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Sample records for heavily absorbed hmxbs

  1. XMM-Newton Observations of the Heavily Absorbed Seyfert 1 Galaxy IC 4329A

    SciTech Connect

    Steenbrugge, K.

    2005-01-05

    We detect seven distinct absorbing systems in the high-resolution X-ray spectrum of the Seyfert 1 galaxy IC 4329A, taken with XMM-Newton. Firstly we detect absorption due to cold gas in our own Galaxy and warm gas in the Galactic halo or the Local Group. This local warm gas is only detected through O VII absorption, from which we deduce a temperature between 0.03 and 0.2 keV. In IC 4329A we detect absorption from the host galaxy as well as from a warm absorber, close to the nucleus, which has 4 components. The absorption from the host galaxy is well modeled by neutral material. The warm absorber detected in IC 4329A is photoionized and has an ionization range between log {xi} = -1.37 and log {xi} = 2.7. A broad excess is measured at the O VIII Ly{alpha} and N VII Ly{alpha} emission lines, which can be modeled by either disklines or multiple Gaussians. From the lightcurve we find that the source changed luminosity by about 20 % over the 140 ks observation, while the spectral shape, i.e. the softness ratio did not vary. In the EPIC spectra a narrow Fe K{alpha} and Fe XXVI Ly{alpha} emission line are detected. The narrowness of the Fe K{alpha} line and the fact that there is no evidence for flux variability between different observations leads us to conclude that the Fe K{alpha} line is formed at a large distance from the central black hole.

  2. Watt-level passively Q-switched heavily Er3+-doped ZBLAN fiber laser with a semiconductor saturable absorber mirror

    PubMed Central

    Shen, Yanlong; Wang, Yishan; Luan, Kunpeng; Huang, Ke; Tao, Mengmeng; Chen, Hongwei; Yi, Aiping; Feng, Guobin; Si, Jinhai

    2016-01-01

    A diode-cladding pumped mid-infrared passively Q-switched Er3+-doped ZBLAN fiber laser with an average output power of watt-level based on a semiconductor saturable absorber mirror (SESAM) is demonstrated. Stable pulse train was produced at a slope efficiency of 17.8% with respect to launched pump power. The maximum average power of 1.01 W at a repetition rate of 146.3 kHz was achieved with a corresponding pulse energy of 6.9 μJ, from which the maximum peak power was calculated to be 21.9 W. To the best of our knowledge, the average power and the peak power are the highest in 3 μm region passively Q-switched fiber lasers. The influence of gain fiber length on the operation regime of the fiber laser has been investigated in detail. PMID:27225029

  3. Watt-level passively Q-switched heavily Er3+-doped ZBLAN fiber laser with a semiconductor saturable absorber mirror

    NASA Astrophysics Data System (ADS)

    Shen, Yanlong; Wang, Yishan; Luan, Kunpeng; Huang, Ke; Tao, Mengmeng; Chen, Hongwei; Yi, Aiping; Feng, Guobin; Si, Jinhai

    2016-05-01

    A diode-cladding pumped mid-infrared passively Q-switched Er3+-doped ZBLAN fiber laser with an average output power of watt-level based on a semiconductor saturable absorber mirror (SESAM) is demonstrated. Stable pulse train was produced at a slope efficiency of 17.8% with respect to launched pump power. The maximum average power of 1.01 W at a repetition rate of 146.3 kHz was achieved with a corresponding pulse energy of 6.9 μJ, from which the maximum peak power was calculated to be 21.9 W. To the best of our knowledge, the average power and the peak power are the highest in 3 μm region passively Q-switched fiber lasers. The influence of gain fiber length on the operation regime of the fiber laser has been investigated in detail.

  4. Watt-level passively Q-switched heavily Er(3+)-doped ZBLAN fiber laser with a semiconductor saturable absorber mirror.

    PubMed

    Shen, Yanlong; Wang, Yishan; Luan, Kunpeng; Huang, Ke; Tao, Mengmeng; Chen, Hongwei; Yi, Aiping; Feng, Guobin; Si, Jinhai

    2016-01-01

    A diode-cladding pumped mid-infrared passively Q-switched Er(3+)-doped ZBLAN fiber laser with an average output power of watt-level based on a semiconductor saturable absorber mirror (SESAM) is demonstrated. Stable pulse train was produced at a slope efficiency of 17.8% with respect to launched pump power. The maximum average power of 1.01 W at a repetition rate of 146.3 kHz was achieved with a corresponding pulse energy of 6.9 μJ, from which the maximum peak power was calculated to be 21.9 W. To the best of our knowledge, the average power and the peak power are the highest in 3 μm region passively Q-switched fiber lasers. The influence of gain fiber length on the operation regime of the fiber laser has been investigated in detail. PMID:27225029

  5. Comparing the spatial distributions of HMXBs and star-forming regions in the Small Magellanic Cloud

    NASA Astrophysics Data System (ADS)

    Bodaghee, Arash; Antoniou, Vallia; Zezas, Andreas; Tomsick, John; Agnew, Ryan; Frechette, Eric; Jackson, Brenton; Jordan, Zachary

    2016-04-01

    Initial results are presented comparing the spatial distribution of high-mass X-ray binaries (HMXBs) and massive stellar nurseries (OB associations) in the Small Magellanic Cloud (SMC). The analysis involves constructing the two-point cross-correlation function between pairs of 72 HMXBs and 234 OB associations with the latter being randomly reshuffled following a homogenous distribution, a Gaussian distribution, and a distribution that mimics the star-formation history of the SMC. We find a significant (>5-sigma) correlation between the observed HMXB and OB catalogs compared with a random catalog in which the OB associations are distributed homogeneously across the SMC field. On average, within a kpc of a given HMXB, there are 4 OB associations from the observed catalog for every one from the randomized catalog. There is no significant difference when comparing the HMXBs with the observed catalog versus the random catalog in which the OB distribution traces the star-formation history. This suggests that HMXBs in the SMC have had less time to migrate away from their birthplaces (or, alternatively, that they have a lower average velocity) than HMXBs in the Milky Way. One explanation is that the HMXBs in our sample all host B-emission-line stars that have not yet left the main sequence.

  6. A comparative study of SG-HMXBS and SFXTS using iron K-alpha line as a tracer

    NASA Astrophysics Data System (ADS)

    Pradhan, Pragati; Paul, Biswajit; Bozzo, Enrico

    2016-07-01

    We present a comparative study of classical supergiant HMXB and SFXT systems by making a detailed study of the variation of the equivalent width of iron k-alpha line with the absorption column density using out-of-eclipse observations from Suzaku, XMM, and Chandra (and taking care not to mix observations in different spectral states). Analysis of the entire archival Suzaku observations of these systems show that the equivalent width of SFXTs is significantly smaller compared to those of classical supergiant HMXBs even when the hydrogen column density of both are comparable. We discuss the results of the analysis in the light of two theories on SFXTS: the clumpy wind and the magnetic gating model. The findings are also used to make a comparison between these two systems as a class.

  7. Sound Absorbers

    NASA Astrophysics Data System (ADS)

    Fuchs, H. V.; Möser, M.

    Sound absorption indicates the transformation of sound energy into heat. It is, for instance, employed to design the acoustics in rooms. The noise emitted by machinery and plants shall be reduced before arriving at a workplace; auditoria such as lecture rooms or concert halls require a certain reverberation time. Such design goals are realised by installing absorbing components at the walls with well-defined absorption characteristics, which are adjusted for corresponding demands. Sound absorbers also play an important role in acoustic capsules, ducts and screens to avoid sound immission from noise intensive environments into the neighbourhood.

  8. Synchronizing Heavily Encoded Data in Bad Weather

    NASA Technical Reports Server (NTRS)

    Swanson, L.

    1985-01-01

    Deep space missions choose a data rate to ensure reliable communication under most conditions. Certain critical data can be more heavily encoded, to be decoded under particularly bad atmospheric conditions. It is shown that, in such a system, finding and synchronizing critical data will not be a problem.

  9. Special tool kit aids heavily garmented workers

    NASA Technical Reports Server (NTRS)

    Holmes, A. E.

    1966-01-01

    Triangular aluminum tool kit, filled with polyurethane is constructed to receive various tools and hold them in a snug but quick-release fit as an aid to heavily gloved workers. The kit is designed to allow mounting within easily accessable reach and to provide protection of the tools during storage.

  10. Imaging optical fields through heavily scattering media.

    PubMed

    Newman, Jason A; Webb, Kevin J

    2014-12-31

    Coherent imaging and communication through or within heavily scattering random media has been considered impossible due to the randomization of the information contained in the scattered electromagnetic field. We report a remarkable result based on speckle correlations over incident field position that demonstrates that the field incident on a heavily scattering random medium can be obtained using a method that is not restricted to weak scatter and is, in principle, independent of the thickness of the scattering medium. Natural motion can be exploited, and the approach can be extended to other geometries. The near-infrared optical results presented indicate that the approach is applicable to other frequency regimes, as well as other wave types. This work presents opportunities to enhance communication channel capacity in the large source and detector number regime, for a new method to view binary stars from Earth, and in biomedical applications. PMID:25615337

  11. Hybrid evolutionary programming for heavily constrained problems.

    PubMed

    Myung, H; Kim, J H

    1996-01-01

    A hybrid of evolutionary programming (EP) and a deterministic optimization procedure is applied to a series of non-linear and quadratic optimization problems. The hybrid scheme is compared with other existing schemes such as EP alone, two-phase (TP) optimization, and EP with a non-stationary penalty function (NS-EP). The results indicate that the hybrid method can outperform the other methods when addressing heavily constrained optimization problems in terms of computational efficiency and solution accuracy. PMID:8833746

  12. Chronology of heavily cratered terrains on Mercury

    NASA Astrophysics Data System (ADS)

    Marchi, S.; Chapman, C. R.

    2012-12-01

    Imaging of Mercury by Mariner 10 revealed a planet with more extensive plains units than on the Moon. Even in heavily cratered terrain, there is a lack of craters <40 km in diameter, relative to the size-frequency distribution on the Moon, a result attributed to resurfacing by the formation of widespread "intercrater plains". MESSENGER imaging has revealed that the more recent smooth plains are generally the result of widespread volcanism (rather than fluidized impact basin ejecta) and that at least localized volcanism may have persisted until comparatively recent times, despite the crustal contraction evidenced by the numerous lobate scarps. The older intercrater plains may also be volcanic. Here we address the ages of the oldest, most heavily cratered regions on Mercury that may predate most of the visible intercrater plains. We scale to Mercury the lunar crater chronology recently developed by Morbidelli et al., [1] in order to interpret new crater counts on these terrains. We find that these craters are probably not saturated but may have been in equilibrium with a rapid resurfacing process, presumably volcanism that formed the earliest recognized intercrater plains. The crater retention age for this terrain, which contains the oldest large craters on Mercury, is surprisingly young, perhaps hundreds of millions of years younger than the heavily cratered pre-Nectarian terrains on the Moon [2]. These results are important for understanding the early geological and geophysical evolution of Mercury. References: [1] Morbidelli A., Marchi S., Bottke W.F., and Kring D.A. 2012. A sawtooth timeline for the first billion years of the lunar bombardment. Earth and Planetary Science Letters, in press. [2] Marchi S., Bottke W.F., Kring D.A., and Morbidelli A. 2012. The onset of the lunar cataclysm as recorded in its ancient crater populations. Earth and Planetary Science Letters 325, 27-38.

  13. Heavily Doped PBSE with High Thermoelectric Performance

    NASA Technical Reports Server (NTRS)

    Snyder, G. Jeffrey (Inventor); Wang, Heng (Inventor); Pei, Yanzhong (Inventor)

    2015-01-01

    The present invention discloses heavily doped PbSe with high thermoelectric performance. Thermoelectric property measurements disclosed herein indicated that PbSe is high zT material for mid-to-high temperature thermoelectric applications. At 850 K a peak zT (is) greater than 1.3 was observed when n(sub H) approximately 1.0 X 10(exp 20) cm(exp -3). The present invention also discloses that a number of strategies used to improve zT of PbTe, such as alloying with other elements, nanostructuring and band modification may also be used to further improve zT in PbSe.

  14. RKKY interaction in heavily vacant graphene.

    PubMed

    Habibi, Alireza; Jafari, S A

    2013-09-18

    Dirac electrons in clean graphene can mediate the interactions between two localized magnetic moments. The functional form of the RKKY interaction in pristine graphene is specified by two main features: (i) an atomic-scale oscillatory part determined by a wavevector Q connecting the two valleys; with doping another longer range oscillation appears which arises from the existence of an extended Fermi surface characterized by a momentum scale kF; (ii) an algebraic R(α) decay in large distances where the exponent α =- 3 is a distinct feature of undoped Dirac sea in two dimensions. In this work, we investigate the effect of a few per cent vacancies on the above properties. Depending on the doping level, if the chemical potential lies on the linear part of the density of states, the exponent α remains at -3 even in vacant graphene. Otherwise α reduces towards more negative values. Presence of vacancies washes out both atomic-scale and Friedel oscillations of the RKKY interaction. The absence of atomic-scale oscillations indicates the destruction of two-valley structure of the parent graphene material. However, the absence of Friedel oscillations upon 'alloying' with vacancies indicates that a quantum ground state of heavily vacant doped graphene is not given by a unique kF momentum scale. PMID:23962815

  15. 4. EAST VIEW OF HEAVILY DETERIORATED SECTION OF SEA WALL ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    4. EAST VIEW OF HEAVILY DETERIORATED SECTION OF SEA WALL LOOKING ACROSS ERODED EASTERN CORNER OF PEA PATCH ISLAND. BUILDING FOUNDATION REMAINS IN FOREGROUND. - Fort Delaware, Sea Wall, Pea Patch Island, Delaware City, New Castle County, DE

  16. Composition for absorbing hydrogen

    DOEpatents

    Heung, L.K.; Wicks, G.G.; Enz, G.L.

    1995-05-02

    A hydrogen absorbing composition is described. The composition comprises a porous glass matrix, made by a sol-gel process, having a hydrogen-absorbing material dispersed throughout the matrix. A sol, made from tetraethyl orthosilicate, is mixed with a hydrogen-absorbing material and solidified to form a porous glass matrix with the hydrogen-absorbing material dispersed uniformly throughout the matrix. The glass matrix has pores large enough to allow gases having hydrogen to pass through the matrix, yet small enough to hold the particles dispersed within the matrix so that the hydrogen-absorbing particles are not released during repeated hydrogen absorption/desorption cycles.

  17. Composition for absorbing hydrogen

    DOEpatents

    Heung, Leung K.; Wicks, George G.; Enz, Glenn L.

    1995-01-01

    A hydrogen absorbing composition. The composition comprises a porous glass matrix, made by a sol-gel process, having a hydrogen-absorbing material dispersed throughout the matrix. A sol, made from tetraethyl orthosilicate, is mixed with a hydrogen-absorbing material and solidified to form a porous glass matrix with the hydrogen-absorbing material dispersed uniformly throughout the matrix. The glass matrix has pores large enough to allow gases having hydrogen to pass through the matrix, yet small enough to hold the particles dispersed within the matrix so that the hydrogen-absorbing particles are not released during repeated hydrogen absorption/desorption cycles.

  18. Modelling Absorbent Phenomena of Absorbent Structure

    NASA Astrophysics Data System (ADS)

    Sayeb, S.; Ladhari, N.; Ben Hassen, M.; Sakli, F.

    Absorption, retention and strike through time, as evaluating criteria of absorbent structures quality were studied. Determination of influent parameters on these criteria were realized by using the design method of experimental sets. In this study, the studied parameters are: Super absorbent polymer (SAP)/fluff ratio, compression and the porosity of the non woven used as a cover stock. Absorption capacity and retention are mostly influenced by SAP/fluff ratio. However, strike through time is affected by compression. Thus, a modelling of these characteristics in function of the important parameter was established.

  19. Methods for absorbing neutrons

    DOEpatents

    Guillen, Donna P.; Longhurst, Glen R.; Porter, Douglas L.; Parry, James R.

    2012-07-24

    A conduction cooled neutron absorber may include a metal matrix composite that comprises a metal having a thermal neutron cross-section of at least about 50 barns and a metal having a thermal conductivity of at least about 1 W/cmK. Apparatus for providing a neutron flux having a high fast-to-thermal neutron ratio may include a source of neutrons that produces fast neutrons and thermal neutrons. A neutron absorber positioned adjacent the neutron source absorbs at least some of the thermal neutrons so that a region adjacent the neutron absorber has a fast-to-thermal neutron ratio of at least about 15. A coolant in thermal contact with the neutron absorber removes heat from the neutron absorber.

  20. Externally tuned vibration absorber

    DOEpatents

    Vincent, Ronald J.

    1987-09-22

    A vibration absorber unit or units are mounted on the exterior housing of a hydraulic drive system of the type that is powered from a pressure wave generated, e.g., by a Stirling engine. The hydraulic drive system employs a piston which is hydraulically driven to oscillate in a direction perpendicular to the axis of the hydraulic drive system. The vibration absorbers each include a spring or other resilient member having one side affixed to the housing and another side to which an absorber mass is affixed. In a preferred embodiment, a pair of vibration absorbers is employed, each absorber being formed of a pair of leaf spring assemblies, between which the absorber mass is suspended.

  1. Advanced neutron absorber materials

    DOEpatents

    Branagan, Daniel J.; Smolik, Galen R.

    2000-01-01

    A neutron absorbing material and method utilizing rare earth elements such as gadolinium, europium and samarium to form metallic glasses and/or noble base nano/microcrystalline materials, the neutron absorbing material having a combination of superior neutron capture cross sections coupled with enhanced resistance to corrosion, oxidation and leaching.

  2. Multispectral metamaterial absorber.

    PubMed

    Grant, J; McCrindle, I J H; Li, C; Cumming, D R S

    2014-03-01

    We present the simulation, implementation, and measurement of a multispectral metamaterial absorber (MSMMA) and show that we can realize a simple absorber structure that operates in the mid-IR and terahertz (THz) bands. By embedding an IR metamaterial absorber layer into a standard THz metamaterial absorber stack, a narrowband resonance is induced at a wavelength of 4.3 μm. This resonance is in addition to the THz metamaterial absorption resonance at 109 μm (2.75 THz). We demonstrate the inherent scalability and versatility of our MSMMA by describing a second device whereby the MM-induced IR absorption peak frequency is tuned by varying the IR absorber geometry. Such a MSMMA could be coupled with a suitable sensor and formed into a focal plane array, enabling multispectral imaging. PMID:24690713

  3. On the take-off of heavily loaded airplanes

    NASA Technical Reports Server (NTRS)

    Breguet, Louis

    1928-01-01

    This report examines the take-off conditions of airplanes equipped with tractive propellers, and particularly the more difficult take-off of airplanes heavily loaded per unit of wing area (wing loading) or per unit of engine power (power loading).

  4. Terahertz emission from silicon nanostructures heavily doped with boron

    NASA Astrophysics Data System (ADS)

    Bagraev, Nikolay T.; Danilovskii, Eduard Yu; Gets, Dmitrii S.; Kaveev, Andrey K.; Klyachkin, Leonid E.; Kropotov, Grigorii I.; Kudryavtsev, Andrey A.; Kuzmin, Roman V.; Malyarenko, Anna M.; Mashkov, Vladimir A.; Tsibizov, Ivan A.; Tsypishka, Dmitrii I.; Vinerov, Ilya A.

    2014-03-01

    We present the first findings of the terahertz emission from the ultra-narrow p-type silicon quantum well confined by the δ-barriers heavily doped with boron on the n-type Si (100) surface. The THz spectra revealed by the voltage applied along the Si-QW plane appear to result from the radiation of the dipole boron centers.

  5. 18. A VIEW EAST, SHOWING THE HEAVILY WOODED BANKS OF ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    18. A VIEW EAST, SHOWING THE HEAVILY WOODED BANKS OF THE ST. JOSEPH RIVER. THIS IS TYPICAL OF THE RIVERSIDE ENVIRONMENT OF THE BRIDGE. - County Line Bridge, Spanning St. Joseph River at State Route 219, 0.6 mile south of U.S. Route 20, Osceola, St. Joseph County, IN

  6. Internal absorber solar collector

    DOEpatents

    Sletten, Carlyle J.; Herskovitz, Sheldon B.; Holt, F. S.; Sletten, E. J.

    1981-01-01

    Thin solar collecting panels are described made from arrays of small rod collectors consisting of a refracting dielectric rod lens with an absorber imbedded within it and a reflecting mirror coated on the back side of the dielectric rod. Non-tracking collector panels on vertical walls or roof tops receive approximately 90% of solar radiation within an acceptance zone 60.degree. in elevation angle by 120.degree. or more in the azimuth sectors with a collector concentration ratio of approximately 3.0. Miniaturized construction of the circular dielectric rods with internal absorbers reduces the weight per area of glass, plastic and metal used in the collector panels. No external parts or insulation are needed as heat losses are low due to partial vacuum or low conductivity gas surrounding heated portions of the collector. The miniature internal absorbers are generally made of solid copper with black selective surface and the collected solar heat is extracted at the collector ends by thermal conductivity along the absorber rods. Heat is removed from end fittings by use of liquid circulants. Several alternate constructions are provided for simplifying collector panel fabrication and for preventing the thermal expansion and contraction of the heated absorber or circulant tubes from damaging vacuum seals. In a modified version of the internal absorber collector, oil with temperature dependent viscosity is pumped through a segmented absorber which is now composed of closely spaced insulated metal tubes. In this way the circulant is automatically diverted through heated portions of the absorber giving higher collector concentration ratios than theoretically possible for an unsegmented absorber.

  7. Metal shearing energy absorber

    NASA Technical Reports Server (NTRS)

    Fay, R. J.; Wittrock, E. P. (Inventor)

    1973-01-01

    A metal shearing energy absorber is described. The absorber is composed of a flat thin strip of metal which is pulled through a slot in a cutter member of a metal, harder than the metal of the strip. The slot's length, in the direction perpendicular to the pull direction, is less than the strip's width so that as the strip is pulled through the slot, its edges are sheared off, thereby absorbing some of the pulling energy. In one embodiment the cutter member is a flat plate of steel, while in another embodiment the cutter member is U-shaped with the slot at its base.

  8. Lipid-absorbing Polymers

    NASA Technical Reports Server (NTRS)

    Marsh, H. E., Jr.; Wallace, C. J.

    1973-01-01

    The removal of bile acids and cholesterol by polymeric absorption is discussed in terms of micelle-polymer interaction. The results obtained with a polymer composed of 75 parts PEO and 25 parts PB plus curing ingredients show an absorption of 305 to 309%, based on original polymer weight. Particle size effects on absorption rate are analyzed. It is concluded that crosslinked polyethylene oxide polymers will absorb water, crosslinked polybutadiene polymers will absorb lipids; neither polymer will absorb appreciable amounts of lipids from micellar solutions of lipids in water.

  9. "Smart" Electromechanical Shock Absorber

    NASA Technical Reports Server (NTRS)

    Stokes, Lebarian; Glenn, Dean C.; Carroll, Monty B.

    1989-01-01

    Shock-absorbing apparatus includes electromechanical actuator and digital feedback control circuitry rather than springs and hydraulic damping as in conventional shock absorbers. Device not subject to leakage and requires little or no maintenance. Attenuator parameters adjusted in response to sensory feedback and predictive algorithms to obtain desired damping characteristic. Device programmed to decelerate slowly approaching vehicle or other large object according to prescribed damping characteristic.

  10. Iron Chalcogenide Photovoltaic Absorbers

    SciTech Connect

    Yu, Liping; Lany, Stephan; Kykyneshi, Robert; Jieratum, Vorranutch; Ravichandran, Ram; Pelatt, Brian; Altschul, Emmeline; Platt, Heather A. S.; Wager, John F.; Keszler, Douglas A.; Zunger, Alex

    2011-08-10

    An integrated computational and experimental study of FeS₂ pyrite reveals that phase coexistence is an important factor limiting performance as a thin-film solar absorber. This phase coexistence is suppressed with the ternary materials Fe₂SiS₄ and Fe₂GeS₄, which also exhibit higher band gaps than FeS₂. Thus, the ternaries provide a new entry point for development of thin-film absorbers and high-efficiency photovoltaics.

  11. A reactive flow model for heavily aluminized cyclotrimethylene-trinitramine

    SciTech Connect

    Kim, Bohoon; Lee, Kyung-Cheol; Yoh, Jack J.; Park, Jungsu

    2014-07-14

    An accurate and reliable prediction of reactive flow is a challenging task when characterizing an energetic material subjected to an external shock impact as the detonation transition time is on the order of a micro second. The present study aims at investigating the size effect behavior of a heavily aluminized cyclotrimethylene-trinitramine (RDX) which contains 35% of aluminum by using a detonation rate model that includes ignition and growth mechanisms for shock initiation and subsequent detonation. A series of unconfined rate stick tests and two-dimensional hydrodynamic simulations are conducted to construct the size effect curve which represents the relationship between detonation velocity and inverse radius of the charge. A pressure chamber test is conducted to further validate the reactive flow model for predicting the response of a heavily aluminized high explosive subjected to an external impact.

  12. Transit time and charge storage measurements in heavily doped emitters

    NASA Technical Reports Server (NTRS)

    Neugroschel, A.; Park, J. S.; Hwang, B. Y.

    1986-01-01

    A first direct measurement of the minority-carrier transit time in a transparent heavily doped emitter layer is reported. The value was obtained by a high-frequency conductance method recently developed and used for low-doped Si. The transit time coupled with the steady-state current enables the determination of the quasi-static charge stored in the emitter and the quasi-static emitter capacitance. Using a transport model, from the measured transit time, the value for the minority-carrier diffusion coefficient and mobility is estimated. The measurements were done using a heavily doped emitter of the Si p(+)-n-p bipolar transistor. The new result indicates that the position-averaged minority-carrier diffusion coefficients may be much smaller than the corresponding majority-carrier values for emitters having a concentration ranging from about 3 x 10 to the 19th per cu cm to 10 to the 20th per cu cm.

  13. Optical properties of laser-induced heavily doped Si

    NASA Astrophysics Data System (ADS)

    Ravindra, N. M.; Mhoronge, J. F.; Jouanne, M.

    1985-09-01

    An analysis of experimental studies (Slaoui et al., 1983) of the optical properties of laser-induced heavily doped Si layers is presented. The analysis has been made on the basis of models like those of Penn (1962) and Breckenridge et al. (1974). The calculations show that, in general, the effective number of electrons contributing to optically induced electronic transitions, increases as does the imaginary part of the complex dielectric constant. This reflects an increased absorption coefficient for these As-doped samples. These studies have been carried out on samples of Si heavily doped by ion-implantation followed by a laser-annealing process. The conclusions based on these studies are seen to be in accord with those of Aspnes et al. (1984) and Vina and Cardona (1984).

  14. Unidirectional perfect absorber.

    PubMed

    Jin, L; Wang, P; Song, Z

    2016-01-01

    This study proposes a unidirectional perfect absorber (UPA), which we realized with a two-arm Aharonov-Bohm interferometer, that consists of a dissipative resonator side-coupled to a uniform resonator array. The UPA has reflection-less full absorption on one direction, and reflectionless full transmission on the other, with an appropriate magnetic flux and coupling, detuning, and loss of the side-coupled resonator. The magnetic flux controls the transmission, the left transmission is larger for magnetic flux less than one-half flux quantum; and the right transmission is larger for magnetic flux between one-half and one flux quantum. Besides, a perfect absorber (PA) can be realized based on the UPA, in which light waves from both sides, with arbitrary superposition of the ampli- tude and phase, are perfectly absorbed. The UPA is expected to be useful in the design of novel optical devices. PMID:27615125

  15. Nondestructive depth-resolved spectroscopic investigation of the heavily intermixed In2S3/Cu(In,Ga)Se2 interface

    SciTech Connect

    Bar, Marcus; Barreau, N.; Couzinie-Devy, F.; Pookpanratana, S.; Klaer, J.; Blum, M.; Zhang, Y.; Yang, W.; Denlinger, J.D.; Schock, H.W.; Weinhardt, L.; Kessler, J.; Heske, Clemens

    2010-04-06

    The chemical structure of the interface between a nominal In2S3 buffer and a Cu(In,Ga)Se2 (CIGSe) thin-film solar cell absorber was investigated by soft x-ray photoelectron and emission spectroscopy. We find a heavily intermixed, complex interface structure, in which Cu diffuses into (and Na through) the buffer layer, while the CIGSe absorber surface/interface region is partially sulfurized. Based on our spectroscopic analysis, a comprehensive picture of the chemical interface structure is proposed.

  16. Multiple-layer Radiation Absorber

    NASA Astrophysics Data System (ADS)

    Baker, Robert M. L.; Baker, Bonnie Sue

    A structure is discussed for absorbing incident radiation, either electromagnetic (EM) or sound. Such a surface structure is needed, for example, in a highly sensitive high-frequency gravitational wave or HFGW detector such as the Li-Baker. The multi-layer absorber, which is discussed, is constructed with metamaterial [MM] layer or layers on top. This MM is configured for a specific EM or sound radiation frequency band, which absorbs incident EM or sound radiation without reflection. Below these top MM layers is a substrate of conventional EM-radiation absorbing or acoustical absorbing reflective material, such as an array of pyramidal foam absorbers. Incident radiation is partially absorbed by the MM layer or layers, and then it is more absorbed by the lower absorbing and reflecting substrate. The remaining reflected radiation is even further absorbed by the MM layers on its "way out_ so that essentially all of the incident radiation is absorbed _ a nearly perfect black-body absorber. In a HFGW detector a substrate, such as foam absorbers, may outgas into a high vacuum and reduce the capability of the vacuum-producing equipment, however, the layers above this lowest substrate will seal the absorbing and reflecting substrate from any external vacuum. The layers also serve to seal the absorbing material against air or water flow past the surfaces of aircraft, watercraft or submarines. Other applications for such a multiple-level radiation absorber include stealth aircraft, missiles and submarines.

  17. Multiple phosphorus chemical sites in heavily phosphorus-doped diamond

    SciTech Connect

    Okazaki, Hiroyuki; Yoshida, Rikiya; Muro, Takayuki; Nakamura, Tetsuya; Hirai, Masaaki; Kato, Hiromitsu; Yamasaki, Satoshi; Takano, Yoshihiko; Ishii, Satoshi; Oguchi, Tamio

    2011-02-21

    We have performed high-resolution core level photoemission spectroscopy on a heavily phosphorus (P)-doped diamond film in order to elucidate the chemical sites of doped-phosphorus atoms in diamond. P 2p core level study shows two bulk components, providing spectroscopic evidence for multiple chemical sites of doped-phosphorus atoms. This indicates that only a part of doped-phosphorus atoms contribute to the formation of carriers. From a comparison with band calculations, possible origins for the chemical sites are discussed.

  18. Measurement of surface recombination velocity on heavily doped indium phosphide

    NASA Technical Reports Server (NTRS)

    Jenkins, Phillip; Ghalla-Goradia, Manju; Faur, Mircea; Faur, Maria; Bailey, Sheila

    1990-01-01

    Surface recombination velocity (SRV) on heavily doped n-type and p-type InP was measured as a function of surface treatment. For the limited range of substrates and surface treatments studied, SRV and surface stability depend strongly on the surface treatment. SRVs of 100,000 cm/sec in both p-type and n-type InP are obtainable, but in n-type the low-SRV surfaces were unstable, and the only stable surfaces on n-type had SRVs of more than 10to the 6th cm/sec.

  19. Carrier scattering by native defects in heavily doped semiconductors

    SciTech Connect

    Walukiewicz, W. Materials and Chemical Sciences Division, Lawrence Berkeley Laboratory, 1 Cyclotron Road, Berkeley, CA )

    1990-05-15

    Calculations of the effect of charged native defects on carrier mobility in semiconductors are presented. The concentrations of native defects are calculated within the framework of the recently proposed amphoteric-native-defect model. The model provides a simple rule for identification of semiconductor systems in which defect scattering is important. It is shown that native-defect scattering is a dominant mechanism limiting electron mobilities in heavily doped {ital n}-type GaAs. It is also shown that native defects do not play any significant role in {ital p}-type GaAs.

  20. Neutron Absorbing Alloys

    DOEpatents

    Mizia, Ronald E.; Shaber, Eric L.; DuPont, John N.; Robino, Charles V.; Williams, David B.

    2004-05-04

    The present invention is drawn to new classes of advanced neutron absorbing structural materials for use in spent nuclear fuel applications requiring structural strength, weldability, and long term corrosion resistance. Particularly, an austenitic stainless steel alloy containing gadolinium and less than 5% of a ferrite content is disclosed. Additionally, a nickel-based alloy containing gadolinium and greater than 50% nickel is also disclosed.

  1. Improved thermoelectric properties in heavily doped FeGa3

    NASA Astrophysics Data System (ADS)

    Ponnambalam, V.; Morelli, Donald T.

    2015-12-01

    FeGa3, a hybridization gap semiconductor, has been substituted with an n-type dopant Ge to form a series of compositions FeGa3-xGex. Electrical and thermal transport properties of these compositions have been studied. Change in carrier density (n) is evident from the Hall measurements. The carrier density (n) can be as high as ˜1021 cm-3 in these compositions. In order to study the role of heavy doping on the thermoelectric properties of FeGa3, an alloy series Fe1-yCoyGa3-xGex has also been synthesized with higher concentrations of Ge (x = 0.1-0.35) and Co (y = 0.1-0.5). From resistivity and Seebeck coefficient measurements, it appears that heavy doping is accomplished by the simultaneous substitutions of Ge and Co. The systematic change in both resistivity (ρ) and Seebeck coefficient (α) is possibly due to change in the carrier density (n). The power factor (PF) α2/ρ improves steadily with increasing carrier density and the best PF ˜1.1 mW/m K2 is observed for the heavily doped compositions at 875 K. In the alloy series Fe1-yCoyGa3-xGex, thermal conductivity is also reduced substantially due to point defect scattering. Due to higher power factors, the figure of merit ZT improves to 0.25 at 875 K for the heavily doped compositions.

  2. Electrochemical Decontamination of Painted and Heavily Corroded Metals

    SciTech Connect

    Marczak, S.; Anderson, J.; Dziewinski, J.

    1998-09-08

    The radioactive metal wastes that are generated from nuclear fuel plants and radiochemical laboratories are mainly contaminated by the surface deposition of radioactive isotopes. There are presently several techniques used in removing surface contamination involving physical and chemical processes. However, there has been very little research done in the area of soiled, heavily oxidized, and painted metals. Researchers at Los Alamos National Laboratory have been developing electrochemical procedures for the decontamination of bare and painted metal objects. These methods have been found to be effective on highly corroded as well as relatively new metals. This study has been successful in decontaminating projectiles and shrapnel excavated during environmental restoration projects after 40+ years of exposure to the elements. Heavily corroded augers used in sampling activities throughout the area were also successfully decontaminated. This process has demonstrated its effectiveness and offers several advantages over the present metal decontamination practices of media blasting and chemical solvents. These advantages include the addition of no toxic or hazardous chemicals, low operating temperature and pressure, and easily scaleable equipment. It is in their future plans to use this process in the decontamination of gloveboxes destined for disposal as TRU waste.

  3. Near-infrared free carrier absorption in heavily doped silicon

    SciTech Connect

    Baker-Finch, Simeon C.; McIntosh, Keith R.; Yan, Di; Fong, Kean Chern; Kho, Teng C.

    2014-08-14

    Free carrier absorption in heavily doped silicon can have a significant impact on devices operating in the infrared. In the near infrared, the free carrier absorption process can compete with band to band absorption processes, thereby reducing the number of available photons to optoelectronic devices such as solar cells. In this work, we fabricate 18 heavily doped regions by phosphorus and boron diffusion into planar polished silicon wafers; the simple sample structure facilitates accurate and precise measurement of the free carrier absorptance. We measure and model reflectance and transmittance dispersion to arrive at a parameterisation for the free carrier absorption coefficient that applies in the wavelength range between 1000 and 1500 nm, and the range of dopant densities between ∼10{sup 18} and 3 × 10{sup 20} cm{sup −3}. Our measurements indicate that previously published parameterisations underestimate the free carrier absorptance in phosphorus diffusions. On the other hand, published parameterisations are generally consistent with our measurements and model for boron diffusions. Our new model is the first to be assigned uncertainty and is well-suited to routine device analysis.

  4. Metasurface Broadband Solar Absorber

    DOE PAGESBeta

    Azad, Abul K.; Kort-Kamp, Wilton J. M.; Sykora, Milan; Weisse-Bernstein, Nina R.; Luk, Ting S.; Taylor, Antoinette J.; Dalvit, Diego A. R.; Chen, Hou-Tong

    2016-02-01

    Here, we demonstrate a broadband, polarization independent, wide-angle absorber based on a metallic metasurface architecture, which accomplishes greater than 90% absorptance in the visible and near-infrared range of the solar spectrum, and exhibits low absorptivity (emissivity) at mid- and far-infrared wavelengths. The complex unit cell of the metasurface solar absorber consists of eight pairs of gold nano-resonators that are separated from a gold ground plane by a thin silicon dioxide spacer. Moreover, our experimental measurements reveal high-performance absorption over a wide range of incidence angles for both s- and p-polarizations. We also investigate numerically the frequency-dependent field and current distributionsmore » to elucidate how the absorption occurs within the metasurface structure.« less

  5. Metasurface Broadband Solar Absorber

    PubMed Central

    Azad, Abul K.; Kort-Kamp, Wilton J. M.; Sykora, Milan; Weisse-Bernstein, Nina R.; Luk, Ting S.; Taylor, Antoinette J.; Dalvit, Diego A. R.; Chen, Hou-Tong

    2016-01-01

    We demonstrate a broadband, polarization independent, wide-angle absorber based on a metallic metasurface architecture, which accomplishes greater than 90% absorptance in the visible and near-infrared range of the solar spectrum, and exhibits low absorptivity (emissivity) at mid- and far-infrared wavelengths. The complex unit cell of the metasurface solar absorber consists of eight pairs of gold nano-resonators that are separated from a gold ground plane by a thin silicon dioxide spacer. Our experimental measurements reveal high-performance absorption over a wide range of incidence angles for both s- and p-polarizations. We also investigate numerically the frequency-dependent field and current distributions to elucidate how the absorption occurs within the metasurface structure. PMID:26828999

  6. Metasurface Broadband Solar Absorber

    NASA Astrophysics Data System (ADS)

    Azad, Abul K.; Kort-Kamp, Wilton J. M.; Sykora, Milan; Weisse-Bernstein, Nina R.; Luk, Ting S.; Taylor, Antoinette J.; Dalvit, Diego A. R.; Chen, Hou-Tong

    2016-02-01

    We demonstrate a broadband, polarization independent, wide-angle absorber based on a metallic metasurface architecture, which accomplishes greater than 90% absorptance in the visible and near-infrared range of the solar spectrum, and exhibits low absorptivity (emissivity) at mid- and far-infrared wavelengths. The complex unit cell of the metasurface solar absorber consists of eight pairs of gold nano-resonators that are separated from a gold ground plane by a thin silicon dioxide spacer. Our experimental measurements reveal high-performance absorption over a wide range of incidence angles for both s- and p-polarizations. We also investigate numerically the frequency-dependent field and current distributions to elucidate how the absorption occurs within the metasurface structure.

  7. Metasurface Broadband Solar Absorber.

    PubMed

    Azad, Abul K; Kort-Kamp, Wilton J M; Sykora, Milan; Weisse-Bernstein, Nina R; Luk, Ting S; Taylor, Antoinette J; Dalvit, Diego A R; Chen, Hou-Tong

    2016-01-01

    We demonstrate a broadband, polarization independent, wide-angle absorber based on a metallic metasurface architecture, which accomplishes greater than 90% absorptance in the visible and near-infrared range of the solar spectrum, and exhibits low absorptivity (emissivity) at mid- and far-infrared wavelengths. The complex unit cell of the metasurface solar absorber consists of eight pairs of gold nano-resonators that are separated from a gold ground plane by a thin silicon dioxide spacer. Our experimental measurements reveal high-performance absorption over a wide range of incidence angles for both s- and p-polarizations. We also investigate numerically the frequency-dependent field and current distributions to elucidate how the absorption occurs within the metasurface structure. PMID:26828999

  8. Ionized Absorbers in AGN

    NASA Astrophysics Data System (ADS)

    Mathur, S.

    1999-08-01

    As a part of this program, we observed three AGN:PKS2251 + 113, PG0043 = 039 and PLH909. Two objects show signatures of absorbtion in their UV spectra. Based on our earlier modeling of X-ray warm absorbents, we expected to observe X-ray observation in these objects. The third, PLH909, is known to have soft excess in EINSTEIN data. Attachment: "Exploratory ASCA observation of broad absorption line quasi-stellar objects".

  9. Ionized Absorbers in AGN

    NASA Technical Reports Server (NTRS)

    Mathur, S.

    1999-01-01

    As a part of this program, we observed three AGN:PKS2251 + 113, PG0043 = 039 and PLH909. Two objects show signatures of absorbtion in their UV spectra. Based on our earlier modeling of X-ray warm absorbents, we expected to observe X-ray observation in these objects. The third, PLH909, is known to have soft excess in EINSTEIN data. Attachment: "Exploratory ASCA observation of broad absorption line quasi-stellar objects".

  10. Secondary binding sites for heavily modified triplex forming oligonucleotides

    PubMed Central

    Cardew, Antonia S.; Brown, Tom; Fox, Keith R.

    2012-01-01

    In order to enhance DNA triple helix stability synthetic oligonucleotides have been developed that bear amino groups on the sugar or base. One of the most effective of these is bis-amino-U (B), which possesses 5-propargylamino and 2′-aminoethoxy modifications. Inclusion of this modified nucleotide not only greatly enhances triplex stability, but also increases the affinity for related sequences. We have used a restriction enzyme protection, selection and amplification assay (REPSA) to isolate sequences that are bound by the heavily modified 9-mer triplex-forming oligonucleotide B6CBT. The isolated sequences contain An tracts (n = 6), suggesting that the 5′-end of this TFO was responsible for successful triplex formation. DNase I footprinting with these sequences confirmed triple helix formation at these secondary targets and demonstrated no interaction with similar oligonucleotides containing T or 5-propargylamino-dU. PMID:22180535

  11. Thermoelectric properties of heavily boron- and phosphorus-doped silicon

    NASA Astrophysics Data System (ADS)

    Ohishi, Yuji; Xie, Jun; Miyazaki, Yoshinobu; Aikebaier, Yusufu; Muta, Hiroaki; Kurosaki, Ken; Yamanaka, Shinsuke; Uchida, Noriyuki; Tada, Tetsuya

    2015-07-01

    In recent years, nanostructured thermoelectric materials have attracted much attention. However, despite this increasing attention, available information on the thermoelectric properties of single-crystal Si is quite limited, especially for high doping concentrations at high temperatures. In this study, the thermoelectric properties of heavily doped (1018-1020 cm-3) n- and p-type single-crystal Si were studied from room temperature to above 1000 K. The figures of merit, ZT, were calculated from the measured data of electrical conductivity, Seebeck coefficient, and thermal conductivity. The maximum ZT values were 0.015 for n-type and 0.008 for p-type Si at room temperature. To better understand the carrier and phonon transport and to predict the thermoelectric properties of Si, we have developed a simple theoretical model based on the Boltzmann transport equation with the relaxation-time approximation.

  12. Microbial removal of toxic metals from a heavily polluted soil

    NASA Astrophysics Data System (ADS)

    Nicolova, Marina; Spasova, Irena; Georgiev, Plamen; Groudev, Stoyan

    2015-04-01

    Samples of a leached cinnamonic forest soil heavily polluted with uranium and some toxic heavy metals (mainly copper, zinc and cadmium) were subjected to cleaning by means of bioleaching with acidophilic chemolithotrophic bacteria. The treatment was carried out in a green house in which several plots containing 150 kg of soil each were constructed. The effect of some essential environmental factors such as pH, humidity, temperature and contents of nutrients on the cleaning process was studied. It was found that under optimal conditions the content of pollutants were decreased below the relevant permissible levels within a period of 170 days. The soil cleaned in this way was characterized by a much higher production of biomass of different plants (alfalfa, clover, red fescue, vetch) than the untreated polluted soil.

  13. Tidal changes in a heavily modified coastal wetland

    NASA Astrophysics Data System (ADS)

    Ferrarin, Christian; Tomasin, Alberto; Bajo, Marco; Petrizzo, Antonio; Umgiesser, Georg

    2015-06-01

    Changes in tidal regime in the heavily modified Venice Lagoon, Italy, are investigated using long-term observations and numerical modelling. The amplitudes of the major tidal constituents exhibit a significant increase over the last century. Analysis of tide gauge data in the adjacent Adriatic Sea reveals that these changes could be only partially attributed to the rise of the mean sea level. Numerical experiments confirm that natural and anthropogenic morphological changes are responsible for the alteration of tidal regime inside the lagoon. Temporal and spatial changes in tidal asymmetry highlight the complex impacts of human interventions on tidal changes and long-term morphodynamics. Our results suggest that over time the lagoon became more and more an ebb-dominant system. Moreover, in Venice the tidal modulations are significantly impacting the frequency with which high water level thresholds are exceeded. Occurrence of flooding events is therefore influenced by sea level rise and secondarily by the increase in amplitude of principal tidal waves.

  14. Absorber for terahertz radiation management

    DOEpatents

    Biallas, George Herman; Apeldoorn, Cornelis; Williams, Gwyn P.; Benson, Stephen V.; Shinn, Michelle D.; Heckman, John D.

    2015-12-08

    A method and apparatus for minimizing the degradation of power in a free electron laser (FEL) generating terahertz (THz) radiation. The method includes inserting an absorber ring in the FEL beam path for absorbing any irregular THz radiation and thus minimizes the degradation of downstream optics and the resulting degradation of the FEL output power. The absorber ring includes an upstream side, a downstream side, and a plurality of wedges spaced radially around the absorber ring. The wedges form a scallop-like feature on the innermost edges of the absorber ring that acts as an apodizer, stopping diffractive focusing of the THz radiation that is not intercepted by the absorber. Spacing between the scallop-like features and the shape of the features approximates the Bartlett apodization function. The absorber ring provides a smooth intensity distribution, rather than one that is peaked on-center, thereby eliminating minor distortion downstream of the absorber.

  15. Corrosion resistant neutron absorbing coatings

    SciTech Connect

    Choi, Jor-Shan; Farmer, Joseph C.; Lee, Chuck K.; Walker, Jeffrey; Russell, Paige; Kirkwood, Jon; Yang, Nancy; Champagne, Victor

    2012-05-29

    A method of forming a corrosion resistant neutron absorbing coating comprising the steps of spray or deposition or sputtering or welding processing to form a composite material made of a spray or deposition or sputtering or welding material, and a neutron absorbing material. Also a corrosion resistant neutron absorbing coating comprising a composite material made of a spray or deposition or sputtering or welding material, and a neutron absorbing material.

  16. Corrosion resistant neutron absorbing coatings

    SciTech Connect

    Choi, Jor-Shan; Farmer, Joseph C; Lee, Chuck K; Walker, Jeffrey; Russell, Paige; Kirkwood, Jon; Yang, Nancy; Champagne, Victor

    2013-11-12

    A method of forming a corrosion resistant neutron absorbing coating comprising the steps of spray or deposition or sputtering or welding processing to form a composite material made of a spray or deposition or sputtering or welding material, and a neutron absorbing material. Also a corrosion resistant neutron absorbing coating comprising a composite material made of a spray or deposition or sputtering or welding material, and a neutron absorbing material.

  17. Solar radiation absorbing material

    DOEpatents

    Googin, John M.; Schmitt, Charles R.; Schreyer, James M.; Whitehead, Harlan D.

    1977-01-01

    Solar energy absorbing means in solar collectors are provided by a solar selective carbon surface. A solar selective carbon surface is a microporous carbon surface having pores within the range of 0.2 to 2 micrometers. Such a surface is provided in a microporous carbon article by controlling the pore size. A thermally conductive substrate is provided with a solar selective surface by adhering an array of carbon particles in a suitable binder to the substrate, a majority of said particles having diameters within the range of about 0.2-10 microns.

  18. Absorber for solar power.

    PubMed

    Powell, W R

    1974-10-01

    A simple, economical absorber utilizing a new principle of operation to achieve very low reradiation losses while generating temperatures limited by material properties of quartz is described. Its performance is analyzed and indicates approximately 90% thermal efficiency and 73% conversion efficiency for an earth based unit with moderately concentrated (~tenfold) sunlight incident. It is consequently compatible with the most economic of concentrator mirrors (stamped) or mirrors deployable in space. Space applications are particularly attractive, as temperatures significantly below 300 K are possible and permit even higher conversion efficiency. PMID:20134700

  19. Liquid Cryogen Absorber for MICE

    SciTech Connect

    Baynham, D.E.; Bish, P.; Bradshaw, T.W.; Cummings, M.A.; Green,M.A.; Ishimoto, S.; Ivaniouchenkov, I.; Lau, W.; Yang, S.Q.; Zisman, M.S.

    2005-08-20

    The Muon Ionization Cooling Experiment (MICE) will test ionization cooling of muons. In order to have effective ionization cooling, one must use an absorber that is made from a low-z material. The most effective low z materials for ionization cooling are hydrogen, helium, lithium hydride, lithium and beryllium, in that order. In order to measure the effect of material on cooling, several absorber materials must be used. This report describes a liquid-hydrogen absorber that is within a pair of superconducting focusing solenoids. The absorber must also be suitable for use with liquid helium. The following absorber components are discussed in this report; the absorber body, its heat exchanger, the hydrogen system, and the hydrogen safety. Absorber cooling and the thin windows are not discussed here.

  20. General theory of intraband relaxation processes in heavily doped graphene

    NASA Astrophysics Data System (ADS)

    Kupčić, I.

    2015-05-01

    The frequency and wave-vector-dependent memory function in the longitudinal conductivity tensor of weakly interacting electronic systems is calculated by using an approach based on quantum transport equations. In this paper, we show that there is a close relation between the single-electron self-energy, the electron-hole pair self-energy, and the memory function. It is also shown in which way singular long-range Coulomb interactions, together with other q ≈0 scattering processes, drop out of both the memory function and the related transport equations. The theory is illustrated on heavily doped graphene, which is the prototype of weakly interacting single-band electron-phonon systems. A steplike increase of the width of the quasiparticle peak in angle-resolved photoemission spectra at frequencies of the order of the frequency of in-plane optical phonons is shown to be consistent with the behavior of an intraband plasmon peak in the energy loss spectroscopy spectra. Both anomalies can be understood as a direct consequence of weak electron scattering from in-plane optical phonons.

  1. Hydrogen structures in heavily hydrogenated crystalline and amorphous silicon

    SciTech Connect

    Jackson, W.G.; Franz, A.; Chabal, Y.; Weldon, M.K.; Jin, H.C.; Abelson, J.R.

    1998-12-31

    The hydrogen binding energy distribution and IR spectra of hydrogen platelets in c-Si have been measured and compared to H in other forms of silicon including hydrogenated polycrystalline and amorphous Si. The binding distribution for platelet containing samples, determined using H evolution, exhibits two peaks: a bulk peak at 1.8--1.9 eV below the transport barrier, and a second possibly surface related peak 1.8--1.9 eV below the surface evolution barrier. The bulk peak grows at 250 C and is consistent with calculated energies for platelet structures. The same two evolution peaks are found in hydrogenated polycrystalline Si and amorphous silicon. The IR spectra for heavily hydrogenated c-Si are dominated by the stretching modes at 2076 and 2128 cm{sup {minus}1}. Most surprisingly there appears to be a strong mode at 856 cm{sup {minus}1} which is associated with a deformation mode of SiH{sub 3}. Even more surprising, this SiH{sub 3} 856 cm{sup {minus}1} mode remains until 550 C indicating that the SiH{sub 3} containing structures are rather stable.

  2. Source and sink of nitrite in heavily populated European River

    NASA Astrophysics Data System (ADS)

    Raimonet, M.; Viollier, E.; Culoma, L.; Laverman, A.

    2012-12-01

    The occurrence of nitrite (NO2-) accumulation is a major environmental issue, as NO2- is highly toxic to living organisms, even at low concentrations. Even if NO2- is generally quickly oxidized in the environment, NO2- accumulation has been reported in various terrestrial and aquatic environments. The Seine River - that receive water effluents from one of the most heavily populated system in Europe - is characterized by NO2- accumulation downstream of Paris city. The main hypotheses to explain the persistence of NO2- are high NO2- concentrations in outlets of the biggest European waste water treatment plant and the low growth rate of nitrifying bacteria - and especially, nitrite oxidizing bacteria - compared to river water residence time. However, the role of benthic processes and sediment resuspension on NO2- dynamics has not been investigated in the river, where fluvial transport generates episodic and frequent resuspension. In this study, we quantified reaction rates of processes involving NO2- production and/or consumption in surface water and sediments, as well as benthic exchanges at the sediment-water interface, under oxic and anoxic conditions. This work allowed estimating the contribution of the Seine River to NO2- dynamics and the response of riverine bacteria to high NO2- loads.

  3. Sorafenib in advanced, heavily pretreated patients with soft tissue sarcomas.

    PubMed

    Brämswig, Kira; Ploner, Ferdinand; Martel, Alexandra; Bauernhofer, Thomas; Hilbe, Wolfgang; Kühr, Thomas; Leitgeb, Clemens; Mlineritsch, Brigitte; Petzer, Andreas; Seebacher, Veronika; Stöger, Herbert; Girschikofsky, Michael; Hochreiner, Gerhard; Ressler, Sigrun; Romeder, Franz; Wöll, Ewald; Brodowicz, Thomas

    2014-08-01

    Therapeutic options for patients with advanced pretreated soft tissue sarcomas are limited. However, in this setting, sorafenib has shown promising results. We reviewed the data of 33 patients with soft tissue sarcoma treated with sorafenib within a named patient program in Austria. Twelve physicians from eight different hospitals provided records for the analysis of data. Among the 33 patients, the predominant histological subtype of sarcoma was leiomyosarcoma (n=18, 55%). Other subtypes were represented by only one or two cases. Fifteen patients presented with metastases at the time of diagnosis. Another 17 patients developed metastases later in the course of the disease (data on one patient are missing). Most of the 33 patients had undergone resection of the primary (n=29, 88%) and half of the patients had received radiotherapy (n=17, 52%). Chemotherapy for metastatic disease had been administered to 30 patients (91%). The majority had received two or more regimens of chemotherapy (n=25, 76%) before sorafenib treatment. The use of sorafenib resulted in a median time to treatment failure of 92 days in patients with leiomyosarcoma and 45 days in patients with other histological subtypes. One-third of the patients derived benefits from treatment: four patients were documented with partial response and six with stabilized disease. In terms of treatment-related toxicity, skin problems of various degrees and gastrointestinal disturbances were frequently reported. In this retrospective analysis of heavily pretreated patients with advanced soft tissue sarcomas, sorafenib was associated with some antitumor activity and an acceptable toxicity profile. PMID:24667659

  4. Metamaterial electromagnetic wave absorbers.

    PubMed

    Watts, Claire M; Liu, Xianliang; Padilla, Willie J

    2012-06-19

    The advent of negative index materials has spawned extensive research into metamaterials over the past decade. Metamaterials are attractive not only for their exotic electromagnetic properties, but also their promise for applications. A particular branch-the metamaterial perfect absorber (MPA)-has garnered interest due to the fact that it can achieve unity absorptivity of electromagnetic waves. Since its first experimental demonstration in 2008, the MPA has progressed significantly with designs shown across the electromagnetic spectrum, from microwave to optical. In this Progress Report we give an overview of the field and discuss a selection of examples and related applications. The ability of the MPA to exhibit extreme performance flexibility will be discussed and the theory underlying their operation and limitations will be established. Insight is given into what we can expect from this rapidly expanding field and future challenges will be addressed. PMID:22627995

  5. Absorber coatings' degradation

    SciTech Connect

    Moore, S.W.

    1984-01-01

    This report is intended to document some of the Los Alamos efforts that have been carried out under the Department of Energy (DOE) Active Heating and Cooling Materials Reliability, Maintainability, and Exposure Testing program. Funding for these activities is obtained directly from DOE although they represent a variety of projects and coordination with other agencies. Major limitations to the use of solar energy are the uncertain reliability and lifetimes of solar systems. This program is aimed at determining material operating limitations, durabilities, and failure modes such that materials improvements can be made and lifetimes can be extended. Although many active and passive materials and systems are being studied at Los Alamos, this paper will concentrate on absorber coatings and degradation of these coatings.

  6. Physics of Heavily Implanted Single Crystal Complex Oxides

    NASA Astrophysics Data System (ADS)

    Ofan, Avishai

    useful for several microfabrication techniques, in particular we describe the use of these defects for ion slicing of single crystal thin films from bulk crystals and ferroelectric domain patterning by low voltage pulses applied to a scanning force microscope tip. The origin of the rate of anomalously high spatially selective etching of a buried heavily implanted region in complex oxides is found to be closely related to the implantation-induced defects. He+-ion implantation in single-crystal LiNbO3 samples followed by low-temperature anneal and wet etched results in an etch-rate enhancement of 104. This high rate selective etch is crucial for the Crystal Ion Slicing process, a novel technique to fabricate single crystal thin films by slicing them off a bulk crystal. Experiments, using time-resolved optical microscopy and proximal-probe microscopy, show that this enhancement arises from the more rapid etch-solution transport in the thick prismatic planar defect network formed in the implanted region after annealing. Ferroelectric domain patterns are generated in He-implanted single-crystal bulk wafers of LiNbO3 by means of low-voltage pulses applied to a scanning force microscope tip and investigated using piezoresponse force microscopy and selective etching. It is shown that high fluence implantation results in isolation of the near surface region, creating a free-standing-film-like behavior for the layer above the heavily implanted region. At low fluence the implantation damage allows low voltage poling, apparently by vacancy-induced dipole formation. In addition, electrostatic repulsion of the poling-induced buried charges from adjacent domains limits the domain size and depth; this effect results in a uniform domain structures and potentially enables large area nanodomains patterns to be written.

  7. Electrochemically regenerable carbon dioxide absorber

    NASA Technical Reports Server (NTRS)

    Woods, R. R.; Marshall, R. D.; Schubert, F. H.; Heppner, D. B.

    1979-01-01

    Preliminary designs were generated for two electrochemically regenerable carbon dioxide absorber concepts. Initially, an electrochemically regenerable absorption bed concept was designed. This concept incorporated the required electrochemical regeneration components in the absorber design, permitting the absorbent to be regenerated within the absorption bed. This hardware was identified as the electrochemical absorber hardware. The second hardware concept separated the functional components of the regeneration and absorption process. This design approach minimized the extravehicular activity component volume by eliminating regeneration hardware components within the absorber. The electrochemical absorber hardware was extensively characterized for major operating parameters such as inlet carbon dioxide partial pressure, process air flow rate, operational pressure, inlet relative humidity, regeneration current density and absorption/regeneration cycle endurance testing.

  8. Liquid Hydrogen Absorber for MICE

    SciTech Connect

    Ishimoto, S.; Suzuki, S.; Yoshida, M.; Green, Michael A.; Kuno, Y.; Lau, Wing

    2010-05-30

    Liquid hydrogen absorbers for the Muon Ionization Cooling Experiment (MICE) have been developed, and the first absorber has been tested at KEK. In the preliminary test at KEK we have successfully filled the absorber with {approx}2 liters of liquid hydrogen. The measured hydrogen condensation speed was 2.5 liters/day at 1.0 bar. No hydrogen leakage to vacuum was found between 300 K and 20 K. The MICE experiment includes three AFC (absorber focusing coil) modules, each containing a 21 liter liquid hydrogen absorber made of aluminum. The AFC module has safety windows to separate its vacuum from that of neighboring modules. Liquid hydrogen is supplied from a cryocooler with cooling power 1.5 W at 4.2 K. The first absorber will be assembled in the AFC module and installed in MICE at RAL.

  9. Broadband patterned magnetic microwave absorber

    SciTech Connect

    Li, Wei; Wu, Tianlong; Wang, Wei; Guan, Jianguo; Zhai, Pengcheng

    2014-07-28

    It is a tough task to greatly improve the working bandwidth for the traditional flat microwave absorbers because of the restriction of available material parameters. In this work, a simple patterning method is proposed to drastically broaden the absorption bandwidth of a conventional magnetic absorber. As a demonstration, an ultra-broadband microwave absorber with more than 90% absorption in the frequency range of 4–40 GHz is designed and experimentally realized, which has a thin thickness of 3.7 mm and a light weight equivalent to a 2-mm-thick flat absorber. In such a patterned absorber, the broadband strong absorption is mainly originated from the simultaneous incorporation of multiple λ/4 resonances and edge diffraction effects. This work provides a facile route to greatly extend the microwave absorption bandwidth for the currently available absorbing materials.

  10. NuSTAR Observations of Heavily Obscured Quasars at z Is Approximately 0.5

    NASA Technical Reports Server (NTRS)

    Lansbury, G. B.; Alexander, D. M.; Del Moro, A.; Gandhi, P.; Assef, R. J.; Stern, D.; Aird, J.; Ballantyne, D. R.; Balokovic, M.; Bauer, F. E.; Boggs, S. E.; Brandt, W. N.; Christensen, F. E.; Craig, W. W.; Elvis, M.; Grefenstette, B. W.; Hailey, C. J.; Harrison, F. A.; Hickox, R. C.; Koss, M.; LaMassa, S. M.; Luo, B.; Mullaney, J. R.; Teng, S. H.; Urry, C. M.; Zhang, W. W.

    2014-01-01

    We present NuSTAR hard X-ray observations of three Type 2 quasars at z approx. = 0.4-0.5, optically selected from the Sloan Digital Sky Survey. Although the quasars show evidence for being heavily obscured, Compton-thick systems on the basis of the 2-10 keV to [O(sub III)] luminosity ratio and multiwavelength diagnostics, their X-ray absorbing column densities (N(sub H)) are poorly known. In this analysis, (1) we study X-ray emission at greater than 10 keV, where X-rays from the central black hole are relatively unabsorbed, in order to better constrain N(sub H). (2) We further characterize the physical properties of the sources through broad-band near-UV to mid-IR spectral energy distribution analyses. One of the quasars is detected with NuSTAR at greater than 8 keV with a no-source probability of less than 0.1%, and its X-ray band ratio suggests near Compton-thick absorption with N(sub H) is approximately greater than 5 × 10(exp 23) cm(exp -2). The other two quasars are undetected, and have low X-ray to mid-IR luminosity ratios in both the low-energy (2-10 keV) and high-energy (10-40 keV) X-ray regimes that are consistent with extreme, Compton-thick absorption (N(sub H) is approximately greater than 10(exp 24) cm(exp -2)). We find that for quasars at z is approximately 0.5, NuSTAR provides a significant improvement compared to lower energy (less than 10 keV) Chandra and XMM-Newton observations alone, as higher column densities can now be directly constrained.

  11. NuSTAR observations of heavily obscured quasars at z ∼ 0.5

    SciTech Connect

    Lansbury, G. B.; Alexander, D. M.; Moro, A. Del; Gandhi, P.; Aird, J.; Assef, R. J.; Stern, D.; Ballantyne, D. R.; Baloković, M.; Grefenstette, B. W.; Harrison, F. A.; Bauer, F. E.; Boggs, S. E.; Brandt, W. N.; Christensen, F. E.; Craig, W. W.; Elvis, M.; Hailey, C. J.; Hickox, R. C.; Koss, M.; and others

    2014-04-10

    We present NuSTAR hard X-ray observations of three Type 2 quasars at z ≈ 0.4-0.5, optically selected from the Sloan Digital Sky Survey. Although the quasars show evidence for being heavily obscured, Compton-thick systems on the basis of the 2-10 keV to [O III] luminosity ratio and multiwavelength diagnostics, their X-ray absorbing column densities (N {sub H}) are poorly known. In this analysis, (1) we study X-ray emission at >10 keV, where X-rays from the central black hole are relatively unabsorbed, in order to better constrain N {sub H}. (2) We further characterize the physical properties of the sources through broad-band near-UV to mid-IR spectral energy distribution analyses. One of the quasars is detected with NuSTAR at >8 keV with a no-source probability of <0.1%, and its X-ray band ratio suggests near Compton-thick absorption with N {sub H} ≳ 5 × 10{sup 23} cm{sup –2}. The other two quasars are undetected, and have low X-ray to mid-IR luminosity ratios in both the low-energy (2-10 keV) and high-energy (10-40 keV) X-ray regimes that are consistent with extreme, Compton-thick absorption (N {sub H} ≳ 10{sup 24} cm{sup –2}). We find that for quasars at z ∼ 0.5, NuSTAR provides a significant improvement compared to lower energy (<10 keV) Chandra and XMM-Newton observations alone, as higher column densities can now be directly constrained.

  12. Plants absorb heavy metals

    SciTech Connect

    Parry, J.

    1995-02-01

    Decontamination of heavy metals-polluted soils remains one of the most intractable problems of cleanup technology. Currently available techniques include extraction of the metals by physical and chemical means, such as acid leaching and electroosmosis, or immobilization by vitrification. There are presently no techniques for cleanup which are low cost and retain soil fertility after metals removal. But a solution to the problem could be on the horizon. A small but growing number of plants native to metalliferous soils are known to be capable of accumulating extremely high concentrations of metals in their aboveground portions. These hyperaccumulators, as they are called, contain up to 1,000 times larger metal concentrations in their aboveground parts than normal species. Their distribution is global, including many different families of flowering plants of varying growth forms, from herbaceous plants to trees. Hyperaccumulators absorb metals they do not need for their own nutrition. The metals are accumulated in the leaf and stem vacuoles, and to a lesser extent in the roots.

  13. Context of Carbonate Rocks in Heavily Eroded Martian Terrain

    NASA Technical Reports Server (NTRS)

    2008-01-01

    The color coding on this composite image of an area about 20 kilometers (12 miles) wide on Mars is based on infrared spectral information interpreted as evidence of various minerals present. Carbonate, which is indicative of a wet and non-acidic history, occurs in very small patches of exposed rock appearing green in this color representation, such as near the lower right corner.

    The scene is heavily eroded terrain to the west of a small canyon in the Nili Fossae region of Mars. It was one of the first areas where researchers on the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) science team detected carbonate in Mars rocks. The spectral information comes from infrared imaging by CRISM, one of six science instruments on NASA's Mars Reconnaissance Orbiter. That coloring is overlaid on a grayscale image from the same orbiter's Context Camera.

    The uppermost capping rock unit (purple) is underlain successively by banded olivine-bearing rocks (yellow) and rocks bearing iron-magnesium smectite clay (blue). Where the olivine is a greenish hue, it has been partially altered by interaction with water. The carbonate and olivine occupy the same level in the stratigraphy, and it is thought that the carbonate formed by aqueous alteration of olivine. The channel running from upper left to lower right through the image and eroding into the layers of bedrock testifies to the past presence of water in this region. That some of the channels are closely associated with carbonate (lower right) indicates that waters interacting with the carbonate were neutral to alkaline because acidic waters would have dissolved the carbonate.

    Information for the color coding came from CRISM images catalogued as FRT0000B438, FRT0000A4FC, and FRT00003E12. This composite was made using 2.38-micrometer-wavelenghth data as red, 1.80 micrometer as green and 1.15 micrometer as blue.

    The base black-and-white image, acquired at a resolution of 5 meters (16 feet) per

  14. Energy absorber for the CETA

    NASA Astrophysics Data System (ADS)

    Wesselski, Clarence J.

    1994-05-01

    The energy absorber that was developed for the CETA (Crew Equipment and Translation Aid) on Space Station Freedom is a metal on metal frictional type and has a load regulating feature that prevents excessive stroking loads from occurring while in operation. This paper highlights some of the design and operating aspects and the testing of this energy absorber.

  15. Energy absorber for the CETA

    NASA Technical Reports Server (NTRS)

    Wesselski, Clarence J.

    1994-01-01

    The energy absorber that was developed for the CETA (Crew Equipment and Translation Aid) on Space Station Freedom is a metal on metal frictional type and has a load regulating feature that prevents excessive stroking loads from occurring while in operation. This paper highlights some of the design and operating aspects and the testing of this energy absorber.

  16. Metal-shearing energy absorber

    NASA Technical Reports Server (NTRS)

    Fay, R. J.; Wittrock, E. P.

    1971-01-01

    Device, consisting of tongue of thin aluminum alloy strip, pull tab, slotted steel plate which serves as cutter, and steel buckle, absorbs mechanical energy when its ends are subjected to tensile loading. Device is applicable as auxiliary shock absorbing anchor for automobile and airplane safety belts.

  17. Leaf absorbance and photosynthesis

    NASA Technical Reports Server (NTRS)

    Schurer, Kees

    1994-01-01

    The absorption spectrum of a leaf is often thought to contain some clues to the photosynthetic action spectrum of chlorophyll. Of course, absorption of photons is needed for photosynthesis, but the reverse, photosynthesis when there is absorption, is not necessarily true. As a check on the existence of absorption limits we measured spectra for a few different leaves. Two techniques for measuring absorption have been used, viz. the separate determination of the diffuse reflectance and the diffuse transmittance with the leaf at a port of an integrating sphere and the direct determination of the non-absorbed fraction with the leaf in the sphere. In a cross-check both methods yielded the same results for the absorption spectrum. The spectrum of a Fuchsia leaf, covering the short-wave region from 350 to 2500 nm, shows a high absorption in UV, blue and red, the well known dip in the green and a steep fall-off at 700 nm. Absorption drops to virtually zero in the near infrared, with subsequent absorptions, corresponding to the water absorption bands. In more detailed spectra, taken at 5 nm intervals with a 5 nm bandwidth, differences in chlorophyll content show in the different depths of the dip around 550 nm and in a small shift of the absorption edge at 700 nm. Spectra for Geranium (Pelargonium zonale) and Hibiscus (with a higher chlorophyll content) show that the upper limit for photosynthesis can not be much above 700 nm. No evidence, however, is to be seen of a lower limit for photosynthesis and, in fact, some experiments down to 300 nm still did not show a decrease of the absorption although it is well recognized that no photosynthesis results with 300 nm wavelengths.

  18. Visible light broadband perfect absorbers

    NASA Astrophysics Data System (ADS)

    Jia, X. L.; Meng, Q. X.; Yuan, C. X.; Zhou, Z. X.; Wang, X. O.

    2016-03-01

    The visible light broadband perfect absorbers based on the silver (Ag) nano elliptical disks and holes array are studied using finite difference time domain simulations. The semiconducting indium silicon dioxide thin film is introduced as the space layer in this sandwiched structure. Utilizing the asymmetrical geometry of the structures, polarization sensitivity for transverse electric wave (TE)/transverse magnetic wave (TM) and left circular polarization wave (LCP)/right circular polarization wave (RCP) of the broadband absorption are gained. The absorbers with Ag nano disks and holes array show several peaks absorbance of 100% by numerical simulation. These simple and flexible perfect absorbers are particularly desirable for various potential applications including the solar energy absorber.

  19. Grown-in precipitates in heavily phosphorus-doped Czochralski silicon

    NASA Astrophysics Data System (ADS)

    Zeng, Yuheng; Ma, Xiangyang; Chen, Jiahe; Song, Weijie; Wang, Weiyan; Gong, Longfei; Tian, Daxi; Yang, Deren

    2012-02-01

    Through comparing the oxygen precipitation in the heavily and lightly phosphorus (P)-doped Czochralski silicon (CZ Si) specimens subjected to the simulated cooling processes of silicon ingot, we researched the influences of heavily P doping on grown-in precipitates by preferential etching and transmission electron microscopy (TEM). It was found that grown-in precipitates were more significant in heavily P-doped CZ Si than in lightly one. Most grown-in precipitates in heavily P-doped CZ Si were generated at (800-600) °C. The significant grown-in oxygen precipitates in the heavily P-doped CZ Si would change the density and morphology of oxygen precipitation. TEM examination revealed that the grown-in precipitates in heavily P-doped CZ Si were amorphous oxygen precipitates composed of tiny precipitates in essential. Although more or less phosphorus may be incorporated in the grown-in precipitates, however, phosphorus cannot be detected so far. We further confirmed that extending annealing at 550 °C produced significant silicon phosphide (SiP) precipitation in heavily P-doped CZ Si. Summarily, enhancement of grown-in oxygen precipitates was attributed to SiP precipitation and high-concentration vacancy, tentatively. Nonetheless, further investigation on the essential of grown-in precipitates in heavily P-doped CZ Si is worthy.

  20. thin films as absorber

    NASA Astrophysics Data System (ADS)

    González, J. O.; Shaji, S.; Avellaneda, D.; Castillo, G. A.; Das Roy, T. K.; Krishnan, B.

    2014-09-01

    Photovoltaic structures were prepared using AgSb(S x Se1- x )2 as absorber and CdS as window layer at various conditions via a hybrid technique of chemical bath deposition and thermal evaporation followed by heat treatments. Silver antimony sulfo selenide thin films [AgSb(S x Se1- x )2] were prepared by heating multilayers of sequentially deposited Sb2S3/Ag dipped in Na2SeSO3 solution, glass/Sb2S3/Ag/Se. For this, Sb2S3 thin films were deposited from a chemical bath containing SbCl3 and Na2S2O3. Then, Ag thin films were thermally evaporated on glass/Sb2S3, followed by selenization by dipping in an acidic solution of Na2SeSO3. The duration of dipping was varied as 3, 4 and 5 h. Two different heat treatments, one at 350 °C for 20 min in vacuum followed by a post-heat treatment at 325 °C for 2 h in Ar, and the other at 350 °C for 1 h in Ar, were applied to the multilayers of different configurations. X-ray diffraction results showed the formation of AgSb(S x Se1- x )2 thin films as the primary phase and AgSb(S,Se)2 and Sb2S3 as secondary phases. Morphology and elemental detection were done by scanning electron microscopy and energy dispersive X-ray analysis. X-ray photoelectron spectroscopic studies showed the depthwise composition of the films. Optical properties were determined by UV-vis-IR transmittance and reflection spectral analysis. AgSb(S x Se1- x )2 formed at different conditions was incorporated in PV structures glass/FTO/CdS/AgSb(S x Se1- x )2/C/Ag. Chemically deposited post-annealed CdS thin films of various thicknesses were used as window layer. J- V characteristics of the cells were measured under dark and AM1.5 illumination. Analysis of the J- V characteristics resulted in the best solar cell parameters of V oc = 520 mV, J sc = 9.70 mA cm-2, FF = 0.50 and η = 2.7 %.

  1. The nature of the torus in the heavily obscured AGN Markarian 3: an X-ray study

    NASA Astrophysics Data System (ADS)

    Guainazzi, M.; Risaliti, G.; Awaki, H.; Arevalo, P.; Bauer, F. E.; Bianchi, S.; Boggs, S. E.; Brandt, W. N.; Brightman, M.; Christensen, F. E.; Craig, W. W.; Forster, K.; Hailey, C. J.; Harrison, F.; Koss, M.; Longinotti, A.; Markwardt, C.; Marinucci, A.; Matt, G.; Reynolds, C. S.; Ricci, C.; Stern, D.; Svoboda, J.; Walton, D.; Zhang, W.

    2016-08-01

    In this paper we report the results of an X-ray monitoring campaign on the heavily obscured Seyfert galaxy Markarian 3 carried out between the fall of 2014 and the spring of 2015 with NuSTAR, Suzaku and XMM-Newton. The hard X-ray spectrum of Markarian 3 is variable on all the time scales probed by our campaign, down to a few days. The observed continuum variability is due to an intrinsically variable primary continuum seen in transmission through a large, but still Compton-thin column density (N_H~0.8-1.1$\\times$10$^{24}$ cm$^{-2}$). If arranged in a spherical-toroidal geometry, the Compton scattering matter has an opening angle ~66 degrees and is seen at a grazing angle through its upper rim (inclination angle ~70 degrees). We report a possible occultation event during the 2014 campaign. If the torus is constituted by a system of clouds sharing the same column density, this event allows us to constrain their number (17$\\pm$5) and individual column density, [~(4.9$\\pm$1.5)$\\times$10$^{22}$ cm$^{-2}$]. The comparison of IR and X-ray spectroscopic results with state-of-the art "torus" models suggests that at least two thirds of the X-ray obscuring gas volume might be located within the dust sublimation radius. We report also the discovery of an ionized absorber, characterised by variable resonant absorption lines due to He- and H-like iron. This discovery lends support to the idea that moderate column density absorbers could be due to clouds evaporated at the outer surface of the torus, possibly accelerated by the radiation pressure due to the central AGN emission leaking through the patchy absorber.

  2. The nature of the torus in the heavily obscured AGN Markarian 3: an X-ray study

    NASA Astrophysics Data System (ADS)

    Guainazzi, M.; Risaliti, G.; Awaki, H.; Arevalo, P.; Bauer, F. E.; Bianchi, S.; Boggs, S. E.; Brandt, W. N.; Brightman, M.; Christensen, F. E.; Craig, W. W.; Forster, K.; Hailey, C. J.; Harrison, F.; Koss, M.; Longinotti, A.; Markwardt, C.; Marinucci, A.; Matt, G.; Reynolds, C. S.; Ricci, C.; Stern, D.; Svoboda, J.; Walton, D.; Zhang, W.

    2016-08-01

    In this paper, we report the results of an X-ray monitoring campaign on the heavily obscured Seyfert galaxy, Markarian 3, carried out between the fall of 2014 and the spring of 2015 with NuSTAR, Suzaku and XMM-Newton. The hard X-ray spectrum of Markarian 3 is variable on all the time-scales probed by our campaign, down to a few days. The observed continuum variability is due to an intrinsically variable primary continuum seen in transmission through a large, but still Compton-thin column density (NH ˜ 0.8-1.1 × 1024 cm-2). If arranged in a spherical-toroidal geometry, the Compton scattering matter has an opening angle ≃66°, and is seen at a grazing angle through its upper rim (inclination angle ≃70°). We report a possible occultation event during the 2014 campaign. If the torus is constituted by a system of clouds sharing the same column density, this event allows us to constrain their number (17 ± 5) and individual column density, [≃ (4.9 ± 1.5) × 1022 cm-2]. The comparison of IR and X-ray spectroscopic results with state-of-the art `torus' models suggests that at least two-thirds of the X-ray obscuring gas volume might be located within the dust sublimation radius. We report also the discovery of an ionized absorber, characterized by variable resonant absorption lines due to He- and H-like iron. This discovery lends support to the idea that moderate column density absorbers could be due to clouds evaporated at the outer surface of the torus, possibly accelerated by the radiation pressure due to the central AGN emission leaking through the patchy absorber.

  3. Absorbent product to absorb fluids. [for collection of human wastes

    NASA Technical Reports Server (NTRS)

    Dawn, F. S.; Correale, J. V. (Inventor)

    1982-01-01

    A multi-layer absorbent product for use in contact with the skin to absorb fluids is discussed. The product utilizes a water pervious facing layer for contacting the skin, overlayed by a first fibrous wicking layer, the wicking layer preferably being of the one-way variety in which fluid or liquid is moved away from the facing layer. The product further includes a first container section defined by inner and outer layer of a water pervious wicking material between which is disposed a first absorbent mass. A second container section defined by inner and outer layers between which is disposed a second absorbent mass and a liquid impermeable/gas permeable layer. Spacesuit applications are discussed.

  4. Countercurrent flow absorber and desorber

    DOEpatents

    Wilkinson, William H.

    1984-01-01

    Countercurrent flow absorber and desorber devices are provided for use in absorption cycle refrigeration systems and thermal boosting systems. The devices have increased residence time and surface area resulting in improved heat and mass transfer characteristics. The apparatuses may be incorporated into open cycle thermal boosting systems in which steam serves both as the refrigerant vapor which is supplied to the absorber section and as the supply of heat to drive the desorber section of the system.

  5. Hyperuniformity of critical absorbing states.

    PubMed

    Hexner, Daniel; Levine, Dov

    2015-03-20

    The properties of the absorbing states of nonequilibrium models belonging to the conserved directed percolation universality class are studied. We find that, at the critical point, the absorbing states are hyperuniform, exhibiting anomalously small density fluctuations. The exponent characterizing the fluctuations is measured numerically, a scaling relation to other known exponents is suggested, and a new correlation length relating to this ordering is proposed. These results may have relevance to photonic band-gap materials. PMID:25839254

  6. Hyperuniformity of Critical Absorbing States

    NASA Astrophysics Data System (ADS)

    Hexner, Daniel; Levine, Dov

    2015-03-01

    The properties of the absorbing states of nonequilibrium models belonging to the conserved directed percolation universality class are studied. We find that, at the critical point, the absorbing states are hyperuniform, exhibiting anomalously small density fluctuations. The exponent characterizing the fluctuations is measured numerically, a scaling relation to other known exponents is suggested, and a new correlation length relating to this ordering is proposed. These results may have relevance to photonic band-gap materials.

  7. Packed Alumina Absorbs Hypergolic Vapors

    NASA Technical Reports Server (NTRS)

    Thomas, J. J.; Mauro, D. M.

    1984-01-01

    Beds of activated alumina effective as filters to remove hypergolic vapors from gas streams. Beds absorb such substances as nitrogen oxides and hydrazines and may also absorb acetylene, ethylene, hydrogen sulfide, benzene, butadiene, butene, styrene, toluene, and xoylene. Bed has no moving parts such as pumps, blowers and mixers. Reliable and energy-conservative. Bed readily adapted to any size from small portable units for use where little vapor release is expected to large stationary units for extensive transfer operations.

  8. Countercurrent flow absorber and desorber

    DOEpatents

    Wilkinson, W.H.

    1984-10-16

    Countercurrent flow absorber and desorber devices are provided for use in absorption cycle refrigeration systems and thermal boosting systems. The devices have increased residence time and surface area resulting in improved heat and mass transfer characteristics. The apparatuses may be incorporated into open cycle thermal boosting systems in which steam serves both as the refrigerant vapor which is supplied to the absorber section and as the supply of heat to drive the desorber section of the system. 9 figs.

  9. Physics of heavily doped silicon and solar-cell parameter measurement

    NASA Technical Reports Server (NTRS)

    Lindholm, F. A.

    1984-01-01

    A study of the physics of heavily doped silicon and solar cell parameter measurement was undertaken. The parameters investigated were energy gap, lifetime, recombination velocity, diffusivity, mobility and if N or P is high.

  10. Carbon Absorber Retrofit Equipment (CARE)

    SciTech Connect

    Klein, Eric

    2015-12-23

    During Project DE-FE0007528, CARE (Carbon Absorber Retrofit Equipment), Neumann Systems Group (NSG) designed, installed and tested a 0.5MW NeuStream® carbon dioxide (CO2) capture system using the patented NeuStream® absorber equipment and concentrated (6 molal) piperazine (PZ) as the solvent at Colorado Springs Utilities’ (CSU’s) Martin Drake pulverized coal (PC) power plant. The 36 month project included design, build and test phases. The 0.5MW NeuStream® CO2 capture system was successfully tested on flue gas from both coal and natural gas combustion sources and was shown to meet project objectives. Ninety percent CO2 removal was achieved with greater than 95% CO2product purity. The absorbers tested support a 90% reduction in absorber volume compared to packed towers and with an absorber parasitic power of less than 1% when configured for operation with a 550MW coal plant. The preliminary techno-economic analysis (TEA) performed by the Energy and Environmental Research Center (EERC) predicted an over-the-fence cost of $25.73/tonne of CO2 captured from a sub-critical PC plant.

  11. Mushroom plasmonic metamaterial infrared absorbers

    NASA Astrophysics Data System (ADS)

    Ogawa, Shinpei; Fujisawa, Daisuke; Hata, Hisatoshi; Uetsuki, Mitsuharu; Misaki, Koji; Kimata, Masafumi

    2015-01-01

    There has been a considerable amount of interest in the development of various types of electromagnetic wave absorbers for use in different wavelength ranges. In particular, infrared (IR) absorbers with wavelength selectivity can be applied to advanced uncooled IR sensors, which would be capable of identifying objects through their radiation spectrum. In the present study, mushroom plasmonic metamaterial absorbers (MPMAs) for the IR wavelength region were designed and fabricated. The MPMAs consist of a periodic array of thin metal micropatches connected to a thin metal plate with narrow silicon (Si) posts. A Si post height of 200 nm was achieved by isotropic XeF2 etching of a thin Si layer sandwiched between metal plates. This fabrication procedure is relatively simple and is consistent with complementary metal oxide semiconductor technology. The absorption spectra of the fabricated MPMAs were experimentally measured. In addition, theoretical calculations of their absorption properties were conducted using rigorous coupled wave analysis. Both the calculated and measured absorbance results demonstrated that these MPMAs can realize strong selective absorption at wavelengths beyond the period of the array by varying the micropatch width. Absorbance values greater than 90% were achieved. Dual- or single-mode absorption can also be selected by varying the width of the Si posts. Pixel structures using such MPMAs could be used as high responsivity, high resolution and fast uncooled IR sensors.

  12. Additive manufacturing of RF absorbers

    NASA Astrophysics Data System (ADS)

    Mills, Matthew S.

    The ability of additive manufacturing techniques to fabricate integrated electromagnetic absorbers tuned for specific radio frequency bands within structural composites allows for unique combinations of mechanical and electromagnetic properties. These composites and films can be used for RF shielding of sensitive electromagnetic components through in-plane and out-of-plane RF absorption. Structural composites are a common building block of many commercial platforms. These platforms may be placed in situations in which there is a need for embedded RF absorbing properties along with structural properties. Instead of adding radar absorbing treatments to the external surface of existing structures, which adds increased size, weight and cost; it could prove to be advantageous to integrate the microwave absorbing properties directly into the composite during the fabrication process. In this thesis, a method based on additive manufacturing techniques of composites structures with prescribed electromagnetic loss, within the frequency range 1 to 26GHz, is presented. This method utilizes screen printing and nScrypt micro dispensing to pattern a carbon based ink onto low loss substrates. The materials chosen for this study will be presented, and the fabrication technique that these materials went through to create RF absorbing structures will be described. The calibration methods used, the modeling of the RF structures, and the applications in which this technology can be utilized will also be presented.

  13. Mushroom plasmonic metamaterial infrared absorbers

    SciTech Connect

    Ogawa, Shinpei Fujisawa, Daisuke; Hata, Hisatoshi; Uetsuki, Mitsuharu; Misaki, Koji; Kimata, Masafumi

    2015-01-26

    There has been a considerable amount of interest in the development of various types of electromagnetic wave absorbers for use in different wavelength ranges. In particular, infrared (IR) absorbers with wavelength selectivity can be applied to advanced uncooled IR sensors, which would be capable of identifying objects through their radiation spectrum. In the present study, mushroom plasmonic metamaterial absorbers (MPMAs) for the IR wavelength region were designed and fabricated. The MPMAs consist of a periodic array of thin metal micropatches connected to a thin metal plate with narrow silicon (Si) posts. A Si post height of 200 nm was achieved by isotropic XeF{sub 2} etching of a thin Si layer sandwiched between metal plates. This fabrication procedure is relatively simple and is consistent with complementary metal oxide semiconductor technology. The absorption spectra of the fabricated MPMAs were experimentally measured. In addition, theoretical calculations of their absorption properties were conducted using rigorous coupled wave analysis. Both the calculated and measured absorbance results demonstrated that these MPMAs can realize strong selective absorption at wavelengths beyond the period of the array by varying the micropatch width. Absorbance values greater than 90% were achieved. Dual- or single-mode absorption can also be selected by varying the width of the Si posts. Pixel structures using such MPMAs could be used as high responsivity, high resolution and fast uncooled IR sensors.

  14. Nonventing, Regenerable, Lightweight Heat Absorber

    NASA Technical Reports Server (NTRS)

    Izenson, Michael G.; Chen, Weibo

    2008-01-01

    A lightweight, regenerable heat absorber (RHA), developed for rejecting metabolic heat from a space suit, may also be useful on Earth for short-term cooling of heavy protective garments. Unlike prior space-suit-cooling systems, a system that includes this RHA does not vent water. The closed system contains water reservoirs, tubes through which water is circulated to absorb heat, an evaporator, and an absorber/radiator. The radiator includes a solution of LiCl contained in a porous material in titanium tubes. The evaporator cools water that circulates through a liquid-cooled garment. Water vapor produced in the evaporator enters the radiator tubes where it is absorbed into the LiCl solution, releasing heat. Much of the heat of absorption is rejected to the environment via the radiator. After use, the RHA is regenerated by heating it to a temperature of 100 C for about 2 hours to drive the absorbed water back to the evaporator. A system including a prototype of the RHA was found to be capable of maintaining a temperature of 20 C while removing heat at a rate of 200 W for 6 hours.

  15. Measurement of carrier transport and recombination parameter in heavily doped silicon

    NASA Technical Reports Server (NTRS)

    Swanson, Richard M.

    1986-01-01

    The minority carrier transport and recombination parameters in heavily doped bulk silicon were measured. Both Si:P and Si:B with bulk dopings from 10 to the 17th and 10 to the 20th power/cu cm were studied. It is shown that three parameters characterize transport in bulk heavily doped Si: the minority carrier lifetime tau, the minority carrier mobility mu, and the equilibrium minority carrier density of n sub 0 and p sub 0 (in p-type and n-type Si respectively.) However, dc current-voltage measurements can never measure all three of these parameters, and some ac or time-transient experiment is required to obtain the values of these parameters as a function of dopant density. Using both dc electrical measurements on bipolar transitors with heavily doped base regions and transients optical measurements on heavily doped bulk and epitaxially grown samples, lifetime, mobility, and bandgap narrowing were measured as a function of both p and n type dopant densities. Best fits of minority carrier mobility, bandgap narrowing and lifetime as a function of doping density (in the heavily doped range) were constructed to allow accurate modeling of minority carrier transport in heavily doped Si.

  16. Damage tolerant light absorbing material

    DOEpatents

    Lauf, R.J.; Hamby, C. Jr.; Akerman, M.A.; Seals, R.D.

    1993-09-07

    A light absorbing article comprised of a composite of carbon-bonded carbon fibers, is prepared by: blending carbon fibers with a carbonizable organic powder to form a mixture; dispersing the mixture into an aqueous slurry; vacuum molding the aqueous slurry to form a green article; drying and curing the green article to form a cured article; and, carbonizing the cured article at a temperature of at least about 1000 C to form a carbon-bonded carbon fiber light absorbing composite article having a bulk density less than 1 g/cm[sup 3]. 9 figures.

  17. Damage tolerant light absorbing material

    DOEpatents

    Lauf, Robert J.; Hamby, Jr., Clyde; Akerman, M. Alfred; Seals, Roland D.

    1993-01-01

    A light absorbing article comprised of a composite of carbon-bonded carbon fibers, prepared by: blending carbon fibers with a carbonizable organic powder to form a mixture; dispersing the mixture into an aqueous slurry; vacuum molding the aqueous slurry to form a green article; drying and curing the green article to form a cured article; and, carbonizing the cured article at a temperature of at least about 1000.degree. C. to form a carbon-bonded carbon fiber light absorbing composite article having a bulk density less than 1 g/cm.sup.3.

  18. Adaptive inertial shock-absorber

    NASA Astrophysics Data System (ADS)

    Faraj, Rami; Holnicki-Szulc, Jan; Knap, Lech; Seńko, Jarosław

    2016-03-01

    This paper introduces and discusses a new concept of impact absorption by means of impact energy management and storage in dedicated rotating inertial discs. The effectiveness of the concept is demonstrated in a selected case-study involving spinning management, a recently developed novel impact-absorber. A specific control technique performed on this device is demonstrated to be the main source of significant improvement in the overall efficiency of impact damping process. The influence of various parameters on the performance of the shock-absorber is investigated. Design and manufacturing challenges and directions of further research are formulated.

  19. Counterflow absorber for an absorption refrigeration system

    DOEpatents

    Reimann, Robert C.

    1984-01-01

    An air-cooled, vertical tube absorber for an absorption refrigeration system is disclosed. Strong absorbent solution is supplied to the top of the absorber and refrigerant vapor is supplied to the bottom of the absorber to create a direct counterflow of refrigerant vapor and absorbent solution in the absorber. The refrigeration system is designed so that the volume flow rate of refrigerant vapor in the tubes of the absorber is sufficient to create a substantially direct counterflow along the entire length of each tube in the absorber. This provides several advantages for the absorber such as higher efficiency and improved heat transfer characteristics, and allows improved purging of non-condensibles from the absorber.

  20. Oil and fat absorbing polymers

    NASA Technical Reports Server (NTRS)

    Marsh, H. E., Jr. (Inventor)

    1977-01-01

    A method is described for forming a solid network polymer having a minimal amount of crosslinking for use in absorbing fats and oils. The polymer remains solid at a swelling ratio in oil or fat of at least ten and provides an oil absorption greater than 900 weight percent.

  1. [Study of new blended chemical absorbents to absorb CO2].

    PubMed

    Wang, Jin-Lian; Fang, Meng-Xiang; Yan, Shui-Ping; Luo, Zhong-Yang; Cen, Ke-Fa

    2007-11-01

    Three kinds of blended absorbents were investigated on bench-scale experimental bench according to absorption rate and regeneration grade to select a reasonable additive concentration. The results show that, among methyldiethanolamine (MDEA) and piperazine (PZ) mixtures, comparing MDEA : PZ = 1 : 0.4 (m : m) with MDEA : PZ = 1 : 0.2 (m : m), the absorption rate is increased by about 70% at 0.2 mol x mol(-1). When regeneration lasting for 40 min, regeneration grade of blended absorbents with PZ concentration of 0.2, 0.4, and 0.8 is decreased to 83.06%, 77.77% and 76.67% respectively while 91.04% for PZ concentration of 0. MDEA : PZ = 1 : 0.4(m : m) is a suitable ratio for MDEA/PZ mixtures as absorption and regeneration properties of the blended absorbents are all improved. The aqueous blends with 10% primary amines and 2% tertiary amines could keep high CO2 absorption rate, and lower regeneration energy consumption. Adding 2% 2-Amino-2-methyl-1-propanol (AMP) to 10% diethanolamine (DEA), the blended amine solvents have an advantage in absorption and regeneration properties over other DEA/AMP mixtures. Blended solvents, which consist of a mixture of primary amines with a small amount of tertiary amines, have the highest absorption rate among the three. And mixed absorbents of secondary amines and a small amount of sterically hindered amines have the best regeneration property. To combine absorption and regeneration properties, blends with medium activator addition to tertiary amines are competitive. PMID:18290495

  2. Enhanced diffusion of oxygen depending on Fermi level position in heavily boron-doped silicon

    SciTech Connect

    Torigoe, Kazuhisa Fujise, Jun; Ono, Toshiaki; Nakamura, Kozo

    2014-11-21

    The enhanced diffusivity of oxygen in heavily boron doped silicon was obtained by analyzing oxygen out-diffusion profile changes found at the interface between a lightly boron-doped silicon epitaxial layer and a heavily boron-doped silicon substrate by secondary ion mass spectrometry. It was found that the diffusivity is proportional to the square root of boron concentration in the range of 10{sup 18 }cm{sup −3}–10{sup 19 }cm{sup −3} at temperatures from 750 °C to 950 °C. The model based on the diffusion of oxygen dimers in double positive charge state could explain the enhanced diffusion. We have concluded that oxygen diffusion enhanced in heavily boron-doped silicon is attributed to oxygen dimers ionized depending on Fermi level position.

  3. Case report: Ovarian cavernous haemangioma presenting as a heavily calcified adnexal mass.

    PubMed

    Kim, M Y; Rha, S E; Oh, S N; Lee, Y J; Jung, E S; Byun, J Y

    2008-11-01

    Haemangioma is an extremely rare tumour of the ovary. We describe the CT and MRI findings of a heavily calcified ovarian haemangioma in a 69-year-old woman presenting with adnexal torsion. CT showed a well-circumscribed mass with extensive punctate calcifications, located posterior to the uterus. MR images showed dark signal intensities of the mass on both T(1) and T(2) weighted images, with poor enhancement of the mass on contrast-enhanced T(1) weighted images. MR images also demonstrated a beak-like protrusion from the adnexal mass, representing the adnexal torsion. This is the first case report of a heavily calcified ovarian haemangioma in the English literature. Although rare, ovarian haemangioma should be included in the differential diagnosis of a heavily calcified adnexal mass. PMID:18941040

  4. Thermophotovoltaic energy conversion system having a heavily doped n-type region

    DOEpatents

    DePoy, David M.; Charache, Greg W.; Baldasaro, Paul F.

    2000-01-01

    A thermophotovoltaic (TPV) energy conversion semiconductor device is provided which incorporates a heavily doped n-type region and which, as a consequence, has improved TPV conversion efficiency. The thermophotovoltaic energy conversion device includes an emitter layer having first and second opposed sides and a base layer in contact with the first side of the emitter layer. A highly doped n-type cap layer is formed on the second side of the emitter layer or, in another embodiment, a heavily doped n-type emitter layer takes the place of the cap layer.

  5. Energy-Absorbing, Lightweight Wheels

    NASA Technical Reports Server (NTRS)

    Waydo, Peter

    2003-01-01

    Improved energy-absorbing wheels are under development for use on special-purpose vehicles that must traverse rough terrain under conditions (e.g., extreme cold) in which rubber pneumatic tires would fail. The designs of these wheels differ from those of prior non-pneumatic energy-absorbing wheels in ways that result in lighter weights and more effective reduction of stresses generated by ground/wheel contact forces. These wheels could be made of metals and/or composite materials to withstand the expected extreme operating conditions. As shown in the figure, a wheel according to this concept would include an isogrid tire connected to a hub via spring rods. The isogrid tire would be a stiff, lightweight structure typically made of aluminum. The isogrid aspect of the structure would both impart stiffness and act as a traction surface. The hub would be a thin-walled body of revolution having a simple or compound conical or other shape chosen for structural efficiency. The spring rods would absorb energy and partially isolate the hub and the supported vehicle from impact loads. The general spring-rod configuration shown in the figure was chosen because it would distribute contact and impact loads nearly evenly around the periphery of the hub, thereby helping to protect the hub against damage that would otherwise be caused by large loads concentrated onto small portions of the hub.

  6. The Swift BAT Survey Detects Two Optical Broad Line, X-Ray Heavily Obscured Active Galaxies: NVSS 193013+341047 and IRAS 05218-1212

    NASA Astrophysics Data System (ADS)

    Hogg, J. Drew; Winter, Lisa M.; Mushotzky, Richard F.; Reynolds, Christopher S.; Trippe, Margaret

    2012-06-01

    The Swift Burst Alert Telescope (BAT) is discovering interesting new objects while monitoring the sky in the 14-195 keV band. Here we present the X-ray properties and spectral energy distributions (SEDs) for two unusual active galactic nucleus sources. Both NVSS 193013+341047 and IRAS 05218-1212 are absorbed, Compton-thin, but heavily obscured (N H ~ 1023 cm-2), X-ray sources at redshifts <0.1. The SEDs reveal these galaxies to be very red, with high extinction in the optical and UV. A similar SED is seen for the extremely red objects (EROs) detected in the higher redshift universe. This suggests that these unusual BAT-detected sources are a low-redshift (z Lt 1) analog to EROs, which recent evidence suggests are a class of the elusive type II quasars. Studying the multi-wavelength properties of these sources may reveal the properties of their high-redshift counterparts.

  7. Shock absorber operates over wide range

    NASA Technical Reports Server (NTRS)

    Creasy, W. K.; Jones, J. C.

    1965-01-01

    Piston-type hydraulic shock absorber, with a metered damping system, operates over a wide range of kinetic energy loading rates. It is used for absorbing shock and vibration on mounted machinery and heavy earth-moving equipment.

  8. Becoming a Heavily Tattooed Young Body: From a Bodily Experience to a Body Project

    ERIC Educational Resources Information Center

    Ferreira, Vitor Sérgio

    2014-01-01

    Why some young people start to tattoo their bodies? And why some of them keep going on with this practice, until having all body tattooed? What doing so means to them? These are some of the questions that underlie a qualitative research project carried out in Portugal on heavily tattooed young people. In this article, the author discusses their…

  9. 21 CFR 872.6050 - Saliva absorber.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Saliva absorber. 872.6050 Section 872.6050 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL... absorber is a device made of paper or cotton intended to absorb moisture from the oral cavity during...

  10. 21 CFR 872.6050 - Saliva absorber.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Saliva absorber. 872.6050 Section 872.6050 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL... absorber is a device made of paper or cotton intended to absorb moisture from the oral cavity during...

  11. Improving the laboratory monitoring of absorbent oil

    SciTech Connect

    V.S. Shved; S.S. Sychev; I.V. Safina; S.A. Klykov

    2009-05-15

    The performance of absorbent coal tar oil is analyzed as a function of the constituent and group composition. The qualitative and quantitative composition of the oil that ensures the required absorbent properties is determined. Operative monitoring may be based on absorbent characteristics that permit regulation of the beginning and end of regeneration.

  12. Embedded absorbers for helicopter rotor lag damping

    NASA Astrophysics Data System (ADS)

    Byers, Lynn; Gandhi, Farhan

    2009-09-01

    Radial and chordwise damped vibration absorbers embedded in the rotor blade are compared for rotor lag damping augmentation. Results show that the radial absorber is more effective in transferring damping to the rotor blade lag mode. The chordwise absorber needs to be at a more outboard location and have a larger mass to introduce levels of lag damping comparable to that introduced by the radial absorber. The 1/rev amplitude of a chordwise absorber at the blade tip, per degree of blade lead-lag motion in forward flight, is of the order of 35% of the blade chord, and such a stroke might be difficult to accommodate. The 1/rev amplitude of a radial absorber at 70% span (having significantly lower mass than the chordwise absorber and producing comparable lag damping) is of the order of 4% of the rotor blade span. The static displacement of the radial absorber under centrifugal load needs to be limited using a frequency-dependent (high static stiffness, low dynamic stiffness) or nonlinear spring. The chordwise absorber can also undergo a large static displacement under the chordwise component of the centrifugal load if there is an offset from the feather axis, and this would again have to be limited using a strategy such as a frequency-dependent spring. Significant advantages of the radial absorber are—higher lag damping, lower absorber mass, space for absorber mass travel, and no chordwise travel of blade center of gravity reducing susceptibility to aeroelastic instability and dynamic pitch-link loads.

  13. Porcelain enamel neutron absorbing material

    DOEpatents

    Iverson, Daniel C.

    1990-02-06

    A porcelain enamel composition as a neutron absorbing material can be prepared of a major proportion by weight of a cadmium compound and a minor proportion of compounds of boron, lithium and silicon. These compounds in the form of a porcelain enamel coating or layer on several alloys has been found to be particularly effective in enhancing the nuclear safety of equipment for use in the processing and storage of fissile material. The composition of the porcelain enamel coating can be tailored to match the coefficient of thermal expansion of the equipment to be coated and excellent coating adhesion can be achieved.

  14. Porcelain enamel neutron absorbing material

    DOEpatents

    Iverson, D.C.

    1987-11-20

    A porcelain enamel composition as a neutron absorbing material can be prepared of a major proportion by weight of a cadmium compound and a minor proportion of compound of boron, lithium and silicon. These compounds in the form of a porcelain enamel coating or layer on several alloys has been found to be particularly effective in enhancing the nuclear safety of equipment for use in the processing and storage of fissile material. The composition of the porcelain enamel coating can be tailored to match the coefficient of thermal expansion of the equipment to be coated and excellent coating adhesion can be achieved. 2 figs.

  15. Porcelain enamel neutron absorbing material

    DOEpatents

    Iverson, Daniel C.

    1990-01-01

    A porcelain enamel composition as a neutron absorbing material can be prepared of a major proportion by weight of a cadmium compound and a minor proportion of compounds of boron, lithium and silicon. These compounds in the form of a porcelain enamel coating or layer on several alloys has been found to be particularly effective in enhancing the nuclear safety of equipment for use in the processing and storage of fissile material. The composition of the porcelain enamel coating can be tailored to match the coefficient of thermal expansion of the equipment to be coated and excellent coating adhesion can be achieved.

  16. The Double Absorbing Boundary method

    NASA Astrophysics Data System (ADS)

    Hagstrom, Thomas; Givoli, Dan; Rabinovich, Daniel; Bielak, Jacobo

    2014-02-01

    A new approach is devised for solving wave problems in unbounded domains. It has common features to each of two types of existing techniques: local high-order Absorbing Boundary Conditions (ABC) and Perfectly Matched Layers (PML). However, it is different from both and enjoys relative advantages with respect to both. The new method, called the Double Absorbing Boundary (DAB) method, is based on truncating the unbounded domain to produce a finite computational domain Ω, and on applying a local high-order ABC on two parallel artificial boundaries, which are a small distance apart, and thus form a thin non-reflecting layer. Auxiliary variables are defined on the two boundaries and inside the layer bounded by them, and participate in the numerical scheme. The DAB method is first introduced in general terms, using the 2D scalar time-dependent wave equation as a model. Then it is applied to the 1D Klein-Gordon equation, using finite difference discretization in space and time, and to the 2D wave equation in a wave guide, using finite element discretization in space and dissipative time stepping. The computational aspects of the method are discussed, and numerical experiments demonstrate its performance.

  17. Multi-dimensional hydrodynamic simulations aimed at characterizing heavily aluminized RDX

    NASA Astrophysics Data System (ADS)

    Yoh, Jack J.; Kim, Bohoon; Kim, Minsung

    2015-06-01

    An accurate and reliable prediction of reactive flow is a challenging task for an energetic material subjected to an external shock impact. The present study aims at simulating the shock induced detonation of heavily aluminized RDX which contains 35% of aluminum. A series of gap tests with the longitudinal simulations involving gap substances are conducted to understand the inherent initiation process that depends on the shock propagation through multi-material domain and the high strain dynamics of nearby confinement materials. A pressure chamber test is used to validate the blast wave calculation of the sample charge, and a full 3-D hydrodynamic simulation is performed to predict fragmentation of an explosively loaded steel casing. The paper provides an elaborate description of how a heavily aluminized RDX is characterized in terms of its thermo-chemical response and multi-material interaction with inert confinement materials.

  18. Ductile Chromium in Heavily Cold-Drawn Cu75Cr25 Alloy

    NASA Astrophysics Data System (ADS)

    Chang, Yanli; Zhou, Zhiming; Guo, Ziqin; Wang, Yaping

    2016-01-01

    Microstructure evolution, gas content, and properties of the heavily cold-drawn Cu75Cr25 alloy were studied. Results showed that the oxygen and nitrogen contents of Cu75Cr25 alloy prepared by vacuum induction melting in calcia crucibles were low, about 320 and 20 ppm, respectively. The Cu75Cr25 material with low gas content can be cold drawn to lines with diameter less than 0.1 mm, in which Cr phase displays thin and curving morphology. The coherent interface, forming between Cu(111) and Cr(110) during the heavily cold-drawing process, constrained Cr phase and greatly improved its deformability as well as increased the strength of the Cu-Cr alloy. The breaking strength and electrical conductivity of the Cu75Cr25 alloy were about 577 MPa and 60 pct IACS, respectively.

  19. Bioavailability and toxicity of heavy metals in a heavily polluted river, in PRD, China.

    PubMed

    Li, Feng; Wen, Y-M; Zhu, P-T

    2008-07-01

    The research is designed to explore the SEM-AVS concept as a tool to assess bioavailability and toxicity of heavy metals in heavily polluted river sediments. The value of AVS and SEM is in a high level and only a few benthic invertebrate are found. Abundance of benthic invertebrate has significant correlation with SEM/AVS (r= -0.913, p<0.01) and SEM-AVS (r= -0.725, p<0.05). The analytical results of MDS (Non-matric Multi-dimensional Scaling) analysis indicate the benthic community structures of seven among nine stations where the SigmaSEM(5)-AVS<0 are similar. The two facts indicate the SEM-AVS concept also is useful to heavily polluted river sediments. PMID:18354814

  20. Isospin effects via Coulomb forces on the onset of multifragmentation in light and heavily charged systems

    NASA Astrophysics Data System (ADS)

    Sharma, Arun; Bharti, Arun

    2016-03-01

    We concurrently study the isospin effects via Coulomb forces and the nuclear equation of state and its momentum dependence on the onset of multifragmentation, i.e., critical energy point, in the light and heavily charged reactions of 40Ar + 45Sc and 84Kr + 197Au , respectively, using the isospin-dependent quantum molecular dynamics model. We find that Coulomb forces influence the onset of multifragmentation and result in the shift of the critical energy point towards lower and higher incident energies with and without their presence, respectively. Also, we observe that the critical energy point is sharper for the heavily charged system of 84Kr + 197Au when compared with the light charged system of 40Ar + 45Sc , where a small dip is observed and thus leads to the dependence of onset of multifragmentation, i.e., the critical energy point, on the reaction asymmetry as well as on the Coulomb forces.

  1. The use of bonded partial ceramic restorations to recover heavily compromised teeth.

    PubMed

    Politano, Gianfranco; Fabianelli, Andrea; Papacchini, Federica; Cerutti, Antonio

    2016-01-01

    Restorative procedures are accompanied by a reduction of tooth stability, a decrease of fracture resistance, and an increase in deflection of weakened cusps. The choice between a direct or an indirect restorative technique, mainly in posterior areas, is a challenge, and involves biomechanical, anatomical, functional, esthetic, and financial considerations. In this article, the pros and cons of direct restorations are examined, as well as an analysis of indirect restorations and an overview of dental ceramics. In particular, several clinical uses of lithium disilicate overlays with a circumferential adhesive ferrule effect are proposed: heavily compromised vital teeth with thin walls, cracked teeth, and endodontically treated molars. Clinical procedures are described step by step on the basis of data from scientific literature. In conclusion, the use of lithium disilicate in combination with adhesive technologies can lead to a more conservative, economic, and esthetic approach in the restoration of heavily compromised teeth. PMID:27433548

  2. Surface recombination velocity and diffusion length of minority carriers in heavily doped silicon layers

    NASA Technical Reports Server (NTRS)

    Gatos, H. C.; Watanabe, M.; Actor, G.

    1977-01-01

    Quantitative analysis of the electron beam-induced current and the dependence of the effective diffusion length of the minority carriers on the penetration depth of the electron beam were employed for the analysis of the carrier recombination characteristics in heavily doped silicon layers. The analysis is based on the concept of the effective excitation strength of the carriers which takes into consideration all possible recombination sources. Two dimensional mapping of the surface recombination velocity of P-diffused Si layers will be presented together with a three dimensional mapping of minority carrier lifetime in ion implanted Si. Layers heavily doped with As exhibit improved recombination characteristics as compared to those of the layers doped with P.

  3. Modeling the Absorbing Aerosol Index

    NASA Technical Reports Server (NTRS)

    Penner, Joyce; Zhang, Sophia

    2003-01-01

    We propose a scheme to model the absorbing aerosol index and improve the biomass carbon inventories by optimizing the difference between TOMS aerosol index (AI) and modeled AI with an inverse model. Two absorbing aerosol types are considered, including biomass carbon and mineral dust. A priori biomass carbon source was generated by Liousse et al [1996]. Mineral dust emission is parameterized according to surface wind and soil moisture using the method developed by Ginoux [2000]. In this initial study, the coupled CCM1 and GRANTOUR model was used to determine the aerosol spatial and temporal distribution. With modeled aerosol concentrations and optical properties, we calculate the radiance at the top of the atmosphere at 340 nm and 380 nm with a radiative transfer model. The contrast of radiance at these two wavelengths will be used to calculate AI. Then we compare the modeled AI with TOMS AI. This paper reports our initial modeling for AI and its comparison with TOMS Nimbus 7 AI. For our follow-on project we will model the global AI with aerosol spatial and temporal distribution recomputed from the IMPACT model and DAO GEOS-1 meteorology fields. Then we will build an inverse model, which applies a Bayesian inverse technique to optimize the agreement of between model and observational data. The inverse model will tune the biomass burning source strength to reduce the difference between modelled AI and TOMS AI. Further simulations with a posteriori biomass carbon sources from the inverse model will be carried out. Results will be compared to available observations such as surface concentration and aerosol optical depth.

  4. High-temperature ferromagnetism in heavily Fe-doped ferromagnetic semiconductor (Ga,Fe)Sb

    NASA Astrophysics Data System (ADS)

    Tu, Nguyen Thanh; Hai, Pham Nam; Anh, Le Duc; Tanaka, Masaaki

    2016-05-01

    We show high-temperature ferromagnetism in heavily Fe-doped ferromagnetic semiconductor (Ga1-x,Fex)Sb (x = 23% and 25%) thin films grown by low-temperature molecular beam epitaxy. Magnetic circular dichroism spectroscopy and anomalous Hall effect measurements indicate intrinsic ferromagnetism of these samples. The Curie temperature reaches 300 K and 340 K for x = 23% and 25%, respectively, which are the highest values reported so far in intrinsic III-V ferromagnetic semiconductors.

  5. Radio Constraints on Heavily Obscured Star Formation within Dark Gamma-Ray Burst Host Galaxies

    NASA Astrophysics Data System (ADS)

    Perley, D. A.; Perley, R. A.

    2013-12-01

    Highly dust-obscured starbursting galaxies (submillimeter galaxies and their ilk) represent the most extreme sites of star formation in the distant universe and contribute significantly to overall cosmic star formation beyond z > 1.5. Some stars formed in these environments may also explode as gamma-ray bursts (GRBs) and contribute to the population of "dark" bursts. Here we present Very Large Array wideband radio-continuum observations of 15 heavily dust-obscured Swift GRBs to search for radio synchrotron emission associated with intense star formation in their host galaxies. Most of these targets (11) are not detected. Of the remaining four objects, one detection is marginal, and for two others we cannot yet rule out the contribution of a long-lived radio afterglow. The final detection is secure, but indicates a star formation rate (SFR) roughly consistent with the dust-corrected UV-inferred value. Most galaxies hosting obscured GRBs are therefore not forming stars at extreme rates, and the amount of optical extinction seen along a GRB afterglow sightline does not clearly correlate with the likelihood that the host has a sufficiently high SFR to be radio-detectable. While some submillimeter galaxies do readily produce GRBs, these GRBs are often not heavily obscured—suggesting that the outer (modestly obscured) parts of these galaxies overproduce GRBs and the inner (heavily obscured) parts underproduce GRBs relative to their respective contributions to star formation, hinting at strong chemical or initial mass function gradients within these systems.

  6. Radio constraints on heavily obscured star formation within dark gamma-ray burst host galaxies

    SciTech Connect

    Perley, D. A.; Perley, R. A.

    2013-12-01

    Highly dust-obscured starbursting galaxies (submillimeter galaxies and their ilk) represent the most extreme sites of star formation in the distant universe and contribute significantly to overall cosmic star formation beyond z > 1.5. Some stars formed in these environments may also explode as gamma-ray bursts (GRBs) and contribute to the population of 'dark' bursts. Here we present Very Large Array wideband radio-continuum observations of 15 heavily dust-obscured Swift GRBs to search for radio synchrotron emission associated with intense star formation in their host galaxies. Most of these targets (11) are not detected. Of the remaining four objects, one detection is marginal, and for two others we cannot yet rule out the contribution of a long-lived radio afterglow. The final detection is secure, but indicates a star formation rate (SFR) roughly consistent with the dust-corrected UV-inferred value. Most galaxies hosting obscured GRBs are therefore not forming stars at extreme rates, and the amount of optical extinction seen along a GRB afterglow sightline does not clearly correlate with the likelihood that the host has a sufficiently high SFR to be radio-detectable. While some submillimeter galaxies do readily produce GRBs, these GRBs are often not heavily obscured—suggesting that the outer (modestly obscured) parts of these galaxies overproduce GRBs and the inner (heavily obscured) parts underproduce GRBs relative to their respective contributions to star formation, hinting at strong chemical or initial mass function gradients within these systems.

  7. BEAM QUALITY CORRECTION FACTORS FOR KAP METERS FOR LIGHTLY AND HEAVILY FILTERED X-RAY BEAMS.

    PubMed

    Herrnsdorf, L; Petersson, H

    2016-06-01

    Kerma-area product (KAP) meters have a pronounced energy dependence when measuring air KAP for lightly filtered X-ray beams (RQR). Today, it is also common with more heavily filtered beams. In this work, the energy dependence for lightly as well as heavily filtered beams (RQC) was investigated for several KAP meter models. The relative energy dependence of the readings of an external and an internal KAP meter was determined relative to an ionisation chamber, which had been calibrated at the primary standards laboratory. As a complement to the measurements, the sensitivity of a KAP meter for various X-ray beam qualities was modelled using Monte Carlo simulations of photon transport and absorption. The result showed a variation in relative energy dependence of up to 30 % for KAP meters for RQC beam qualities compared with RQR qualities. A reduced sensitivity of KAP meters for heavily filtered beams in comparison with lightly filtered ones was found, and it is important that the beam-specific radiation quality correction factors are applied to correct the registered KAP values. PMID:26994096

  8. Debt relief and public health spending in heavily indebted poor countries.

    PubMed Central

    Gupta, Sanjeev; Clements, Benedict; Guin-Siu, Maria Teresa; Leruth, Luc

    2002-01-01

    The Heavily Indebted Poor Countries (HIPC) Initiative, which was launched in 1996, is the first comprehensive effort by the international community to reduce the external debt of the world's poorest countries. The Initiative will generate substantial savings relative to current and past public spending on health and education in these countries. Although there is ample scope for raising public health spending in heavily indebted poor countries, it may not be advisable to spend all the savings resulting from HIPC resources for this purpose. Any comprehensive strategy for tackling poverty should also focus on improving the efficiency of public health outlays and on reallocating funds to programmes that are most beneficial to the poor. In order to ensure that debt relief increases poverty-reducing spending and benefits the poor, all such spending, not just that financed by HIPC resources, should be tracked. This requires that countries improve all aspects of their public expenditure management. In the short run, heavily indebted poor countries can take some pragmatic tracking measures based on existing public expenditure management systems, but in the longer run they should adopt a more comprehensive approach so as to strengthen their budget formulation, execution, and reporting systems. PMID:11953794

  9. Magnetic field effects on microwave absorbing materials

    NASA Technical Reports Server (NTRS)

    Goldberg, Ira; Hollingsworth, Charles S.; Mckinney, Ted M.

    1991-01-01

    The objective of this program was to gather information to formulate a microwave absorber that can work in the presence of strong constant direct current (DC) magnetic fields. The program was conducted in four steps. The first step was to investigate the electrical and magnetic properties of magnetic and ferrite microwave absorbers in the presence of strong magnetic fields. This included both experimental measurements and a literature survey of properties that may be applicable to finding an appropriate absorbing material. The second step was to identify those material properties that will produce desirable absorptive properties in the presence of intense magnetic fields and determine the range of magnetic field in which the absorbers remain effective. The third step was to establish ferrite absorber designs that will produce low reflection and adequate absorption in the presence of intense inhomogeneous static magnetic fields. The fourth and final step was to prepare and test samples of such magnetic microwave absorbers if such designs seem practical.

  10. Advanced absorber assembly design for breeder reactors

    SciTech Connect

    Pitner, A.L.; Birney, K.R.

    1980-01-01

    An advanced absorber assembly design has been developed for breeder reactor control rod applications that provides for improved in-reactor performance, longer lifetimes, and reduced fabrication costs. The design comprises 19 vented pins arranged in a circular array inside of round duct tubes. The absorber material is boron carbide; cladding and duct components are constructed from the modified Type 316 stainless steel alloy. Analyses indicate that this design will scram 30 to 40% faster than the reference FFTF absorber assembly. The basic design characteristics of this advanced FFTF absorber assembly are applicable to large core breeder reactor design concepts.

  11. Absorbent product and articles made therefrom

    NASA Technical Reports Server (NTRS)

    Dawn, F. S.; Correale, J. V. (Inventor)

    1982-01-01

    A multilayer absorbent product for use in contact with the skin to absorb fluids is described. The product has a water pervious facing layer for contacting the skin, and a first fibrous wicking layer overlaying the water pervious layer. A first container section is defined by inner and outer layers of a water pervious wicking material in between a first absorbent mass and a second container section defined by inner and outer layers of a water pervious wicking material between what is disposed a second absorbent mass, and a liquid impermeable/gas permeable layer overlaying the second fibrous wicking layer.

  12. TPX/TFTR Neutral Beam energy absorbers

    SciTech Connect

    Dahlgren, F.; Wright, K.; Kamperschroer, J.; Grisham, L.; Lontai, L.; Peters, C.; VonHalle, A.

    1993-11-01

    The present beam energy absorbing surfaces on the TFTR Neutral Beams such as Ion Dumps, Calorimeters, beam defining apertures, and scrapers, are simple water cooled copper plates which wee designed to absorb (via their thermal inertia) the incident beam power for two seconds with a five minute coal down interval between pulses. These components are not capable of absorbing the anticipated beam power loading for 1000 second TPX pulses and will have to be replaced with an actively cooled design. While several actively cooled energy absorbing designs were considered,, the hypervapotron elements currently being used on the JET beamlines were chosen due to their lower cooling water demands and reliable performance on JET.

  13. Advanced Reflector and Absorber Materials (Fact Sheet)

    SciTech Connect

    Not Available

    2010-08-01

    Fact sheet describing NREL CSP Program capabilities in the area of advanced reflector and absorber materials: evaluating performance, determining degradation rates and lifetime, and developing new coatings.

  14. Device for absorbing mechanical shock

    DOEpatents

    Newlon, C.E.

    1979-08-29

    This invention is a comparatively inexpensive but efficient shock-absorbing device having special application to the protection of shipping and storage cylinders. In a typical application, two of the devices are strapped to a cylinder to serve as saddle-type supports for the cylinder during storage and to protect the cylinder in the event it is dropped during lifting or lowering operations. In its preferred form, the invention includes a hardwood plank whose grain runs in the longitudinal direction. The basal portion of the plank is of solid cross-section, whereas the upper face of the plank is cut away to form a concave surface fittable against the sidewall of a storage cylinder. The concave surface is divided into a series of segments by transversely extending, throughgoing relief slots. A layer of elastomeric material is positioned on the concave face, the elastomer being extrudable into slots when pressed against the segments by a preselected pressure characteristic of a high-energy impact. The compressive, tensile, and shear properties of the hardwood and the elastomer are utilized in combination to provide a surprisingly high energy-absorption capability.

  15. Device for absorbing mechanical shock

    DOEpatents

    Newlon, Charles E.

    1980-01-01

    This invention is a comparatively inexpensive but efficient shock-absorbing device having special application to the protection of shipping and storage cylinders. In a typical application, two of the devices are strapped to a cylinder to serve as saddle-type supports for the cylinder during storage and to protect the cylinder in the event it is dropped during lifting or lowering operations. In its preferred form, the invention includes a hardwood plank whose grain runs in the longitudinal direction. The basal portion of the plank is of solid cross-section, whereas the upper face of the plank is cut away to form a concave surface fittable against the sidewall of a storage cylinder. The concave surface is divided into a series of segments by transversely extending, throughgoing relief slots. A layer of elastomeric material is positioned on the concave face, the elastomer being extrudable into slots when pressed against the segments by a preselected pressure characteristic of a high-energy impact. The compressive, tensile, and shear properties of the hardwood and the elastomer are utilized in combination to provide a surprisingly high energy-absorption capability.

  16. Human factors of target detection tasks within heavily cluttered video scenes

    NASA Astrophysics Data System (ADS)

    Huber, Samuel; Wellig, Peter

    2015-10-01

    Background: Algorithms show difficulties in distinguishing weak signals of a target from a cluttered background, a task that humans tend to master relatively easily. We conducted two studies to identify how various degrees of clutter influence operator performance and search patterns in a visual target detection task. Methods: First, 8 male subjects had to look for specific female targets within a heavily cluttered public area. Subjects were supported by differing amounts of markings that helped them to identify females in general. We presented video clips and analyzed the search patterns. Second, 18 subject matter experts had to identify targets on a heavily frequented motorway intersection. We presented them with video material from a UAV (Unmanned Aerial Vehicle) surveillance mission. The video image was subdivided in three zones: The central zone (CZ), a circle area of 10°. The peripheral zone (PZ) corresponding to a 4:3 format and the hyper peripheral zone (HPZ) which represented the lateral region specific to the 16:9 format. We analyzed fixation densities and task performance. Results: We found an approximately U-shaped correlation between the number of markings in a video and the degree of structure in search patterns as well as performance. For the motorway surveillance task we found a difference in mean detection time for CZ vs. HPZ (p=0.01) and PZ vs. HPZ (p=0.003) but no difference for CZ vs. PZ (p=0.491). There were no differences in detection rate for the respective zones. We found the highest fixation density in CZ decreasing towards HPZ. Conclusion: We were able to demonstrate that markings could increase surveillance operator performance in a cluttered environment as long as their number is kept in an optimal range. When performing a search task within a heavily cluttered environment, humans tend to show rather erratic search patterns and spend more time watching central picture areas.

  17. Comments on liquid hydrogen absorbers for MICE

    SciTech Connect

    Green, Michael A.

    2003-02-01

    This report describes the heat transfer problems associatedwith a liquid hydrogen absorber for the MICE experiment. This reportdescribes a technique for modeling heat transfer from the outside world,to the abosrber case and in its vacuum vessel, to the hydrogen and theninto helium gas at 14 K. Also presented are the equation for freeconvection cooling of the liquid hydrogen in the absorber.

  18. Incommensurate superstructure in heavily doped fullerene layer on Bi/Si(111) surface

    NASA Astrophysics Data System (ADS)

    Gruznev, D. V.; Bondarenko, L. V.; Tupchaya, A. Y.; Matetskiy, A. V.; Zotov, A. V.; Saranin, A. A.

    2015-08-01

    Cs adsorption onto the C60-covered Si(111)-β- √{ 3 } × √{ 3 } -Bi reconstruction has been studied by means of scanning tunneling microscopy and photoelectron spectroscopy. Unexpected increase in apparent size of every second C60 molecule has been detected, hereupon the close packed molecular array almost doubles its periodicity. The change affects only the fullerenes that are in direct contact with the metal-induced reconstruction and takes no place already in the second layer. Photoelectron studies have revealed that this incommensurate "2 × 2" superstructure of a heavily doped C60 monolayer remains in an insulating state regardless of doping level.

  19. High-temperature thermoelectric performance of heavily doped PbSe

    SciTech Connect

    Parker, David S; Singh, David J

    2010-01-01

    We present a model calculation, employing first-principles calculations as well as empirical data, which suggests that properly hole-doped bulk PbSe may show a Seebeck coefficient as high as 230 $\\mu V/K$, in a temperature regime in which the lattice thermal conductivity is rather small. It may show therefore show a figure-of-merit ZT as high as 2 for temperatures of 1000 K. Heavily doped p-type PbSe may offer better thermoelectric performance than the sister material, optimized PbTe, for high-temperature applications such as power generation.

  20. [Absorbed doses in dental radiology].

    PubMed

    Bianchi, S D; Roccuzzo, M; Albrito, F; Ragona, R; Anglesio, S

    1996-01-01

    The growing use of dento-maxillo-facial radiographic examinations has been accompanied by the publication of a large number of studies on dosimetry. A thorough review of the literature is presented in this article. Most studies were carried out on tissue equivalent skull phantoms, while only a few were in vivo. The aim of the present study was to evaluate in vivo absorbed doses during Orthopantomography (OPT). Full Mouth Periapical Examination (FMPE) and Intraoral Tube Panoramic Radiography (ITPR). Measurements were made on 30 patients, reproducing clinical conditions, in 46 anatomical sites, with 24 intra- and 22 extra-oral thermoluminiscent dosimeters (TLDS). The highest doses were measured, in orthopantomography, at the right mandibular angle (1899 mu Gy) in FMPE on the right naso-labial fold (5640 mu Gy and in ITPR on the palatal surface of the left second upper molar (1936 mu Gy). Intraoral doses ranged from 21 mu Gy, in orthopantomography, to 4494 mu Gy in FMPE. Standard errors ranged from 142% in ITPR to 5% in orthopantomography. The highest rate of standard errors was found in FMPE and ITPR. The data collected in this trial are in agreement with others in major literature reports. Disagreements are probably due to different exam acquisition and data collections. Such differences, presented comparison in several sites, justify lower doses in FMPE and ITPR. Advantages and disadvantages of in vivo dosimetry of the maxillary region are discussed, the former being a close resemblance to clinical conditions of examination and the latter the impossibility of collecting values in depth of tissues. Finally, both ITPR and FMPE required lower doses than expected, and can be therefore reconsidered relative to their radiation risk. PMID:8966249

  1. Solar sustained plasma/absorber conceptual design

    NASA Technical Reports Server (NTRS)

    Rodgers, R. J.; Krascella, N. L.; Kendall, J. S.

    1979-01-01

    A space power system concept was evaluated which uses concentrated solar energy to heat a working fluid to temperatures as high as 4000 K. The high temperature working fluid could be used for efficient electric power production in advanced thermal or magnetohydrodynamic conversion cycles. Energy absorber configurations utilizing particles or cesium vapor absorber material were investigaed. Results of detailed radiant heat transfer calculations indicated approximately 86 percent of the incident solar energy could be absorbed within a 12-cm-dia flowing stream of gas borne carbon particles. Calculated total energy absorption in the cesium vapor seeded absorber configuration ranged from 34 percent to 64 percent of the incident solar energy. Solar flux concentration ratios of between approximately 3000 and 10,000 will be required to sustain absorber temperatures in the range from 3000 K to 4000 K.

  2. Gold absorbing film for a composite bolometer

    NASA Technical Reports Server (NTRS)

    Dragovan, M.; Moseley, S. H.

    1984-01-01

    The principles governing the design of metal films are reviewed, with attention also given to the choice of metals. A description is then given of the characteristics of a bolometer with a gold absorbing film. It is demonstrated that gold is effective as an absorbing film for a millimeter bolometer operated at 1.5 K. At 1.5 K, gold is significantly better than bismuth since gold has a lower heat capacity for the absorbing film. At 0.3 K, gold and bismuth are both suitable. It is pointed out that at temperatures below 0.3 K, a superconducting absorbing film can have a heat capacity low enough not to dominate the heat capacity of the detector; for this reason, it may give better performance than a nonsuperconducting absorbing film.

  3. Structured Metal Film as Perfect Absorber

    NASA Astrophysics Data System (ADS)

    Xiong, Xiang; Jiang, Shang-Chi; Peng, Ru-Wen; Wang, Mu

    2014-03-01

    With standing U-shaped resonators, fish-spear-like resonator has been designed for the first time as the building block to assemble perfect absorbers. The samples have been fabricated with two-photon polymerization process and FTIR measurement results support the effectiveness of the perfect absorber design. In such a structure the polarization-dependent resonance occurs between the tines of the spears instead of the conventional design where the resonance occurs between the metallic layers separated by a dielectric interlayer. The incident light neither transmits nor reflects back which results in unit absorbance. The power of light is trapped between the tines of spears and finally be absorbed. The whole structure is covered with a continuous metallic layer with good thermo-conductance, which provides an excellent approach to deal with heat dissipation, is enlightening in exploring metamaterial absorbers.

  4. Recrystallization Behavior of a Heavily Deformed Austenitic Stainless Steel During Iterative Type Annealing

    NASA Astrophysics Data System (ADS)

    Ravi Kumar, B.; Sharma, Sailaja

    2014-09-01

    The study describes evolution of the recrystallization microstructure in an austenitic stainless steel during iterative or repetitive type annealing process. The starting heavily cold deformed microstructure consisted of a dual phase structure i.e., strain-induced martensite (SIM) (43 pct in volume) and heavily deformed large grained retained austenite. Recrystallization behavior was compared with Johnson Mehl Avrami and Kolmogorov model. Early annealing iterations led to reversion of SIM to reversed austenite. The microstructure changes observed in the retained austenite and in the reverted austenite were mapped by electron backscatter diffraction technique and transmission electron microscope. The reversed austenite was characterized by a fine polygonal substructure consisting of low-angle grain boundaries. With an increasing number of annealing repetitions, these boundaries were gradually replaced by high-angle grain boundaries and recrystallized into ultrafine-grained microstructure. On the other hand, recrystallization of retained austenite grains was sluggish in nature. Progress of recrystallization in these grains was found to take place by a gradual evolution of subgrains and their subsequent transformation into fine grains. The observed recrystallization characteristics suggest continuous recrystallization type process. The analysis provided basic insight into the recrystallization mechanisms that enable the processing of ultrafine-grained fcc steels by iterative type annealing. Tensile properties of the processed material showed a good combination of strength and ductility.

  5. Recrystallization Behavior of a Heavily Deformed Austenitic Stainless Steel During Iterative Type Annealing

    NASA Astrophysics Data System (ADS)

    Ravi Kumar, B.; Sharma, Sailaja

    2014-12-01

    The study describes evolution of the recrystallization microstructure in an austenitic stainless steel during iterative or repetitive type annealing process. The starting heavily cold deformed microstructure consisted of a dual phase structure i.e., strain-induced martensite (SIM) (43 pct in volume) and heavily deformed large grained retained austenite. Recrystallization behavior was compared with Johnson Mehl Avrami and Kolmogorov model. Early annealing iterations led to reversion of SIM to reversed austenite. The microstructure changes observed in the retained austenite and in the reverted austenite were mapped by electron backscatter diffraction technique and transmission electron microscope. The reversed austenite was characterized by a fine polygonal substructure consisting of low-angle grain boundaries. With an increasing number of annealing repetitions, these boundaries were gradually replaced by high-angle grain boundaries and recrystallized into ultrafine-grained microstructure. On the other hand, recrystallization of retained austenite grains was sluggish in nature. Progress of recrystallization in these grains was found to take place by a gradual evolution of subgrains and their subsequent transformation into fine grains. The observed recrystallization characteristics suggest continuous recrystallization type process. The analysis provided basic insight into the recrystallization mechanisms that enable the processing of ultrafine-grained fcc steels by iterative type annealing. Tensile properties of the processed material showed a good combination of strength and ductility.

  6. ISAR image analysis and recovery with unavailable or heavily corrupted data

    NASA Astrophysics Data System (ADS)

    Stankovic, Ljubisa

    2015-07-01

    Common ISAR radar images and signals can be reconstructed from much fewer samples than the sampling theorem requires since they are usually sparse. Unavailable randomly positioned samples can result from heavily corrupted parts of the signal. Since these samples can be omitted and declared as unavailable, the application of the compressive sensing methods in the recovery of heavily corrupted signal and radar images is possible. A\\ simple direct method for the recovery of unavailable signal samples and the calculation of the restored ISAR image is reviewed. An analysis of the noise influence is performed. For fast maneuvering ISAR targets the sparsity property is lost since the ISAR image is blurred. A nonparametric quadratic time-frequency representations based method is used to restore the ISAR image sparsity. However, the linear relation between the signal and the sparsity domain transformation is lost. A recently proposed gradient recovery algorithm is adapted for this kind of analysis. It does not require the linear relation of the signal and its sparsity domain transformation in the process of unavailable data recovery. The presented methods and results are tested on several numerical examples proving the expected accuracy and improvements.

  7. Docetaxel Rechallenge in a Heavily Pretreated Patient With Castration-Resistant Prostate Cancer

    PubMed Central

    Di Lorenzo, Giuseppe; Pagliuca, Martina; Perillo, Teresa; Benincasa, Alfonso; Bosso, Davide; De Placido, Sabino; Buonerba, Carlo

    2016-01-01

    Abstract Chemotherapy agents for patients with metastatic castration-resistant prostate cancer (mCRPC) include docetaxel and cabazitaxel. Although docetaxel is approved in the first-line treatment setting, a few studies have shown that selected patients can benefit from docetaxel rechallenge. We, here, report the case of a heavily pretreated mCRPC patient who reported clinical benefit from receiving docetaxel after previous exposure to docetaxel, cabazitaxel, abiraterone, and enzalutamide. After 4 cycles of treatment, patient's performance status had improved to 1, the hemoglobin level was 12.9 g/dL and his serum prostate specific antigen levels were reduced by >70%, with no treatment-related adverse events. Although docetaxel rechallenge is a therapeutic option for selected patients, the risk of cumulative toxicity described in literature must be carefully considered. As the risk of cabazitaxel-related cumulative toxicity is probably lower, retreatment with cabazitaxel rather than docetaxel may also be an option in the setting of heavily pretreated mCRPC patients. PMID:27057826

  8. Therapeutic effect of rotational atherectomy with implantation of drug eluting stent in heavily coronary calcified patients

    PubMed Central

    Wei, Zhong-Hai; Xie, Jun; Wang, Lian; Huang, Wei; Wang, Kun; Kang, Li-Na; Zhang, Jing-Mei; Song, Jie; Xu, Biao

    2016-01-01

    Background Rotational atherectomy (RA) could facilitate the percutaneous coronary intervention (PCI) in heavily coronary calcified patients. The effectiveness and safety of this technique needs to be further evaluated. Methods & Results Eighty patients who underwent RA in our center from September 2011 to June 2014 were enrolled. The mean age was 72.4 ± 10.4 years. The left ventricular ejection fraction (LVEF) was average 52.3% ± 8.48% and the estimated glomerular filtration rate was 73.2 ± 3.20 mL/min per 1.73 m2. The coronary lesions were complex, with Syntax score 29.5 ± 9.86. The diameter of reference vessel was 3.4 ± 0.45 mm and the average diameter stenosis of target vessels was 80% ± 10%. All the patients were deployed with drug eluting stents (DES) successfully after RA. The patients were followed up for 12–18 months. Kaplan-Meier plots estimated the survival rate was 93.4% and the cumulative incidence of major adverse cardiac and cerebral events (MACCE) was 25.4%. Bleeding and procedural-related complications were quite low. COX proportional hazards model for multivariate analysis demonstrated that diabetes, LVEF and maximum pressure of postdilatation were the predictors of MACCE. Conclusions RA followed by implantation of DES was effective and safe for heavily coronary calcified patients. Diabetes, LVEF and maximum pressure of postdilatation were predictive for MACCE. PMID:27103918

  9. Avalanche Effect in Si Heavily Irradiated Detectors: Physical Model and Perspectives for Application

    SciTech Connect

    Eremin V.; Li Z.; Verbitskaya, E.; Zabrodskii, A.; Harkonen, J.

    2011-05-07

    The model explaining an enhanced collected charge in detectors irradiated to 10{sup 15}-10{sup 16} n{sub eq}/cm{sup 2} is developed. This effect was first revealed in heavily irradiated n-on-p detectors operated at high bias voltage ranging from 900 to 1700 V. The model is based on the fundamental effect of carrier avalanche multiplication in the space charge region and in our case is extended with a consideration of p-n junctions with a high concentration of the deep levels. It is shown that the efficient trapping of free carriers from the bulk generation current to the deep levels of radiation induced defects leads to the stabilization of the irradiated detector operation in avalanche multiplication mode due to the reduction of the electric field at the junction. The charge collection efficiency and the detector reverse current dependences on the applied bias have been numerically simulated in this study and they well correlate to the recent experimental results of CERN RD50 collaboration. The developed model of enhanced collected charge predicts a controllable operation of heavily irradiated detectors that is promising for the detector application in the upcoming experiments in a high luminosity collider.

  10. Spatial distribution and source identification of trace elements in topsoil from heavily industrialized region, Aliaga, Turkey.

    PubMed

    Kara, Melik; Dumanoğlu, Yetkin; Altıok, Hasan; Elbir, Tolga; Odabası, Mustafa; Bayram, Abdurrahman

    2014-10-01

    Topsoil samples (n = 40) were collected from a heavily industrialized region in Turkey. The region includes several scrap processing iron-steel plants with electric arc furnaces (EAFs), a petroleum refinery, a petrochemical complex, steel rolling mills, a natural gas-fired power plant, ship-breaking yards and very dense transportation activities. The region has undergone a rapid transition from an agricultural region to a heavily industrialized region in the last three decades. Collected soil samples were analyzed for 48 trace elements using inductively coupled plasma-mass spectrometry (ICP-MS). The elemental distribution pattern in the region indicated that Nemrut area with dense iron-steel production activities was a hotspot for elemental pollution. In addition to crustal elements, concentrations of anthropogenic trace elements (i.e., Fe, Zn, Pb, Mn, Cu, Cd, Cr and Mo) were very high in the area influencing many parts of the region. Elemental compositions of fugitive sources polluting the soil (i.e., paved and unpaved roads, slag piles, EAFs filter dust piles and coal piles) were also determined. The methods (enrichment factors [EFs] and the index of geoaccumulation [Igeo]) used for determination of pollution status of soil showed that Cr, Ag, Zn, As and Pb were the strongly contaminating elements for the region. Principal component analysis (PCA) clearly indicated that anthropogenic sources (steel production, refinery and petrochemical processes and traffic) were important sources in this region. PMID:24859861

  11. Denuded Zone Formation in Germanium Codoped Heavily Phosphorus-Doped Czochralski Silicon

    NASA Astrophysics Data System (ADS)

    Lin, Li-Xia; Chen, Jia-He; Wu, Peng; Zeng, Yu-Heng; Ma, Xiang-Yang; Yang, De-Ren

    2011-03-01

    The formation of a denuded zone (DZ) by conventional furnace annealing (CFA) and rapid thermal annealing (RTA) based denudation processing is investigated and the gettering of copper (Cu) atoms in germanium co-doped heavily phosphorus-doped Czochralski (GHPCZ) silicon wafers is evaluated. It is suggested that both a good quality defect-free DZ with a suitable width in the sub-surface area and a high density bulk micro-defect (BMD) region could be formed in heavily phosphorus-doped Czochralski (HPCZ) silicon and GHPCZ silicon wafers. This is ascribed to the formation of phosphorus-vacancy (P-V) related complexes and germanium-vacancy (GeV) related complexes. Compared with HPCZ silicon, the DZ width is wider in the GHPCZ silicon sample with CFA-based denudation processing but narrower in the one with two-step RTA pretreatments. These phenomena are ascribed to the enhancing effect of germanium on oxygen out-diffusion movement and oxygen precipitate nucleation, respectively. Furthermore, fairly clean DZs near the surface remain in both the HPCZ and GHPCZ silicon wafers after Cu in-diffusion, except for the HPCZ silicon wafer which underwent denudation processing with a CFA pretreatment, suggesting that germanium doping could improve the gettering of Cu contamination.

  12. Marine Reserves and Reproductive Biomass: A Case Study of a Heavily Targeted Reef Fish

    PubMed Central

    Taylor, Brett M.; McIlwain, Jennifer L.; Kerr, Alexander M.

    2012-01-01

    Recruitment overfishing (the reduction of a spawning stock past a point at which the stock can no longer replenish itself) is a common problem which can lead to a rapid and irreversible fishery collapse. Averting this disaster requires maintaining a sufficient spawning population to buffer stochastic fluctuations in recruitment of heavily harvested stocks. Optimal strategies for managing spawner biomass are well developed for temperate systems, yet remain uncertain for tropical fisheries, where the danger of collapse from recruitment overfishing looms largest. In this study, we explored empirically and through modeling, the role of marine reserves in maximizing spawner biomass of a heavily exploited reef fish, Lethrinus harak around Guam, Micronesia. On average, spawner biomass was 16 times higher inside the reserves compared with adjacent fished sites. Adult density and habitat-specific mean fish size were also significantly greater. We used these data in an age-structured population model to explore the effect of several management scenarios on L. harak demography. Under minimum-size limits, unlimited extraction and all rotational-closure scenarios, the model predicts that preferential mortality of larger and older fish prompt dramatic declines in spawner biomass and the proportion of male fish, as well as considerable declines in total abundance. For rotational closures this occurred because of the mismatch between the scales of recovery and extraction. Our results highlight how alternative management scenarios fall short in comparison to marine reserves in preserving reproductively viable fish populations on coral reefs. PMID:22761836

  13. Thin film absorber for a solar collector

    DOEpatents

    Wilhelm, William G.

    1985-01-01

    This invention pertains to energy absorbers for solar collectors, and more particularly to high performance thin film absorbers. The solar collectors comprising the absorber of this invention overcome several problems seen in current systems, such as excessive hardware, high cost and unreliability. In the preferred form, the apparatus features a substantially rigid planar frame with a thin film window bonded to one planar side of the frame. An absorber in accordance with the present invention is comprised of two thin film layers that are sealed perimetrically. In a preferred embodiment, thin film layers are formed from a metal/plastic laminate. The layers define a fluid-tight planar envelope of large surface area to volume through which a heat transfer fluid flows. The absorber is bonded to the other planar side of the frame. The thin film construction of the absorber assures substantially full envelope wetting and thus good efficiency. The window and absorber films stress the frame adding to the overall strength of the collector.

  14. Neutron absorbing coating for nuclear criticality control

    DOEpatents

    Mizia, Ronald E.; Wright, Richard N.; Swank, William D.; Lister, Tedd E.; Pinhero, Patrick J.

    2007-10-23

    A neutron absorbing coating for use on a substrate, and which provides nuclear criticality control is described and which includes a nickel, chromium, molybdenum, and gadolinium alloy having less than about 5% boron, by weight.

  15. Design of a magnetorheological automotive shock absorber

    NASA Astrophysics Data System (ADS)

    Lindler, Jason E.; Dimock, Glen A.; Wereley, Norman M.

    2000-06-01

    Double adjustable shock absorbers allow for independent adjustment of the yield force and post-yield damping in the force versus velocity response. To emulate the performance of a conventional double adjustable shock absorber, a magnetorheological (MR) automotive shock absorber was designed and fabricated at the University of Maryland. Located in the piston head, an applied magnetic field between the core and flux return increases the force required for a given piston rod velocity. Between the core and flux return, two different shaped gaps meet the controllable performance requirements of a double adjustable shock. A uniform gap between the core and the flux return primarily adjusts the yield force of the shock absorber, while a non-uniform gap allows for control of the post-yield damping. Force measurements from sinusoidal displacement cycles, recorded on a mechanical damper dynamometer, validate the performance of uniform and non- uniform gaps for adjustment of the yield force and post-yield damping, respectively.

  16. Durability of Polymeric Glazing and Absorber Materials

    SciTech Connect

    Jorgensen, G.; Terwilliger, K.; Bingham, C.; Milbourne, M.

    2005-01-01

    The Solar Heating and Lighting Program has set the goal of reducing the cost of solar water heating systems by at least 50%. An attractive approach to such large cost reduction is to replace glass and metal parts with less-expensive, lighter-weight, more-integrated polymeric components. The key challenge with polymers is to maintain performance and assure requisite durability for extended lifetimes. The objective of this task is to quantify lifetimes through measurement of the optical and mechanical stability of candidate polymeric glazing and absorber materials. Polycarbonate sheet glazings, as proposed by two industry partners, have been tested for resistance to UV radiation with three complementary methods. Incorporation of a specific 2-mil thick UV-absorbing screening layer results in glazing lifetimes of at least 15 years; improved screens promise even longer lifetimes. Proposed absorber materials were tested for creep and embrittlement under high temperature, and appear adequate for planned ICS absorbers.

  17. Mucool Hydrogen Absorber R and D

    SciTech Connect

    Cummings, Mary Anne

    2006-03-20

    The Mucool hydrogen absorber program will be presented. An update of current projects will be described, and the next year's plan will be reviewed, along with efforts in collaboration with the Muon International Cooling Experiment.

  18. Passive Earth Entry Vehicle Energy Absorbing Systems

    NASA Astrophysics Data System (ADS)

    Kellas, S.; Maddock, R. W.

    2014-06-01

    A critical element of a passive EEV performance is the energy absorbing system required to attenuate the dynamic landing loads. Two design approaches are described and the pros and cons based on particular mission requirements are discussed.

  19. Attenuation of external Bremsstrahlung in metallic absorbers

    SciTech Connect

    Dhaliwal, A.S.; Powar, M.S.; Singh, M. )

    1990-12-01

    In this paper attenuation of bremsstrahlung from {sup 147}Pm and {sup 170}Tm beta emitters has been studied in aluminum, copper, tin, and lead metallic absorbers. Bremsstrahlung spectra and mass attenuation coefficients for monoenergetic gamma rays are used to calculate theoretical attenuation curves. Magnetic deflection and beta stopping techniques are used to measure the integral bremsstrahlung intensities above 30 keV in different target thicknesses. Comparison of measured and calculated attenuation curves shows a good agreement for various absorbers, thus providing a test of this technique, which may be useful in understanding bremsstrahlung intensity buildup and in the design of optimum shielding for bremsstrahlung sources. It is found that the absorption of bremsstrahlung in metallic absorbers does not obey an exponential law and that absorbers act as energy filters.

  20. Perfectly matched layer based multilayer absorbers

    NASA Astrophysics Data System (ADS)

    Stefaniuk, Tomasz; Stolarek, Marcin; Pastuszczak, Anna; Wróbel, Piotr; Wieciech, Bartosz; Antosiewicz, Tomasz J.; Kotyński, Rafał

    2015-05-01

    Broadband layered absorbers are analysed theoretically and experimentally. A genetic algorithm is used to opti- mize broadband and wide-angle of incidence metal-dielectric layered absorbers. An approximate representation of the perfectly matched layer with a spatially varied absorption strength is discussed. The PML is realised as a stack of uniform and isotropic metamaterial layers with permittivieties and permeabilities given from the effective medium theory. This approximate representation of PML is based on the effective medium theory and we call it an effective medium PML (EM-PML).1 We compare the re ection properties of the layered absorbers to that of a PML material and demonstrate that after neglecting gain and magnetic properties, the absorber remains functional.

  1. Optically detected cyclotron resonance in heavily boron-doped silicon nanostructures on n-Si (100)

    SciTech Connect

    Bagraev, N. T. Kuzmin, R. V.; Gurin, A. S.; Klyachkin, L. E.; Malyarenko, A. M.; Mashkov, V. A.

    2014-12-15

    Electron and hole cyclotron resonance at a frequency of 94 GHz is detected by a change in the intensity of photoluminescence lines whose positions are identical to those of dislocation luminescence lines D1 and D2 in single-crystal silicon and in heavily boron-doped silicon nanostructures on the Si (100) surface. The angular dependence of the spectrum of the optically detected cyclotron resonance corresponds to the tensor of the electron and hole effective mass in single-crystal silicon, and the resonance-line width indicates long carrier free-path times close to 100 ps. The results obtained are discussed within the framework of the interrelation of the electron-vibration coupling to charge and spin correlations in quasi-one-dimensional chains of dangling bonds in silicon.

  2. Microtexture of constituent phases in a heavily warm- rolled and annealed duplex stainless steel

    NASA Astrophysics Data System (ADS)

    Zaid, M.; Bhattacharjee, P. P.

    2015-04-01

    Evolution of microtexture during isothermal annealing of a heavily warm-rolled Fe- 0.08%C-24.18%Cr-10.5%Ni duplex stainless steel (DSS) having approximately equal volume fraction of ferrite and austenite was investigated in the present work. The DSS was warm-rolled to ∼90% reduction in thickness at three different temperatures, namely, 225°C, 425°C and 625°C followed by isothermal annealing at 1175°C for different length of time. Austenite showed pure metal or copper type texture at different warm-rolling temperatures. In contrast, the texture of ferrite in different warm-rolled DSS revealed the presence of RD (RD//<110>) and ND (ND//<111>) fibers. The annealing texture of austenite showed retention of the deformation texture components while ferrite revealed strong RD-fiber.

  3. Facilitating political decisions using species distribution models to assess restoration measures in heavily modified estuaries.

    PubMed

    Heuner, Maike; Weber, Arnd; Schröder, Uwe; Kleinschmit, Birgit; Schröder, Boris

    2016-09-15

    The European Water Framework Directive requires a good ecological potential for heavily modified water bodies. This standard has not been reached for most large estuaries by 2015. Management plans for estuaries fall short in linking implementations between restoration measures and underlying spatial analyses. The distribution of emergent macrophytes - as an indicator of habitat quality - is here used to assess the ecological potential. Emergent macrophytes are capable of settling on gentle tidal flats where hydrodynamic stress is comparatively low. Analyzing their habitats based on spatial data, we set up species distribution models with 'elevation relative to mean high water', 'mean bank slope', and 'length of bottom friction' from shallow water up to the vegetation belt as key predictors representing hydrodynamic stress. Effects of restoration scenarios on habitats were assessed applying these models. Our findings endorse species distribution models as crucial spatial planning tools for implementing restoration measures in modified estuaries. PMID:27339739

  4. Characterization of heavily B-doped polycrystalline diamond films using Raman spectroscopy and electron spin resonance

    NASA Astrophysics Data System (ADS)

    Gonon, P.; Gheeraert, E.; Deneuville, A.; Fontaine, F.; Abello, L.; Lucazeau, G.

    1995-12-01

    Heavily B-doped polycrystalline diamond films ([B]≳1019 cm-3) are studied by Raman spectroscopy and electron spin resonance. The formation of an impurity band is accompanied by a Fano-type interference for the one-phonon scattering. Bands at 1200 and 500 cm-1 are observed in Raman spectroscopy for concentrations above 1020 cm-3. They are related to maxima in the phonon density of states, and are ascribed to disordered regions or crystalline regions of very small size. The concentration of defects associated with the paramagnetic signal observed around g=2.0030 increases drastically above 1021 B cm-3. The Mott insulator-metal transition is accompanied by the presence of a new paramagnetic signal (g=2.0007 for 2×1020 B cm-3, g=1.9990 for 1021 B cm-3) ascribed to free holes in the impurity band.

  5. Differential diagnosis of heavily pigmented melanocytic lesions: challenges and diagnostic approach.

    PubMed

    Aung, Phyu P; Mutyambizi, Kudakwashe K; Danialan, Richard; Ivan, Doina; Prieto, Victor G

    2015-12-01

    The differential diagnosis of heavily pigmented melanocytic neoplasms includes melanoma (especially animal type), melanosis of partially or completely regressed melanoma, blue naevus (BN), pigmented Spitzoid lesions, recurrent naevus, combined naevus, pigmented spindle cell naevus, epithelioid blue naevus of the Carney complex/pigmented epithelioid melanocytoma, deep penetrating naevus, hyperpigmented scar after surgery of melanoma in which there are also melanophages and hyperpigmentation due to the minocycline, a tattoo or a hyperpigmented scar. Pathologists face challenges when evaluating a pigmented lesion, especially in a small superficial biopsy, because it is difficult to access important histopathological features to differentiate benign versus malignant melanocytic lesions. The histological features that favour a diagnosis of melanoma include dimension (>6 mm), asymmetry, poor circumscription, irregular confluent nests, confluent lentiginous junctional melanocytic proliferation, lack of maturation with descent in the dermis, suprabasal pagetoid melanocytes, asymmetrical distribution of melanin pigment, cytological atypia, dermal mitotic figures, asymmetrical dermal lymphocytic infiltrate and necrosis. PMID:26602414

  6. Fluvial valleys in the heavily cratered terrains of Mars: Evidence for paleoclimatic change?

    NASA Technical Reports Server (NTRS)

    Gulick, V. C.; Baker, V. R.

    1993-01-01

    Whether the formation of the Martian valley networks provides unequivocal evidence for drastically different climatic conditions remains debatable. Recent theoretical climate modeling precludes the existence of a temperate climate early in Mars' geological history. An alternative hypothesis suggests that Mars had a globally higher heat flow early in its geological history, bringing water tables to within 350 m of the surface. While a globally higher heat flow would initiate ground water circulation at depth, the valley networks probably required water tables to be even closer to the surface. Additionally, it was previously reported that the clustered distribution of the valley networks within terrain types, particularly in the heavily cratered highlands, suggests regional hydrological processes were important. The case for localized hydrothermal systems is summarized and estimates of both erosion volumes and of the implied water volumes for several Martian valley systems are presented.

  7. Study of anomalous charge collection efficiency in heavily irradiated silicon strip detectors

    NASA Astrophysics Data System (ADS)

    Mikuž, M.; Cindro, V.; Kramberger, G.; Mandić, I.; Zavrtanik, M.

    2011-04-01

    Anomalous charge collection efficiency observed in heavily irradiated silicon strip detectors operated at high bias voltages has been studied in terms of a simple model and experimentally using 25 ns shaping electronics and transient current technique (TCT) with edge-on laser injection. The model confirmed qualitatively the explanation by electron impact ionization in the high electric field close to the strips, but failed in the quantitative description of the collected charge. First results on a Hamamatsu strip detector irradiated to 5×1015 neq/cm2 and operated at bias voltages in excess of 1000 V exhibit charge collection similar to what obtained on Micron devices. TCT tests with local charge injection by a laser confirm the validity of a linear extrapolation of trapping to very high fluences and reveal significant charge collection from the non-depleted volume of the detector.

  8. Cascade window-based procedure for impulse noise removal in heavily corrupted images

    NASA Astrophysics Data System (ADS)

    Awad, Ali S.; Man, Hong; Khashanah, Khaldoun

    2010-01-01

    A cascade of filtering windows is implemented iteratively for removing random-valued impulse noise in heavily corrupted images. This method is based on the peer group concept (PGC), so a pixel is considered as noise-free if and only if for each window size, there exists a peer group of certain threshold cardinality for it. Otherwise, the pixel is considered as noisy. In the restoration process, the corrupted pixels are restored by taking the mean value of the remaining good pixels in the filtering window. Extensive simulations demonstrate that the proposed method produces competitive results at low noise rates, but at high noise rates, it outperforms other state-of-the-art methods. This approach efficiently suppresses the impulse noise, shows a low computational complexity, and has an equal effect on both color and gray-level images.

  9. Multilayer Radar Absorbing Non-Woven Material

    NASA Astrophysics Data System (ADS)

    Dedov, A. V.; Nazarov, V. G.

    2016-06-01

    We study the electrical properties of multilayer radar absorbing materials obtained by adding nonwoven sheets of dielectric fibers with an intermediate layer of electrically conductive carbon fibers. Multilayer materials that absorb electromagnetic radiation in a wide frequency range are obtained by varying the content of the carbon fibers. The carbon-fiber content dependent mechanism of absorption of electromagnetic radiation by sheets and multilayer materials is considered.

  10. Porous absorber for solar air heaters

    SciTech Connect

    Finch, J.A.

    1980-09-10

    A general discussion of the factors affecting solar collector performance is presented. Bench scale tests done to try to determine the heat transfer characteristics of various screen materials are explained. The design, performance, and evaluation of a crude collector with a simple screen stack absorber is treated. The more sophisticated absorber concept, and its first experimental approximation is examined. A short summary of future plans for the collector concept is included. (MHR)

  11. Heavily obscured quasar host galaxies at z ∼ 2 are discs, not major mergers

    NASA Astrophysics Data System (ADS)

    Schawinski, Kevin; Simmons, Brooke D.; Urry, C. Megan; Treister, Ezequiel; Glikman, Eilat

    2012-09-01

    We explore the nature of heavily obscured quasar host galaxies at z˜ 2 using deep Hubble Space Telescope Wide Field Camera 3/infrared imaging of 28 dust-obscured galaxies (DOGs) to investigate the role of major mergers in driving black hole growth. The high levels of obscuration of the quasars selected for this study act as a natural coronagraph, blocking the quasar light and allowing a clear view of the underlying host galaxy. The sample of heavily obscured quasars represents a significant fraction of the cosmic mass accretion on supermassive black holes as the quasars have inferred bolometric luminosities around the break of the quasar luminosity function. We find that only a small fraction (4 per cent, at most 11-25 per cent) of the quasar host galaxies are major mergers. Fits to their surface brightness profiles indicate that 90 per cent of the host galaxies are either disc dominated, or have a significant disc. This disc-like host morphology, and the corresponding weakness of bulges, is evidence against major mergers and suggests that secular processes are the predominant driver of massive black hole growth. Finally, we suggest that the coincidence of mergers and active galactic nucleus activity is luminosity dependent, with only the most luminous quasars being triggered mostly by major mergers. a MUSYC catalogue ID, see Cardamone et al. (2010). Objects with X-ray detections are marked with *. b See images shown in Fig. 1. c The ratio of the host luminosity to the point source luminosity, reported only when GALFIT requires an unresolved object to yield a physical fit. This may be due to an AGN point source (in the case of the X-ray-detected DOGs) or an unresolved bulge or central concentration, i.e. a central bulge. d See Fig. 2.

  12. Tunability of the dielectric function of heavily doped germanium thin films for mid-infrared plasmonics

    NASA Astrophysics Data System (ADS)

    Frigerio, Jacopo; Ballabio, Andrea; Isella, Giovanni; Sakat, Emilie; Pellegrini, Giovanni; Biagioni, Paolo; Bollani, Monica; Napolitani, Enrico; Manganelli, Costanza; Virgilio, Michele; Grupp, Alexander; Fischer, Marco P.; Brida, Daniele; Gallacher, Kevin; Paul, Douglas J.; Baldassarre, Leonetta; Calvani, Paolo; Giliberti, Valeria; Nucara, Alessandro; Ortolani, Michele

    2016-08-01

    Heavily doped semiconductor thin films are very promising for application in mid-infrared plasmonic devices because the real part of their dielectric function is negative and broadly tunable in the 5 to 50 μ m wavelength range at least. In this work, we investigate the electrodynamics of heavily n -type-doped germanium epilayers at infrared frequencies beyond the assumptions of the Drude model. The films are grown on silicon and germanium substrates, are in situ doped with phosphorous in the 1017 to 1019 cm-3 range, then screened plasma frequencies in the 100 to 1200 cm-1 range were observed. We employ infrared spectroscopy, pump-probe spectroscopy, and dc transport measurements to determine the tunability of the plasma frequency. Although no plasmonic structures have been realized in this work, we derive estimates of the decay time of mid-infrared plasmons and of their figures of merit for field confinement and for surface plasmon propagation. The average electron scattering rate increases almost linearly with excitation frequency, in agreement with quantum calculations based on a model of the ellipsoidal Fermi surface at the conduction band minimum of germanium accounting for electron scattering with optical phonons and charged impurities. Instead, we found weak dependence of plasmon losses on neutral impurity density. In films where a transient plasma was generated by optical pumping, we found significant dependence of the energy relaxation times in the few-picosecond range on the static doping level of the film, confirming the key but indirect role played by charged impurities in energy relaxation. Our results indicate that underdamped mid-infrared plasma oscillations are attained in n -type-doped germanium at room temperature.

  13. Tunable light filtering by a Bragg mirror/heavily doped semiconducting nanocrystal composite

    PubMed Central

    Kriegel, Ilka

    2015-01-01

    Summary Tunable light filters are critical components for many optical applications in which light in-coupling, out-coupling or rejection is crucial, such as lasing, sensing, photovoltaics and information and communication technology. For this purpose, Bragg mirrors (band-pass filters with high reflectivity) represent good candidates. However, their optical characteristics are determined during the fabrication stage. Heavily doped semiconductor nanocrystals (NCs), on the other hand, deliver a high degree of optical tunability through the active modulation of their carrier density, ultimately influencing their plasmonic absorption properties. Here, we propose the design of an actively tunable light filter composed of a Bragg mirror and a layer of plasmonic semiconductor NCs. We demonstrate that the filtering properties of the coupled device can be tuned to cover a wide range of frequencies from the visible to the near infrared (vis–NIR) spectral region when employing varying carrier densities. As the tunable component, we implemented a dispersion of copper selenide (Cu2−xSe) NCs and a film of indium tin oxide (ITO) NCs, which are known to show optical tunablility with chemical or electrochemical treatments. We utilized the Mie theory to describe the carrier-dependent plasmonic properties of the Cu2−x Se NC dispersion and the effective medium theory to describe the optical characteristics of the ITO film. The transmission properties of the Bragg mirror have been modelled with the transfer matrix method. We foresee ease of experimental realization of the coupled device, where filtering modulation is achieved upon chemical and electrochemical post-fabrication treatment of the heavily doped semiconductor NC component, eventually resulting in tunable transmission properties of the coupled device. PMID:25671163

  14. Radar Absorbing Materials for Cube Stealth Satellite

    NASA Astrophysics Data System (ADS)

    Micheli, D.; Pastore, R.; Vricella, A.; Marchetti, M.

    A Cube Stealth Satellite is proposed for potential applications in defense system. Particularly, the faces of the satellite exposed to the Earth are made of nanostructured materials able to absorb radar surveillance electromagnetic waves, conferring stealth capability to the cube satellite. Microwave absorbing and shielding material tiles are proposed using composite materials consisting in epoxy-resin and carbon nanotubes filler. The electric permittivity of the composite nanostructured materials is measured and discussed. Such data are used by the modeling algorithm to design the microwave absorbing and the shielding faces of the cube satellite. The electromagnetic modeling takes into account for several incidence angles (0-80°), extended frequency band (2-18 GHz), and for the minimization of the electromagnetic reflection coefficient. The evolutionary algorithm used for microwave layered microwave absorber modeling is the recently developed Winning Particle Optimization. The mathematical model of the absorbing structure is finally experimentally validated by comparing the electromagnetic simulation to the measurement of the manufactured radar absorber tile. Nanostructured composite materials manufacturing process and electromagnetic reflection measurements methods are described. Finally, a finite element method analysis of the electromagnetic scattering by cube stealth satellite is performed.

  15. Perfect terahertz absorber using fishnet based metafilm

    SciTech Connect

    Azad, Abul Kalam; Shchegolkov, Dmitry Yu; Chen, Houtong; Taylor, Antoinette; Smirnova, E I; O' Hara, John F

    2009-01-01

    We present a perfect terahertz (THz) absorber working for a broad-angle of incidence. The two fold symmetry of rectangular fishnet structure allows either complete absorption or mirror like reflection depending on the polarization of incident the THz beam. Metamaterials enable the ability to control the electromagnetic wave in a unique fashion by designing the permittivity or permeability of composite materials with desired values. Although the initial idea of metamaterials was to obtain a negative index medium, however, the evolution of metamaterials (MMs) offers a variety of practically applicable devices for controlling electromagnetic wave such as tunable filters, modulators, phase shifters, compact antenna, absorbers, etc. Terahertz regime, a crucial domain of the electromagnetic wave, is suffering from the scarcity of the efficient devices and might take the advantage of metamaterials. Here, we demonstrate design, fabrication, and characterization of a terahertz absorber based on a simple fishnet metallic film separated from a ground mirror plane by a dielectric spacer. Such absorbers are in particular important for bolometric terahertz detectors, high sensitivity imaging, and terahertz anechoic chambers. Recently, split-ring-resonators (SRR) have been employed for metamaterial-based absorbers at microwave and THz frequencies. The experimental demonstration reveals that such absorbers have absorptivity close to unity at resonance frequencies. However, the downside of these designs is that they all employ resonators of rather complicated shape with many fine parts and so they are not easy to fabricate and are sensitive to distortions.

  16. THE SWIFT BAT SURVEY DETECTS TWO OPTICAL BROAD LINE, X-RAY HEAVILY OBSCURED ACTIVE GALAXIES: NVSS 193013+341047 AND IRAS 05218-1212

    SciTech Connect

    Hogg, J. Drew; Winter, Lisa M.; Mushotzky, Richard F.; Reynolds, Christopher S.; Trippe, Margaret E-mail: lisa.winter@colorado.edu

    2012-06-20

    The Swift Burst Alert Telescope (BAT) is discovering interesting new objects while monitoring the sky in the 14-195 keV band. Here we present the X-ray properties and spectral energy distributions (SEDs) for two unusual active galactic nucleus sources. Both NVSS 193013+341047 and IRAS 05218-1212 are absorbed, Compton-thin, but heavily obscured (N{sub H} {approx} 10{sup 23} cm{sup -2}), X-ray sources at redshifts <0.1. The SEDs reveal these galaxies to be very red, with high extinction in the optical and UV. A similar SED is seen for the extremely red objects (EROs) detected in the higher redshift universe. This suggests that these unusual BAT-detected sources are a low-redshift (z << 1) analog to EROs, which recent evidence suggests are a class of the elusive type II quasars. Studying the multi-wavelength properties of these sources may reveal the properties of their high-redshift counterparts.

  17. Solar-energy absorber: Active infrared (IR) trap without glass

    NASA Technical Reports Server (NTRS)

    Brantley, L. W., Jr.

    1974-01-01

    Absorber efficiency can be improved to 90% by removing glass plates and using infrared traps. Absorber configuration may be of interest to manufacturers of solar absorbers and to engineers and scientists developing new sources of energy.

  18. On the definition of absorbed dose

    NASA Astrophysics Data System (ADS)

    Grusell, Erik

    2015-02-01

    Purpose: The quantity absorbed dose is used extensively in all areas concerning the interaction of ionizing radiation with biological organisms, as well as with matter in general. The most recent and authoritative definition of absorbed dose is given by the International Commission on Radiation Units and Measurements (ICRU) in ICRU Report 85. However, that definition is incomplete. The purpose of the present work is to give a rigorous definition of absorbed dose. Methods: Absorbed dose is defined in terms of the random variable specific energy imparted. A random variable is a mathematical function, and it cannot be defined without specifying its domain of definition which is a probability space. This is not done in report 85 by the ICRU, mentioned above. Results: In the present work a definition of a suitable probability space is given, so that a rigorous definition of absorbed dose is possible. This necessarily includes the specification of the experiment which the probability space describes. In this case this is an irradiation, which is specified by the initial particles released and by the material objects which can interact with the radiation. Some consequences are discussed. Specific energy imparted is defined for a volume, and the definition of absorbed dose as a point function involves the specific energy imparted for a small mass contained in a volume surrounding the point. A possible more precise definition of this volume is suggested and discussed. Conclusions: The importance of absorbed dose motivates a proper definition, and one is given in the present work. No rigorous definition has been presented before.

  19. Method of absorbance correction in a spectroscopic heating value sensor

    SciTech Connect

    Saveliev, Alexei; Jangale, Vilas Vyankatrao; Zelepouga, Sergeui; Pratapas, John

    2013-09-17

    A method and apparatus for absorbance correction in a spectroscopic heating value sensor in which a reference light intensity measurement is made on a non-absorbing reference fluid, a light intensity measurement is made on a sample fluid, and a measured light absorbance of the sample fluid is determined. A corrective light intensity measurement at a non-absorbing wavelength of the sample fluid is made on the sample fluid from which an absorbance correction factor is determined. The absorbance correction factor is then applied to the measured light absorbance of the sample fluid to arrive at a true or accurate absorbance for the sample fluid.

  20. Effect of layer thickness on device response of silicon heavily supersaturated with sulfur

    NASA Astrophysics Data System (ADS)

    Hutchinson, David; Mathews, Jay; Sullivan, Joseph T.; Akey, Austin; Aziz, Michael J.; Buonassisi, Tonio; Persans, Peter; Warrender, Jeffrey M.

    2016-05-01

    We report on a simple experiment in which the thickness of a hyperdoped silicon layer, supersaturated with sulfur by ion implantation followed by pulsed laser melting and rapid solidification, is systematically varied at constant average sulfur concentration, by varying the implantation energy, dose, and laser fluence. Contacts are deposited and the external quantum efficiency (EQE) is measured for visible wavelengths. We posit that the sulfur layer primarily absorbs light but contributes negligible photocurrent, and we seek to support this by analyzing the EQE data for the different layer thicknesses in two interlocking ways. In the first, we use the measured concentration depth profiles to obtain the approximate layer thicknesses, and, for each wavelength, fit the EQE vs. layer thickness curve to obtain the absorption coefficient of hyperdoped silicon for that wavelength. Comparison to literature values for the hyperdoped silicon absorption coefficients [S.H. Pan et al. Applied Physics Letters 98, 121913 (2011)] shows good agreement. Next, we essentially run this process in reverse; we fit with Beer's law the curves of EQE vs. hyperdoped silicon absorption coefficient for those wavelengths that are primarily absorbed in the hyperdoped silicon layer, and find that the layer thicknesses obtained from the fit are in good agreement with the original values obtained from the depth profiles. We conclude that the data support our interpretation of the hyperdoped silicon layer as providing negligible photocurrent at high S concentrations. This work validates the absorption data of Pan et al. [Applied Physics Letters 98, 121913 (2011)], and is consistent with reports of short mobility-lifetime products in hyperdoped layers. It suggests that for optoelectronic devices containing hyperdoped layers, the most important contribution to the above band gap photoresponse may be due to photons absorbed below the hyperdoped layer.

  1. Warm Absorber Diagnostics of AGN Dynamics

    NASA Astrophysics Data System (ADS)

    Kallman, Timothy

    Warm absorbers and related phenomena are observable manifestations of outflows or winds from active galactic nuclei (AGN) that have great potential value. Understanding AGN outflows is important for explaining the mass budgets of the central accreting black hole, and also for understanding feedback and the apparent co-evolution of black holes and their host galaxies. In the X-ray band warm absorbers are observed as photoelectric absorption and resonance line scattering features in the 0.5-10 keV energy band; the UV band also shows resonance line absorption. Warm absorbers are common in low luminosity AGN and they have been extensively studied observationally. They may play an important role in AGN feedback, regulating the net accretion onto the black hole and providing mechanical energy to the surroundings. However, fundamental properties of the warm absorbers are not known: What is the mechanism which drives the outflow?; what is the gas density in the flow and the geometrical distribution of the outflow?; what is the explanation for the apparent relation between warm absorbers and the surprising quasi-relativistic 'ultrafast outflows' (UFOs)? We propose a focused set of model calculations that are aimed at synthesizing observable properties of warm absorber flows and associated quantities. These will be used to explore various scenarios for warm absorber dynamics in order to answer the questions in the previous paragraph. The guiding principle will be to examine as wide a range as possible of warm absorber driving mechanisms, geometry and other properties, but with as careful consideration as possible to physical consistency. We will build on our previous work, which was a systematic campaign for testing important class of scenarios for driving the outflows. We have developed a set of tools that are unique and well suited for dynamical calculations including radiation in this context. We also have state-of-the-art tools for generating synthetic spectra, which are

  2. Hydroxide absorption heat pumps with spray absorber

    SciTech Connect

    Summerer, F.; Alefeld, G.; Zeigler, F.; Riesch, P.

    1996-11-01

    The absorber is one of the most expensive components of an absorption heat pump or chiller, respectively. In order to reduce the cost of a heat exchanger, much effort is invested into searching for additives for heat transfer enhancement. Another way to reduce heat exchanger cost, especially for machines with low capacities, is to use an adiabatic spray absorber. The basic principles of the spray absorber is to perform heat and mass transfer separated from each other in two different components. In this way the heat can be rejected effectively in a liquid-liquid heat exchanger, whereas the mass transfer occurs subsequently in a simple vessel. The spray technique can not only save heat exchanger cost in conventional absorption systems working with water and lithium bromide, it also allows the use of quite different working fluids such as hydroxides, which have lower heat transfer coefficients in falling films. Moreover, the separated heat transfer can easily be performed in a liquid-to-air heat exchanger. Hence it is obvious to use hydroxides that allow for a high temperature lift for building an air-cooled chiller with spray absorber. In this presentation theoretical and experimental investigations of the spray absorber as well as the setup will be described. Finally, possible applications will be outlined.

  3. Ultrathin flexible dual band terahertz absorber

    NASA Astrophysics Data System (ADS)

    Shan, Yan; Chen, Lin; Shi, Cheng; Cheng, Zhaoxiang; Zang, Xiaofei; Xu, Boqing; Zhu, Yiming

    2015-09-01

    We propose an ultrathin and flexible dual band absorber operated at terahertz frequencies based on metamaterial. The metamaterial structure consists of periodical split ring resonators with two asymmetric gaps and a metallic ground plane, separated by a thin-flexible dielectric spacer. Particularly, the dielectric spacer is a free-standing polyimide film with thickness of 25 μm, resulting in highly flexible for our absorber and making it promising for non-planar applications such as micro-bolometers and stealth aircraft. Experimental results show that the absorber has two resonant absorption frequencies (0.41 THz and 0.75 THz) with absorption rates 92.2% and 97.4%, respectively. The resonances at the absorption frequencies come from normal dipole resonance and high-order dipole resonance which is inaccessible in the symmetrical structure. Multiple reflection interference theory is used to analyze the mechanism of the absorber and the results are in good agreement with simulated and experimental results. Furthermore, the absorption properties are studied under various spacer thicknesses. This kind of metamaterial absorber is insensitive to polarization, has high absorption rates (over 90%) with wide incident angles range from 0° to 45° and the absorption rates are also above 90% when wrapping it to a curved surface.

  4. Solar absorber material reflectivity measurements at temperature

    SciTech Connect

    Bonometti, J.A.; Hawk, C.W.

    1999-07-01

    Assessment of absorber shell material properties at high operating temperatures is essential to the full understanding of the solar energy absorption process in a solar thermal rocket. A review of these properties, their application and a new experimental methodology to measure them at high temperatures is presented. The direct application for the research is absorber cavity development for a Solar Thermal Upper Stage (STUS). High temperature measurements, greater than 1,000 Kelvin, are difficult to obtain for incident radiation upon a solid surface that forms an absorber cavity in a solar thermal engine. The basic material properties determine the amount of solar energy that is absorbed, transmitted or reflected and are dependent upon the material's temperature. This investigation developed a new approach to evaluate the material properties (i.e., reflectivity, absorptive) of the absorber wall and experimentally determined them for rhenium and niobium sample coupons. The secular reflectivity was measured both at room temperature and at temperatures near 1,000 Kelvin over a range of angles from 0 to 90 degrees. The same experimental measurements were used to calculate the total reflectivity of the sample by integrating the recorded intensities over a hemisphere. The test methodology used the incident solar energy as the heating source while directly measuring the reflected light (an integrated value over all visible wavelengths). Temperature dependence on total reflectivity was found to follow an inverse power function of the material's temperature.

  5. An extremely wideband and lightweight metamaterial absorber

    PubMed Central

    Shen, Yang; Pei, Zhibin; Pang, Yongqiang; Wang, Jiafu; Zhang, Anxue; Qu, Shaobo

    2015-01-01

    This paper presents a three-dimensional microwave metamaterial absorber based on the stand-up resistive film patch array. The absorber has wideband absorption, lightweight, and polarization-independent properties. Our design comes from the array of unidirectional stand-up resistive film patches backed by a metallic plane, which can excite multiple standing wave modes. By rolling the resistive film patches as a square enclosure, we obtain the polarization-independent property. Due to the multiple standing wave modes, the most incident energy is dissipated by the resistive film patches, and thus, the ultra-wideband absorption can be achieved by overlapping all the absorption modes at different frequencies. Both the simulated and experimental results show that the absorber possesses a fractional bandwidth of 148.2% with the absorption above 90% in the frequency range from 3.9 to 26.2 GHz. Moreover, the proposed absorber is extremely lightweight. The areal density of the fabricated sample is about 0.062 g/cm2, which is approximately equivalent to that of eight stacked standard A4 office papers. It is expected that our proposed absorber may find potential applications such as electromagnetic interference and stealth technologies. PMID:26130845

  6. Oxygen absorbers in food preservation: a review.

    PubMed

    Cichello, Simon Angelo

    2015-04-01

    The preservation of packaged food against oxidative degradation is essential to establish and improve food shelf life, customer acceptability, and increase food security. Oxygen absorbers have an important role in the removal of dissolved oxygen, preserving the colour, texture and aroma of different food products, and importantly inhibition of food spoilage microbes. Active packaging technology in food preservation has improved over decades mostly due to the sealing of foods in oxygen impermeable package material and the quality of oxygen absorber. Ferrous iron oxides are the most reliable and commonly used oxygen absorbers within the food industry. Oxygen absorbers have been transformed from sachets of dried iron-powder to simple self-adhesive patches to accommodate any custom size, capacity and application. Oxygen concentration can be effectively lowered to 100 ppm, with applications spanning a wide range of food products and beverages across the world (i.e. bread, meat, fish, fruit, and cheese). Newer molecules that preserve packaged food materials from all forms of degradation are being developed, however oxygen absorbers remain a staple product for the preservation of food and pharmaceutical products to reduce food wastage in developed nations and increased food security in the developing & third world. PMID:25829570

  7. An extremely wideband and lightweight metamaterial absorber

    NASA Astrophysics Data System (ADS)

    Shen, Yang; Pei, Zhibin; Pang, Yongqiang; Wang, Jiafu; Zhang, Anxue; Qu, Shaobo

    2015-06-01

    This paper presents a three-dimensional microwave metamaterial absorber based on the stand-up resistive film patch array. The absorber has wideband absorption, lightweight, and polarization-independent properties. Our design comes from the array of unidirectional stand-up resistive film patches backed by a metallic plane, which can excite multiple standing wave modes. By rolling the resistive film patches as a square enclosure, we obtain the polarization-independent property. Due to the multiple standing wave modes, the most incident energy is dissipated by the resistive film patches, and thus, the ultra-wideband absorption can be achieved by overlapping all the absorption modes at different frequencies. Both the simulated and experimental results show that the absorber possesses a fractional bandwidth of 148.2% with the absorption above 90% in the frequency range from 3.9 to 26.2 GHz. Moreover, the proposed absorber is extremely lightweight. The areal density of the fabricated sample is about 0.062 g/cm2, which is approximately equivalent to that of eight stacked standard A4 office papers. It is expected that our proposed absorber may find potential applications such as electromagnetic interference and stealth technologies.

  8. A model for the high-temperature transport properties of heavily doped n-type silicon-germanium alloys

    NASA Technical Reports Server (NTRS)

    Vining, Cronin B.

    1991-01-01

    A model is presented for the high-temperature transport properties of large-grain-size, heavily doped n-type silicon-germanium alloys. Electron and phonon transport coefficients are calculated using standard Boltzmann equation expressions in the relaxation time approximation. Good agreement with experiment is found by considering acoustic phonon and ionized impurity scattering for electrons, and phonon-phonon, point defect, and electron-phonon scattering for phonons. The parameters describing electron transport in heavily doped and lightly doped materials are significantly different and suggest that most carriers in heavily doped materials are in a band formed largely from impurity states. The maximum dimensionless thermoelectric figure of merit for single-crystal, n-type Si(0.8)Ge(0.2) at 1300 K is estimated at ZT about 1.13 with an optimum carrier concentration of n about 2.9 x 10 to the 20th/cu cm.

  9. Circular polarization sensitive absorbers based on graphene

    PubMed Central

    Yang, Kunpeng; Wang, Min; Pu, Mingbo; Wu, Xiaoyu; Gao, Hui; Hu, Chenggang; Luo, Xiangang

    2016-01-01

    It is well known that the polarization of a linearly polarized (LP) light would rotate after passing through a single layer graphene under the bias of a perpendicular magnetostatic field. Here we show that a corresponding phase shift could be expected for circularly polarized (CP) light, which can be engineered to design the circular polarization sensitive devices. We theoretically validate that an ultrathin graphene-based absorber with the thickness about λ/76 can be obtained, which shows efficient absorption >90% within incident angles of ±80°. The angle-independent phase shift produced by the graphene is responsible for the nearly omnidirectional absorber. Furthermore, a broadband absorber in frequencies ranging from 2.343 to 5.885 THz with absorption over 90% is designed by engineering the dispersion of graphene. PMID:27034257

  10. Ferrite HOM Absorber for the RHIC ERL

    SciTech Connect

    Hahn,H.; Choi, E.M.; Hammons, L.

    2008-10-01

    A superconducting Energy Recovery Linac is under construction at Brookhaven National Laboratory to serve as test bed for RHIC upgrades. The damping of higher-order modes in the superconducting five-cell cavity for the Energy-Recovery linac at RHIC is performed exclusively by two ferrite absorbers. The ferrite properties have been measured in ferrite-loaded pill box cavities resulting in the permeability values given by a first-order Debye model for the tiled absorber structure and an equivalent permeability value for computer simulations with solid ring dampers. Measured and simulated results for the higher-order modes in the prototype copper cavity are discussed. First room-temperature measurements of the finished niobium cavity are presented which confirm the effective damping of higher-order modes in the ERL. by the ferrite absorbers.

  11. Temporal, latitude and altitude absorbed dose dependences

    NASA Astrophysics Data System (ADS)

    Stozhkov, Y.; Svirzhevsky, N.; Bazilevskaya, G.

    The regular balloon measurements in the Earth's atmosphere are carried on at the Lebedev Physical Institute since 1957. The regular balloon flights have been made at the high latitude stations (near Murmansk - northern hemisphere and Mi ny -r Antarctica) and at the middle latitude (Moscow). Based on these long-term measurements as well as on the latitude data obtained in the several Soviet Antarctic expeditions the calculations of absorbed doses were fulfilled for altitudes of 10, 15, 20 and 30 km. The absorbed dose dependences on the geomagnetic cutoff rigidities and the phase of the 11-year solar cycle were found. The evaluation of the solar proton events and energetic electron precipitation contributions to the absorbed dose enhancements was made.

  12. Circular polarization sensitive absorbers based on graphene

    NASA Astrophysics Data System (ADS)

    Yang, Kunpeng; Wang, Min; Pu, Mingbo; Wu, Xiaoyu; Gao, Hui; Hu, Chenggang; Luo, Xiangang

    2016-04-01

    It is well known that the polarization of a linearly polarized (LP) light would rotate after passing through a single layer graphene under the bias of a perpendicular magnetostatic field. Here we show that a corresponding phase shift could be expected for circularly polarized (CP) light, which can be engineered to design the circular polarization sensitive devices. We theoretically validate that an ultrathin graphene-based absorber with the thickness about λ/76 can be obtained, which shows efficient absorption >90% within incident angles of ±80°. The angle-independent phase shift produced by the graphene is responsible for the nearly omnidirectional absorber. Furthermore, a broadband absorber in frequencies ranging from 2.343 to 5.885 THz with absorption over 90% is designed by engineering the dispersion of graphene.

  13. Absorber Materials at Room and Cryogenic Temperatures

    SciTech Connect

    F. Marhauser, T.S. Elliott, A.T. Wu, E.P. Chojnacki, E. Savrun

    2011-09-01

    We recently reported on investigations of RF absorber materials at cryogenic temperatures conducted at Jefferson Laboratory (JLab). The work was initiated to find a replacement material for the 2 Kelvin low power waveguide Higher Order Mode (HOM) absorbers employed within the original cavity cryomodules of the Continuous Electron Beam Accelerator Facility (CEBAF). This effort eventually led to suitable candidates as reported in this paper. Furthermore, though constrained by small funds for labor and resources, we have analyzed a variety of lossy ceramic materials, several of which could be usable as HOM absorbers for both normal conducting and superconducting RF structures, e.g. as loads in cavity waveguides and beam tubes either at room or cryogenic temperatures and, depending on cooling measures, low to high operational power levels.

  14. Spatial-frequency multiplication via absorbance modulation

    SciTech Connect

    Tsai, H.-Y.; Wallraff, Gregory M.; Menon, Rajesh

    2007-08-27

    The absorbance of a thin film of photochromic material can be reversibly modified by exposure to two different wavelengths, {lambda}{sub 1} and {lambda}{sub 2}. When such a film is illuminated by both wavelengths simultaneously, and the longer wavelength {lambda}{sub 2} possesses a node in its intensity distribution, then the absorbance of the layer can be made high except at an arbitrarily small region near the node. By exploiting the large nonlinearity introduced by this mechanism, combined with the reversibility of the absorbance of the photochromic layer, the authors demonstrate that spatial frequencies larger than those present in incident intensity distributions may be generated. They show photoresist exposures to demonstrate this technique.

  15. A Dynamic Absorber With Active Vibration Control

    NASA Astrophysics Data System (ADS)

    Huang, S.-J.; Lian, R.-J.

    1994-12-01

    The design and construction of a dynamic absorber incorporating active vibration control is described. The absorber is a two-degrees-of-freedom spring — lumped mass system sliding on a guide pillar, with two internal vibration disturbance sources. Both the main mass and the secondary absorber mass are acted on by DC servo motors, respectively, to suppress the vibration amplitude. The state variable technique is used to model this dynamic system and a decoupling PID control method is used. First, the discrete time state space model is identified by using the commercial software MATLAB. Then the decoupling controller of this multi-input/multi-output system is derived from the identified model. Finally the results of some experiments are presented. The experimental results show that the system is effective in suppressing vibration. Also, the performance of this control strategy for position tracking control is evaluated based on experimental data.

  16. Photoexited switchable metamaterial absorber at terahertz frequencies

    NASA Astrophysics Data System (ADS)

    Xu, Zongcheng; Gao, Runmei; Ding, Chunfeng; Wu, Liang; Zhang, Yating; Xu, Degang; Yao, Jianquan

    2015-06-01

    We propose a design and numerical study of an optically switchable metamaterial absorber in the terahertz regime. The metamaterial absorber comprises a periodic array of metallic split-ring resonators sitting back to back with an embedded semiconductor silicon. Filing the gap between the resonator arms with a semiconductor (silicon), leads to easy modification of its optical response through a pump beam which changes conductivity of Si. The conductivity of silicon is a function of incident pump power. Therefore, the resonance frequencies of the metamaterial can be tunable by applying an external pump power. The resonance peak of the absorption spectra shows a shift from 1.17 to 0.68 THz via external optical stimulus, with granting a resonance tuning range on the order of 42%. The optical-tuned absorber has potential applications as a terahertz modulator and switchable device and offer a step forward in filling the "THz gap".

  17. Non-Absorbable Gas Behavior in the Absorber/Evaporator of a Absorption Chiller

    NASA Astrophysics Data System (ADS)

    Suzuki, Hiroshi; Nagamoto, Wataru; Sugiyama, Takahide

    A two-dimensional numerical study on non-absorbable gas behavior in the absorber/evaporator of an absorption chiller has been performed. In the present study, the effect of the pitch-to-diameter ratio of a cylinder bundle in the absorber was highlighted. From the results, a sudden decrease of the overall heat transfer coefficient of the absorber was observed at a certain mean concentration of non-absorbable gas for each pitch-to-diameter ratio. Such a critical concentration was also found to decrease as the pitch-to- diameter ratio increased. The sudden decrease occurs due to the sudden disappearance of recirculating region, which is formed between the absorber and the evaporator, and where most of non-absorbable gas stays when it exists. As the pitch-to-diameter ratio increases, the recirculating region becomes weak because the velocity of the high velocity region supporting the recirculating flow decreases. Then, the critical mean concentration of non-absorbable gas is found to decrease as pitch-to-ratio increases.

  18. Direct search for a ferromagnetic phase in a heavily overdoped nonsuperconducting copper oxide.

    PubMed

    Sonier, J E; Kaiser, C V; Pacradouni, V; Sabok-Sayr, S A; Cochrane, C; MacLaughlin, D E; Komiya, S; Hussey, N E

    2010-10-01

    The doping of charge carriers into the CuO(2) planes of copper oxide Mott insulators causes a gradual destruction of antiferromagnetism and the emergence of high-temperature superconductivity. Optimal superconductivity is achieved at a doping concentration p beyond which further increases in doping cause a weakening and eventual disappearance of superconductivity. A potential explanation for this demise is that ferromagnetic fluctuations compete with superconductivity in the overdoped regime. In this case, a ferromagnetic phase at very low temperatures is predicted to exist beyond the doping concentration at which superconductivity disappears. Here we report on a direct examination of this scenario in overdoped La(2-x)Sr(x)CuO(4) using the technique of muon spin relaxation. We detect the onset of static magnetic moments of electronic origin at low temperature in the heavily overdoped nonsuperconducting region. However, the magnetism does not exist in a commensurate long-range ordered state. Instead it appears as a dilute concentration of static magnetic moments. This finding places severe restrictions on the form of ferromagnetism that may exist in the overdoped regime. Although an extrinsic impurity cannot be absolutely ruled out as the source of the magnetism that does occur, the results presented here lend support to electronic band calculations that predict the occurrence of weak localized ferromagnetism at high doping. PMID:20855579

  19. High-quality male field crickets invest heavily in sexual display but die young.

    PubMed

    Hunt, John; Brooks, Robert; Jennions, Michael D; Smith, Michael J; Bentsen, Caroline L; Bussière, Luc F

    2004-12-23

    Only high-quality males can bear the costs of an extreme sexual display. As a consequence, such males are not only more attractive, but they often live longer than average. Recent theory predicts, however, that high-quality males should sometimes invest so heavily in sexual displays that they die sooner than lower quality males. We manipulated the phenotypic quality of field crickets, Teleogryllus commodus, by altering the protein content of their diet. Here we show that nymphs and adult females reared on a high-protein diet lived longer than those on a low-protein diet. In contrast, adult males reared on a high-protein diet died sooner than those on low-protein diets because they invested more energy in calling during early adulthood. Our findings uphold the theoretical prediction that the relationship between longevity and sexual advertisement may be dynamic (that is, either positive or negative), depending on local conditions such as resource availability. Moreover, they caution the use of longevity as a proxy for fitness in sexual selection studies, and suggest avenues for future research on the relationship between sexual attractiveness and ageing. PMID:15616562

  20. Multielemental analysis of 20 mushroom species growing near a heavily trafficked road in Poland.

    PubMed

    Mleczek, M; Niedzielski, P; Kalač, P; Budka, A; Siwulski, M; Gąsecka, M; Rzymski, P; Magdziak, Z; Sobieralski, K

    2016-08-01

    The aim of this work was to compare 10 mostly edible aboveground and 10 wood-growing mushroom species collected near a heavily trafficked road (approximately 28,000 vehicles per 24 h) in Poland with regard to their capacity to accumulate 26 trace elements (Ag, Al, As, Au, B, Ba, Bi, Cd, Co, Cr, Cu, Fe, Ga, Ge, In, Li, Mn, Ni, Pb, Re, Sb, Se, Sr, Te, Tl, and Zn) in their fruit bodies in order to illustrate mushroom diversity in element accumulation. All analyses were performed using an inductively coupled plasma optical emission spectrometry (ICP-OES) spectrometer in synchronous dual view mode. The aboveground species had significantly higher levels of 12 elements, including Ag, As, Pb, and Se, compared to the wood-growing species. An opposite relationship was observed only for Au, Ba, and Sr. The results of principal component analysis (PCA) and hierarchical cluster analysis (HCA) implied some new relationships among the analyzed species and elements. Of the analyzed mushroom species, lead content in Macrolepiota procera would seem to pose a health risk; however, at present knowledge regarding lead bioaccessibility from mushrooms is quite limited. PMID:27155831

  1. Direct search for a ferromagnetic phase in a heavily overdoped nonsuperconducting copper oxide

    PubMed Central

    Sonier, J. E.; Kaiser, C. V.; Pacradouni, V.; Sabok-Sayr, S. A.; Cochrane, C.; MacLaughlin, D. E.; Komiya, S.; Hussey, N. E.

    2010-01-01

    The doping of charge carriers into the CuO2 planes of copper oxide Mott insulators causes a gradual destruction of antiferromagnetism and the emergence of high-temperature superconductivity. Optimal superconductivity is achieved at a doping concentration p beyond which further increases in doping cause a weakening and eventual disappearance of superconductivity. A potential explanation for this demise is that ferromagnetic fluctuations compete with superconductivity in the overdoped regime. In this case, a ferromagnetic phase at very low temperatures is predicted to exist beyond the doping concentration at which superconductivity disappears. Here we report on a direct examination of this scenario in overdoped La2-xSrxCuO4 using the technique of muon spin relaxation. We detect the onset of static magnetic moments of electronic origin at low temperature in the heavily overdoped nonsuperconducting region. However, the magnetism does not exist in a commensurate long-range ordered state. Instead it appears as a dilute concentration of static magnetic moments. This finding places severe restrictions on the form of ferromagnetism that may exist in the overdoped regime. Although an extrinsic impurity cannot be absolutely ruled out as the source of the magnetism that does occur, the results presented here lend support to electronic band calculations that predict the occurrence of weak localized ferromagnetism at high doping. PMID:20855579

  2. An automatic locally-adaptive method to estimate heavily-tailed breakthrough curves from particle distributions

    NASA Astrophysics Data System (ADS)

    Pedretti, Daniele; Fernàndez-Garcia, Daniel

    2013-09-01

    Particle tracking methods to simulate solute transport deal with the issue of having to reconstruct smooth concentrations from a limited number of particles. This is an error-prone process that typically leads to large fluctuations in the determined late-time behavior of breakthrough curves (BTCs). Kernel density estimators (KDE) can be used to automatically reconstruct smooth BTCs from a small number of particles. The kernel approach incorporates the uncertainty associated with subsampling a large population by equipping each particle with a probability density function. Two broad classes of KDE methods can be distinguished depending on the parametrization of this function: global and adaptive methods. This paper shows that each method is likely to estimate a specific portion of the BTCs. Although global methods offer a valid approach to estimate early-time behavior and peak of BTCs, they exhibit important fluctuations at the tails where fewer particles exist. In contrast, locally adaptive methods improve tail estimation while oversmoothing both early-time and peak concentrations. Therefore a new method is proposed combining the strength of both KDE approaches. The proposed approach is universal and only needs one parameter (α) which slightly depends on the shape of the BTCs. Results show that, for the tested cases, heavily-tailed BTCs are properly reconstructed with α ≈ 0.5 .

  3. [Direct removal of typical endocrine disruptors from heavily polluted river water by ozonation].

    PubMed

    Wang, Ling-yun; Zhang, Xi-hui; Song, Qian-wu

    2011-05-01

    Ozone was applied to study the removal of conventional pollutants and typical endocrine disrupters (EDs), including bisphenol A (BPA), 4-n-nonylphenol(NP), 4-tert-octylphenol (OP), estrone (E1), estradiol (E2), 17alpha-estradiol (17alpha-E2), estriol (E3) and ethinylestradiol (EE2) , from heavily polluted river water. The O3 dose was designed at 28 mg x L(-1) for 30 min and 42 mg x L(-1) for 80 min. Pollutants in terms of chemical oxygen demand (COD) and ammonia nitrogen can not be removed efficiently, ranged from 3% to 7%. The colority of the black water was quickly reduced in the first 5 minutes, while the turbidities increased first and then decreased gradually. It showed that three EDs with relatively high level including BPA, OP and EE2 could be removed efficiently in thirty minutes. Concentrations of E3 increased first then decreased to be lower than the detection limit. Removal efficiencies of E1 and E2 were 41%-70% and 62%-85% respectively. Extension of ozone exposure time can not improve the efficiency of EDs removal any more. PMID:21780591

  4. High critical currents in heavily doped (Gd,Y)Ba2Cu3Ox superconductor tapes

    DOE PAGESBeta

    Selvamanickam, V.; Gharahcheshmeh, M. Heydari; Xu, A.; Galstyan, E.; Delgado, L.; Cantoni, C.

    2015-01-20

    REBa2Cu3Ox superconductor tapes with moderate levels of dopants have been optimized for high critical current density in low magnetic fields at 77 K, but they do not exhibit exemplary performance in conditions of interest for practical applications, i.e., temperatures less than 50 K and fields of 2–30 T. Heavy doping of REBCO tapes has been avoided by researchers thus far due to deterioration in properties. Here, we report achievement of critical current densities (Jc) above 20 MA/cm2 at 30 K, 3 T in heavily doped (25 mol. % Zr-added) (Gd,Y)Ba2Cu3Ox superconductor tapes, which is more than three times higher thanmore » the Jc typically obtained in moderately doped tapes. Pinning force levels above 1000 GN/m3 have also been attained at 20 K. A composition map of lift factor in Jc (ratio of Jc at 30 K, 3 T to the Jc at 77 K, 0 T) has been developed which reveals the optimum film composition to obtain lift factors above six, which is thrice the typical value. A highly c-axis aligned BaZrO3 (BZO) nanocolumn defect density of nearly 7 × 1011 cm–2 as well as 2–3nm sized particles rich in Cu and Zr have been found in the high Jc films.« less

  5. Heavily T2-Weighted Magnetic Resonance Landmarks of the Cavernous Sinus and Paracavernous Region

    PubMed Central

    Hermann, M.; Bobek-Billewicz, B.; Sloniewski, P.

    2000-01-01

    The purpose of this study was to evaluate the magnetic resonance anatomy of the cavernous sinus. Heavily T2-weighted submillimetric sequence in sagittal, coronal, and axial planes was performed in 16 healthy patients. The sequence provides high contrast between fluid and other structures of the cavernous sinus. High signal intensity of the venous spaces of the cavernous sinus provides a kind of a background for internal carotid artery, cranial nerves, and meninges, as well as bony and fibrous structures. The study was performed with the help of an anatomic atlas. Different magnetic resonance (MR) landmarks of the cavernous and parasellar region were introduced and demonstrated. MR images, superior to computer tomography, allow a detailed assessment of the cavernous sinus anatomy. Delineation by magnetic resonance of tiny anatomical structures may help the neurosurgeon trace the exact outline of a tumor and help to plan an adequate strategy if complete resection is attempted. ImagesFigure 1Figure 2Figure 3Figure 4Figure 5Figure 6Figure 8 PMID:17171105

  6. Modeling approaches to management of nitrate contamination of groundwater in a heavily cultivated area

    NASA Astrophysics Data System (ADS)

    Koh, E.; Park, Y.; Lee, K.

    2011-12-01

    A three-dimensional variably-saturated groundwater flow and reactive transport modeling framework was implemented to simulate nitrate contamination in a heavily cultivated area in Jeju volcanic Island. In the study area, two localized aquifer systems (perched and regional groundwater) exist due to distributions of impermeable clay layers beneath the perched groundwater. The approximate application rate of chemical fertilizers was surveyed to be 627.9 kg-N/ha per year, which is much higher than the average annual chemical fertilizer usage in Jeju Island, 172 kg-N/ha per year. Severe nitrate contamination has been observed in the perched groundwater system and such perched groundwater has influenced regional groundwater quality, through poorly cemented wall of the distributed throughout the region wells. For a part of managing plan of nitrate contamination in the island, a numerical modeling framework was developed for various scenarios associated with the factors affecting nitrate contamination in the study area (i.e., usage amount of chemical fertilizers, cultivated methods, grouting condition of wells). This work provides useful information to suggest effective ways to manage nitrate contamination of groundwater in the agricultural field. Acknowledgements: This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology (2011-0001120) and by BK21 project of Korean Government.

  7. Evolution of microstructure and texture during recovery and recrystallization in heavily rolled aluminum

    NASA Astrophysics Data System (ADS)

    Mishin, O. V.; Godfrey, A.; Yu, T.; Hansen, N.; Jensen, D. Juul

    2015-04-01

    The annealing behavior of nanostructured aluminum AA1050 prepared by cold rolling to an ultrahigh strain (εvM = 6.4) has been investigated using both transmission electron microscopy and electron backscatter diffraction techniques, paying particular attention to changes in microstructure and texture during recovery and their influence on subsequent recrystallization. It is found that coarsening of lamellar structures during recovery can occur via triple junction motion, and that this process can modify the proportion of different boundary types and texture components compared to those in the cold rolled material. Additionally, the heavily deformed material is characterized by different textures and different spatial arrangements of rolling texture components in the center and subsurface. It is found that changes in the misorientation distribution and texture during coarsening are greatly affected by the initial spatial distribution of crystallographic orientations. In particular, the reduction in the fraction of high angle boundaries observed during recovery is much more pronounced in the subsurface layers than in the center layer. The initial through-thickness heterogeneity is thus greatly enhanced during recovery, which leads to significant differences in recrystallized microstructure and texture in the different layers.

  8. Boron deactivation in heavily boron-doped Czochralski silicon during rapid thermal anneal: Atomic level understanding

    SciTech Connect

    Gao, Chao; Dong, Peng; Yi, Jun; Ma, Xiangyang E-mail: mxyoung@zju.edu.cn; Yang, Deren; Lu, Yunhao E-mail: mxyoung@zju.edu.cn

    2014-01-20

    The changes in hole concentration of heavily boron (B)-doped Czochralski silicon subjected to high temperature rapid thermal anneal (RTA) and following conventional furnace anneal (CFA) have been investigated. It is found that decrease in hole concentration, namely, B deactivation, is observed starting from 1050 °C and increases with RTA temperature. The following CFA at 300–500 °C leads to further B deactivation, while that at 600–800 °C results in B reactivation. It is supposed that the interaction between B atoms and silicon interstitials (I) thus forming BI pairs leads to the B deactivation during the high temperature RTA, and, moreover, the formation of extended B{sub 2}I complexes results in further B deactivation in the following CFA at 300–500 °C. On the contrary, the dissociation of BI pairs during the following CFA at 600–800 °C enables the B reactivation. Importantly, the first-principles calculation results can soundly account for the above-mentioned supposition.

  9. Surface passivation of heavily boron or phosphorus doped crystalline silicon utilizing amorphous silicon

    NASA Astrophysics Data System (ADS)

    Carstens, K.; Dahlinger, M.

    2016-05-01

    Excellent surface passivation of heavily boron or phosphorus doped crystalline silicon is presented utilizing undoped hydrogenated amorphous silicon (a-Si:H). For passivating boron doped crystalline silicon surfaces, amorphous silicon needs to be deposited at low temperatures 150°C ≤Tdep≤200°C , leading to a high bandgap. In contrast, low bandgap amorphous silicon causes an inferior surface passivation of highly boron doped crystalline silicon. Boron doping in crystalline silicon leads to a shift of the Fermi energy towards the valence band maximum in the undoped a-Si:H. A simulation, implementing dangling bond defects according to the defect pool model, shows this shift in the undoped a-Si:H passivation to be more pronounced if the a-Si:H has a lower bandgap. Hence, the inferior passivation of boron doped surfaces with low bandgap amorphous silicon stems from a lower silicon-hydrogen bond energy due to this shift of the Fermi energy. Hydrogen effusion and ellipsometry measurements support our interpretation.

  10. Alkylphenolic compounds and bisphenol A contamination within a heavily urbanized area: case study of Paris.

    PubMed

    Cladière, Mathieu; Gasperi, Johnny; Lorgeoux, Catherine; Bonhomme, Céline; Rocher, Vincent; Tassin, Bruno

    2013-05-01

    This study evaluates the influence of a heavily urbanized area (Paris Metropolitan area), on receiving water contamination by both bisphenol A (BPA) and alkylphenol ethoxylate (APE) biodegradation product. The study began by investigating concentrations within urban sources. In addition to the more commonly studied wastewater treatment plant effluent, wet weather urban sources (including combined sewer overflows, urban runoff, and total atmospheric fallout) were considered. The initial results highlight a significant contamination of all urban sources (from a few nanograms per liter in atmospheric fallout to several micrograms per liter in the other sources) with clearly distinguishable distribution patterns. Secondly, concentration changes along the Seine River from upstream of the Paris Metropolitan area to downstream were investigated. While the concentrations of BPA and nonylphenoxy acetic acid (NP₁EC) increase substantially due to urban sources, the 4-nonylphenol concentrations remain homogeneous along the Seine. These results suggest a broad dissemination of 4-nonylphenol at the scale of the Seine River basin. Moreover, the relationship between pollutant concentrations and Seine River flow was assessed both upstream and downstream of the Paris conurbation. Consequently, a sharp decrease in dissolved NP1EC concentrations relative to Seine River flow underscores the influence of single-point urban pollution on Seine River contamination. Conversely, dissolved 4-nonylphenol concentrations serve to reinforce the hypothesis of its widespread presence at the Seine River basin scale. PMID:23054786

  11. Mechanism of insulator-to-metal transition in heavily Nb doped anatase TiO2

    NASA Astrophysics Data System (ADS)

    Tao, Junguang; Pan, H.; Wong, Lai Mun; Wong, Ten It; Chai, J. W.; Pan, Jisheng; Wang, S. J.

    2014-03-01

    Heavily Nb-doped anatase TiO2 (TNO) thin films were prepared by pulsed dc magnetron sputtering using an Nb-doped TiO2 target. The as-grown films exhibit high resistivity whose resistance decreases by ˜2 × 104-fold upon vacuum annealing. The ˜40% Nb-doped anatase TiO2 film shows a low resistivity of 5.7 × 10-4 Ω cm and a high electron concentration of 3.07 × 1021 cm-3. Combined in situ x-ray photoelectron spectroscopy (XPS) measurement and density-functional theory (DFT) calculations show that oxygen interstitial (Oint) and Nb interstitial (Nbint) defect clusters introduce localized shallow p-type accepter states that trap the electrons and reduce the conductivity. These defect clusters can be eliminated by vacuum annealing which is companied by outward diffusion of Nb. As a result, the trapped electrons backfill the Ti sites which are delocalized to promote conductivity.

  12. Precise Th/U-dating of small and heavily coated samples of deep sea corals

    NASA Astrophysics Data System (ADS)

    Lomitschka, Michael; Mangini, Augusto

    1999-07-01

    Marine carbonate skeletons like deep-sea corals are frequently coated with iron and manganese oxides/hydroxides which adsorb additional thorium and uranium out of the sea water. A new cleaning procedure has been developed to reduce this contamination. In this further cleaning step a solution of Na 2EDTA (Na 2H 2T B) and ascorbic acid is used which composition is optimised especially for samples of 20 mg of weight. It was first tested on aliquots of a reef-building coral which had been artificially contaminated with powdered ferromanganese nodule. Applied on heavily contaminated deep-sea corals (scleractinia), it reduced excess 230Th by another order of magnitude in addition to usual cleaning procedures. The measurement of at least three fractions of different contamination, together with an additional standard correction for contaminated carbonates results in Th/U-ages corrected for the authigenic component. A good agreement between Th/U- and 14C-ages can be achieved even for extremely coated corals.

  13. Seasonal variability of ultra-fine metals downwind of a heavily traveled secondary road

    NASA Astrophysics Data System (ADS)

    Cahill, Thomas A.; Barnes, David E.; Spada, Nicholas J.

    2014-09-01

    Since 2002, we have been studying the impact of a heavily traveled secondary road on an adjacent downwind school located at a stop light controlled intersection. The prior studies were all performed in winter conditions with typically strong inversions, but established significant PM2.5 impacts on the school roughly in accord with theoretical models and the relevant literature. In this project, we have enhanced this effort by extending the study from winter to summer, and adding compositionally-resolved ultra-fine aerosol measurements. Ultra-fine aerosols, including metals derived from both brake wear and zinc in lubricating oil, were present at high concentrations in winter downwind of the roadway but absent at a residential site 500 m upwind. Their concentrations faded to minor levels in spring and early summer, while coarse roadway resuspended dust increased in that period. A comparison of ultra-fine measurements in downtown Sacramento and other California Central Valley sites indicates that these traffic derived aerosols are widely present in urban areas impacted by heavy traffic, freeways and secondary streets, especially where heavy braking is occurring. The potential for health impacts of ultra-fine metals associated with cars braking and accelerating in inversion conditions is a serious health concern based on recent epidemiological studies.

  14. Rapid-thermal-processing-based internal gettering for heavily boron-doped Czochralski silicon

    NASA Astrophysics Data System (ADS)

    Fu, Liming; Yang, Deren; Ma, Xiangyang; Tian, Daxi; Que, Duanlin

    2006-11-01

    The effect of rapid-thermal processing (RTP) ambients on the formation of oxygen precipitates and denuded zone (DZ) in heavily boron-doped (HB) Czochralski (Cz) silicon by a low-high (L-H) two-step annealing (800°C/4h+1000°C/16h) has been investigated. It was found that after the L-H two-step annealing, there was a high density of bulk microdefects (BMDs) and no observable DZ was formed near the surface in HB Cz silicon wafers preannealed by the RTP in Ar ambient, while the BMD density was quite low in HB Cz silicon wafers preannealed by the RTP in O2 ambient. However, applying the preannealing of RTP sequentially in Ar and O2 ambients allowed us to obtain a high density of BMDs in combination with a sufficient DZ by the subsequent L-H two-step annealing. This approach offers a pathway to optimize internal gettering for HB Cz silicon.

  15. The stability of butyltin compounds in a dredged heavily-contaminated sediment.

    PubMed

    Saeki, Kazutoshi; Nabeshima, Akiko; Kunito, Takashi; Oshima, Yuji

    2007-06-01

    A treatment process for marine sediment heavily contaminated with tributyltin (TBT) was designed that included dehydrating, sunlight drying and dumping processes. The time course in butyltin (BTs) compounds, TBT, dibutyltin (DBT) and monobutyltin concentrations were investigated in the sediment treated under various conditions (light (UV, sunlight and light exclusion), moisture (air-drying and water saturation) and wetting and drying cycles). Significant changes in all the BT compound concentrations with time were not found regardless of the sediment conditions for light and moisture. The results indicated the high stabilities of TBT and DBT in the sediments versus light and moisture condition changes, probably taking place in the treatment process. It is also estimated that the BTs in the sediment are resistant to photo-degradation and biochemical degradation and their half lives are relatively long. In contrast, the decreases in the TBT and DBT were observed during the wetting and drying cycle treatment for the water saturated sediment both during exposure to sunlight and under a dark condition. This result suggested the hypothesis that the TBT degradation could be accelerated by the high microbial activity induced by the moisture changing treatments. PMID:17368724

  16. Three Dimensional Stress Maps of Dynamic Hydraulic Fracture within Heavily Cross-Linked Hydrogels

    NASA Astrophysics Data System (ADS)

    Steinhardt, W.; Rubinstein, S.; Weitz, D.

    2014-12-01

    Hydraulic fractures (HFs) of oil and gas shales occur miles underground, below complex, layered heterogeneous rocks making any measurements of their dynamics, extent, or structure difficult to impossible. As such, model lab systems such as blocks of PMMA or rocks fractured with air or fluid (Bunger et al [2013], Alpern et al [2012]) are studied in order to understand the intricacies of HFs. However, due to the extreme energies necessary to fracture these materials the experiments are difficult, have little flexibility in the materials, and offer little no measure of the dynamics of the fracture. Heavily cross-linked hydrogels have been shown to be a good model to study brittle fracture (Livne et al [2004]). I will discuss a new system, which we have developed to study HFs within tough hydrogels which have the benefits of having highly tunable rheology, being optically clear, and having slower fracture speeds and breakdown pressures. By embedding fluorescent tracer particles within the gel together with laser sheet microscopy, we obtain the three dimensional stress and strain maps of the zone surrounding a hydraulic fracture tip.

  17. Microbial leaching of toxic metals and arsenic from a heap consisting of heavily polluted soil

    NASA Astrophysics Data System (ADS)

    Groudev, Stoyan; Georgiev, Plamen; Spasova, Irena; Nicolova, Marina

    2014-05-01

    Soil heavily polluted with toxic heavy metals (mainly Cu, Zn, Cd) and arsenic was subjected to microbial cleanup in a heap specially constructed for this purpose. The heap was located on an impermeable geomembrane, had the shape of a truncated pyramid and contained about 240 tons of soil collected mainly from the horizon A. The soil was highly acidic (with an initial pH of about 3.2) and was preliminarily crushed to minus 2.5 cm particle size. The pollutants were present mainly as the relevant sulphide minerals and the soil was inhabited by different microorganisms, including some acidophilic chemolithotrophic bacteria able to oxidize sulphides and to solubilize the relevant toxic elements. The heap possessed systems for irrigation and aeration and was surrounded by ditches to collect the drainage heap effluents containing the dissolved pollutants. The treatment of the soil was carried out by means of interrupted irrigation with leach solutions containing diluted sulphuric acid (to maintain pH in the heap within the range of about 2.5 - 2.8) and ammonium and phosphate ions to maintain the microbial growth. The treatment was carried out for a period of about two years during different climatic seasons. After the end of leaching the soil was subjected to some conventional melioration procedures such as liming, grassing, moulching, addition of fertilizers and animal manure and periodic ploughing and irrigation to increase its quality to levels suitable for agricultural utilization.

  18. Electrical activation of nitrogen heavily implanted 3C-SiC(1 0 0)

    NASA Astrophysics Data System (ADS)

    Li, Fan; Sharma, Yogesh; Shah, Vishal; Jennings, Mike; Pérez-Tomás, Amador; Myronov, Maksym; Fisher, Craig; Leadley, David; Mawby, Phil

    2015-10-01

    A degenerated wide bandgap semiconductor is a rare system. In general, implant levels lie deeper in the band-gap and carrier freeze-out usually takes place at room temperature. Nevertheless, we have observed that heavily doped n-type degenerated 3C-SiC films are achieved by nitrogen implantation level of ∼6 × 1020 cm-3 at 20 K. According to temperature dependent Hall measurements, nitrogen activation rates decrease with the doping level from almost 100% (1.5 × 1019 cm-3, donor level 15 meV) to ∼12% for 6 × 1020 cm-3. Free donors are found to saturate in 3C-SiC at ∼7 × 1019 cm-3. The implanted film electrical performances are characterized as a function of the dopant doses and post implantation annealing (PIA) conditions by fabricating Van der Pauw structures. A deposited SiO2 layer was used as the surface capping layer during the PIA process to study its effect on the resultant film properties. From the device design point of view, the lowest sheet resistivity (∼1.4 mΩ cm) has been observed for medium doped (4 × 1019 cm-3) sample with PIA 1375 °C 2 h without a SiO2 cap.

  19. Determinants of community structure of zooplankton in heavily polluted river ecosystems

    PubMed Central

    Xiong, Wei; Li, Jie; Chen, Yiyong; Shan, Baoqing; Wang, Weimin; Zhan, Aibin

    2016-01-01

    River ecosystems are among the most affected habitats globally by human activities, such as the release of chemical pollutants. However, it remains largely unknown how and to what extent many communities such as zooplankton are affected by these environmental stressors in river ecosystems. Here, we aim to determine major factors responsible for shaping community structure of zooplankton in heavily polluted river ecosystems. Specially, we use rotifers in the Haihe River Basin (HRB) in North China as a case study to test the hypothesis that species sorting (i.e. species are “filtered” by environmental factors and occur at environmental suitable sites) plays a key role in determining community structure at the basin level. Based on an analysis of 94 sites across the plain region of HRB, we found evidence that both local and regional factors could affect rotifer community structure. Interestingly, further analyses indicated that local factors played a more important role in determining community structure. Thus, our results support the species sorting hypothesis in highly polluted rivers, suggesting that local environmental constraints, such as environmental pollution caused by human activities, can be stronger than dispersal limitation caused by regional factors to shape local community structure of zooplankton at the basin level. PMID:26912391

  20. The silicate absorption profile in the interstellar medium towards the heavily obscured nucleus of NGC 4418

    NASA Astrophysics Data System (ADS)

    Roche, P. F.; Alonso-Herrero, A.; Gonzalez-Martin, O.

    2015-05-01

    The 9.7-μm silicate absorption profile in the interstellar medium (ISM) provides important information on the physical and chemical composition of interstellar dust grains. Measurements in the Milky Way have shown that the profile in the diffuse ISM is very similar to the amorphous silicate profiles found in circumstellar dust shells around late M stars, and narrower than the silicate profile in denser star-forming regions. Here, we investigate the silicate absorption profile towards the very heavily obscured nucleus of NGC 4418, the galaxy with the deepest known silicate absorption feature, and compare it to the profiles seen in the Milky Way. Comparison between the 8-13 μm spectrum obtained with Thermal-Region Camera Spectrograph on Gemini and the larger aperture spectrum obtained from the Spitzer archive indicates that the former isolates the nuclear emission, while Spitzer detects low surface brightness circumnuclear diffuse emission in addition. The silicate absorption profile towards the nucleus is very similar to that in the diffuse ISM in the Milky Way with no evidence of spectral structure from crystalline silicates or silicon carbide grains.

  1. [Optimizing remediation conditions of non-thermal plasma for DDTs heavily contaminated soil].

    PubMed

    Chen, Hai-Hong; Luo, Yong-Ming; Teng, Ying; Liu, Wu-Xing; Pan, Cheng; Li, Zhen-Gao; Huang, Yu-Juan

    2013-01-01

    A series of experiments were carried out in a non-thermal reactor to remove DDTs in heavily contaminated soil by dielectric barrier discharge (DBD). The study aims to investigate the effects of soil properties (including soil particle size and soil water content) and equipment working parameters (e. g. the plasma power, the processing time and discharge atmosphere) on the removal of DDTs from soil. The results showed that DDTs in soil were significantly degraded by the non-thermal plasma produced by dielectric barrier discharge. Removal rate of DDTs increased with increasing processing time. The removal efficiency of DDTs ranged from 95.3% to 99.9% in 20 minutes. The optimum conditions were as follows: 1 kW of the plasma power, 20 minutes of processing time in air discharge atmosphere, 0-0.9 mm soil particle size and 4.5% -10.5% of soil moisture content. The results also showed that o,p'-DDE might be the intermediate dechlorination and dehydrogenation product of the o,p'-DDT after the oxidization. PMID:23487955

  2. Cathodoluminescence measurements on heavily boron doped homoepitaxial diamond films and their interfaces with their Ib substrates

    NASA Astrophysics Data System (ADS)

    Baron, C.; Deneuville, A.; Wade, M.; Jomard, F.; Chevallier, J.

    2006-02-01

    Heavily boron doped 1.8 to 2.4 μm thick homoepitaxial diamond films with 1.5 × 1021 cm-3 [B] 1.75 × 1021 cm-3 have been deposited directly on their (100) Ib substrates at 830 °C. Their cathodoluminescence spectra probe the controlled thicknesses from 0.28 to 2.8 μm, therefore the bulk of the films as well as their interfaces with their substrates. The bulk of these films exhibit a band with shoulders ascribed to BETO (5.036 eV), FETO (5.094 eV) and BENP (5.184 eV) excitons whose energies are downward shifted by about 180 meV in comparison with monocrystalline diamond with low [B] < 5 × 1018 cm-3. This large shift allows the appearance of narrow peaks around 5.216, 5.271 and 5.357 eV ascribed to BETO, FETO and BENP from interfacial layers with low [B]. From their BETO to FETO ratio, their concentration of boron on isolated substitutional sites is significantly lower than their total low [B] content measured by SIMS. A tentative model is proposed to explain the characteristics of these 40 to 160 quasihomogeneous interfacial layers.

  3. Decreasing the contamination and toxicity of a heavily contaminated soil by in situ bioremediation

    NASA Astrophysics Data System (ADS)

    Groudev, Stoyan; Georgiev, Plamen; Spasova, Irena; Nikolova, Marina

    2013-04-01

    An experimental plot of 140 m2 consisting of acidic soil heavily contaminated with uranium, non-ferrous metals (mainly Cu, Zn and Cd) and arsenic was treated in situ under real field conditions using the activity of the indigenous soil microflora. This activity was enhanced by suitable changes of some essential environmental factors such as pH and water, oxygen and nutrient contents of the soil. The treatment was connected with solubilization and removal of contaminants from the top soil layers (horizon A) due to the joint action of the soil microorganisms (mainly acidophilic chemolithotrophic bacteria) and leach solutions (diluted sulphuric acid). The dissolved contaminants were transferred to the soil horizon B and were removed from the soil profile through a system of drainage collecting pipes. The contaminated soil effluents were treated by means of a multi-component passive system consisting of an anoxic alkalizing drain, a permeable reactive multibarrier and a rock filter. The contamination and toxicity of the soil were regularly tested during the cleaning procedure and were considerably decreased at the end of the treatment.

  4. Effect of packaging atmospheres on storage quality characteristics of heavily marbled beef longissimus steaks.

    PubMed

    Yang, Xiaoyin; Zhang, Yimin; Zhu, Lixian; Han, Mingshan; Gao, Shujuan; Luo, Xin

    2016-07-01

    The objective of this study was to investigate the effects of modified atmosphere packaging (MAP) systems on shelf-life and quality of beef steaks with high marbling. Four packaging types were used including 80% O2 MAP (80% O2+20% CO2), 50% O2 MAP (50% O2+30% CO2+20% N2), carbon monoxide MAP (0.4% CO+30% CO2+69.6% N2) and vacuum packaging (VP). Steaks were displayed under simulated retail conditions at 4°C for 12days. Purge loss, pH, color stability, oxidative stability and microbial counts were monitored. Aerobically packaged steaks exhibited a bright-red color at the first 4days. However, discoloration and oxidation became major factors limiting their shelf-life to 8days. Compared with aerobic packaging, anaerobic packaging extended shelf-life of heavily marbled beef steaks, due to better color stability, together with lower oxidation and microbial populations. Among all packaging methods, CO-MAP had the best preservation for steaks, with more red color than other packaging types. PMID:26946476

  5. Determinants of community structure of zooplankton in heavily polluted river ecosystems

    NASA Astrophysics Data System (ADS)

    Xiong, Wei; Li, Jie; Chen, Yiyong; Shan, Baoqing; Wang, Weimin; Zhan, Aibin

    2016-02-01

    River ecosystems are among the most affected habitats globally by human activities, such as the release of chemical pollutants. However, it remains largely unknown how and to what extent many communities such as zooplankton are affected by these environmental stressors in river ecosystems. Here, we aim to determine major factors responsible for shaping community structure of zooplankton in heavily polluted river ecosystems. Specially, we use rotifers in the Haihe River Basin (HRB) in North China as a case study to test the hypothesis that species sorting (i.e. species are “filtered” by environmental factors and occur at environmental suitable sites) plays a key role in determining community structure at the basin level. Based on an analysis of 94 sites across the plain region of HRB, we found evidence that both local and regional factors could affect rotifer community structure. Interestingly, further analyses indicated that local factors played a more important role in determining community structure. Thus, our results support the species sorting hypothesis in highly polluted rivers, suggesting that local environmental constraints, such as environmental pollution caused by human activities, can be stronger than dispersal limitation caused by regional factors to shape local community structure of zooplankton at the basin level.

  6. Shock-Absorbent Ball-Screw Mechanism

    NASA Technical Reports Server (NTRS)

    Hirr, Otto A., Jr.; Meneely, R. W.

    1986-01-01

    Actuator containing two ball screws in series employs Belleville springs to reduce impact loads, thereby increasing life expectancy. New application of springs increases reliability of equipment in which ball screws commonly used. Set of three springs within lower screw of ball-screw mechanism absorbs impacts that result when parts reach their upper and lower limits of movement. Mechanism designed with Belleville springs as shock-absorbing elements because springs have good energy-to-volume ratio and easily stacked to attain any stiffness and travel.

  7. Coherent perfect absorber based on metamaterials

    NASA Astrophysics Data System (ADS)

    Nie, Guangyu; Shi, Quanchao; Zhu, Zheng; Shi, Jinhui

    2014-11-01

    We demonstrate selective coherent perfect absorption based on interaction between bilayered asymmetrically split rings (ASRs) metamaterials and a standing wave formed by two coherent counter propagating beams. The selective coherent perfect absorbers with high absorption have been achieved depending on the phase difference between two coherent beams. The selective coherent control absorbers can be well designed by changing the thickness of the dielectric layer and the asymmetry of the ASRs. The coherently controlled metamaterials provide an opportunity to realize selective multiband absorption and ultrafast information processing.

  8. OSCEE fan exhaust bulk absorber treatment evaluation

    NASA Technical Reports Server (NTRS)

    Bloomer, H. E.; Samanich, N. E.

    1980-01-01

    The acoustic suppression capability of bulk absorber material designed for use in the fan exhaust duct walls of the quiet clean short haul experiment engine (OCSEE UTW) was evaluated. The acoustic suppression to the original design for the engine fan duct which consisted of phased single degree-of-freedom wall treatment was tested with a splitter and also with the splitter removed. Peak suppression was about as predicted with the bulk absorber configuration, however, the broadband characteristics were not attained. Post test inspection revealed surface oil contamination on the bulk material which could have caused the loss in bandwidth suppression.

  9. SELECTIVE ABSORBER COATED FOILS FOR SOLAR COLLECTORS

    SciTech Connect

    Lampert, Carl M.

    1980-04-01

    Solar absorber metal foils are discussed in terms of materials and basic processing science. Also included is the use of finished heavy sheet stock for direct fabrication of solar collector panels. Both the adhesives and bonding methods for foils and sheet are surveyed. Developmental and representative commercial foils are used as illustrative examples. As a result it was found that foils can compete economically with batch plating but are limited by adhesive temperature stability. Also absorber foils are very versatile and direct collector fabrication from heavy foils appears very promising.

  10. Wavelength-tunable microbolometers with metamaterial absorbers.

    PubMed

    Maier, Thomas; Brückl, Hubert

    2009-10-01

    Microbolometers are modified by metallic resonant absorber elements, leading to an enhanced responsivity at selectable wavelengths. The dissipative energy absorption of tailored metamaterials allows for engineering the response of conventional bolometer microbridges. The absorption peak position and height are determined by the geometry of the metamaterial. Square-shaped metal/dielectric/metal stacks as absorber elements show spectral resonances at wavelengths between 4.8 and 7.0 microm in accordance with numerical simulations. Total peak absorptions of 0.8 are obtained. The metamaterial modified bolometers are suitable for multispectral thermal imaging systems in the mid-IR and terahertz regime. PMID:19794799

  11. Durability of Polymeric Glazing and Absorber Materials

    SciTech Connect

    Jorgensen, G.; Terwilliger, K.; Bingham, C.; Lindquist, C.; Milbourne, M.

    2005-11-01

    The Solar Heating and Lighting Program has set the goal of reducing the cost of solar water heating systems by at least 50%. An attractive approach to such large cost reduction is to replace glass and metal parts with less-expensive, lighter-weight, more-integrated polymeric components. The key challenge with polymers is to maintain performance and assure requisite durability for extended lifetimes. We have begun evaluation of several new UV-screened polycarbonate sheet glazing constructions. This has involved interactions with several major polymer industry companies to obtain improved candidate samples. Proposed absorber materials were tested for UV resistance, and appear adequate for unglazed ICS absorbers.

  12. The MIRD method of estimating absorbed dose

    SciTech Connect

    Weber, D.A.

    1991-01-01

    The estimate of absorbed radiation dose from internal emitters provides the information required to assess the radiation risk associated with the administration of radiopharmaceuticals for medical applications. The MIRD (Medical Internal Radiation Dose) system of dose calculation provides a systematic approach to combining the biologic distribution data and clearance data of radiopharmaceuticals and the physical properties of radionuclides to obtain dose estimates. This tutorial presents a review of the MIRD schema, the derivation of the equations used to calculate absorbed dose, and shows how the MIRD schema can be applied to estimate dose from radiopharmaceuticals used in nuclear medicine.

  13. The Cooling of a Liquid Absorber using a Small Cooler

    SciTech Connect

    Baynham, D.E.; Bradshaw, T.W.; Green, M.A.; Ishimoto, S.; Liggins, N.

    2005-08-24

    This report discusses the use of small cryogenic coolers for cooling the Muon Ionization Cooling Experiment (MICE) liquid cryogen absorbers. Since the absorber must be able contain liquid helium as well liquid hydrogen, the characteristics of the available 4.2 K coolers are used here. The issues associated with connecting two-stage coolers to liquid absorbers are discussed. The projected heat flows into an absorber and the cool-down of the absorbers using the cooler are presented. The warm-up of the absorber is discussed. Special hydrogen safety issues that may result from the use of a cooler on the absorbers are also discussed.

  14. Estimating the radiation absorbed by a human.

    PubMed

    Kenny, Natasha A; Warland, Jon S; Brown, Robert D; Gillespie, Terry G

    2008-07-01

    The complexities of the interactions between long- and short-wave radiation fluxes and the human body make it inherently difficult to estimate precisely the total radiation absorbed (R) by a human in an outdoor environment. The purpose of this project was to assess and compare three methods to estimate the radiation absorbed by a human in an outdoor environment, and to compare the impact of applying various skin and clothing albedos (alpha ( h )) on R. Field tests were conducted under both clear and overcast skies to evaluate the performance of applying a cylindrical radiation thermometer (CRT), net radiometer, and a theoretical estimation model to predict R. Three albedos were evaluated: light (alpha ( h ) = 0.57), medium (alpha ( h ) = 0.37), and dark (alpha ( h ) = 0.21). During the sampling periods, the range of error between the methods used to estimate the radiation absorbed by a cylindrical body under clear and overcast skies ranged from 3 to 8%. Clothing and skin albedo had a substantial impact on R, with the mean change in R between the darkest and lightest albedos ranging from 115 to 157 W m( - 2) over the sampling period. Radiation is one of the most important variables to consider in outdoor thermal comfort research, as R is often the largest contributor to the human energy balance equation. The methods outlined and assessed in this study can be conveniently applied to provide reliable estimates of the radiation absorbed by a human in an outdoor environment. PMID:18273649

  15. Optimization of ramified absorber networks doing desalination.

    PubMed

    Singleton, Martin S; Heiss, Gregor; Hübler, Alfred

    2011-01-01

    An iterated function system is used to generate fractal-like ramified graph networks of absorbers, which are optimized for desalination performance. The diffusion equation is solved for the boundary case of constant pressure difference at the absorbers and a constant ambient salt concentration far from the absorbers, while constraining both the total length of the network and the total area of the absorbers to be constant as functions of generation G. A linearized form of the solution was put in dimensionless form which depends only on a dimensionless membrane resistance, a dimensionless inverse svelteness ratio, and G. For each of the first nine generations G=2,…,10, the optimal graph shapes were obtained. Total water production rate increases parabolically as a function of generation, with a maximum at G=7. Total water production rate is shown to be approximately linearly related to the power consumed, for a fixed generation. Branching ratios which are optimal for desalination asymptote decreasingly to r=0.510 for large G, while branching angles which are optimal for desalination asymptote decreasingly to 1.17 radians. Asymmetric graphs were found to be less efficient for desalination than symmetric graphs. The geometry which is optimal for desalination does not depend strongly on the dimensionless parameters, but the optimal water production does. The optimal generation was found to increase with the inverse svelteness ratio. PMID:21405775

  16. Aldehyde-containing urea-absorbing polysaccharides

    NASA Technical Reports Server (NTRS)

    Mueller, W. A.; Hsu, G. C.; Marsh, H. E., Jr. (Inventor)

    1977-01-01

    A novel aldehyde containing polymer (ACP) is prepared by reaction of a polysaccharide with periodate to introduce aldehyde groups onto the C2 - C3 carbon atoms. By introduction of ether and ester groups onto the pendant primary hydroxyl solubility characteristics are modified. The ACP is utilized to absorb nitrogen bases such as urea in vitro or in vivo.

  17. Shock absorbing mount for electrical components

    NASA Technical Reports Server (NTRS)

    Dillon, R. F., Jr.; Mayne, R. C. (Inventor)

    1975-01-01

    A shock mount for installing electrical components on circuit boards is described. The shock absorber is made of viscoelastic material which interconnects the electrical components. With this system, shocks imposed on one component of the circuit are not transmitted to other components. A diagram of a typical circuit is provided.

  18. Tunable metamaterial dual-band terahertz absorber

    NASA Astrophysics Data System (ADS)

    Luo, C. Y.; Li, Z. Z.; Guo, Z. H.; Yue, J.; Luo, Q.; Yao, G.; Ji, J.; Rao, Y. K.; Li, R. K.; Li, D.; Wang, H. X.; Yao, J. Q.; Ling, F. R.

    2015-11-01

    We report a design of a temperature controlled tunable dual band terahertz absorber. The compact single unit cell consists of two nested closed square ring resonators and a layer metallic separated by a substrate strontium titanate (STO) dielectric layer. It is found that the absorber has two distinctive absorption peaks at frequencies 0.096 THz and 0.137 THz, whose peaks are attained 97% and 75%. Cooling the absorber from 400 K to 250 K causes about 25% and 27% shift compared to the resonance frequency of room temperature, when we cooling the temperature to 150 K, we could attained both the two tunabilities exceeding 53%. The frequency tunability is owing to the variation of the dielectric constant of the low-temperature co-fired ceramic (LTCC) substrate. The mechanism of the dual band absorber is attributed to the overlapping of dual resonance frequencies, and could be demonstrated by the distributions of the electric field. The method opens up avenues for designing tunable terahertz devices in detection, imaging, and stealth technology.

  19. Moving core beam energy absorber and converter

    DOEpatents

    Degtiarenko, Pavel V.

    2012-12-18

    A method and apparatus for the prevention of overheating of laser or particle beam impact zones through the use of a moving-in-the-coolant-flow arrangement for the energy absorbing core of the device. Moving of the core spreads the energy deposition in it in 1, 2, or 3 dimensions, thus increasing the effective cooling area of the device.

  20. Composition for absorbing hydrogen from gas mixtures

    DOEpatents

    Heung, Leung K.; Wicks, George G.; Lee, Myung W.

    1999-01-01

    A hydrogen storage composition is provided which defines a physical sol-gel matrix having an average pore size of less than 3.5 angstroms which effectively excludes gaseous metal hydride poisons while permitting hydrogen gas to enter. The composition is useful for separating hydrogen gas from diverse gas streams which may have contaminants that would otherwise render the hydrogen absorbing material inactive.

  1. Heat loss through the glabrous skin surfaces of heavily insulated, heat-stressed individuals.

    PubMed

    Grahn, D A; Dillon, J L; Heller, H C

    2009-07-01

    Insulation reduces heat exchange between a body and the environment. Glabrous (nonhairy) skin surfaces (palms of the hands, soles of the feet, face, and ears) constitute a small percentage of total body surface area but contain specialized vascular structures that facilitate heat loss. We have previously reported that cooling the glabrous skin surfaces is effective in alleviating heat stress and that the application of local subatmospheric pressure enhances the effect. In this paper, we compare the effects of cooling multiple glabrous skin surfaces with and without vacuum on thermal recovery in heavily insulated heat-stressed individuals. Esophageal temperatures (T(es)) and heart rates were monitored throughout the trials. Water loss was determined from pre- and post-trial nude weights. Treadmill exercise (5.6 km/h, 9-16% slope, and 25-45 min duration) in a hot environment (41.5 degrees C, 20-30% relative humidity) while wearing insulating pants and jackets was used to induce heat stress (T(es)>or=39 degrees C). For postexercise recovery, the subjects donned additional insulation (a balaclava, winter gloves, and impermeable boot covers) and rested in the hot environment for 60 min. Postexercise cooling treatments included control (no cooling) or the application of a 10 degrees C closed water circulating system to (a) the hand(s) with or without application of a local subatmospheric pressure, (b) the face, (c) the feet, or (d) multiple glabrous skin regions. Following exercise induction of heat stress in heavily insulated subjects, the rate of recovery of T(es) was 0.4+/-0.2 degrees C/h(n=12), but with application of cooling to one hand, the rate was 0.8+/-0.3 degrees C/h(n=12), and with one hand cooling with subatmospheric pressure, the rate was 1.0+/-0.2 degrees C/h(n=12). Cooling alone yielded two responses, one resembling that of cooling with subatmospheric pressure (n=8) and one resembling that of no cooling (n=4). The effect of treating multiple surfaces was

  2. Fifth Graders' Enjoyment, Interest, and Comprehension of Graphic Novels Compared to Heavily-Illustrated and Traditional Novels

    ERIC Educational Resources Information Center

    Jennings, Kimberly Ann; Rule, Audrey C.; Vander Zanden, Sarah M.

    2014-01-01

    The comparative effectiveness of graphic novels, heavily illustrated novels, and traditional novels as reading teaching tools has been sparsely researched. During the 2011-2012 school year, 24 mixed-ability fifth grade students chose to read six novels: two traditional novels, two highly illustrated novels and two graphic novels. Students…

  3. Biomonitoring of polychlorinated biphenyls (PCBs) in heavily polluted aquatic environment in different fish species.

    PubMed

    Brázová, Tímea; Hanzelová, Vladimíra; Miklisová, Dana; Šalgovičová, Danka; Turčeková, L'udmila

    2012-11-01

    The distribution and concentrations of polychlorinated biphenyls (PCBs) were determined in fish species (European perch Perca fluviatilis, northern pike Esox lucius, pike perch Sander lucioperca, wels catfish Silirus glanus, common carp Cyprinus carpio, European eel Anguilla anguilla, freshwater bream Abramis brama, goldfish Carassius auratus, and roach Rutilus rutilus) in a heavily polluted water reservoir Zemplínska šírava (Slovakia). The study performed at two different time points 5 years apart (2004 and 2009) revealed serious PCB contamination of fish muscle tissue and significant interspecies as well as tissue-specific differences in PCB uptake by fish. Total PCBs broadly correlated with the trophic position of individual fish species within a food chain (P < 0.01). The concentrations were particularly high in predatory fish species, perch, pike, and pike perch (108.0, 90.1, and 113.0 mg kg(-1) lipid wt, respectively), but comparable PCB values were also found in non-predatory detrivorous freshwater bream (128.0 mg kg(-1) lipid wt). The lowest PCB values were surprisingly assessed in European eel (17.1 mg kg(-1) lipid wt). Tissue analysis showed the highest storage capacity of the liver (hepatopancreas in cyprinids) with maximum concentrations recorded found in northern pike (214.0 mg kg(-1) lipid wt) and freshwater bream (163.0 mg kg(-1) lipid wt). Negative correlations, mostly not significant, between the total PCB concentrations and fish weight were observed (P > 0.05). The study has shown that the kind of fish, its feeding habit, and specific conditions of the habitat are mutually interrelated factors that are responsible for significant variations in fish body burdens. A tendency to PCB biomagnification was also proved in some fish species of this water reservoir. PMID:22173787

  4. Incidence and clinical significance of ESR1 mutations in heavily pretreated metastatic breast cancer patients

    PubMed Central

    Niu, Jiaxin; Andres, Grant; Kramer, Kim; Kundranda, Madappa N; Alvarez, Ricardo H; Klimant, Eiko; Parikh, Ankur R; Tan, Bradford; Staren, Edgar D; Markman, Maurie

    2015-01-01

    Background ESR1 mutation has recently emerged as one of the important mechanisms involved in endocrine resistance. The incidence and clinical implication of ESR1 mutation has not been well evaluated in heavily pretreated breast cancer patients. Methods We conducted a retrospective review of advanced breast cancer patients with tumors who underwent next-generation sequencing genomic profiling using Foundation One test at Cancer Treatment Centers of America® regional hospitals between November 2012 and November 2014. Results We identified a total of 341 patients including 217 (59%) estrogen receptor (ER)+, 177 (48%) progesterone receptor (PR)+, 30 (8%) hormone receptor+/HER2 positive, and 119 (32%) triple negative patients. ESR1 mutation was noted in 27/222 (12.1%) ER+ or PR+ breast cancer patients. All ER+ patients received at least one line of an aromatase inhibitor. All 28 patients were found to harbor ESR1 mutations affecting ligand-binding domain with the most common mutations affecting Y537 (17/28, 60.7%) and D538 (9/28, 32.1%). In this cohort, 19 (67.9%) patients carried three or more, seven (25%) patients had one or two additional genomic alterations and one (3.6%) patient had an ESR1 mutation only. Of 28 patients, three patients were treated with fulvestrant immediately before and two patients were treated after next-generation sequencing testing; only one patient achieved stable disease for 8 months and the other four patients had progression of disease. In all, 3/3 (100%) patients before testing and 2/4 (50%) after testing treated with exemestane and everolimus achieved stable disease for at least 6 months. Conclusion ESR1 mutation was found in 12.1% of a large cohort of advanced breast cancer patients. Exemestane in combination with everolimus might be a reasonable option. Prospective studies are warranted to validate these findings. PMID:26648736

  5. Computation of backwater and discharge at width constrictions of heavily vegetated flood plains

    USGS Publications Warehouse

    Schneider, V.R.; Board, J.W.; Colson, B.E.; Lee, F.N.; Druffel, Leroy

    1977-01-01

    The U.S. Geological Survey, cooperated with the Federal Highway Administration and the State Highway Departments of Mississippi, Alabama, and Louisiana, to develop a proposed method for computing backwater and discharge at width constrictions of heavily vegetated flood plains. Data were collected at 20 single opening sites for 31 floods. Flood-plain width varied from 4 to 14 times the bridge opening width. The recurrence intervals of peak discharge ranged from a 2-year flood to greater than a 100-year flood, with a median interval of 6 years. Measured backwater ranged from 0.39 to 3.16 feet. Backwater computed by the present standard Geological Survey method averaged 29 percent less than the measured, and that computed by the currently used Federal Highway Administration method averaged 47 percent less than the measured. Discharge computed by the Survey method averaged 21 percent more then the measured. Analysis of data showed that the flood-plain widths and the Manning 's roughness coefficient are larger than those used to develop the standard methods. A method to more accurately compute backwater and discharge was developed. The difference between the contracted and natural water-surface profiles computed using standard step-backwater procedures is defined as backwater. The energy loss terms in the step-backwater procedure are computed as the product of the geometric mean of the energy slopes and the flow distance in the reach was derived from potential flow theory. The mean error was 1 percent when using the proposed method for computing backwater and 3 percent for computing discharge. (Woodard-USGS)

  6. The electron spin resonance study of heavily nitrogen doped 6H SiC crystals

    SciTech Connect

    Savchenko, D. V.

    2015-01-28

    The magnetic and electronic properties of heavily doped n-type 6H SiC samples with a nitrogen concentration of 10{sup 19} and 4 × 10{sup 19 }cm{sup −3} were studied with electron spin resonance (ESR) at 5–150 K. The observed ESR line with a Dysonian lineshape was attributed to the conduction electrons (CE). The CE ESR (CESR) line was fitted by Lorentzian (insulating phase) (T < 40 K) and by Dysonian lineshape (metallic phase) above 40 K, demonstrating that Mott insulator-metal (IM) transition takes place at ∼40 K, accompanied by significant change in the microwave conductivity. The temperature dependence of CESR linewidth follows the linear Korringa law below 40 K, caused by the coupling of the localized electrons (LE) and CE, and is described by the exponential law above 40 K related to the direct relaxation of the LE magnetic moments via excited levels driven by the exchange interaction of LE with CE. The g-factor of the CESR line (g{sub ‖} = 2.0047(3), g{sub ⊥} = 2.0034(3)) is governed by the coupling of the LE of nitrogen donors at hexagonal and quasi-cubic sites with the CE. The sharp drop in CESR line intensity (25–30 K) was explained by the formation of antiferromagnetic ordering in the spin system close to the IM transition. The second broad ESR line overlapped with CESR signal (5–25 K) was attributed to the exchange line caused by the hopping motion of electrons between occupied and non-occupied positions of the nitrogen donors. Two mechanisms of conduction, hopping and band conduction, were distinguished in the range of T = 10–25 K and T > 50 K, respectively.

  7. A Multidisciplinary Assessment of River Surface Water Quality in Areas Heavily Influenced by Human Activities.

    PubMed

    Charalampous, Nikolina; Kindou, Aggeliki; Vlastos, Dimitris; Tsarpali, Vasiliki; Antonopoulou, Maria; Konstantinou, Ioannis; Dailianis, Stefanos

    2015-08-01

    The present study could serve as a multidisciplinary approach for the assessment of river surface water quality with the use of chemical and biological methods. Specifically, physicochemical parameters, heavy metals, and pesticides were measured in water samples from three different stations (sampling station S1, S2, and S3) along Asopos River (Greece). In parallel, algal species (primary producers)-such as Scenedesmus rubescens and Chlorococcum sp.; consumer invertebrate species, such as the fairy shrimp Thamnocephalus platyurus and the rotifer Brachionus calyciflorus; as well as human lymphocytes-were exposed to those samples for assessing their toxic and genotoxic/mutagenic effects. According to the results, although the values of almost all of the physicochemical parameters tested, heavy metals (zinc, cadmium, lead, and mercury) and pesticides were lower than or within the respective environmental quality standards, thus offering no clear evidence for their natural or anthropogenic origin. Values recorded for nickel, chromium, hexavalent chromium, and malathion represent a typical case of mixed influence from natural and anthropogenic enrichments. In contrast, the algal growth arrest, the acute toxic effects on the freshwater invertebrates, and the increased micronuclei frequencies observed in human lymphocytes showed the presence of human-derived hazardous substances, which were hardly determinable with the use of conventional chemical methods. Given that the presence of priority pollutants in river surface waters, heavily burdened by anthropogenic activities, could give no clear evidence for their biological risk, the results of the present study showed that chemical and biological assays should be applied in parallel, thus serving as a reliable tool for the assessment of river water quality. PMID:25832760

  8. Energy-gap reduction in heavily doped silicon: Causes and consequences

    NASA Astrophysics Data System (ADS)

    Pantelides, Sokrates T.; Selloni, Annabella; Car, Roberto

    1985-02-01

    The authors review briefly the existing theoretical treatments of the various effects that contribute to the reduction of the energy gap in heavily doped Si, namely electron-electron and electron-impurity interactions and the effect of disorder in the impurity distribution. They then turn to the longstanding question why energy-gap reductions extracted from three different types of experiments have persistently produced values with substantial discrepancies, making it impossible to compare with theoretical values. First, they demonstrate that a meaningful comparison between theory and experiment can indeed be made if theoretical calculations are carried out for actual quantities that experiments measure, e.g. luminescence spectra, as recently done by Selloni and Pantelides. Then, they demonstrate that, independent of any theoretical calculations, the optical absorption spectra are fully consistent with the luminescence spectra and that the discrepancies in the energy-gap reductions extracted from the two sets of spectra are caused entirely by the curve-fitting procedures used in analyzing optical-absorption data. Finally, they show explicitly that, as already believed by many authors, energy-gap reductions extracted from electrical measurements on transistors do not correspond to true gap reductions. They identify two corrections that must be added to the values extracted from the electrical data in order to arrive at the true gap reductions and show that the resulting values are in good overall agreement with luminescence and absorption data. They, therefore, demonstrate that the observed reduction in emitter injection efficiency in bipolar transistors is not strictly due to a gap reduction, as generally believed, but to three very different effects.

  9. Shallow melting of thin heavily doped silicon layers by pulsed CO/sub 2/ laser irradiation

    SciTech Connect

    James, R.B.; Christie, W.H.

    1989-05-01

    We show that an extremely shallow (approx. <800 A) melt depth can be easily obtained by irradiating a thin (/similar to/200 A) heavily doped silicon layer with a CO/sub 2/ laser pulse. Since the absorption of the CO/sub 2/ laser pulse is dominated by free-carrier transitions, the beam heating occurs primarily in the thin degenerately doped film at the sample surface, and there is little energy deposited in the underlying lightly doped substrate. For CO/sub 2/ pulse-energy densities exceeding a threshold value of about 5 J/cm/sup 2/, surface melting occurs and the reflectivity of the incident laser pulse increases abruptly to about 90%. This large increase in the reflectivity acts like a switch to reflect almost all of the energy in the remainder of the CO/sub 2/ laser pulse, thereby greatly reducing the amount of energy available to drive the melt front to deeper depths in the material. This is in contrast to the energy deposition of a laser pulse that has a photon energy exceeding the band gap, in which case the penetration depth of the incident radiation is only weakly affected by the free-carrier density. Transmission electron microscopy shows no extended defects in the near-surface region after CO/sub 2/ laser irradiation, and van der Pauw electrical measurements verify that 100% of the implanted arsenic dopant is electrically active. Calculated values for the melt depth versus incident pulse-energy density (E/sub L/) indicate that there exists a window where the maximum melt-front penetration increases slowly with increasing E/sub L/ and has a value of less than a few hundred angstroms.

  10. Transitory O-rich chemistry in heavily obscured C-rich post-AGB stars

    NASA Astrophysics Data System (ADS)

    García-Hernández, D. A.; García-Lario, P.; Cernicharo, J.; Engels, D.; Perea-Calderón, J. V.

    2016-07-01

    Spitzer/IRS spectra of eleven heavily obscured C-rich sources rapidly evolving from asymptotic giant branch (AGB) stars to Planetary Nebulae are presented. IRAM 30m observations for three of these post-AGBs are also reported. A few (3) of these sources are known to exhibit strongly variable maser emission of O-bearing molecules such as OH and H2 O, suggesting a transitory O-rich chemistry because of the quickly changing physical and chemical conditions in this short evolutionary phase. Interestingly, the Spitzer/IRS spectra show a rich circumstellar carbon chemistry, as revealed by the detection of small hydrocarbon molecules such as C2H2, C4H2, C6H2, C6H6, and HCN. Benzene is detected towards two sources, bringing up to three the total number of Galactic post-AGBs where this molecule has been detected. In addition, we report evidence for the possible detection of other hydrocarbon molecules like HC3N, CH3C2H, and CH3 in several of these sources. The available IRAM 30m data confirm that the central stars are C-rich - in despite of the presence of O-rich masers - and the presence of high velocity molecular outflows together with extreme AGB mass-loss rates (∼⃒10-4 Mʘ /yr). Our observations confirm the polymerization model of Cernicharo [1] that predicts a rich photochemistry in the neutral regions of these objects on timescales shorter than the dynamical evolution of the central HII region, leading to the formation of small C-rich molecules and a transitory O-rich chemistry.

  11. Stock, turnover and functions of carbon in heavily weathered soils under lowland rainforest transformation systems

    NASA Astrophysics Data System (ADS)

    Guillaume, Thomas; Kuzyakov, Yakov

    2013-04-01

    Tropical rainforest are experiencing worldwide a strong lost through deforestation and transformation into agricultural systems. Land use changes in such ecosystems leads to major modifications of soils properties and processes. One indication of it are the losses of organic carbon content (Corg); an important soil fertility parameter in heavily weathered soil. Between 1985 and 2007, Sumatra (Indonesia) has lost half of his remaining natural rainforest, which currently covers only 30% the island. The deforestation is still ongoing and the main drivers of deforestation are oil palm, rubber and timber industries. Our study aims to identify and quantify the impacts of lowland rainforest transformation systems (TS): oil palm, rubber and jungle rubber plantations on soil organic carbon (SOC) and nitrogen (SON) quality, turnover and stocks and so, on soil fertility and functions. We hypothesize that transformation of natural lowland rainforest changes not only C stock and budget throughout quantity and quality of C input, but also DOM production and water consumption by vegetation, leading to a relocation of C in the subsoil. This should be reflected in C and N content in soil profile horizons as well as their δ13C and δ15N isotopic signatures. We will evaluate also C stability through biological, thermal and chemical stability in bulk soil and aggregate fractions. The TS investigated, including lowland rainforest as reference sites, are located in Jambi Province (Sumatra). Soil has been described and sampled per horizon on 4 replicates of each TS in 2 different regions (32 sites) in Autumn 2012. As hypothesized, first results show strong effects of forest transformation on C and N content, as well as on isotopic signatures of soil. Those results will also be used further to select DOM sampling depths and adequate horizons to perform sorption and incubation experiments.

  12. Transradial versus transfemoral rotablation for heavily calcified coronary lesions in contemporary drug-eluting stent era

    PubMed Central

    Yin, Wei-Hsian; Tseng, Chin-Kun; Tsao, Tien-Ping; Jen, Hsu-Lung; Huang, Wen-Pin; Huang, Chien-Lung; Wang, Jiann-Jong; Young, Mason Shing

    2015-01-01

    Background Although radial access for drug-eluting stent (DES) combined with rotational atherectomy (RA) in patients with calcified coronary lesions may be associated with a lower risk of major bleeding complications and obtain favorable clinical results compared with femoral access, the long-term outcome data of this approach were limited in contemporary DES era. Methods & Results This retrospective study sought to compare in-hospital and long-term outcomes for patients undergoing RA via the transradial (TR) and transfemoral (TF) route in 126 consecutive patients (59 radial, 67 femoral) from 2009 to 2014. TR RA procedures were performed in 44/62 (71%) by the three TR operators, compared with 15/64 (23%) by the four TF operators in the present study. Significantly smaller diameter guide catheters and burrs (1.39 ± 0.16 mm vs. 1.53 ± 0.24 mm, P = 0.001) were used in the TR group. Procedural success rates were similar in both TR and TF groups. There was a significantly less major access site bleeding complications in favor of radial artery access (2% vs. 16%, P = 0.012). The incidence of in-hospital death or myocardial infarction was low in both groups. Although a trend of lower adverse event rate was demonstrated in the TR group compared with the TF one, no statistical significance (21% vs. 27%, P = 0.135) was detected. Conclusions Radial access, a useful alternative to femoral access for RA and DES, can be safely and successfully performed on up to 71% of the patients with heavily calcified coronary lesions needing RA by experienced TR operators. PMID:26512239

  13. Neutron absorbers and methods of forming at least a portion of a neutron absorber

    SciTech Connect

    Guillen, Donna P; Porter, Douglas L; Swank, W David; Erickson, Arnold W

    2014-12-02

    Methods of forming at least a portion of a neutron absorber include combining a first material and a second material to form a compound, reducing the compound into a plurality of particles, mixing the plurality of particles with a third material, and pressing the mixture of the plurality of particles and the third material. One or more components of neutron absorbers may be formed by such methods. Neutron absorbers may include a composite material including an intermetallic compound comprising hafnium aluminide and a matrix material comprising pure aluminum.

  14. Design of a non-traditional dynamic vibration absorber.

    PubMed

    Cheung, Y L; Wong, W O

    2009-08-01

    A non-traditional dynamic vibration absorber is proposed for the minimization of maximum vibration velocity response of a vibrating structure. Unlike the traditional damped absorber configuration, the proposed absorber has a linear viscous damper connecting the absorber mass directly to the ground instead of the main mass. Optimum parameters of the proposed absorber are derived based on the fixed-point theory for minimizing the maximum vibration velocity response of a single-degree-of-freedom system under harmonic excitation. The extent of reduction in maximum vibration velocity response of the primary system when using the traditional dynamic absorber is compared with that using the proposed one. Under the optimum tuning condition of the absorbers, it is proved analytically that the proposed absorber provides a greater reduction in maximum vibration velocity response of the primary system than the traditional absorber. PMID:19640019

  15. Rubber shock absorber for deep-well rod operated pumps

    SciTech Connect

    Bagirov, M.M.

    1984-05-01

    Tests of hydropneumatic shock absorbers of deep-well pumps in oil fields showed that they improve the efficiency of the installations by their design is very complicated. Mechanically acting absorbers of dynamic forces are simpler in design. Rubber shock absorbers differ advantageously from spring absorbers in that considerable oscillation-damping forces of any amplitude act in them. The design of a shock absorber is described which is situated under the balance arm of a pumping jack. A prototype of the shock absorber, in which the elastic elements were cylinders made of rubber was tested in a test borehole. Dynamographic recordings made in this borehole in operation with and without shock absorber show that the shock absorber reduces the maximum load on the rods and the double amplitude of load change. Calculations show that when the described shock absorber is used the reduced load is 11-18% smaller. This may considerably reduce the number of breakages of deepwell pump rods.

  16. GEMINI/GeMS Observations Unveil the Structure of the Heavily Obscured Globular Cluster Liller 1.

    NASA Astrophysics Data System (ADS)

    Saracino, S.; Dalessandro, E.; Ferraro, F. R.; Lanzoni, B.; Geisler, D.; Mauro, F.; Villanova, S.; Moni Bidin, C.; Miocchi, P.; Massari, D.

    2015-06-01

    By exploiting the exceptional high-resolution capabilities of the near-IR camera GSAOI combined with the Gemini Multi-Conjugate Adaptive System at the GEMINI South Telescope, we investigated the structural and physical properties of the heavily obscured globular cluster Liller 1 in the Galactic bulge. We have obtained the deepest and most accurate color–magnitude diagram published so far for this cluster, reaching {{K}s}∼ 19 (below the main-sequence turnoff level). We used these data to redetermine the center of gravity of the system, finding that it is located about 2.″2 southeast from the literature value. We also built new star density and surface brightness profiles for the cluster and rederived its main structural and physical parameters (scale radii, concentration parameter, central mass density, total mass). We find that Liller 1 is significantly less concentrated (concentration parameter c=1.74) and less extended (tidal radius {{r}t}=298\\prime\\prime and core radius {{r}c}=5\\buildrel{\\prime\\prime}\\over{.} 39) than previously thought. By using these newly determined structural parameters, we estimated the mass of Liller 1 to be {{M}tot}=2.3+0.3-0.1× {{10}6} {{M}ȯ } ({{M}tot}=1.5+0.2-0.1× {{10}6} {{M}ȯ } for a Kroupa initial mass function), which is comparable to that of the most massive clusters in the Galaxy (ω Centari and Terzan 5). Also, Liller 1 has the second-highest collision rate (after Terzan 5) among all star clusters in the Galaxy, thus confirming that it is an ideal environment for the formation of collisional objects (such as millisecond pulsars). Based on observations obtained at the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (United States), the National Research Council (Canada), CONICYT (Chile), the Australian Research Council (Australia), Ministério da

  17. GEMINI/GeMS Observations Unveil the Structure of the Heavily Obscured Globular Cluster Liller 1.

    NASA Astrophysics Data System (ADS)

    Saracino, S.; Dalessandro, E.; Ferraro, F. R.; Lanzoni, B.; Geisler, D.; Mauro, F.; Villanova, S.; Moni Bidin, C.; Miocchi, P.; Massari, D.

    2015-06-01

    By exploiting the exceptional high-resolution capabilities of the near-IR camera GSAOI combined with the Gemini Multi-Conjugate Adaptive System at the GEMINI South Telescope, we investigated the structural and physical properties of the heavily obscured globular cluster Liller 1 in the Galactic bulge. We have obtained the deepest and most accurate color-magnitude diagram published so far for this cluster, reaching {{K}s}˜ 19 (below the main-sequence turnoff level). We used these data to redetermine the center of gravity of the system, finding that it is located about 2.″2 southeast from the literature value. We also built new star density and surface brightness profiles for the cluster and rederived its main structural and physical parameters (scale radii, concentration parameter, central mass density, total mass). We find that Liller 1 is significantly less concentrated (concentration parameter c=1.74) and less extended (tidal radius {{r}t}=298\\prime\\prime and core radius {{r}c}=5\\buildrel{\\prime\\prime}\\over{.} 39) than previously thought. By using these newly determined structural parameters, we estimated the mass of Liller 1 to be {{M}tot}=2.3+0.3-0.1× {{10}6} {{M}⊙ } ({{M}tot}=1.5+0.2-0.1× {{10}6} {{M}⊙ } for a Kroupa initial mass function), which is comparable to that of the most massive clusters in the Galaxy (ω Centari and Terzan 5). Also, Liller 1 has the second-highest collision rate (after Terzan 5) among all star clusters in the Galaxy, thus confirming that it is an ideal environment for the formation of collisional objects (such as millisecond pulsars). Based on observations obtained at the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (United States), the National Research Council (Canada), CONICYT (Chile), the Australian Research Council (Australia), Ministério da

  18. Hematological and hepatic alterations in Brazilian population heavily exposed to organochlorine pesticides.

    PubMed

    Freire, Carmen; Koifman, Rosalina Jorge; Koifman, Sergio

    2015-01-01

    The aim of this study was to investigate the frequency of hematological and hepatic alterations and possible association with serum levels of beta-hexachlorocyclohexane (beta-HCH), p,p'-DDE, and hexachlorobenzene (HCB) among residents in an area heavily contaminated with organochlorine (OC) pesticides. A cross-sectional study was conducted in 415 male and 432 female residents aged >14 years. Serum samples were collected and analyzed for OC pesticides concentrations and biochemical parameters. Frequencies of hematological and hepatic alterations were calculated for each gender. Association between beta-HCH, p,p'-DDE (1,1-dichloro-2,2-bis(p-chlorophenyl) ethylene), and HCB levels and presence of alterations was determined by logistic regression stratified by gender and controlling for confounders. Highest frequencies were observed for eosinophilia (23% men and 18% women), low hemoglobin (12% men and 15% women), and low erythrocyte count (12% men). High levels of bilirubin, glutamic-oxaloacetic transaminase (GOT), and glutamic-pyruvic transaminase (GPT) were observed, respectively, in 10, 11, and 12% of men and <10% of women. Gamma-glutamyl transferase (GGT) was elevated in 26 and 25% of males and females, respectively. Multivariate analysis revealed associations between eosinophilia and beta-HCH in men (OR = 1.06, 95%CI = 1.01-1.12) and women (OR = 1.05, 96%CI = 0.99-1.11), p,p'-DDE in men (OR = 1.03, 95%CI = 0.99-1.06) and women (OR = 1.02, 95%CI = 0.99-1.06), and HCB in women (OR = 1.54, 95%IC = 0.85-4.45). Beta-HCH was found to be associated with increased risk of elevated bilirubin in females (OR = 1.18, 95%CI = 1.07-1.29) and males (OR = 4.21, 95%CI = 1.87-9.47 for fourth vs. first quintile). Thus, OC pesticides may exert adverse effects on hematopoietic tissue and liver in populations chronically exposed to high levels of these compounds. PMID:25849770

  19. Fault Detection for Automotive Shock Absorber

    NASA Astrophysics Data System (ADS)

    Hernandez-Alcantara, Diana; Morales-Menendez, Ruben; Amezquita-Brooks, Luis

    2015-11-01

    Fault detection for automotive semi-active shock absorbers is a challenge due to the non-linear dynamics and the strong influence of the disturbances such as the road profile. First obstacle for this task, is the modeling of the fault, which has been shown to be of multiplicative nature. Many of the most widespread fault detection schemes consider additive faults. Two model-based fault algorithms for semiactive shock absorber are compared: an observer-based approach and a parameter identification approach. The performance of these schemes is validated and compared using a commercial vehicle model that was experimentally validated. Early results shows that a parameter identification approach is more accurate, whereas an observer-based approach is less sensible to parametric uncertainty.

  20. Mechanically stretchable and tunable metamaterial absorber

    NASA Astrophysics Data System (ADS)

    Zhang, Fuli; Feng, Shuqi; Qiu, Kepeng; Liu, Zijun; Fan, Yuancheng; Zhang, Weihong; Zhao, Qian; Zhou, Ji

    2015-03-01

    In this letter, we present experimental demonstration of a mechanically stretchable and tunable metamaterial absorber composed of dielectric resonator stacked on a thin conductive rubber layer. A near unity absorption is observed due to strong local field confinement around magnetic Mie resonance of dielectric resonator. Furthermore, the interspacing between unit cells is modulated dynamically under uniaxial stress. Owing to the decreases of longitudinal coupling between neighboring unit cells, the resonant absorption peak is reversibly tuned by 410 MHz, as the stain varies up to 180% along H field direction. On the contrary, the resonant absorption state is nearly independent on strain variation when external stress is applied along E field direction, due to the weak transverse interplaying. The mechanically tunable metamaterial absorber featured by flexibility paves a way forwards for actual application.

  1. Vibration absorber modeling for handheld machine tool

    NASA Astrophysics Data System (ADS)

    Abdullah, Mohd Azman; Mustafa, Mohd Muhyiddin; Jamil, Jazli Firdaus; Salim, Mohd Azli; Ramli, Faiz Redza

    2015-05-01

    Handheld machine tools produce continuous vibration to the users during operation. This vibration causes harmful effects to the health of users for repeated operations in a long period of time. In this paper, a dynamic vibration absorber (DVA) is designed and modeled to reduce the vibration generated by the handheld machine tool. Several designs and models of vibration absorbers with various stiffness properties are simulated, tested and optimized in order to diminish the vibration. Ordinary differential equation is used to derive and formulate the vibration phenomena in the machine tool with and without the DVA. The final transfer function of the DVA is later analyzed using commercial available mathematical software. The DVA with optimum properties of mass and stiffness is developed and applied on the actual handheld machine tool. The performance of the DVA is experimentally tested and validated by the final result of vibration reduction.

  2. Investigations on Absorber Materials at Cryogenic Temperatures

    SciTech Connect

    Marhauser, Frank; Elliott, Thomas; Rimmer, Robert

    2009-05-01

    In the framework of the 12 GeV upgrade project for the Continuous Electron Beam Accelerator Facility (CEBAF) improvements are being made to refurbish cryomodules housing Thomas Jefferson National Accelerator Facility's (JLab) original 5-cell cavities. Recently we have started to look into a possible simplification of the existing Higher Order Mode (HOM) absorber design combined with the aim to find alternative material candidates. The absorbers are implemented in two HOM-waveguides immersed in the helium bath and operate at 2 K temperature. We have built a cryogenic setup to perform measurements on sample load materials to investigate their lossy characteristics and variations from room temperature down to 2 K. Initial results are presented in this paper.

  3. Disposable Diaper Absorbency: Improvements via Advanced Designs.

    PubMed

    Helmes, C Tucker; O'Connor, Robert; Sawyer, Larry; Young, Sharon

    2014-06-24

    Absorbency effectiveness in diapers has improved significantly in recent years with the advent of new ingredient combinations and advanced design features. With these features, many leading products maintain their dryness performance overnight. Considering the importance of holding liquid away from the skin, ongoing research in diaper construction focuses on strategies to increase the effectiveness to capture liquid and help avoid rewetting of infant skin. The layout and design of a disposable diaper allows for distribution of absorbency features where they can provide the optimal benefit. Clinical evidence indicates materials can keep moisture away from the skin in the diapered area, helping maintain proper skin hydration, minimizing irritation, and contributing to reduced rates of diaper rash. PMID:24961785

  4. What is the best microwave absorber?

    SciTech Connect

    Hutcheon, R.M.; Adams, F.P.; De Jong, M.S.

    1995-12-31

    The absorption of microwave power by samples with different shapes and dielectric properties was studied for single-mode excitation of a microwave applicator. Exact calculations were done of the quality factor, Q and the frequency shift of a cylindrically-symmetric cavity with a small, cylindrically-symmetric sample on-axis in the cavity, demonstrating the influence of sample shape and dielectric properties on the power absorption per unit volume of the sample. An approximate, but very general, analytical formalism was developed for calculating the power absorbed by the sample and thus the contribution of the sample to the Q of the cavity. This simple formalism is shown, by comparison with the exact calculations, to be quite accurate over a very broad range of properties. Thus, it can be used to calculate the power absorbed by samples which are smaller than the internal wavelength, and also to gain insight into the factors that influence the microwave absorption.

  5. Shock wave absorber having apertured plate

    DOEpatents

    Shin, Yong W.; Wiedermann, Arne H.; Ockert, Carl E.

    1985-01-01

    The shock or energy absorber disclosed herein utilizes an apertured plate maintained under the normal level of liquid flowing in a piping system and disposed between the normal liquid flow path and a cavity pressurized with a compressible gas. The degree of openness (or porosity) of the plate is between 0.01 and 0.60. The energy level of a shock wave travelling down the piping system thus is dissipated by some of the liquid being jetted through the apertured plate toward the cavity. The cavity is large compared to the quantity of liquid jetted through the apertured plate, so there is little change in its volume. The porosity of the apertured plate influences the percentage of energy absorbed.

  6. Shock wave absorber having apertured plate

    DOEpatents

    Shin, Y.W.; Wiedermann, A.H.; Ockert, C.E.

    1983-08-26

    The shock or energy absorber disclosed herein utilizes an apertured plate maintained under the normal level of liquid flowing in a piping system and disposed between the normal liquid flow path and a cavity pressurized with a compressible gas. The degree of openness (or porosity) of the plate is between 0.01 and 0.60. The energy level of a shock wave travelling down the piping system thus is dissipated by some of the liquid being jetted through the apertured plate toward the cavity. The cavity is large compared to the quantity of liquid jetted through the apertured plate, so there is little change in its volume. The porosity of the apertured plate influences the percentage of energy absorbed.

  7. Development and application of rotary shock absorber

    SciTech Connect

    Yamamoto, Kozo; Yamada, Toshihiro; Fukuyama, Katsura

    1995-12-31

    In recent years, rear suspension systems with a single shock absorber unit placed behind the engine, have been used primarily in the middle and large classes of motorcycles. Some features such as the longer rear wheel travel, progressive response characteristics and mass concentration at the center part of motorcycle are effective in improving maneuverability of the motorcycle. In the 1980s, the systems were introduced first in the off-road motorcycles and then in the on-road motorcycles. Performance of the systems are excellent, but there are demands for further improvement of suspension characteristics and space utility at the center part of motorcycle. For this purpose, the authors have developed a prototype of a rotary shock absorber and studied the applicability to modern motorcycles.

  8. Impedance matched thin metamaterials make metals absorbing.

    PubMed

    Mattiucci, N; Bloemer, M J; Aközbek, N; D'Aguanno, G

    2013-01-01

    Metals are generally considered good reflectors over the entire electromagnetic spectrum up to their plasma frequency. Here we demonstrate an approach to tailor their absorbing characteristics based on the effective metamaterial properties of thin, periodic metallo-dielectric multilayers by exploiting a broadband, inherently non-resonant, surface impedance matching mechanism. Based on this mechanism, we design, fabricate and test omnidirectional, thin (<1 micron), polarization independent, extremely efficient absorbers (in principle being capable to reach A > 99%) over a frequency range spanning from the UV to the IR. Our approach opens new venues to design cost effective materials for many applications such as thermo-photovoltaic energy conversion devices, light harvesting for solar cells, flat panel display, infrared detectors, stray light reduction, stealth and others. PMID:24220284

  9. Anomalous retroreflection from strongly absorbing nanoporous semiconductors.

    PubMed

    Prislopski, S Ya; Naumenko, E K; Tiginyanu, I M; Ghimpu, L; Monaico, E; Sirbu, L; Gaponenko, S V

    2011-08-15

    Pronounced retroreflection behavior is reported for a fishnet nanoporous strongly absorbing semiconductor material. Retroreflection features a half-cone about 0.35 rad along with diffusive specular reflection for all angles of incidence. Retroreflection is apparent by the naked eye with daylight illumination and exhibits no selectivity with respect to wavelength and polarization of incident light featuring minor depolarization of retroreflected light. The reflectance in the backward direction measures 12% with respect to a white scattering etalon. The phenomenon can be classified neither as coherent backscattering nor as Anderson localization of light. The primary model includes light scattering from strongly absorptive and refractive superwavelength clusters existing within the porous fishnet structure. A reasonable qualitative explanation is based on the fact that strict retroreflection obeys shorter paths inside absorbing medium, whereas all alternative paths will lead to stronger absorption of light. PMID:21847216

  10. Absorbing Software Testing into the Scrum Method

    NASA Astrophysics Data System (ADS)

    Tuomikoski, Janne; Tervonen, Ilkka

    In this paper we study, how to absorb software testing into the Scrum method. We conducted the research as an action research during the years 2007-2008 with three iterations. The result showed that testing can and even should be absorbed to the Scrum method. The testing team was merged into the Scrum teams. The teams can now deliver better working software in a shorter time, because testing keeps track of the progress of the development. Also the team spirit is higher, because the Scrum team members are committed to the same goal. The biggest change from test manager’s point of view was the organized Product Owner Team. Test manager don’t have testing team anymore, and in the future all the testing tasks have to be assigned through the Product Backlog.

  11. Impedance matched thin metamaterials make metals absorbing

    PubMed Central

    Mattiucci, N.; Bloemer, M. J.; Aközbek, N.; D'Aguanno, G.

    2013-01-01

    Metals are generally considered good reflectors over the entire electromagnetic spectrum up to their plasma frequency. Here we demonstrate an approach to tailor their absorbing characteristics based on the effective metamaterial properties of thin, periodic metallo-dielectric multilayers by exploiting a broadband, inherently non-resonant, surface impedance matching mechanism. Based on this mechanism, we design, fabricate and test omnidirectional, thin (<1 micron), polarization independent, extremely efficient absorbers (in principle being capable to reach A > 99%) over a frequency range spanning from the UV to the IR. Our approach opens new venues to design cost effective materials for many applications such as thermo-photovoltaic energy conversion devices, light harvesting for solar cells, flat panel display, infrared detectors, stray light reduction, stealth and others. PMID:24220284

  12. Ultra-broadband terahertz metamaterial absorber

    NASA Astrophysics Data System (ADS)

    Zhu, Jianfei; Ma, Zhaofeng; Sun, Wujiong; Ding, Fei; He, Qiong; Zhou, Lei; Ma, Yungui

    2014-07-01

    We demonstrated an ultra-broadband, polarization-insensitive, and wide-angle metamaterial absorber for terahertz (THz) frequencies using arrays of truncated pyramid unit structure made of metal-dielectric multilayer composite. In our design, each sub-layer behaving as an effective waveguide is gradually modified in their lateral width to realize a wideband response by effectively stitching together the resonance bands of different waveguide modes. Experimentally, our five layer sample with a total thickness 21 μm is capable of producing a large absorptivity above 80% from 0.7 to 2.3 THz up to the maximum measurement angle 40°. The full absorption width at half maximum of our device is around 127%, greater than those previously reported for THz frequencies. Our absorber design has high practical feasibility and can be easily integrated with the semiconductor technology to make high efficient THz-oriented devices.

  13. The ultimate chrome absorber in photomask making

    NASA Astrophysics Data System (ADS)

    Hashimoto, Masahiro; Iwashita, Hiroyuki; Kominato, Atsushi; Shishido, Hiroaki; Ushida, Masao; Mitsui, Hideaki

    2008-05-01

    193nm-immersion lithography is the most promising technology for 32nm-node device fabrication. A new Cr absorber (TFC) for 193-nm attenuated phase-shift blanks was developed to meet the photomask requirements without any additional process step, such as hardmask etching. TFC was introduced with a design concept of the vertical profile for shorter etching time, the over etching time reduction. As a result, the dry-etching time was dramatically improved by more than 20% shorter than the conventional Cr absorber (TF11) without any process changes. We confirmed that 150nm-resist thickness was possible by TFC. The 32nm technology-node requirement is fully supported by TFC with thinner CAR, such as resolution and CD performance.

  14. Infrared bolometers with silicon nitride micromesh absorbers

    NASA Technical Reports Server (NTRS)

    Bock, J. J.; Turner, A. D.; DelCastillo, H. M.; Beeman, J. W.; Lange, A. E.; Mauskopf, P. D.

    1996-01-01

    Sensitive far infrared and millimeter wave bolometers fabricated from a freestanding membrane of low stress silicon nitride are reported. The absorber, consisting of a metallized silicon nitride micromesh thermally isolated by radial legs of silicon nitride, is placed in an integrating cavity to efficiently couple to single mode or multiple mode infrared radiation. This structure provides low heat capacity, low thermal conduction and minimal cross section to energetic particles. A neutron transmutation doped Ge thermister is bump bonded to the center of the device and read out with evaporated Cr-Au leads. The limiting performance of the micromesh absorber is discussed and the recent results obtained from a 300 mK cold stage are summarized.

  15. Lightweight Energy Absorbers for Blast Containers

    NASA Technical Reports Server (NTRS)

    Balles, Donald L.; Ingram, Thomas M.; Novak, Howard L.; Schricker, Albert F.

    2003-01-01

    Kinetic-energy-absorbing liners made of aluminum foam have been developed to replace solid lead liners in blast containers on the aft skirt of the solid rocket booster of the space shuttle. The blast containers are used to safely trap the debris from small explosions that are initiated at liftoff to sever frangible nuts on hold-down studs that secure the spacecraft to a mobile launch platform until liftoff.

  16. Absorbable phenylpropenoyl sucroses from Polygala tenuifolia.

    PubMed

    She, Gaimei; Ba, Yinying; Liu, Yang; Lv, Hang; Wang, Wei; Shi, Renbing

    2011-01-01

    Three phenylpropenoyl sucroses--sibiricose A5, A6 and 3',6-disinapoyl sucrose--were isolated from the 30% EtOH extract of Polygala tenuifolia, which displayed antidepressant-like action. HPLC analysis indicated that the three phenylpropenoyl sucroses could be absorbed into serum. From the serum pharmacochemistry point of view, these three phenylpropenoyl sucroses might prevent or relieve depression. PMID:21716172

  17. Design and Manufacture of Energy Absorbing Materials

    SciTech Connect

    Duoss, Eric

    2014-05-28

    Learn about an ordered cellular material that has been designed and manufactured using direct ink writing (DIW), a 3-D printing technology being developed at LLNL. The new material is a patterned cellular material that can absorb mechanical energy-a cushion-while also providing protection against sheering. This material is expected to find utility in application spaces that currently use unordered foams, such as sporting and consumer goods as well as defense and aerospace.

  18. Design and Manufacture of Energy Absorbing Materials

    ScienceCinema

    Duoss, Eric

    2014-05-30

    Learn about an ordered cellular material that has been designed and manufactured using direct ink writing (DIW), a 3-D printing technology being developed at LLNL. The new material is a patterned cellular material that can absorb mechanical energy-a cushion-while also providing protection against sheering. This material is expected to find utility in application spaces that currently use unordered foams, such as sporting and consumer goods as well as defense and aerospace.

  19. Tech Transfer Webinar: Energy Absorbing Materials

    SciTech Connect

    Duoss, Eric

    2014-06-17

    A new material has been designed and manufactured at LLNL that can absorb mechanical energy--a cushion--while also providing protection against sheering. This ordered cellular material is 3D printed using direct ink writing techniques under development at LLNL. It is expected to find utility in application spaces that currently use unordered foams, such as sporting and consumer goods as well as defense and aerospace.

  20. Tech Transfer Webinar: Energy Absorbing Materials

    ScienceCinema

    Duoss, Eric

    2014-07-15

    A new material has been designed and manufactured at LLNL that can absorb mechanical energy--a cushion--while also providing protection against sheering. This ordered cellular material is 3D printed using direct ink writing techniques under development at LLNL. It is expected to find utility in application spaces that currently use unordered foams, such as sporting and consumer goods as well as defense and aerospace.

  1. Development of monofilar rotor hub vibration absorber

    NASA Technical Reports Server (NTRS)

    Duh, J.; Miao, W.

    1983-01-01

    A design and ground test program was conducted to study the performance of the monofilar absorber for vibration reduction on a four-bladed helicopter. A monofilar is a centrifugal tuned two degree-of-freedom rotor hub absorber that provides force attenuation at two frequencies using the same dynamic mass. Linear and non-linear analyses of the coupled monofilar/airframe system were developed to study tuning and attenuation characteristics. Based on the analysis, a design was fabricated and impact bench tests verified the calculated non-rotating natural frequencies and mode shapes. Performance characteristics were measured using a rotating absorber test facility. These tests showed significant attenuation of fixed-system 4P hub motions due to 3P inplane rotating-system hub forces. In addition, detuning effects of the 3P monofilar modal response were small due to the nonlinearities and tuning pin slippage. However, attenuation of 4P hub motions due to 5P inplane hub forces was poor. The performance of the 5P monofilar modal response was degraded by torsional motion of the dynamic mass relative to the support arm which resulted in binding of the dynamic components. Analytical design studies were performed to evaluate this torsional motion problem. An alternative design is proposed which may alleviate the torsional motion of the dynamic mass.

  2. Heaving buoys, point absorbers and arrays.

    PubMed

    Falnes, Johannes; Hals, Jørgen

    2012-01-28

    Absorption of wave energy may be considered as a phenomenon of interference between incident and radiated waves generated by an oscillating object; a wave-energy converter (WEC) that displaces water. If a WEC is very small in comparison with one wavelength, it is classified as a point absorber (PA); otherwise, as a 'quasi-point absorber'. The latter may be a dipole-mode radiator, for instance an immersed body oscillating in the surge mode or pitch mode, while a PA is so small that it should preferably be a source-mode radiator, for instance a heaving semi-submerged buoy. The power take-off capacity, the WEC's maximum swept volume and preferably also its full physical volume should be reasonably matched to the wave climate. To discuss this matter, two different upper bounds for absorbed power are applied in a 'Budal diagram'. It appears that, for a single WEC unit, a power capacity of only about 0.3 MW matches well to a typical offshore wave climate, and the full physical volume has, unfortunately, to be significantly larger than the swept volume, unless phase control is used. An example of a phase-controlled PA is presented. For a sizeable wave-power plant, an array consisting of hundreds, or even thousands, of mass-produced WEC units is required. PMID:22184661

  3. Shock wave absorber having a deformable liner

    DOEpatents

    Youngdahl, C.K.; Wiedermann, A.H.; Shin, Y.W.; Kot, C.A.; Ockert, C.E.

    1983-08-26

    This invention discloses a shock wave absorber for a piping system carrying liquid. The absorber has a plastically deformable liner defining the normal flow boundary for an axial segment of the piping system, and a nondeformable housing is spaced outwardly from the liner so as to define a gas-tight space therebetween. The flow capacity of the liner generally corresponds to the flow capacity of the piping system line, but the liner has a noncircular cross section and extends axially of the piping system line a distance between one and twenty times the diameter thereof. Gas pressurizes the gas-tight space equal to the normal liquid pressure in the piping system. The liner has sufficient structural capacity to withstand between one and one-half and two times this normal liquid pressures; but at greater pressures it begins to plastically deform initially with respect to shape to a more circular cross section, and then with respect to material extension by circumferentially stretching the wall of the liner. A high energy shock wave passing through the liner thus plastically deforms the liner radially into the gas space and progressively also as needed in the axial direction of the shock wave to minimize transmission of the shock wave beyond the absorber.

  4. Microscopic modeling of nitride intersubband absorbance

    NASA Astrophysics Data System (ADS)

    Montano, Ines; Allerman, A. A.; Wierer, J. J.; Moseley, M.; Skogen, E. J.; Tauke-Pedretti, A.; Vawter, G. A.

    III-nitride intersubband structures have recently attracted much interest because of their potential for a wide variety of applications ranging from electro-optical modulators to terahertz quantum cascade lasers. To overcome present simulation limitations we have developed a microscopic absorbance simulator for nitride intersubband devices. Our simulator calculates the band structure of nitride intersubband systems using a fully coupled 8x8 k.p Hamiltonian and determines the material response of a single period in a density-matrix-formalism by solving the Heisenberg equation including many-body and dephasing contributions. After calculating the polarization due to intersubband transitions in a single period, the resulting absorbance of a superlattice structure including radiative coupling between the different periods is determined using a non-local Green's-function formalism. As a result our simulator allows us to predict intersubband absorbance of superlattice structures with microscopically determined lineshapes and linewidths accounting for both many-body and correlation contributions. This work is funded by Sandia National Laboratories Laboratory Directed Research and Development program. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin.

  5. Broadband metasurface absorber for solar thermal applications

    NASA Astrophysics Data System (ADS)

    Wan, C.; Chen, L.; Cryan, M. J.

    2015-12-01

    In this paper we propose a broadband polarization-independent selective absorber for solar thermal applications. It is based on a metal-dielectric-metal metasurface structure, but with an interlayer of absorbing amorphous carbon rather than a low loss dielectric. Optical absorbance results derived from finite difference time domain modelling are shown for ultra-thin carbon layers in air and on 200 nm of gold for a range of carbon thicknesses. A gold-amorphous carbon-gold trilayer with a top layer consisting of a 1D grating is then optimised in 2D to give a sharp transition from strong absorption up to 2 μm to strong reflection above 2 μm resulting in good solar selective performance. The gold was replaced by the high-melting-point metal tungsten, which is shown to have very similar performance to the gold case. 3D simulations then show that the gold-based structure performs well as a square periodic array of squares, however there is low absorption around 400 nm. A cross-based structure is found to increase this absorption without significantly reducing the performance at longer wavelengths.

  6. An absorbed dose calorimeter for IMRT dosimetry

    NASA Astrophysics Data System (ADS)

    Duane, S.; Aldehaybes, M.; Bailey, M.; Lee, N. D.; Thomas, C. G.; Palmans, H.

    2012-10-01

    A new calorimeter for dosimetry in small and complex fields has been built. The device is intended for the direct determination of absorbed dose to water in moderately small fields and in composite fields such as IMRT treatments, and as a transfer instrument calibrated against existing absorbed dose standards in conventional reference conditions. The geometry, materials and mode of operation have been chosen to minimize detector perturbations when used in a water phantom, to give a reasonably isotropic response and to minimize the effects of heat transfer when the calorimeter is used in non-reference conditions in a water phantom. The size of the core is meant to meet the needs of measurement in IMRT treatments and is comparable to the size of the air cavity in a type NE2611 ionization chamber. The calorimeter may also be used for small field dosimetry. Initial measurements in reference conditions and in an IMRT head and neck plan, collapsed to gantry angle zero, have been made to estimate the thermal characteristics of the device, and to assess its performance in use. The standard deviation (estimated repeatability) of the reference absorbed dose measurements was 0.02 Gy (0.6%).

  7. Load limiting energy absorbing lightweight debris catcher

    NASA Technical Reports Server (NTRS)

    Kahn, Jon B. (Inventor); Schneider, William C. (Inventor)

    1991-01-01

    In the representative embodiment of the invention disclosed, a load limiting, energy absorbing net is arranged to overlay a normally-covered vent opening in the rear bulkhead of the space orbiter vehicle. Spatially-disposed flexible retainer straps are extended from the net and respectively secured to bulkhead brackets spaced around the vent opening. The intermediate portions of the straps are doubled over and stitched together in a pattern enabling the doubled-over portions to progressively separate at a predicable load designed to be well below the tensile capability of the straps as the stitches are successively torn apart by the forces imposed on the retainer members whenever the cover plate is explosively separated from the bulkhead and propelled into the net. By arranging these stitches to be successively torn away at a load below the strap strength in response to forces acting on the retainers that are less than the combined strength of the retainers, this tearing action serves as a predictable compact energy absorber for safely halting the cover plate as the retainers are extended as the net is deployed. The invention further includes a block of an energy-absorbing material positioned in the net for receiving loose debris produced by the explosive release of the cover plate.

  8. Wide band cryogenic ultra-high vacuum microwave absorber

    DOEpatents

    Campisi, Isidoro E.

    1992-01-01

    An absorber wave guide assembly for absorbing higher order modes of microwave energy under cryogenic ultra-high vacuum conditions, that absorbs wide-band multi-mode energy. The absorber is of a special triangular shape, made from flat tiles of silicon carbide and aluminum nitride. The leading sharp end of the absorber is located in a corner of the wave guide and tapers to a larger cross-sectional area whose center is located approximately in the center of the wave guide. The absorber is relatively short, being of less height than the maximum width of the wave guide.

  9. Wide band cryogenic ultra-high vacuum microwave absorber

    DOEpatents

    Campisi, I.E.

    1992-05-12

    An absorber waveguide assembly for absorbing higher order modes of microwave energy under cryogenic ultra-high vacuum conditions, that absorbs wide-band multi-mode energy. The absorber is of a special triangular shape, made from flat tiles of silicon carbide and aluminum nitride. The leading sharp end of the absorber is located in a corner of the waveguide and tapers to a larger cross-sectional area whose center is located approximately in the center of the wave guide. The absorber is relatively short, being of less height than the maximum width of the waveguide. 11 figs.

  10. Spore loads of Paranosema locustae (Microsporidia) in heavily infected grasshoppers (Orthoptera: Acridoidea) of the Argentine Pampas and Patagonia.

    PubMed

    Plischuk, Santiago; Bardi, Christian J; Lange, Carlos E

    2013-09-01

    Paranosema locustae, an entomopathogen of grasshoppers and locusts, remains the only microsporidium registered as a biocontrol agent. After introductions from North America, it became established in grasshopper communities of Argentina. We measured the infection intensity of field collected, heavily infected male and female adults of individuals belonging to six grasshopper species, five melanoplines (Melanoplinae) (Baeacris pseudopunctulatus, Dichroplus maculipennis, Dichroplus vittatus, Neopedies brunneri, Scotussa lemniscata), and one gomphocerine (Gomphocerinae) (Staurorhectus longicornis). Average spore load among heavily infected grasshoppers ranged from 8.7±0.5×10(7) to 1.1±0.7×10(9). Only females of B. pseudopunctulatus and S. longicornis showed significantly higher spore loads than the males. PMID:23796497

  11. A combined method to estimate parameters of neuron from a heavily noise-corrupted time series of active potential

    NASA Astrophysics Data System (ADS)

    Deng, Bin; Wang, Jiang; Che, Yenqiu

    2009-03-01

    A method that combines the means of unscented Kalman filter (UKF) with the technique of synchronization-based parameter estimation is introduced for estimating unknown parameters of neuron when only a heavily noise-corrupted time series of active potential is given. Compared with other synchronization-based methods, this approach uses the state variables estimated by UKF instead of the measured data to drive the auxiliary system. The synchronization-based approach supplies a systematic and analytical procedure for estimating parameters from time series; however, it is only robust against weak noise of measurement, so the UKF is employed to estimate state variables which are used by the synchronization-based method to estimate all unknown parameters of neuron model. It is found out that the estimation accuracy of this combined method is much higher than only using UKF or synchronization-based method when the data of measurement were heavily noise corrupted.

  12. The Cosmic X-Ray Background and the Population of the Most Heavily Obscured AGNs

    NASA Astrophysics Data System (ADS)

    Frontera, Filippo; Orlandini, Mauro; Landi, Raffaella; Comastri, Andrea; Fiore, Fabrizio; Setti, Giancarlo; Amati, Lorenzo; Costa, Enrico; Masetti, Nicola; Palazzi, Eliana

    2007-09-01

    We report on an accurate measurement of the CXB in the 15-50 keV range performed with the Phoswich Detection System (PDS) instrument aboard the BeppoSAX satellite. We establish that the most likely CXB intensity level at its emission peak (26-28 keV) is ~40 keV cm-2 s-1 sr-1, a value consistent with that derived from the best available CXB measurement obtained over 25 years ago with the first High Energy Astronomical Observatory (HEAO-1) satellite mission (Gruber et al.), whose intensity, lying well below the extrapolation of some lower energy measurements performed with focusing telescopes, was questioned in recent years. We find that 90% of the acceptable solutions of our best-fit model to the PDS data give a 20-50 keV CXB flux lower than 6.5×10-8 ergs cm-2 s-1 sr-1, which is 12% higher than that quoted by Gruber et al. when we use our best calibration scale. In combination with the CXB synthesis models we infer that about 25% of the intensity at ~30 keV arises from extremely obscured, Compton-thick AGNs (absorbing column density NH>1024 cm-2), while a much larger population would be implied by the highest intensity estimates. We also infer a mass density of supermassive black holes of ~3×105 Msolar Mpc-3. The summed contribution of resolved sources (Moretti et al.) in the 2-10 keV band exceeds our best-fit CXB intensity extrapolated to lower energies, but it is within our upper limit, so that any significant contribution to the CXB from sources other than AGNs, such as star-forming galaxies and diffuse warm-hot intergalactic medium (WHIM), is expected to be mainly confined below a few keV.

  13. Heavily Yb-doped phosphate fiber with hexagonal inner cladding prepared by the stack-and-draw method

    NASA Astrophysics Data System (ADS)

    Wang, Longfei; He, Dongbing; Hu, Lili; Chen, Danping

    2015-03-01

    The stack-and-draw method was first used to fabricate a heavily Yb-doped phosphate glass double-clad fiber with non-circular inner cladding. An output power of 11.1 W was extracted with slope efficiency of 51.2% from the fiber with 53 cm length. In addition, we also obtained a ~2.1 W output power from a fiber with the length ~9 cm.

  14. Lichens as biomonitors of uranium and other trace elements in an area of Kosovo heavily shelled with depleted uranium rounds

    NASA Astrophysics Data System (ADS)

    Di Lella, Luigi A.; Frati, Luisa; Loppi, Stefano; Protano, Giuseppe; Riccobono, Francesco

    This paper reports the results of a study using lichens as biomonitors to investigate the small-scale environmental distribution of uranium and other trace elements in an area of Kosovo (Djakovica) heavily shelled with depleted uranium (DU) anti-tank ammunition. The results of total uranium concentrations showed great variability and species-specific differences, mainly due to differences in the exposed surface area of the lichens. The uranium concentrations in lichen samples were rather similar at a site heavily shelled with DU ammunition and at a control site. Unexpectedly, the highest uranium concentrations were found at the control site. The observed U distribution can be explained by contamination of lichen thalli by soil particles. The soil geochemistry was similar at the two sampling sites. The 235U/ 238U ratios in the soil samples suggested a modest DU contribution only at the heavily shelled site. Measurements of U isotopes in lichens did not reveal DU pollution at the control site. The U isotopic ratios in lichens at the shelled site showed variable figures; only two samples were clearly contaminated by DU. There were no signs of contamination by other trace elements.

  15. The Effect of Detonation Wave Incidence Angle on the Acceleration of Flyers by Explosives Heavily Laden with Inert Additives

    NASA Astrophysics Data System (ADS)

    Loiseau, Jason; Georges, William; Frost, David; Higgins, Andrew

    2015-06-01

    The incidence angle of a detonation wave is often assumed to weakly influence the terminal velocity of an explosively driven flyer. For explosives heavily loaded with dense additives, this may not be true due to differences in momentum and energy transfer between detonation products, additive particles, and the flyer. For tangential incidence the particles are first accelerated against the flyer via an expansion fan, whereas they are first accelerated by the detonation wave in the normal case. In the current study we evaluate the effect of normal versus tangential incidence on the acceleration of flyers by nitromethane heavily loaded with a variety of additives. Normal detonation was initiated via an explosively driven slapper. Flyer acceleration was measured with heterodyne laser interferometry (PDV). The influence of wave angle is evaluated by comparing the terminal velocity in the two cases (i.e., normal and grazing) for the heavily loaded mixtures. The decrement in flyer velocity correlated primarily with additive volume fraction and had a weak dependence on additive density or particle size. The Gurney energy of the heterogeneous explosive was observed to increase with flyer mass, presumably due to the timescale over which impinging particles could transfer momentum.

  16. Modeling the Effect of Polychromatic Light in Quantitative Absorbance Spectroscopy

    ERIC Educational Resources Information Center

    Smith, Rachel; Cantrell, Kevin

    2007-01-01

    Laboratory experiment is conducted to give the students practical experience with the principles of electronic absorbance spectroscopy. This straightforward approach creates a powerful tool for exploring many of the aspects of quantitative absorbance spectroscopy.

  17. Solar-energy absorber: Active infrared (IR) trap

    NASA Technical Reports Server (NTRS)

    Brantley, L. W., Jr.

    1974-01-01

    Efficiency of solar-energy absorbers may be improved to 95% by actively cooling their intermediate glass plates. This approach may be of interest to manufacturers of solar absorbers and to engineers and scientists developing new sources of energy.

  18. Inorganic UV absorbers for the photostabilisation of wood-clearcoating systems: Comparison with organic UV absorbers

    NASA Astrophysics Data System (ADS)

    Aloui, F.; Ahajji, A.; Irmouli, Y.; George, B.; Charrier, B.; Merlin, A.

    2007-02-01

    Inorganic UV absorbers which are widely used today were originally designed neither as a UV blocker in coatings applications, nor for wood protection. In recent years however, there has been extensive interest in these compounds, especially with regard to their properties as a UV blocker in coating applications. In this work, we carried out a comparative study to look into some inorganic and organic UV absorbers used in wood coating applications. The aim of this study is to determine the photostabilisation performances of each type of UV absorbers, to seek possible synergies and the influences of different wood species. We have also searched to find eventual correlation between these performances and the influence of UV absorbers on the film properties. Our study has compared the performances of the following UV absorbers: hombitec RM 300, hombitec RM 400 from the Sachtleben Company; transparent yellow and red iron oxides from Sayerlack as inorganic UV absorbers; organic UV absorbers Tinuvin 1130 and Tinuvin 5151 from Ciba Company. The study was carried out on three wood species: Abies grandis, tauari and European oak. The environmental constraints (in particular the limitation of the emission of volatile organic compounds VOCs) directed our choice towards aqueous formulations marketed by the Sayerlack Arch Coatings Company. The results obtained after 800 h of dry ageing showed that the Tinuvins and the hombitecs present better wood photostabilisations. On the other hand in wet ageing, with the hombitec, there are appearances of some cracks and an increase in the roughness of the surface. This phenomenon is absent when the Tinuvins are used. With regard to these results, the thermomechanical analyses relating to the follow-up of the change of the glass transition temperature ( Tg) of the various coating systems, show a different behaviour between the two types of absorbers. However, contrary to organic UV absorbers, inorganic ones tend to increase Tg during ageing

  19. The NuSTAR View of Reflecting and Absorbing Circumnuclear Material in AGN

    NASA Astrophysics Data System (ADS)

    Rivers, Elizabeth

    2016-04-01

    The physical conditions and precise geometry of the accreting circumnuclear material in the vicinity of supermassive black holes remain open and critical questions. Between July 2012 and February 2013, NuSTAR and XMM-Newton performed four long-look joint observations of the type 1.8 Seyfert, NGC 1365. We have analyzed the variable absorption seen in these observations in order to characterize the geometry of the absorbing material. Two of the observations caught NGC 1365 in an unusually low absorption state, revealing complexity in the multi-layer absorbers which had previously been hidden, including a the Compton-thick torus, BLR clouds, and a patchy absorber with a variable column around 1022 cm-2 and a line of sight covering fraction of 0.3-0.9 which responds directly to the intrinsic source flux, possibly due to a wind geometry. We have also analyzed two NuSTAR observations of NGC 7582, a well-studied X-ray bright Seyfert 2 with moderately heavy highly variable absorption and strong reflection spectral features. Changes in the spectral shape and high reflection fractions have led to competing explanations: 1) the central X-ray source partially “shut off”, decreasing in intrinsic luminosity, with a delayed decrease in reflection features due to the light-crossing time of the Compton-thick material or 2) the source became more heavily obscured, with only a portion of the power law continuum leaking through. The high quality of the NuSTAR spectra above 10 keV give us the best look at the reflection hump to date and allow us to test these two scenarios.

  20. Grover walks on a line with absorbing boundaries

    NASA Astrophysics Data System (ADS)

    Wang, Kun; Wu, Nan; Kuklinski, Parker; Xu, Ping; Hu, Haixing; Song, Fangmin

    2016-06-01

    In this paper, we study Grover walks on a line with one and two absorbing boundaries. In particular, we present some results for the absorbing probabilities in both a semi-finite and finite line. Analytical expressions for these absorbing probabilities are presented by using the combinatorial approach. These results are perfectly matched with numerical simulations. We show that the behavior of Grover walks on a line with absorbing boundaries is strikingly different from that of classical walks and that of Hadamard walks.

  1. Method for absorbing an ion from a fluid

    DOEpatents

    Gao, Huizhen; Wang, Yifeng; Bryan, Charles R.

    2007-07-03

    A method for absorbing an ion from a fluid by using dispersing an organic acid into an anion surfactant solution, mixing in a divalent-metal containing compound and a trivalent-metal containing compound and calcining the resulting solid layered double hydroxide product to form an absorbent material and then contacting the absorbent material with an aqueous solution of cations or anions to be absorbed.

  2. [Absorbable coronary stents. New promising technology].

    PubMed

    Erbel, Raimund; Böse, Dirk; Haude, Michael; Kordish, Igor; Churzidze, Sofia; Malyar, Nasser; Konorza, Thomas; Sack, Stefan

    2007-06-01

    Coronary stent implantation started in Germany 20 years ago. In the beginning, the progress was very slow and accelerated 10 years later. Meanwhile, coronary stent implantation is a standard procedure in interventional cardiology. From the beginning of permanent stent implantation, research started to provide temporary stenting of coronary arteries, first with catheter-based systems, later with stent-alone technology. Stents were produced from polymers or metal. The first polymer stent implantation failed except the Igaki-Tamai stent in Japan. Newly developed absorbable polymer stents seem to be very promising, as intravascular ultrasound (IVUS) and optical coherence tomography have demonstrated. Temporary metal stents were developed based on iron and magnesium. Currently, the iron stent is tested in peripheral arteries. The absorbable magnesium stent (Biotronik, Berlin, Germany) was tested in peripheral arteries below the knee and meanwhile in the multicenter international PROGRESS-AMS (Clinical Performance and Angiographic Results of Coronary Stenting with Absorbable Metal Stents) study. The first magnesium stent implantation was performed on July 30, 2004 after extended experimental testing in Essen. The magnesium stent behaved like a bare-metal stent with low recoil of 5-7%. The stent struts were absorbed when tested with IVUS. Stent struts were not visible by fluoroscopy or computed tomography (CT) as well as magnetic resonance imaging (MRI). That means, that the magnesium stent is invisible and therefore CT and MRI can be used for imaging of interventions. Only using micro-CT the stent struts were visible. The absorption process could be demonstrated in a patient 18 days after implantation due to suspected acute coronary syndrome, which was excluded. IVUS showed a nice open lumen. Stent struts were no longer visible, but replaced by tissue indicating the previous stent location. Coronary angiography after 4 months showed an ischemia-driven target lesion

  3. [Performance of desulfurizing absorbent of roasted navajoite].

    PubMed

    Chen, Fang; Yang, Chun-ping; Gan, Hai-ming; Wu, Ting; Chen, Hai-lin; Chen, Hong; Xu, Ke-hui; Xie, Geng-xin

    2010-04-01

    An innovative flue gas desulfurization (FGD) coupling process was proposed in this study to overcome the problems in wet-type limestone/lime processes which include fouling, clogging, and difficulty of selling the by-products and the problems in traditional process for vanadium extraction from navajoite ore such as excessive consumption of sulfuric acid and emissions of pollutants. The performance of a jet bubbling reactor (JBR) at pilot-scale was evaluated using navajoite ore produced in the process of extracting vanadium pentoxide as desulfurization absorbent. Results showed that navajoite ore slurry achieved better desulfurization performance than limestone slurry. When the inlet flue gas pressure drop was 3.0 kPa, the gas flow was about 2350 m3 x h(-1) and the pH of the navajoite ore slurry was higher than 4.5, the desulfurization efficiency was stable about 90%. The SO2 removal efficiency appeared to increase along with the increasing of absorbent cycle-index. The efficiency of the second circulation was improved 3.5% compared to the first circulation. After an operating duration of 40 minutes, the leaching rate of vanadium pentoxide was about 20%, and reached 60% when the by-products were leached with 5% dilute sulfuric acid for 10 hours. The by-product from this process not only could be used to produce vanadium pentoxide which is a valuable industrial product, but also could significantly overcome the pollution problem existing in the traditional refining process of vanadium pentoxide when navajoite ore is used as the feed material. This FGD process using roasted navajoite slurry as absorbent is environmental sound and cost-effective, and shows the potential for application in the field of flue gas desulfurization as well as hydrometallurgy. PMID:20527168

  4. 21 CFR 886.3300 - Absorbable implant (scleral buckling method).

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Absorbable implant (scleral buckling method). 886... SERVICES (CONTINUED) MEDICAL DEVICES OPHTHALMIC DEVICES Prosthetic Devices § 886.3300 Absorbable implant (scleral buckling method). (a) Identification. An absorbable implant (scleral buckling method) is a...

  5. 21 CFR 886.3300 - Absorbable implant (scleral buckling method).

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Absorbable implant (scleral buckling method). 886... SERVICES (CONTINUED) MEDICAL DEVICES OPHTHALMIC DEVICES Prosthetic Devices § 886.3300 Absorbable implant (scleral buckling method). (a) Identification. An absorbable implant (scleral buckling method) is a...

  6. 21 CFR 886.3300 - Absorbable implant (scleral buckling method).

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Absorbable implant (scleral buckling method). 886... SERVICES (CONTINUED) MEDICAL DEVICES OPHTHALMIC DEVICES Prosthetic Devices § 886.3300 Absorbable implant (scleral buckling method). (a) Identification. An absorbable implant (scleral buckling method) is a...

  7. 21 CFR 886.3300 - Absorbable implant (scleral buckling method).

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Absorbable implant (scleral buckling method). 886... SERVICES (CONTINUED) MEDICAL DEVICES OPHTHALMIC DEVICES Prosthetic Devices § 886.3300 Absorbable implant (scleral buckling method). (a) Identification. An absorbable implant (scleral buckling method) is a...

  8. 21 CFR 886.3300 - Absorbable implant (scleral buckling method).

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Absorbable implant (scleral buckling method). 886... SERVICES (CONTINUED) MEDICAL DEVICES OPHTHALMIC DEVICES Prosthetic Devices § 886.3300 Absorbable implant (scleral buckling method). (a) Identification. An absorbable implant (scleral buckling method) is a...

  9. 21 CFR 878.4755 - Absorbable lung biopsy plug.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Absorbable lung biopsy plug. 878.4755 Section 878...) MEDICAL DEVICES GENERAL AND PLASTIC SURGERY DEVICES Surgical Devices § 878.4755 Absorbable lung biopsy plug. (a) Identification. A preformed (polymerized) absorbable lung biopsy plug is intended to...

  10. 21 CFR 880.5300 - Medical absorbent fiber.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Medical absorbent fiber. 880.5300 Section 880.5300... Devices § 880.5300 Medical absorbent fiber. (a) Identification. A medical absorbent fiber is a device intended for medical purposes that is made from cotton or synthetic fiber in the shape of a ball or a...

  11. 21 CFR 880.5300 - Medical absorbent fiber.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Medical absorbent fiber. 880.5300 Section 880.5300... Devices § 880.5300 Medical absorbent fiber. (a) Identification. A medical absorbent fiber is a device intended for medical purposes that is made from cotton or synthetic fiber in the shape of a ball or a...

  12. 21 CFR 880.5300 - Medical absorbent fiber.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Medical absorbent fiber. 880.5300 Section 880.5300...) MEDICAL DEVICES GENERAL HOSPITAL AND PERSONAL USE DEVICES General Hospital and Personal Use Therapeutic Devices § 880.5300 Medical absorbent fiber. (a) Identification. A medical absorbent fiber is a...

  13. 21 CFR 880.5300 - Medical absorbent fiber.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Medical absorbent fiber. 880.5300 Section 880.5300...) MEDICAL DEVICES GENERAL HOSPITAL AND PERSONAL USE DEVICES General Hospital and Personal Use Therapeutic Devices § 880.5300 Medical absorbent fiber. (a) Identification. A medical absorbent fiber is a...

  14. 21 CFR 868.5310 - Carbon dioxide absorber.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Carbon dioxide absorber. 868.5310 Section 868.5310...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5310 Carbon dioxide absorber. (a) Identification. A carbon dioxide absorber is a device that is intended for medical purposes and that is used in...

  15. 21 CFR 868.5300 - Carbon dioxide absorbent.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Carbon dioxide absorbent. 868.5300 Section 868...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5300 Carbon dioxide absorbent. (a) Identification. A carbon dioxide absorbent is a device intended for medical purposes that consists of...

  16. 21 CFR 868.5310 - Carbon dioxide absorber.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Carbon dioxide absorber. 868.5310 Section 868.5310...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5310 Carbon dioxide absorber. (a) Identification. A carbon dioxide absorber is a device that is intended for medical purposes and that is used in...

  17. 21 CFR 868.5310 - Carbon dioxide absorber.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Carbon dioxide absorber. 868.5310 Section 868.5310...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5310 Carbon dioxide absorber. (a) Identification. A carbon dioxide absorber is a device that is intended for medical purposes and that is used in...

  18. 21 CFR 868.5300 - Carbon dioxide absorbent.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Carbon dioxide absorbent. 868.5300 Section 868...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5300 Carbon dioxide absorbent. (a) Identification. A carbon dioxide absorbent is a device intended for medical purposes that consists of...

  19. 21 CFR 868.5300 - Carbon dioxide absorbent.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Carbon dioxide absorbent. 868.5300 Section 868...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5300 Carbon dioxide absorbent. (a) Identification. A carbon dioxide absorbent is a device intended for medical purposes that consists of...

  20. 21 CFR 868.5300 - Carbon dioxide absorbent.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Carbon dioxide absorbent. 868.5300 Section 868...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5300 Carbon dioxide absorbent. (a) Identification. A carbon dioxide absorbent is a device intended for medical purposes that consists of...

  1. 21 CFR 868.5300 - Carbon dioxide absorbent.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Carbon dioxide absorbent. 868.5300 Section 868...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5300 Carbon dioxide absorbent. (a) Identification. A carbon dioxide absorbent is a device intended for medical purposes that consists of...

  2. 21 CFR 868.5310 - Carbon dioxide absorber.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Carbon dioxide absorber. 868.5310 Section 868.5310...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5310 Carbon dioxide absorber. (a) Identification. A carbon dioxide absorber is a device that is intended for medical purposes and that is used in...

  3. 21 CFR 868.5310 - Carbon dioxide absorber.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Carbon dioxide absorber. 868.5310 Section 868.5310...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5310 Carbon dioxide absorber. (a) Identification. A carbon dioxide absorber is a device that is intended for medical purposes and that is used in...

  4. 40 CFR 65.150 - Absorbers used as control devices.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... parts per million by volume outlet concentration requirements as specified in § 65.63(a)(2), or 40 CFR... 40 Protection of Environment 16 2013-07-01 2013-07-01 false Absorbers used as control devices. 65... System or a Process § 65.150 Absorbers used as control devices. (a) Absorber equipment and...

  5. Acoustical model of a Shoddy fibre absorber

    NASA Astrophysics Data System (ADS)

    Manning, John Peter

    Shoddy fibres or "Shoddies" are a mixture of post-consumer and post-industrial fibres diverted from textile waste streams and recycled into their raw fibre form. They have found widespread use as a raw material for manufacturing sound absorbers that include, but are not limited to: automotive, architectural and home appliance applications. The purpose of this project is to develop a simple acoustic model to describe the acoustic behaviour of sound absorbers composed primarily of Shoddy fibres. The model requires knowledge of the material's bulk density only. To date, these materials have not been the focus of much published research and acoustical designers must rely on models that were developed for other materials or are overly complex. For modelling purposes, an equivalent fluid approach is chosen to balance complexity and accuracy. In deriving the proposed model, several popular equivalent fluid models are selected and the required input parameters for each model identified. The models are: the model of Delaney and Bazley, two models by Miki, the model of Johnson in conjunction with the model of Champoux and Allard and the model of Johnson in conjunction with the model of Lafarge. Characterization testing is carried out on sets of Shoddy absorbers produced using three different manufacturing methods. The measured properties are open porosity, tortuosity, airflow resistivity, the viscous and thermal characteristic lengths and the static thermal permeability. Empirical relationships between model parameters and bulk density are then derived and used to populate the selected models. This yields several 'simplified' models with bulk density as the only parameter. The most accurate model is then selected by comparing each model's prediction to the results of normal incidence sound absorption tests. The model of Johnson-Lafarge populated with the empirical relations is the most accurate model over the range of frequencies considered (approx. 300 Hz - 4000 Hz

  6. DHCAL with minimal absorber: measurements with positrons

    NASA Astrophysics Data System (ADS)

    Freund, B.; Neubüser, C.; Repond, J.; Schlereth, J.; Xia, L.; Dotti, A.; Grefe, C.; Ivantchenko, V.; Berenguer Antequera, J.; Calvo Alamillo, E.; Fouz, M.-C.; Marin, J.; Puerta-Pelayo, J.; Verdugo, A.; Brianne, E.; Ebrahimi, A.; Gadow, K.; Göttlicher, P.; Günter, C.; Hartbrich, O.; Hermberg, B.; Irles, A.; Krivan, F.; Krüger, K.; Kvasnicka, J.; Lu, S.; Lutz, B.; Morgunov, V.; Provenza, A.; Reinecke, M.; Sefkow, F.; Schuwalow, S.; Tran, H. L.; Garutti, E.; Laurien, S.; Matysek, M.; Ramilli, M.; Schroeder, S.; Bilki, B.; Norbeck, E.; Northacker, D.; Onel, Y.; Cvach, J.; Gallus, P.; Havranek, M.; Janata, M.; Kovalcuk, M.; Kvasnicka, J.; Lednicky, D.; Marcisovsky, M.; Polak, I.; Popule, J.; Tomasek, L.; Tomasek, M.; Sicho, P.; Smolik, J.; Vrba, V.; Zalesak, J.; van Doren, B.; Wilson, G. W.; Kawagoe, K.; Hirai, H.; Sudo, Y.; Suehara, T.; Sumida, H.; Takada, S.; Tomita, T.; Yoshioka, T.; Bilokin, S.; Bonis, J.; Cornebise, P.; Pöschl, R.; Richard, F.; Thiebault, A.; Zerwas, D.; Hostachy, J.-Y.; Morin, L.; Besson, D.; Chadeeva, M.; Danilov, M.; Markin, O.; Popova, E.; Gabriel, M.; Goecke, P.; Kiesling, C.; van der Kolk, N.; Simon, F.; Szalay, M.; Corriveau, F.; Blazey, G. C.; Dyshkant, A.; Francis, K.; Zutshi, V.; Kotera, K.; Ono, H.; Takeshita, T.; Ieki, S.; Kamiya, Y.; Ootani, W.; Shibata, N.; Jeans, D.; Komamiya, S.; Nakanishi, H.

    2016-05-01

    In special tests, the active layers of the CALICE Digital Hadron Calorimeter prototype, the DHCAL, were exposed to low energy particle beams, without being interleaved by absorber plates. The thickness of each layer corresponded approximately to 0.29 radiation lengths or 0.034 nuclear interaction lengths, defined mostly by the copper and steel skins of the detector cassettes. This paper reports on measurements performed with this device in the Fermilab test beam with positrons in the energy range of 1 to 10 GeV. The measurements are compared to simulations based on GEANT4 and a standalone program to emulate the detailed response of the active elements.

  7. Piston-rotaxanes as molecular shock absorbers.

    PubMed

    Sevick, E M; Williams, D R M

    2010-04-20

    We describe the thermomechanical response of a new molecular system that behaves as a shock absorber. The system consists of a rodlike rotaxane connected to a piston and tethered to a surface. The response of this system is dominated by the translational entropy of the rotaxane rings and can be calculated exactly. The force laws are contrasted with those for a rigid rod and a polymer. In some cases, the rotaxanes undergo a sudden transition to a tilted state when compressed. These piston-rotaxanes provide a potential motif for the design of a new class of materials with a novel thermomechanical response. PMID:20158174

  8. Optically absorbing nanoparticle mediated cell membrane permeabilization.

    PubMed

    Bhattacharyya, Kiran; Mehta, Smit; Viator, John

    2012-11-01

    Membrane permeabilization is imperative for gene and drug delivery systems, along with other cell manipulation methods, since the average eukaryotic cell membrane is not permeable to polar and large nonpolar molecules. Antibody conjugated optically absorbing gold nanospheres are targeted to the cell membrane of T47D breast cancer cell line and irradiated with 5 ns pulse, 20 Hz, 532 nm light to increase membrane permeability. Up to 90% permeabilization with less than 6% death is reported at radiant exposures up to 10 times lower than those of other comparable studies. PMID:23114334

  9. Exposure testing of solar absorber surfaces

    SciTech Connect

    Moore, S.W.

    1986-01-01

    The Los Alamos National Laboratory has been involved in supporting, monitoring and conducting exposure testing of solar materials for approximately ten years. The Laboratory has provided technical monitoring of the IITRI, DSET, Lockheed, and Berry contracts and has operated the Los Alamos exposure Facility for over five years. This report will outline some of the past exposure testing, the testing still in progress, and describe some of the major findings. While this report will primarily emphasize solar absorber surfaces, some of the significant findings relative to advanced glazing will be discussed.

  10. Cylinder light concentrator and absorber: theoretical description.

    PubMed

    Kildishev, Alexander V; Prokopeva, Ludmila J; Narimanov, Evgenii E

    2010-08-01

    We present a detailed theoretical description of a broadband omnidirectional light concentrator and absorber with cylinder geometry. The proposed optical "trap" captures nearly all the incident light within its geometric cross-section, leading to a broad range of possible applications--from solar energy harvesting to thermal light emitters and optoelectronic components. We have demonstrated that an approximate lamellar black-hole with a moderate number of homogeneous layers, while giving the desired ray-optical performance, can provide absorption efficiencies comparable to those of ideal devices with a smooth gradient in index. PMID:20721056

  11. A novel broadband waterborne acoustic absorber

    NASA Astrophysics Data System (ADS)

    Wang, Changxian; Wen, Weibin; Huang, Yixing; Chen, Mingji; Lei, Hongshuai; Fang, Daining

    2016-07-01

    In this paper, we extended the ray tracing theory in polar coordinate system, and originally proposed the Snell-Descartes law in polar coordinates. Based on these theories, a novel broadband waterborne acoustic absorber device was proposed. This device is designed with gradient-distributing materials along radius, which makes the incidence acoustic wave ray warps. The echo reduction effects of this device were investigated by finite element analysis, and the numerical results show that the reflectivity of acoustic wave for the new device is lower than that of homogenous and Alberich layers in almost all frequency 0-30 kHz at the same loss factor.

  12. Chandra and NTT Observations of Massive Young Stars in the Heavily Reddened Galactic Cluster Westerlund 1

    NASA Astrophysics Data System (ADS)

    Skinner, S. L.; Damineli, A.; Palla, F.; Zhekov, S. A.; Simmons, A. E.; Teodoro, M.

    2005-12-01

    The southern galactic starburst cluster Westerlund 1 (Wd1) contains a rich population of massive young stars that is spectacularly revealed in infrared images. Recent studies give a mean extinction in the range Av = 9.5 - 13.6 mag and age estimates of ˜3 - 5 Myr (Brandner et al. 2005, Clark et al. 2005). The cluster contains numerous supergiants, hypergiants, a LBV candidate, and at least 19 Wolf-Rayet (WR) stars. We present new results from Chandra X-ray and NTT near-IR observations of Wd1. Our immediate objectives are to obtain an X-ray census, identify optical or near-IR counterparts to the X-ray sources, and quantify the X-ray properties of the cluster members. Chandra detections include a newly-discovered 10.61 sec pulsar, the unusual B[e] supergiant W9, and half of the currently known WR stars in the cluster. The Chandra ACIS-S CCD spectrum of the Wd1 pulsar (CXO J164710.2-455217) can be acceptably reproduced by an absorbed soft blackbody emission model, but the model is not uniquely constrained by the existing data. A high-temperature component is clearly present in the X-ray spectrum of W9, suggesting that it is a close binary or unresolved multiple. Most of the Chandra WR detections are nitrogen-rich WN stars, but a few carbon-rich WC stars are surprisingly detected. At an assumed distance of 4 kpc, the X-ray luminosity of W87-239 (WC9) is two orders of magnitude greater than upper limits previously obtained for closer less-obscured single WC stars such as WR 135 (WC8, log Lx < 29.82 ergs/s; Skinner et al. 2005). The luminous X-ray emission and hot plasma in W87-239 point toward binarity. This study was supported by NASA/SAO grants GO5-6009X (PI: S.S.) and GO4-5003X (PI: S.Z.).

  13. Substructure and strengthening of heavily deformed single and two-phase metallic materials

    NASA Astrophysics Data System (ADS)

    Gil Sevillano, J.

    1991-06-01

    Work hardening of single-phase crystalline materials (and to some extent, coarse two-phase and dispersion hardened materials too) at low temperatures results from the competition of two dynamic processes: dislocation accumulation, during the long-range gliding of mobile dislocations and dynamic recovery, involving local rearrangements and length annihilation from mobile and stored dislocation interactions. Its complete understanding would be very useful for designing materials with maximized strength after heavy cold work. However, modelling of the strain-induced evolution of the dislocation substructure, an essential ingredient of any work hardening theory, is still far from satisfactory. On the other hand, some heavily deformed ductile two-phase in situ composites are only second to whiskers among the strongest metallic materials. At first sight, the main obstacle geometry for dislocation glide in lamellar or multifilamentary in situ composites being clear-cut, it can be thought that their strength and work hardening are completely understood. However, this is not so and several schools of thought propose different interpretations for the exaggerated departure of the stress-strain curves of in situ composites from the rule-of-mixtures curves built from those of their bulk components. This paper aims to discuss such interpretations. The composite Cu-Nb is taken as model material owing to the extensive and detailed mechanical and microstructural data available in the literature, including different deformation temperatures and two different strain paths. Fine pearlite Fe-Fe3C is the other obvious reference. Le durcissement par déformation des matériaux cristallins monophasés (et, dans une certaine mesure, des matériaux biphasés à grande dimension de phases, et des matériaux renforcés par une phase dispersée) à basse température résulte d'une compétition entre deux processus dynamiques: l'accumulation de dislocations pendant le glissement des

  14. Spacesuit Evaporator-Absorber-Radiator (SEAR)

    NASA Technical Reports Server (NTRS)

    Hodgson, Ed; Izenson, Mike; Chan, Weibo; Bue, Grant C.

    2012-01-01

    For decades advanced spacesuit developers have pursued a regenerable, robust nonventing system for heat rejection. Toward this end, this paper investigates linking together two previously developed technologies, namely NASA s Spacesuit Water Membrane Evaporator (SWME), and Creare s Lithium Chloride Absorber Radiator (LCAR). Heat from a liquid cooled garment is transported to SWME that provides cooling through evaporation. This water vapor is then captured by solid LiCl in the LCAR with a high enthalpy of absorption, resulting in sufficient temperature lift to reject heat to space by radiation. After the sortie, the LCAR would be heated up and dried in a regenerator to drive off and recover the absorbed evaporant. A engineering development prototype was built and tested in vacuum conditions at a sink temperature of 250 K. The LCAR was able to stably reject 75 W over a 7-hour period. A conceptual design of a full-scale radiator is proposed. Excess heat rejection above 240 W would be accomplished through venting of the evaporant. Loop closure rates were predicted for various exploration environment scenarios.

  15. Fabrication of THz Sensor with Metamaterial Absorber

    NASA Astrophysics Data System (ADS)

    Gonzalez, Hugo; Alves, Fabio; Karunasiri, Gamani

    The terahertz (THz) portion of the electromagnetic spectrum (0.1-10 THz) has not been fully utilized due to the lack of sensitive detectors. Real-time imaging in this spectral range has been demonstrated using uncooled infrared microbolometer cameras and external illumination provided by quantum cascade laser (QCL) based THz sources. However, the microbolometer pixels in the cameras have not been optimized to achieve high sensitivity in THz frequencies. Recently, we have developed a highly sensitive micromechanical THz sensor employing bi-material effect with an integrated metamaterial absorber tuned to the THz frequency of interest. The use of bi-material structures causes deflection on the sensor to as the absorbed THz radiation increases its temperature, which can be monitored optically by reflecting a light beam. This approach eliminates the integration of readout electronics needed in microbolometers. The absorption of THz by metamaterial can be tailored by controlling geometrical parameters. The sensors can be fabricated using conventional microelectronic materials and incorporated into pixels to form focal plane arrays (FPAs). In this presentation, characterization and readout of a THz sensor with integrated metamaterial structure will be described. Supported by DoD.

  16. QCSEE fan exhaust bulk absorber treatment evaluation

    NASA Technical Reports Server (NTRS)

    Bloomer, H. E.; Samanich, N. E.

    1980-01-01

    The purpose of the experimental program reported herein was to evaluate the acoustic suppression capability of bulk absorber material designed for use in the fan exhaust duct walls of the QCSEE UTW (under-the-wing) engine and to compare it with other means of acoustic suppression. The paper includes comparison of the acoustic suppression to the original design for the QCSEE UTW engine fan duct which consisted of phased SDOF (single-degree-of-freedom) wall treatment and a splitter and also with the splitter removed. The method of approach consisted of mounting the UTW engine on the test stand of the Lewis Engine Noise Facility with an appropriate array of far-field microphones in order to measure the acoustic levels of the various configurations. Peak suppression was about as predicted with the bulk absorber configuration; however, the broadband characteristics were not attained. Post-test inspection revealed surface oil contamination on the bulk material which could have caused the loss in bandwidth suppression.

  17. Metamaterial perfect absorber based hot electron photodetection.

    PubMed

    Li, Wei; Valentine, Jason

    2014-06-11

    While the nonradiative decay of surface plasmons was once thought to be only a parasitic process that limits the performance of plasmonic devices, it has recently been shown that it can be harnessed in the form of hot electrons for use in photocatalysis, photovoltaics, and photodetectors. Unfortunately, the quantum efficiency of hot electron devices remains low due to poor electron injection and in some cases low optical absorption. Here, we demonstrate how metamaterial perfect absorbers can be used to achieve near-unity optical absorption using ultrathin plasmonic nanostructures with thicknesses of 15 nm, smaller than the hot electron diffusion length. By integrating the metamaterial with a silicon substrate, we experimentally demonstrate a broadband and omnidirectional hot electron photodetector with a photoresponsivity that is among the highest yet reported. We also show how the spectral bandwidth and polarization-sensitivity can be manipulated through engineering the geometry of the metamaterial unit cell. These perfect absorber photodetectors could open a pathway for enhancing hot electron based photovoltaic, sensing, and photocatalysis systems. PMID:24837991

  18. Competing reaction model with many absorbing configurations.

    PubMed

    de Andrade, M F; Figueiredo, W

    2010-02-01

    We study a competitive reaction model between two monomers A and B on a linear lattice. We assume that monomer A can react with a nearest-neighbor monomer A or B , but reactions between monomers of type B are prohibited. We include in our model lateral interactions between monomers as well as the effects of temperature of the catalyst. The model is considered in the adsorption controlled limit, where the reaction rate is infinitely larger than the adsorption rate of the monomers. We employ site and pair mean-field approximations as well as static Monte Carlo simulations. We determine the phase diagram of the model in the plane y_{A} versus temperature, where y_{A} is the probability that a monomer of the type A arrives at the surface. This phase diagram shows regions of active and absorbing states separated by a line of continuous phase transitions. Despite the absorbing state of the model to be strongly dependent on temperature, we show that the static critical exponents of the model belong to the same universality class of the directed percolation. PMID:20365537

  19. Erbium concentration dependent absorbance in tellurite glass

    SciTech Connect

    Sazali, E. S. Rohani, M. S. Sahar, M. R. Arifin, R. Ghoshal, S. K. Hamzah, K.

    2014-09-25

    Enhancing the optical absorption cross-section in topically important rare earth doped tellurite glasses is challenging for photonic devices. Controlled synthesis and detailed characterizations of the optical properties of these glasses are important for the optimization. The influence of varying concentration of Er{sup 3+} ions on the absorbance characteristics of lead tellurite glasses synthesized via melt-quenching technique are investigated. The UV-Vis absorption spectra exhibits six prominent peaks centered at 490, 526, 652, 800, 982 and 1520 nm ascribed to the transitions in erbium ion from the ground state to the excited states {sup 4}F{sub 7/2}, {sup 2}H{sub 11/2}, {sup 4}F{sub 9/2}, {sup 4}I{sub 9/2}, {sup 2}H{sub 11/2} and {sup 4}I{sub 13/2}, respectively. The results are analyzed by means of optical band gap E{sub g} and Urbach energy E{sub u}. The values of the energy band gap are found decreased from 2.82 to 2.51 eV and the Urbach energy increased from 0.15 to 0.24 eV with the increase of the Er{sub 2}O{sub 3} concentration from 0 to 1.5 mol%. The excellent absorbance of the prepared tellurite glasses makes them suitable for fabricating solid state lasers.

  20. A shock absorber model for structure-borne noise analyses

    NASA Astrophysics Data System (ADS)

    Benaziz, Marouane; Nacivet, Samuel; Thouverez, Fabrice

    2015-08-01

    Shock absorbers are often responsible for undesirable structure-borne noise in cars. The early numerical prediction of this noise in the automobile development process can save time and money and yet remains a challenge for industry. In this paper, a new approach to predicting shock absorber structure-borne noise is proposed; it consists in modelling the shock absorber and including the main nonlinear phenomena responsible for discontinuities in the response. The model set forth herein features: compressible fluid behaviour, nonlinear flow rate-pressure relations, valve mechanical equations and rubber mounts. The piston, base valve and complete shock absorber model are compared with experimental results. Sensitivity of the shock absorber response is evaluated and the most important parameters are classified. The response envelope is also computed. This shock absorber model is able to accurately reproduce local nonlinear phenomena and improves our state of knowledge on potential noise sources within the shock absorber.

  1. Composite neutron absorbing coatings for nuclear criticality control

    DOEpatents

    Wright, Richard N.; Swank, W. David; Mizia, Ronald E.

    2005-07-19

    Thermal neutron absorbing composite coating materials and methods of applying such coating materials to spent nuclear fuel storage systems are provided. A composite neutron absorbing coating applied to a substrate surface includes a neutron absorbing layer overlying at least a portion of the substrate surface, and a corrosion resistant top coat layer overlying at least a portion of the neutron absorbing layer. An optional bond coat layer can be formed on the substrate surface prior to forming the neutron absorbing layer. The neutron absorbing layer can include a neutron absorbing material, such as gadolinium oxide or gadolinium phosphate, dispersed in a metal alloy matrix. The coating layers may be formed by a plasma spray process or a high velocity oxygen fuel process.

  2. Absorber Alignment Measurement Tool for Solar Parabolic Trough Collectors: Preprint

    SciTech Connect

    Stynes, J. K.; Ihas, B.

    2012-04-01

    As we pursue efforts to lower the capital and installation costs of parabolic trough solar collectors, it is essential to maintain high optical performance. While there are many optical tools available to measure the reflector slope errors of parabolic trough solar collectors, there are few tools to measure the absorber alignment. A new method is presented here to measure the absorber alignment in two dimensions to within 0.5 cm. The absorber alignment is measured using a digital camera and four photogrammetric targets. Physical contact with the receiver absorber or glass is not necessary. The alignment of the absorber is measured along its full length so that sagging of the absorber can be quantified with this technique. The resulting absorber alignment measurement provides critical information required to accurately determine the intercept factor of a collector.

  3. Container and method for absorbing and reducing hydrogen concentration

    DOEpatents

    Wicks, George G.; Lee, Myung W.; Heung, Leung K.

    2001-01-01

    A method for absorbing hydrogen from an enclosed environment comprising providing a vessel; providing a hydrogen storage composition in communication with a vessel, the hydrogen storage composition further comprising a matrix defining a pore size which permits the passage of hydrogen gas while blocking the passage of gaseous poisons; placing a material within the vessel, the material evolving hydrogen gas; sealing the vessel; and absorbing the hydrogen gas released into the vessel by the hydrogen storage composition. A container for absorbing evolved hydrogen gas comprising: a vessel having an interior and adapted for receiving materials which release hydrogen gas; a hydrogen absorbing composition in communication with the interior, the composition defining a matrix surrounding a hydrogen absorber, the matrix permitting the passage of hydrogen gas while excluding gaseous poisons; wherein, when the vessel is sealed, hydrogen gas, which is released into the vessel interior, is absorbed by the hydrogen absorbing composition.

  4. Determination of decay coefficients for combustors with acoustic absorbers

    NASA Technical Reports Server (NTRS)

    Mitchell, C. E.; Espander, W. R.; Baer, M. R.

    1972-01-01

    An analytical technique for the calculation of linear decay coefficients in combustors with acoustic absorbers is presented. Tuned circumferential slot acoustic absorbers were designed for the first three transverse modes of oscillation, and decay coefficients for these absorbers were found as a function of backing distance for seven different chamber configurations. The effectiveness of the absorbers for off-design values of the combustion response and acoustic mode is also investigated. Results indicate that for tuned absorbers the decay coefficient increases approximately as the cube of the backing distance. For most off-design situations the absorber still provides a damping effect. However, if an absorber designed for some higher mode of oscillation is used to damp lower mode oscillations, a driving effect is frequently found.

  5. Method of absorbing UF.sub.6 from gaseous mixtures in alkamine absorbents

    DOEpatents

    Lafferty, Robert H.; Smiley, Seymour H.; Radimer, Kenneth J.

    1976-04-06

    A method of recovering uranium hexafluoride from gaseous mixtures employing as an absorbent a liquid composition at least one of the components of which is chosen from the group consisting of ethanolamine, diethanolamine, and 3-methyl-3-amino-propane-diol-1,2.

  6. Nearby Galaxies as Damped Lyman alpha Absorbers

    NASA Astrophysics Data System (ADS)

    Rao, Sandhya

    1993-12-01

    The evolution of the neutral hydrogen content of galaxies as a function of time is an important constraint on processes in galactic evolution. We present a comprehensive, statistical description of the HI content and distribution within galaxies at the present epoch and compare these statistics with the properties of HI associated with ``damped Lyman alpha '' absorption systems at high redshift that are observed in the spectra of QSOs. Omega_ {HI}(z=0), the HI mass density at the present epoch relative to the present critical mass density, is found to be (2.3 +/- 0.6) times 10(-4) h75(-1) , consistent with the decreasing trend of the HI content with time deduced from QSO absorption line statistics for redshifts from about 4 to 0.5 (Lanzetta 1993). Spiral galaxies contain an overwhelming 94% of this neutral hydrogen mass. The rest is contained in irregulars (3%), and S0s plus ellipticals (3%). Spirals also offer the largest cross-section to line-of-sight absorption of light from QSOs. By considering nearby spirals as potential absorbers, the interception probability as a function of the HI column density, N(HI), is derived for comparison with the cross-sections inferred from observations of damped Lyman alpha systems. Consistent with previous studies, the comparison shows that the damped Ly alpha lines are created by absorbers that subtend larger cross-sections than present-day spirals by a factor of 5 implying that galaxies were either larger or more numerous at z ~ 2.5. We are also investigating the statistics of damped Lyman alpha absorbers in the redshift range 0.2 1.5.

  7. Inhalation of concentrated ambient particulate matter near a heavily trafficked road stimulates antigen-induced airway responses in mice.

    PubMed

    Kleinman, Michael T; Hamade, Ali; Meacher, Dianne; Oldham, Michael; Sioutas, Constantinos; Chakrabarti, Bhabesh; Stram, Dan; Froines, John R; Cho, Arthur K

    2005-09-01

    The goal of this study was to test the following hypotheses: (1) exposure to mobile emissions from mobile sources close to a heavily trafficked roadway will exacerbate airway inflammation and allergic airway responses in a sensitized mouse model, and (2) the magnitude of allergic airway disease responses will decrease with increasing distance from the roadway. A particle concentrator and a mobile exposure facility were used to expose ovalbumin (OVA)-sensitized BALB/c mice to purified air and concentrated fine and concentrated ultrafine ambient particles at 50 m and 150 m downwind from a roadway that was heavily impacted by emissions from heavy duty diesel-powered vehicles. After exposure, we assessed interleukin (IL)-5, IL-13, OVA-specific immunoglobulin E, OVA-specific immunoglobulin G1, and eosinophil influx as biomarkers of allergic responses and numbers of polymorphonuclear leukocytes as a marker of inflammation. The study was performed over a two-year period, and there were differences in the concentrations and compositions of ambient particulate matter across those years that could have influenced our results. However, averaged over the two-year period, exposure to concentrated ambient particles (CAPs) increased the biomarkers associated with airway allergies (IL-5, immunoglobulin E, immunoglobulin G1 and eosinophils). In addition, mice exposed to CAPs 50 m downwind of the roadway had, on the average, greater allergic responses and showed greater indications of inflammation than did mice exposed to CAPs 150 m downwind. This study is consistent with the hypothesis that exposure to CAPs close to a heavily trafficked roadway influenced allergic airway responses. PMID:16259423

  8. Enabling novel functionality in heavily doped ZnO:Ga by nanostructuring: an efficient plasmonic refractive index sensor

    NASA Astrophysics Data System (ADS)

    Kuznetsov, Alexander S.; Schäfer, Peter; John, Wilfred; Prasai, Deepak; Sadofev, Sergey; Kalusniak, Sascha

    2016-01-01

    We demonstrate a proof-of-concept refractive index sensor based on heavily doped ZnO:Ga nanostructured in a grating configuration, which supports free space excitation of propagating surface plasmons. The bulk sensitivity of the sensor of 4.9 × 103 nm per refractive index unit, achieved in the mid-infrared spectral range with the first grating prototype, surpasses that of the noble metal counterparts by three to four times. Sensing performance is discussed in the light of numerical simulations of the spatial profile of the near field of surface plasmon polaritons.

  9. Current-voltage spectroscopy of dopant-induced quantum-dots in heavily n-doped junctionless nanowire transistors

    SciTech Connect

    Wang, Hao; Han, Weihua Ma, Liuhong; Li, Xiaoming; Hong, Wenting; Yang, Fuhua

    2014-03-31

    We demonstrate current-voltage spectroscopy of dopant-induced quantum dots in heavily n-doped junctionless nanowire transistors (JNTs) at low temperatures. The similar multiple-split current peak features for both single-channel and multiple-channel JNTs are found at the initial stage of conduction below the temperature of 75 K. The temperature stability of the pinch-off voltage, affected by activated electrons from defects and donor ionization, has been effectively improved by the 20 nm-width nanowires. The transition temperature for single electron tunneling to thermal activated transport is dependent on the ionization energy of dopants.

  10. Enabling novel functionality in heavily doped ZnO:Ga by nanostructuring: an efficient plasmonic refractive index sensor.

    PubMed

    Kuznetsov, Alexander S; Schäfer, Peter; John, Wilfred; Prasai, Deepak; Sadofev, Sergey; Kalusniak, Sascha

    2016-01-15

    We demonstrate a proof-of-concept refractive index sensor based on heavily doped ZnO:Ga nanostructured in a grating configuration, which supports free space excitation of propagating surface plasmons. The bulk sensitivity of the sensor of 4.9 × 10(3) nm per refractive index unit, achieved in the mid-infrared spectral range with the first grating prototype, surpasses that of the noble metal counterparts by three to four times. Sensing performance is discussed in the light of numerical simulations of the spatial profile of the near field of surface plasmon polaritons. PMID:26629968

  11. Measurement of steady-state minority-carrier transport parameters in heavily doped n-type silicon

    NASA Technical Reports Server (NTRS)

    Del Alamo, Jesus A.; Swanson, Richard M.

    1987-01-01

    The relevant hole transport and recombination parameters in heavily doped n-type silicon under steady state are the hole diffusion length and the product of the hole diffusion coefficient times the hole equilibrium concentration. These parameters have measured in phosphorus-doped silicon grown by epitaxy throughout nearly two orders of magnitude of doping level. Both parameters are found to be strong functions of donor concentration. The equilibrium hole concentration can be deduced from the measurement. A rigid shrinkage of the forbidden gap appears as the dominant heavy doping mechanism in phosphorus-doped silicon.

  12. Recanalization of a Heavily Calcified Chronic Total Occlusion in a Femoropopliteal Artery Using a Wingman Crossing Catheter

    PubMed Central

    Inoue, Naoto; Tanaka, Akiko

    2016-01-01

    We present a 77-year-old female with heavily calcified chronic total occlusions (CTO) in a superficial femoral artery treated by endovascular therapy using a Wingman crossing catheter, which is an over-the-wire catheter with a metallic blade, controlled manually. The blade could probe and track the calcified cap of CTO, wherein any hydrophilic guidewires or looped wires could not penetrate. Moreover, the Wingman could proceed through the occlusion and introduce a guidewire into distal intramedial lumen as a support catheter. Finally, wire crossing was achieved using a bi-directional approach. The Wingman can be a simple solution for crossing calcified peripheral CTO. PMID:27375810

  13. Electrical shock absorber for docking control system

    NASA Astrophysics Data System (ADS)

    Niwa, Shohei; Suzuki, Masayuki; Hibino, Ryoichi; Ito, Mitsuo

    Results are reported from a preliminary experimental study examining an electromechanical actuator for a docking system in space, with emphasis on the attenuation and shock-absorbing characteristics of the actuator. A laboratory prototype of an electromechanical docking system which uses a sonar ranging system as a substitute for the laser range sensor and is controlled by a microprocessor is presented. The configuration of the experimental system consists of a rack and pinion gear actuator, a servo motor, sensors, a digital controller and an air-lifted docking target. For the design of the attenuator controller, the linear quadratic Gaussian (LQG) control design method is applied. For the purpose of attenuation on a specified frequency band, the application of a frequency-weighted LQG method and frequency domain method such as H2 and H-infinity control theory are considered.

  14. Electromagnetic radiation absorbers and modulators comprising polyaniline

    DOEpatents

    Epstein, Arthur J.; Ginder, John M.; Roe, Mitchell G.; Hajiseyedjavadi, Hamid

    1992-01-01

    A composition for absorbing electromagnetic radiation, wherein said electromagnetic radiation possesses a wavelength generally in the range of from about 1000 Angstroms to about 50 meters, wherein said composition comprises a polyaniline composition of the formula ##STR1## where y can be equal to or greater than zero, and R.sup.1 and R.sup.2 are independently selected from the group containing of H, --OCH.sub.3, --CH.sub.3, --F, --Cl, --Br, --I, NR.sup.3 .sub.2, --NHCOR.sup.3, --OH, --O.sup.-, SR.sup.3, --OCOR.sup.3, --NO.sub.2, --COOH, --COOR.sup.3, --COR.sup.3, --CHO, and --CN, where R.sup.3 is a C.sub.1 to C.sub.8 alkyl, aryl or aralkyl group.

  15. Absorbing layers for the Dirac equation

    SciTech Connect

    Pinaud, Olivier

    2015-05-15

    This work is devoted to the construction of perfectly matched layers (PML) for the Dirac equation, that not only arises in relativistic quantum mechanics but also in the dynamics of electrons in graphene or in topological insulators. While the resulting equations are stable at the continuous level, some care is necessary in order to obtain a stable scheme at the discrete level. This is related to the so-called fermion doubling problem. For this matter, we consider the numerical scheme introduced by Hammer et al. [19], and combine it with the discretized PML equations. We state some arguments for the stability of the resulting scheme, and perform simulations in two dimensions. The perfectly matched layers are shown to exhibit, in various configurations, superior absorption than the absorbing potential method and the so-called transport-like boundary conditions.

  16. Transient radiative transfer through scattering absorbing media

    SciTech Connect

    Mitra, K.; Kumar, S.

    1996-12-31

    This paper outlines the formulation of the different methods for determining transient radiative transfer through scattering absorbing media. A boundary driven radiative problem is considered in a one-dimensional plane-parallel slab. The different methods of solving the transient radiative transfer equation include the P{sub 1}, P{sub 3}, and P{sub 5} approximations, two-flux method, and eight, twelve and sixteen discrete ordinates methods. In addition, the general transient radiative transfer equation is also solved by direct numerical integration without any simplifying assumptions. Different orders of approximation for the phase function are considered as is a parametric analysis of the different parameters such as the scattering albedo and optical depth is performed. The propagation speed obtained and the magnitude of the transmitted and back-scattered fluxes for different models obtained are a function of the approximation used to represent the intensity distribution.

  17. Novel active vibration absorber with magnetorheological fluid

    NASA Astrophysics Data System (ADS)

    Gerlach, T.; Ehrlich, J.; Böse, H.

    2009-02-01

    Disturbing vibrations diminish the performance of technical high precision devices significantly. In search of a suitable solution for reducing these vibrations, a novel concept of active vibration reduction was developed which exploits the special properties of magnetorheological fluids. In order to evaluate the concept of such an active vibration absorber (AVA) a demonstrator was designed and manufactured. This demonstrator generates a force which counteracts the motion of the vibrating body. Since the counterforce is generated by a centrifugal exciter, the AVA provides the capability to compensate vibrations even in two dimensions. To control the strength of the force transmitted to the vibrating body, the exciter is based on a tunable MR coupling. The AVA was integrated in an appropriate testing device to investigate its performance. The recorded results show a significant reduction of the vibration amplitudes by an order of magnitude.

  18. Absorbed doses from temporomandibular joint radiography

    SciTech Connect

    Brooks, S.L.; Lanzetta, M.L.

    1985-06-01

    Thermoluminescent dosimeters were used in a tissue-equivalent phantom to measure doses of radiation absorbed by various structures in the head when the temporomandibular joint was examined by four different radiographic techniques--the transcranial, transorbital, and sigmoid notch (Parma) projections and the lateral tomograph. The highest doses of radiation occurred at the point of entry for the x-ray beam, ranging from 112 mrad for the transorbital view to 990 mrad for the sigmoid notch view. Only the transorbital projection a radiation dose to the lens of the eye. Of the four techniques evaluated, the lateral tomograph produced the highest doses to the pituitary gland and the bone marrow, while the sigmoid notch radiograph produced the highest doses to the parotid gland.

  19. Microcellular ceramic foams for radar absorbing structures

    SciTech Connect

    Huling, J.; Phillips, D.

    1996-09-01

    This is the final report of a one-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The goal of this project is to develop a lightweight, semi-structural, radar-absorbing ceramic foam that can be incorporated into aircraft exhaust systems to replace many of the currently used dense ceramic parts and thereby improve the radar cross section. Although the conventional processes for producing ceramic foams have not been able to provide materials that meet the design specifications for high strength at low density, we have developed and demonstrated a novel sol-gel emulsion process for preparing microcellular ceramic foams in which compositional and microstructural control is expected to provide the requisite high-temperature radar-absorption, strength-to-weight ratio, and thermal insulative properties.

  20. Skin interaction with absorbent hygiene products.

    PubMed

    Runeman, Bo

    2008-01-01

    Skin problems due to the use of absorbent hygiene products, such as diapers, incontinence pads, and feminine sanitary articles, are mostly due to climate or chafing discomfort. If these conditions are allowed to prevail, these may develop into an irritant contact dermatitis and eventually superficial skin infections. Skin humidity and aging skin are among the most significant predisposing and aggravating factors for dermatitis development. Improved product design features are believed to explain the decline in observed diaper dermatitis among infants. Where adult incontinence-related skin problems are concerned, it is very important to apply a holistic perspective to understand the influences due to the individual's incontinence level and skin condition, as well as the hygiene and skin care measures provided. Individuals with frail, sensitive skin or with skin diseases may preferably have to use high-quality products, equipped with superabsorbent polymers and water vapor-permeable back sheets, to minimize the risk of skin complications. PMID:18280904

  1. Cusps, self-organization, and absorbing states.

    PubMed

    Bonachela, Juan A; Alava, Mikko; Muñoz, Miguel A

    2009-05-01

    Elastic interfaces embedded in (quenched) random media exhibit metastability and stick-slip dynamics. These nontrivial dynamical features have been shown to be associated with cusp singularities of the coarse-grained disorder correlator. Here we show that annealed systems with many absorbing states and a conservation law but no quenched disorder exhibit identical cusps. On the other hand, similar nonconserved systems in the directed percolation class are also shown to exhibit cusps but of a different type. These results are obtained both by a recent method to explicitly measure disorder correlators and by defining an alternative new protocol inspired by self-organized criticality, which opens the door to easily accessible experimental realizations. PMID:19518401

  2. Photoinduced molecular reorientation of absorbing liquid crystals

    NASA Astrophysics Data System (ADS)

    Marrucci, L.; Paparo, D.

    1997-08-01

    The phenomenon of photoinduced molecular reorientation of absorbing nematic liquid crystals is analyzed in a macroscopic general framework and with a specific molecular model. The photoinduced torque responsible for the reorientation is shown to describe a transfer of angular momentum from the molecule center-of-mass degrees of freedom to the rotational ones, mediated by molecular friction. As a consequence, a photoinduced stress tensor is predicted to develop together with the torque in the illuminated fluid. A molecular expression of the photoinduced torque is derived with a rigorous procedure, valid both for a pure material and for a dye-liquid-crystal mixture. This torque expression corrects those reported in previous works on the same subject. The photoinduced torque is evaluated analytically in a simple approximate limit.

  3. Energy harvesting from an autoparametric vibration absorber

    NASA Astrophysics Data System (ADS)

    Yan, Zhimiao; Hajj, Muhammad R.

    2015-11-01

    The combined control and energy harvesting characteristics of an autoparametric vibration absorber consisting of a base structure subjected to the external force and a cantilever beam with a tip mass are investigated. The piezoelectric sheets are attached to the cantilever beam to convert the vibrations of the base structure into electrical energy. The coupled nonlinear representative model is developed by using the extended Hamiton’s principle. The effects of the electrical load resistance on the frequency and damping ratio of the cantilever beam are analyzed. The impacts of the external force and load resistance on the structural displacements of the base structure and the beam and on the level of harvested energy are determined. The results show that the initial conditions have a significant impact on the system’s response. The relatively high level of energy harvesting is not necessarily accompanied with the minimum displacements of the base structure.

  4. Strength function under the absorbing boundary condition

    NASA Astrophysics Data System (ADS)

    Iwasaki, M.; Otani, R.; Ito, M.

    2014-12-01

    The strength function of the linear response by the external field is calculated in the formalism of the absorbing boundary condition (ABC). The dipole excitation of a schematic two-body system is treated in the present study. The extended completeness relation, which is assumed on the analogy of the formulation in the complex scaling method (CSM), is applied to the calculation of the strength function. The calculation of the strength function is successful in the present formalism and hence, the extended completeness relation seems to work well in the ABC formalism. The contributions from the resonance and the non-resonant continuum is also analyzed according to the decomposition of the energy levels in the extended completeness relation.

  5. Porous Carbon Nanoparticle Networks with Tunable Absorbability

    PubMed Central

    Dai, Wei; Kim, Seong Jin; Seong, Won-Kyeong; Kim, Sang Hoon; Lee, Kwang-Ryeol; Kim, Ho-Young; Moon, Myoung-Woon

    2013-01-01

    Porous carbon materials with high specific surface areas and superhydrophobicity have attracted much research interest due to their potential application in the areas of water filtration, water/oil separation, and oil-spill cleanup. Most reported superhydrophobic porous carbon materials are fabricated by complex processes involving the use of catalysts and high temperatures but with low throughput. Here, we present a facile single-step method for fabricating porous carbon nanoparticle (CNP) networks with selective absorbability for water and oils via the glow discharge of hydrocarbon plasma without a catalyst at room temperature. Porous CNP networks were grown by the continuous deposition of CNPs at a relatively high deposition pressure. By varying the fluorine content, the porous CNP networks exhibited tunable repellence against liquids with various degrees of surface tension. These porous CNP networks could be applied for the separation of not only water/oil mixtures but also mixtures of liquids with different surface tension levels. PMID:23982181

  6. Absorbing layers for the Dirac equation

    NASA Astrophysics Data System (ADS)

    Pinaud, Olivier

    2015-05-01

    This work is devoted to the construction of perfectly matched layers (PML) for the Dirac equation, that not only arises in relativistic quantum mechanics but also in the dynamics of electrons in graphene or in topological insulators. While the resulting equations are stable at the continuous level, some care is necessary in order to obtain a stable scheme at the discrete level. This is related to the so-called fermion doubling problem. For this matter, we consider the numerical scheme introduced by Hammer et al. [19], and combine it with the discretized PML equations. We state some arguments for the stability of the resulting scheme, and perform simulations in two dimensions. The perfectly matched layers are shown to exhibit, in various configurations, superior absorption than the absorbing potential method and the so-called transport-like boundary conditions.

  7. Olive oil phenols are absorbed in humans.

    PubMed

    Vissers, Maud N; Zock, Peter L; Roodenburg, Annet J C; Leenen, Rianne; Katan, Martijn B

    2002-03-01

    Animal and in vitro studies suggest that olive oil phenols are effective antioxidants. The most abundant phenols in olive oil are the nonpolar oleuropein- and ligstroside-aglycones and the polar hydroxytyrosol and tyrosol. The aim of this study was to gain more insight into the metabolism of those phenols in humans. We measured their absorption in eight healthy ileostomy subjects. We also measured urinary excretion in the ileostomy subjects and in 12 volunteers with a colon. Subjects consumed three different supplements containing 100 mg of olive oil phenols on separate days in random order. Ileostomy subjects consumed a supplement with mainly nonpolar phenols, one with mainly polar phenols and one with the parent compound oleuropein-glycoside. Subjects with a colon consumed a supplement without phenols (placebo) instead of the supplement with oleuropein-glycoside. Ileostomy effluent and urine were collected for 24 h after supplement intake. Tyrosol and hydroxytyrosol concentrations were low (< 4 mol/100 mol of intake) in the ileostomy effluent, and no aglycones were detected. We estimated that the apparent absorption of phenols was at least 55-66% of the ingested dose. Absorption was confirmed by the excretion of tyrosol and hydroxytyrosol in urine. In ileostomy subjects, 12 mol/100 mol and in subjects with a colon, 6 mol/100 mol of the phenols from the nonpolar supplement were recovered in urine as tyrosol or hydroxytyrosol. In both subject groups, 5--6 mol/100 mol of the phenols was recovered from the polar supplement. When ileostomy subjects were given oleuropein-glycoside, 16 mol/100 mol was recovered in 24-h urine, mainly in the form of hydroxytyrosol. Thus, humans absorb a large part of ingested olive oil phenols and absorbed olive oil phenols are extensively modified in the body. PMID:11880564

  8. Dynamic vibration absorbers for vibration control within a frequency band

    NASA Astrophysics Data System (ADS)

    Yang, Cheng; Li, Deyu; Cheng, Li

    2011-04-01

    The use of dynamic vibration absorbers to control the vibration of a structure in both narrow and broadbands is discussed in this paper. As a benchmark problem, a plate incorporating multiple vibration absorbers is formulated, leading to an analytical solution when the number of absorbers yields one. Using this analytical solution, control mechanisms of the vibration absorber in different frequency bandwidths are studied; the coupling properties due to the introduction of the absorber into the host structure are analyzed; and the control performance of the absorber in different control bandwidths is examined with respect to its damping and location. It is found that the interaction between the plate and the absorber by means of the reaction force from the absorber plays a dominant role in a narrow band control, while in a relatively broadband control the dissipation by the absorber damping governs the control performance. When control bandwidth further enlarges, the optimal locations of the absorbers are not only affected by the targeted mode, but also by the other plate modes. These locations need to be determined after establishing a trade-off between the targeted mode and other modes involved in the coupling. Finally, numerical findings are assessed based on a simply-supported plate and a fair agreement between the predicted and measured results is obtained.

  9. Design of multiband metamaterial absorber based on artificial magnetic conductor

    NASA Astrophysics Data System (ADS)

    Dang, Kezheng; He, Zijian; Li, Zhigang; Miao, Lei; Liu, Hao

    2015-10-01

    We present a general method to design multiband absorber by replacing the ground plane in a conventional metamaterial absorber with an artificial magnetic conductor. Due to its unique property of in-phase reflection at some specific frequency, the artificial magnetic conductor is used to introduce new absorption in the operation band. Meanwhile, out of the in-phase reflection band, the original absorbing capability of the absorber is reserved. To demonstrate it, we design a metamaterial absorber comprising three layers which are grids patterned resistive frequency selective surface, dielectric layer and the ground plane respectively. With an appropriate design, the absorber performs an absorbing peak at about 10 GHz. Then, we utilize a single band artificial magnetic conductor at 6.25 GHz and a dual-band one at 6.27 GHz and 8.17 GHz, which are both lossy and comprised of patches array varying in periodic size with a thickness of 0.6 mm, to replace the ground plane in the metamaterial absorber separately. The reflectivity of these multiband absorbers are simulated, and experiments are carried out later. Experimental results agree well with the simulations. All results verified that the method presented at the beginning is effective. The results show that additional absorptions exist at the frequencies where microwaves are nearly reflected in phase on the artificial magnetic conductor. Meanwhile the original absorbing capability of the metamaterial absorber has been preserved mostly. Based on the artificial magnetic conductor, the multiband absorber performs better with an increasing absorption bandwidth from 8.5 GHz to 10 GHz compared to the metamaterial absorber.

  10. Features of the band structure and conduction mechanisms in the n-HfNiSn semiconductor heavily doped with Ru

    SciTech Connect

    Romaka, V. A.; Rogl, P.; Romaka, V. V.; Stadnyk, Yu. V.; Korzh, R. O.; Krayovskyy, V. Ya.; Horyn, A. M.

    2014-12-15

    The crystal and electronic structure and energy and kinetic properties of the n-HfNiSn semiconductor heavily doped with a Ru acceptor impurity are investigated in the temperature and Ru concentration ranges T = 80–400 K and N{sub A}{sup Ru} ≈ 9.5 × 10{sup 19}−5.7 × 10{sup 20} cm{sup −3} (x = 0–0.03), respectively. The mechanism of structural-defect generation is established, which changes the band gap and degree of compensation of the semiconductor and consists in the simultaneous concentration reduction and elimination of donor structural defects by means of the displacement of ∼1% of Ni atoms from the Hf (4a) positions, the generation of acceptor structural defects upon the substitution of Ru atoms for Ni atoms in the 4c positions, and the generation of donor defects in the form of vacancies in the Sn (4b) positions. The calculated electronic structure of HfNi{sub 1−x}Ru{sub x}Sn is consistent with the experiment. The results obtained are discussed within the Shklovsky-Efros model for a heavily doped and compensated semiconductor.

  11. Features of conduction mechanisms in n-HfNiSn semiconductor heavily doped with a Rh acceptor impurity

    SciTech Connect

    Romaka, V. A.; Rogl, P.; Stadnyk, Yu. V.; Romaka, V. V.; Hlil, E. K.; Krajovskii, V. Ya.; Horyn, A. M.

    2013-09-15

    The crystal structure and electron-density distribution, as well as the energy, kinetic, and magnetic characteristics of n-HfNiSn intermetallic semiconductor heavily doped with a Rh acceptor impurity in the temperature range T = 80-400 K, in the acceptor-concentration range N{sub A}{sup Rh} Almost-Equal-To 9.5 Multiplication-Sign 10{sup 19}-1.9 Multiplication-Sign 10{sup 21} cm{sup -3} (x = 0.005-0.10), and in magnetic fields H {<=} 10 kG are investigated. It is established that doping is accompanied by a simultaneous decrease in concentration, the elimination of donor-type structural defects (to x Almost-Equal-To 0.02), and an increase in the concentration of acceptor-type structural defects (0 < x {<=} 0.10). The dependence of the degree of semiconductor compensation on temperature is revealed. A model of the spatial arrangement of atoms in HfNi{sub 1-x}Rh{sub x}Sn is proposed, and the results of calculating the electron structure based on this model agree with the results of investigations of the kinetic and magnetic characteristics of the semiconductor. The results are discussed within the context of the Shklovskii-Efros model for a heavily doped and compensated semiconductor.

  12. Reduction of threading dislocation density in Ge/Si using a heavily As-doped Ge seed layer

    NASA Astrophysics Data System (ADS)

    Lee, Kwang Hong; Bao, Shuyu; Wang, Bing; Wang, Cong; Yoon, Soon Fatt; Michel, Jurgen; Fitzgerald, Eugene A.; Tan, Chuan Seng

    2016-02-01

    High quality germanium (Ge) epitaxial film is grown directly on silicon (001) substrate with 6° off-cut using a heavily arsenic (As) doped Ge seed layer. The growth steps consists of (i) growth of a heavily As-doped Ge seed layer at low temperature (LT, at 400 °C), (ii) Ge growth with As gradually reduced to zero at high temperature (HT, at 650 °C), (iii) pure Ge growth at HT. This is followed by thermal cyclic annealing in hydrogen at temperature ranging from 600 to 850 °C. Analytical characterization have shown that the Ge epitaxial film with a thickness of ˜1.5 µm experiences thermally induced tensile strain of 0.20% with a treading dislocation density (TDD) of mid 106/cm2 which is one order of magnitude lower than the control group without As doping and surface roughness of 0.37 nm. The reduction in TDD is due to the enhancement in velocity of dislocations in an As-doped Ge film.

  13. NUSTAR Unveils a Heavily Obscured Low-luminosity Active Galactic Nucleus in the Luminous Infrared Galaxy NGC 6286

    NASA Astrophysics Data System (ADS)

    Ricci, C.; Bauer, F. E.; Treister, E.; Romero-Cañizales, C.; Arevalo, P.; Iwasawa, K.; Privon, G. C.; Sanders, D. B.; Schawinski, K.; Stern, D.; Imanishi, M.

    2016-03-01

    We report the detection of a heavily obscured active galactic nucleus (AGN) in the luminous infrared galaxy (LIRG) NGC 6286 identified in a 17.5 ks Nuclear Spectroscopic Telescope Array observation. The source is in an early merging stage and was targeted as part of our ongoing NuSTAR campaign observing local luminous and ultra-luminous infrared galaxies in different merger stages. NGC 6286 is clearly detected above 10 keV and by including the quasi-simultaneous Swift/XRT and archival XMM-Newton and Chandra data, we find that the source is heavily obscured (NH ≃(0.95-1.32) × 1024 cm-2) with a column density consistent with being Compton-thick (CT, {log}({N}{{H}}/{{cm}}-2)≥slant 24). The AGN in NGC 6286 has a low absorption-corrected luminosity (L2-10 keV ˜ 3-20 × 1041 erg s-1) and contributes ≲1% to the energetics of the system. Because of its low luminosity, previous observations carried out in the soft X-ray band (<10 keV) and in the infrared did not notice the presence of a buried AGN. NGC 6286 has multiwavelength characteristics typical of objects with the same infrared luminosity and in the same merger stage, which might imply that there is a significant population of obscured low-luminosity AGNs in LIRGs that can only be detected by sensitive hard X-ray observations.

  14. Features of the band structure and conduction mechanisms of n-HfNiSn semiconductor heavily Lu-doped

    SciTech Connect

    Romaka, V. A.; Rogl, P.; Romaka, V. V.; Kaczorowski, D.; Stadnyk, Yu. V.; Korzh, R. O.; Krayovskyy, V. Ya.; Kovbasyuk, T. M.

    2015-03-15

    The crystal and electronic structures, energy, kinetic, and magnetic characteristics of n-HfNiSn semiconductor heavily doped with a Lu acceptor impurity in the ranges T = 80–400 K and N{sub A}{sup Lu} ≈ 1.9 × 10{sup 20}−1.9 × 10{sup 21} cm{sup −3} (x = 0.01–0.10) at H ≤ 10 kG is studied. The nature of the structural-defect generation mechanism leading to changes in the band gap and the degree of semiconductor compensation is determined. Its essence is the simultaneous reduction and elimination of donor-type structural defects due to the displacement of ∼1% of Ni atoms from the Hf (4a) site, the generation of acceptor-type structural defects by substituting Ni atoms with Lu atoms at the 4c site, and the generation of donor-type defects such as vacancies at the Sn (4b) site. The results of calculations of the electronic structure of Hf{sub 1−x}Lu{sub x}NiSn are in agreement with experimental data. The results are discussed within the model of a heavily doped and compensated Shklovskii-Efros semiconductor.

  15. London penetration depth in heavily over-doped Ba(Fe1-xCox)2As2

    NASA Astrophysics Data System (ADS)

    Murphy, Jason; Kim, H.; Tanata, M. A.; Thaler, A.; Canfield, P. C.; Welp, U.; Kwok, W. K.; Prozorov, R.

    2012-02-01

    The low-temperature variation of London penetration depth, δλ(T), has been previously studied in heavily over-doped Ba(Fe1-xNix)2As2 [1] and the authors suggested the development of line nodes. Similar conclusion was made from thermal conductivity measurements in Ba(Fe1-xCox)2As2 [2]. However, δλ(T) in this system has only been measured for x <=x=0.102 [3], which is not far enough from optimal doping. Here we report tunnel - diode resonator (TDR) measurements in heavily overdoped single crystals of Ba(Fe1-xCox)2As2 with Co content of x=0.108 (Tc=14.8 K) and x=0.127 (Tc=9 K. We found a robust power-law behavior of δλ= A T^n with n=2.5 and n=2.11 respectively. To test whether the nodes are symmetry imposed or accidental, samples were irradiated with heavy ions. The produced disorder, leads to a decrease in Tc and of the exponent n. These results effects will be discussed in a context of unconventional pairing in Fe-based superconductors. [4pt] [1] C. Martin et. al., Phys. Rev. B 81, 060505 (2010).[0pt] [2] J.-Ph. Reid et. al., Phys. Rev. B 82, 064501 (2010).[0pt] [3] R.T. Gordon et.al. Phys. Rev. B 82, 054507 (2010).

  16. Effect of heavily doping with boron on electronic structures and optical properties of β-SiC

    NASA Astrophysics Data System (ADS)

    Feng, Gui-Ying; Fang, Xiao-Yong; Wang, Jun-Jun; Zhou, Yan; Lu, Ran; Yuan, Jie; Cao, Mao-Sheng

    2010-06-01

    The electronic structures and optical properties of heavily boron (B)-doped zinc blende silicon carbide (β-SiC) have been investigated using the plane-wave pseudo-potential method with the generalized gradient approximation (GGA) based on density functional theory. The doped models Si nBC n-1 ( n=4, 32) have been constructed by β-SiC unit cell. The calculated results show that the band gap of β-SiC transforms from indirect band gap to direct band gap with band gap shrink after carbon atom is replaced by boron atom. The dielectric constant of heavily B-doped β-SiC in low frequency is found to be remarkably larger, so it may act as a new dielectric material. Furthermore, after B doping, absorption peaks appear in the ultra-violet band (5-20 eV) and infrared band (0-2 eV). The ultra-violet absorption is similar to the undoped β-SiC. The infrared absorption would intensify with the increase of doping concentration, and absorption edge emerges redshift.

  17. A study on snubber elimination using energy absorbers: Final report

    SciTech Connect

    Khalafallah, M.Z.; Lee, H.M.; Dong, M.Y.; Wilkenson, R.C.

    1987-03-01

    This report summarizes the results of a snubber elimination study performed by Bechtel Power Corporation (Bechtel) using energy absorbers. Energy absorbers are used here as one of three separate snubber elimination/optimization methods evaluated by independent contractors in a coordinated EPRI program. As a starting baseline, each method considers systems selected from existing operating plants, which were originally designed with snubbers. Energy absorbers used in this study were developed by Bechtel based on earlier success in experimentally demonstrating the concept of energy absorbing restraints on the shaker table at the University of California at Berkeley. ASME code Case N-420 provides rules for construction of energy absorbers under the provisions of Section III of the code. First applications of energy absorbers to nuclear plants are currently being reviewed by the NRC on the Peach Bottom Atomic Power Station and the Point Beach Atomic Plant.

  18. Application of magnetorheological fluid in industrial shock absorbers

    NASA Astrophysics Data System (ADS)

    Milecki, Andrzej; Hauke, Mikołaj

    2012-04-01

    The paper presents investigation results of a semi-active industrial shock absorber with magnetorheological (MR) fluid, which is capable of controlling the stopping process of moving objects, e.g. on transportation lines. The proposed solution makes it possible to adjust the braking force (by electronic controller) to the kinetic energy of the moving object. The paper presents an overview of passive shock absorbers. Next, the design concept of a semi-active shock absorber with the MR fluid is proposed. The theoretical model and the simulation model of the MR absorber and the stopping process are presented. The paper reports investigations of a prototype MR shock absorber used to stop a mass moving on an inclined plane. The braking force of the absorber was changed by an electronic control system according to the current position of the moving mass. Finally, the simulation and investigation results are discussed and compared.

  19. Refractory plasmonics with titanium nitride: broadband metamaterial absorber.

    PubMed

    Li, Wei; Guler, Urcan; Kinsey, Nathaniel; Naik, Gururaj V; Boltasseva, Alexandra; Guan, Jianguo; Shalaev, Vladimir M; Kildishev, Alexander V

    2014-12-17

    A high-temperature stable broadband plasmonic absorber is designed, fabricated, and optically characterized. A broadband absorber with an average high absorption of 95% and a total thickness of 240 nm is fabricated, using a refractory plasmonic material, titanium nitride. This absorber integrates both the plasmonic resonances and the dielectric-like loss. It opens a path for the interesting applications such as solar thermophotovoltaics and optical circuits. PMID:25327161

  20. Vertical-plane pendulum absorbers for minimizing helicopter vibratory loads

    NASA Technical Reports Server (NTRS)

    Amer, K. B.; Neff, J. R.

    1974-01-01

    The use of pendulum dynamic absorbers mounted on the blade root and operating in the vertical plane to minimize helicopter vibratory loads was discussed. A qualitative description was given of the concept of the dynamic absorbers and some results of analytical studies showing the degree of reduction in vibratory loads attainable are presented. Operational experience of vertical plane dynamic absorbers on the OH-6A helicopter is also discussed.

  1. Neutron-absorbing amorphous alloys for cladding coatings

    NASA Astrophysics Data System (ADS)

    Sevryukov, O. N.; Fedotov, V. T.; Polyansky, A. A.

    2016-04-01

    This paper shows developed compositions of neutron-absorbing cladding alloys based on nickel and containing such elements as B, Gd, Hf, and Mn. The techniques for application of coatings from these alloys on the surface of structural steels have been improved. It has been shown that the amorphous neutron-absorbing coating is more uniform than the crystalline one. The experimental data on the adhesion of cladding coatings with a steel substrate and their neutron-absorbing capacity have been obtained.

  2. Absorbing boundaries in the mean-field approximation

    SciTech Connect

    Jhala, Chirag; Dreissigacker, Ingo; Lein, Manfred

    2010-12-15

    Absorbing boundaries in the mean-field approximation are investigated and applied to small systems interacting with strong laser fields. Two types of calculations are considered: (i) a variational approach with a complex absorbing potential included in the full Hamiltonian and (ii) the inclusion of a complex absorbing potential in the single-particle equations. It is elucidated that the second approach outperforms the variational approach for small grids.

  3. Absorbed dose measurements and predictions on LDEF

    NASA Technical Reports Server (NTRS)

    Frank, A. L.; Benton, E. V.; Armstrong, T. W.; Colborn, B. L.

    1993-01-01

    The overall radiation environment of the Long Duration Exposure Facility (LDEF) was determined in part through the use of thermoluminescent detectors (TLD's) which were included in several experiments. The results given are from four experiments (A0015 Biostack, M0004 Fiber Optics Data Link, P0004 Seeds in Space, and P0006 Linear Energy Transfer Spectrum Measurement) and represent a large fraction of existing absorbed dose data. The TLD's were located on the leading and the trailing edges and the Earth end of the spacecraft under various shielding depths (0.48 to 15.4 g/sq cm). The measured absorbed doses were found to reflect both directional dependence of incident trapped protons and shielding. At the leading edge, doses ranged from 2.10 to 2.58 Gy under shielding of 2.90 to 1.37 g/sq cm Al equivalent (M0004). At the trailing edge, doses varied from 3.04 to 4.49 Gy under shielding of 11.7 to 3.85 g/sq cm (A0015), doses varied from 2.91 to 6.64 Gy under shielding of 11.1 to 0.48 g/sq cm (P0004), and a dose range of 2.66 to 6.48 Gy was measured under shielding of 15.4 to 0.48 g/sq cm (P0006). At the Earth end of the spacecraft, doses from 2.41 to 3.93 Gy were found under shielding of 10.0 to 1.66 g/sq cm (A0015). The effect of the trapped proton anisotropy was such that the western side of LDEF received more than 2 times the dose of the eastern side at shielding depths of approximately 1 g/sq cm. Calculations utilizing a directional model of trapped proton spectra predict smaller doses than those measured, being about 50 percent of measured values at the trailing edge and Earth end, and about 80 percent near the leading edge.

  4. Optimal active vibration absorber - Design and experimental results

    NASA Technical Reports Server (NTRS)

    Lee-Glauser, Gina; Juang, Jer-Nan; Sulla, Jeffrey L.

    1993-01-01

    An optimal active vibration absorber can provide guaranteed closed-loop stability and control for large flexible space structures with collocated sensors/actuators. The active vibration absorber is a second-order dynamic system which is designed to suppress any unwanted structural vibration. This can be designed with minimum knowledge of the controlled system. Two methods for optimizing the active vibration absorber parameters are illustrated: minimum resonant amplitude and frequency matched active controllers. The Controls-Structures Interaction Phase-1 Evolutionary Model at NASA LaRC is used to demonstrate the effectiveness of the active vibration absorber for vibration suppression. Performance is compared numerically and experimentally using acceleration feedback.

  5. Dual band metamaterial perfect absorber based on artificial dielectric "molecules".

    PubMed

    Liu, Xiaoming; Lan, Chuwen; Li, Bo; Zhao, Qian; Zhou, Ji

    2016-01-01

    Dual band metamaterial perfect absorbers with two absorption bands are highly desirable because of their potential application areas such as detectors, transceiver system, and spectroscopic imagers. However, most of these dual band metamaterial absorbers proposed were based on resonances of metal patterns. Here, we numerically and experimentally demonstrate a dual band metamaterial perfect absorber composed of artificial dielectric "molecules" with high symmetry. The artificial dielectric "molecule" consists of four "atoms" of two different sizes corresponding to two absorption bands with near unity absorptivity. Numerical and experimental absorptivity verify that the dual-band metamaterial absorber is polarization insensitive and can operate in wide-angle incidence. PMID:27406699

  6. Optimal active vibration absorber: Design and experimental results

    NASA Technical Reports Server (NTRS)

    Lee-Glauser, Gina; Juang, Jer-Nan; Sulla, Jeffrey L.

    1992-01-01

    An optimal active vibration absorber can provide guaranteed closed-loop stability and control for large flexible space structures with collocated sensors/actuators. The active vibration absorber is a second-order dynamic system which is designed to suppress any unwanted structural vibration. This can be designed with minimum knowledge of the controlled system. Two methods for optimizing the active vibration absorber parameters are illustrated: minimum resonant amplitude and frequency matched active controllers. The Controls-Structures Interaction Phase-1 Evolutionary Model at NASA LaRC is used to demonstrate the effectiveness of the active vibration absorber for vibration suppression. Performance is compared numerically and experimentally using acceleration feedback.

  7. Spacesuit Evaporator-Absorber-Radiator (SEAR)

    NASA Technical Reports Server (NTRS)

    Bue, Grant C.; Hodgson, Ed; Izenso, Mike; Chan, Weibo; Cupples, Scott

    2011-01-01

    For decades advanced spacesuit developers have pursued a regenerable, robust non-venting system for heat rejection. Toward this end, this paper investigates linking together two previously developed technologies, namely NASA's Spacesuit Water Membrane Evaporator (SWME), and Creare's lithium chloride Heat Pump Radiator (HPR). Heat from a liquid cooled garment is transported to SWME that provides cooling through evaporation. The SEAR is evacuated at the onset of operations and thereafter, the water vapor absorption rate of the HPR maintains a low pressure environment for the SWME to evaporate effectively. This water vapor captured by solid LiCl in the HPR with a high enthalpy of absorption, results in sufficient temperature lift to reject most of the heat to space by radiation. After the sortie, the HPR would be heated up in a regenerator to drive off and recover the absorbed evaporant. A one-fourth scale prototype was built and tested in vacuum conditions at a sink temperature of 250 K. The HPR was able to stably reject 60 W over a 7-hour period. A conceptual design of a full-scale radiator is proposed. Excess heat rejection above 240 W would be accomplished through venting of the evaporant. Loop closure rates were predicted for various exploration environment scenarios.

  8. Multifunctional Space Evaporator-Absorber-Radiator (SEAR)

    NASA Technical Reports Server (NTRS)

    Bue, Grant C.; Hodgson, Ed; Izenson, Mike; Chen, Weibo

    2013-01-01

    A system for non-venting thermal control for spacesuits was built by integrating two previously developed technologies, namely NASA's Spacesuit Water Membrane Evaporator (SWME), and Creare's flexible version of the Lithium Chloride Absorber Radiator (LCAR). This SEAR system was tested in relevant thermal vacuum conditions. These tests show that a 1 sq m radiator having about three times as much absorption media as in the test article would be required to support a 7 hour spacewalk. The serial flow arrangement of the LCAR of the flexible version proved to be inefficient for venting non-condensable gas (NCG). A different LCAR packaging arrangement was conceived wherein the Portable Life Support System (PLSS) housing would be made with a high-strength carbon fiber composite honeycomb, the cells of which would be filled with the chemical absorption media. This new packaging reduce the mass and volume impact of the SEAR on the Portable Life Support System (PLSS) compared to the flexible design. A 0.2 sq m panel with flight-like honeycomb geometry is being constructed and will be tested in thermal and thermal vacuum conditions. Design analyses forecast improved system performance and improved NCG control. A flight-like regeneration system also is also being built and tested. Design analyses for the structurally integrated prototype as well as the earlier test data show that SEAR is not only practical for spacesuits but also has useful applications in spacecraft thermal control.

  9. Space Evaporator-Absorber-Radiator (SEAR)

    NASA Technical Reports Server (NTRS)

    Bue, Grant C.; Stephan, Ryan; Hodgson, Ed; Izenson, Mike; Chen, Weibo

    2012-01-01

    A system for non-venting thermal control for spacesuits was built by integrating two previously developed technologies, namely NASA s Spacesuit Water Membrane Evaporator (SWME), and Creare s flexible version of the Lithium Chloride Absorber Radiator (LCAR). This SEAR system was tested in relevant thermal vacuum conditions. These tests show that a 1 m2 radiator having about three times as much absorption media as in the test article would be required to support a 7 hour spacewalk. The serial flow arrangement of the LCAR of the flexible version proved to be inefficient for venting non-condensable gas (NCG). A different LCAR packaging arrangement was conceived wherein the Portable Life Support System (PLSS) housing would be made with a high-strength carbon fiber composite honeycomb, the cells of which would be filled with the chemical absorption media. This new packaging reduces the mass and volume impact of the SEAR on the Portable Life Support System (PLSS) compared to the flexible design. A 0.2 sq m panel with flight-like honeycomb geometry is being constructed and will be tested in thermal and thermal vacuum conditions. Design analyses forecast improved system performance and improved NCG control. A flight-like regeneration system also is also being built and tested. Design analyses for the structurally integrated prototype as well as the earlier test data show that SEAR is not only practical for spacesuits but also has useful applications in spacecraft thermal control.

  10. Design of a multiband terahertz perfect absorber

    NASA Astrophysics Data System (ADS)

    Dan, Hu; Hong-yan, Wang; Zhen-jie, Tang; Xi-wei, Zhang; Lin, Ju; Hua-ying, Wang

    2016-03-01

    A thin-flexible multiband terahertz metamaterial absorber (MA) has been investigated. Each unit cell of the MA consists of a simple metal structure, which includes the top metal resonator ring and the bottom metallic ground plane, separated by a thin-flexible dielectric spacer. Finite-difference time domain simulation indicates that this MA can achieve over 99% absorption at frequencies of 1.50 THz, 3.33 THz, and 5.40 THz by properly assembling the sandwiched structure. However, because of its asymmetric structure, the MA is polarization-sensitive and can tune the absorptivity of the second absorption peak by changing the incident polarization angle. The effect of the error of the structural parameters on the absorption efficiency is also carefully analyzed in detail to guide the fabrication. Moreover, the proposed MA exhibits high refractive-index sensing sensitivity, which has potential applications in multi-wavelength sensing in the terahertz region. Project supported by the National Natural Science Foundation of China (Grant No. 11504006), the Key Scientific Research Project of Higher Education of Henan Province, China (Grant No. 15A140002), and the Science and Technology Planning Project of Henan Province, China (Grant No. 142300410366).

  11. Nonpolynomial Schroedinger equation for resonantly absorbing gratings

    SciTech Connect

    Shabtay, Lior; Malomed, Boris A.

    2011-02-15

    We derive a nonlinear Schroedinger equation with a radical term, {approx}{radical}(1-|V|{sup 2}), as an asymptotic model of the resonantly absorbing Bragg reflector (RABR), i.e., a periodic set of thin layers of two-level atoms, resonantly interacting with the electromagnetic field and inducing the Bragg reflection. A family of bright solitons is found, which splits into stable and unstable parts, exactly obeying the Vakhitov-Kolokolov criterion. The soliton with the largest amplitude, (|V|){sub max}=1, is a ''quasipeakon,'' i.e., a solution with a discontinuity of the third derivative at the center. Families of exact cnoidal waves, built as periodic chains of quasipeakons, are found too. The ultimate solution belonging to the family of dark solitons, with the background level V=1, is a dark compacton. Those bright solitons that are unstable destroy themselves (if perturbed) attaining the critical amplitude, |V|=1. The dynamics of the wave field around this critical point is studied analytically, revealing a switch of the system into an unstable phase, in terms of the RABR model. Collisions between bright solitons are investigated too. The collisions between fast solitons are quasielastic, while slowly moving ones merge into breathers, which may persist or perish (in the latter case, also by attaining |V|=1).

  12. Hot Carrier Extraction with Plasmonic Broadband Absorbers.

    PubMed

    Ng, Charlene; Cadusch, Jasper J; Dligatch, Svetlana; Roberts, Ann; Davis, Timothy J; Mulvaney, Paul; Gómez, Daniel E

    2016-04-26

    Hot charge carrier extraction from metallic nanostructures is a very promising approach for applications in photocatalysis, photovoltaics, and photodetection. One limitation is that many metallic nanostructures support a single plasmon resonance thus restricting the light-to-charge-carrier activity to a spectral band. Here we demonstrate that a monolayer of plasmonic nanoparticles can be assembled on a multistack layered configuration to achieve broadband, near-unit light absorption, which is spatially localized on the nanoparticle layer. We show that this enhanced light absorbance leads to ∼40-fold increases in the photon-to-electron conversion efficiency by the plasmonic nanostructures. We developed a model that successfully captures the essential physics of the plasmonic hot electron charge generation and separation in these structures. This model also allowed us to establish that efficient hot carrier extraction is limited to spectral regions where (i) the photons have energies higher than the Schottky junctions and (ii) the absorption of light is localized on the metal nanoparticles. PMID:26982625

  13. Semiconductor nanowire optical antenna solar absorbers.

    PubMed

    Cao, Linyou; Fan, Pengyu; Vasudev, Alok P; White, Justin S; Yu, Zongfu; Cai, Wenshan; Schuller, Jon A; Fan, Shanhui; Brongersma, Mark L

    2010-02-10

    Photovoltaic (PV) cells can serve as a virtually unlimited clean source of energy by converting sunlight into electrical power. Their importance is reflected in the tireless efforts that have been devoted to improving the electrical and structural properties of PV materials. More recently, photon management (PM) has emerged as a powerful additional means to boost energy conversion efficiencies. Here, we demonstrate an entirely new PM strategy that capitalizes on strong broad band optical antenna effects in one-dimensional semiconductor nanostructures to dramatically enhance absorption of sunlight. We show that the absorption of sunlight in Si nanowires (Si NWs) can be significantly enhanced over the bulk. The NW's optical properties also naturally give rise to an improved angular response. We propose that by patterning the silicon layer in a thin film PV cell into an array of NWs, one can boost the absorption for solar radiation by 25% while utilizing less than half of the semiconductor material (250% increase in the light absorption per unit volume of material). These results significantly advance our understanding of the way sunlight is absorbed by one-dimensional semiconductor nanostructures and provide a clear, intuitive guidance for the design of efficient NW solar cells. The presented approach is universal to any semiconductor and a wide range of nanostructures; as such, it provides a new PV platform technology. PMID:20078065

  14. ON THE LINK BETWEEN ASSOCIATED Mg II ABSORBERS AND STAR FORMATION IN QUASAR HOSTS

    SciTech Connect

    Shen Yue; Menard, Brice E-mail: menard@pha.jhu.edu

    2012-04-01

    A few percent of quasars show strong associated Mg II absorption, with velocities (v{sub off}) lying within a few thousand km s{sup -1} from the quasar systemic redshift. These associated absorption line (AAL) systems are usually interpreted as absorbers that are either intrinsic to the quasar and its host, or arising from external galaxies clustering around the quasar. Using composite spectra of {approx}1800 Mg II AAL quasars selected from SDSS DR7 at 0.4 {approx}< z {approx}< 2, we show that quasars with AALs with v{sub off} < 1500 km s{sup -1} have a prominent excess in [O II] {lambda}3727 emission (detected at >7{sigma}) at rest relative to the quasar host, compared to unabsorbed quasars. We interpret this [O II] excess as due to enhanced star formation in the quasar host. Our results suggest that a significant fraction of AALs with v{sub off} < 1500 km s{sup -1} are physically associated with the quasar and its host. AAL quasars also have dust reddening lying between normal quasars and the so-called dust-reddened quasars. We suggest that the unique properties of AAL quasars can be explained if they are the transitional population from heavily dust-reddened quasars to normal quasars in the formation process of quasars and their hosts. This scenario predicts a larger fraction of young bulges, disturbed morphologies, and interactions of AAL quasar hosts compared to normal quasars. The intrinsic link between associated absorbers and quasar hosts opens a new window to probe massive galaxy formation and galactic-scale feedback processes, and provides a crucial test of the evolutionary picture of quasars.

  15. NuSTAR and XMM-Newton Observations of Luminous, Heavily Obscured, WISE-selected Quasars at z ~ 2

    NASA Astrophysics Data System (ADS)

    Stern, D.; Lansbury, G. B.; Assef, R. J.; Brandt, W. N.; Alexander, D. M.; Ballantyne, D. R.; Baloković, M.; Bauer, F. E.; Benford, D.; Blain, A.; Boggs, S. E.; Bridge, C.; Brightman, M.; Christensen, F. E.; Comastri, A.; Craig, W. W.; Del Moro, A.; Eisenhardt, P. R. M.; Gandhi, P.; Griffith, R. L.; Hailey, C. J.; Harrison, F. A.; Hickox, R. C.; Jarrett, T. H.; Koss, M.; Lake, S.; LaMassa, S. M.; Luo, B.; Tsai, C.-W.; Urry, C. M.; Walton, D. J.; Wright, E. L.; Wu, J.; Yan, L.; Zhang, W. W.

    2014-10-01

    We report on a NuSTAR and XMM-Newton program that has observed a sample of three extremely luminous, heavily obscured WISE-selected active galactic nuclei (AGNs) at z ~ 2 across a broad X-ray band (0.1 - 79 keV). The parent sample, selected to be faint or undetected in the WISE 3.4 μm (W1) and 4.6 μm (W2) bands but bright at 12 μm (W3) and 22 μm (W4), are extremely rare, with only ~1000 so-called "W1W2-dropouts" across the extragalactic sky. Optical spectroscopy reveals typical redshifts of z ~ 2 for this population, implying rest-frame mid-IR luminosities of νL ν(6 μm) ~ 6 × 1046 erg s-1 and bolometric luminosities that can exceed L bol ~ 1014 L ⊙. The corresponding intrinsic, unobscured hard X-ray luminosities are L(2-10 keV) ~ 4 × 1045 erg s-1 for typical quasar templates. These are among the most AGNs known, though the optical spectra rarely show evidence of a broad-line region and the selection criteria imply heavy obscuration even at rest-frame 1.5 μm. We designed our X-ray observations to obtain robust detections for gas column densities N H <= 1024 cm-2. In fact, the sources prove to be fainter than these predictions. Two of the sources were observed by both NuSTAR and XMM-Newton, with neither being detected by NuSTAR (f 3-24 keV <~ 10-13 erg cm-2 s-1), and one being faintly detected by XMM-Newton (f 0.5-10 keV ~ 5 × 10-15 erg cm-2 s-1). A third source was observed only with XMM-Newton, yielding a faint detection (f 0.5-10 keV ~ 7 × 10-15 erg cm-2 s-1). The X-ray data imply these sources are either X-ray weak, or are heavily obscured by column densities N H >~ 1024 cm-2. The combined X-ray and mid-IR analysis seems to favor this second possibility, implying the sources are extremely obscured, consistent with Compton-thick, luminous quasars. The discovery of a significant population of heavily obscured, extremely luminous AGNs would not conform to the standard paradigm of a receding torus, in which more luminous quasars are less likely to be

  16. Characterization of the heavily doped emitter and junction regions of silicon solar cells using an electron beam

    NASA Technical Reports Server (NTRS)

    Luke, K. L.; Cheng, L.-J.

    1986-01-01

    Heavily doped emitter and junction regions of silicon solar cells are investigated by means of the electron-beam-induced-current (EBIC) technique. Although the experimental EBIC data are collected under three-dimensional conditions, it is analytically demonstrated with two numerical examples that the solutions obtained with one-dimensional numerical modeling are adequate. EBIC data for bare and oxide-covered emitter surfaces are compared with theory. The improvement in collection efficiency when an emitter surface is covered with a 100-A SiO2 film varies with beam energy; for a cell with a junction depth of 0.35 microns, the improvement is about 54 percent at 2 keV.

  17. Superconducting properties in heavily overdoped Ba(Fe0.86Co0.14)2As2 single crystals

    NASA Astrophysics Data System (ADS)

    Kim, Jeehoon; Haberkorn, N.; Gofryk, K.; Graf, M. J.; Ronning, F.; Sefat, A. S.; Movshovich, R.; Civale, L.

    2015-01-01

    We report the intrinsic superconducting parameters in a heavily overdoped Ba(Fe1-xCox)2As2 (x=0.14) single crystal and their influence in the resulting vortex dynamics. We find a bulk superconducting critical temperature of 9.8 K, magnetic penetration depth λab (0)=660±50 nm, coherence length ξab (0)=6.4±0.2 nm, and the upper critical field anisotropy γT→Tc≈3.7. The vortex phase diagram, in comparison with the optimally doped compound, presents a narrow collective creep regime. The intrinsic pinning energy plays an important role in the resulting vortex dynamics as compared with similar pinning landscape and comparable intrinsic thermal fluctuations.

  18. Hopping conduction range of heavily Al-doped 4H-SiC thick epilayers grown by CVD

    NASA Astrophysics Data System (ADS)

    Ji, Shiyang; Eto, Kazuma; Yoshida, Sadafumi; Kojima, Kazutoshi; Ishida, Yuuki; Saito, Shingo; Tsuchida, Hidekazu; Okumura, Hajime

    2015-12-01

    To outline the hopping conduction range, the electrical characteristics of CVD-grown heavily Al-doped 4H-SiC thick epilayers (2.0 × 1019-4.0 × 1020 cm-3) were investigated in a wide temperature regime (20-900 K). It is found that, below 100 K, hopping conduction dominates the carrier transport for all epilayers, and the corresponding hopping conduction activation energy shows a maximum of ˜30 meV at around 1.1 × 1020 cm-3. With increasing doping level, the temperature dependence of resistivity evolves and finally obeys the ˜1/T1/4 law in the entire temperature regime, which gives direct evidence of variable-range hopping conduction.

  19. Mars Crustal Remanent Magnetism: An Extinct Dynamo Leaves a Record of Field Reversals in the Heavily Cratered Highlands

    NASA Technical Reports Server (NTRS)

    Connerney, John E.; Acuna, Mario H.; Ness, Norman F.; Wasilewski, Peter J.

    1999-01-01

    The Mars Global Surveyor spacecraft, in a highly elliptical polar orbit about Mars, obtained vector magnetic field measurements just above the surface of Mars (altitudes > 100 kilometers). Crustal magnetization, largely confined to the most ancient, heavily cratered Mars highlands, is frequently organized in east-west trending linear features, the largest of which extends over 2000 km. A representative set of survey passes are modeled using uniformly magnetized thin plates and a generalized inverse methodology. Crustal remanent magnetization exceeds that deduced for the largest terrestrial magnetic anomalies by more than an order of magnitude. Groups of quasi-parallel linear features of alternating magnetic polarity are found. They are reminiscent of similar magnetic features associated with sea floor spreading and crustal genesis on Earth but with a much larger spatial scale.

  20. Electron transport behaviors through donor-induced quantum dot array in heavily n-doped junctionless nanowire transistors

    SciTech Connect

    Ma, Liuhong; Han, Weihua Wang, Hao; Hong, Wenting; Lyu, Qifeng; Yang, Xiang; Yang, Fuhua

    2015-01-21

    We investigated single electron tunneling through a phosphorus donor-induced quantum dot array in heavily n-doped junctionless nanowire transistor. Seven subpeaks splitting in current oscillations are clearly observed due to the coupling of quantum dot array under the bias voltage below 1.0 mV at the temperature of 6 K. The conduction system can be well described by a two-band Hubbard model. The activation energy of phosphorus donors is tuned by the gate voltage to be 7.0 meV for the lower Hubbard band and 4.4 meV for the upper Hubbard band due to the localization effects below threshold voltage. The evolution of electron behaviors in the quantum dots is identified by adjusting the gate voltage from quantum-dot regime to one-dimensional regime.

  1. Electron transport behaviors through donor-induced quantum dot array in heavily n-doped junctionless nanowire transistors

    NASA Astrophysics Data System (ADS)

    Ma, Liuhong; Han, Weihua; Wang, Hao; Hong, Wenting; Lyu, Qifeng; Yang, Xiang; Yang, Fuhua

    2015-01-01

    We investigated single electron tunneling through a phosphorus donor-induced quantum dot array in heavily n-doped junctionless nanowire transistor. Seven subpeaks splitting in current oscillations are clearly observed due to the coupling of quantum dot array under the bias voltage below 1.0 mV at the temperature of 6 K. The conduction system can be well described by a two-band Hubbard model. The activation energy of phosphorus donors is tuned by the gate voltage to be 7.0 meV for the lower Hubbard band and 4.4 meV for the upper Hubbard band due to the localization effects below threshold voltage. The evolution of electron behaviors in the quantum dots is identified by adjusting the gate voltage from quantum-dot regime to one-dimensional regime.

  2. Response to eribulin in a difficult-to-treat, heavily pretreated breast cancer patient: a case report.

    PubMed

    Leo, Luigi; Caputo, Francesca; Sarno, Antonella Di; Garofano, Tiziana; Andreozzi, Francesca; Massaro, Maria Grazia; Montesarchio, Vincenzo

    2015-01-01

    In this short paper, we report our experience with eribulin mesylate in a heavily pretreated breast cancer patient with multiple bone metastases. The patient had been treated with doxorubicin, cyclophosphamide, methotrexate, fluorouracil, tamoxifen, letrozole, LH-RH analogs, fulvestrant, bevacizumab and paclitaxel and liposomal doxorubicin. In November 2013 treatment with eribulin ready to use solution (1.23 mg/m(2) days 1 and 8 of a 21-day cycle) was started and administered for a total of 14 courses. After six cycles of eribulin, evaluation with MRI showed a marked decrease in neoplastic involvement and replacement of osteolytic lesions with osteoblastic ones. No unexpected acute toxicity was observed. Although with all the limitations of any anecdotal report, our experience documents the efficacy and safety of eribulin in this difficult-to-treat patient who had been treated with multiple lines of chemotherapy. PMID:26235262

  3. The role of potential fluctuations in continuous-wave donor{endash}acceptor pair luminescence of heavily doped materials

    SciTech Connect

    Kuskovsky, I.; Li, D.; Neumark, G.F.; Bondarev, V.N.; Pikhitsa, P.V.

    1999-08-01

    It has recently become apparent that {open_quotes}standard{close_quotes} (low-concentration and low-compensation) theory for donor{endash}acceptor pair (DAP) photoluminescence (PL) is totally incapable of explaining results in highly doped and compensated material. It can be noted that such material is often of high technological interest. It has been argued, mainly qualitatively, that the discrepancies result from potential fluctuations due to random ionic charges. We here present a {ital quantitative} theory for cw DAP PL, using an approximate model. We also present data for the concentration and intensity dependence of DAP PL in heavily doped ZnSe:N, and show that the results are explained very satisfactorily by our fluctuation model. {copyright} {ital 1999 American Institute of Physics.}

  4. Evolution of magnetic phase at low aging temperature in a heavily cold-drawn stainless steel fiber

    NASA Astrophysics Data System (ADS)

    Yang, Shun-Tung; Hwang, Weng-Sing; Shyr, Tien-Wei; Cheng, I.-Lin

    2012-08-01

    The evolution of the magnetic phase upon aging at 300-520 °C in a heavily cold-drawn AISI 316L austenitic stainless steel fiber was studied using thermomagnetic analysis (TMA) and magnetic force microscopy with a heating stage. An increasing trend of magnetization from 50 °C to around 470 °C in the heating curves of TMA in austenitic stainless steels after a cold-drawing process was observed. No significant Ms temperature signal in the TMA curve at cooling indicated an increase in magnetization upon cooling period without significant phase transformation. A series of in situ magnetic force microscopy observations reveal a growth of the magnetic domain structure after aging at 300 °C for 2.5 h. Results show that the ferromagnetic increase during aging at lower annealing temperature resulted from the growth of martensite.

  5. Roadside suspended particulates at heavily trafficked urban sites of Hong Kong - Seasonal variation and dependence on meteorological conditions

    NASA Astrophysics Data System (ADS)

    Chan, L. Y.; Kwok, W. S.

    In this study, the seasonal variation of different types of particulates was investigated in a fixed roadside station in heavily trafficked urban area of Hong Kong. Aerosol samples for total suspended particles (TSP), PM 10 and PM 2.5 were collected from June 1998 to May 1999 at a roadside site. Meteorological conditions such as relative humidity (RH), rainfall and prevailing wind direction were found to affect the mass concentration of TSP, PM 10 and coarse particulates at roadside level. Large size particles had an apparent seasonal variation, with higher concentration level in winter and lower in summer. The dry continental winter monsoon and the wet oceanic summer monsoon are the dominating factors. On the other hand, annual variation of PM 2.5 is relatively insignificant, suggesting that they are mainly from local traffic emission. PM 10 accounted for 62% of the TSP, while PM 2.5 accounted for 46%. The annual PM 2.5/PM 10 is high with PM 2.5 responsible for 74% of PM 10. In our heavily trafficked roadside fixed site, TSP exceeded the annual average of the Hong Kong Air Quality Objective by a factor of 1.53 while PM 10 exceeded by 1.39. The annual average concentration of PM 2.5 exceeded the National Ambient Air Quality Standard (NAAQS) annual average of 15 μg m -3 by a factor of 3.8 and is a cause of concern. A total of the 24 h average PM 2.5 exceeded NAAQS by 33%. According to our data reported, fine particulate pollution is serious in Hong Kong.

  6. Clinical Outcomes of Patients with Rare and Heavily Pretreated Solid Tumors Treated according to the Results of Tumor Molecular Profiling

    PubMed Central

    Hayden, Ingrid

    2016-01-01

    Patients with heavily pretreated advanced cancer or with rare tumors are difficult to treat. Molecular profiling (MP) of tumors to identify biomarkers that predict potential outcomes with individual therapies is an emerging strategy to guide treatment decisions. Patients with rare tumors for which standard-of-care therapy was unavailable or more common tumors for which standard-of-care options had been exhausted underwent MP at a single Australian center. Data regarding treating physicians' choice of therapy, MP results and recommendations, and patient outcomes were collected. Seven patients had received prior standard first-line therapy (PST), 16 had rare tumors, and 31 had been heavily pretreated (HPT; ≥2 prior lines). Most treatments suggested by MP (541/594; 91.1%) were common chemotherapy drugs available in generic formulations. MP-guided therapy recommendations differed from physician's recommendations in 48 patients (88.9%). MP-guided therapy produced clinical benefit (improved QOL and/or performance status, symptoms, bodyweight, or RECIST) in 19/31 (61.3%), 11/16 (68.8%), and 3/7 (42.9%) patients with HPTs, rare tumors, and PSTs, respectively, and had a PFS ratio ≥1.3 in 22/37 evaluable patients (59.5%; 95% confidence interval 44–76%). The null hypothesis that ≤15% of these patients would have a PFS ratio ≥1.3 was rejected (one-sided p < 0.0001). In conclusion, using MP to guide therapy selection is feasible in clinical practice and may improve patient outcomes. PMID:27525268

  7. Preliminary Results From a Heavily Instrumented Engine Ice Crystal Icing Test in a Ground Based Altitude Test Facility

    NASA Technical Reports Server (NTRS)

    Flegel, Ashlie B.; Oliver, Michael J.

    2016-01-01

    Preliminary results from the heavily instrumented ALF502R-5 engine test conducted in the NASA Glenn Research Center Propulsion Systems Laboratory are discussed. The effects of ice crystal icing on a full scale engine is examined and documented. This same model engine, serial number LF01, was used during the inaugural icing test in the Propulsion Systems Laboratory facility. The uncommanded reduction of thrust (rollback) events experienced by this engine in flight were simulated in the facility. Limited instrumentation was used to detect icing on the LF01 engine. Metal temperatures on the exit guide vanes and outer shroud and the load measurement were the only indicators of ice formation. The current study features a similar engine, serial number LF11, which is instrumented to characterize the cloud entering the engine, detect/characterize ice accretion, and visualize the ice accretion in the region of interest. Data were acquired at key LF01 test points and additional points that explored: icing threshold regions, low altitude, high altitude, spinner heat effects, and the influence of varying the facility and engine parameters. For each condition of interest, data were obtained from some selected variations of ice particle median volumetric diameter, total water content, fan speed, and ambient temperature. For several cases the NASA in-house engine icing risk assessment code was used to find conditions that would lead to a rollback event. This study further helped NASA develop necessary icing diagnostic instrumentation, expand the capabilities of the Propulsion Systems Laboratory, and generate a dataset that will be used to develop and validate in-house icing prediction and risk mitigation computational tools. The ice accretion on the outer shroud region was acquired by internal video cameras. The heavily instrumented engine showed good repeatability of icing responses when compared to the key LF01 test points and during day-to-day operation. Other noticeable

  8. Heavily reddened z ˜ 2 Type 1 quasars - II. H α star formation constraints from SINFONI IFU observations

    NASA Astrophysics Data System (ADS)

    Alaghband-Zadeh, S.; Banerji, Manda; Hewett, Paul C.; McMahon, Richard G.

    2016-06-01

    We use near-infrared integral field unit spectroscopy to search for H α emission associated with star formation in a sample of 28 heavily reddened (E(B - V) ≃ 0.5-1.9), hyperluminous (log({{L}}_{bol}/erg s^{-1})≃ 47-48) broad-line quasars at z ≃ 1.4-2.7. 16 of the 28 quasars show evidence for star formation with an average extinction-corrected star formation rate (SFR) of 320 ± 70 M⊙ yr-1. A stacked spectrum of the detections shows weak [N II], consistent with star formation as the origin of the narrow H α emission. The star-forming regions are spatially unresolved in 11 of the 16 detections and constrained to lie within ˜6 kpc of the quasar emission. In the five resolved detections we find the star-forming regions are extended on scales of ˜8 kpc around the quasar emission. The prevalence of high SFRs is consistent with the identification of the heavily reddened quasar population as representing a transitional phase from apparent `starburst galaxies' to optically luminous quasars. Upper limits are determined for 10 quasars in which star formation is undetected. In two of the quasars the SFR is constrained to be relatively modest, <50 M⊙ yr-1, but significantly higher levels of star formation could be present in the other eight quasars. The combination of the 16 strong star formation detections and the eight high SFR limits means that high levels of star formation may be present in the majority of the sample. Higher spatial resolution data, of multiple emission lines, will allow us to better understand the interplay between star formation and active galactic nucleus activity in these transitioning quasars.

  9. Clinical Outcomes of Patients with Rare and Heavily Pretreated Solid Tumors Treated according to the Results of Tumor Molecular Profiling.

    PubMed

    Dean, Andrew; Byrne, Aisling; Marinova, Mira; Hayden, Ingrid

    2016-01-01

    Patients with heavily pretreated advanced cancer or with rare tumors are difficult to treat. Molecular profiling (MP) of tumors to identify biomarkers that predict potential outcomes with individual therapies is an emerging strategy to guide treatment decisions. Patients with rare tumors for which standard-of-care therapy was unavailable or more common tumors for which standard-of-care options had been exhausted underwent MP at a single Australian center. Data regarding treating physicians' choice of therapy, MP results and recommendations, and patient outcomes were collected. Seven patients had received prior standard first-line therapy (PST), 16 had rare tumors, and 31 had been heavily pretreated (HPT; ≥2 prior lines). Most treatments suggested by MP (541/594; 91.1%) were common chemotherapy drugs available in generic formulations. MP-guided therapy recommendations differed from physician's recommendations in 48 patients (88.9%). MP-guided therapy produced clinical benefit (improved QOL and/or performance status, symptoms, bodyweight, or RECIST) in 19/31 (61.3%), 11/16 (68.8%), and 3/7 (42.9%) patients with HPTs, rare tumors, and PSTs, respectively, and had a PFS ratio ≥1.3 in 22/37 evaluable patients (59.5%; 95% confidence interval 44-76%). The null hypothesis that ≤15% of these patients would have a PFS ratio ≥1.3 was rejected (one-sided p < 0.0001). In conclusion, using MP to guide therapy selection is feasible in clinical practice and may improve patient outcomes. PMID:27525268

  10. Absorbable microparticulate cation exchanger for immunotherapeutic delivery.

    PubMed

    Shalaby, Waleed S W; Yeh, Heidi; Woo, Edward; Corbett, Joel T; Gray, Heidi; June, Carl H; Shalaby, Shalaby W

    2004-05-15

    An absorbable microparticulate cation exchanger was synthesized as a versatile carrier for biologically active proteins. In this work, acid-terminated polyglycolide (or polyglycolic acid) microparticulates (PG-MP) were surface modified for either sustained release of cytokines or as a platform for immunomodulation. The intended goal was to achieve in situ recruitment/maturation of dendritic cells and activation of T cells for tumor immunotherapy. PG-MP were prepared with a volume weighted mean diameter of 7.02 micro (range: 2.09-14.58 micro). Accessible carboxylic acid groups were determined to be 0.3 mmol/g with a corresponding zeta potential of -21.87 mV in phosphate-buffered saline. Under low magnification, scanning electron microscopy (SEM) revealed a highly textured surface due to processing from repetitive jet milling. However, a moderately porous architecture was noted at higher magnification. Electron spectroscopy for chemical analysis was used to characterize the PG-MP surface before and after adsorption of human granulocyte-macrophage colony stimulating factor (GM-CSF). Adsorption of GM-CSF on PG-MP (PG-GMCSF) resulted in a modest increase in the surface atomic concentration of nitrogen (0.97%). Pretreating the surface with poly-L-lysine (PG/Lys-GMCSF) prior to adding GM-CSF produced a nearly threefold increase in the surface nitrogen concentration (4.20% compared to 1.47%). This manipulation not only increased loading content, but also prolonged the release of GM-CSF released from 6 days to 26 days. ESCA on the post-release PG-MP samples (PG-GMCSF and PG/Lys-GMCSF) revealed a similar residual surface nitrogen concentration (2.26% vs. 2.35%). The observation was consistent with irreversibly adsorbed GM-CSF. It is postulated that irreversibly bound GM-CSF is released over time as a function of microparticulate degradation. Biological activity of released GM-CSF was confirmed by the proliferation of a GM-CSF-dependent cell line (TF-1) in the presence of

  11. 21 CFR 878.4490 - Absorbable hemostatic agent and dressing.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Absorbable hemostatic agent and dressing. 878.4490 Section 878.4490 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES GENERAL AND PLASTIC SURGERY DEVICES Surgical Devices § 878.4490 Absorbable hemostatic agent and dressing....

  12. 21 CFR 878.4490 - Absorbable hemostatic agent and dressing.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Absorbable hemostatic agent and dressing. 878.4490 Section 878.4490 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES GENERAL AND PLASTIC SURGERY DEVICES Surgical Devices § 878.4490 Absorbable hemostatic agent and dressing....

  13. 21 CFR 880.6025 - Absorbent tipped applicator.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Absorbent tipped applicator. 880.6025 Section 880.6025 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED... device intended for medical purposes that consists of an absorbent swab on a wooden, paper, or...

  14. Excitable solitons in a semiconductor laser with a saturable absorber

    NASA Astrophysics Data System (ADS)

    Turconi, Margherita; Prati, Franco; Barland, Stéphane; Tissoni, Giovanna

    2015-11-01

    Self-pulsing cavity solitons may exist in a semiconductor laser with an intracavity saturable absorber. They show locally the passive Q -switching behavior that is typical of lasers with saturable absorbers in the plane-wave approximation. Here we show that excitable cavity solitons are also possible in a suitable parameter range and characterize their excitable dynamics and properties.

  15. 21 CFR 880.6025 - Absorbent tipped applicator.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Absorbent tipped applicator. 880.6025 Section 880.6025 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES GENERAL HOSPITAL AND PERSONAL USE DEVICES General Hospital and Personal Use Miscellaneous Devices § 880.6025 Absorbent...

  16. 40 CFR 65.150 - Absorbers used as control devices.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... parts per million by volume outlet concentration requirements as specified in § 65.63(a)(2), or 40 CFR... control device on a Group 1 process vent or a high-throughput transfer rack with an absorber used as a... 40 Protection of Environment 15 2011-07-01 2011-07-01 false Absorbers used as control devices....

  17. 40 CFR 65.150 - Absorbers used as control devices.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... parts per million by volume outlet concentration requirements as specified in § 65.63(a)(2), or 40 CFR... control device on a Group 1 process vent or a high-throughput transfer rack with an absorber used as a... 40 Protection of Environment 15 2010-07-01 2010-07-01 false Absorbers used as control devices....

  18. Photochromic And Thermochromic Pigments For Solar Absorbing-Reflecting Coatings

    NASA Astrophysics Data System (ADS)

    Novinson, Thomas

    1987-11-01

    Both photochromic and thermochromic compounds were synthesized and physical measurements were made to determine coefficients of relectance, absorbance and emission. The most interesting group of thermochromic compounds are related to silver tctraiodomercurate and the most interesting photochromic compounds are substituted benzoindolinopyrospirans. The synthesis and optical reflectance and absorbance properties of other classes of compounds are also reported.

  19. 21 CFR 878.4490 - Absorbable hemostatic agent and dressing.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Absorbable hemostatic agent and dressing. 878.4490 Section 878.4490 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... hemostatic agent and dressing. (a) Identification. An absorbable hemostatic agent or dressing is a...

  20. An adaptive tuned vibration absorber based on multilayered MR elastomers

    NASA Astrophysics Data System (ADS)

    Sun, Shuaishuai; Deng, Huaxia; Yang, Jian; Li, Weihua; Du, Haiping; Alici, Gursel; Nakano, Masami

    2015-04-01

    Adaptive tuned vibration absorbers (ATVAs) featuring magnetorheological elastomers (MREs) have attracted considerable research interests because of the advantages of fast response, controllable frequency, and broad working range. Generally, the ATVA uses single layer of MRE sheet, which has some issues such as small oscillator stroke and being effective only on high frequency. In this research, an ATVA which incorporates multilayer MRE sheets was designed and prototyped. Its performance under various scan frequencies was tested on a horizontal vibration platform. A theoretical model was proposed to predict the MRE absorber performance. For the clear demonstration of the advantages of multilayered MRE absorber, two kinds of absorbers with only one layer of MRE were prepared as comparison. The experiments compared the vertical support capability and the tuning frequency range of these two ATVAs, which have clearly highlighted the capabilities of multilayered MRE absorber with larger oscillator stroke (as large as 13.6 mm) and lower working frequencies (as low as 3.2 Hz). The vibration absorption evaluation was conducted by mounting the multilayered MRE absorber on a single-degree-of-freedom system. The results identify that the ATVA with multilayered MREs could work lower than 10 Hz, which is very difficult for the one with single layer MRE. Additionally, the performance of the passive and adaptive tuned laminated MRE absorbers on attenuating a swept frequency vibration are presented, respectively. The ATVA was more effective than the passive absorber over a wide frequency range.

  1. 21 CFR 878.4830 - Absorbable surgical gut suture.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Absorbable surgical gut suture. 878.4830 Section 878.4830 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES GENERAL AND PLASTIC SURGERY DEVICES Surgical Devices § 878.4830 Absorbable surgical gut suture. (a) Identification. An...

  2. Science on a Roll. Part One: Absorbing Inquiry.

    ERIC Educational Resources Information Center

    Brendzel, Sharon

    2002-01-01

    Presents an activity that tests the absorbency of different brands of paper towels. Suggests making this activity into an open-ended inquiry type of activity. Includes sample questions to guide students, topics for class discussion, and sample methods of using the absorbency activity. (KHR)

  3. 14 CFR 29.475 - Tires and shock absorbers.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Tires and shock absorbers. 29.475 Section... AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Strength Requirements Ground Loads § 29.475 Tires and shock absorbers. Unless otherwise prescribed, for each specified landing condition, the tires must...

  4. 14 CFR 29.475 - Tires and shock absorbers.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Tires and shock absorbers. 29.475 Section... AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Strength Requirements Ground Loads § 29.475 Tires and shock absorbers. Unless otherwise prescribed, for each specified landing condition, the tires must...

  5. 14 CFR 27.475 - Tires and shock absorbers.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Tires and shock absorbers. 27.475 Section... AIRWORTHINESS STANDARDS: NORMAL CATEGORY ROTORCRAFT Strength Requirements Ground Loads § 27.475 Tires and shock absorbers. Unless otherwise prescribed, for each specified landing condition, the tires must be assumed...

  6. 14 CFR 27.475 - Tires and shock absorbers.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Tires and shock absorbers. 27.475 Section... AIRWORTHINESS STANDARDS: NORMAL CATEGORY ROTORCRAFT Strength Requirements Ground Loads § 27.475 Tires and shock absorbers. Unless otherwise prescribed, for each specified landing condition, the tires must be assumed...

  7. 14 CFR 29.475 - Tires and shock absorbers.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Tires and shock absorbers. 29.475 Section... AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Strength Requirements Ground Loads § 29.475 Tires and shock absorbers. Unless otherwise prescribed, for each specified landing condition, the tires must...

  8. 14 CFR 29.475 - Tires and shock absorbers.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Tires and shock absorbers. 29.475 Section... AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Strength Requirements Ground Loads § 29.475 Tires and shock absorbers. Unless otherwise prescribed, for each specified landing condition, the tires must...

  9. 14 CFR 27.475 - Tires and shock absorbers.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Tires and shock absorbers. 27.475 Section... AIRWORTHINESS STANDARDS: NORMAL CATEGORY ROTORCRAFT Strength Requirements Ground Loads § 27.475 Tires and shock absorbers. Unless otherwise prescribed, for each specified landing condition, the tires must be assumed...

  10. 14 CFR 27.475 - Tires and shock absorbers.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Tires and shock absorbers. 27.475 Section... AIRWORTHINESS STANDARDS: NORMAL CATEGORY ROTORCRAFT Strength Requirements Ground Loads § 27.475 Tires and shock absorbers. Unless otherwise prescribed, for each specified landing condition, the tires must be assumed...

  11. 14 CFR 29.475 - Tires and shock absorbers.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Tires and shock absorbers. 29.475 Section... AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Strength Requirements Ground Loads § 29.475 Tires and shock absorbers. Unless otherwise prescribed, for each specified landing condition, the tires must...

  12. 14 CFR 27.475 - Tires and shock absorbers.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Tires and shock absorbers. 27.475 Section... AIRWORTHINESS STANDARDS: NORMAL CATEGORY ROTORCRAFT Strength Requirements Ground Loads § 27.475 Tires and shock absorbers. Unless otherwise prescribed, for each specified landing condition, the tires must be assumed...

  13. An Absorbing Look at Terry-Cloth Towels

    ERIC Educational Resources Information Center

    Moyer, Richard; Everett, Susan

    2010-01-01

    This article describes a lesson where students explore the absorbency of several towels with different weaves and weights. The lesson follows the 5E learning-cycle model and incorporates engineering in the sense of product testing with a focus on the relationship between the weave of a towel and its absorbency. The National Science Education…

  14. Nylon shock absorber prevents injury to parachute jumpers

    NASA Technical Reports Server (NTRS)

    Mandel, J. A.

    1966-01-01

    Nylon shock absorbers reduce the canopy-opening shock of a parachute to a level that protects the wearer from injury. A shock absorber is mounted on each of the four risers between the shroud lines and the harness. Because of their size and location, they pose no problem in repacking the chute and harness after a jump.

  15. Performance of an artificial absorber for truncating FEM meshes

    NASA Astrophysics Data System (ADS)

    Gong, Jian; Volakis, John L.

    1995-01-01

    We investigate the effectiveness of an artificial absorber for truncating finite element (FE) meshes. Specifically, we present the implementation of a novel mesh truncation approach using a perfectly matched anisotropic absorber for waveguides and stripline circuits. This truncation scheme is useful in many applications, including antennas, scattering, and microwave circuits.

  16. Physically absorbable reagents-collectors in elementary flotation

    SciTech Connect

    S.A. Kondrat'ev; I.G. Bochkarev

    2007-09-15

    Based on the reviewed researches held at the Institute of Mining, Siberian Branch, Russian Academy of Sciences, the effect of physically absorbable reagents-collectors on formation of a flotation complex and its stability in turbulent pulp flows in flotation machines of basic types is considered. The basic requirements for physically absorbable reagents-collectors at different flotation stages are established.

  17. Towards absorbing outer boundaries in general relativity

    NASA Astrophysics Data System (ADS)

    Buchman, Luisa T.; Sarbach, Olivier C. A.

    2006-12-01

    We construct exact solutions to the Bianchi equations on a flat spacetime background. When the constraints are satisfied, these solutions represent in- and outgoing linearized gravitational radiation. We then consider the Bianchi equations on a subset of flat spacetime of the form [0, T] × BR, where BR is a ball of radius R, and analyse different kinds of boundary conditions on ∂BR. Our main results are as follows. (i) We give an explicit analytic example showing that boundary conditions obtained from freezing the incoming characteristic fields to their initial values are not compatible with the constraints. (ii) With the help of the exact solutions constructed, we determine the amount of artificial reflection of gravitational radiation from constraint-preserving boundary conditions which freeze the Weyl scalar Ψ0 to its initial value. For monochromatic radiation with wave number k and arbitrary angular momentum number ell >= 2, the amount of reflection decays as (kR)-4 for large kR. (iii) For each L >= 2, we construct new local constraint-preserving boundary conditions which perfectly absorb linearized radiation with ell <= L. (iv) We generalize our analysis to a weakly curved background of mass M and compute first-order corrections in M/R to the reflection coefficients for quadrupolar odd-parity radiation. For our new boundary condition with L = 2, the reflection coefficient is smaller than that for the freezing Ψ0 boundary condition by a factor of M/R for kR > 1.04. Implications of these results for numerical simulations of binary black holes on finite domains are discussed.

  18. Ultra-broadband plasmonic super absorbers for universal surface enhanced Raman spectroscopy substrate (Presentation Recording)

    NASA Astrophysics Data System (ADS)

    Zhang, Nan; Liu, Kai; Song, Haomin; Zeng, Xie; Ji, Dengxin; Gan, Qiaoqiang

    2015-08-01

    Although Raman spectroscopy has been commercialized, low-cost and large-area surface enhanced Raman spectroscopy (SERS) substrates with localized enhanced field are heavily required. However, currently dominant manufacturing techniques are expensive and complicated for large-area fabrication. Furthermore, most SERS substrates can only be used for individual excitation wavelengths. In this work, we will report an ultra-broadband super absorbing metasurface to enhance SERS signals in a broadband region (i.e. from 450 nm to 1000 nm). The design consisting of an Ag ground plate, a SiO2 spacer, and a layer of Ag nanoparticles was fabricated using simple film deposition and thermal annealing techniques. A broadband absorption over 80% from 414 nm to 956 nm was obtained, resulting in localized field enhancement between adjacent nanoparticles. We employed this metasurface to test its broadband SERS signal by adsorbing 1,2-Bis(4-pyridyl)-ethylene (BPE) molecules on top of it. We employed 5 laser lines (i.e., 514, 532, 633, 671 and 785 nm) to excite the sample and observed fingerprint signature of BPE molecules under all 5 excitation wavelengths with the average enhancement factor up to 5.3×107. Therefore, the designed SERS substrate can work for almost "all" available excitation wavelengths over a broadband, which is particularly useful for sensing a broad spectrum of chemicals on the same chip.

  19. Investigation of robust flexible conformal THz perfect metamaterial absorber

    NASA Astrophysics Data System (ADS)

    Kim, Ju-Hyung; Hokmabadi, Mohammad P.; Balci, Soner; Rivera, Elmer; Wilbert, David; Kung, Patrick; Kim, Seongsin Margaret

    2016-04-01

    The flexible metamaterials have promised to greatly expand our ability to realize a wide range of novel applications including new methods of sensing and cloaking. In this work, flexible metamaterial absorbers, targeted to operate at terahertz frequencies, have been designed, simulated, and fabricated. The absorber structure consisted of a conducting ground plane, a dielectric spacer, and a frequency selective surface which was composed of two layers of nonconcentric, differently sized, single-ring arrays. Absorber structure was designed and simulated such that absorbers exhibited two distinct resonance frequencies with the strength of absorption for both sensitive to the center-to-center spacing of the rings and polarization. The functionality of the absorbers was seen to be similar both in planar and deformed positions, which promises robustness of the conformal flexible metamaterials device under the deformation and uneven surfaces.

  20. Thermally induced nonlinear optical absorption in metamaterial perfect absorbers

    NASA Astrophysics Data System (ADS)

    Guddala, Sriram; Kumar, Raghwendra; Ramakrishna, S. Anantha

    2015-03-01

    A metamaterial perfect absorber consisting of a tri-layer (Al/ZnS/Al) metal-dielectric-metal system with top aluminium nano-disks was fabricated by laser-interference lithography and lift-off processing. The metamaterial absorber had peak resonant absorbance at 1090 nm and showed nonlinear absorption for 600ps laser pulses at 1064 nm wavelength. A nonlinear saturation of reflectance was measured to be dependent on the average laser power incident and not the peak laser intensity. The nonlinear behaviour is shown to arise from the heating due to the absorbed radiation and photo-thermal changes in the dielectric properties of aluminium. The metamaterial absorber is seen to be damage resistant at large laser intensities of 25 MW/cm2.

  1. Thermally induced nonlinear optical absorption in metamaterial perfect absorbers

    SciTech Connect

    Guddala, Sriram Kumar, Raghwendra; Ramakrishna, S. Anantha

    2015-03-16

    A metamaterial perfect absorber consisting of a tri-layer (Al/ZnS/Al) metal-dielectric-metal system with top aluminium nano-disks was fabricated by laser-interference lithography and lift-off processing. The metamaterial absorber had peak resonant absorbance at 1090 nm and showed nonlinear absorption for 600ps laser pulses at 1064 nm wavelength. A nonlinear saturation of reflectance was measured to be dependent on the average laser power incident and not the peak laser intensity. The nonlinear behaviour is shown to arise from the heating due to the absorbed radiation and photo-thermal changes in the dielectric properties of aluminium. The metamaterial absorber is seen to be damage resistant at large laser intensities of 25 MW/cm{sup 2}.

  2. Theory of patch-antenna metamaterial perfect absorbers

    NASA Astrophysics Data System (ADS)

    Bowen, Patrick T.; Baron, Alexandre; Smith, David R.

    2016-06-01

    A metasurface that absorbs waves from all directions of incidence can be achieved if the surface impedance is made to vary as a function of incidence angle in a specific manner. Here we show that a periodic array of planar nanoparticles coupled to a metal film can act as an absorbing metasurface with an angle-dependent impedance. Through a semi-analytical calculation based on coupled-mode theory, we find the perfect absorbing condition is equivalent to balancing the Ohmic and radiative losses of the nanoparticles at normal incidence. Absorption over a wide range of incidence angles can then be obtained by tailoring the scattered far-field pattern of the individual planar nanoparticles such that their radiative losses remain constant. The theory provides a means of understanding the behavior of perfect absorbing structures that have been observed experimentally or numerically, reconciling previously published theories and enabling the optimization of absorbing surfaces.

  3. Performance evaluation of CFRP-rubber shock absorbers

    SciTech Connect

    Lamanna, Giuseppe Sepe, Raffaele

    2014-05-15

    In the present work a numerical investigation on the energy absorbing capability of dedicated structural components made of a carbon fiber reinforced polymer and an emulsion polymerised styrene butadiene rubber is reported. The shock absorbers are devices designed to absorb large amounts of energy by sacrificing their own structural integrity. Their aim is to cushion the effects of an impact phenomenon with the intent to preserve other structures from global failure or local damaging. Another important role of shock absorbers is reducing the peak of the acceleration showed during an impact phenomenon. This effect is of considerable interest in the case of vehicles to preserve passengers’ safety. Static and dynamic numerical results are compared with experimental ones in terms of mean crushing forces, energy and peak crushing. The global performance of the absorbers has been evaluated by referencing to a proposed quality index.

  4. Broadband terahertz metamaterial absorber based on sectional asymmetric structures.

    PubMed

    Gong, Cheng; Zhan, Mingzhou; Yang, Jing; Wang, Zhigang; Liu, Haitao; Zhao, Yuejin; Liu, Weiwei

    2016-01-01

    We suggest and demonstrate the concept and design of sectional asymmetric structures which can manipulate the metamaterial absorber's working bandwidth with maintaining the other inherent advantages. As an example, a broadband terahertz perfect absorber is designed to confirm its effectiveness. The absorber's each cell integrates four sectional asymmetric rings, and the entire structure composed of Au and Si3N4 is only 1.9 μm thick. The simulation results show the bandwidth with absorptivity being larger than 90% is extended by about 2.8 times comparing with the conventional square ring absorber. The composable small cell, ultra-thin, and broadband absorption with polarization and incident angle insensitivity will make the absorber suitable for the applications of focal plane array terahertz imaging. PMID:27571941

  5. Tracking the Partial Covering Absorbers in NGC 2110 with Suzaku: Constraints on Clumpy Absorber Models

    NASA Astrophysics Data System (ADS)

    Rothschild, Richard

    How do matter, energy, space and time behave under the extraordinarily diverse conditions of the cosmos? How did the Universe originate and evolve to produce the galaxies we see today? These are some of the biggest unanswered questions in astronomy today. In our study of Active Galactic Nuclei (AGN) we want to explore these questions and ask more explicitly what is the accretion history of the Universe? How do supermassive black holes acquire material and what happens when it does? To answer this we need to know the physical conditions and geometry of the accreting circumnuclear material in the vicinity of the supermassive black holes in AGN. This is an important piece of the AGN puzzle that we are able to study through detailed X-ray spectroscopic observations of AGN. We herein request support for our analysis of two Suzaku observations of the AGN NGC 2110, an unpublished archival observation from 2005 and an upcoming observation. This type 2 Seyfert AGN shows significant obscuration in the soft X-ray band from a complex of multiple absorbers with different column densities and covering fractions. Studying these partial-covering absorbers can tell us about the material surrounding the central black hole. We can learn how much material there is by through the level of absorption and the location of the accreting gas from the black hole via measurements of the level of ionization. Additionally, covering fractions and particularly time variability of covering fractions can hint at the clumpiness of the medium. Taking advantage of Suzaku s large energy range we can also quantify the Compton reflection hump, a broad spectral feature which peaks around 20 30 keV and is indicative of reflection off Compton-thick material in the vicinity of the central black hole. most likely either the accretion disk itself or a geometrically thick torus of material further out. The nature of this material is still an open question and recent work has been done using infrared

  6. ABSORBING WIPP BRINES: A TRU WASTE DISPOSAL STRATEGY

    SciTech Connect

    Yeamans, D. R.; Wrights, R. S.

    2002-02-25

    Los Alamos National Laboratory (LANL) has completed experiments involving 15 each, 250- liter experimental test containers of transuranic (TRU) heterogeneous waste immersed in two types of brine similar to those found in the underground portion of the Waste Isolation Pilot Plant (WIPP). To dispose of the waste without removing the brine from the test containers, LANL added commercially available cross-linked polyacrylate granules to absorb the 190 liters of brine in each container, making the waste compliant for shipping to the WIPP in a Standard Waste Box (SWB). Prior to performing the absorption, LANL and the manufacturer of the absorbent conducted laboratory and field tests to determine the ratio of absorbent to brine that would fully absorb the liquid. Bench scale tests indicated a ratio of 10 parts Castile brine to one part absorbent and 6.25 parts Brine A to one part absorbent. The minimum ratio of absorbent to brine was sought because headspace in the containers was limited. However, full scale testing revealed that the ratio should be adjusted to be about 15% richer in absorbent. Additional testing showed that the absorbent would not apply more than 13.8 kPa pressure on the walls of the vessel and that the absorbent would still function normally at that pressure and would not degrade in the approximately 5e-4 Sv/hr radioactive field produced by the waste. Heat generation from the absorption was minimal. The in situ absorption created a single waste stream of 8 SWBs whereas the least complicated alternate method of disposal would have yielded at least an additional 2600 liters of mixed low level liquid waste plus about two cubic meters of mixed low level solid waste, and would have resulted in higher risk of radiation exposure to workers. The in situ absorption saved $311k in a combination of waste treatment, disposal, material and personnel costs compared to the least expensive alternative and $984k compared to the original plan.

  7. Absorbing WIPP brines : a TRU waste disposal strategy.

    SciTech Connect

    Yeamans, D. R.; Wright, R.

    2002-01-01

    Los Alamos National Laboratory (LANL) has completed experiments involving 15 each, 250-liter experimental test containers of transuranic (TRU) heterogeneous waste immersed in two types of brine similar to those found in the underground portion of the Waste Isolation Pilot Plant (WIPP). To dispose of the waste without removing the brine from the test containers, LANL added commercially available cross-linked polyacrylate granules to absorb the 190 liters of brine in each container, making the waste compliant for shipping to the WlPP in a Standard Waste Box (SWB). Prior to performing the absorption, LANL and the manufacturer of the absorbent conducted laboratory and field tests to determine the ratio of absorbent to brine that would fully absorb the liquid. Bench scale tests indicated a ratio of 10 parts Castile brine to one part absorbent and 6.25 parts Brine A to one part absorbent. The minimum ratio of absorbent to brine was sought because headspace in the containers was limited. However, full scale testing revealed that the ratio should be adjusted to be about 15% richer in absorbent. Additional testing showed that the absorbent would not apply more than 13.8 kPa pressure on the walls of the vessel and that the absorbent would still function normally at that pressure and would not degrade in the approximately 5e-4 Sv/hr radioactive field produced by the waste. Heat generation from the absorption was minimal. The in situ absorption created a single waste stream of 8 SWBs whereas the least complicated alternate method of disposal would have yielded at least an additional 2600 liters of mixed low level liquid waste plus about two cubic meters of mixed low level solid waste, and would have resulted in higher risk of radiation exposure to workers. The in situ absorption saved $3 1 lk in a combination of waste treatment, disposal, material and personnel costs compared to the least expensive alternative and $984k compared to the original plan.

  8. High-precision temperature determination of evaporating light-absorbing and non-light-absorbing droplets.

    PubMed

    Derkachov, G; Jakubczyk, D; Woźniak, M; Archer, J; Kolwas, M

    2014-10-30

    Models describing evaporation or condensation of a droplet have existed for over a century, and the temporal evolutions of droplet radius and temperature could be predicted. However, the accuracy of results was questionable, since the models contain free parameters and the means of accurate calibration were not available. In previous work (Hołyst et al. Soft Matter 2013, 9, 7766), a model with an efficacious parametrization in terms of the mean free path was proposed and calibrated with molecular dynamics numerical experiment. It was shown that it is essentially possible to determine reliably the temperature of a steadily evaporating/condensing homogeneous droplet relative to ambient temperature when the evolution of the droplet radius is known. The accuracy of such measurement can reach fractions of mK. In the case of an evaporating droplet of pure liquid, the (droplet) temperature is constant during the stationary stage of evaporation. In this paper, we show that, in many cases, it is also possible to determine the temporal evolution of droplet temperature from the evolution of the droplet radius if the droplet (initial) composition is known. We found the droplet radius evolution with high accuracy and obtained the evolution of droplet temperature (and composition) for droplets of (i) a two-component mixture of pure liquids; (ii) solutions of solid in liquid, one that is non-surface-active and another that is; and (iii) suspensions of non-light-absorbing and light-absorbing particles. PMID:25290035

  9. Microwave absorbance properties of zirconium–manganese substituted cobalt nanoferrite as electromagnetic (EM) wave absorbers

    SciTech Connect

    Khan, Kishwar Rehman, Sarish

    2014-02-01

    Highlights: • Good candidates for EM materials with low reflectivity. • Good candidates for broad bandwidth at microwave frequency. • Microwave absorbing bandwidth was modulated simply by manipulating the Zr–Mn. • Higher the Zr–Mn content, the higher absorption rates for the electromagnetic radiation. • The predicted reflection loss shows that this can be used for thin ferrite absorber. - Abstract: Nanocrystalline Zr–Mn (x) substituted Co ferrite having chemical formula CoFe{sub 2−2x}Zr{sub x}Mn{sub x}O{sub 4} (x = 0.1–0.4) was prepared by co-precipitation technique. Combining properties such as structural, electrical, magnetic and reflection loss characteristics. Crystal structure and surface morphology of the calcined samples were characterized by X-ray diffraction analysis (XRD) and scanning electron microscopy (SEM). By using two point probe homemade resistivity apparatus to find resistivity of the sample. Electromagnetic (EM) properties are measured through RF impedance/materials analyzer over 1 MHz–3 GHz. The room-temperature dielectric measurements show dispersion behavior with increasing frequency from 100 Hz to 3 MHz. Magnetic properties confirmed relatively strong dependence of saturation magnetization on Zr–Mn composition. Curie temperature is also found to decrease linearly with addition of Zr–Mn. Furthermore, comprehensive analysis of microwave reflection loss (RL) is carried out as a function of substitution, frequency, and thickness. Composition accompanying maximum microwave absorption is suggested.

  10. Practical multi-featured perfect absorber utilizing high conductivity silicon

    NASA Astrophysics Data System (ADS)

    Gok, Abdullah; Yilmaz, Mehmet; Bıyıklı, Necmi; Topallı, Kağan; Okyay, Ali K.

    2016-03-01

    We designed all-silicon, multi-featured band-selective perfect absorbing surfaces based on CMOS compatible processes. The center wavelength of the band-selective absorber can be varied between 2 and 22 μm while a bandwidth as high as 2.5 μm is demonstrated. We used a silicon-on-insulator (SOI) wafer which consists of n-type silicon (Si) device layer, silicon dioxide (SiO2) as buried oxide layer, and n-type Si handle layer. The center wavelength and bandwidth can be tuned by adjusting the conductivity of the Si device and handle layers as well as the thicknesses of the device and buried oxide layers. We demonstrate proof-of-concept absorber surfaces experimentally. Such absorber surfaces are easy to microfabricate because the absorbers do not require elaborate microfabrication steps such as patterning. Due to the structural simplicity, low-cost fabrication, wide spectrum range of operation, and band properties of the perfect absorber, the proposed multi-featured perfect absorber surfaces are promising for many applications. These include sensing devices, surface enhanced infrared absorption applications, solar cells, meta-materials, frequency selective sensors and modulators.

  11. Absorbing-state phase transitions with extremal dynamics

    NASA Astrophysics Data System (ADS)

    Dickman, Ronald; Garcia, Guilherme J. M.

    2005-06-01

    Extremal dynamics represents a path to self-organized criticality in which the order parameter is tuned to a value of zero. The order parameter is associated with a phase transition to an absorbing state. Given a process that exhibits a phase transition to an absorbing state, we define an “extremal absorbing” process, providing the link to the associated extremal (nonabsorbing) process. Stationary properties of the latter correspond to those at the absorbing-state phase transition in the former. Studying the absorbing version of an extremal dynamics model allows to determine certain critical exponents that are not otherwise accessible. In the case of the Bak-Sneppen (BS) model, the absorbing version is closely related to the “ f -avalanche” introduced by Paczuski, Maslov, and Bak [Phys. Rev. E 53, 414 (1996)], or, in spreading simulations to the “BS branching process” also studied by these authors. The corresponding nonextremal process belongs to the directed percolation universality class. We revisit the absorbing BS model, obtaining refined estimates for the threshold and critical exponents in one dimension. We also study an extremal version of the usual contact process, using mean-field theory and simulation. The extremal condition slows the spread of activity and modifies the critical behavior radically, defining an “extremal directed percolation” universality class of absorbing-state phase transitions. Asymmetric updating is a relevant perturbation for this class, even though it is irrelevant for the corresponding nonextremal class.

  12. Innovative Anti Crash Absorber for a Crashworthy Landing Gear

    NASA Astrophysics Data System (ADS)

    Guida, Michele; Marulo, Francesco; Montesarchio, Bruno; Bruno, Massimiliano

    2014-06-01

    This paper defines an innovative concept to anti-crash absorber in composite material to be integrated on the landing gear as an energy-absorbing device in crash conditions to absorb the impact energy. A composite cylinder tube in carbon fiber material is installed coaxially to the shock absorber cylinder and, in an emergency landing gear condition, collapses in order to enhance the energy absorption performance of the landing system. This mechanism has been developed as an alternative solution to a high-pressure chamber installed on the Agusta A129 CBT helicopter, which can be considered dangerous when the helicopter operates in hard and/or crash landing. The characteristics of the anti-crash device are presented and the structural layout of a crashworthy landing gear adopting the developed additional energy absorbing stage is outlined. Experimental and numerical results relevant to the material characterization and the force peaks evaluation of the system development are reported. The anti-crash prototype was designed, analysed, optimized, made and finally the potential performances of a landing gear with the additional anti-crash absorber system are tested by drop test and then correlated with a similar test without the anti-crash system, showing that appreciable energy absorbing capabilities and efficiencies can be obtained in crash conditions.

  13. Broadband ultrathin low-profile metamaterial microwave absorber

    NASA Astrophysics Data System (ADS)

    Sood, Deepak; Tripathi, Chandra Charu

    2016-04-01

    In this paper, a single-layer broadband low-profile ultrathin metamaterial microwave absorber is proposed for wide angle of incidence. The proposed absorber provides triple-band absorption under normal incidence of electromagnetic wave with two peaks lying in X-band and one in Ku-band. The unit cell is designed by using parametric optimization in such a way that the three peaks merge together to give broadband absorption. The absorber exhibits full width at half maxima bandwidth (FWHM) of 7.75 GHz from 7.55 to 15.30 GHz for wide angle of incidence up to 60° for both TE and TM polarizations. The mechanism of absorption of the absorber has been analyzed by field and surface current distributions. The proposed absorber has been fabricated and experimentally tested for different angles of incidence and polarization of the incident wave. The absorber is low profile with unit cell dimension of the order of 0.168 λ 0, and it is ultrathin with a thickness of ~ λ 0/17 at the center frequency of 11.43 GHz corresponding to the FWHM absorption bandwidth. This proposed absorber can be used for many potential applications such as stealth technology, cloaking and in antenna systems.

  14. Interaction of inhalational anaesthetics with CO2 absorbents.

    PubMed

    Baum, Jan A; Woehlck, Harvey J

    2003-03-01

    We review the currently available carbon dioxide absorbents: sodium hydroxide lime (=soda lime), barium hydroxide lime, potassium-hydroxide-free soda lime, calcium hydroxide lime and non-caustic lime. In general, all of these carbon dioxide absorbents are liable to react with inhalational anaesthetics. However, there is a decreasing reactivity of the different absorbents with inhalational anaesthetics: barium hydroxide lime > soda lime > potassium-hydroxide-free soda lime > calcium hydroxide lime and non-caustic lime. Gaseous compounds generated by the reaction of the anaesthetics with desiccated absorbents are those that threaten patients. All measures are comprehensively described to--as far as possible--prevent any accidental drying out of the absorbent. Whether or not compound A, a gaseous compound formed by the reaction of sevoflurane with normally hydrated absorbents, is still a matter of concern is discussed. Even after very high loading with this compound, during long-lasting low-flow sevoflurane anaesthesias, no clinical or laboratory signs of renal impairment were observed in any of the surgical patients. Finally, guidelines for the judicious use of different absorbents are given. PMID:12751549

  15. Simulation, Fabrication and Characterization of THz Metamaterial Absorbers

    PubMed Central

    Grant, James P.; McCrindle, Iain J.H.; Cumming, David R.S.

    2012-01-01

    Metamaterials (MM), artificial materials engineered to have properties that may not be found in nature, have been widely explored since the first theoretical1 and experimental demonstration2 of their unique properties. MMs can provide a highly controllable electromagnetic response, and to date have been demonstrated in every technologically relevant spectral range including the optical3, near IR4, mid IR5 , THz6 , mm-wave7 , microwave8 and radio9 bands. Applications include perfect lenses10, sensors11, telecommunications12, invisibility cloaks13 and filters14,15. We have recently developed single band16, dual band17 and broadband18 THz metamaterial absorber devices capable of greater than 80% absorption at the resonance peak. The concept of a MM absorber is especially important at THz frequencies where it is difficult to find strong frequency selective THz absorbers19. In our MM absorber the THz radiation is absorbed in a thickness of ~ λ/20, overcoming the thickness limitation of traditional quarter wavelength absorbers. MM absorbers naturally lend themselves to THz detection applications, such as thermal sensors, and if integrated with suitable THz sources (e.g. QCLs), could lead to compact, highly sensitive, low cost, real time THz imaging systems. PMID:23299442

  16. Specific heat investigation for line nodes in heavily overdoped Ba1-xKxFe2As2

    DOE PAGESBeta

    Kim, J. S.; Stewart, G. R.; Liu, Yong; Lograsso, Thomas A.

    2015-06-10

    Previous research has found that the pairing symmetry in the iron-based superconductor Ba1-xKxFe2As2 changes from nodeless s-wave near optimally doped, x≈0.4-0.55 and Tc>30 K, to nodal (either d-wave or s-wave) at the pure endpoint, x=1 and Tc<4 K. Intense theoretical interest has been focused on this possibility of changing pairing symmetry, where in the transition region both order parameters would be present and time reversal symmetry would be broken. Here we report specific heat measurements in zero and applied magnetic fields down to 0.4 K of three individual single crystals, free of low temperature magnetic anomalies, of heavily overdoped Ba1-xKxFe2As2,more » x= 0.91, 0.88, and 0.81. The values for Tcmid are 5.6, 7.2 and 13 K and for Hc2≈ 4.5, 6, and 20 T respectively. Furthermore, the data can be analyzed in a two gap scenario, Δ2/Δ1 ≈ 4, with the magnetic field dependence of γ (=C/T as T→0) showing an anisotropic ‘S-shaped’ behavior vs H, with the suppression of the lower gap by 1 T and γ ≈ H1/2 overall. Although such a non-linear γ vs H is consistent with deep minima or nodes in the gap structure, it is not clear evidence for one, or both, of the gaps being nodal in these overdoped samples. Thus, following the established theoretical analysis of the specific heat of d-wave cuprate superconductors containing line nodes, we present the specific heat normalized by H1/2 plotted vs T/H1/2 of these heavily overdoped Ba1-xKxFe2As2 samples which – thanks to the absence of magnetic impurities in our sample - convincingly shows the expected scaling for line node behavior for the larger gap for all three compositions. There is however no clear observation of the nodal behavior C ∝ αT2 in zero field at low temperatures, with α ≤ 2 mJ/molK3 being consistent with the data. Together with the scaling, this leaves open the possibility of extreme anisotropy in a nodeless larger gap, Δ2, such that the scaling works for fields above 0.25 – 0

  17. Comparison of piezoelectronic networks acting as distributed vibration absorbers

    NASA Astrophysics Data System (ADS)

    Maurini, Corrado; dell'Isola, Francesco; Del Vescovo, Dionisio

    2004-09-01

    Electric vibration absorbers made of distributed piezoelectric devices for the control of beam vibrations are studied. The absorbers are obtained by interconnecting an array of piezoelectric transducers uniformly distributed on a beam with different modular electric networks. Five different topologies are considered and their damping performance is analysed and compared. Their optimal parameters are found by adopting a criterion for critical damping of k¯-waves: the parameters are suitably chosen to have the quickest temporal vibration decay for a single wave number k¯. The analysis is based on homogenized models of the modular piezo-electromechanical systems, i.e. they are regarded as continuous systems by assuming that the number of modules per unit length is high enough with respect to the considered wave numbers. Calling k¯ -absorbers the corresponding optimal absorbers, we show that: (i) k¯-waves are damped in k¯-absorbers with an optimal decay time which is independent of the absorber interconnecting topology, while it depends only on the piezoelectric coupling coefficient; (ii) the efficiency of k¯-absorbers depends significantly on the absorber interconnecting topology for k different from k¯; (iii) one of the proposed absorbers (which is made of a fourth-order electric transmission line with a second-order electric dissipation) equally performs for all the wave numbers and accomplishes an effective multi-modal damping for the mechanically forced response; (iv) the optimal values of the electric parameters differently depend on the number n of used circuit modules for different interconnecting topologies and, in particular, the optimal inductance per module needed in a fourth-order electric transmission line is proportional 1/ n3.

  18. [Efficiency of Sediment Amendment with Zirconium-Modified Kaolin Clay to Control Phosphorus Release from Sediments in Heavily Polluted Rivers].

    PubMed

    Wang, Hong; Lin, Jian-wei; Zhan, Yan-hui; Zhang, Zhe; Wang, Di-ru

    2015-10-01

    A zirconium-modified kaolin- clay (ZrMK) was prepared and used as a sediment amendment to control the release of phosphorus (P) from sediments in heavily polluted rivers under low dissolved oxygen (DO) condition. Results showed that the ZrMK exhibited excellent adsorption performance of phosphate in water. The phosphate adsorption capacity of the ZrMK increased with the increasing of loading amount of zirconium in the ZrMK. The phosphate adsorption capacity of the ZrMK increased with the increase of the precipitated pH value from 8 to 10, remained basically unchangeable with the increase of the precipitated pH value from 10 to 11, but decreased with the increase of the precipitated pH value from 11 to 12. The phosphate equilibrium adsorption data of the ZrMK can be better described by the Langmuir isotherm model than the Freundlich isotherm model when the ZrMK was prepared with the precipitated pH value 10. Sequential extraction of P from the phosphate-adsorbed ZrMK showed that most of phosphate-P bound by the ZrMK (about 84% of total P) existed in the form of the metal oxide P (NaOH-P) and residual P (Res-P), which was unlikely to be released under hypoxia and common pH (5-9) conditions. The fluxes of phosphate-P and total P (TP) from sediments into the overlying water column were greatly reduced with the adding of ZrMK to sediments under low dissolved oxygen conditions. The ZrMK-amended sediments exhibited much higher phosphate adsorption capacity than the original sediments, and the former had much lower phosphate adsorption/desorption equilibrium concentration (EPC,) than the latter. Our findings suggest that the ZrMK can be used as an efficient sediment amendment for controlling P release from sediments in heavily polluted rivers under low dissolved oxygen conditions. PMID:26841604

  19. Optimization of the acoustic absorption coefficients of certain functional absorbents

    NASA Technical Reports Server (NTRS)

    Pocsa, V.; Biborosch, L.; Veres, A.; Halpert, E.; Lorian, R.; Botos, T.

    1974-01-01

    The sound absorption coefficients of some functional absorbents (mineral wool plates) are determined by the reverberation chamber method. The influence of the angle of inclination of the sound absorbing material with respect to the surface to be treated is analyzed as well as the influence of the covering index, defined as the ratio of the designed area of a plate and the area of the treated surface belonging to another plate. As compared with the conventional method of applying sound-absorbing plates, the analyzed structures have a higher technological and economical efficiency. The optimum structure corresponds to an angle of inclination of 15 deg and a covering index of 0.8.

  20. Automated Absorber Attachment for X-ray Microcalorimeter Arrays

    NASA Technical Reports Server (NTRS)

    Moseley, S.; Allen, Christine; Kilbourne, Caroline; Miller, Timothy M.; Costen, Nick; Schulte, Eric; Moseley, Samuel J.

    2007-01-01

    Our goal is to develop a method for the automated attachment of large numbers of absorber tiles to large format detector arrays. This development includes the fabrication of high quality, closely spaced HgTe absorber tiles that are properly positioned for pick-and-place by our FC150 flip chip bonder. The FC150 also transfers the appropriate minute amount of epoxy to the detectors for permanent attachment of the absorbers. The success of this development will replace an arduous, risky and highly manual task with a reliable, high-precision automated process.

  1. HS 1603+3820 and its Warm Absorber

    NASA Astrophysics Data System (ADS)

    Nikołajuk, M.; Różańska, A.; Czerny, B.; Dobrzycki, A.

    2009-07-01

    We use photoionization codes CLOUDY and TITAN to obtain physical conditions in the absorbing medium close to the nucleus of a distant quasar (z = 2.54) HS 1603+3820. We found that the total column density of this Warm Absorber is 2 x 1022 cm-2. Due to the softness of the quasars spectrum the modelling allowed us also to determine uniquely the volume hydrogen density of this warm gas (n = 1010 cm-3) which combined with the other quasar parameters leads to a distance determination to the Warm Absorber from the central source which is ~ 1.5 x 1016 cm.

  2. Metamaterial perfect absorber based on artificial dielectric "atoms".

    PubMed

    Liu, Xiaoming; Bi, Ke; Li, Bo; Zhao, Qian; Zhou, Ji

    2016-09-01

    In this work, we numerically designed and then experimentally verified a metamaterial perfect absorber based on artificial dielectric "atoms". This metamaterial absorber is composed of dielectric ceramic material (SrTiO3) "atoms" embedded in a background matrix on a metal plate. The dielectric "atoms" couple strongly to the incident electric and magnetic fields at the Mie resonance mode, leading to the narrow perfect absorption band with simulated and experimental absorptivities of 99% and 98.5% at 8.96 GHz, respectively. The designed metamaterial perfect absorber is polarization insensitive and can operate in wide angle incidence. PMID:27607650

  3. Wedge absorber design and simulation for MICE Step IV

    SciTech Connect

    Rogers, C.T.; Snopok, P.; Coney, L.; Hanson, G.; /UC, Riverside

    2011-03-01

    In the Muon Ionization Cooling Experiment (MICE), muons are cooled by passing through material, then through RF cavities to compensate for the energy loss; which reduces the transverse emittance. It is planned to demonstrate longitudinal emittance reduction via emittance exchange in MICE by using a solid wedge absorber in Step IV. Based on the outcome of previous studies, the shape and material of the wedge were chosen. We address here further simulation efforts for the absorber of choice as well as engineering considerations in connection with the absorber support design.

  4. Solar absorber material stability under high solar flux

    NASA Astrophysics Data System (ADS)

    Ignatiev, A.; Zajac, G.; Smith, G. B.

    1982-04-01

    Solar absorbing Black Chrome coatings have been exposed to high temperatures (350-400 C) under high solar fluxes (0.4 to 2.0 MW/sq m) to test for their stability under actual operating conditions. Field tests at the White Sands Solar Furnace have shown higher stability than expected from oven tested samples. Laboratory studies utilizing spectrally selective concentrated solar simulated radiation have indicated that the cause of the higher stability under solar irradiation is photo-stimulated desorption of oxygen bearing species at the absorber surface and resultant reduced oxidation of the absorber.

  5. Flexible subterahertz metamaterial absorber fabrication using inkjet printing technology

    NASA Astrophysics Data System (ADS)

    Lee, Dongju; Sung, Hyuk-Kee; Lim, Sungjoon

    2016-07-01

    In this study, a flexible metamaterial (MM) absorber was designed at 0.1 THz and fabricated using inkjet printing technology. The unit cell of the MM absorber was designed using a finite element method-based full-wave simulation. The unit cell comprised square rings, and it was printed with silver nanoparticle ink on flexible Kapton polyimide film. The fabrication processes were performed using a material printer. The absorber's reflection coefficient was measured using a vector network analyzer and a WR-10 waveguide. The absorption ratio was 93.5 % at 0.102 THz. Therefore, we demonstrated the possibility of inkjet printing at a subterahertz band.

  6. Fundamental research on oscillating water column wave power absorbers

    SciTech Connect

    Maeda, H.; Kato, W.; Kinoshita, T.; Masuda, K.

    1985-03-01

    An oscillating water column (OWC) wave power absorber is one of the most promising devices, as well as the Salter Duck and the Clam. This paper presents a simple prediction method, in which the equivalent floating body approximation is used, for absorbing wave power characteristics of an oscillating water column device. The effects of the compressibility of air and inertia of an air turbine and electric generator on absorbed wave power are obtained by using the equivalent electric circuit concept. Both the experimental and theoretical studies are carried out in this paper.

  7. Theoretical investigation of the formation of basal plane stacking faults in heavily nitrogen-doped 4H-SiC crystals

    NASA Astrophysics Data System (ADS)

    Taniguchi, Chisato; Ichimura, Aiko; Ohtani, Noboru; Katsuno, Masakazu; Fujimoto, Tatsuo; Sato, Shinya; Tsuge, Hiroshi; Yano, Takayuki

    2016-04-01

    The formation of basal plane stacking faults in heavily nitrogen-doped 4H-SiC crystals was theoretically investigated. A novel theoretical model based on the so-called quantum well action mechanism was proposed; the model considers several factors, which were overlooked in a previously proposed model, and provides a detailed explanation of the annealing-induced formation of double layer Shockley-type stacking faults in heavily nitrogen-doped 4H-SiC crystals. We further revised the model to consider the carrier distribution in the depletion regions adjacent to the stacking fault and successfully explained the shrinkage of stacking faults during annealing at even higher temperatures. The model also succeeded in accounting for the aluminum co-doping effect in heavily nitrogen-doped 4H-SiC crystals, in that the stacking fault formation is suppressed when aluminum acceptors are co-doped in the crystals.

  8. Numerical simulations of heavily polluted fine-grained sediment remobilization using 1D, 1D+, and 2D channel schematization.

    PubMed

    Kaiglová, Jana; Langhammer, Jakub; Jiřinec, Petr; Janský, Bohumír; Chalupová, Dagmar

    2015-03-01

    This article used various hydrodynamic and sediment transport models to analyze the potential and the limits of different channel schematizations. The main aim was to select and evaluate the most suitable simulation method for fine-grained sediment remobilization assessment. Three types of channel schematization were selected to study the flow potential for remobilizing fine-grained sediment in artificially modified channels. Schematization with a 1D cross-sectional horizontal plan, a 1D+ approach, splitting the riverbed into different functional zones, and full 2D mesh, adopted in MIKE by the DHI modeling suite, was applied to the study. For the case study, a 55-km stretch of the Bílina River, in the Czech Republic, Central Europe, which has been heavily polluted by the chemical and coal mining industry since the mid-twentieth century, was selected. Long-term exposure to direct emissions of toxic pollutants including heavy metals and persistent organic pollutants (POPs) resulted in deposits of pollutants in fine-grained sediments in the riverbed. Simulations, based on three hydrodynamic model schematizations, proved that for events not exceeding the extent of the riverbed profile, the 1D schematization can provide comparable results to a 2D model. The 1D+ schematization can improve accuracy while keeping the benefits of high-speed simulation and low requirements of input DEM data, but the method's suitability is limited by the channel properties. PMID:25687259

  9. Coplanar amorphous-indium-gallium-zinc-oxide thin film transistor with He plasma treated heavily doped layer

    SciTech Connect

    Jeong, Ho-young; Lee, Bok-young; Lee, Young-jang; Lee, Jung-il; Yang, Myoung-su; Kang, In-byeong; Mativenga, Mallory; Jang, Jin

    2014-01-13

    We report thermally stable coplanar amorphous-indium-gallium-zinc-oxide (a-IGZO) thin-film transistors (TFTs) with heavily doped n{sup +} a-IGZO source/drain regions. Doping is through He plasma treatment in which the resistivity of the a-IGZO decreases from 2.98 Ω cm to 2.79 × 10{sup −3} Ω cm after treatment, and then it increases to 7.92 × 10{sup −2} Ω cm after annealing at 300 °C. From the analysis of X-ray photoelectron spectroscopy, the concentration of oxygen vacancies in He plasma treated n{sup +}a-IGZO does not change much after thermal annealing at 300 °C, indicating thermally stable n{sup +} a-IGZO, even for TFTs with channel length L = 4 μm. Field-effect mobility of the coplanar a-IGZO TFTs with He plasma treatment changes from 10.7 to 9.2 cm{sup 2}/V s after annealing at 300 °C, but the performance of the a-IGZO TFT with Ar or H{sub 2} plasma treatment degrades significantly after 300 °C annealing.

  10. Microbial Diversity of a Heavily Polluted Microbial Mat and Its Community Changes following Degradation of Petroleum Compounds

    PubMed Central

    Abed, Raeid M. M.; Safi, Nimer M. D.; Köster, Jürgen; de Beer, Dirk; El-Nahhal, Yasser; Rullkötter, Jürgen; Garcia-Pichel, Ferran

    2002-01-01

    We studied the microbial diversity of benthic cyanobacterial mats inhabiting a heavily polluted site in a coastal stream (Wadi Gaza) and monitored the microbial community response induced by exposure to and degradation of four model petroleum compounds in the laboratory. Phormidium- and Oscillatoria-like cyanobacterial morphotypes were dominant in the field. Bacteria belonging to different groups, mainly the Cytophaga-Flavobacterium-Bacteriodes group, the γ and β subclasses of the class Proteobacteria, and the green nonsulfur bacteria, were also detected. In slurry experiments, these communities efficiently degraded phenanthrene and dibenzothiophene completely in 7 days both in the light and in the dark. n-Octadecane and pristane were degraded to 25 and 34% of their original levels, respectively, within 7 days, but there was no further degradation until 40 days. Both cyanobacterial and bacterial communities exhibited noticeable changes concomitant with degradation of the compounds. The populations enriched by exposure to petroleum compounds included a cyanobacterium affiliated phylogenetically with Halomicronema. Bacteria enriched both in the light and in the dark, but not bacteria enriched in any of the controls, belonged to the newly described Holophaga-Geothrix-Acidobacterium phylum. In addition, another bacterial population, found to be a member of green nonsulfur bacteria, was detected only in the bacteria treated in the light. All or some of the populations may play a significant role in metabolizing the petroleum compounds. We concluded that the microbial mats from Wadi Gaza are rich in microorganisms with high biodegradative potential. PMID:11916684

  11. Heavily-doped ZnO:Al thin films prepared by using magnetron Co-sputtering: Optical and electrical properties

    NASA Astrophysics Data System (ADS)

    Moon, Eun-A.; Jun, Young-Kil; Kim, Nam-Hoon; Lee, Woo-Sun

    2016-07-01

    Photovoltaic applications require transparent conducting-oxide (TCO) thin films with high optical transmittance in the visible spectral region (380 - 780 nm), low resistivity, and high thermal/chemical stability. The ZnO thin film is one of the most common alternatives to the conventional indium-tin-oxide (ITO) thin film TCO. Highly transparent and conductive ZnO thin films can be prepared by doping with group III elements. Heavily-doped ZnO:Al (AZO) thin films were prepared by using the RF magnetron co-sputtering method with ZnO and Al targets to obtain better characteristics at a low cost. The RF sputtering power to each target was varied to control the doping concentration in fixed-thickness AZO thin films. The crystal structures of the AZO thin films were analyzed by using X-ray diffraction. The morphological microstructure was observed by using scanning electron microscopy. The optical transmittance and the band gap energy of the AZO thin films were examined with an UV-visible spectrophotometer in the range of 300 - 1800 nm. The resistivity and the carrier concentration were examined by using a Hall-effect measurement system. An excellent optical transmittance > 80% with an appropriate band gap energy (3.26 - 3.27 eV) and an improved resistivity (~10 -1 Ω·cm) with high carrier concentration (1017 - 1019 cm -3) were demonstrated in 350-nm-thick AZO thin films for thin-film photovoltaic applications.

  12. ARPES investigation of heavily hole-doped Fe-based superconductor (Ba,K)Fe2As2

    NASA Astrophysics Data System (ADS)

    Shi, Xun; Richard, Pierre; Zhang, Peng; van Roekeghem, Ambroise; Qian, Tian; Hu, Jiangping; Ding, Hong; Fang, Delong; Wen, Haihu; Xu, Nan; Shi, Ming; Kim, Timur; Hoesch, Moritz; Chen, Xianhui; Photoelectron Spectroscopy Research Team; Nanjing University Collaboration; Paul Scherrer Institut Collaboration; Diamond Light Source Collaboration; University of Science; Technology of China Collaboration

    A Lifshitz transition occurs in the (Ba,K)Fe2As2 family upon K doping and electron pocket are absent in the heavily doped compounds, including KFe2As2. The pairing symmetry is argued to undergoes a phase transition due to the existence of gap node(s) reported in various experiments. In this work we present angle-resolved photoemission spectroscopy and scanning tunneling spectroscopy studies of KFe2As2. We observe a van Hove singularity (vHs) in proximity of the Fermi level (EF), which locates in the middle of the principal axes of the first Brillouin zone. The density-of-states at EF mainly comes from the vHs whereas it is non-gapped in the superconducting state. Our observation provides natural explanations for many novel behaviors in this material. In particular, it is consistent with our measurements of the gap structure in Ba0.1K0.9Fe2As2. All these results suggest that Cooper pairing is induced by a strong-coupling mechanism.

  13. Isolation and characterization of a Siphoviridae phage infecting Bacillus megaterium from a heavily trafficked holy site in Saudi Arabia.

    PubMed

    Othman, B A; Askora, Ahmed; Abo-Senna, Amel S M

    2015-07-01

    In this study, we isolated and characterized a Siphoviridae phage isolated from the vicinity of a religious structure (Kaaba) in Makkah, Saudi Arabia. The phage was designated as φBM and characterized using transmission electron microscopy, restriction digestion of its DNA, and host range. Electron micrograph indicated that φBM phage has an icosahedral head with diameter of about 65 ± 5 nm and long, non-contractile tail with length of about 300 ± 10 nm and width of about 17 ± 2 nm, respectively. On the basis of the φBM phage morphology, we thus propose that φBM represents a member of Siphoviridae phages. The φBM phage was shown to be able to infect Bacillus megaterium and two other Bacillus species and has no effect on other tested bacteria. φBM was stable over the pH range of 5-9, chloroform resistant and stable at 4 °C. A one-step growth experiment showed a latent period of about 40 min and a burst size of approximately 65 per infected cell. The purified bacteriophage appeared to consist of ten proteins. The genome size was estimated to be ∼38 kb. To our knowledge, this is the first report on the isolation of a bacteriophage from Kaaba a heavily trafficked holy site in Saudi Arabia. PMID:25624065

  14. Effect of artificial aeration on the performance of vertical-flow constructed wetland treating heavily polluted river water.

    PubMed

    Dong, Huiyu; Qiang, Zhimin; Li, Tinggang; Jin, Hui; Chen, Weidong

    2012-01-01

    Three lab-scale vertical-flow constructed wetlands (VFCWs), including the non-aerated (NA), intermittently aerated (IA) and continuously aerated (CA) ones, were operated at different hydraulic loading rates (HLRs) to evaluate the effect of artificial aeration on the treatment efficiency of heavily polluted river water. Results indicated that artificial aeration increased the dissolved oxygen (DO) concentrations in IA and CA, which significantly favored the removal of organic matter and NH(4+)-N. The DO grads caused by intermittent aeration formed aerobic and anoxic regions in IA and thus promoted the removal of total nitrogen (TN). Although the removal efficiencies of COD(Cr), NH(4+)-N and TN in the three VFCWs all decreased with an increase in HLR, artificial aeration enhanced the reactor resistance to the fluctuation of pollutant loadings. The maximal removal efficiencies of COD(Cr), NH(4+)-N and total phosphorus (TP) (i.e., 81%, 87% and 37%, respectively) were observed in CA at 19 cm/day HLR, while the maximal TN removal (i.e., 57%) was achieved in IA. Although the improvement of artificial aeration on TP removal was limited, this study has demonstrated the feasibility of applying artificial aeration to VFCWs treating polluted river water, particularly at a high HLR. PMID:22894092

  15. Porous titania with heavily self-doped Ti3+ for specific sensing of CO at room temperature.

    PubMed

    Su, Juan; Zou, Xiao-Xin; Zou, Yong-Cun; Li, Guo-Dong; Wang, Pei-Pei; Chen, Jie-Sheng

    2013-05-20

    Semiconductor-based sensors have played an important role in efficient detection of combustible, flammable, and toxic gases, but they usually need to operate at elevated temperatures (200 °C or higher). Although reducing the operation temperature down to room temperature is of practical significance, it is still a huge challenge to fabricate room temperature sensors with a low cost. Here we show a novel "self-doping" strategy to overcome simultaneously both difficulties of "high resistance" and "low reaction rate", which have always been encountered for room-temperature operation of semiconductor-based sensors. In particular, a porous crystalline titania with heavily self-doped Ti(3+) species has been prepared by using a porous amorphous TiO2 and urea as the starting materials. The resulting Ti(3+) self-doped TiO2 material serves as an efficient room-temperature gas-sensing material for specific CO detection with fast response/recovery. The self-dopant (Ti(3+)) in the titania material has proved to decrease the resistance of TiO2 significantly on the one hand and to increase the chemisorbed oxygen species substantially, thus enhancing the surface reaction activity on the other. Such a self-doping concept is anticipated to give a fresh impetus to rational design of room-temperature sensing devices with low costs. PMID:23651218

  16. Miscellaneous additives can enhance plant uptake and affect geochemical fractions of copper in a heavily polluted riparian grassland soil.

    PubMed

    Rinklebe, Jörg; Shaheen, Sabry M

    2015-09-01

    The problem of copper (Cu) pollution in riverine ecosystems is world-wide and has significant environmental, eco-toxicological, and agricultural relevance. We assessed the suitability and effectiveness of application rate of 1% of activated charcoal, bentonite, biochar, cement kiln dust, chitosan, coal fly ash, limestone, nano-hydroxyapatite, organo-clay, sugar beet factory lime, and zeolite as soil amendments together with rapeseed as bioenergy crop as a possible remediation option for a heavily Cu polluted floodplain soil (total Cu=3041.9mgkg(-1)) that has a very high proportion of sorbed/carbonate fraction (484.6mgkg(-1)) and potential mobile fraction of Cu (1611.9mgkg(-1)). Application changed distribution of Cu among geochemical fractions: alkaline materials lead to increased carbonate bounded fraction and the acid rhizosphere zone might cause release of this Cu. Thus, mobilization of Cu and uptake of Cu by rapeseed were increased compared to the control (except for organo-clay) under the prevailing conditions. PMID:25968602

  17. Band Structure of the Heavily-Electron-Doped FeAs-Based Ba(Fe,​Co)2As2 Superconductor Suppresses Antiferromagnetic Correlations

    NASA Astrophysics Data System (ADS)

    Sudayama, T.; Wakisaka, Y.; Takubo, K.; Morinaga, R.; Sato, T. J.; Arita, M.; Namatame, H.; Taniguchi, M.; Mizokawa, T.

    2010-04-01

    In the heavily-electron-doped regime of the Ba(Fe,​Co)2As2 superconductor, three hole bands at the zone center are observed and two of them reach the Fermi level. The larger hole pocket at the zone center is apparently nested with the smaller electron pocket around the zone corner. However, the (π,​0) Fermi surface reconstruction reported for the hole-doped case is absent in the heavily-electron-doped case. This observation shows that the apparent Fermi surface nesting alone is not enough to enhance the antiferromagnetic correlation as well as the superconducting transition temperature.

  18. Carbon nanotube-based tandem absorber with tunable spectral selectivity: transition from near-perfect blackbody absorber to solar selective absorber.

    PubMed

    Selvakumar, N; Krupanidhi, S B; Barshilia, Harish C

    2014-04-23

    CVD grown CNT thin film with a thickness greater than 10 μm behaves like a near-perfect blackbody absorber (i.e., α/ε = 0.99/0.99). Whereas, for a thickness ≤ 0.4 µm, the CNT based tandem absorber acts as a spectrally selective coating (i.e., α/ε = 0.95/0.20). These selective coatings exhibit thermal stability up to 650 °C in vacuum, which can be used for solar thermal power generation. PMID:24474148

  19. Radio-absorbing properties of nickel-containing schungite powder

    NASA Astrophysics Data System (ADS)

    Lyn'kov, L. M.; Borbot'ko, T. V.; Krishtopova, E. A.

    2009-05-01

    A nickel-containing shungite powder has been synthesized by means of chemical reduction from aqueous solutions. The chemical composition and radio-absorbing properties of this powder have been studied.

  20. Stretchable Metamaterial Absorber Using Liquid Metal-Filled Polydimethylsiloxane (PDMS)

    PubMed Central

    Kim, Kyeongseob; Lee, Dongju; Eom, Seunghyun; Lim, Sungjoon

    2016-01-01

    A stretchable metamaterial absorber is proposed in this study. The stretchability was achieved by liquid metal and polydimethylsiloxane (PDMS). To inject liquid metal, microfluidic channels were fabricated using PDMS powers and microfluidic-channel frames, which were built using a three-dimensional printer. A top conductive pattern and ground plane were designed after considering the easy injection of liquid metal. The proposed metamaterial absorber comprises three layers of PDMS substrate. The top layer is for the top conductive pattern, and the bottom layer is for the meandered ground plane. Flat PDMS layers were inserted between the top and bottom PDMS layers. The measured absorptivity of the fabricated absorber was 97.8% at 18.5 GHz, and the absorption frequency increased from 18.5 to 18.65 GHz as the absorber was stretched from its original length (5.2 cm) to 6.4 cm. PMID:27077861

  1. Microwave-absorbing properties of Co-filled carbon nanotubes

    SciTech Connect

    Lin Haiyan; Zhu Hong Guo Hongfan; Yu Liufang

    2008-10-02

    Co-filled carbon nanotubes composites were synthesized via using a simple and efficient wet chemistry solution method. The samples were characterized by transmission electron microscopy. Microwave-absorbing properties were investigated by measuring complex permittivity and complex permeability of the absorber in a frequency range of 2-18 GHz. The reflection loss (R.L.), matching frequency (f{sub m}) and matching thickness (d{sub m}) were calculated using the theory of the absorbing wall. The electromagnetic properties and microwave-absorbing characteristics effects of the modified carbon nanotubes by the encapsulation of metal Co were investigated. A matching thickness is found corresponding to a matching frequency. The maximum reflection loss is about -39.32 dB and the bandwidth corresponding to the reflection loss below -10 dB is 3.47 GHz. With increasing thickness, the maximum reflection loss shifts to lower frequency.

  2. Absorbing boundary conditions for second-order hyperbolic equations

    NASA Technical Reports Server (NTRS)

    Jiang, Hong; Wong, Yau Shu

    1989-01-01

    A uniform approach to construct absorbing artificial boundary conditions for second-order linear hyperbolic equations is proposed. The nonlocal boundary condition is given by a pseudodifferential operator that annihilates travelling waves. It is obtained through the dispersion relation of the differential equation by requiring that the initial-boundary value problem admits the wave solutions travelling in one direction only. Local approximation of this global boundary condition yields an nth-order differential operator. It is shown that the best approximations must be in the canonical forms which can be factorized into first-order operators. These boundary conditions are perfectly absorbing for wave packets propagating at certain group velocities. A hierarchy of absorbing boundary conditions is derived for transonic small perturbation equations of unsteady flows. These examples illustrate that the absorbing boundary conditions are easy to derive, and the effectiveness is demonstrated by the numerical experiments.

  3. Diagnostic beam absorber in Mu2e beam line

    SciTech Connect

    Rakhno, Igor; /Fermilab

    2011-03-01

    Star density, hadron flux, and residual dose distributions are calculated around the {mu}2e diagnostic beam absorber. Corresponding surface and ground water activation, and air activation are presented as well.

  4. Absorbing boundary conditions for second-order hyperbolic equations

    NASA Technical Reports Server (NTRS)

    Jiang, Hong; Wong, Yau Shu

    1990-01-01

    A uniform approach to construct absorbing artificial boundary conditions for second-order linear hyperbolic equations is proposed. The nonlocal boundary condition is given by a pseudodifferential operator that annihilates travelling waves. It is obtained through the dispersion relation of the differential equation by requiring that the initial-boundary value problem admits the wave solutions travelling in one direction only. Local approximation of this global boundary condition yields an nth-order differential operator. It is shown that the best approximations must be in the canonical forms which can be factorized into first-order operators. These boundary conditions are perfectly absorbing for wave packets propagating at certain group velocities. A hierarchy of absorbing boundary conditions is derived for transonic small perturbation equations of unsteady flows. These examples illustrate that the absorbing boundary conditions are easy to derive, and the effectiveness is demonstrated by the numerical experiments.

  5. [Study on absorbing volatile oil with mesoporous carbon].

    PubMed

    Yan, Hong-mei; Jia, Xiao-bin; Zhang, Zhen-hai; Sun, E; Yang Nan

    2014-11-01

    Clove oil and turmeric oil were absorbed by mesoporous carbon. The absorption ratio of mesoporous carbon to volatile oil was optimized with the eugenol yield and curcumol yield as criteria Curing powder was characterized by scanning electron microscopy (SEM) and differential scanning calorietry (DSC). The effects of mesoporous carbon on dissolution in vitro and thermal stability of active components were studied. They reached high adsorption rate when the absorption ratio of mesoporous carbon to volatile oil was 1:1. When volatile oil was absorbed, dissolution rate of active components had a little improvement and their thermal stability improved after volatile oil was absorbed by the loss rate decreasing more than 50%. Absorbing herbal volatile oil with mesoporous carbon deserves further studying. PMID:25850263

  6. 83. Shock absorber attaching "egg" to the launch control center, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    83. Shock absorber attaching "egg" to the launch control center, southwest corner - Ellsworth Air Force Base, Delta Flight, Launch Control Facility, County Road CS23A, North of Exit 127, Interior, Jackson County, SD

  7. 14. Missile thrusters, missile resting on ring, shock absorber attachments ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    14. Missile thrusters, missile resting on ring, shock absorber attachments at three points - Ellsworth Air Force Base, Delta Flight, Launch Facility, On County Road T512, south of Exit 116 off I-90, Interior, Jackson County, SD

  8. 48. Bottom of shock absorber, bottom of launch tube, soda ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    48. Bottom of shock absorber, bottom of launch tube, soda bottle liter at right - Ellsworth Air Force Base, Delta Flight, Launch Facility, On County Road T512, south of Exit 116 off I-90, Interior, Jackson County, SD

  9. 86. Shock absorber, top of launch control center, southeast corner ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    86. Shock absorber, top of launch control center, southeast corner - Ellsworth Air Force Base, Delta Flight, Launch Control Facility, County Road CS23A, North of Exit 127, Interior, Jackson County, SD

  10. 21 CFR 878.4830 - Absorbable surgical gut suture.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... absorbable, sterile, flexible thread prepared from either the serosal connective tissue layer of beef (bovine) or the submucosal fibrous tissue of sheep (ovine) intestine, and is intended for use in soft...

  11. 21 CFR 878.4830 - Absorbable surgical gut suture.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... absorbable, sterile, flexible thread prepared from either the serosal connective tissue layer of beef (bovine) or the submucosal fibrous tissue of sheep (ovine) intestine, and is intended for use in soft...

  12. 21 CFR 878.4830 - Absorbable surgical gut suture.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... absorbable, sterile, flexible thread prepared from either the serosal connective tissue layer of beef (bovine) or the submucosal fibrous tissue of sheep (ovine) intestine, and is intended for use in soft...

  13. 21 CFR 878.4830 - Absorbable surgical gut suture.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... absorbable, sterile, flexible thread prepared from either the serosal connective tissue layer of beef (bovine) or the submucosal fibrous tissue of sheep (ovine) intestine, and is intended for use in soft...

  14. Stretchable Metamaterial Absorber Using Liquid Metal-Filled Polydimethylsiloxane (PDMS).

    PubMed

    Kim, Kyeongseob; Lee, Dongju; Eom, Seunghyun; Lim, Sungjoon

    2016-01-01

    A stretchable metamaterial absorber is proposed in this study. The stretchability was achieved by liquid metal and polydimethylsiloxane (PDMS). To inject liquid metal, microfluidic channels were fabricated using PDMS powers and microfluidic-channel frames, which were built using a three-dimensional printer. A top conductive pattern and ground plane were designed after considering the easy injection of liquid metal. The proposed metamaterial absorber comprises three layers of PDMS substrate. The top layer is for the top conductive pattern, and the bottom layer is for the meandered ground plane. Flat PDMS layers were inserted between the top and bottom PDMS layers. The measured absorptivity of the fabricated absorber was 97.8% at 18.5 GHz, and the absorption frequency increased from 18.5 to 18.65 GHz as the absorber was stretched from its original length (5.2 cm) to 6.4 cm. PMID:27077861

  15. Techniques for measuring intercepted and absorbed PAR in corn canopies

    NASA Technical Reports Server (NTRS)

    Gallo, K. P.; Daughtry, C. S. T.

    1984-01-01

    The quantity of radiation potentially available for photosynthesis that is captured by the crop is best described as absorbed photosynthetically active radiation (PAR). Absorbed PAR (APAR) is the difference between descending and ascending fluxes. The four components of APAR were measured above and within two planting densities of corn (Zea mays L.) and several methods of measuring and estimating APAR were examined. A line quantum sensor that spatially averages the photosynthetic photon flux density provided a rapid and portable method of measuring APAR. PAR reflectance from the soil (Typic Argiaquoll) surface decreased from 10% to less than 1% of the incoming PAR as the canopy cover increased. PAR reflectance from the canopy decreased to less than 3% at maximum vegetative cover. Intercepted PAR (1 - transmitted PAR) generally overestimated absorbed PAR by less than 4% throughout most of the growing season. Thus intercepted PAR appears to be a reasonable estimate of absorbed PAR.

  16. 21 CFR 878.4840 - Absorbable polydioxanone surgical suture.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... (CONTINUED) MEDICAL DEVICES GENERAL AND PLASTIC SURGERY DEVICES Surgical Devices § 878.4840 Absorbable... expected to occur, and ophthalmic surgery. It may be coated or uncoated, undyed or dyed, and with...

  17. 21 CFR 878.4840 - Absorbable polydioxanone surgical suture.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... (CONTINUED) MEDICAL DEVICES GENERAL AND PLASTIC SURGERY DEVICES Surgical Devices § 878.4840 Absorbable... expected to occur, and ophthalmic surgery. It may be coated or uncoated, undyed or dyed, and with...

  18. 21 CFR 878.4840 - Absorbable polydioxanone surgical suture.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... (CONTINUED) MEDICAL DEVICES GENERAL AND PLASTIC SURGERY DEVICES Surgical Devices § 878.4840 Absorbable... expected to occur, and ophthalmic surgery. It may be coated or uncoated, undyed or dyed, and with...

  19. 21 CFR 878.4840 - Absorbable polydioxanone surgical suture.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... (CONTINUED) MEDICAL DEVICES GENERAL AND PLASTIC SURGERY DEVICES Surgical Devices § 878.4840 Absorbable... expected to occur, and ophthalmic surgery. It may be coated or uncoated, undyed or dyed, and with...

  20. Liquid absorbent solutions for separating nitrogen from natural gas

    DOEpatents

    Friesen, Dwayne T.; Babcock, Walter C.; Edlund, David J.; Lyon, David K.; Miller, Warren K.

    2000-01-01

    Nitrogen-absorbing and -desorbing compositions, novel ligands and transition metal complexes, and methods of using the same, which are useful for the selective separation of nitrogen from other gases, especially natural gas.