450 nm excitation was observed for the Ce{sup 3+}/Li{sup +}-doped SrAlSi{sub 4}N{sub 7} (5 mol%). A white light LED lamp with color temperature of 6300 K and color rendering index of Ra=78 was achieved by combining Sr{sub 0.97}Al{sub 1.03}Si{sub 3.997}N/94/maccounttest14=t0005{sub 1}8193 {sub 7}:Ce{sup 3+}{sub 0.03} with a commercial blue InGaN chip. It indicates that SrAlSi{sub 4}N{sub 7}:Ce{sup 3+} is a promising yellow emitting down-conversion phosphor for white LEDs. - Graphical abstract: One-phosphor converted white light-emitting diode (LED) was fabricated by combining a blue LED chip and a yellow-emitting SrAlSi4N7:Ce{sup 3+} phosphor (see inset), which has the color rendering index of 78 and color temperature of 6300 K. - Highlights: • We reported a new yellow nitride phosphor suitable for solid state lighting. • We solved the crystal structure and evidenced a disordered Si/Al distribution. • We fabricated a high color rendering white LEDs by using a single SrAlSi4N7:Ce.« less

Micro optical fiber light source and sensor and method of fabrication thereof

DOEpatents

Kopelman, Raoul; Tan, Weihong; Shi, Zhong-You

1997-01-01

This invention relates generally to the development of and a method of fabricating a fiber optic micro-light source and sensor (50). An optical fiber micro-light source (50) is presented whose aperture is extremely small yet able to act as an intense light source. Light sources of this type have wide ranging applications, including use as micro-sensors (22) in NSOM. Micro-sensor light sources have excellent detection limits as well as photo stability, reversibility, and millisecond response times. Furthermore, a method for manufacturing a micro optical fiber light source is provided. It involves the photo-chemical attachment of an optically active material onto the end surface of an optical fiber cable which has been pulled to form an end with an extremely narrow aperture. More specifically, photopolymerization has been applied as a means to photo-chemically attach an optically active material (60). This process allows significant control of the size of the micro light source (50). Furthermore, photo-chemically attaching an optically active material (60) enables the implementation of the micro-light source in a variety of sensor applications.

Micro optical fiber light source and sensor and method of fabrication thereof

DOEpatents

Kopelman, Raoul; Tan, Weihong; Shi, Zhong-You

1994-01-01

This invention relates generally to the development of and a method of fabricating a micro optical fiber light source. An optical fiber micro-light source is presented whose aperture is extremely small yet able to act as an intense light source. Light sources of this type have wide ranging applications, including use as micro-sensors in NSOM. Micro-sensor light sources have excellent detection limits as well as photo stability, reversibility, and millisecond response times. Furthermore, a method for manufacturing a micro optical fiber light source is provided. It involves the photo-chemical attachment of an optically active material onto the end surface of an optical fiber cable which has been pulled to form an end with an extremely narrow aperture. More specifically, photopolymerization has been applied as a means to photo-chemically attach an optically active material. This process allows significant control of the size of the micro light source. Furthermore, photo-chemically attaching an optically active material enables the implementation of the micro-light source in a variety of sensor applications.

Micro optical fiber light source and sensor and method of fabrication thereof

DOEpatents

Kopelman, R.; Tan, W.; Shi, Z.Y.

1997-05-06

This invention relates generally to the development of and a method of fabricating a fiber optic micro-light source and sensor. An optical fiber micro-light source is presented whose aperture is extremely small yet able to act as an intense light source. Light sources of this type have wide ranging applications, including use as micro-sensors in NSOM. Micro-sensor light sources have excellent detection limits as well as photo stability, reversibility, and millisecond response times. Furthermore, a method for manufacturing a micro optical fiber light source is provided. It involves the photo-chemical attachment of an optically active material onto the end surface of an optical fiber cable which has been pulled to form an end with an extremely narrow aperture. More specifically, photopolymerization has been applied as a means to photo-chemically attach an optically active material. This process allows significant control of the size of the micro light source. Furthermore, photo-chemically attaching an optically active material enables the implementation of the micro-light source in a variety of sensor applications. 10 figs.

Micro optical fiber light source and sensor and method of fabrication thereof

DOEpatents

Kopelman, R.; Tan, W.; Shi, Z.Y.

1994-11-01

This invention relates generally to the development of and a method of fabricating a micro optical fiber light source. An optical fiber micro-light source is presented whose aperture is extremely small yet able to act as an intense light source. Light sources of this type have wide ranging applications, including use as micro-sensors in NSOM. Micro-sensor light sources have excellent detection limits as well as photo stability, reversibility, and millisecond response times. Furthermore, a method for manufacturing a micro optical fiber light source is provided. It involves the photo-chemical attachment of an optically active material onto the end surface of an optical fiber cable which has been pulled to form an end with an extremely narrow aperture. More specifically, photopolymerization has been applied as a means to photo-chemically attach an optically active material. This process allows significant control of the size of the micro light source. Furthermore, photo-chemically attaching an optically active material enables the implementation of the micro-light source in a variety of sensor applications. 4 figs.

Making Advanced Scientific Algorithms and Big Scientific Data Management More Accessible

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

Venkatakrishnan, S. V.; Mohan, K. Aditya; Beattie, Keith

2016-02-14

Synchrotrons such as the Advanced Light Source (ALS) at Lawrence Berkeley National Laboratory are known as user facilities. They are sources of extremely bright X-ray beams, and scientists come from all over the world to perform experiments that require these beams. As the complexity of experiments has increased, and the size and rates of data sets has exploded, managing, analyzing and presenting the data collected at synchrotrons has been an increasing challenge. The ALS has partnered with high performance computing, fast networking, and applied mathematics groups to create a"super-facility", giving users simultaneous access to the experimental, computational, and algorithmic resourcesmore » to overcome this challenge. This combination forms an efficient closed loop, where data despite its high rate and volume is transferred and processed, in many cases immediately and automatically, on appropriate compute resources, and results are extracted, visualized, and presented to users or to the experimental control system, both to provide immediate insight and to guide decisions about subsequent experiments during beam-time. In this paper, We will present work done on advanced tomographic reconstruction algorithms to support users of the 3D micron-scale imaging instrument (Beamline 8.3.2, hard X-ray micro-tomography).« less

EDITORIAL: LED light sources (light for the future) LED light sources (light for the future)

NASA Astrophysics Data System (ADS)

Grandjean, N.

2010-09-01

Generating white light from electricity with maximum efficacy has been a long quest since the first incandescent lamp was invented by Edison at the end of the 19th century. Nowadays, semiconductors are making reality the holy grail of converting electrons into photons with 100% efficiency and with colours that can be mixed for white light illumination. The revolution in solid-state lighting (SSL) dates to 1994 when Nakamura reported the first high-brightness blue LED based on GaN semiconductors. Then, white light was produced by simply combining a blue dye with a yellow phosphor. After more than a decade of intensive research the performance of white LEDs is quite impressive, beating by far the luminous efficacy of compact fluorescent lamps. We are likely close to replacing our current lighting devices by SSL lamps. However, there are still technological and fabrication cost issues that could delay large market penetration of white LEDs. Interestingly, SSL may create novel ways of using light that could potentially limit electricity saving. Whatever the impact of SSL, it will be significant on our daily life. The purpose of this special cluster issue is to produce a snapshot of the current situation of SSL from different viewing angles. In an introductory paper, Tsao and co-workers from Sandia National Laboratories, present an energy-economics perspective of SSL considering societal changes and SSL technology evolution. In a second article, Narukawa et al working at Nichia Corporation—the pioneer and still the leading company in SSL—describe the state of the art of current research products. They demonstrate record performance with white LEDs exhibiting luminous efficacy of 183 lm W-1 at high-current injection. Then, a series of topical papers discuss in detail various aspects of the physics and technology of white LEDs Carrier localization in InGaN quantum wells has been considered the key to white LEDs' success despite the huge density of defects. A comprehensive review of the different localization mechanisms and their implication for internal quantum efficiency (IQE) is proposed by Oliver and co-workers from Cambridge University. When discussing IQE in InGaN-based LEDs, the efficiency droop at high-current injection always emerges, which is a major concern for the future of SSL technology. Here, a collaborative work between Samsung and the Gwangju Institute of Science and Technology (Korea) proves that a specific design of the active region can limit this detrimental effect. Once the issue of the IQE is solved, one still has to let the photons out of the chip. Matioli and Weisbuch from the University of California at Santa Barbara introduce the use of photonic crystals (PhCs) to improve light extraction efficiency. They describe different approaches to overcoming the main limitation of LEDs when implementing surface PhCs. The technology of SSL, and in particular of colour rendering, is tackled by Zukauskas et al who studied in detail different white light sources. They show that extreme colour-fidelity indices need to cover the entire spectrum, with a broad-band at 530-610 nm and a component beyond 610 nm. Then, the reliability of GaN-based LEDs is discussed in the paper of Meneghesso and co-workers. The authors consider the most important physical mechanisms that are (i) the degradation of the active layer of LEDs, (ii) the degradation of the package/phosphor system, (iii) the failure of GaN-based LEDs against electrostatic discharge. Finally, GaN LEDs on silicon developed in the group of Egawa at the Nagoya Institute of Technology are presented. This technology could allow a significant decrease in the fabrication cost of white LEDs.

0.87-micron CSP diode lasers for spaceborne communications. [channeled-substrate-planar

NASA Technical Reports Server (NTRS)

Carlin, D. B.; Pultz, G. N.; Goldstein, B.

1987-01-01

Index-guided channeled-substrate-planar (CSP) AlGaAs diode lasers are being developed for reliable, high-power operation for use as sources in spaceborne optical communications systems. Although most work on this AlGaAs structure has been aimed at optimizing performance at output wavelengths less than 8400 A, emission in the 8700 A regime is also of interest. In particular, such wavelengths are required for use in the direct detection laser transceiver to be incorporated into NASA's advanced communications technology satellite, in order to avoid absorption of the light by the atmosphere when communicating with ground-based terminals. Lowest order spatial mode and substantially single longitudinal mode output has been observed in 0.87-micron CSP devices in excess of 50 mW cw and 100 mW 50 percent duty-cycle, with rms phase-front aberrations measured to be about lambda/40.

High resolution x-ray Thomson scattering measurements from cryogenic hydrogen jets using the linac coherent light source

DOE PAGES

Fletcher, L. B.; Zastrau, U.; Galtier, E.; ...

2016-08-15

Here, we present the first spectrally resolved measurements of x-rays scattered from cryogenic hydrogen jets in the single photon counting limit. The 120 Hz capabilities of the LCLS, together with a novel hydrogen jet design [J. B. Kim et al., Rev. Sci. Instrum. (these proceedings)], allow for the ability to record a near background free spectrum. Such high-dynamic-range x-ray scattering measurements enable a platform to study ultra-fast, laser-driven, heating dynamics of hydrogen plasmas. This measurement has been achieved using two highly annealed pyrolytic graphite crystal spectrometers to spectrally resolve 5.5 keV x-rays elastically and inelastically scattered from cryogenic hydrogen andmore » focused on Cornell-SLAC pixel array detectors [S. Herrmann et al., Nucl. Instrum. Methods Phys. Res., Sect. A 718, 550 (2013)].« less

An AlGaN Core-Shell Tunnel Junction Nanowire Light-Emitting Diode Operating in the Ultraviolet-C Band.

PubMed

Sadaf, S M; Zhao, S; Wu, Y; Ra, Y-H; Liu, X; Vanka, S; Mi, Z

2017-02-08

To date, semiconductor light emitting diodes (LEDs) operating in the deep ultraviolet (UV) spectral range exhibit very low efficiency due to the presence of large densities of defects and extremely inefficient p-type conduction of conventional AlGaN quantum well heterostructures. We have demonstrated that such critical issues can be potentially addressed by using nearly defect-free AlGaN tunnel junction core-shell nanowire heterostructures. The core-shell nanowire arrays exhibit high photoluminescence efficiency (∼80%) in the UV-C band at room temperature. With the incorporation of an epitaxial Al tunnel junction, the p-(Al)GaN contact-free nanowire deep UV LEDs showed nearly one order of magnitude reduction in the device resistance, compared to the conventional nanowire p-i-n device. The unpackaged Al tunnel junction deep UV LEDs exhibit an output power >8 mW and a peak external quantum efficiency ∼0.4%, which are nearly one to two orders of magnitude higher than previously reported AlGaN nanowire devices. Detailed studies further suggest that the maximum achievable efficiency is limited by electron overflow and poor light extraction efficiency due to the TM polarized emission.

On compensation in Si-doped AlN

NASA Astrophysics Data System (ADS)

Harris, Joshua S.; Baker, Jonathon N.; Gaddy, Benjamin E.; Bryan, Isaac; Bryan, Zachary; Mirrielees, Kelsey J.; Reddy, Pramod; Collazo, Ramón; Sitar, Zlatko; Irving, Douglas L.

2018-04-01

Controllable n-type doping over wide ranges of carrier concentrations in AlN, or Al-rich AlGaN, is critical to realizing next-generation applications in high-power electronics and deep UV light sources. Silicon is not a hydrogenic donor in AlN as it is in GaN; despite this, the carrier concentration should be controllable, albeit less efficiently, by increasing the donor concentration during growth. At low doping levels, an increase in the Si content leads to a commensurate increase in free electrons. Problematically, this trend does not persist to higher doping levels. In fact, a further increase in the Si concentration leads to a decrease in free electron concentration; this is commonly referred to as the compensation knee. While the nature of this decrease has been attributed to a variety of compensating defects, the mechanism and identity of the predominant defects associated with the knee have not been conclusively determined. Density functional theory calculations using hybrid exchange-correlation functionals have identified VAl+n SiAl complexes as central to mechanistically understanding compensation in the high Si limit in AlN, while secondary impurities and vacancies tend to dominate compensation in the low Si limit. The formation energies and optical signatures of these defects in AlN are calculated and utilized in a grand canonical charge balance solver to identify carrier concentrations as a function of Si content. The results were found to qualitatively reproduce the experimentally observed compensation knee. Furthermore, these calculations predict a shift in the optical emissions present in the high and low doping limits, which is confirmed with detailed photoluminescence measurements.

Prism-coupled light emission from tunnel junctions

NASA Technical Reports Server (NTRS)

Ushioda, S.; Rutledge, J. E.; Pierce, R. M.

1985-01-01

Completely p-polarized light emission has been observed from smooth Al-AlO(x)-Au tunnel junctions placed on a prism coupler. The angle and polarization dependence demonstrate unambiguously that the emitted light is radiated by the fast-mode surface plasmon polariton. The emission spectra suggest that the dominant process for the excitation of the fast mode is through conversion of the slow mode to the fast mode mediated by residual roughness on the junction surface.

Mapping Pluto's Temperature Distribution Through Twenty Years of Stellar Occultations

NASA Astrophysics Data System (ADS)

Zangari, Amanda; Binzel, R. P.; Person, M. J.

2012-10-01

Multi-chord, high signal-to-noise Pluto occultations have been observed several times over the past two decades, including events in 1988, 2002, 2006, 2007, 2010 and 2011 (Elliot et al. 1989, 2003, 2007; Person et al. 2008, 2010, 2011). We fit separate immersion and emersion occultation light-curve models to each of the individual light curves obtained from these efforts. Asymmetries in the light curves result in the half-light temperatures for opposite sides of a single chord to differ by up to 20 Kelvin in the largest case. The temperature difference for each chord is consistent using both isothermal (b=0) and non-isothermal (e.g. b=-2.2) models based on the methodology described by Elliot & Young (1992). We examine the relationship between the location of immersion and emersion points on Pluto and these temperatures at the half-light radius and will present results for correlations between these location/temperature data and surface composition maps, Pluto geometry, and accumulated insolation patterns. This work was supported by NASA Planetary Astronomy Grant to MIT (NNX10AB27G), and NSF Astronomy and Astrophysics Grant to MIT (0707609). The authors would like to acknowledge the late Professor James L. Elliot for his efforts in beginning this work. References: Elliot, J. L., Dunham, E. W., Bosh, A. S., et al. 1989, Icarus, 77,148 Elliot, J. L., Ates, A., Babcock, B. A., et al. 2003, Nature, 424,165 Elliot, J. L., Person, M. J., Gulbis, A. A. S., et al. 2007, AJ, 134, 1 Elliot, J. L., & Young, L. A. 1992, AJ, 103, 991. Person, M. J., Elliot, J. L., Gulbis, A. A. S., et al. 2008, AJ, 136, 1510 Person, M. J., Elliot, J. L., Bosh, A. S., et al. 2010, Bulletin of the American Astronomical Society, 42, 983 Person, M. J., Dunham, E. W., Bida, T., et al. 2011, EPSC-DPS Joint Meeting 2011, 1374.

Room-temperature continuous-wave electrically injected InGaN-based laser directly grown on Si

NASA Astrophysics Data System (ADS)

Sun, Yi; Zhou, Kun; Sun, Qian; Liu, Jianping; Feng, Meixin; Li, Zengcheng; Zhou, Yu; Zhang, Liqun; Li, Deyao; Zhang, Shuming; Ikeda, Masao; Liu, Sheng; Yang, Hui

2016-09-01

Silicon photonics would greatly benefit from efficient, visible on-chip light sources that are electrically driven at room temperature. To fully utilize the benefits of large-scale, low-cost manufacturing foundries, it is highly desirable to grow direct bandgap III-V semiconductor lasers directly on Si. Here, we report the demonstration of a blue-violet (413 nm) InGaN-based laser diode grown directly on Si that operates under continuous-wave current injection at room temperature, with a threshold current density of 4.7 kA cm-2. The heteroepitaxial growth of GaN on Si is confronted with a large mismatch in both the lattice constant and the coefficient of thermal expansion, often resulting in a high density of defects and even microcrack networks. By inserting an Al-composition step-graded AlN/AlGaN multilayer buffer between the Si and GaN, we have not only successfully eliminated crack formation, but also effectively reduced the dislocation density. The result is the realization of a blue-violet InGaN-based laser on Si.

Degradation Mechanisms for GaN and GaAs High Speed Transistors

PubMed Central

Cheney, David J.; Douglas, Erica A.; Liu, Lu; Lo, Chien-Fong; Gila, Brent P.; Ren, Fan; Pearton, Stephen J.

2012-01-01

We present a review of reliability issues in AlGaN/GaN and AlGaAs/GaAs high electron mobility transistors (HEMTs) as well as Heterojunction Bipolar Transistors (HBTs) in the AlGaAs/GaAs materials systems. Because of the complex nature and multi-faceted operation modes of these devices, reliability studies must go beyond the typical Arrhenius accelerated life tests. We review the electric field driven degradation in devices with different gate metallization, device dimensions, electric field mitigation techniques (such as source field plate), and the effect of device fabrication processes for both DC and RF stress conditions. We summarize the degradation mechanisms that limit the lifetime of these devices. A variety of contact and surface degradation mechanisms have been reported, but differ in the two device technologies: For HEMTs, the layers are thin and relatively lightly doped compared to HBT structures and there is a metal Schottky gate that is directly on the semiconductor. By contrast, the HBT relies on pn junctions for current modulation and has only Ohmic contacts. This leads to different degradation mechanisms for the two types of devices.

Kinetic modeling of x-ray laser-driven solid Al plasmas via particle-in-cell simulation

NASA Astrophysics Data System (ADS)

Royle, R.; Sentoku, Y.; Mancini, R. C.; Paraschiv, I.; Johzaki, T.

2017-06-01

Solid-density plasmas driven by intense x-ray free-electron laser (XFEL) radiation are seeded by sources of nonthermal photoelectrons and Auger electrons that ionize and heat the target via collisions. Simulation codes that are commonly used to model such plasmas, such as collisional-radiative (CR) codes, typically assume a Maxwellian distribution and thus instantaneous thermalization of the source electrons. In this study, we present a detailed description and initial applications of a collisional particle-in-cell code, picls, that has been extended with a self-consistent radiation transport model and Monte Carlo models for photoionization and K L L Auger ionization, enabling the fully kinetic simulation of XFEL-driven plasmas. The code is used to simulate two experiments previously performed at the Linac Coherent Light Source investigating XFEL-driven solid-density Al plasmas. It is shown that picls-simulated pulse transmissions using the Ecker-Kröll continuum-lowering model agree much better with measurements than do simulations using the Stewart-Pyatt model. Good quantitative agreement is also found between the time-dependent picls results and those of analogous simulations by the CR code scfly, which was used in the analysis of the experiments to accurately reproduce the observed K α emissions and pulse transmissions. Finally, it is shown that the effects of the nonthermal electrons are negligible for the conditions of the particular experiments under investigation.

LED intense headband light source for fingerprint analysis

DOEpatents

Villa-Aleman, Eliel

2005-03-08

A portable, lightweight and high-intensity light source for detecting and analyzing fingerprints during field investigation. On-site field analysis requires long hours of mobile analysis. In one embodiment, the present invention comprises a plurality of light emitting diodes; a power source; and a personal attachment means; wherein the light emitting diodes are powered by the power source, and wherein the power source and the light emitting diodes are attached to the personal attachment means to produce a personal light source for on-site analysis of latent fingerprints. The present invention is available for other applications as well.

Quantifying Source Sector and Region Contributions of BC and Dust Deposition on the Arctic Snow and the Resulting Albedo Reduction

NASA Astrophysics Data System (ADS)

Sobhani, N.; Gregory, C.; Kulkarni, S.

2017-12-01

Long-range transport of atmospheric particulate matter (PM) from mid-latitude sources to the Arctic is the main contributor to the Arctic PM loadings and deposition. Light absorbing particles such as Black Carbon (BC) and dust are considered of great climatic importance and are the main absorbers of sunlight in the atmosphere. Wet and dry deposition of light absorbing particles (LAPs) on snow and ice cause reduction of snow and ice albedo. LAPs have significant radiative forcing and effect on snow albedo causing snow and ice to warm and melt more quickly. There are large uncertainties in estimating radiative forcing of LAPs. In this study, the potential impacts of LAPs from different emission source regions and sectors on snow albedo in the Arctic are studied. A modeling framework including Weather Research and Forecasting Model (WRF) and the University of Iowa's Sulfur Transport and dEpostion model (STEM) is used to simulate the seasonality and transport of LAPs from different geographical sources and sectors (i.e. transportation, residential, industry, biomass burning and power) to the Arctic. The main geographical source contributor to the Arctic BC annual deposition flux is China. However, there is a distinct seasonal variation for the contributions of geographical source emissions to BC deposition. During the spring, when the deposition flux is highest, the contribution of biomass burning attributes for up to 40% of total deposition at Alert and Barrow. However, during the winter, the anthropogenic sectors contribute up to 95% of total BC deposition. The simulated snow BC mixing ratios are evaluated using the observed BC snow concentration values from previous studies including Doherty et al., 2010. The simulations show the BC deposition causes 0.6% snow albedo decrease during spring 2008 over the Arctic.

VizieR Online Data Catalog: Spitzer photometry of globulars in 2 galaxies (Spitler+, 2008)

NASA Astrophysics Data System (ADS)

Spitler, L. R.; Forbes, D. A.; Beasley, M. A.

2010-06-01

Catalogues are described in Spitler et al. (2008MNRAS.389.1150S) All photometry is corrected for Galactic dust extinction and are on the Vega photometric system. NGC 5128 optical photometry is from Peng et al. (2004ApJS..150..367P), as compiled in Woodley et al. (2007AJ....134..494W). Globular cluster identification numbers are from Woodley et al. (2007, Cat. J/AJ/134/494). NGC 4594 optical photometry is from Spitler et al. (2006AJ....132.1593S) updated with new aperture corrections as described in Harris et al. (2010MNRAS.401.1965H). Identification number, globular cluster half-light radii and the assumed distance modulus for the half-light radii are from Spitler et al. (2006, Cat. J/AJ/132/1593). A ultra-compact dwarf galaxy is included in this catalogue with ID="ucd" (see also Hau et al. 2009MNRAS.394L..97H). (2 data files).

Tertiary particle physics with ELI: from challenge to chance (Conference Presentation)

NASA Astrophysics Data System (ADS)

Drska, Ladislav

2017-05-01

nteraction of high-intensity laser pulses with solid state targets results in generation of intense pulses of secondary particles via electromagnetic interaction : electrons, ions, hard x-rays. The beams of these particles can be used to produce various types of third-generation particles, beyond electromagnetic also other types of fundamental interactions can be involved in this process [1]. As the most interesting tertiary particles could be mentioned positrons, neutron, muons. This paper shall extend our previous analysis of this topic [2]: it discusses selected technical problems of design and realization of applicable sources of these particles and presents some more elaborated proposals for potential meaningful / hopefuly realistic exploitations of this technology. (1)Tertiary Sources (TS) : First Development Steps. This part of the presentation includes the topics as follows: (11) Pulsed positron sources: Verified solutions of laser-driven positron sources [3] [4] [5], development towards applicable facilities. Some unconventional concepts of application of lasers for positron production [6]. Techniques for realization of low/very-low energy positrons. (12) Taylored neutron sources [7]: Neutron sources with demanded space distribution, strongly beamed and isotropic solutions [8] [9]. Neutron generation with taylored energy distribution. Problem of the direct production of neutrons with very low energy [10] [11]. (13) Potential muon sources: Proof-of-principle laser experiment on electron / photon driven muon production [12] [13]. Study of the possibility of effective generation of surface muons. Problems of the production of muons with very low energy. (2) Fundamental & Applied Physics with TS: This part of the talk presents the themes: (21) Diagnostic potential of TS: Lepton emission as a signature of processes in extreme systems. Passive and active diagnostics using positrons, problems of detection and evaluation. Potential diagnostic applications of muons. Concrete application study: muon tomography. (22) Antilepton gravity studies [14]: Possibility of antimattter gravity research using positronium and muonium [15] [16]. Lepton / antilepton gravity studiesactive with relativistic particle beams [17]. First-phase practical application : positron production for filling (commertial) particle traps, development base for multiple microtrap systems. (23) Hidden world searching [18] : Potential laser-based production / detection of selected dark mattter particles - axions, hidden photons [19] [20]. Search for hidden particles in nuclear decay processes [21]. Potential application output: intense positronium source. Conclusion: The extensive feasibility study confirms the potential of ELI to contribute to the solution of Grand Challenge Problems of physics. Laser-produced tertiary particles will play important role in this effort. : References [1] L.Drska et al.: Physics of Extreme Systems. Course ATHENS CTU18, Prague 12 - 19 Nov., 2016. http://vega.fjfi.cvut.cz/docs/athens2016/ [2] L.Drska : Lepton Diagnostics and Antimatter Physics. In: SPIE Optics+Optoelectronics, Prague, April 13 - 16, 2015 . [3] H. Chen et al.: Scaling the Yield of Laser-Driven Electron-Positron Jets to Laboratory Astrophysics Applications. Rep. LLNL-JRNL-665381, Dec. 11, 2014. [4] E Liang et al.: High e+ / e- Ratio Dense Pair Creation with 1022 W.cm-2 Laser Irradiating Solid Targets. Scientific Reports, Sept. 14, 2015. www.nature.com/scientificreports [5] G. Sarri et al.: Spectral and Spatial Characterization of Laser-driven Positron Beams. Plasma Phys. Control. Fusion 59 (2017) 014015. [6] B. Schoch: A Method to Produce Intense Positron Beams via Electro Pair Production on Electrons. arXiv:1607.03847v1 [physics.acc-ph] [7] I. Pomerantz: Laser Generation of Neutrons: Science and Applications. In: ELI-NP Summer School, Magurele, Sept. 21 - 25, 2015. http://www.eli-np.ro/2015-summer-school/presentations/23.09/Pomerantz_Eli-NP-Summer-school-2015.pdf [8] V.P. Kovalev: Secondary Radiation of Electron Accelerators (in Russian). Atomizdat 1969. [9] M. Lebois et al.: Development of a Kinematically Focused Neutron Source with p(Li7,n)Be7 Inverse Reaction. Nucl. Instr. Meth. Phys. Res. A 735 (2014), 145. [10] D. Habs et al.: Neutron Halo Isomers in Stable Nuclei and their Possible Application for the Production of Low Energy, Pulsed, Polarized Neutron Beams of High Intensity and High Brilliance. Appl. Phys B103 (2011),485. [11] T. Masuda et al.: A New Method of Creating High/Intensity Neutron Source. arXiv:1604.02818v1[nucl-ex] [12] A.I. Titov et al.: Dimuon Production by Laser-wakefield Accelerated Electrons. Phys. Rev. ST Accel. Beams 12 (2009) 111301. [13] W. Dreesen et al.: Detection of Petawatt Laser-Induced Muon Source for Rapid High-Gamma Material Detection. DOE/NV/25946-2262. [14] F. Castelli: Positronium and Fundamental Physics: What Next ? In: What Next, Florence 2015. [15] G. Dufour et al. : Prospects for Studies of the Free Fall and Gravitation Quantum States of Antimatter. Advances in High Energy Physics 2015 (2015) 379642. [16] D.M. Kaplan et al.. Antimatter Gravity with Muonium. IIT-CAPP-16-1. arXiv:1601.07222v2 [physics.ins-det] [17] T. Kalaydzhyan: Gravitational Mass of Positron from LEP Synchrotron Losses. arXiv:1508.04377v3 [hep-ph] [18] J. Alexander et al.: Dark Sector 2016 Workshop: Community Report. arXiv:1608.08632[hep-ph] [19] M.A. Wahud et al.: Axion-like Particle Production in a Laser-Induced Dynamical Spacertime. arXiv:1612.07743v1 [hep-ph] [20] V. Kozhuharov et al: New Projects on Dark Photon Search. arXiv:1610.04389v1 [hep-ex] [21] A.J. Krasznahorkay et al.: Observation of Anomalous Internal Pair Creation in Be8: A Possible Signature of a Light, Neutral Boson. arXiv:1504.01527v1 [nucl-ex

Possible Role of Hydrogen in the Earth Core

NASA Astrophysics Data System (ADS)

Takahashi, E.; Imai, T.

2011-12-01

Possible role of hydrogen in the Earth core has been discussed by Stevenson (1977) and demonstrated experimentally by Fukai (1984), Okuchi (1997) and others. Planetary theory proposes a possibility of hydrogen incorporation in Earth's magma ocean from ambient solar nebula gas (Ikoma & Genda 2005, Genda & Ikoma 2008). More recently, migration of snow line during planet formation was examined (Min et al., 2010; Oka et al, 2011) and it was proposed that the Earth building material originally contained abundant water as ice and hydrous minerals. Therefore, it is very important to investigate the fate of water in the planet building process and clarify the role of hydrogen in the planetary core. Using SPring-8 synchrotron (NaCl capsule, LiAlH4 as hydrogen source), we determined the melting curve of FeH up to 20 GPa under hydrogen saturated conditions (Sakamaki, Takahashi et al, 2009). Observed melting point is below 1300C and has a very small dT/dP slope. By extrapolating the melting curve using Lindeman's law, we proposed that hydrogen could lower the melting temperature of the Earth core by more than 1500K than current estimate. Here we report our new experiments using SPring-8 synchrotron (single crystal diamond capsule, water as hydrogen source). Hydrogen concentration and melting temperature of FeHx that coexists with hydrous mantle minerals were determined at 15-20GPa and 1000-1600C. We show that 1) hydrogen concentration in FeHx at 1000C, coexisting with hydrous-B and ringwoodite is approximately X=0.6. 2) Upon heating, hydrous-B decomposes and hydrogen strongly partitions into FeHx (X=0.8~1.0) than ringwoodite. 3) FeHx that coexists with ringwoodite melts between ~1300C (solidus) and ~1600C (liquidus). Combined our new experiments with those by Sakamaki et al (2009) and Shibazaki et al (2009), partitioning of hydrogen between proto-core and primitive mantle is discussed. We propose that >90% of water in the source material may have entered the Earth core. Given large hydrogen concentration in the Earth core, temperature of the outermost core could be as low as that of lower mantle adiabat. Presence of the light element-rich layer at the top 300km layer of the outer core (Helffrich & Kaneshima, 2010) may be easily understood if there is no temperature gap between the core and the lower mantle.

Al x Ga1‑ x N-based semipolar deep ultraviolet light-emitting diodes

NASA Astrophysics Data System (ADS)

Akaike, Ryota; Ichikawa, Shuhei; Funato, Mitsuru; Kawakami, Yoichi

2018-06-01

Deep ultraviolet (UV) emission from Al x Ga1‑ x N-based light-emitting diodes (LEDs) fabricated on semipolar (1\\bar{1}02) (r-plane) AlN substrates is presented. The growth conditions are optimized. A high NH3 flow rate during metalorganic vapor phase epitaxy yields atomically flat Al y Ga1‑ y N (y > x) on which Al x Ga1‑ x N/Al y Ga1‑ y N multiple quantum wells with abrupt interfaces and good periodicity are fabricated. The fabricated r-Al x Ga1‑ x N-based LED emits at 270 nm, which is in the germicidal wavelength range. Additionally, the emission line width is narrow, and the peak wavelength is stable against the injection current, so the semipolar LED shows promise as a UV emitter.

Al decorated ZnO thin-film photoanode for SPR-enhanced photoelectrochemical water splitting

NASA Astrophysics Data System (ADS)

Li, Hongxia; Li, Xin; Dong, Wei; Xi, Junhua; Wu, Xin

2018-06-01

Photoelectrochemical (PEC) water splitting has been considered to be a promising approach to ease the energy and environmental crisis. Herein, Al decorated ZnO thin films are successfully achieved through a facile dc magnetron-sputtering method followed with Al evaporation for further enhanced PEC performance. The Al/ZnO thin film with 60 s Al evaporating time exhibits the highest photocurrent density under AM1.5G and visible light irradiation, which are more than 5 and 3 times as the pure ZnO film, respectively. Such surface modification by Al not only enlarges the visible light absorption based on surface plasmonic resonance effect, but facilitates the charge separation and transportation at the electrode/electrolyte interface. Finally, a possible mechanism is proposed for the photocatalytic activity enhancement of Al/ZnO thin film photoanode.

Photosensitivity enhancement of PLZT ceramics by positive ion implantation

DOEpatents

Land, Cecil E.; Peercy, Paul S.

1983-01-01

The photosensitivity of lead lanthanum zirconate titanate (PLZT) ceramic material used in high resolution, high contrast, and non-volatile photoferroelectric image storage and display devices is enhanced significantly by positive ion implantation of the PLZT near its surface. Implanted ions include H.sup.+, He.sup.+, Ne.sup.+, Ar.sup.+, as well as chemically reactive ions from Fe, Cr, and Al. The positive ion implantation advantageously serves to shift the absorption characteristics of the PLZT material from near-UV light to visible light. As a result, photosensitivity enhancement is such that the positive ion implanted PLZT plate is sensitive even to sunlight and conventional room lighting, such as fluorescent and incandescent light sources. The method disclosed includes exposing the PLZT plate to the positive ions at sufficient density, from 1.times.10.sup.12 to 1.times.10.sup.17, and with sufficient energy, from 100 to 500 KeV, to provide photosensitivity enhancement. The PLZT material may have a lanthanum content ranging from 5 to 10%, a lead zirconate content of 62 to 70 mole %, and a lead titanate content of 38 to 30%. The ions are implanted at a depth of 0.1 to 2 microns below the surface of the PLZT plate.

Effect of grain size on optical transmittance of birefringent polycrystalline ceramics

NASA Astrophysics Data System (ADS)

Wen, Tzu-Chien

Polycrystalline ceramics are increasingly used for fabricating windows and domes for the mid infra-red regime (3-5 mum) due to their superior durability as compared to glass and the lower cost of their fabrication and finishing relative to single crystals without significant compromise in optical properties. Due to the noncubic structure, MgF2 and Al2O3 are birefringent ceramics. Birefringence causes scatter of light at the grain boundaries and diminishes in-line transmittance and optical performance. This dissertation presents experimental results and analyses of the grain-size and wavelength dependence of the in-line transmittance of polycrystalline MgF2 and Al2O3. Chapter 2 presents experimental results and analyses of light transmission in polycrystalline MgF2 as a function of the mean grain size at different wavelengths. The scattering coefficient of polycrystalline MgF 2 increased linearly with the mean grain size and inversely with the square of the wavelength of light. These trends are consistent with theoretical models based on both a limiting form of the Raleigh-Gans-Debye theory of particle scattering and light retardation theories that take refractive-index variations along the light path. Chapter 3 investigates the applicability of particle light scattering theories to light attenuation in birefringent polycrystalline ceramics by measuring light transmittance in a model two-phase system. The system consisted of microspheres of silica dispersed in a solution of glycerol in water. It was found that RGD theory showed the systematic deviation for higher particle volume fraction (φ > 0.2) and larger particle size (d p > 1 mum). This result suggested that light scattering models based on single particle scattering are unlikely to provide viable physical explanation for the effect of grain size on light transmittance in birefringent polycrystalline ceramics due to the high volume fraction in dense polycrystalline ceramics. Chapter 4 analyses light transmission properties of polycrystalline Al 2O3 using theories of wave propagation in random media. Fully dense polycrystalline Al2O3 was fabricated using a pressure filtration method. By obtaining the Delta n2 measured from EBSD, the wave retardation theories of Raman and Viswanathan and Kahan et al. provided upper and lower bounds for the theoretical predictions of light transmittance as a function of mean intercept length.

Fabrication of ZnAl mixed metal-oxides/RGO nanohybrid composites with enhanced photocatalytic activity under visible light

NASA Astrophysics Data System (ADS)

Ni, Jie; Xue, Jinjuan; Shen, Jing; He, Guangyu; Chen, Haiqun

2018-05-01

The ZnAl mixed metal-oxides (MMOs)/graphene nanocomposites were successfully fabricated by a facile hydrothermal method combined with a calcination process. The thermal treatment enables simultaneously the formation of ZnO/ZnAl2O4 heterogeneous structure, which are uniformly decorated on the surface of graphene, accompanying with the reduction of graphene oxide. The as-prepared heterostructure photocatalysts were well characterized by powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and UV-vis diffuse reflectance spectroscopy (DRS) to conduct investigations into the phase structures, microstructure and optical capability. The ZnAl MMO/RGO20 composite displayed favorable adsorption property and photo-degradation efficiency for Ciprofloxacin (CIP) aqueous solution under visible light. The photo-degradation efficiency of the as-prepared ZnAl MMO/RGO20 was 3.0 and even 4.6 times higher than that of ZnAl MMO and pure ZnAl LDH, respectively. The improvement of photocatalytic performance is ascribed to the synergistic effect of heterogeneous structure coupled with graphene, which realizes efficient charge separation efficiency, enlarged visible light adsorption range, and chemical stability of hybrid nanocomposite. The results of EIS, PL and photocurrent response also explained the best performance of ZnAl MMO/RGO20 nanocomposite. Besides, the mechanism of ZnAl MMO/RGO20 photocatalytic system was proposed and analyzed in detail.

Atomic-Scale Structure of the Tin DX Center and Other Related Defects in Aluminum Gallium Arsenide Semiconductors Using Moessbauer Spectroscopy.

NASA Astrophysics Data System (ADS)

Greco, Luigi Alessandro

The DX center in III-V alloys has limited the use of these materials for electronic devices since the defect acts as an electron trap. To be able to control or eliminate the DX center, its atomic scale structure should be understood. Mossbauer spectroscopy has proven to be a valuable technique in probing the atomic-scale structure of certain atomic species. The dopant studied here is ^{119}Sn. The thermal diffusion of Sn in Al_ {rm x}Ga_{rm 1-x }As using different temperatures, times, sample geometries and As_4 overpressures in evacuated and sealed fused silica ampoules was studied by x-ray diffraction (XRD), secondary ion mass spectroscopy and electrochemical capacitance versus voltage measurements. The AlGaAs surfaces decomposed into various Sn, Si, Ga and As oxides when an As_4 overpressure was introduced during annealing. However, annealing under ambient As_4 and furnace cooling eliminated surface decomposition although the Sn diffusion depth was less than that for a 0.5 atm As_4 overpressure. SiO_{rm x} and Si_{rm x }N_{rm y} RF-sputtered thin film capping layers deposited on AlGaAs were studied by XRD and Auger electron spectroscopy. For the annealed SiO_{rm x} films the AlGaAs surface was preserved, independent of the cooling technique used. Mossbauer spectroscopy was conducted on ^{rm 119m} Sn-implanted Al_ {rm x } Ga_{rm 1-x} As (x = 0.22 and 0.25) used for the source experiments and ^{119}Sn-doped Al _{rm x}Ga _{rm 1-x}As (x = 0.15, N _{rm Sn} ~2 times 10 ^{18} cm^{ -3}) for the absorber experiment. The source samples were capped with 120 nm of SiO_ {rm x} to preserve the surface during the systematic study of annealing temperature versus site occupation and electrical activation via Mossbauer spectroscopy at 76 K and 4 K in the dark and in the light (to observe persistent photoconductivity (PPC) due to the DX center). For all of the annealing conditions used the x = 0.22 sample showed little evidence of PPC possibly due to compensating defects and/or radiation-induced capture. After annealing the x = 0.25 sample at 1000^circC for 2 hours under a Ga + Al overpressure, evidence of PPC was found via Hall measurements but no effect was seen by Mossbauer suggesting radiation-induced capture and/or non-nearest-neighbor lattice relaxation. The Ga + Al overpressure also served to decrease the loss of Sn through the SiO _{rm x} film, possibly through the removal of Ga and Al vacancies. The x = 0.15 absorber showed a persistent 15-18% change in the electrical resistance (10% change in n) between the light and dark. However, the observation of this effect was not apparent, even assuming negative-U (2 electron) behavior, in the Mossbauer measurements. This was also consistent with EXAFS results. These studies do not support the broken-bond model of Chadi and Chang, which is considered to be a widely accepted atomic-scale model of the DX center. A defect complex consisting of a substitutional Sn_{rm Ga(Al) }^+ site, and a (V_{ rm III}^-Al_{ rm As}^{-2}) complex, which localizes 3 electrons and may not be a nearest-neighbor to the donor, was chosen for the DX center in the x = 0.15 sample which supports EXAFS, recent positron annihilation and these Mossbauer studies.

A novel yellow-emitting SrAlSi4N7:Ce3+ phosphor for solid state lighting: Synthesis, electronic structure and photoluminescence properties

NASA Astrophysics Data System (ADS)

Ruan, Jian; Xie, Rong-Jun; Funahashi, Shiro; Tanaka, Yoshinori; Takeda, Takashi; Suehiro, Takayuki; Hirosaki, Naoto; Li, Yuan-Qiang

2013-12-01

Ce3+-doped and Ce3+/Li+-codoped SrAlSi4N7 phosphors were synthesized by gas pressure sintering of powder mixtures of Sr3N2, AlN, α-Si3N4, CeN and Li3N. The phase purity, electronic crystal structure, photoluminescence properties of SrAlSi4N7:Ce3+(Ce3+/Li+) were investigated in this work. The band structure calculated by the DMol3 code shows that SrAlSi4N7 has a direct band gap of 3.87 eV. The single crystal analysis of Ce3+-doped SrAlSi4N7 indicates a disordered Si/Al distribution and nitrogen vacnacy defects. SrAlSi4N7 was identified as a major phase of the fired powders, and Sr5Al5Si21N35O2 and AlN as minor phases. Both Ce3+ and Ce3+/Li+ doped SrAlSi4N7 phosphors can be efficiently excited by near-UV or blue light and show a broadband yellow emission peaking around 565 nm. A highest external quantum efficiency of 38.3% under the 450 nm excitation was observed for the Ce3+/Li+-doped SrAlSi4N7 (5 mol%). A white light LED lamp with color temperature of 6300 K and color rendering index of Ra=78 was achieved by combining Sr0.97Al1.03Si3.997N\\94\\maccounttest14=t0005_18193 7:Ce3+0.03 with a commercial blue InGaN chip. It indicates that SrAlSi4N7:Ce3+ is a promising yellow emitting down-conversion phosphor for white LEDs.

Light responses in Photoperiodism in Arabidopsis thaliana

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

Anthony R. Cashmore

2006-08-01

ADO1: An Arabidopsis blue light photoreceptor We have reported the characterization of an Arabidopsis gene encoding the ADAGIO 1 (ADO1) protein (Jarillo et al., 2001a). ADO1 contains a LOV domain, similar to WHITE COLLAR 1 (WC1), a photoreceptor for entrainment of Neurospora circadian rhythms (Froehlich et al., 2002), as well as PHOT1 and PHOT2, the blue light photoreceptors for phototropism (Briggs et al., 2001; Christie et al., 1998; Jarillo et al., 2001b; Kinoshita et al., 2001). Loss of function ado1 mutants show an unusually long periodicity for their free running circadian rhythm (Jarillo et al., 2001a). This observation holds formore » plants grown under white light as well as blue light and surprisingly, plants grown under red light also show altered circadian properties. The similarity of the LOV domain of ADO1 to those of PHOT1, PHOT2 and WC1 (known flavoprotein photoreceptors) as well as the genetic and molecular properties of ADO1, indicate that ADO1 is likely a new class of blue light photoreceptor. Indeed, the LOV domain of the related FKF1/ADO3 has been shown to bind FMN, and exhibit the in vitro photochemistry characteristic of PHOT1 (Imaizumi et al., 2003). Furthermore, ZTL/ADO1 has been shown to participate in the circadian and proteasome mediated degradation of the Arabidopsis clock protein, TOC1 (Mas et al., 2003). We also showed that the ado1 mutation selectively confers hypersensitivity to red light — when grown under red light (but not blue light) the ado1 mutant possesses an unusually short hypocotyl. This red light hypersensivity is even more severe in a triple ado1 ado2 ado3 mutant — ADO2 and ADO3 being the two other members of this ADAGIO gene family. This finding of a mutant phenotype under red light is somewhat unexpected for a protein thought to function as a photoreceptor for blue light. We have pursued our studies of ADO1 by preparing a mutant gene for which we have altered the codon for the cysteine residue conserved in all LOV domains. It is this cysteine residue that forms a covalent adduct with the bound flavin in the photocycle of PHOT1 and FKF1. In the mutant ADO1 this cysteine is replaced by an alanine. We argue that if ADO1 functions as a photoreceptor in a similar fashion to PHOT1, then this mutant ADO1 should not be able to rescue the altered circadian phenotype of ado1 mutant plants. We find under white light, that indeed this is the case. Experiments underway are aimed at determining if the altered circadian phenotype under blue and red light are similarly unable to be rescued by the mutant gene, and we are performing similar experiments under red light with respect to the defect in hypocotyl elongation. The results from these experiments will likely support the hypothesis that ADO1 functions as a blue light photoreceptor, and they will address the question concerning whether or not the altered properties of the ado1 mutant under red light are also a reflection of this photoreceptor function. References. Briggs, W. R., Beck, C. F., Cashmore, A. R., Christie, J. M., Hughes, J., Jarillo, J. A., Kagawa, T., Kanegae, H., Liscum, E., Nagatani, A., et al. (2001). The phototropin family of photoreceptors. Plant Cell 13, 993-997. Christie, J. M., Reymond, P., Powell, G. K., Bernasconi, P., Raibekas, A. A., Liscum, E., and Briggs, W. R. (1998). Arabidopsis NPH1: A flavoprotein with the properties of a photoreceptor for phototropism. Science 282, 1698-1701. Froehlich, A. C., Liu, Y., Loros, J. J., and Dunlap, J. C. (2002). White Collar-1, a circadian blue light photoreceptor, binding to the frequency promoter. Science 297, 815-819. Imaizumi, T., Tran, H. G., Swartz, T. E., Briggs, W. R., and Kay, S. A. (2003). FKF1 is essential for photoperiodic-specific light signalling in Arabidopsis. Nature 426, 302-306. Jarillo, J. A., Capel, J., Tang, R.-H., Yang, H.-Q., Alonso, J. M., Ecker, J. R., and Cashmore, A. R. (2001a). An Arabidopsis circadian clock component interacts with both CRY1 and phyB. Nature 410, 487-490. Jarillo, J. A., Gabrys, H., Capel, J., Alonso, J. M., Ecker, J. R., and Cashmore, A. R. (2001b). Phototropin-related NPL1 controls chloroplast relocation induced by blue light. Nature 410, 952-954. Kinoshita, T., Doi, M., Suetsugu, N., Kagawa, T., Wada, M., and Shimazaki Ki, K. (2001). phot1 and phot2 mediate blue light regulation of stomatal opening. Nature 414, 656-660. Mas, P., Kim, W. Y., Somers, D. E., and Kay, S. A. (2003). Targeted degradation of TOC1 by ZTL modulates circadian function in Arabidopsis thaliana. Nature 426, 567-570.« less

Spectral design flexibility of LED brings better life

NASA Astrophysics Data System (ADS)

Ou, Haiyan; Corell, Dennis; Ou, Yiyu; Poulsen, Peter B.; Dam-Hansen, Carsten; Petersen, Paul-Michael

2012-03-01

Light-emitting diodes (LEDs) are penetrating into the huge market of general lighting because they are energy saving and environmentally friendly. The big advantage of LED light sources, compared to traditional incandescent lamps and fluorescent light tubes, is the flexible spectral design to make white light using different color mixing schemes. The spectral design flexibility of white LED light sources will promote them for novel applications to improve the life quality of human beings. As an initial exploration to make use of the spectral design flexibility, we present an example: 'no blue' white LED light source for sufferers of disease Porphyria. An LED light source prototype, made of high brightness commercial LEDs applying an optical filter, was tested by a patient suffering from Porphyria. Preliminary results have shown that the sufferer could withstand the light source for much longer time than the standard light source. At last future perspectives on spectral design flexibility of LED light sources improving human being's life will be discussed, with focus on the light and health. The good health is ensured by the spectrum optimized so that vital hormones (melatonin and serotonin) are produced during times when they support human daily rhythm.

Sedimentary input into the source of Martinique lavas: a Li perspective

NASA Astrophysics Data System (ADS)

Tang, M.; Chauvel, C.; Rudnick, R. L.

2013-12-01

The Lesser Antilles arc is known for the prominent continental crustal signatures in its lavas. It thus provides an ideal target for studying crustal recycling in subduction zones. Martinique Island, located in the middle of the Lesser Antilles arc, has been well characterized for its elemental and radiogenic isotope geochemistry (Labanieh et al., 2012). We measured Li isotopes in the Martinique lavas as well as sediments cored at the southern (Site 144) and northern part (Site 543) of the subducting slab. The sediments show a large isotopic variation (δ7Li ~ -4.2‰ to +3.2‰) but the average δ7Li of -1.1 × 2.4‰ (1 σ, n = 15) is significantly lower than that of N-MORB (δ7Li = + 3.4 × 0.7‰, 1 σ, Tomascak et al., 2008), reflecting the influence of chemical weathering in the continental provenance. Although the subducting sediments display marked mineralogical and chemical shifts from south to north due to different deposition distances to the continental platform (Carpentier et al., 2009), their average Li isotopic compositions are indiscernible from each other. With a few exceptions, the Li isotopic compositions of the Martinique lavas are systematically lighter than MORB, giving an average δ7Li of 1.6 × 1.4‰ (1 σ, n = 25, 4 exceptions excluded). The δ7Li values show no correlation with any radiogenic isotope ratios (206Pb/204Pb, 87Sr/86Sr, 143Nd/144Nd and 176Hf/177Hf), Li/Y ratio, La/Sm ratio and SiO2 content. Therefore, the light Li isotopic composition likely reflects the source characteristics rather than contamination within the arc crust. Incorporation of the isotopically light sediments from Site 144 and 543 in the source may explain the depletion of 7Li in the Martinique lavas. A two-end-member mixing model requires 2-5% addition of the sediments into the depleted mantle source, compared with 1-10% sediments constrained by radiogenic isotopes (Carpentier et al., 2008). References Carpentier, M., Chauvel, C., & Mattielli, N., 2008. Pb-Nd isotopic constraints on sedimentary input into the Lesser Antilles arc system. Earth and Planetary Science Letters, 272(1), 199-211. Carpentier, M., Chauvel, C., Maury, R. C., & Mattielli, N., 2009. The 'zircon effect' as recorded by the chemical and Hf isotopic compositions of Lesser Antilles forearc sediments. Earth and Planetary Science Letters, 287(1), 86-99. Labanieh, S., Chauvel, C., Germa, A., & Quidelleur, X., 2012. Martinique: a Clear Case for Sediment Melting and Slab Dehydration as a Function of Distance to the Trench. Journal of Petrology, 53(12), 2441-2464. Tomascak, P. B., Langmuir, C. H., le Roux, P. J., & Shirey, S. B. (2008). Lithium isotopes in global mid-ocean ridge basalts. Geochimica et Cosmochimica Acta, 72(6), 1626-1637.

In-situ tube burst testing and high-temperature deformation behavior of candidate materials for accident tolerant fuel cladding

DOE PAGES

Byun, Thak Sang; Yamamoto, Yukinori; Maloy, Stuart A.; ...

2015-08-25

Here, one of the most essential properties of accident tolerant fuel (ATF) for maintaining structural integrity during a loss-of-coolant accident (LOCA) is high resistance of the cladding to plastic deformation and burst failure, since the deformation and burst behavior governs the cooling efficiency of flow channels and the process of fission product release. To simulate and evaluate the deformation and burst process of thin-walled cladding, an in-situ testing and evaluation method has been developed on the basis of visual imaging and image analysis techniques. The method uses a specialized optics system consisting of a high-resolution video camera, a light filteringmore » unit, and monochromatic light sources. The in-situ testing is performed using a 50 mm long pressurized thin-walled tubular specimen set in a programmable furnace. As the first application, ten (10) candidate cladding materials for ATF, i.e., five FeCrAl alloys and five nanostructured steels, were tested using the newly developed method, and the time-dependent images were analyzed to produce detailed deformation and burst data such as true hoop stress, strain (creep) rate, and failure stress. Relatively soft FeCrAl alloys deformed and burst below 800 °C, while negligible strain rates were measured for higher strength alloys.« less

Light Emitting Diode Flashlights as Effective and Inexpensive Light Sources for Fluorescence Microscopy

PubMed Central

Robertson, J. Brian; Zhang, Yunfei; Johnson, Carl Hirschie

2009-01-01

Summary Light-emitting diodes (LEDs) are becoming more commonly used as light sources for fluorescence microscopy. We describe the adaptation of a commercially available LED flashlight for use as a source for fluorescence excitation. This light source is long-lived, inexpensive, and is effective for excitation in the range of 440–600 nm. PMID:19772530

Nanophotonic enhanced quantum emitters

NASA Astrophysics Data System (ADS)

Li, Xin; Zhou, Zhang-Kai; Yu, Ying; Gather, Malte; Di Falco, Andrea

2017-08-01

Quantum dots are excellent solid-state quantum sources, because of their stability, their narrow spectral linewidth, and radiative lifetime in the range of 1ns. Most importantly, they can be integrated into more complex nanophononics devices, to realize high quality quantum emitters of single photons or entangled photon sources. Recent progress in nanotechnology materials and devices has opened a number of opportunities to increase, optimize and ultimately control the emission property of single quantum dot. In this work, we present an approach that combines the properties of quantum dots with the flexibility of light control offered by nanoplasmonics and metamaterials structuring. Specifically, we show the nanophotonic enhancement of two types of quantum dots devices. The quantum dots are inserted into optical-positioned micropillar cavities, or decorated on the facets of core-shell GaAs/AlGaAs nanowires, fabricated with a bottom-up approach. In both cases, the metallic nanofeatures, which are designed to control the emission and the polarization state of the emitted light, are realized via direct electron-beam-induced deposition. This approach permits to create three-dimensional features with nanometric resolution and positional accuracy, and does not require wet lithographic steps and previous knowledge of the exact spatial arrangement of the quantum devices.

On the structure of the outer layers of cool carbon stars

NASA Technical Reports Server (NTRS)

Querci, F.; Querci, M.; Wing, R. F.; Cassatella, A.; Heck, A.

1982-01-01

Exposures on the spectra of four late C-type stars have been made with the IUE satellite in the wavelength range of the LWR camera (1900-3200 A). Two Mira variables near maximum light and two semiregular variables were observed. Although the exposure times used, which range up to 240 min in the low-resolution mode, were more than sufficient to record the continuum and emission lines of Mg II, Fe II, and Al II in normal M stars of similar magnitude and temperature, no light was recorded. It is concluded that the far-ultraviolet continuum is strongly depressed in these cool carbon stars. The absence of UV emission lines implies either that the chromospheric lines observed in M stars require an ultraviolet flux for their excitation, or that cool carbon stars have no chromosphere at all or that the opacity source is located above even the emission-line-forming region. This opacity source, which is probably some carbon condensate since it is weak or absent in M stars while absorbing strongly in C stars, is discussed both in terms of the chromospheric interpretation of the emission lines and in terms of their shock-wave interpretation.

Color stable phosphors for LED lamps and methods for preparing them

DOEpatents

Murphy, James Edward; Setlur, Anant Achyut; Camardello, Samuel Joseph

2013-11-26

An LED lamp includes a light source configured to emit radiation with a peak intensity at a wavelength between about 250 nm and about 550 nm; and a phosphor composition configured to be radiationally coupled to the light source. The phosphor composition includes particles of a phosphor of formula I, said particles having a coating composition disposed on surfaces thereof; ((Sr.sub.1-zM.sub.z).sub.1-(x+w)A.sub.wCe.sub.x).sub.3(Al.sub.1-ySi.sub.y-)O.sub.4+y+3(x-w)F.sub.1-y-3(x-w) I wherein the coating composition comprises a material selected from aluminum oxide, magnesium oxide, calcium oxide, barium oxide, strontium oxide, zinc oxide, aluminum hydroxide, magnesium hydroxide, calcium hydroxide, barium hydroxide, strontium hydroxide, zinc hydroxide, aluminum phosphate, magnesium phosphate, calcium phosphate, barium phosphate, strontium phosphate, and combinations thereof; and A is Li, NA, K, or Rb, or a combination thereof; M is Ca, Ba, Mg, Zn, or a combination thereof; and 0

Immunoglobulin Light Chains Form an Extensive and Highly Ordered Fibril Involving the N- and C-Termini.

PubMed

Piehl, Dennis W; Blancas-Mejía, Luis M; Wall, Jonathan S; Kennel, Stephen J; Ramirez-Alvarado, Marina; Rienstra, Chad M

2017-02-28

Light-chain (AL)-associated amyloidosis is a systemic disorder involving the formation and deposition of immunoglobulin AL fibrils in various bodily organs. One severe instance of AL disease is exhibited by the patient-derived variable domain (V L ) of the light chain AL-09, a 108 amino acid residue protein containing seven mutations relative to the corresponding germline protein, κI O18/O8 V L . Previous work has demonstrated that the thermodynamic stability of native AL-09 V L is greatly lowered by two of these mutations, Y87H and N34I, whereas a third mutation, K42Q, further increases the kinetics of fibril formation. However, detailed knowledge regarding the residues that are responsible for stabilizing the misfolded fibril structure is lacking. In this study, using solid-state NMR spectroscopy, we show that the majority of the AL-09 V L sequence is immobilized in the fibrils and that the N- and C-terminal portions of the sequence are particularly well-structured. Thus, AL-09 V L forms an extensively ordered and β-strand-rich fibril structure. Furthermore, we demonstrate that the predominant β-sheet secondary structure and rigidity observed for in vitro prepared AL-09 V L fibrils are qualitatively similar to those observed for AL fibrils extracted from postmortem human spleen tissue, suggesting that this conformation may be representative of a common feature of AL fibrils.

Investigating the effects of abyssal peridotite alteration on Si, Mg and Zn isotopes

NASA Astrophysics Data System (ADS)

Savage, P. S.; Wimpenny, J.; Harvey, J.; Yin, Q.; Moynier, F.

2013-12-01

Around 1/3 of Earth's divergent ridge system is now classified as "slow" spreading [1], exposing ultramafic rocks (abyssal peridotites) at the seafloor. Such material is often highly altered by serpentinisation and steatisation (talc formation). It is crucial to understand such processes in order to access the original composition of the mantle, and to quantify any impact on ocean composition. Here we examine the effect of both serpentinisation and steatisation on Si, Mg and Zn isotopes. Hydrothermal alteration and seafloor weathering are both sources of oceanic Si [2] and weathering of abyssal peridotites is a source of oceanic Mg [3]; hence isotopic fractionation as a result of seafloor alteration could affect oceanic Si and Mg isotope composition. Zinc isotopes can provide complimentary information; the magnitude and direction of fractionation is highly dependent on complexing ligand [4] and can provide compositional information on the fluids driving metasomatism. For this study, two cores from the well-characterised abyssal peridotites recovered on ODP Leg 209 were examined [5]. Hole 1274a peridotites exhibit variable serpentinisation at ~200°C, whereas samples from Hole 1268a have been comprehensively serpentinised and then subsequently steatised to talc facies at ~350°C, by a low Mg/Si, low pH fluid. The Si, Mg and Zn isotope compositions of 1274a samples are extremely homogeneous, identical to that of pristine mantle rocks (BSE) i.e., serpentinisation at this locality was predominantly isochemical [5]. In contrast, samples from 1268a show greater isotopic variability. In all samples, Mg is enriched in the heavier isotopes relative to BSE, consistent with formation of isotopically heavy secondary phases [6]. For Si, serpentinised samples are slightly enriched in the lighter isotopes compared to BSE, again consistent with the behaviour of Si during formation of secondary phases [7]. Within the steatised samples, some exhibit enrichments in the lighter Si isotopes (similar to the serpentinites), however, some are isotopically heavy, relative to BSE. Such samples were found to have abundant chlorite, whose formation requires fluid with high Al activity, likely sourced from late-emplaced gabbroic dykes. The Zn of all 1268a samples are enriched in the lighter isotopes, implying the involvement of isotopically light sulfide precipitation during metasomatism [4]. The consistently heavy Mg isotope data suggest that seafloor alteration of peridotites can input an isotopically light Mg-bearing fluid to the ocean. Fluid composition is less easy to determine from the more complex behaviour observed in Si isotopes, although it is unlikely to substantially deviate from BSE, consistent with previous observations [8]. Finally, the strong enrichment in the lighter isotopes of Zn confirms that this isotope system could be used as a tracer of recycled serpentinised material at arc settings, as suggested in [4]. [1] Dick et al. (2003) Nature 426, 405-412; [2] Treguer and De La Rocha (2013) Ann. Rev. Mar. Sci. 5, 477-501; [3] Snow & Dick (1995) GCA, 59, 4219-4235; [4] Pons et al. (2011) PNAS 108(43) 17639-17643; [5] Bach et al., (2004) G3 5; [6] Tipper et al. (2006) EPSL 247, 267-279; [7] Opfergelt et al. (2012) Chem. Geol. 326, 113-122; [8] De La Rocha et al. (2000) GCA 64, 2467-2477.

Light intensity and quality from sole-source light-emitting diodes impact growth, morphology, and nutrient content of Brassica microgreens

USDA-ARS?s Scientific Manuscript database

Multi-layer vertical production systems using sole-source (SS) lighting can be used for microgreen production; however, traditional SS lighting can consume large amounts of electrical energy. Light-emitting diodes (LEDs) offer many advantages over conventional light sources including: high photoelec...

Possible cometary bioorganic compounds as sources of planetary biospheres

NASA Astrophysics Data System (ADS)

Kobayashi, K.; Takano, Y.; Kaneko, T.; Hashimoto, H.; Saito, T.

Complex organi c compound s were discovered in the coma of Comet Halley [1], whi c h suggested that they w er e p ossibl e sources of the terr estria l biosp here. It has not been confirmed, however, that bioorganic compounds like amino acids were contained in comet ary nuclei. It has been hypothe sized that cometary organic compounds wer e formed in interstellar dust particles (ISDs) [2]. A great nu mber of experiments have been done s imulat i ng the condition o ISDf environments. Amino acids were reported to form in simulated ISD environments by proton irradiation [3] and by UV irradiation [4] of simulat ed ISD ice mantles. Here w e discuss nature of bioorganic compounds formed in simul a t e d ISD environments, and compare wit h those f ormed in simulated primitive planet ary atmospheres. A gas mixt ure of carbon monoxi d e, ammonia and water was irradiated wit h high - energy protons, gamma rays or UV light. All of hydrolysates o f the products gave a wide variety of a ino acids, t ogethe r with uracil a d cytosine. When amn mixture of methanol, ammonia and w at e r (1:1:2.8) was irradiated wit h gamma rays or UV light at 77K, 293K or 353K, am ino acids were also detect e d in each hydrolysates: The G-value ( energy yield) of glycine (the most abundant amino acids in the products) was ca. 0.01, which was independent from the temp eratur e or the phase (s olid, liquid or gas). These results s ugg est that amino acid precursors can be formed in ISD environments quite effe c t i vely even if the materials were frozen in low temperature. If comets can bring sufficient kinds and amount of bioorganic co mpou nds to planets, planetary biospheres can be generated, regardless of the comp osit ion of planet ary atmospheres. It will be quite interesting to find and analyze cometary organics left in planets and satellites such as the moon, as wel l as in cometary bodies. [1] J. Kissel and F. R. Kreuger, Natur e, 326, 755 (1987). [2] J. M. Greenberg and A. Li, Adv. Space Res., 19, 981 (1997). [3] K. Kobayashi, et al., Adv. Space Res ., 16, 21 (1995); T. Kasam atsu, et al., Bull. Chem . Soc. Jpn., 70, 1021 (1997). [4] R. Briggs , et al., Origins Life Evol. Biosphere, 22, 287 (1992); K. Kobayas hi, et al., Adv. Space Res., 23, 401 (1999 ) ; M. P. Bern stein, et al., Nature, 416, 401 (2002); G. M. M unoz Caro, et al., Nature, 416, 403 (2002).

Light Pollution | CTIO

Science.gov Websites

important product so far is Cinzano et al.'s 'First World Atlas of the Artificial Night-Sky Brightness reduction of a factor of two in artificial night-sky brightness will extend the current lifetime of any again reached. A pragmatic, more pessimistic estimate of 7%/annum growth in artificial light pollution

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

Baden, Elizabeth M.; Owen, Barbara A.L.; Peterson, Francis C.

Amyloidoses are devastating and currently incurable diseases in which the process of amyloid formation causes fatal cellular and organ damage. The molecular mechanisms underlying amyloidoses are not well known. In this study, we address the structural basis of immunoglobulin light chain amyloidosis, which results from deposition of light chains produced by clonal plasma cells. We compare light chain amyloidosis protein AL-09 to its wild-type counterpart, the kl O18/O8 light chain germline. Crystallographic studies indicate that both proteins form dimers. However, AL-09 has an altered dimer interface that is rotated 90 degrees from the kl O18/O8 dimer interface. The three non-conservativemore » mutations in AL-09 are located within the dimer interface, consistent with their role in the decreased stability of this amyloidogenic protein. Moreover, AL-09 forms amyloid fibrils more quickly than kl O18/O8 in vitro. These results support the notion that the increased stability of the monomer and delayed fibril formation, together with a properly formed dimer, may be protective against amyloidogenesis. This could open a new direction into rational drug design for amyloidogenic proteins.« less

LED lamp

DOEpatents

Galvez, Miguel; Grossman, Kenneth; Betts, David

2013-11-12

There is herein described a lamp for providing white light comprising a plurality of light sources positioned on a substrate. Each of said light sources comprises a blue light emitting diode (LED) and a dome that substantially covers said LED. A first portion of said blue light from said LEDs is transmitted through said domes and a second portion of said blue light is converted into a red light by a first phosphor contained in said domes. A cover is disposed over all of said light sources that transmits at least a portion of said red and blue light emitted by said light sources. The cover contains a second phosphor that emits a yellow light in response to said blue light. The red, blue and yellow light combining to form the white light and the white light having a color rendering index (CRI) of at least about 80.

Faraday Rotation as a Probe of Coronal Mass Ejections

NASA Astrophysics Data System (ADS)

Kooi, J. E.; Spangler, S. R.; Kassim, N. E.

2016-12-01

Coronal mass ejections (CMEs) are large-scale eruptions of plasma from the Sun that play an important role in space weather. Although CMEs have been an active field of research since their discovery in the 1970s, there is still much to understand about the plasma structure of CMEs. Faraday rotation (FR) is the rotation of the plane of polarization that results when a linearly polarized signal passes through a magnetized plasma such as a CME. FR observations of a source near the Sun can provide information on the plasma structure of a CME shortly after launch. We made sensitive Very Large Array (VLA) full-polarization observations in August, 2012, using 1 — 2 GHz frequencies of a "constellation" of radio sources through the solar corona at heliocentric distances that ranged from 6 — 15 solar radii. Of the nine sources observed, three were occulted by CMEs. In addition to our radioastronomical observations, which represent one of the first active hunts for CME Faraday rotation since Bird et al. (1985) and the first active hunt using the VLA, we obtained white-light coronagraph images from the LASCO/C3 instrument to determine the Thomson scattering brightness, BT, providing a means to independently estimate the plasma density and determine its contribution to the observed Faraday rotation. A constant density force-free flux rope embedded in the background corona was used to model the effects of the CMEs on BT and FR. The single flux rope model successfully reproduces the observed BT and FR profiles for two sources. The third source (0843+1547) was occulted by two CMEs and, therefore, we modeled observations of this source using two flux ropes embedded in the background corona. The two flux rope model successfully reproduces both BT and FR profiles for 0843+1547 and, in particular, the two flux rope model successfully replicates the appropriate slope in FR before and after occultation by the second CME and predicts the observed change in sign to FR > 0 at the end of the observing session. The plasma densities (6 — 22 × 103 cm-3) and axial magnetic field strengths (2 — 12 mG) inferred from our models are consistent with the modeling work of Liu et al. (2007) and Jensen et al. (2008), as well as previous CME FR observations by Bird et al. (1985). This work was supported at the University of Iowa by grant ATM09-56901.

MICROSCANNING XRF, XANES, AND XRD STUDIES OF THEDECORATED SURFACE OF ROMAN TERRA SIGILLATA CERAMICS

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

Mirguet, C.; Sciau, P.; Goudeau, P.

Different microscanning synchrotron techniques were used to better understand the elaboration process and origins of Terra Sigillata potteries from the Roman period. A mixture Gallic slip sample cross-section showing red and yellow colors was studied. The small (micron) size of the X-ray beam available at Stanford Synchrotron Radiation Laboratory (SSRL) and Advanced Light Source (ALS) synchrotron sources, coupled with the use of a sample scanning stage allowed us to spatially resolve the distribution of the constitutive mineral phases related to the chemical composition. Results show that red color is a result of iron-rich hematite crystals and the yellow part ismore » a result of the presence of Ti-rich rutile-type phase (brookite). Volcanic-type clay is at the origin of these marble Terra Sigillata.« less

Optical readout of a two phase liquid argon TPC using CCD camera and THGEMs

NASA Astrophysics Data System (ADS)

Mavrokoridis, K.; Ball, F.; Carroll, J.; Lazos, M.; McCormick, K. J.; Smith, N. A.; Touramanis, C.; Walker, J.

2014-02-01

This paper presents a preliminary study into the use of CCDs to image secondary scintillation light generated by THick Gas Electron Multipliers (THGEMs) in a two phase LAr TPC. A Sony ICX285AL CCD chip was mounted above a double THGEM in the gas phase of a 40 litre two-phase LAr TPC with the majority of the camera electronics positioned externally via a feedthrough. An Am-241 source was mounted on a rotatable motion feedthrough allowing the positioning of the alpha source either inside or outside of the field cage. Developed for and incorporated into the TPC design was a novel high voltage feedthrough featuring LAr insulation. Furthermore, a range of webcams were tested for operation in cryogenics as an internal detector monitoring tool. Of the range of webcams tested the Microsoft HD-3000 (model no:1456) webcam was found to be superior in terms of noise and lowest operating temperature. In ambient temperature and atmospheric pressure 1 ppm pure argon gas, the THGEM gain was ≈ 1000 and using a 1 msec exposure the CCD captured single alpha tracks. Successful operation of the CCD camera in two-phase cryogenic mode was also achieved. Using a 10 sec exposure a photograph of secondary scintillation light induced by the Am-241 source in LAr has been captured for the first time.

Io's SO2 Atmosphere Viewed in Silhouette by Jupiter Lyman-α

NASA Astrophysics Data System (ADS)

Retherford, Kurt D.; Roth, Lorenz; Feaga, Lori M.; Becker, Tracy M.; Tsang, Constantine; Jessup, Kandis-Lea; Grava, Cesare

2016-10-01

We report a new technique for mapping Io's SO2 vapor distribution. Hubble's Space Telescope Imaging Spectrograph (STIS) instrument observed Io during four Jupiter transit events to obtain medium resolution far-UV spectral images near the Lyman-α wavelength of 121.6 nm. Jupiter's bright Lyman-α dayglow provides a background light source for opacity measurements, much like during a stellar occultation or transiting exoplanet event. Peaks in the photoabsorption cross-sections for sulfur dioxide occur near 122 nm, with resulting absorptions raising the altitude where a tangential line of sight opacity of tau=1 is detected up to resolvable distances above the disk. This method of measuring column densities along lines of sight above the limb complements Lyman-α reflectance imaging and other methods for measuring Io's SO2 gas. For example, interpretation of Io's surface reflected components at far-UV wavelengths is complicated by SO2 frost features being correlated with regions of known volcanic outgassing activity, while Jupiter's Lyman-α dayglow provides a more spatially uniform background light source. Initial examination of these near-terminator limb observations with STIS confirms the findings from previous Lyman-α disk reflectance imaging using STIS's G140L mode (e.g., Feldman et al., GRL, 2000; Feaga et al. 2009) that Io's polar SO2 density is roughly an order of magnitude lower than found at the equator. As Strobel & Wolven (2001) described it, Io appears to wear its dayside atmosphere as "a belt" around the equator. We describe detailed simulations, now underway, that incorporate the STIS point spread function and consideration of additional attenuation by atmospheric hydrogen atoms, which are produced by charge exchange reactions between magnetospheric protons and Io's atmosphere.

Evaluating Bay Area Methane Emission Inventory

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

Fischer, Marc; Jeong, Seongeun

As a regulatory agency, evaluating and improving estimates of methane (CH4) emissions from the San Francisco Bay Area is an area of interest to the Bay Area Air Quality Management District (BAAQMD). Currently, regional, state, and federal agencies generally estimate methane emissions using bottom-up inventory methods that rely on a combination of activity data, emission factors, biogeochemical models and other information. Recent atmospheric top-down measurement estimates of methane emissions for the US as a whole (e.g., Miller et al., 2013) and in California (e.g., Jeong et al., 2013; Peischl et al., 2013) have shown inventories underestimate total methane emissions bymore » ~ 50% in many areas of California, including the SF Bay Area (Fairley and Fischer, 2015). The goal of this research is to provide information to help improve methane emission estimates for the San Francisco Bay Area. The research effort builds upon our previous work that produced methane emission maps for each of the major source sectors as part of the California Greenhouse Gas Emissions Measurement (CALGEM) project (http://calgem.lbl.gov/prior_emission.html; Jeong et al., 2012; Jeong et al., 2013; Jeong et al., 2014). Working with BAAQMD, we evaluate the existing inventory in light of recently published literature and revise the CALGEM CH4 emission maps to provide better specificity for BAAQMD. We also suggest further research that will improve emission estimates. To accomplish the goals, we reviewed the current BAAQMD inventory, and compared its method with those from the state inventory from the California Air Resources Board (CARB), the CALGEM inventory, and recent published literature. We also updated activity data (e.g., livestock statistics) to reflect recent changes and to better represent spatial information. Then, we produced spatially explicit CH4 emission estimates on the 1-km modeling grid used by BAAQMD. We present the detailed activity data, methods and derived emission maps by sector. In total, we estimate the anthropogenic emissions for BAAQMD to be 116.4 Gg (1 Gg = 109 g) CH4/yr, with a likely uncertainty of ~ 50% or more (e.g., NRC, 2010; US-EPA, 2015). Including the emissions from wetland (Jeong et al., 2013), the total CH4 emission estimate for BAAQMD is 120.1 Gg CH4/yr. Table 1 summarizes the estimated CH4 emissions for 2011 by sector. The sectors were categorized following those that are used in recent regional emission quantification studies (e.g., Jeong et al., 2013; Peischl et al., 2013; Wecht et al., 2014). However, we note that this result is marginally lower than the top-down estimate of 240 ± 60 Gg CH4/yr (at 95% confidence) reported by Fairley and Fischer (2015), suggesting some combination of systematic error in the top-down estimate, underestimation of emissions from known sources, or as yet unidentified sources may be present. With respect to the relative contributions from different source sectors, the CH4 emissions from the region are dominated by urban activities. Landfill emissions represent 53% of the District’s total emission followed by livestock (16%) and natural gas (15%). These three dominant sectors account for 84% of the total anthropogenic emission in BAAQMD. This suggests that mitigation efforts need to focus on these three sources. Figure 1 shows the gridded anthropogenic CH4 emissions on the BAAQMD’s 1-km grid. In general, the spatial pattern of emissions follows the density of population while strong point sources are also distributed in the rural areas of the District. Detailed methods and emissions for each sector and county are described in the following sections.« less

Photonic crystal light source

DOEpatents

Fleming, James G [Albuquerque, NM; Lin, Shawn-Yu [Albuquerque, NM; Bur, James A [Corrales, NM

2004-07-27

A light source is provided by a photonic crystal having an enhanced photonic density-of-states over a band of frequencies and wherein at least one of the dielectric materials of the photonic crystal has a complex dielectric constant, thereby producing enhanced light emission at the band of frequencies when the photonic crystal is heated. The dielectric material can be a metal, such as tungsten. The spectral properties of the light source can be easily tuned by modification of the photonic crystal structure and materials. The photonic crystal light source can be heated electrically or other heating means. The light source can further include additional photonic crystals that exhibit enhanced light emission at a different band of frequencies to provide for color mixing. The photonic crystal light source may have applications in optical telecommunications, information displays, energy conversion, sensors, and other optical applications.

A compact, coherent light source system architecture

NASA Astrophysics Data System (ADS)

Biedron, S. G.; Dattoli, G.; DiPalma, E.; Einstein, J.; Milton, S. V.; Petrillo, V.; Rau, J. V.; Sabia, E.; Spassovsky, I. P.; van der Slot, P. J. M.

2016-09-01

Our team has been examining several architectures for short-wavelength, coherent light sources. We are presently exploring the use and role of advanced, high-peak power lasers for both accelerating the electrons and generating a compact light source with the same laser. Our overall goal is to devise light sources that are more accessible by industry and in smaller laboratory settings. Although we cannot and do not want to compete directly with sources such as third-generation light sources or that of national-laboratory-based free-electron lasers, we have several interesting schemes that could bring useful and more coherent, short-wavelength light source to more researchers. Here, we present and discuss several results of recent simulations and our future steps for such dissemination.

Intense X-ray and EUV light source

DOEpatents

Coleman, Joshua; Ekdahl, Carl; Oertel, John

2017-06-20

An intense X-ray or EUV light source may be driven by the Smith-Purcell effect. The intense light source may utilize intense electron beams and Bragg crystals. This may allow the intense light source to range from the extreme UV range up to the hard X-ray range.

Carambola optics for recycling of light.

PubMed

Leutz, Ralf; Fu, Ling; Ries, Harald

2006-04-20

Recycling of light allows the luminance (radiance) emitted by a light source to be increased at the cost of reducing the total luminous flux (radiant power). Recycling of light means returning part of the emitted light to the source, where part of it will escape absorption. An optical design that is suitable for multiple and controlled recycling is described. Carambola optics is named for its resemblance to star fruit. Several pairs of mirrors or prisms redirect light repeatedly onto the source, thus achieving multiple transits of the light through the source. This recycled light exits the carambola in the same phase space as light directly emitted and not recycled.

Suppression of electron overflow in 370-nm InGaN/AlGaN ultraviolet light emitting diodes with different insertion layer thicknesses

NASA Astrophysics Data System (ADS)

Wang, C. K.; Wang, Y. W.; Chiou, Y. Z.; Chang, S. H.; Jheng, J. S.; Chang, S. P.; Chang, S. J.

2017-06-01

In this study, the properties of 370-nm InGaN/AlGaN ultraviolet light emitting diodes (UV LEDs) with different thicknesses of un-doped Al0.3Ga0.7N insertion layer (IL) between the last quantum barrier and electron blocking layer (EBL) have been numerically simulated by Advance Physical Model of Semiconductor Devices (APSYS). The results show that the LEDs using the high Al composition IL can effectively improve the efficiency droop, light output power, and internal quantum efficiency (IQE) compared to the original structure. The improvements of the optical properties are mainly attributed to the energy band discontinuity and offset created by IL, which increase the potential barrier height of conduction band to suppress the electron overflow from the active region to the p-side layer.

AFM AND XPS Characterization of Zinc-Aluminum Alloy Coatings with Attention to Surface Dross and Flow Lines

NASA Astrophysics Data System (ADS)

Harding, Felipe A.; Alarcon, Nelson A.; Toledo, Pedro G.

Surfaces of various zinc-aluminum alloy (Zn-Al) coated steel samples are studied with attention to foreign surface dross by atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS/ESCA). AFM topographic maps of zinc-aluminum alloy surfaces free of dross reveal the perfect nanoscale details of two kinds of dendrites: branched and globular. In all magnifications the dendrites appear smooth and, in general, very clean. XPS analysis of the extreme surface of a Zn-Al sample reveals Al, Zn, Si and O as the main components. The XPS results show no segregation or separation of phases other than those indicated by the ternary Al-Zn-Si diagram. For surfaces of Zn-Al plagued with impurities, high resolution AFM topographic maps reveal three situations: (1) areas with well-defined dendrites, relatively free of dross; (2) areas with small, millimeter-sized black spots known as dross; and (3) areas with large black stains, known as flow lines. Dendrite deformation and dross accumulation increase notably in the neighborhood, apparently clean to the naked eye, of dross or flow lines. XPS results of areas with dross and flow lines indicate unacceptable high concentration of Si and important Si phase separation. These results, in the light of AFM work, reveal that dross and flow lines are a consequence of a high local concentration of Si from high melting point silica and silicate impurities in the Zn-Al alloy source.

First resonant tunneling via a light-hole ground state

NASA Astrophysics Data System (ADS)

Lampin, J. F.; Mollot, F.

1998-07-01

We report the demonstration of resonant tunneling of light-holes through an AlAs/GaAs 0.7P 0.3 double-barrier heterostructure. The tensile strain in the quantum well reverses the order of the light- and heavy-hole levels, the first light-hole level becoming the ground state. The I( V) characteristics are measured at different temperatures and compared to those of a standard AlAs/GaAs unstrained structure. The peak current density of the first light-hole resonance and its peak-to-valley current ratio are enhanced. They reach 28 A/cm 2 and 3.4 : 1 at 15 K. A negative differential resistance is observed up to 250 K.

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.

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

2015-08-25

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.

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.

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.

Assessment of the actual light dose in photodynamic therapy.

PubMed

Schaberle, Fabio A

2018-06-09

Photodynamic therapy (PDT) initiates with the absorption of light, which depends on the spectral overlap between the light source emission and the photosensitizer absorption, resulting in the number of photons absorbed, the key parameter starting PDT processes. Most papers report light doses regardless if the light is only partially absorbed or shifted relatively to the absorption peak, misleading the actual light dose value and not allowing quantitative comparisons between photosensitizers and light sources. In this manuscript a method is presented to calculate the actual light dose delivered by any light source for a given photosensitizer. This method allows comparing light doses delivered for any combination of light source (broad or narrow band or daylight) and photosensitizer. Copyright © 2018. Published by Elsevier B.V.

Phototoxic effect of aluminium-chlorine and aluminium-hydroxide phthalocyanines on Leishmania (l.) amazonensis.

PubMed

Nesi-Reis, V; Navasconi, T R; Lera-Nosone, D S S L; Oliveira, E L; Barbosa, P M; Caetano, W; Silveira, T G V; Aristides, S M A; Hioka, N; Lonardoni, M V C

2018-03-01

This study investigated the activity of photosensitive phthalocyanines on promastigotes and amastigotes of Leishmania (L.) amazonensis. Aluminum phthalocyanine chloride (AlPcCl), Aluminum phthalocyanine hydroxide (AlPcOH) and zinc phthalocyanine (PcZn) were tested in the presence (matte red LED, potency of 2.5-2.3 μW for 30 min) and absence of light against L. amazonensis promastigotes and the parasite viability was evaluated after 24, 48 and 72 h. The amastigote forms were treated with AlPcCl and AlPcOH, following the same lighting protocols described for the promastigote forms, being evaluated after 24 h. Cytotoxicity to human erythrocytes and peritoneal macrophages was also evaluated. The results showed that AlPcCl and AlPcOH in the presence of light have antileishmania activity, with leishmanistatic effects on promastigotes and amastigotes of L. amazonensis, without causing cytotoxicity to peritoneal macrophages and erythrocytes. The concentrations that inhibited 50% of the promastigote forms after 24 h of light exposure were 0.21 ± 0.08 μM for AlPcCl and 0.23 ± 0.06 μM for AlPcOH. In 48 h and 72 h after the treatment, the IC 50 of AlPcCl was 0.13 ± 0.02 and 0.12 ± 0.03 μM and for AlPcOH was 0.14 ± 0.01 μM and 0.11 ± 0.01 μM, respectively. PcZn showed no activity on promastigotes of L. amazonensis. This study showed a substantial photodynamic activity of the phthalocyanines AlPcCl and AlPcOH against intracellular amastigotes forms of L. amazonensis after irradiation, presenting IC 50 values of 0.62 ± 0.06 μM and 0.92 ± 0.12 μM, respectively. These results support the possibility of using photodynamic therapy for the treatment of cutaneous leishmaniasis. Copyright © 2017 Elsevier B.V. All rights reserved.

Total x-ray power measurements in the Sandia LIGA program.

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

Malinowski, Michael E.; Ting, Aili

2005-08-01

Total X-ray power measurements using aluminum block calorimetry and other techniques were made at LIGA X-ray scanner synchrotron beamlines located at both the Advanced Light Source (ALS) and the Advanced Photon Source (APS). This block calorimetry work was initially performed on the LIGA beamline 3.3.1 of the ALS to provide experimental checks of predictions of the LEX-D (LIGA Exposure- Development) code for LIGA X-ray exposures, version 7.56, the version of the code in use at the time calorimetry was done. These experiments showed that it was necessary to use bend magnet field strengths and electron storage ring energies different frommore » the default values originally in the code in order to obtain good agreement between experiment and theory. The results indicated that agreement between LEX-D predictions and experiment could be as good as 5% only if (1) more accurate values of the ring energies, (2) local values of the magnet field at the beamline source point, and (3) the NIST database for X-ray/materials interactions were used as code inputs. These local magnetic field value and accurate ring energies, together with NIST database, are now defaults in the newest release of LEX-D, version 7.61. Three dimensional simulations of the temperature distributions in the aluminum calorimeter block for a typical ALS power measurement were made with the ABAQUS code and found to be in good agreement with the experimental temperature data. As an application of the block calorimetry technique, the X-ray power exiting the mirror in place at a LIGA scanner located at the APS beamline 10 BM was measured with a calorimeter similar to the one used at the ALS. The overall results at the APS demonstrated the utility of calorimetry in helping to characterize the total X-ray power in LIGA beamlines. In addition to the block calorimetry work at the ALS and APS, a preliminary comparison of the use of heat flux sensors, photodiodes and modified beam calorimeters as total X-ray power monitors was made at the ALS, beamline 3.3.1. This work showed that a modification of a commercially available, heat flux sensor could result in a simple, direct reading beam power meter that could be a useful for monitoring total X-ray power in Sandia's LIGA exposure stations at the ALS, APS and Stanford Synchrotron Radiation Laboratory (SSRL).« less

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

Tracy, Jenny; Jacobson, Arne; Mills, Evan

Flashlights that use LED technology have quickly emerged as the dominant source of portable lighting in Kenya. While flashlights do not normally provide a substitute for kerosene and other highly inefficient fuels, they are an important early manifestation of LED lighting in the developing world that can serve as a platform - or deterrent - to the diffusion of the technology into the broader off-grid lighting market. The lead acid batteries embedded in flashlights also represent an important source of hazardous waste, and flashlight durability is thus an important determinant of the rate of waste disposal. Low-cost LED flashlights withmore » prices from $1 to $4 are now widely available in shops and markets throughout Kenya. The increased penetration of LED technology in the flashlight market is significant, as over half of all Kenyan households report owning a flashlight (Kamfor, 2002). While this shift from conventional incandescent technology to modern LEDs may appear to be a promising development, end users that our research team interviewed expressed a number of complaints about the quality and performance of these new flashlights. This raises concerns about the interests of low-income flashlight users, and it may also indicate the onset of a broader market spoiling effect for off-grid lighting products based on LED technology (Mills and Jacobson, 2008; Lighting Africa, 2007). The quality of low-cost LED flashlights can contribute to market spoiling because these products appear to represent the first contact that most Kenyans have with LED technology. In this report, our team uses interviews with 46 end users of flashlights to collect information about their experiences, perceptions, and preferences. We focus especially on highlighting common complaints from respondents about the flashlights that they have used, as well as on noting the features that they indicated were important when evaluating the quality of a flashlight. In previous laboratory tests, researchers from our team found a wide range of quality and performance among battery powered LED lights (Granderson, et al. 2008).« less

Plasmon-enhanced Electrically Light-emitting from ZnO Nanorod Arrays/p-GaN Heterostructure Devices

PubMed Central

Lu, Junfeng; Shi, Zengliang; Wang, Yueyue; Lin, Yi; Zhu, Qiuxiang; Tian, Zhengshan; Dai, Jun; Wang, Shufeng; Xu, Chunxiang

2016-01-01

Effective and bright light-emitting-diodes (LEDs) have attracted broad interests in fundamental research and industrial application, especially on short wavelength LEDs. In this paper, a well aligned ZnO nanorod arrays grown on the p-GaN substrate to form a heterostructured light-emitting diode and Al nanoparticles (NPs) were decorated to improve the electroluminescence performance. More than 30-folds enhancement of the electroluminescence intensity was obtained compared with the device without Al NPs decoration. The investigation on the stable and transient photoluminescence spectraof the ZnO nanorod arrays before and after Al NPs decoration demonstrated that the metal surface plasmon resonance coupling with excitons of ZnO leads to the enhancement of the internal quantum efficiency (IQE). Our results provide aneffective approach to design novel optoelectronic devices such as light-emitting diodes and plasmonic nanolasers. PMID:27181337

Plasmon-enhanced Electrically Light-emitting from ZnO Nanorod Arrays/p-GaN Heterostructure Devices.

PubMed

Lu, Junfeng; Shi, Zengliang; Wang, Yueyue; Lin, Yi; Zhu, Qiuxiang; Tian, Zhengshan; Dai, Jun; Wang, Shufeng; Xu, Chunxiang

2016-05-16

Effective and bright light-emitting-diodes (LEDs) have attracted broad interests in fundamental research and industrial application, especially on short wavelength LEDs. In this paper, a well aligned ZnO nanorod arrays grown on the p-GaN substrate to form a heterostructured light-emitting diode and Al nanoparticles (NPs) were decorated to improve the electroluminescence performance. More than 30-folds enhancement of the electroluminescence intensity was obtained compared with the device without Al NPs decoration. The investigation on the stable and transient photoluminescence spectraof the ZnO nanorod arrays before and after Al NPs decoration demonstrated that the metal surface plasmon resonance coupling with excitons of ZnO leads to the enhancement of the internal quantum efficiency (IQE). Our results provide aneffective approach to design novel optoelectronic devices such as light-emitting diodes and plasmonic nanolasers.

Quantitative phase imaging of biological cells using spatially low and temporally high coherent light source.

PubMed

Ahmad, Azeem; Dubey, Vishesh; Singh, Gyanendra; Singh, Veena; Mehta, Dalip Singh

2016-04-01

In this Letter, we demonstrate quantitative phase imaging of biological samples, such as human red blood cells (RBCs) and onion cells using narrow temporal frequency and wide angular frequency spectrum light source. This type of light source was synthesized by the combined effect of spatial, angular, and temporal diversity of speckle reduction technique. The importance of using low spatial and high temporal coherence light source over the broad band and narrow band light source is that it does not require any dispersion compensation mechanism for biological samples. Further, it avoids the formation of speckle or spurious fringes which arises while using narrow band light source.

Differential recruitment efficacy of patient-derived amyloidogenic and myeloma light chain proteins by synthetic fibrils-A metric for predicting amyloid propensity.

PubMed

Martin, Emily B; Williams, Angela; Wooliver, Craig; Heidel, R Eric; Adams, Sarah; Dunlap, John; Ramirez-Alvarado, Marina; Blancas-Mejia, Luis M; Lands, Ronald H; Kennel, Stephen J; Wall, Jonathan S

2017-01-01

Monoclonal free light chain (LC) proteins are present in the circulation of patients with immunoproliferative disorders such as light chain (AL) amyloidosis and multiple myeloma (MM). Light chain-associated amyloid is a complex pathology composed of proteinaceous fibrils and extracellular matrix proteins found in all patients with AL and in ~10-30% of patients who presented with MM. Amyloid deposits systemically in multiple organs and tissues leading to dysfunction and ultimately death. The overall survival of patients with amyloidosis is worse than for those with early stage MM. We have developed a sensitive binding assay quantifying the recruitment of full length, patient-derived LC proteins by synthetic amyloid fibrils, as a method for studying their amyloidogenic potential. In a survey of eight urinary LC, both AL and MM-associated proteins were recruited by synthetic amyloid fibrils; however, AL-associated LC bound significantly more efficiently (p < 0.05) than did MM LCs. The LC proteins used in this study were isolated from urine and presumed to represent a surrogate of serum free light chains. The binding of LC to synthetic fibrils in this assay accurately differentiated LC with amyloidogenic propensity from MM LC that were not associated with clinical amyloid disease. Notably, the LC from a MM patient who subsequently developed amyloid behaved as an AL-associated protein in the assay, indicating the possibility for identifying MM patients at risk for developing amyloidosis based on the light chain recruitment efficacy. With this information, at risk patients can be monitored more closely for the development of amyloidosis, allowing timely administration of novel, amyloid-directed immunotherapies-this approach may improve the prognosis for these patients.

Comparison of light harmonic generation in Al and Ge consisted silicate materials

NASA Astrophysics Data System (ADS)

Smirnov, Vitaly A.; Vostrikova, Liubov I.

2018-04-01

The silicate materials are perspective for different areas of laser physics and photonics. In this paper the comparison of the nonlinear conversion with the generation of the light harmonic in Al- and Ge-containing silicate materials is presented. The peculiarities of the processes of the light harmonic generation in dependence on the concentrations of the chemical components are discussed and the influences of the additional small inclusion of the elements of fifth group and the rare-earth elements are estimated.

Temporal and Spectral Characteristics of X-Ray Bright Pleiads

NASA Astrophysics Data System (ADS)

Caillault, J.-P.; Gagne, M.; Yglesias, J.; Hartmann, L.; Prosser, C.; Stauffer, J.

1993-05-01

ROSAT PSPC observations of the Pleiades have allowed us to analyze the spectral and temporal characteristics of the X-ray sources within the cluster. Of the ~ 300 sources detected within the images, ~ 20-30 of them seem to be variable at the 99% confidence level (chi (2) -test). Numerous flares have also been found, the light curves of which we display. In addition, we have fit two-temperature Raymond-Smith thermal plasma models to the spectra of the ~ 6 brightest sources and examined whether these sources behave in accordance with coronal loop models. We also demonstrate that the two-temperature fit changes during a flare. We have constructed composite spectra for both shallow and deep convective zone stars in order to see whether there is a systematic change of spectral characteristics from spectral type F to M. Finally, in an attempt to discern possible evolutionary effects, we compare our results with those from the older Hyades cluster (Stern et al. 1993). This research was supported by NASA Grants NAG5-1608 to UGA and NAG5-1849 & NAGW-2698 to the CfA.

'Standing on the Shoulders of Giants': Recontextualization in Writing from Sources.

PubMed

Li, Yongyan

2015-10-01

Despite calls for more research into the writing expertise of senior scientists, the literature reveals surprisingly little about the writing strategies of successful scientist writers. The present paper addresses the gap in the literature by reporting a study that investigated the note-taking strategies of an expert writer, a Chinese professor of biochemistry. Primarily based on interview data, the paper describes the expert's recontextualization (Linell, Text 18:143-157, 1998) strategies at three levels: 'accumulating writing materials' by modifying source texts, composing from 'collections' of cut-and-pasted chunks in drafting a review article, and adopting reusable citations in sources as a 'map'. It is emphasized that through repeatedly revising his paper in light of his rhetorical intentions in a new context of meaning, the expert writer would maximally recontextualize the source-based text segments and citations in the paper, averting transgressive intertextuality (Chandrasoma et al., J Lang Identity Educ 3:171-193, 2004) as a result. The paper ends by highlighting the pedagogical implications of the study for English for Professional Academic Purposes (EPAP).

Multi-band Emission Light Curves of Jupiter: Insights on Brown Dwarfs and Directly Imaged Exoplanets

NASA Astrophysics Data System (ADS)

Zhang, Xi; Ge, Huazhi; Orton, Glenn S.; Fletcher, Leigh N.; Sinclair, James; Fernandes, Joshua; Momary, Thomas W.; Kasaba, Yasumasa; Sato, Takao M.; Fujiyoshi, Takuya

2016-10-01

Many brown dwarfs exhibit significant infrared flux variability (e.g., Artigau et al. 2009, ApJ, 701, 1534; Radigan et al. 2012, ApJ, 750, 105), ranging from several to twenty percent of the brightness. Current hypotheses include temperature variations, cloud holes and patchiness, and cloud height and thickness variations (e.g., Apai et al. 2013, ApJ, 768, 121; Robinson and Marley 2014, ApJ, 785, 158; Zhang and Showman 2014, ApJ, 788, L6). Some brown dwarfs show phase shifts in the light curves among different wavelengths (e.g., Buenzli et al. 2012, ApJ, 760, L31; Yang et al. 2016, arXiv:1605.02708), indicating vertical variations of the cloud distribution. The current observational technique can barely detect the brightness changes on the surfaces of nearby brown dwarfs (Crossfield et al. 2014, Nature, 505, 654) let alone resolve detailed weather patterns that cause the flux variability. The infrared emission maps of Jupiter might shed light on this problem. Using COMICS at Subaru Telescope, VISIR at Very Large Telescope (VLT) and NASA's Infrared Telescope Facility (IRTF), we obtained infrared images of Jupiter over several nights at multiple wavelengths that are sensitive to several pressure levels from the stratosphere to the deep troposphere below the ammonia clouds. The rotational maps and emission light curves are constructed. The individual pixel brightness varies up to a hundred percent level and the variation of the full-disk brightness is around several percent. Both the shape and amplitude of the light curves are significantly distinct at different wavelengths. Variation of light curves at different epochs and phase shift among different wavelengths are observed. We will present principle component analysis to identify dominant emission features such as stable vortices, cloud holes and eddies in the belts and zones and strong emissions in the aurora region. A radiative transfer model is used to simulate those features to get a more quantitative understanding. This work provides rich insights on the relationship between observed light curves and weather on brown dwarfs and perhaps on directly imaged exoplanets in the future.

A novel amblyopia treatment system based on LED light source

NASA Astrophysics Data System (ADS)

Zhang, Xiaoqing; Chen, Qingshan; Wang, Xiaoling

2011-05-01

A novel LED (light emitting diode) light source of five different colors (white, red, green, blue and yellow) is adopted instead of conventional incandescent lamps for an amblyopia treatment system and seven training methods for rectifying amblyopia are incorporated so as for achieving an integrated therapy. The LED light source is designed to provide uniform illumination, adjustable light intensity and alterable colors. Experimental tests indicate that the LED light source operates steadily and fulfills the technical demand of amblyopia treatment.

A novel amblyopia treatment system based on LED light source

NASA Astrophysics Data System (ADS)

Zhang, Xiaoqing; Chen, Qingshan; Wang, Xiaoling

2010-12-01

A novel LED (light emitting diode) light source of five different colors (white, red, green, blue and yellow) is adopted instead of conventional incandescent lamps for an amblyopia treatment system and seven training methods for rectifying amblyopia are incorporated so as for achieving an integrated therapy. The LED light source is designed to provide uniform illumination, adjustable light intensity and alterable colors. Experimental tests indicate that the LED light source operates steadily and fulfills the technical demand of amblyopia treatment.

2A4 binds soluble and insoluble light chain aggregates from AL amyloidosis patients and promotes clearance of amyloid deposits by phagocytosis †.

PubMed

Renz, Mark; Torres, Ronald; Dolan, Philip J; Tam, Stephen J; Tapia, Jose R; Li, Lauri; Salmans, Joshua R; Barbour, Robin M; Shughrue, Paul J; Nijjar, Tarlochan; Schenk, Dale; Kinney, Gene G; Zago, Wagner

2016-09-01

Amyloid light chain (AL) amyloidosis is characterized by misfolded light chain (LC) (amyloid) deposition in various peripheral organs, leading to progressive dysfunction and death. There are no regulatory agency-approved treatments for AL amyloidosis, and none of the available standard of care approaches directly targets the LC protein that constitutes the amyloid. NEOD001, currently in late-stage clinical trials, is a conformation-specific, anti-LC antibody designed to specifically target misfolded LC aggregates and promote phagocytic clearance of AL amyloid deposits. The present study demonstrated that the monoclonal antibody 2A4, the murine form of NEOD001, binds to patient-derived soluble and insoluble LC aggregates and induces phagocytic clearance of AL amyloid in vitro. 2A4 specifically labeled all 21 fresh-frozen organ samples studied, which were derived from 10 patients representing both κ and λ LC amyloidosis subtypes. 2A4 immunoreactivity largely overlapped with thioflavin T-positive labeling, and 2A4 bound both soluble and insoluble LC aggregates extracted from patient tissue. Finally, 2A4 induced macrophage engagement and phagocytic clearance of AL amyloid deposits in vitro. These findings provide further evidence that 2A4/NEOD001 can effectively clear and remove human AL-amyloid from tissue and further support the rationale for the evaluation of NEOD001 in patients with AL amyloidosis.

The Inverse-Square Law with Data Loggers

ERIC Educational Resources Information Center

Bates, Alan

2013-01-01

The inverse-square law for the intensity of light received at a distance from a light source has been verified using various experimental techniques. Typical measurements involve a manual variation of the distance between a light source and a light sensor, usually by sliding the sensor or source along a bench, measuring the source-sensor distance…

Colors of attraction: Modeling insect flight to light behavior.

PubMed

Donners, Maurice; van Grunsven, Roy H A; Groenendijk, Dick; van Langevelde, Frank; Bikker, Jan Willem; Longcore, Travis; Veenendaal, Elmar

2018-06-26

Light sources attract nocturnal flying insects, but some lamps attract more insects than others. The relation between the properties of a light source and the number of attracted insects is, however, poorly understood. We developed a model to quantify the attractiveness of light sources based on the spectral output. This model is fitted using data from field experiments that compare a large number of different light sources. We validated this model using two additional datasets, one for all insects and one excluding the numerous Diptera. Our model facilitates the development and application of light sources that attract fewer insects without the need for extensive field tests and it can be used to correct for spectral composition when formulating hypotheses on the ecological impact of artificial light. In addition, we present a tool allowing the conversion of the spectral output of light sources to their relative insect attraction based on this model. © 2018 Wiley Periodicals, Inc.

Geometrical analysis of an optical fiber bundle displacement sensor

NASA Astrophysics Data System (ADS)

Shimamoto, Atsushi; Tanaka, Kohichi

1996-12-01

The performance of a multifiber optical lever was geometrically analyzed by extending the Cook and Hamm model [Appl. Opt. 34, 5854-5860 (1995)] for a basic seven-fiber optical lever. The generalized relationships between sensitivity and the displacement detection limit to the fiber core radius, illumination irradiance, and coupling angle were obtained by analyses of three various types of light source, i.e., a parallel beam light source, an infinite plane light source, and a point light source. The analysis of the point light source was confirmed by a measurement that used the light source of a light-emitting diode. The sensitivity of the fiber-optic lever is inversely proportional to the fiber core radius, whereas the receiving light power is proportional to the number of illuminating and receiving fibers. Thus, the bundling of the finer fiber with the larger number of illuminating and receiving fibers is more effective for improving sensitivity and the displacement detection limit.

Polarisation of auroral emission lines in the Earth's upper atmosphere : first results and perspectives

NASA Astrophysics Data System (ADS)

Lamy, H.; Barthelemy, M.; Simon Wedlund, C.; Lilensten, J.; Bommier, V.

2011-12-01

Polarisation of light is a key observable to provide information about asymmetry or anisotropy within a radiative source. Following the pioneering and controversial work of Duncan in 1959, the polarisation of auroral emission lines in the Earth's upper atmosphere has been overlooked for a long time, even though the red intense auroral line (6300Å) produced by collisional impacts with electrons precipitating along magnetic field lines is a good candidate to search for polarisation. This problem was investigated again by Lilensten et al (2006) and observations were obtained by Lilensten et al (2008) confirming that the red auroral emission line is polarised. More recent measurements obtained by Barthélemy et al (2011) are presented and discussed. The results are compared to predictions of the theoretical work of Bommier et al (2011) and are in good agreement. Following these encouraging results, a new dedicated spectropolarimeter is currently under construction between BIRA-IASB and IPAG to provide simultaneously the polarisation of the red line and of other interesting auroral emission lines such as N2+ 1NG (4278Å), other N2 bands, etc... Perspectives regarding the theoretical polarisation of some of these lines will be presented. The importance of these polarisation measurements in the framework of atmospheric modeling and geomagnetic activity will be discussed.

Exploring synchrotron radiation capabilities: The ALS-Intel CRADA

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

Gozzo, F.; Cossy-Favre, A; Trippleet, B.

1997-04-01

Synchrotron radiation spectroscopy and spectromicroscopy were applied, at the Advanced Light Source, to the analysis of materials and problems of interest to the commercial semiconductor industry. The authors discuss some of the results obtained at the ALS using existing capabilities, in particular the small spot ultra-ESCA instrument on beamline 7.0 and the AMS (Applied Material Science) endstation on beamline 9.3.2. The continuing trend towards smaller feature size and increased performance for semiconductor components has driven the semiconductor industry to invest in the development of sophisticated and complex instrumentation for the characterization of microstructures. Among the crucial milestones established by themore » Semiconductor Industry Association are the needs for high quality, defect free and extremely clean silicon wafers, very thin gate oxides, lithographies near 0.1 micron and advanced material interconnect structures. The requirements of future generations cannot be met with current industrial technologies. The purpose of the ALS-Intel CRADA (Cooperative Research And Development Agreement) is to explore, compare and improve the utility of synchrotron-based techniques for practical analysis of substrates of interest to semiconductor chip manufacturing. The first phase of the CRADA project consisted in exploring existing ALS capabilities and techniques on some problems of interest. Some of the preliminary results obtained on Intel samples are discussed here.« less

Ion dynamics of a laser produced aluminium plasma at different ambient pressures

NASA Astrophysics Data System (ADS)

Sankar, Pranitha; Shashikala, H. D.; Philip, Reji

2018-01-01

Plasma is generated by pulsed laser ablation of an Aluminium target using 1064 nm, 7 ns Nd:YAG laser pulses. The spatial and temporal evolution of the whole plasma plume, as well as that of the ionic (Al2+) component present in the plume, are investigated using spectrally resolved time-gated imaging. The influence of ambient gas pressure on the expansion dynamics of Al2+ is studied in particular. In vacuum (10-5 Torr, 10-2 Torr) the whole plume expands adiabatically and diffuses into the ambient. For higher pressures in the range of 1-10 Torr plume expansion is in accordance with the shock wave model, while at 760 Torr the expansion follows the drag model. On the other hand, the expansion dynamics of the Al2+ component, measured by introducing a band pass optical filter in the detection system, fits to the shock wave model for the entire pressure range of 10-2 Torr to 760 Torr. The expansion velocities of the whole plume and the Al2+ component have been measured in vacuum. These dynamics studies are of potential importance for applications such as laser-driven plasma accelerators, ion acceleration, pulsed laser deposition, micromachining, laser-assisted mass spectrometry, ion implantation, and light source generation.

A CMB foreground study in WMAP data: Extragalactic point sources and zodiacal light emission

NASA Astrophysics Data System (ADS)

Chen, Xi

The Cosmic Microwave Background (CMB) radiation is the remnant heat from the Big Bang. It serves as a primary tool to understand the global properties, content and evolution of the universe. Since 2001, NASA's Wilkinson Microwave Anisotropy Probe (WMAP) satellite has been napping the full sky anisotropy with unprecedented accuracy, precision and reliability. The CMB angular power spectrum calculated from the WMAP full sky maps not only enables accurate testing of cosmological models, but also places significant constraints on model parameters. The CMB signal in the WMAP sky maps is contaminated by microwave emission from the Milky Way and from extragalactic sources. Therefore, in order to use the maps reliably for cosmological studies, the foreground signals must be well understood and removed from the maps. This thesis focuses on the separation of two foreground contaminants from the WMAP maps: extragalactic point sources and zodiacal light emission. Extragalactic point sources constitute the most important foreground on small angular scales. Various methods have been applied to the WMAP single frequency maps to extract sources. However, due to the limited angular resolution of WMAP, it is possible to confuse positive CMB excursions with point sources or miss sources that are embedded in negative CMB fluctuations. We present a novel CMB-free source finding technique that utilizes the spectrum difference of point sources and CMB to form internal linear combinations of multifrequency maps to suppress the CMB and better reveal sources. When applied to the WMAP 41, 64 and 94 GHz maps, this technique has not only enabled detection of sources that are previously cataloged by independent methods, but also allowed disclosure of new sources. Without the noise contribution from the CMB, this method responds rapidly with the integration time. The number of detections varies as 0( t 0.72 in the two-band search and 0( t 0.70 in the three-band search from one year to five years, separately, in comparison to t 0.40 from the WMAP catalogs. Our source catalogs are a good supplement to the existing WMAP source catalogs, and the method itself is proven to be both complementary to and competitive with all the current source finding techniques in WMAP maps. Scattered light and thermal emission from the interplanetary dust (IPD) within our Solar System are major contributors to the diffuse sky brightness at most infrared wavelengths. For wavelengths longer than 3.5 mm, the thermal emission of the IPD dominates over scattering, and the emission is often referred to as the Zodiacal Light Emission (ZLE). To set a limit of ZLE contribution to the WMAP data, we have performed a simultaneous fit of the yearly WMAP time-ordered data to the time variation of ZLE predicted by the DIRBE IPD model (Kelsallet al. 1998) evaluated at 240 mm, plus [cursive l] = 1 - 4 CMB components. It is found that although this fitting procedure can successfully recover the CMB dipole to a 0.5% accuracy, it is not sensitive enough to determine the ZLE signal nor the other multipole moments very accurately.

Behavioural responses of krill and cod to artificial light in laboratory experiments

PubMed Central

Løkkeborg, S.; Humborstad, O-B.

2018-01-01

Most fishes and crustaceans respond to light, and artificial light sources may therefore be an efficient stimulus to manipulate behaviours in aquatic animals. It has been hypothesised that the catch efficiency of pots could be increased if prey, for example krill, can be attracted into the pots providing a visual stimulus and a source of live bait. To find which light characteristics are most attractive to krill, we tested the effects of light intensity and wavelength composition on Northern krill’s (Meganyctiphanes norvegica) behavioural response to an artificial light source. The most attractive individual wavelength was 530 nm (green light), while broadband (425–750 nm) white light was an equally attractive light source. The intensity of the emitted light did not appear to have a direct effect on attraction to the light source, however it did significantly increase swimming activity among the observed krill. The most promising light stimuli for krill were tested to determine whether they would have a repulsive or attractive effect on cod (Gadus morhua); These light stimuli appeared to have a slightly repulsive, but non-significant, effect on cod. However, we suggest that a swarm of krill attracted to an artificial light source may produce a more effective visual stimulus to foraging cod. PMID:29370231

Behavioural responses of krill and cod to artificial light in laboratory experiments.

PubMed

Utne-Palm, A C; Breen, M; Løkkeborg, S; Humborstad, O-B

2018-01-01

Most fishes and crustaceans respond to light, and artificial light sources may therefore be an efficient stimulus to manipulate behaviours in aquatic animals. It has been hypothesised that the catch efficiency of pots could be increased if prey, for example krill, can be attracted into the pots providing a visual stimulus and a source of live bait. To find which light characteristics are most attractive to krill, we tested the effects of light intensity and wavelength composition on Northern krill's (Meganyctiphanes norvegica) behavioural response to an artificial light source. The most attractive individual wavelength was 530 nm (green light), while broadband (425-750 nm) white light was an equally attractive light source. The intensity of the emitted light did not appear to have a direct effect on attraction to the light source, however it did significantly increase swimming activity among the observed krill. The most promising light stimuli for krill were tested to determine whether they would have a repulsive or attractive effect on cod (Gadus morhua); These light stimuli appeared to have a slightly repulsive, but non-significant, effect on cod. However, we suggest that a swarm of krill attracted to an artificial light source may produce a more effective visual stimulus to foraging cod.

Performance of a novel multiple-signal luminescence sediment tracing method

NASA Astrophysics Data System (ADS)

Reimann, Tony

2014-05-01

Optically Stimulated Luminescence (OSL) is commonly used for dating sediments. Luminescence signals build up due to exposure of mineral grains to natural ionizing radiation, and are reset when these grains are exposed to (sun)light during sediment transport and deposition. Generally, luminescence signals can be read in two ways, potentially providing information on the burial history (dating) or the transport history (sediment tracing) of mineral grains. In this study we use a novel luminescence measurement procedure (Reimann et al., submitted) that simultaneously monitors six different luminescence signals from the same sub-sample (aliquot) to infer the transport history of sand grains. Daylight exposure experiments reveal that each of these six signals resets (bleaches) at a different rate, thus allowing to trace the bleaching history of the sediment in six different observation windows. To test the feasibility of luminescence sediment tracing in shallow-marine coastal settings we took eight sediment samples from the pilot mega-nourishment Zandmotor in Kijkduin (South-Holland). This site provides relatively controlled conditions as the morphological evolution of this nourishment is densely monitored (Stive et al., 2013). After sampling the original nourishment source we took samples along the seaward facing contour of the spit that was formed from August 2011 (start of nourishment) to June 2012 (sampling). It is presumed that these samples originate from the source and were transported and deposited within the first year after construction. The measured luminescence of a sediment sample was interpolated onto the daylight bleaching curve of each signal to assign the Equivalent Exposure Time (EET) to a sample. The EET is a quantitative measure of the full daylight equivalent a sample was exposed to during sediment transport, i.e. the higher the EET the longer the sample has been transported or the more efficient it has been exposed to day-light during sediment transport. The EET increases with increasing distance from the nourishment source, indicating that our method is capable to quantify sediment transport distances. We furthermore observed that the EET of an aeolian analogue is orders of magnitudes higher than those of the water-lain transported Zandmotor samples, suggesting that our approach is also able to differentiate between different modes of coastal sediment transport. This new luminescence approach offers new possibilities to decipher the sedimentation history of palaeo-environmental archives e.g. in coastal, fluvial or aeolian settings. References: Reimann, T.et al. Quantifying the degreeof bleaching during sediment transport using a polymineral multiple-signalluminescence approach. Submitted. Stive, M.J.F. et al. 2013. A New Alternative to Saving Our Beaches from Sea-Level Rise: The SandEngine. Journal of Coastal research 29, 1001-1008.

Quick photo-Fenton degradation of phenolic compounds by Cu/Al2O3-MCM-41 under visible light irradiation: small particle size, stabilization of copper, easy reducibility of Cu and visible light active material.

PubMed

Pradhan, Amaresh C; Nanda, Binita; Parida, K M; Das, Mira

2013-01-14

The present study reports the photo-Fenton degradation of phenolic compounds (phenol, 2-chloro-4-nitrophenol and 4-chloro-2-nitrophenol) in aqueous solution using mesoporous Cu/Al(2)O(3)-MCM-41 nanocomposite as a heterogeneous photo-Fenton-like catalyst. The in situ incorporation of mesoporous Al(2)O(3) (MA) into the framework of MCM-41 (sol-gel method) forms Al(2)O(3)-MCM-41 and wetness impregnation of Cu(II) on Al(2)O(3)-MCM-41 generates mesoporous Cu/Al(2)O(3)-MCM-41 composite. The effects of pH and H(2)O(2) concentration on degradation of phenol, 2-chloro-4-nitrophenol and 4-chloro-2-nitrophenol are studied. Kinetics analysis shows that the photocatalytic degradation reaction follows a first-order rate equation. Mesoporous 5 Cu/Al(2)O(3)-MCM-41 is found to be an efficient photo-Fenton-like catalyst for the degradation of phenolic compounds. It shows nearly 100% degradation in 45 min at pH 4. The combined effect of small particle size, stabilization of Cu(2+) on the support Al(2)O(3)-MCM-41, ease reducibility of Cu(2+) and visible light activeness are the key factors for quick degradation of phenolic compounds by Cu/Al(2)O(3)-MCM-41.

PHOTOMETRIC PROPERTIES OF SELECTED ALGOL-TYPE BINARIES. III. AL GEMINORUM AND BM MONOCEROTIS WITH POSSIBLE LIGHT-TIME ORBITS

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

Yang, Y.-G.; Dai, H.-F.; Li, H.-L., E-mail: yygcn@163.com

We present the CCD photometry of two Algol-type binaries, AL Gem and BM Mon, observed from 2008 November to 2011 January. With the updated Wilson-Devinney program, photometric solutions were deduced from their EA-type light curves. The mass ratios and fill-out factors of the primaries are found to be q{sub ph} = 0.090({+-} 0.005) and f{sub 1} = 47.3%({+-} 0.3%) for AL Gem, and q{sub ph} = 0.275({+-} 0.007) and f{sub 1} = 55.4%({+-} 0.5%) for BM Mon, respectively. By analyzing the O-C curves, we discovered that the periods of AL Gem and BM Mon change in a quasi-sinusoidal mode, whichmore » may possibly result from the light-time effect via the presence of a third body. Periods, amplitudes, and eccentricities of light-time orbits are 78.83({+-} 1.17) yr, 0fd0204({+-}0fd0007), and 0.28({+-} 0.02) for AL Gem and 97.78({+-} 2.67) yr, 0fd0175({+-}0fd0006), and 0.29({+-} 0.02) for BM Mon, respectively. Assumed to be in a coplanar orbit with the binary, the masses of the third bodies would be 0.29 M{sub Sun} for AL Gem and 0.26 M{sub Sun} for BM Mon. This kind of additional companion can extract angular momentum from the close binary orbit, and such processes may play an important role in multiple star evolution.« less

Photometric variability of the Be star population with the KELT survey

NASA Astrophysics Data System (ADS)

Labadie-Bartz, Jonathan; Pepper, Joshua; Chojnowski, S. Drew; McSwain, M. Virginia

2017-11-01

We are using light curves from the KELT exoplanet transit survey (Pepper et al. 2007) to study the variability of hundreds of Be stars. Combining these light curves with simultaneous time-series spectra from the APOGEE survey (Majewski et al. 2015) provides a glimpse into how changes in the circumstellar environment are correlated to brightness variations.

Science at the Time-scale of the Electron

NASA Astrophysics Data System (ADS)

Murnane, Margaret

2010-03-01

Replace this text with your abstract Ever since the invention of the laser 50 years ago and its application in nonlinear optics, scientists have been striving to extend coherent laser beams into the x-ray region of the spectrum. Very recently however, the prospects for tabletop coherent sources, with attosecond pulse durations, at very short wavelengths even in the hard x-ray region of the spectrum at wavelengths < 1nm, have brightened considerably. These advances are possible by taking nonlinear optics techniques to an extreme, and are the direct result of a new ability to manipulate electrons on the fastest, attosecond, time-scales of our natural world. My talk will discuss new experimental data that demonstrates high harmonic generation of laser-like, fully coherent, 10 attosecond duration, soft x-ray beams at photon energies around 0.5keV. Several applications will also be discussed, including making a movie of how electron orbitals in a molecule change shape as a molecule breaks apart, following how fast a magnetic material can flip orientation, understanding how fast heat flows in a nanocircuit, or building a microscope without lenses. [4pt] [1] T. Popmintchev et al., ``Phase matched upconversion of coherent ultrafast laser light into the soft and hard x-ray regions of the spectrum'', PNAS 106, 10516 (2009). [0pt] [2] C. LaOVorakiat et al., ``Ultrafast Soft X-Ray Magneto-Optics at the M-edge Using a Tabletop High-Harmonic Source'', Physical Review Letters 103, 257402 (2009). [0pt] [3] M. Siemens et al. ``Measurement of quasi-ballistic heat transport across nanoscale interfaces using ultrafast coherent soft x-ray beams'', Nature Materials 9, 26 (2010). [0pt] [4] K. Raines et al., ``Three-dimensional structure determination from a single view,'' Nature 463, 214 (2010). [0pt] [5] W. Li et al., ``Time-resolved Probing of Dynamics in Polyatomic Molecules using High Harmonic Generation'', Science 322, 1207 (2008).

High efficiency light source using solid-state emitter and down-conversion material

DOEpatents

Narendran, Nadarajah; Gu, Yimin; Freyssinier, Jean Paul

2010-10-26

A light emitting apparatus includes a source of light for emitting light; a down conversion material receiving the emitted light, and converting the emitted light into transmitted light and backward transmitted light; and an optic device configured to receive the backward transmitted light and transfer the backward transmitted light outside of the optic device. The source of light is a semiconductor light emitting diode, a laser diode (LD), or a resonant cavity light emitting diode (RCLED). The down conversion material includes one of phosphor or other material for absorbing light in one spectral region and emitting light in another spectral region. The optic device, or lens, includes light transmissive material.

Silicon micromachined broad band light source

NASA Technical Reports Server (NTRS)

George, Thomas (Inventor); Jones, Eric (Inventor); Tuma, Margaret L. (Inventor); Eastwood, Michael (Inventor); Hansler, Richard (Inventor)

2004-01-01

A micro electromechanical system (MEMS) broad band incandescent light source includes three layers: a top transmission window layer; a middle filament mount layer; and a bottom reflector layer. A tungsten filament with a spiral geometry is positioned over a hole in the middle layer. A portion of the broad band light from the heated filament is reflective off the bottom layer. Light from the filament and the reflected light of the filament are transmitted through the transmission window. The light source may operate at temperatures of 2500 K or above. The light source may be incorporated into an on board calibrator (OBC) for a spectrometer.

A two-metric proposal to specify the color-rendering properties of light sources for retail lighting

NASA Astrophysics Data System (ADS)

Freyssinier, Jean Paul; Rea, Mark

2010-08-01

Lighting plays an important role in supporting retail operations, from attracting customers, to enabling the evaluation of merchandise, to facilitating the completion of the sale. Lighting also contributes to the identity, comfort, and visual quality of a retail store. With the increasing availability and quality of white LEDs, retail lighting specifiers are now considering LED lighting in stores. The color rendering of light sources is a key factor in supporting retail lighting goals and thus influences a light source's acceptance by users and specifiers. However, there is limited information on what consumers' color preferences are, and metrics used to describe the color properties of light sources often are equivocal and fail to predict preference. The color rendering of light sources is described in the industry solely by the color rendering index (CRI), which is only indirectly related to human perception. CRI is intended to characterize the appearance of objects illuminated by the source and is increasingly being challenged because new sources are being developed with increasingly exotic spectral power distributions. This paper discusses how CRI might be augmented to better use it in support of the design objectives for retail merchandising. The proposed guidelines include the use of gamut area index as a complementary metric to CRI for assuring good color rendering.

Effect of laser speckle on light from laser diode-pumped phosphor-converted light sources.

PubMed

Aquino, Felipe; Jadwisienczak, Wojciech M; Rahman, Faiz

2017-01-10

Laser diode (LD) pumped white light sources are being developed as an alternative to light-emitting diode-pumped sources for high efficiency and/or high brightness applications. While several performance metrics of laser-pumped phosphor-converted light sources have been investigated, the effect of laser speckle has not been sufficiently explored. This paper describes our experimental studies on how laser speckle affects the behavior of light from laser-excited phosphor lamps. A single LD pumping a phosphor plate was the geometry explored in this work. Overall, our findings are that the down-converted light did not exhibit any speckle, whereas speckle was present in the residual pump light but much reduced from that in direct laser light. Furthermore, a thicker coating of small-grained phosphors served to effectively reduce speckle through static pump light diffusion in the phosphor coating. Our investigations showed that speckle is not of concern in illumination from LD-pumped phosphor-converted light sources.

P-doping-free III-nitride high electron mobility light-emitting diodes and transistors

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

Li, Baikui; Tang, Xi; Chen, Kevin J., E-mail: eekjchen@ust.hk

2014-07-21

We report that a simple metal-AlGaN/GaN Schottky diode is capable of producing GaN band-edge ultraviolet emission at 3.4 eV at a small forward bias larger than ∼2 V at room temperature. Based on the surface states distribution of AlGaN, a mature impact-ionization-induced Fermi-level de-pinning model is proposed to explain the underlying mechanism of the electroluminescence (EL) process. By experimenting with different Schottky metals, Ni/Au and Pt/Au, we demonstrated that this EL phenomenon is a “universal” property of metal-AlGaN/GaN Schottky diodes. Since this light-emitting Schottky diode shares the same active structure and fabrication processes as the AlGaN/GaN high electron mobility transistors, straight-forward andmore » seamless integration of photonic and electronic functional devices has been demonstrated on doping-free III-nitride heterostructures. Using a semitransparent Schottky drain electrode, an AlGaN/GaN high electron mobility light-emitting transistor is demonstrated.« less

Laser induced heat source distribution in bio-tissues

NASA Astrophysics Data System (ADS)

Li, Xiaoxia; Fan, Shifu; Zhao, Youquan

2006-09-01

During numerical simulation of laser and tissue thermal interaction, the light fluence rate distribution should be formularized and constituted to the source term in the heat transfer equation. Usually the solution of light irradiative transport equation is given in extreme conditions such as full absorption (Lambert-Beer Law), full scattering (Lubelka-Munk theory), most scattering (Diffusion Approximation) et al. But in specific conditions, these solutions will induce different errors. The usually used Monte Carlo simulation (MCS) is more universal and exact but has difficulty to deal with dynamic parameter and fast simulation. Its area partition pattern has limits when applying FEM (finite element method) to solve the bio-heat transfer partial differential coefficient equation. Laser heat source plots of above methods showed much difference with MCS. In order to solve this problem, through analyzing different optical actions such as reflection, scattering and absorption on the laser induced heat generation in bio-tissue, a new attempt was made out which combined the modified beam broaden model and the diffusion approximation model. First the scattering coefficient was replaced by reduced scattering coefficient in the beam broaden model, which is more reasonable when scattering was treated as anisotropic scattering. Secondly the attenuation coefficient was replaced by effective attenuation coefficient in scattering dominating turbid bio-tissue. The computation results of the modified method were compared with Monte Carlo simulation and showed the model provided reasonable predictions of heat source term distribution than past methods. Such a research is useful for explaining the physical characteristics of heat source in the heat transfer equation, establishing effective photo-thermal model, and providing theory contrast for related laser medicine experiments.

Evaluating white LEDs for outdoor landscape lighting application

NASA Astrophysics Data System (ADS)

Shakir, Insiya; Narendran, Nadarajah

2002-11-01

A laboratory experiment was conducted to understand the acceptability of different white light emitting diodes (LEDs) for outdoor landscape lighting. The study used a scaled model setup. The scene was designed to replicate the exterior of a typical upscale suburban restaurant including the exterior facade of the building, an approach with steps, and a garden. The lighting was designed to replicate light levels commonly found in nighttime outdoor conditions. The model had a central dividing partition with symmetrical scenes on both sides for side-by-side evaluations of the two scenes with different light sources. While maintaining equal luminance levels and distribution between the two scenes, four types of light sources were evaluated. These include, halogen, phosphor white LED, and two white light systems using RGB LEDs. These light sources were tested by comparing two sources at a time placed side-by-side and by individual assessment of each lighting condition. The results showed that the RGB LEDs performed equal or better than the most widely used halogen light source in this given setting. A majority of the subjects found slightly dimmer ambient lighting to be more typical for restaurants and therefore found RGB LED and halogen light sources to be more inviting. The phosphor white LEDs made the space look brighter, however a majority of the subjects disliked them.

The Orbital Period of the Classical Nova V458 Vul

NASA Astrophysics Data System (ADS)

Goranskij, V. P.; Metlova, N. V.; Barsukova, E. A.; Burenkov, A. N.; Soloviev, V. Ya.

2008-07-01

Classical nova V458 Vul (N Vul 2007 No.1) was detected as a supersoft X-ray source (SSS) by the Swift XRT several times in the time range between 2007 October 18 and 2008 June 18 (J. Drake et al., ATel #1246 and #1603). Our V photometry shows the plateau in the light curve continued since January till June 2008. This feature accompanies usually the SSS phases in some classical novae. The fragmentary monitoring during plateau shows night- to-night variability with the amplitudes between 1.2 and 0.4 mag and rapid variability by 0.1 mag in the time scale of an hour.

Mapping spiral structure on the far side of the Milky Way

NASA Astrophysics Data System (ADS)

Sanna, Alberto; Reid, Mark J.; Dame, Thomas M.; Menten, Karl M.; Brunthaler, Andreas

2017-10-01

Direct measurements of distances to astronomical sources rely on parallax, which can usually only be measured for relatively nearby objects. The far side of the Milky Way has been impossible to measure accurately, because the parallax is very small and interstellar dust blocks optical light from those regions. Sanna et al. used radio interferometry to directly determine the parallax distance to a star-forming region on the far side of the Galaxy. They also used a method of inferring distances from transverse motions, which produced the same answer. This allowed them to trace one of the Milky Way's spiral arms through almost an entire rotation.

Study on Formulation of Optimum Lighting-system for Purchasing Power at Stores

NASA Astrophysics Data System (ADS)

Fujita, Hiroki; Nakashima, Yoshio; Takamatsu, Mamoru; Oota, Masaaki; Sawa, Kazuhiro

In store lighting, difference in the look-and-feel of foods gives effects on the purchasing power of customers. This study conducted the digitalization and quantification on the effects of the variation of light-source color and illuminance used for lighting foods on image recognition on foods. As a result, it was clarified that when meat was illuminated with the light source of “pink” or “faint pink,” image evaluation on foods became higher. In addition, when illuminance increase was applied to these two light-source colors, image evaluation on “faint pink” became further higher. The reason is supposed to be that the redness of meat increased, which may have enhanced fresher impression. From this study, it has been clarified that the light-source color and illuminance optimum for each food are variant. The results show that lighting foods with the optimum light-source color and illuminance can make foods look better.

Light source comprising a common substrate, a first led device and a second led device

DOEpatents

Choong, Vi-En

2010-02-23

At least one stacked organic or polymeric light emitting diode (PLEDs) devices to comprise a light source is disclosed. At least one of the PLEDs includes a patterned cathode which has regions which transmit light. The patterned cathodes enable light emission from the PLEDs to combine together. The light source may be top or bottom emitting or both.

The Clinical Presentation and Management of Systemic Light-Chain Amyloidosis in China.

PubMed

Huang, Xiang-Hua; Liu, Zhi-Hong

2016-04-01

Amyloidosis includes a group of diseases characterized by the extracellular deposition of various fibrillary proteins that can autoaggregate in a highly abnormal fibrillary conformation. The amyloid precursor protein of systemic light-chain (AL) amyloidosis is comprised of monoclonal light chains that are due to plasma cell dyscrasia. The clinical presentation of patients with AL amyloidosis varies from patient to patient. Current treatment strategies target the clone in order to decrease the production of the pathologic light chains. Recent advances in therapy have helped many patients with AL amyloidosis achieve hematologic and organ responses. AL amyloidosis is the most common type of systemic amyloidosis in China with increasing morbidity and a high mortality rate. The clinical presentation of AL amyloidosis is variable, and the median overall survival was found to be 36.3 months. The disease prognosis and risk stratification are linked to serialized measurement of cardiac biomarkers and free light chains. The treatment of AL amyloidosis is mainly based on chemotherapy and autologous hematopoietic stem cell transplantation (ASCT). The use of novel agents (thalidomide, lenalidomide, and bortezomib) alone and in combination with steroids and alkylating agents has shown efficacy and continues to be explored. AL amyloidosis is the most common type of systemic amyloidosis in China with increasing morbidity and a high mortality rate. The lack of prospective clinical trials using the current therapies is a challenge for evidence-based decision making concerning the treatment of AL amyloidosis. (1) AL amyloidosis is the most prevalent type of amyloidosis accounting for 65% of the amyloidosis-diagnosed patients in the UK and for 93% of the amyloidosis-diagnosed patients in China. The predisposition of men over women to develop AL amyloidosis might be higher in China than in Western countries (2:1 vs. 1.3:1). Both in the East and West, incidence increases with age. At the time of diagnosis, edema is twice as frequent and the proportion of renal involvement is higher in Chinese compared to Western patients. (2) Melphalan followed by ASCT is the current standard therapy but is restricted to eligible patients. The efficacy and safety of bortezomib combined with dexamethasone were proven in Western patients and recently confirmed in a Chinese cohort. Recent studies in China and the US indicate that bortezomib induction prior to ASCT increases the response rate. Thalidomide and lenalidomide have shown benefit, but toxicity and lack of clinical evidence exclude these agents from first-line therapy. The green tea extract epigallocatechin-3-gallate is under investigation as an inhibitor of AL amyloid formation and a compound that might dissolve amyloid.

DUV light source availability improvement via further enhancement of gas management technologies

NASA Astrophysics Data System (ADS)

Riggs, Daniel J.; O'Brien, Kevin; Brown, Daniel J. W.

2011-04-01

The continuous evolution of the semiconductor market necessitates ever-increasing improvements in DUV light source uptime as defined in the SEMI E10 standard. Cymer is developing technologies to exceed current and projected light source availability requirements via significant reduction in light source downtime. As an example, consider discharge chamber gas management functions which comprise a sizable portion of DUV light source downtime. Cymer's recent introduction of Gas Lifetime Extension (GLXTM) as a productivity improvement technology for its DUV lithography light sources has demonstrated noteworthy reduction in downtime. This has been achieved by reducing the frequency of full gas replenishment events from once per 100 million pulses to as low as once per 2 billion pulses. Cymer has continued to develop relevant technologies that target further reduction in downtime associated with light source gas management functions. Cymer's current subject is the development of technologies to reduce downtime associated with gas state optimization (e.g. total chamber gas pressure) and gas life duration. Current gas state optimization involves execution of a manual procedure at regular intervals throughout the lifetime of light source core components. Cymer aims to introduce a product enhancement - iGLXTM - that eliminates the need for the manual procedure and, further, achieves 4 billion pulse gas lives. Projections of uptime on DUV light sources indicate that downtime associated with gas management will be reduced by 70% when compared with GLX2. In addition to reducing downtime, iGLX reduces DUV light source cost of operation by constraining gas usage. Usage of fluorine rich Halogen gas mix has been reduced by 20% over GLX2.

Design and evaluation of excitation light source device for fluorescence endoscope

NASA Astrophysics Data System (ADS)

Lim, Hyun Soo

2009-06-01

This study aims at designing and evaluating light source devices that can stably generate light with various wavelengths in order to make possible PDD using a photosensitizer and diagnosis using auto-fluorescence. The light source was a Xenon lamp and filter wheel, composed of an optical output control through Iris and filters with several wavelength bands. It also makes the inducement of auto-fluorescence possible because it is designed to generate a wavelength band of 380-420nm, 430-480nm, and 480-560nm. The transmission part of the light source was developed to enhance the efficiency of light transmission. To evaluate this light source, the characteristics of light output and wavelength band were verified. To validate the capability of this device as PDD, the detection of auto-fluorescence using mouse models was performed.

Modeling of an Adjustable Beam Solid State Light Project

NASA Technical Reports Server (NTRS)

Clark, Toni

2015-01-01

This proposal is for the development of a computational model of a prototype variable beam light source using optical modeling software, Zemax Optics Studio. The variable beam light source would be designed to generate flood, spot, and directional beam patterns, while maintaining the same average power usage. The optical model would demonstrate the possibility of such a light source and its ability to address several issues: commonality of design, human task variability, and light source design process improvements. An adaptive lighting solution that utilizes the same electronics footprint and power constraints while addressing variability of lighting needed for the range of exploration tasks can save costs and allow for the development of common avionics for lighting controls.

Stacking multiple connecting functional materials in tandem organic light-emitting diodes

PubMed Central

Zhang, Tao; Wang, Deng-Ke; Jiang, Nan; Lu, Zheng-Hong

2017-01-01

Tandem device is an important architecture in fabricating high performance organic light-emitting diodes and organic photovoltaic cells. The key element in making a high performance tandem device is the connecting materials stack, which plays an important role in electric field distribution, charge generation and charge injection. For a tandem organic light-emitting diode (OLED) with a simple Liq/Al/MoO3 stack, we discovered that there is a significant current lateral spreading causing light emission over an extremely large area outside the OLED pixel when the Al thickness exceeds 2 nm. This spread light emission, caused by an inductive electric field over one of the device unit, limits one’s ability to fabricate high performance tandem devices. To resolve this issue, a new connecting materials stack with a C60 fullerene buffer layer is reported. This new structure permits optimization of the Al metal layer in the connecting stack and thus enables us to fabricate an efficient tandem OLED having a high 155.6 cd/A current efficiency and a low roll-off (or droop) in current efficiency. PMID:28225028

Stacking multiple connecting functional materials in tandem organic light-emitting diodes

NASA Astrophysics Data System (ADS)

Zhang, Tao; Wang, Deng-Ke; Jiang, Nan; Lu, Zheng-Hong

2017-02-01

Tandem device is an important architecture in fabricating high performance organic light-emitting diodes and organic photovoltaic cells. The key element in making a high performance tandem device is the connecting materials stack, which plays an important role in electric field distribution, charge generation and charge injection. For a tandem organic light-emitting diode (OLED) with a simple Liq/Al/MoO3 stack, we discovered that there is a significant current lateral spreading causing light emission over an extremely large area outside the OLED pixel when the Al thickness exceeds 2 nm. This spread light emission, caused by an inductive electric field over one of the device unit, limits one’s ability to fabricate high performance tandem devices. To resolve this issue, a new connecting materials stack with a C60 fullerene buffer layer is reported. This new structure permits optimization of the Al metal layer in the connecting stack and thus enables us to fabricate an efficient tandem OLED having a high 155.6 cd/A current efficiency and a low roll-off (or droop) in current efficiency.

Multichannel Luminescence Properties of Mixed-Valent Eu2+/Eu3+ Coactivated SrAl3BO7 Nanocrystalline Phosphors for Near-UV LEDs.

PubMed

Liu, Xiaoming; Xie, Weijie; Lü, Ying; Feng, Jingchun; Tang, Xinghua; Lin, Jun; Dai, Yuhua; Xie, Yu; Yan, Liushui

2017-11-20

Up to now, orchestrating the coexistence of Eu 2+ and Eu 3+ activators in a single host lattice has been an extremely difficult task, especially for the appearance of the characteristic emission of Eu 2+ and Eu 3+ in order to generate white light. Nevertheless, here we demonstrate a new Eu 2+ /Eu 3+ coactivated SrAl 3 BO 7 nanocrystalline phosphor with abundant and excellent multichannel luminescence properties. A series of Eu 2+ /Eu 3+ coactivated SrAl 3 BO 7 nanocrystalline phosphors were prepared through a Pechini-type sol-gel method followed by a reduction process. With excitation of UV/NUV light, the prepared SrAl 3 BO 7 :Eu 2+ ,Eu 3+ phosphors show not only the characteristic f-f transitions of Eu 3+ ion ( 5 D J → 7 F J,J' , J, J' = 0-3), but also the 5d → 4f transitions of Eu 2+ ion with comparable intensity from 400 to 700 nm in the whole visible spectral region. The luminescence color of the SrAl 3 BO 7 :Eu 2+ ,Eu 3+ phosphor can be tuned from blue, blue-green, white, and orange to orange-red by changing the excitation wavelength, the overall doping concentration of europium ions (Eu 2+ , Eu 3+ ), and the relative ratio of Eu 2+ to Eu 3+ ions to some extent. A single-phase white-light emission has been realized in SrAl 3 BO 7 :Eu 2+ ,Eu 3+ phosphor. The obtained SrAl 3 BO 7 :Eu 2+ ,Eu 3+ phosphor has potential application in the area of NUV white-light-emitting diodes.

Surface plasmon coupling for suppressing p-GaN absorption and TM-polarized emission in a deep-UV light-emitting diode.

PubMed

Kuo, Yang; Su, Chia-Ying; Hsieh, Chieh; Chang, Wen-Yen; Huang, Chu-An; Kiang, Yean-Woei; Yang, C C

2015-09-15

The radiated power enhancement (suppression) of an in- (out-of-) plane-oriented radiating dipole at a desired emission wavelength in the deep-ultraviolet (UV) range when it is coupled with a surface plasmon (SP) resonance mode induced on a nearby Al nanoparticle (NP) is demonstrated. Also, it is found that the enhanced radiated power propagates mainly in the direction from the Al NP toward the dipole. Such SP coupling behaviors can be used for suppressing the transverse-magnetic (TM)-polarized emission, enhancing the transverse-electric-polarized emission, and reducing the UV absorption of the p-GaN layer in an AlGaN-based deep-UV light-emitting diode by embedding a sphere-like Al NP in its p-AlGaN layer.

An experiment on the color rendering of different light sources

NASA Astrophysics Data System (ADS)

Fumagalli, Simonetta; Bonanomi, Cristian; Rizzi, Alessandro

2013-02-01

The color rendering index (CRI) of a light source attempts to measure how much the color appearance of objects is preserved when they are illuminated by the given light source. This problem is of great importance for various industrial and scientific fields, such as lighting architecture, design, ergonomics, etc. Usually a light source is specified through the Correlated Color Temperature or CCT. However two (or more) light sources with the same CCT but different spectral power distribution can exist. Therefore color samples viewed under two light sources with equal CCTs can appear different. Hence, the need for a method to assess the quality of a given illuminant in relation to color. Recently CRI has had a renewed interest because of the new LED-based lighting systems. They usually have a color rendering index rather low, but good preservation of color appearance and a pleasant visual appearance (visual appeal). Various attempts to develop a new color rendering index have been done so far, but still research is working for a better one. This article describes an experiment performed by human observers concerning the appearance preservation of color under some light sources, comparing it with a range of available color rendering indices.

EGR distribution and fluctuation probe based on CO.sub.2 measurements

DOEpatents

Parks, II, James E; Partridge, Jr., William P; Yoo, Ji Hyung

2015-04-07

A diagnostic system having a single-port EGR probe and a method for using the same. The system includes a light source, an EGR probe, a detector and a processor. The light source may provide a combined light beam composed of light from a mid-infrared signal source and a mid-infrared reference source. The signal source may be centered at 4.2 .mu.m and the reference source may be centered at 3.8 .mu.m. The EGR probe may be a single-port probe with internal optics and a sampling chamber with two flow cells arranged along the light path in series. The optics may include a lens for focusing the light beam and a mirror for reflecting the light beam received from a pitch optical cable to a catch optical cable. The signal and reference sources are modulated at different frequencies, thereby allowing them to be separated and the signal normalized by the processor.

Synchrotron Light Sources in Developing Countries

NASA Astrophysics Data System (ADS)

Winick, Herman; Pianetta, Piero

The more than 50 light sources in operation include facilities in Brazil, Korea, and Taiwan which started in the 1980's when they were developing countries. They came on line in the 1990's and have since trained hundreds of graduate students. They have attracted mid-career diaspora scientists to return. Growing user communities have demanded more advanced facilities, leading to higher performance new light sources that are now coming into operation. Light sources in the developing world now include the following: ∖textbf{SESAME}in the Middle East which is scheduled to start research in 2017 (∖underline {www.sesame.org}); ∖textbf{The African Light Source}, in the planning stage (∖underline {www.safricanlightsource.org}); and ∖textbf{The Mexican Light Source}, in the planning stage (∖underline {http://www.aps.org/units/fip/newsletters/201509/mexico.cfm}). See: http://wpj.sagepub.com/content/32/4/92.full.pdf +html; http://www.lightsources.org/press-release/2015/11/20/grenoble-resolutions-mark-historical-step-towards-african-light-source..

Reduction of background clutter in structured lighting systems

DOEpatents

Carlson, Jeffrey J.; Giles, Michael K.; Padilla, Denise D.; Davidson, Jr., Patrick A.; Novick, David K.; Wilson, Christopher W.

2010-06-22

Methods for segmenting the reflected light of an illumination source having a characteristic wavelength from background illumination (i.e. clutter) in structured lighting systems can comprise pulsing the light source used to illuminate a scene, pulsing the light source synchronously with the opening of a shutter in an imaging device, estimating the contribution of background clutter by interpolation of images of the scene collected at multiple spectral bands not including the characteristic wavelength and subtracting the estimated background contribution from an image of the scene comprising the wavelength of the light source and, placing a polarizing filter between the imaging device and the scene, where the illumination source can be polarized in the same orientation as the polarizing filter. Apparatus for segmenting the light of an illumination source from background illumination can comprise an illuminator, an image receiver for receiving images of multiple spectral bands, a processor for calculations and interpolations, and a polarizing filter.

A Historical Approach to the Teaching of the Linear Propagation of Light, Shadows and Pinhole Cameras

ERIC Educational Resources Information Center

Mihas, Pavlos; Andreadis, Panagiotis

2005-01-01

In this paper are presented the views of Al Haytham and his predecessors on the shadows, the rectilinear propagation of rays and the images produced by pinholes. Al Haytham had given erroneous views on the distribution of light in the shadows. Educational applications of these are presented. These applications concern: (a) Simple experiments (b)…

Polymer Solar Cells with 90% External Quantum Efficiency Featuring an Ideal Light- and Charge-Manipulation Layer.

PubMed

Chen, Jing-De; Li, Yan-Qing; Zhu, Jingshuai; Zhang, Qianqian; Xu, Rui-Peng; Li, Chi; Zhang, Yue-Xing; Huang, Jing-Sheng; Zhan, Xiaowei; You, Wei; Tang, Jian-Xin

2018-03-01

Rapid progress in the power conversion efficiency (PCE) of polymer solar cells (PSEs) is beneficial from the factors that match the irradiated solar spectrum, maximize incident light absorption, and reduce photogenerated charge recombination. To optimize the device efficiency, a nanopatterned ZnO:Al 2 O 3 composite film is presented as an efficient light- and charge-manipulation layer (LCML). The Al 2 O 3 shells on the ZnO nanoparticles offer the passivation effect that allows optimal electron collection by suppressing charge-recombination loss. Both the increased refractive index and the patterned deterministic aperiodic nanostructure in the ZnO:Al 2 O 3 LCML cause broadband light harvesting. Highly efficient single-junction PSCs for different binary blends are obtained with a peak external quantum efficiency of up to 90%, showing certified PCEs of 9.69% and 13.03% for a fullerene blend of PTB7:PC 71 BM and a nonfullerene blend, FTAZ:IDIC, respectively. Because of the substantial increase in efficiency, this method unlocks the full potential of the ZnO:Al 2 O 3 LCML toward future photovoltaic applications. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Light Source Matters--Students' Explanations about the Behavior of Light When Different Light Sources Are Used in Task Assignments of Optics

ERIC Educational Resources Information Center

Kesonen, Mikko Henri Petteri; Asikainen, Mervi Anita; Hirvonen, Pekka Emil

2017-01-01

In the present article, the context-dependency of student reasoning is studied in a context of optics. We investigated introductory students' explanations about the behavior of light when different light sources, namely a small light bulb and a laser, were used in otherwise identical task assignments. The data was gathered with the aid of pretest…

Color tunable light-emitting diodes based on p+-Si/p-CuAlO2/n-ZnO nanorod array heterojunctions

NASA Astrophysics Data System (ADS)

Ling, Bo; Zhao, Jun Liang; Sun, Xiao Wei; Tan, Swee Tiam; Kyaw, Aung Ko Ko; Divayana, Yoga; Dong, Zhi Li

2010-07-01

Wide-range color tuning from red to blue was achieved in phosphor-free p+-Si/p-CuAlO2/n-ZnO nanorod light-emitting diodes at room temperature. CuAlO2 films were deposited on p+-Si substrates by sputtering followed by annealing. ZnO nanorods were further grown on the annealed p+-Si/p-CuAlO2 substrates by vapor phase transport. The color of the p-CuAlO2/n-ZnO nanorod array heterojunction electroluminescence depended on the annealing temperature of the CuAlO2 film. With the increase of the annealing temperature from 900 to 1050 °C, the emission showed a blueshift under the same forward bias. The origin of the blueshift is related to the amount of Cu concentration diffused into ZnO.

Microelectromechanical Systems (MEMS) Broadband Light Source Developed

NASA Technical Reports Server (NTRS)

Tuma, Margaret L.

2003-01-01

A miniature, low-power broadband light source has been developed for aerospace applications, including calibrating spectrometers and powering miniature optical sensors. The initial motivation for this research was based on flight tests of a Fabry-Perot fiberoptic temperature sensor system used to detect aircraft engine exhaust gas temperature. Although the feasibility of the sensor system was proven, the commercial light source optically powering the device was identified as a critical component requiring improvement. Problems with the light source included a long stabilization time (approximately 1 hr), a large amount of heat generation, and a large input electrical power (6.5 W). Thus, we developed a new light source to enable the use of broadband optical sensors in aerospace applications. Semiconductor chip-based light sources, such as lasers and light-emitting diodes, have a relatively narrow range of emission wavelengths in comparison to incandescent sources. Incandescent light sources emit broadband radiation from visible to infrared wavelengths; the intensity at each wavelength is determined by the filament temperature and the materials chosen for the filament and the lamp window. However, present commercial incandescent light sources are large in size and inefficient, requiring several watts of electrical power to obtain the desired optical power, and they emit a large percentage of the input power as heat that must be dissipated. The miniature light source, developed jointly by the NASA Glenn Research Center, the Jet Propulsion Laboratory, and the Lighting Innovations Institute, requires one-fifth the electrical input power of some commercial light sources, while providing similar output light power that is easily coupled to an optical fiber. Furthermore, it is small, rugged, and lightweight. Microfabrication technology was used to reduce the size, weight, power consumption, and potential cost-parameters critical to future aerospace applications. This chip-based light source has the potential for monolithic fabrication with on-chip drive electronics. Other uses for these light sources are in systems for vehicle navigation, remote sensing applications such as monitoring bridges for stress, calibration sources for spectrometers, light sources for space sensors, display lighting, addressable arrays, and industrial plant monitoring. Two methods for filament fabrication are being developed: wet-chemical etching and laser ablation. Both yield a 25-mm-thick tungsten spiral filament. The proof-of-concept filament shown was fabricated with the wet etch method. Then it was tested by heating it in a vacuum chamber using about 1.25 W of electrical power; it generated bright, blackbody radiation at approximately 2650 K. The filament was packaged in Glenn's clean-room facilities. This design uses three chips vacuum-sealed with glass tape. The bottom chip consists of a reflective film deposited on silicon, the middle chip contains a tungsten filament bonded to silicon, and the top layer is a transparent window. Lifetime testing on the package will begin shortly. The emitted optical power is expected to be approximately 1.0 W with the spectral peak at 1.1 mm.

Observation of solar-system objects with the ISO satellite

NASA Astrophysics Data System (ADS)

Encrenaz, Therese

1998-09-01

The ISO (Infrared Space Observatory) mission was an ESA earth-orbiting satellite devoted to the infrared observation of astronomical sources. The 60-cm helium-cooled telescope was launched in November 1995 and ended its life in May 1998. The satellite was equipped with 4 focal-plane instruments: a camera (CAM, 2.5-17 microns), a photometer (PHT, 2-200 microns) and two spectrometers, SWS (2.3-45 microns) and LWS (45-180 microns). A description of the ISO mission can be found in Kessler et al.(A&A 315 L27, 1996). Observations with ISO have been performed on all classes of solar-system objects. Several important discoveries have been obtained from the ISO data, in particular with the SWS instrument. A few of them are listed below: (1) a new determination of D/H on the four giant planets; (2) the discovery of an external source of water in the stratospheres of the giant planets and Titan; (3) the detection of CO_2 in the stratospheres of Jupiter, Saturn and Neptune; (4) the detection of new hydrocarbons (CH_3C_2H, C_4H_2, C_6H_6, CH_3) in Saturn's stratosphere; (5) the detection of tropospheric water in Saturn; (6) the detection of CO_2 in comet Hale-Bopp at far heliocentric distances (4.6 AU); (7) the first detection of forsterite (Mg_2SiO_4) in the dust of comet Hale-Bopp; (7) the determination of the formation temperature of comets Hale-Bopp and Hartley 2 (27 K and 35 K respectively) from the measurement of the ortho-para ratio in their H_2O nu _3 emission lines. In addition, ISO spectra of Titan, Io and the other galilean satellites, and asteroids were also recorded; IR photometry was achieved on Pluto, distant comets and zodiacal light. Preliminary results can be found in Crovisier et al. (A&A 315 L385, 1996; Science 275 1904, 1996), Encrenaz et al. (A&A 315 L397, 1996; A&A 333 L43, 1998), de Graauw et al. (A&A 321 L13, 1997), Feuchtgruber et al. (Nature 389 159, 1997), Griffin et al. (A&A 315 L389, 1996), Davis et al. (A&A 315 L393, 1996), Reach et al. (A&A 315 L381, 1996), Bezard et al. (A&A 334 L41, 1998) and Coustenis et al. (A&A 336 L85, 1998).

Equatorial Layered Deposits in Arabia Terra, Mars: Facies and Process Variability

NASA Astrophysics Data System (ADS)

Pondrelli, M.; Rossi, A.; van Gasselt, S.; Le Deit, L.; Glamoclija, M.; Cavalazzi, B.; Franchi, F.; Fueten, F.; Hauber, E.; Zegers, T.

2012-12-01

Genetic mechanisms proposed to explain Equatorial Layered Deposits (ELDs) formation include subglacial volcanism, aeolian/airfall, lacustrine, lacustrine/volcanic and spring-fed deposition. ELDs have been frequently shown to consist of sulfates (e.g. Gendrin et al., 2005) that might form as a response to evaporation in a playa environment (Hoefen et al., 2003) or during spring precipitation (e.g. Allen and Oehler, 2008; Rossi et al., 2008). The importance of groundwater-dominated hydrological systems was proposed to explain the formation of light-toned deposits in Meridiani Planum and Arabia Terra (e.g. Andrews-Hanna et al. 2007). Additionally, fluid expulsion processes have been invoked to explain the formation of mounds within the light-toned deposits in Arabia Terra (Allen and Oehler, 2008; Rossi et al., 2008; Pondrelli et al., 2011). Potential for habitable conditions of both playa and spring-related settings (Cavalazzi et al., 2007; Glamoclija et al., 2011) coupled with the high preservation potential within sulfates (Panieri et al., 2010), make these deposits a good candidate to understand the potential past habitability of the planet. In order to investigate ELDs genesis, an area in the vicinity of Firsoff crater, where ELDs are present within and outside the craters, was selected for geological mapping and analysis of the landforms and their association using the available dataset, including CRISM in order to infer ELDs composition. Within Firsoff crater, ELDs form a bulge that can be estimated to be at least a few hundred meters thick, while, outside the craters, ELDs form flat-lying deposits. Although heavily eroded by wind and carved by yardangs, several morphologies within the ELDs in the craters seem to be depositional, which would exclude that the entire Firsoff basin had been originally filled by ELDs. Within craters, ELDs consist of roughly meter thick layers draping and onlapping the substratum. They appear affected by polygonal patterns with no evidence of sedimentary structures. Polyhydrated sulfates have been detected. At places, ELDs appear to be linked to and possibly sourced from tectonically controlled lineaments. Large cone-shaped mounds (100 to 500 m) are situated locally on top of ELDs. They consist of boulders embedded in a matrix, and about one-third of them display an orifice at their top. Outside of the craters, ELDs show large-scale cross stratification associated to duneforms, which suggests an aeolian origin possibly associated to playa deposits. We distinguish between fluid expulsion ELDs forming within the crater and aeolian ELDs outside and possibly inside the craters. Fluid expulsion ELDs would result from groundwater upwelling and following evaporitic precipitation, whereas aeolian ELDs would result from reworking and redeposition of the spring ELDs. References Allen and Oehler (2008), Astrobiology, 8, 1093-1112. Andrews-Hanna et al. (2007), Nature, 446, 163-166. Cavalazzi et al. (2007), Sed. Geol., 200, 73-88. Gendrin et al. (2005), Science, 307, 1587. Glamoclija et al. (2011), Geomicrob. J., 29, 733-751. Hoefen et al. (2003), Science, 302, 627-630. Panieri et al. (2010), Geobiology, 8, 101-111. Pondrelli et al. (2011), EPSL, 304, 511-519. Rossi et al. (2008), JGR, 113(8).

Internal quantum efficiency in yellow-amber light emitting AlGaN-InGaN-GaN heterostructures

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

Ngo, Thi Huong; Gil, Bernard; Valvin, Pierre

2015-09-21

We determine the internal quantum efficiency of strain-balanced AlGaN-InGaN-GaN hetero-structures designed for yellow-amber light emission, by using a recent model based on the kinetics of the photoluminescence decay initiated by Iwata et al. [J. Appl. Phys. 117, 075701 (2015)]. Our results indicate that low temperature internal quantum efficiencies sit in the 50% range and we measure that adding an AlGaN layer increases the internal quantum efficiency from 50% up to 57% with respect to the GaN-InGaN case. More dramatic, it almost doubles from 2.5% up to 4.3% at room temperature.

Applications of Slow Light in Telecommunications

DTIC Science & Technology

2006-04-01

that the distortion of the transmitted waveform can be dramatically reduced by using frequency-flattened gain profiles [ Stenner et al.]. Time [ns...Express 13, 7872 (2005). >> K.Y. Song et al. Opt. Express 13, 83 (2005). >> M.D. Stenner et al. Opt. Express 13, 9995 (2005). >> X. Zhao et al. Opt

[Histopathological diagnosis of amyloidosis].

PubMed

Hoshii, Yoshinobu

2006-05-01

For the diagnosis of amyloidosis, histological evidence of amyloid deposition is essential. Histologically, an amyloid deposit is stained orange red with Congo red and shows green birefringence under polarized light. When amyloidosis is clinically suspected, endoscopic biopsy of the stomach, duodenum or colon, or aspiration biopsy of abdominal fat is usually performed. If clinicians suspect amyloidosis, they should advise pathologists. Identification of the chemical type of amyloid is necessary with respect to treatment and prognosis. Immunohistochemical examination of amyloid in formalin-fixed, paraffin-embedded sections is simple to perform in most pathological laboratories. In Japan, almost all cases of systemic amyloidosis are classified as AL, AA, ATTR or Abeta2M amyloidosis, so the use of anti-immunoglobulin light chain, anti-amyloid A, anti-transthyretin and anti-beta2 microglobulin antibody is recommended for the classification of systemic amyloidosis. Formic acid pretreatment, which is often used for immunohistochemical detection of amyloidosis, is useful and easy for antigen retrieval. Amyloid deposits of AL amyloidosis are sometimes not immunostained well with commercial anti-immunoglobulin light chain antibody. Previously, we generated polyclonal antibodies against synthetic peptides corresponding to positions 118-134 of immunoglobulin lambda light chain and positions 116-133 of immunoglobulin kappa light chain. These antibodies are very useful for detecting AL amyloidosis because they react with amyloid deposits on formalin-fixed, paraffin-embedded specimens in almost all AL amyloidosis cases. Exact diagnosis and typing of amyloidosis are necessary for therapy.

A compact high brightness laser synchrotron light source for medical applications

NASA Astrophysics Data System (ADS)

Nakajima, Kazuhisa

1999-07-01

The present high-brightness hard X-ray sources have been developed as third generation synchrotron light sources based on large high energy electron storage rings and magnetic undulators. Recently availability of compact terawatt lasers arouses a great interest in the use of lasers as undulators. The laser undulator concept makes it possible to construct an attractive compact synchrotron radiation source which has been proposed as a laser synchrotron light source. This paper proposes a compact laser synchrotron light source for mediacal applications, such as an intravenous coronary angiography and microbeam therapy.

Ground deposition of liquid droplets released from a point source in the atmospheric surface layer

NASA Astrophysics Data System (ADS)

Panneton, Bernard

1989-01-01

A series of field experiments is presented in which the ground deposition of liquid droplets, 120 and 150 microns in diameter, released from a point source at 7 m above ground level, was measured. A detailed description of the experimental technique is provided, and the results are presented and compared to the predictions of a few models. A new rotating droplet generator is described. Droplets are produced by the forced breakup of capillary liquid jets and droplet coalescence is inhibited by the rotational motion of the spray head. The two dimensional deposition patterns are presented in the form of plots of contours of constant density, normalized arcwise distributions and crosswind integrated distributions. The arcwise distributions follow a Gaussian distribution whose standard deviation is evaluated using a modified Pasquill's technique. Models of the crosswind integrated deposit from Godson, Csanady, Walker, Bache and Sayer, and Wilson et al are evaluated. The results indicate that the Wilson et al random walk model is adequate for predicting the ground deposition of the 150 micron droplets. In one case, where the ratio of the droplet settling velocity to the mean wind speed was largest, Walker's model proved to be adequate. Otherwise, none of the models were acceptable in light of the experimental data.

Instrumental and bio-monitoring of heavy metal and nanoparticle emissions from diesel engine exhaust in controlled environment.

PubMed

Giordano, Simonetta; Adamo, Paola; Spagnuolo, Valeria; Vaglieco, Bianca Maria

2010-01-01

In the present article we characterized the emissions at the exhaust of a Common Rail (CR) diesel engine, representative of light-duty class, equipped with a catalyzed diesel particulate filter (CDPF) in controlled environment. The downstream exhausts were directly analyzed (for PM, CO, CO2, 02, HCs, NOx) by infrared and electrochemical sensors, and SEM-EDS microscope; heavy metals were chemically analyzed using mosses and lichens in bags, and glass-fibre filters all exposed at the engine exhausts. The highest particle emission value was in the 7-54 nm size range; the peak concentration rose until one order of magnitude for the highest load and speed. Particle composition was mainly carbonaceous, associated to noticeable amounts of Fe and silica fibres. Moreover, the content of Cu, Fe, Na, Ni and Zn in both moss and lichen, and of Al and Cr in moss, was significantly increased. Glass-fibre filters were significantly enriched in Al, B, Ba, Cu, Fe, Na, and Zn. The role of diesel engines as source of carbonaceous nanoparticles has been confirmed, while further investigations in controlled environment are needed to test the catalytic muffler as a possible source of silica fibres considered very hazardous for human health.

2A4 binds soluble and insoluble light chain aggregates from AL amyloidosis patients and promotes clearance of amyloid deposits by phagocytosis †

PubMed Central

Renz, Mark; Torres, Ronald; Dolan, Philip J.; Tam, Stephen J.; Tapia, Jose R.; Li, Lauri; Salmans, Joshua R.; Barbour, Robin M.; Shughrue, Paul J.; Nijjar, Tarlochan; Schenk, Dale; Kinney, Gene G.; Zago, Wagner

2016-01-01

Abstract Amyloid light chain (AL) amyloidosis is characterized by misfolded light chain (LC) (amyloid) deposition in various peripheral organs, leading to progressive dysfunction and death. There are no regulatory agency–approved treatments for AL amyloidosis, and none of the available standard of care approaches directly targets the LC protein that constitutes the amyloid. NEOD001, currently in late-stage clinical trials, is a conformation-specific, anti-LC antibody designed to specifically target misfolded LC aggregates and promote phagocytic clearance of AL amyloid deposits. The present study demonstrated that the monoclonal antibody 2A4, the murine form of NEOD001, binds to patient-derived soluble and insoluble LC aggregates and induces phagocytic clearance of AL amyloid in vitro. 2A4 specifically labeled all 21 fresh-frozen organ samples studied, which were derived from 10 patients representing both κ and λ LC amyloidosis subtypes. 2A4 immunoreactivity largely overlapped with thioflavin T–positive labeling, and 2A4 bound both soluble and insoluble LC aggregates extracted from patient tissue. Finally, 2A4 induced macrophage engagement and phagocytic clearance of AL amyloid deposits in vitro. These findings provide further evidence that 2A4/NEOD001 can effectively clear and remove human AL-amyloid from tissue and further support the rationale for the evaluation of NEOD001 in patients with AL amyloidosis. PMID:27494229

Near white light emitting ZnAl{sub 2}O{sub 4}:Dy{sup 3+} nanocrystals: Sol–gel synthesis and luminescence studies

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

Kumar, Mithlesh, E-mail: mithlesh@barc.gov.in; Gupta, Santosh K.; Kadam, R.M.

2016-02-15

Highlights: • ZnAl{sub 2}O{sub 4}:Dy{sup 3+} spinel synthesized using sol–gel method. • Characterized by XRD, SEM and PL spectroscopy. • Investigations of emission, excitation and lifetime properties. • Evaluation of defect centers and trap parameters of the system. • Evaluation of CIE indices of near white light emitting phosphor. - Abstract: ZnAl{sub 2}O{sub 4}:Dy{sup 3+} nanoparticles were synthesized using citrate sol–gel method and characterized systematically using X-ray diffraction, scanning electron microscopy and photoluminescence spectroscopy. Emission spectrum of pure ZnAl{sub 2}O{sub 4} shows intense violet blue emission under ultra violet irradiation. Based on electron paramagnetic resonance (EPR) results; it was attributedmore » to presence of singly ionized oxygen vacancy centres in ZnAl{sub 2}O{sub 4}. On doping Dy{sup 3+} in ZnAl{sub 2}O{sub 4}, complete host–dopant energy transfer does not take place. Local structural investigation and lifetime measurements reveal that dysprosium ion is distributed between both Zn{sup 2+} and Al{sup 3+} sites. Near white light from ZnAl{sub 2}O{sub 4}:Dy{sup 3+} is attributed to combined host and dopant luminescence. The trap parameters such as activation energy (E) and frequency factor (s) for TSL glow peak 165 °C were determined using different heating rate method. Thermally stimulated emission showed the presence of oxygen related defect centre.« less

Short x-ray pulse generation using deflecting cavities at the Advanced Photon Source.

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

Sajaev, V.; Borland, M.; Chae, Y.-C.

2007-11-11

Storage-ring-based third-generation light sources can provide intense radiation pulses with durations as short as 100 ps. However, there is growing interest within the synchrotron radiation user community in performing experiments with much shorter X-ray pulses. Zholents et al. [Nucl. Instr. and Meth. A 425 (1999) 385] recently proposed using RF orbit deflection to generate sub-ps X-ray pulses. In this scheme, two deflecting cavities are used to deliver a longitudinally dependent vertical kick to the beam. An optical slit can then be used to slice out a short part of the radiation pulse. Implementation of this scheme is planned for onemore » APS beamline in the near future. In this paper, we summarize our feasibility study of this method and the expected X-ray beam parameters. We find that a pulse length of less than two picoseconds can be achieved.« less