WorldWideScience

Sample records for free-standing top solar

  1. Free-standing inflatable solar chimney: experiment and theory

    Science.gov (United States)

    Vorobieff, Peter; Mammoli, Andrea; Fathi, Nima; Putkaradze, Vakhtang

    2014-11-01

    Solar chimneys (or solar updraft towers) offer an attractive way to use solar energy for production of baseload power. In a power plant of this type, sunshine heats the air under a wide greenhouse-like roofed collector surrounding the central base of a tall chimney. The heated air drives an updraft flow through the tower, whose energy is harvested with turbines. For a sufficiently large plant of this type, the thermal mass of the heated ground under the collector is sufficient to drive the flow even when the sun is down. The primary challenge in building the solar chimney power plant is the construction of the chimney that generates the updraft, which must be very tall (hundreds of meters for a commercial-sized plant). Here we present a study of an inflatable chimney which is a self-supporting, deformable, free-standing stack of gas-filled tori. The structure is stabilized via a combination of shape, overpressure, and buoyancy. Theoretical considerations suggest that filling the tori with air rather than with a light gas may be advantageous for stability. The chimney shape is optimized for deformation under wind loading. A prototype chimney has demonstrated the viability of the concept, with experimental results in good agreement with theoretical predictions. This research is partially supported by the UNM Research Allocations Comittee (RAC) and UNM Center for Emerging Energy Technologies (CEET).

  2. A top-down approach for fabricating free-standing bio-carbon supercapacitor electrodes with a hierarchical structure

    OpenAIRE

    Yingzhi Li; Qinghua Zhang; Junxian Zhang; Lei Jin; Xin Zhao; Ting Xu

    2015-01-01

    Biomass has delicate hierarchical structures, which inspired us to develop a cost-effective route to prepare electrode materials with rational nanostructures for use in high-performance storage devices. Here, we demonstrate a novel top-down approach for fabricating bio-carbon materials with stable structures and excellent diffusion pathways; this approach is based on carbonization with controlled chemical activation. The developed free-standing bio-carbon electrode exhibits a high specific ca...

  3. Free-standing chiral plasmonics

    Science.gov (United States)

    Leong, Eunice Sok Ping; Deng, Jie; Wu, Siji; Khoo, Eng Huat; Liu, Yan Jun

    2014-11-01

    Chiral plasmonic nanostructures offer the ability to achieve strong optical circular dichroism (CD) activity over a broad spectral range, which has been challenging for chiral molecules. Chiral plasmonic nanostructures have been extensively studied based on top-down and bottom-up fabrication techniques. Particularly, in the top-down electron-beam lithography, 3D plasmonic nanostructure fabrication involves layer-by-layer patterning and complex alignment, which is time-consuming and causes many defects in the structures. Here, we present a free-standing 3D chiral plamonic nanostructures using the electron-beam lithography technique with much simplified fabrication processes. The 3D chiral plasmonic nanostructures consist of a free-standing ultrathin silicon nitride membrane with well-aligned L-shape metal nanostructures on one side and disk-shape ones on the other side. The free-standing membrane provides an ultra-smooth metal/dielectric interface and uniformly defines the gap between the upper and lower layers in an array of chiral nanostructures. Such free-standing chiral plasmonic nanostructures exhibit strong CD at optical frequencies, which can be engineered by simply changing the disk size on one side of the membrane. Experimental results are in good agreement with the finite-difference time-domain simulations. Such free-standing chiral plasmonics holds great potential for chirality analysis of biomolecules, drugs, and chemicals.

  4. FREE STANDING FILM OF POLYANILINE

    Institute of Scientific and Technical Information of China (English)

    WAN Meixiang; CAO Yong; LI Junchao; ZHOU Weixia; LI Suzhen

    1991-01-01

    A free standing film of polyaniline as large as 18cm×18cm×0.002cm can be obtained by evaporation of a solution of the chemically synthesized base in NMP. Its structure was examined by the elemental analysis, IR, U.V.-visible spectra, XPS, DSC, SEM and X-ray scattering and its conducting behavior as well as electrochemical properties were studied. Results show that the composition, structure of main chain, physical properties of the free standing tilm of polyaniline is similar to that of the powder. However, some differences in its electronic structure, conductivity at room temperature and potential of redox couple between the free standing film and powder are observed,which may be due to cross-linking of the film of polyaniline.

  5. Template-assisted fabrication of free-standing nanorod arrays of a hole-conducting cross-linked triphenylamine derivative: toward ordered bulk-heterojunction solar cells.

    Science.gov (United States)

    Haberkorn, Niko; Gutmann, Jochen S; Theato, Patrick

    2009-06-23

    Free-standing nanorod arrays of a thermally cross-linked semiconducting triphenylamine were fabricated on conductive ITO/glass substrates via an anodic aluminum oxide (AAO) template-assisted approach. By using a solution wetting method combined with a subsequent thermal imprinting step to fill the nanoporous structure of the template with a cross-linkable triphenylamine derivative, a polymeric replication of the AAO was obtained after thermal curing and selective removal of the template. To obtain well-aligned and free-standing nanorod arrays, aggregation and collapse of the nanorods were prevented by optimizing their aspect ratio and applying a freeze-drying technique to remove the aqueous medium after the etching step. Because of their electrochemical properties and their resistance against organic solvents after curing, these high density nanorod arrays have potential application in organic photovoltaics.

  6. Free-standing oxide superconducting articles

    Science.gov (United States)

    Wu, Xin D.; Muenchausen, Ross E.

    1993-01-01

    A substrate-free, free-standing epitaxially oriented superconductive film including a layer of a template material and a layer of a ceramic superconducting material is provided together with a method of making such a substrate-free ceramic superconductive film by coating an etchable material with a template layer, coating the template layer with a layer of a ceramic superconductive material, coating the layer of ceramic superconductive material with a protective material, removing the etchable material by an appropriate means so that the etchable material is separated from a composite structure including the template lay This invention is the result of a contract with the Department of Energy (Contract No. W-7405-ENG-36).

  7. All-solution processed organic solar cells with top illumination

    NARCIS (Netherlands)

    Patil, B.R.; Shanmugam, S.; Teunissen, J.P.; Galagan, Y.

    2015-01-01

    All-solution processed organic solar cells with inverted device architecture were demonstrated. Devices contain opaque bottom electrodes and semitransparent top electrodes, resulting in top illuminated devices. Nanoparticles-based Ag ink was used for inkjet printing both top and bottom electrodes.

  8. All-solution processed organic solar cells with top illumination

    NARCIS (Netherlands)

    Patil, B.R.; Shanmugam, S.; Teunissen, J.P.; Galagan, Y.

    2015-01-01

    All-solution processed organic solar cells with inverted device architecture were demonstrated. Devices contain opaque bottom electrodes and semitransparent top electrodes, resulting in top illuminated devices. Nanoparticles-based Ag ink was used for inkjet printing both top and bottom electrodes. S

  9. Controlled electromigration and oxidation of free-standing copper wires

    Science.gov (United States)

    Hauser, J. S.; Schwichtenberg, J.; Marz, M.; Sürgers, C.; Seiler, A.; Gerhards, U.; Messerschmidt, F.; Hensel, A.; Dittmeyer, R.; Löhneysen, H. v.; Hoffmann-Vogel, R.

    2016-12-01

    We have studied controlled electromigration (EM) in free-standing copper wires. Besides electrical characterization by voltage-current measurements, structural analyses have been performed by means of scanning electron microscopy and cross-sectional microprobe measurements. We have found that oxidation during the EM in air stabilizes the free-standing wire against uncontrolled blowing, making it possible to thin the conductive part of the wire down to a conductance of a few conductance quanta G_0=2e^2{/}h. The decisive influence of oxidation by air on the EM process was confirmed by control experiments performed under ultra-high vacuum conditions. In line with these findings, free-standing Au wires were difficult to thin down reproducibly to a conductance of a few G_0. Estimates of the local temperature in the free-standing wire are obtained from finite element method calculations.

  10. Electron-phonon coupling in quasi free-standing graphene

    DEFF Research Database (Denmark)

    Christian Johannsen, Jens; Ulstrup, Søren; Bianchi, Marco

    2013-01-01

    Quasi free-standing monolayer graphene can be produced by intercalating species like oxygen or hydrogen between epitaxial graphene and the substrate crystal. If the graphene is indeed decoupled from the substrate, one would expect the observation of a similar electronic dispersion and many......-body effects, irrespective of the substrate and the material used to achieve the decoupling. Here we investigate the electron-phonon coupling in two different types of quasi free-standing monolayer graphene: decoupled from SiC via hydrogen intercalation and decoupled from Ir via oxygen intercalation. Both...

  11. Electron-phonon coupling in quasi free-standing graphene

    DEFF Research Database (Denmark)

    Christian Johannsen, Jens; Ulstrup, Søren; Bianchi, Marco;

    2013-01-01

    Quasi free-standing monolayer graphene can be produced by intercalating species like oxygen or hydrogen between epitaxial graphene and the substrate crystal. If the graphene is indeed decoupled from the substrate, one would expect the observation of a similar electronic dispersion and many......-body effects, irrespective of the substrate and the material used to achieve the decoupling. Here we investigate the electron-phonon coupling in two different types of quasi free-standing monolayer graphene: decoupled from SiC via hydrogen intercalation and decoupled from Ir via oxygen intercalation. Both...

  12. Customizable nanotweezers for manipulation of free-standing nanostructures

    DEFF Research Database (Denmark)

    Bøggild, Peter; Hansen, Torben Mikael; Mølhave, Kristian

    2001-01-01

    We present a novel nanotweezer device for manipulation and measurement of free-standing nanostructures, where the shape of the tweezer tips can be customized for the application. Electrostatic actuators with submicron interelectrode spacings are fabricated on a batch level using silicon microfabr......We present a novel nanotweezer device for manipulation and measurement of free-standing nanostructures, where the shape of the tweezer tips can be customized for the application. Electrostatic actuators with submicron interelectrode spacings are fabricated on a batch level using silicon...... of the cantilevers, leading to the formation of 40-100 nm diameter carbon-based tips. Careful alignment of the substrate and the beam, as well as proper selection of growth mode, results in converging tips forming nanogaps down to 20 nm. The nanotweezers can be metallized to be used for electrical measurements...

  13. Current injection to free-standing III-N nanowires by bipolar diffusion

    Science.gov (United States)

    Kivisaari, Pyry; Oksanen, Jani; Tulkki, Jukka

    2013-07-01

    Light-emitting diodes (LEDs) based on nanowires are expected to enable a superior alternative to conventional LEDs due to their higher light extraction efficiency, reduced droop, and reduced material consumption. However, efficient current injection to nanowires with conventional current spreading approaches is challenging, because the conventional approach requires doping the wires and using at least partly absorbing top contacts. We show that minority carrier diffusion provides an extremely interesting possibility for current injection to undoped free-standing nanowires that do not require top contacts. To investigate this possibility, we have simulated current transport in selected nanowire structures where the nanowires are located close to a separate pn homojunction. Our results suggest that with bipolar diffusion injection, injection efficiencies exceeding 80% are feasible even for unoptimized free-standing nanowire structures at current densities up to 100 A/cm2, with a maximum injection efficiency of approximately 95% at 0.1 A/cm2. The results suggest that the concept also extends to other near surface nanostructures such as quantum wells coupled to surface plasmons and, under reverse operation, to photovoltaic devices.

  14. GAS SEPARATION PROPERTIES OF FREE STANDING FILM OF POLYANILINE

    Institute of Scientific and Technical Information of China (English)

    YANG Jiping; SUN Qiushi; HOU Xiaohuai; WAN Meixiang

    1993-01-01

    The gas separation properties of free standing film of polyaniline (PANI) for gas pairs of He/N2,H2/N2,CO2/N2 and CO2/CH4 at room temperature were measured as a function of the protonation state.Variation of the gas permeabilities coefficient of PANI with an insulator to metal transition upon the protonation processes was observed,which might be due to a change in both gas solubility coefficient and diffusion coefficient with the protonation state.

  15. Multimode laser emission from free-standing cylindrical microcavities

    Energy Technology Data Exchange (ETDEWEB)

    Peter, Jaison, E-mail: jaisonpeter@cusat.ac.in; Radhakrishnan, P.; Nampoori, V.P.N.; Kailasnath, M.

    2014-05-01

    We report a well resolved whispering gallery mode (WGM) laser emission from a free-standing microring cavity based on a dye doped hollow polymer optical fiber (DDHPOF), which is transversely pumped by a pulsed Nd:YAG laser. The microring laser is characterized by a well-defined, low threshold pump power at which the emission spectral intensity dramatically increases and collapses into several dominant microcavity laser modes with reduced mode spacing and high Q-value. Resonant modes are excited inside the gain medium which is strongly confined along the radial direction so that the spacing of lasing modes is controlled by the diameter of the cylindrical microcavity. A variation in the free spectral range of WGM spectra from 0.23 to 0.09 nm coupled with a red-shift is observed with an increase in the diameter of DDHPOFs. - Highlights: • Different diameter free-standing cylindrical microcavity lasers have been fabricated and their performances have been evaluated. • The microring laser is characterized by a well-defined, low threshold pump power, with reduced mode spacing and high Q-value. • When the diameter of DDHPOF increases, the number of lasing peaks increases along with the decrease of the FSR as observed from our studies. • It is also found that whispering gallery lasing envelope is shifted from 559 to 571 nm (Stokes shift) with the diameter.

  16. Free-standing arrays of isolated TiO2 nanotubes through supercritical fluid drying.

    Science.gov (United States)

    Deneault, James R; Xiao, Xiaoyin; Kang, Tae-Sik; Wang, Joanna S; Wai, Chien M; Brown, Gail J; Durstock, Michael F

    2012-01-16

    A common complication in fabricating arrays of TiO(2) nanotubes is that they agglomerate into tightly packed bundles during the inevitable solvent evaporation step. This problem is particularly acute for template-fabricated TiO(2) nanotubes, as the geometric tunability of this technique enables relatively large inter-pore spacings or, from another perspective, more space for lateral displacement. Our work showed that agglomeration results from the surface tension forces that are present as the ambient solvent is evaporated from the nanotube film. Herein, we report a processing and fabrication approach that utilizes supercritical fluid drying (CO(2)) to prepare arrays of template-fabricated TiO(2) nanotubes that are free-standing and spatially isolated. This approach could be beneficial to many emerging technologies, such as solid-state dye-sensitized solar cells and vertically-oriented carbon nanotube electrodes.

  17. Ternary semitransparent organic solar cells with a laminated top electrode

    Science.gov (United States)

    Makha, Mohammed; Testa, Paolo; Anantharaman, Surendra Babu; Heier, Jakob; Jenatsch, Sandra; Leclaire, Nicolas; Tisserant, Jean-Nicolas; Véron, Anna C.; Wang, Lei; Nüesch, Frank; Hany, Roland

    2017-01-01

    Abstract Tinted and colour-neutral semitransparent organic photovoltaic elements are of interest for building-integrated applications in windows, on glass roofs or on facades. We demonstrate a semitransparent organic photovoltaic cell with a dry-laminated top electrode that achieves a uniform average visible transmittance of 51% and a power conversion efficiency of 3%. The photo-active material is based on a majority blend composed of a visibly absorbing donor polymer and a fullerene acceptor, to which a selective near-infrared absorbing cyanine dye is added as a minority component. Our results show that organic ternary blends are attractive for the fabrication of semitransparent solar cells in general, because a guest component with a complementary absorption can compensate for the inevitably reduced current generation capability of a high-performing binary blend when applied as a thin, semitransparent film. PMID:28179960

  18. Ternary semitransparent organic solar cells with a laminated top electrode.

    Science.gov (United States)

    Makha, Mohammed; Testa, Paolo; Anantharaman, Surendra Babu; Heier, Jakob; Jenatsch, Sandra; Leclaire, Nicolas; Tisserant, Jean-Nicolas; Véron, Anna C; Wang, Lei; Nüesch, Frank; Hany, Roland

    2017-01-01

    Tinted and colour-neutral semitransparent organic photovoltaic elements are of interest for building-integrated applications in windows, on glass roofs or on facades. We demonstrate a semitransparent organic photovoltaic cell with a dry-laminated top electrode that achieves a uniform average visible transmittance of 51% and a power conversion efficiency of 3%. The photo-active material is based on a majority blend composed of a visibly absorbing donor polymer and a fullerene acceptor, to which a selective near-infrared absorbing cyanine dye is added as a minority component. Our results show that organic ternary blends are attractive for the fabrication of semitransparent solar cells in general, because a guest component with a complementary absorption can compensate for the inevitably reduced current generation capability of a high-performing binary blend when applied as a thin, semitransparent film.

  19. Squeezing-out dynamics in free-standing smectic films

    Energy Technology Data Exchange (ETDEWEB)

    S̀liwa, Izabela, E-mail: izasliwa@ifmpan.poznan.pl [Institute of Molecular Physics, Polish Academy of Sciences, Smoluchowskiego 17, 60-179 Poznaǹ (Poland); Vakulenko, A.A. [Saint Petersburg Institute for Machine Sciences, The Russian Academy of Sciences, Saint Petersburg 199178 (Russian Federation); Zakharov, A.V., E-mail: alexandre.zakharov@yahoo.ca [Saint Petersburg Institute for Machine Sciences, The Russian Academy of Sciences, Saint Petersburg 199178 (Russian Federation)

    2016-05-06

    Highlights: • We model the dynamics of layer transitions. • We model the thermally activated nucleation of a small hole. • We model the dynamics of squeezing-out one layer. - Abstract: We have carried out a theoretical study of the dynamics of the squeezing-out of one layer from the N-layer free-standing smectic film (FSSF) coupled with a meniscus, during the layer-thinning process. Squeezing-out is initiated by a thermally activated nucleation process in which a density fluctuation forms a small void in the center of the circular FSSF. The pressure gradient develops between the squeezed-out and nonsqueezed-out areas and is responsible for the driving out of one or several layer(s) from the N-layer smectic film. The dynamics of the boundary between these areas in the FSSF is studied by the use of the conservation laws for mass and linear momentum with accounting for the coupling between the meniscus and the smectic film. This coupling has a strong effect on the dynamics of the squeezing-out process and may significantly change the time which is needed to completely squeezed-out one or several layer(s) from the N-layer smectic film.

  20. Optical reflectance in free-standing smectic films

    Science.gov (United States)

    Śliwa, Izabela

    2016-03-01

    We have carried out a numerical study of the structural, thermodynamic and optical properties of the partially fluorinated 5-n-alkyl-2-(4-n-(perfluoroalkyl-metheleneoxy)phenyl) free-standing smectic film in air under the action of the external electric field E. Calculations, based upon the extended McMillan‧s mean-field theory with anisotropic forces, show a stepwise reduction of the value of the Helmholtz free energy and the reflectivity of the partially fluorinated smectic film in air, as the temperature is raised above the bulk smectic-A-isotropic transition value. It has been shown, by solving the self-consistent nonlinear equations for the orientational and translational order parameters, that the electric field E may not only affect the layer-thinning transition sequences, but also change the first multilayer jump in the film thickness, whereas practically does not affect the reflectivity of the partially fluorinated smectic film in air. The partially fluorinated LC compounds reveal a compression of a smectic layer spacing during the layer-thinning transitions which is supported by the negative values of the thermal expansion coefficient.

  1. Preparation and characterization of free-standing pure porphyrin nanoparticles

    Indian Academy of Sciences (India)

    Arun Kumar Perepogu; Prakriti Ranjan Bangal

    2008-09-01

    Preparation and characterization of absolutely pure and stable nanoparticles of 5,10,15,20-meso-tetrakis phenyl porphyrin (TPP) and catalytically repute 5,10,15,20-meso-tetrakis pentaflurophenyl porphyrin (H2F20TPP) by improved ‘reprecipitation method’ is described. The innovation of this modified `reprecipitation method’ lies on the judicial selection of organic solvent and amount of porphyrin solution to be injected in the aqueous media. Exactly similar process produces relatively small nanoparticles for TPP than that of H2F20TPP while the stability of the H2F20TPP nanoparticles is bit higher than nanoparticles of TPP. Absorption and emission spectra reveal that the formation of nanoparticles for both the cases is induced by J- and H-type aggregation. DFT calculations predict the optimized geometries and frontier molecular orbital, which favours the strength of face-to-face interaction with neighbour molecules to be more facile for TPP than that of H2F20TPP helping the latter to form bigger and relatively more stable and free-standing nanoparticles. The use of no other compounds except dichloromethane, a highly volatile organic solvent and respective porphyrins give absolutely pure nanoparticles. This improved method will lead to produce organic nanoparticles of -conjugated systems easily and efficiently.

  2. Perovskite solar cells: On top of commercial photovoltaics

    Science.gov (United States)

    Albrecht, Steve; Rech, Bernd

    2017-01-01

    The efficiency of single-junction solar cells is intrinsically limited and high efficiency multi-junctions are not cost effective yet. Now, semi-transparent perovskite solar cells suggest that low cost multi-junctions could be within reach.

  3. Solar Energetic Particle Spectrum on 2006 December 13 Determined by IceTop

    Science.gov (United States)

    Abbasi, R.; Ackermann, M.; Adams, J.; Ahlers, M.; Ahrens, J.; Andeen, K.; Auffenberg, J.; Bai, X.; Baker, M.; Baret, B.; Barwick, S. W.; Bay, R.; Bazo Alba, J. L.; Beattie, K.; Becka, T.; Becker, J. K.; Becker, K. H.; Berghaus, P.; Berley, D.; Bernardini, E.; Bertrand, D.; Besson, D. Z.; Bieber, J. W.; Blaufuss, E.; Boersma, D. J.; Bohm, C.; Bolmont, J.; Böser, S.; Botner, O.; Braun, J.; Breder, D.; Burgess, T.; Castermans, T.; Chirkin, D.; Christy, B.; Clem, J.; Cowen, D. F.; D'Agostino, M. V.; Danninger, M.; Davour, A.; Day, C. T.; De Clercq, C.; Demirörs, L.; Depaepe, O.; Descamps, F.; Desiati, P.; de Vries-Uiterweerd, G.; DeYoung, T.; Diaz-Velez, J. C.; Dreyer, J.; Dumm, J. P.; Duvoort, M. R.; Edwards, W. R.; Ehrlich, R.; Eisch, J.; Ellsworth, R. W.; Engdegaard, O.; Euler, S.; Evenson, P. A.; Fadiran, O.; Fazely, A. R.; Filimonov, K.; Finley, C.; Foerster, M. M.; Fox, B. D.; Franckowiak, A.; Franke, R.; Gaisser, T. K.; Gallagher, J.; Ganugapati, R.; Gerhardt, L.; Gladstone, L.; Goldschmidt, A.; Goodman, J. A.; Gozzini, R.; Grant, D.; Griesel, T.; Gross, A.; Grullon, S.; Gunasingha, R. M.; Gurtner, M.; Ha, C.; Hallgren, A.; Halzen, F.; Han, K.; Hanson, K.; Hardtke, D.; Hardtke, R.; Hasegawa, Y.; Heise, J.; Helbing, K.; Hellwig, M.; Herquet, P.; Hickford, S.; Hill, G. C.; Hoffman, K. D.; Hoshina, K.; Hubert, D.; Hülss, J. P.; Hulth, P. O.; Hultqvist, K.; Hundertmark, S.; Imlay, R. L.; Inaba, M.; Ishihara, A.; Jacobsen, J.; Japaridze, G. S.; Johansson, H.; Joseph, J. M.; Kampert, K. H.; Kappes, A.; Karg, T.; Karle, A.; Kawai, H.; Kelley, J. L.; Kiryluk, J.; Kislat, F.; Klein, S. R.; Klepser, S.; Kohnen, G.; Kolanoski, H.; Köpke, L.; Kowalski, M.; Kowarik, T.; Krasberg, M.; Kuehn, K.; Kuwabara, T.; Labare, M.; Laihem, K.; Landsman, H.; Lauer, R.; Leich, H.; Leier, D.; Lucke, A.; Lundberg, J.; Lünemann, J.; Madsen, J.; Maruyama, R.; Mase, K.; Matis, H. S.; McParland, C. P.; Meagher, K.; Meli, A.; Merck, M.; Messarius, T.; Mészáros, P.; Miyamoto, H.; Mohr, A.; Montaruli, T.; Morse, R.; Movit, S. M.; Münich, K.; Nahnhauer, R.; Nam, J. W.; Niessen, P.; Nygren, D. R.; Odrowski, S.; Olivas, A.; Olivo, M.; Ono, M.; Panknin, S.; Patton, S.; Pérez de los Heros, C.; Petrovic, J.; Piegsa, A.; Pieloth, D.; Pohl, A. C.; Porrata, R.; Potthoff, N.; Pretz, J.; Price, P. B.; Przybylski, G. T.; Pyle, R.; Rawlins, K.; Razzaque, S.; Redl, P.; Resconi, E.; Rhode, W.; Ribordy, M.; Rizzo, A.; Robbins, W. J.; Rodrigues, J.; Roth, P.; Rothmaier, F.; Rott, C.; Roucelle, C.; Rutledge, D.; Ryckbosch, D.; Sander, H. G.; Sarkar, S.; Satalecka, K.; Schlenstedt, S.; Schmidt, T.; Schneider, D.; Schultz, O.; Seckel, D.; Semburg, B.; Seo, S. H.; Sestayo, Y.; Seunarine, S.; Silvestri, A.; Smith, A. J.; Song, C.; Spiczak, G. M.; Spiering, C.; Stanev, T.; Stezelberger, T.; Stokstad, R. G.; Stoufer, M. C.; Stoyanov, S.; Strahler, E. A.; Straszheim, T.; Sulanke, K. H.; Sullivan, G. W.; Swillens, Q.; Taboada, I.; Tarasova, O.; Tepe, A.; Ter-Antonyan, S.; Tilav, S.; Tluczykont, M.; Toale, P. A.; Tosi, D.; Turcan, D.; van Eijndhoven, N.; Vandenbroucke, J.; Van Overloop, A.; Viscomi, V.; Vogt, C.; Voigt, B.; Walck, C.; Waldenmaier, T.; Waldmann, H.; Walter, M.; Wendt, C.; Westerhoff, S.; Whitehorn, N.; Wiebusch, C. H.; Wiedemann, C.; Wikström, G.; Williams, D. R.; Wischnewski, R.; Wissing, H.; Woschnagg, K.; Xu, X. W.; Yodh, G.; Yoshida, S.

    2008-12-01

    On 2006 December 13 the IceTop air shower array at the South Pole detected a major solar particle event. By numerically simulating the response of the IceTop tanks, which are thick Cerenkov detectors with multiple thresholds deployed at high altitude with no geomagnetic cutoff, we determined the particle energy spectrum in the energy range 0.6-7.6 GeV. This is the first such spectral measurement using a single instrument with a well-defined viewing direction. We compare the IceTop spectrum and its time evolution with previously published results and outline plans for improved resolution of future solar particle spectra.

  4. Solar water disinfection (SODIS): A review from bench-top to roof-top

    Energy Technology Data Exchange (ETDEWEB)

    McGuigan, Kevin G., E-mail: kmcguigan@rcsi.ie [Royal College of Surgeons in Ireland, Dublin 2 (Ireland); Conroy, Ronan M. [Royal College of Surgeons in Ireland, Dublin 2 (Ireland); Mosler, Hans-Joachim [EAWAG, Swiss Federal Institute of Aquatic Science and Technology, Ueberlandstrasse 133: CH-8600 Duebendorf (Switzerland); Preez, Martella du; Ubomba-Jaswa, Eunice [CSIR, Natural Resources and the Environment, Pretoria, Gauteng (South Africa); Fernandez-Ibanez, Pilar [Plataforma Solar de Almeria - CIEMAT, P.O. Box 22, 07200 Tabernas, Almeria (Spain)

    2012-10-15

    Graphical abstract: . Water being treated by solar disinfection outside a primary school classroom in Southern Uganda. Students fill their bottles at home and expose them to the sun while they are at school. Highlights: Black-Right-Pointing-Pointer A thorough review of current state of play of solar water disinfection. Black-Right-Pointing-Pointer An examination of both laboratory and field studies. Black-Right-Pointing-Pointer Description of the economic and behaviour change aspects of this technology. - Abstract: Solar water disinfection (SODIS) has been known for more than 30 years. The technique consists of placing water into transparent plastic or glass containers (normally 2 L PET beverage bottles) which are then exposed to the sun. Exposure times vary from 6 to 48 h depending on the intensity of sunlight and sensitivity of the pathogens. Its germicidal effect is based on the combined effect of thermal heating of solar light and UV radiation. It has been repeatedly shown to be effective for eliminating microbial pathogens and reduce diarrhoeal morbidity including cholera. Since 1980 much research has been carried out to investigate the mechanisms of solar radiation induced cell death in water and possible enhancement technologies to make it faster and safer. Since SODIS is simple to use and inexpensive, the method has spread throughout the developing world and is in daily use in more than 50 countries in Asia, Latin America, and Africa. More than 5 million people disinfect their drinking water with the solar disinfection (SODIS) technique. This review attempts to revise all relevant knowledge about solar disinfection from microbiological issues, laboratory research, solar testing, up to and including real application studies, limitations, factors influencing adoption of the technique and health impact.

  5. Solar water disinfection (SODIS): a review from bench-top to roof-top.

    Science.gov (United States)

    McGuigan, Kevin G; Conroy, Ronán M; Mosler, Hans-Joachim; du Preez, Martella; Ubomba-Jaswa, Eunice; Fernandez-Ibañez, Pilar

    2012-10-15

    Solar water disinfection (SODIS) has been known for more than 30 years. The technique consists of placing water into transparent plastic or glass containers (normally 2L PET beverage bottles) which are then exposed to the sun. Exposure times vary from 6 to depending on the intensity of sunlight and sensitivity of the pathogens. Its germicidal effect is based on the combined effect of thermal heating of solar light and UV radiation. It has been repeatedly shown to be effective for eliminating microbial pathogens and reduce diarrhoeal morbidity including cholera. Since 1980 much research has been carried out to investigate the mechanisms of solar radiation induced cell death in water and possible enhancement technologies to make it faster and safer. Since SODIS is simple to use and inexpensive, the method has spread throughout the developing world and is in daily use in more than 50 countries in Asia, Latin America, and Africa. More than 5 million people disinfect their drinking water with the solar disinfection (SODIS) technique. This review attempts to revise all relevant knowledge about solar disinfection from microbiological issues, laboratory research, solar testing, up to and including real application studies, limitations, factors influencing adoption of the technique and health impact. Copyright © 2012 Elsevier B.V. All rights reserved.

  6. A three solar cell system based on a self-supporting, transparent AlGaAs top solar cell

    Science.gov (United States)

    Negley, Gerald H.; Rhoads, Sandra L.; Terranova, Nancy E.; Mcneely, James B.; Barnett, Allen M.

    1989-01-01

    Development of a three solar cell stack can lead to practical efficiencies greater than 30 percent (1x,AM0). A theoretical efficiency limitation of 43.7 percent at AM0 and one sun is predicted by this model. Including expected losses, a practical system efficiency of 36.8 percent is anticipated. These calculations are based on a 1.93eV/1.43eV/0.89eV energy band gap combination. AlGaAs/GaAs/GaInAsP materials can be used with a six-terminal wiring configuration. The key issues for multijunction solar cells are the top and middle solar cell performance and the sub-bandgap transparency. AstroPower has developed a technique to fabricate AlGaAs solar cells on rugged, self-supporting, transparent AlGaAs substrates. Top solar cell efficiencies greater than 11 percent AM0 have been achieved. State-of-the-art GaAs or InP devices will be used for the middle solar cell. GaInAsP will be used to fabricate the bottom solar cell. This material is lattice-matched to InP and offers a wide range of bandgaps for optimization of the three solar cell stack. Liquid phase epitaxy is being used to grow the quaternary material. Initial solar cells have shown open-circuit voltages of 462 mV for a bandgap of 0.92eV. Design rules for the multijunction three solar cell stack are discussed. The progress in the development of the self-supporting AlGaAs top solar cell and the GaInAsP bottom solar cell is presented.

  7. An optimized top contact design for solar cell concentrators

    Science.gov (United States)

    Desalvo, Gregory C.; Barnett, Allen M.

    1985-01-01

    A new grid optimization scheme is developed for point focus solar cell concentrators which employs a separated grid and busbar concept. Ideally, grid lines act as the primary current collectors and receive all of the current from the semiconductor region. Busbars are the secondary collectors which pick up current from the grids and carry it out of the active region of the solar cell. This separation of functions leads to a multithickness metallization design, where the busbars are made larger in cross section than the grids. This enables the busbars to carry more current per unit area of shading, which is advantageous under high solar concentration where large current densities are generated. Optimized grid patterns using this multilayer concept can provide a 1.6 to 20 percent increase in output power efficiency over optimized single thickness grids.

  8. An optimized top contact design for solar cell concentrators

    Science.gov (United States)

    Desalvo, Gregory C.; Barnett, Allen M.

    1985-01-01

    A new grid optimization scheme is developed for point focus solar cell concentrators which employs a separated grid and busbar concept. Ideally, grid lines act as the primary current collectors and receive all of the current from the semiconductor region. Busbars are the secondary collectors which pick up current from the grids and carry it out of the active region of the solar cell. This separation of functions leads to a multithickness metallization design, where the busbars are made larger in cross section than the grids. This enables the busbars to carry more current per unit area of shading, which is advantageous under high solar concentration where large current densities are generated. Optimized grid patterns using this multilayer concept can provide a 1.6 to 20 percent increase in output power efficiency over optimized single thickness grids.

  9. Screen printed silver top electrode for efficient inverted organic solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Junwoo [Department of Printed Electronics, Korea Institute of Machinery & Materials (KIMM), Daejeon (Korea, Republic of); Duraisamy, Navaneethan [Department of Mechatronics Engineering, Jeju National University, Jeju (Korea, Republic of); Lee, Taik-Min [Department of Printed Electronics, Korea Institute of Machinery & Materials (KIMM), Daejeon (Korea, Republic of); Kim, Inyoung, E-mail: ikim@kimm.re.kr [Department of Printed Electronics, Korea Institute of Machinery & Materials (KIMM), Daejeon (Korea, Republic of); Choi, Kyung-Hyun, E-mail: amm@jejunu.ac.kr [Department of Mechatronics Engineering, Jeju National University, Jeju (Korea, Republic of)

    2015-10-15

    Highlights: • Screen printing of silver pattern. • X-ray diffraction pattern confirmed the face centered cubic structure of silver. • Uniform surface morphology of silver pattern with sheet resistance of 0.06 Ω/sq. • The power conversion efficiency of fabricated solar cell is found to be 2.58%. - Abstract: The present work is mainly focused on replacement of the vacuum process for top electrode fabrication in organic solar cells. Silver top electrode deposited through solution based screen printing on pre-deposited polymeric thin film. The solution based printing technology provides uniform top electrode without damaging the underlying organic layers. The surface crystallinity and surface morphology of silver top electrode are examined through X-ray diffraction, field-emission scanning electron microscope and atomic force microscope. The purity of silver is examined through X-ray energy dispersive spectroscopy. The top electrode exhibits face centered cubic structure with homogeneous morphology. The sheet resistance of top electrode is found to be 0.06 Ω/sq and an average pattern thickness of ∼15 μm. The power conversion efficiency is 2.58%. Our work demonstrates that the solution based screen printing is a significant role in the replacement of vacuum process for the fabrication of top electrode in organic solar cells.

  10. Free-standing terahertz chiral meta-foils exhibiting strong optical activity and negative refractive index

    Science.gov (United States)

    Wu, Jianfeng; Ng, Binghao; Turaga, Shuvan P.; Breese, Mark B. H.; Maier, Stefan A.; Hong, Minghui; Bettiol, Andrew A.; Moser, Herbert O.

    2013-09-01

    A chiral meta-foil consisting of a self-supported square array of interconnected conjugated rosettes is demonstrated at terahertz frequencies. It exhibits strong optical activity and circular dichroism. Negative refractive index with a figure-of-merit as high as 4.2 is achieved, attributed to its free-standing nature. Experimental results are in good agreement with numerical simulation. Free-standing chiral meta-foils provide a unique approach to create a completely all-metal chiral metamaterial, which can be flexibly integrated into optical setups while eliminating dielectric insertion losses.

  11. Free-standing membrane polymer laser on the end of an optical fiber

    Energy Technology Data Exchange (ETDEWEB)

    Zhai, Tianrui, E-mail: trzhai@bjut.edu.cn, E-mail: zhangxinping@bjut.edu.cn; Li, Songtao; Hu, Yujie; Wang, Yimeng; Wang, Li; Zhang, Xinping, E-mail: trzhai@bjut.edu.cn, E-mail: zhangxinping@bjut.edu.cn [Institute of Information Photonics Technology and College of Applied Sciences, Beijing University of Technology, Beijing 100124 (China); Chen, Li [Department of Mathematics and Physics, North China Electric Power University, Hebei 071000 (China)

    2016-01-25

    One- and two-dimensional distributed feedback cavities were constructed on free-standing polymer membranes using spin-coating and lift-off techniques. Low threshold lasing was generated through feedback amplification when the 290-nm membrane device was optically pumped, which was attributed to the strong confinement mechanism provided by the active waveguide layer without a substrate. The free-standing membrane polymer laser is flexible and can be transplanted. Single- and dual-wavelength fiber lasers were achieved by directly attaching the membrane polymer laser on the optical fiber end face. This technique provides potential to fabricate polymer lasers on surfaces with arbitrary shapes.

  12. Quasi free-standing silicene in a superlattice with hexagonal boron nitride

    KAUST Repository

    Kaloni, T. P.

    2013-11-12

    We study a superlattice of silicene and hexagonal boron nitride by first principles calculations and demonstrate that the interaction between the layers of the superlattice is very small. As a consequence, quasi free-standing silicene is realized in this superlattice. In particular, the Dirac cone of silicene is preserved. Due to the wide band gap of hexagonal boron nitride, the superlattice realizes the characteristic physical phenomena of free-standing silicene. In particular, we address by model calculations the combined effect of the intrinsic spin-orbit coupling and an external electric field, which induces a transition from a semimetal to a topological insulator and further to a band insulator.

  13. Liquid droplets on a free-standing glassy membrane: Deformation through the glass transition.

    Science.gov (United States)

    Fortais, Adam; Schulman, Rafael D; Dalnoki-Veress, Kari

    2017-07-01

    In this study, micro-droplets are placed on thin, glassy, free-standing films where the Laplace pressure of the droplet deforms the free-standing film, creating a bulge. The film's tension is modulated by changing temperature continuously from well below the glass transition into the melt state of the film. The contact angle of the liquid droplet with the planar film as well as the angle of the bulge with the film are measured and found to be consistent with the contact angles predicted by a force balance at the contact line.

  14. Energetics of the Phase Transition in Free-Standing versus Supported Lipid Membranes.

    Science.gov (United States)

    Mangiarotti, Agustín; Wilke, Natalia

    2015-07-16

    We compared the thermodynamic behavior of supported and free-standing films of phospholipids with different chain length and showed that the change in free energy for the phase transition to a denser state was greater in free-standing than in supported membranes, with the differences being independent of the chain length. The presence of the support promoted a decrease in the energy gap between the coexisting phases of 1.7 kJ mol(-1), and this was a long-range effect affecting both leaflets, probably related with the impediment of out-of-plane motion of the film by the solid surface.

  15. Restoring a nearly free-standing character of graphene on Ru(0001) by oxygen intercalation.

    Science.gov (United States)

    Voloshina, Elena; Berdunov, Nikolai; Dedkov, Yuriy

    2016-02-08

    Realization of a free-standing graphene is always a demanding task. Here we use scanning probe microscopy and spectroscopy to study the crystallographic structure and electronic properties of the uniform nearly free-standing graphene layers obtained by intercalation of oxygen monolayer in the "strongly" bonded graphene/Ru(0001) interface. Spectroscopic data show that such graphene layer is heavily p-doped with the Dirac point located at 552 meV above the Fermi level. Experimental data are understood within density-functional theory approach and the observed effects are in good agreement with the theoretical data.

  16. Size Effect on Failure of Pre-stretched Free-Standing Nanomembranes

    Directory of Open Access Journals (Sweden)

    Cheng Wenlong

    2010-01-01

    Full Text Available Abstract Free-standing nanomembranes are two-dimensional materials with nanometer thickness but can have macroscopic lateral dimensions. We develop a fracture model to evaluate a pre-stretched free standing circular ultrathin nanomembrane and establish a relation between the energy release rate of a circumferential interface crack and the pre-strain in the membrane. Our results demonstrate that detachment cannot occur when the radius of the membrane is smaller than a critical size. This critical radius is inversely proportional to the Young’s modulus and square of the pre-strain of the membrane.

  17. Free-standing nanomechanical and nanophotonic structures in single-crystal diamond

    Science.gov (United States)

    Burek, Michael John

    Realizing complex three-dimensional structures in a range of material systems is critical to a variety of emerging nanotechnologies. This is particularly true of nanomechanical and nanophotonic systems, both relying on free-standing small-scale components. In the case of nanomechanics, necessary mechanical degrees of freedom require physically isolated structures, such as suspended beams, cantilevers, and membranes. For nanophotonics, elements like waveguides and photonic crystal cavities rely on light confinement provided by total internal reflection or distributed Bragg reflection, both of which require refractive index contrast between the device and surrounding medium (often air). Such suspended nanostructures are typically fabricated in a heterolayer structure, comprising of device (top) and sacrificial (middle) layers supported by a substrate (bottom), using standard surface nanomachining techniques. A selective, isotropic etch is then used to remove the sacrificial layer, resulting in free-standing devices. While high-quality, crystalline, thin film heterolayer structures are readily available for silicon (as silicon-on-insulator (SOI)) or III-V semiconductors (i.e. GaAs/AlGaAs), there remains an extensive list of materials with attractive electro-optic, piezoelectric, quantum optical, and other properties for which high quality single-crystal thin film heterolayer structures are not available. These include complex metal oxides like lithium niobate (LiNbO3), silicon-based compounds such as silicon carbide (SiC), III-V nitrides including gallium nitride (GaN), and inert single-crystals such as diamond. Diamond is especially attractive for a variety of nanoscale technologies due to its exceptional physical and chemical properties, including high mechanical hardness, stiffness, and thermal conductivity. Optically, it is transparent over a wide wavelength range (from 220 nm to the far infrared), has a high refractive index (n ~ 2.4), and is host to a vast

  18. Are embedded validity indices equivalent to free-standing symptom validity tests?

    Science.gov (United States)

    Miele, Andrea S; Gunner, Jessica H; Lynch, Julie K; McCaffrey, Robert J

    2012-01-01

    Symptom validity assessment is an important part of neuropsychological evaluation. There are currently several free-standing symptom validity tests (SVTs), as well as a number of empirically derived embedded validity indices, that have been developed to assess that an examinee is putting forth an optimal level of effort during testing. The use of embedded validity indices is attractive since they do not increase overall testing time and may also be less vulnerable to coaching. In addition, there are some instances where embedded validity indices are the only tool available to the neuropsychological practitioner for assessing an examinee's level of effort. As with free-standing measures, the sensitivity and specificity of embedded validity indices to suboptimal effort varies. The present study evaluated the diagnostic validity of 17 embedded validity indices by comparing performance on these indices to performance on combinations of free-standing SVTs. Results from the current medico-legal sample revealed that of the embedded validity indices, Reliable Digit Span had the best classification accuracy; however, the findings do not support the use of this embedded validity index in the absence of free-standing SVTs.

  19. Fabrication of free-standing replicas of fragile, laminar, chitinous biotemplates.

    Science.gov (United States)

    Lakhtakia, Akhlesh; Martín-Palma, Raúl J; Motyka, Michael A; Pantano, Carlo G

    2009-09-01

    The conformal-evaporated-film-by-rotation technique, followed by the dissolution of chitin in an aqueous solution of orthophosphoric acid, can be used to fabricate free-standing replicas of fragile, laminar, chitinous biotemplates. This novel approach was demonstrated using butterfly wings as biotemplates and GeSeSb chalcogenide glass for replicas.

  20. Highly conductive free standing polypyrrole films prepared by freezing interfacial polymerization.

    Science.gov (United States)

    Qi, Guijin; Huang, Liyan; Wang, Huiliang

    2012-08-25

    Highly conductive free standing polypyrrole (PPy) films were prepared by a novel freezing interfacial polymerization method. The films exhibit metallic luster and electrical conductivity up to 2000 S cm(-1). By characterizing with SEM, FTIR, Raman and XRD, the high conductivity is attributed to the smooth surface, higher conjugation length and more ordered molecular structure of PPy.

  1. Numerical Simulation of Luminescent Downshifting in Top Cell of Monolithic Tandem Solar Cells

    Directory of Open Access Journals (Sweden)

    Mahfoud Abderrezek

    2013-01-01

    Full Text Available The increase in the conversion efficiency of monolithic tandem solar cells is limited by the short-circuit current density matching between the top and the bottom cells. Generally, the top cell presents the lowest current in the two subcells. In this paper, in order to increase the short-circuit current density in the top cell, we present a theoretical survey of the luminescence downshifting (LDS approach for the design of monolithic tandem solar cells. The photovoltaic (PV glass encapsulation material is replaced with a polymer material of polymethyl methacrylate (PMMA type which is doped with diverse kinds of organic dyes. The performance of the n-p-p+ GaInP structure has been simulated as a function of the organic dyes. Gains achieved for the short-circuit current density and conversion efficiency are, respectively, 13.13% and 13.38%, under AM1.5G illumination spectra.

  2. Integration of Solar Cells on Top of CMOS Chips - Part II: CIGS Solar Cells

    NARCIS (Netherlands)

    Lu, J.; Liu, Wei; Kovalgin, Alexeij Y.; Sun, Yun; Schmitz, Jurriaan

    2011-01-01

    We present the monolithic integration of deepsubmicrometer complementary metal–oxide–semiconductor (CMOS) microchips with copper indium gallium (di)selenide (CIGS) solar cells. Solar cells are manufactured directly on unpackaged CMOS chips. The microchips maintain comparable electronic performance,

  3. Integration of Solar Cells on Top of CMOS Chips - Part II: CIGS Solar Cells

    NARCIS (Netherlands)

    Lu, Jiwu; Liu, Wei; Kovalgin, Alexey Y.; Sun, Yun; Schmitz, Jurriaan

    2011-01-01

    We present the monolithic integration of deepsubmicrometer complementary metal–oxide–semiconductor (CMOS) microchips with copper indium gallium (di)selenide (CIGS) solar cells. Solar cells are manufactured directly on unpackaged CMOS chips. The microchips maintain comparable electronic performance,

  4. Integration of Solar Cells on Top of CMOS Chips Part I: a-Si Solar Cells

    NARCIS (Netherlands)

    Lu, J.; Kovalgin, Alexeij Y.; van der Werf, Karine H.M.; Schropp, Ruud E.I.; Schmitz, Jurriaan

    2011-01-01

    We present the monolithic integration of deepsubmicrometer complementary metal–oxide–semiconductor (CMOS) microchips with a-Si:H solar cells. Solar cells are manufactured directly on the CMOS chips. The microchips maintain comparable electronic performance, and the solar cells show efficiency values

  5. Integration of Solar Cells on Top of CMOS Chips Part I: a-Si Solar Cells

    NARCIS (Netherlands)

    Lu, Jiwu; Kovalgin, Alexey Y.; Werf, van der Karine H.M.; Schropp, Ruud E.I.; Schmitz, Jurriaan

    2011-01-01

    We present the monolithic integration of deepsubmicrometer complementary metal–oxide–semiconductor (CMOS) microchips with a-Si:H solar cells. Solar cells are manufactured directly on the CMOS chips. The microchips maintain comparable electronic performance, and the solar cells show efficiency values

  6. Low temperature processed planar heterojunction perovskite solar cells employing silver nanowires as top electrode

    Science.gov (United States)

    Zhang, Jianhua; Li, Fushan; Yang, Kaiyu; Veeramalai, Chandrasekar Perumal; Guo, Tailiang

    2016-04-01

    In this paper, we reported a low temperature processed planar heterojunction perovskite solar cell employing silver nanowires as the top electrode and ZnO nanoparticles as the electron transport layer. The CH3NH3PbI3 perovskite was grown as the light absorber via two-step spin-coating technique. The as-fabricated perovskite solar cell exhibited the highest power conversion efficiency of 9.21% with short circuit current density of 19.75 mA cm-2, open circuit voltage of 1.02, and fill factor value of 0.457. The solar cell's performance showed negligible difference between the forward and reverse bias scan. This work paves a way for realizing low cost solution processable solar cells.

  7. Growth of Free-standing Diamond Films on Graphite Substrates with Ti Interlayers

    Institute of Scientific and Technical Information of China (English)

    LI Hui-qing; LI Cheng-ming; CHEN Guang-chao; LU Fan-xiu; TANG Wei-zhong; TONG Yu-mei

    2004-01-01

    Free-standing diamond films, deposited using Dc Arc Plasma Jet CVD method onto graphite substrates with titanium interlayers, have been investigated. The Ti interlayers were deposited by arc ion plating equipments. The thickness,morphology and composite phase of Ti interlayers were examined by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The titanium carbide (TiC) was detected in both sides of the interlayers, which played an important role with respect to reasonable adhesion with film and diamond nucleation. The semi-translucent diamond films were characterized by SEM and Raman spectrum. The sharp diamond peak with low intensity of amorphous carbon shows that diamond films have very high quality. The overall results suggest that plating Ti interlayer on graphite substrate is an effective way to obtain optical grade free-standing diamond films.

  8. Growth of Free-standing Diamond Films on Graphite Substrates with Ti Interlayers

    Institute of Scientific and Technical Information of China (English)

    LIHui-qing; LICheng-ming; CHENGuang-chao; LUFan-xiu; TANGWei-zhong; TONGYu-mei

    2004-01-01

    Free-standing diamond films, deposited using De Arc Plasma Jet CVD method onto graphite substrates with titanium interlayers, have been investigated. The Ti interlayers were deposited by arc ion plating equipments. The thickness, morphology and composite phase of Ti interlayers were examined by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The titanium carbide (TIC) was detected in both sides of the interlayers, which played an important role with respect to reasonable adhesion with film and diamond nucleation. The semi-translucent diamond films were characterized by SEM and Raman spectrum. The sharp diamond peak with low intensity of amorphous carbon shows that diamond films have very high quality. The overall results suggest that plating Ti interlayer on graphite substrate is an effective way to obtain optical grade free-standing diamond films.

  9. Robust Alginate-Catechol@Polydopamine Free-Standing Membranes Obtained from the Water/Air Interface.

    Science.gov (United States)

    Ponzio, Florian; Le Houerou, Vincent; Zafeiratos, Spyridon; Gauthier, Christian; Garnier, Tony; Jierry, Loic; Ball, Vincent

    2017-03-07

    The formation of polydopamine composite membranes at the water/air interface using different chemical strategies is reported. The use of either small molecules (urea, pyrocatechol) or polymers paves the way to understand which kind of compounds can be used for the formation of PDA-composite free-standing membranes produced at the water/air interface. On the basis of these screening results, we have found that alginate grafted with catechol groups allows the formation of robust free-standing films with asymmetric composition, stimuli-responsiveness, and self-healing properties. The stickiness of these membranes depends on the relative humidity, and its adhesion behavior on PDMS was characterized using the JKR method. Thus, alginate-catechol polydopamine films appear as a new class of PDA composites, mechanically robust through covalent cross-linking and based on fully biocompatible constituting partners. These results open the door to potential applications in the biomedical field.

  10. Inverse-Ordered Fabrication of Free-Standing CNT Sheets for Supercapacitor.

    Science.gov (United States)

    Koo, Youngmi; Shanov, Vesselin N; Yarmolenko, Sergey; Schulz, Mark; Sankar, Jagannathan; Yun, Yeoheung

    2015-07-14

    Free-standing thin carbon nanotube (CNT) sheets are challenging to handle and control for device fabrication. In this paper, we report on the inverse-ordered fabrication method from thick CNT sheets to thin free-standing CNT sheets. As proof of the concept, thin CNT sheets for a supercapacitor were fabricated from 200 thick layers. The results show that the thin CNT sheet was electrochemically stable and had enhanced capacitive performance. The smaller the number of layers is, the larger the specific capacitances we have (from 10.10 F g(-1) to 51.37 F g(-1)). Energy and power density were increased from 0.50 to 2.57 Wh kg(-1) and from 0.33 to 2.31 kW kg(-1), respectively. This simple and scalable inverse-ordered method is capable to fabricate CNT sheets in various forms, allowing fast trials on various applications.

  11. Free-Standing GaMnAs Nanomachined Sheets for van der Pauw Magnetotransport Measurements

    Directory of Open Access Journals (Sweden)

    Jae-Hyun Lee

    2016-12-01

    Full Text Available We report on the realization of free-standing GaMnAs epilayer sheets using nanomachining techniques. By optimizing the growth conditions of the sacrificial Al0.75Ga0.25As layer, free-standing metallic GaMnAs (with ~6% Mn microsheets (with TC ~85 K with integrated electrical probes are realized for magnetotransport measurements in the van der Pauw geometry. GaMnAs epilayer needs to be physically isolated to avoid buckling effects stemming from the release of lattice mismatch strain during the removal of the AlGaAs sacrificial layer. From finite element analysis, symmetrically placed and serpentine-shaped electrical leads induce minimal thermal stress at low temperatures. From magnetotransport measurements, changes in magnetic anisotropy are readily observed.

  12. Improved electrical properties of free standing blend polymer for renewable energy resources

    Science.gov (United States)

    Arya, Anil; Sharma, Sweety; Sharma, A. L.

    2016-05-01

    Blend polymer electrolytes are prepared for salt concentration (Ö/Li = 4) with the constant ratio (0.5 gm) of PEO and PAN using solution casting technique. The prepared free standing solid polymeric film is characterized by Field Emission Scanning Electron Microscopy (FESEM) which confirms the homogeneous distribution of dissociated salt in blend polymer matrix. After addition of salt the ionic conductivity value is found to be of the order of 7.13 × 10-5 Scm-1 which is three orders higher when compared with pure blend polymer films. The microscopic interaction among the polymer-ion, ion-ion has been confirmed by the Fourier Transform Infrared (FTIR) Spectroscopy. A very fine correlation has been built in the electrical conductivity and FTIR result. On the basis of above finding, a prepared free standing solid polymeric film appears to be appropriate for the energy storage/conversion device applications.

  13. Deformation of Thin Free-standing Films with Sessile Droplets Through the Glass Transition

    Science.gov (United States)

    Fortais, Adam; Schulman, Rafael; Dalnoki-Veress, Kari

    Droplets on a rigid substrate will form a contact angle determined by interfacial tensions according to Young's law. Likewise, the Laplace pressure of a droplet will deform a liquid substrate, and the contact line geometry can be determined through a Neumann construction. We explore the intermediate case of micro-droplets placed on thin, highly compliant, free-standing films. The Laplace pressure of the droplet deforms the free-standing film, creating a spherical bulge. The film's tension is modulated by changing temperature continuously from well below the glass transition into the melt state of the film. The contact angle of the liquid droplet with the undeformed film as well as the angle of the bulge with the film is measured and compared to the contact angles predicted by a force balance at the contact line.

  14. Optical Soliton Propagation in a Free-Standing Nonlinear Graphene Monolayer with Defects

    CERN Document Server

    Moxley, Frederick Ira; Radadia, Adarsh; Dai, Weizhong

    2013-01-01

    Recently, optical soliton propagation in an intrinsic nonlinear graphene monolayer configuration has been discovered. However, optical soliton behavior in a free-standing graphene monolayer with defects has not yet been studied. The objective of this article is to employ the generalized finite- difference time-domain (G-FDTD) method to efficiently simulate bright optical solitons, illustrating propagation of the electric field distribution in a free-standing nonlinear layer with variation in nonlinearity along its width. These variations of nonlinearity along the width represent graphene impurities, or defects. Results show that solitons propagate effectively even in the presence of strong spatial variations in the nonlinearity, implying the robustness of the medium with respect to optical propagation.

  15. Flexible, cathodoluminescent and free standing mesoporous silica films with entrapped quasi-2D perovskites

    Science.gov (United States)

    Vassilakopoulou, Anastasia; Papadatos, Dionysios; Koutselas, Ioannis

    2017-04-01

    The effective entrapment of hybrid organic-inorganic semiconductors (HOIS) into mesoporous polymer-silica hybrid matrices, formed as free standing flexible films, is presented for the first time. A blend of quasi-2D HOIS, simply synthesized by mixing two-dimensional (2D) and three dimensional (3D) HOIS, exhibiting strong photoluminescence, is embedded into porous silica matrices during the sol-gel synthesis, using tetraethylorthosilicate as precursor and Pluronic F-127 triblock copolymer as structure directing agent, under acidic conditions. The final nanostructure hybrid forms flexible, free standing films, presenting high cathodoluminescence and long stable excitonic luminescence, indicating the protective character of the hybrid matrix towards the entrapped perovskite. A significant result is that the photoluminescence of the entrapped HOIS is not affected even after films' prolonged exposure to water.

  16. Free-standing high quality factor thin-film lithium niobate micro-photonic disk resonators

    CERN Document Server

    Wang, Renyuan

    2014-01-01

    Lithium Niobate (LN or just niobate) thin-film micro-photonic resonators have promising prospects in many applications including high efficiency electro-optic modulators, optomechanics and nonlinear optics. This paper presents free-standing thin-film lithium niobate photonic resonators on a silicon platform using MEMS fabrication technology. We fabricated a 35um radius niobate disk resonator that exhibits high intrinsic optical quality factor (Q) of 484,000. Exploiting the optomechanical interaction from the released free-standing structure and high optical Q, we were able to demonstrate acousto-optic modulation from these devices by exciting a 56MHz radial breathing mechanical mode (mechanical Q of 2700) using a probe.

  17. Infiltrated Porous Polymer Sheets as Free-Standing Flexible Lithium-Sulfur Battery Electrodes.

    Science.gov (United States)

    Wu, Feixiang; Zhao, Enbo; Gordon, Daniel; Xiao, Yiran; Hu, Chenchen; Yushin, Gleb

    2016-08-01

    Free-standing, high-capacity Li2 S electrodes with capacity loadings in the range from 1.5 to 3.8 mA h cm(-2) are produced by using infiltration of active materials into porous carbonized biomass sheets. The proposed electrode design can be effectively utilized for the low-cost fabrication of flexible lithium batteries with high specific energy.

  18. Diamond free-standing porous membranes; Membranas porosas auto-sustentadas de diamante

    Energy Technology Data Exchange (ETDEWEB)

    Mammana, Victor Pellegrini

    1996-07-01

    A method for fabricating free-standing diamond membranes with controlled porous density and size, using silicon molds is presented. This method has advantages compared to those developed until now, specially concerning to its simplicity and membrane characteristics. The process is described step by step, and a morphological study of the porous is done, in order to identify the relevance of each step, in the membrane characteristics. Finally, a proposal is made to improve the process in the future. (author)

  19. A laboratory experiment for a new free-standing pupil mask coronagraph

    Science.gov (United States)

    Haze, K.; Enya, K.; Kotani, T.; Abe, L.; Nakagawa, T.; Matsuhara, H.; Sato, T.; Yamamuro, T.

    2012-09-01

    This paper presents the results of a laboratory experiment on a new free-standing pupil mask coronagraph for the direct observation of exoplanets. We focused on a binary-shaped pupil coronagraph, which is planned for installation in the next-generation infrared space telescope SPICA. Our laboratory experiments on the coronagraph were implemented inside a vacuum chamber (HOCT) to achieve greater thermal stability and to avoid air turbulence, and a contrast of 1.3×10-9 was achieved with PSF subtraction. We also carried out multi-color/broadband experiments to demonstrate that the pupil mask coronagraph works, in principle, at all wavelengths. We had previously manufactured a checker-board mask, a type of binary-shaped pupil mask, on a glass substrate, which had the disadvantages of light loss by transmission, ghosting from residual reflectance and a slightly different refractive index for each wavelength. Therefore, we developed a new free-standing mask in sheet metal, for which no substrate was needed. As a result of a He-Ne laser experiment with the free-standing mask, a contrast of 1.0×10-7 was achieved for the raw coronagraphic image. We also conducted rotated mask subtractions and numerical simulations of some errors in the mask shape and WFEs. Speckles are the major limiting factor. The free-standing mask exhibited about the same ability to improve contrast as the substrate mask. Consequently, the results of this study suggest that the binary-shaped pupil mask coronagraph can be applied to coronagraphic observations by SPICA and other telescopes.

  20. Free-Standing Nanomechanical and Nanophotonic Structures in Single-Crystal Diamond

    OpenAIRE

    Burek, Michael John

    2016-01-01

    Realizing complex three-dimensional structures in a range of material systems is critical to a variety of emerging nanotechnologies. This is particularly true of nanomechanical and nanophotonic systems, both relying on free-standing small-scale components. In the case of nanomechanics, necessary mechanical degrees of freedom require physically isolated structures, such as suspended beams, cantilevers, and membranes. For nanophotonics, elements like waveguides and photonic crystal cavities rel...

  1. Fabrication and microwave shielding properties of free standing polyaniline-carbon fiber thin sheets

    Energy Technology Data Exchange (ETDEWEB)

    Joon, Seema [Polymeric & Soft Material Section, CSIR-National Physical Laboratory, New Delhi 110012 (India); Department of Physics, DCRUST Murthal, Sonepat, Haryana 130001 (India); PDM College of Engineering, Bahadurgarh, Haryana 124507 (India); Kumar, Rakesh [Polymeric & Soft Material Section, CSIR-National Physical Laboratory, New Delhi 110012 (India); PDM College of Engineering, Bahadurgarh, Haryana 124507 (India); Singh, Avanish Pratap [Polymeric & Soft Material Section, CSIR-National Physical Laboratory, New Delhi 110012 (India); Shukla, Rajni [Department of Physics, DCRUST Murthal, Sonepat, Haryana 130001 (India); Dhawan, S.K., E-mail: skdhawan@mail.nplindia.ernet.in [Polymeric & Soft Material Section, CSIR-National Physical Laboratory, New Delhi 110012 (India)

    2015-06-15

    Attempt has been made to synthesize polyaniline-carbon fiber (PANI-CF) composite via in-situ emulsion polymerization using β-naphthalene sulphonic acid (NSA) which acts as both surfactant as well as dopant. Free standing PANI-CF thin sheets are prepared which have electrical conductivity ∼1.02 S/cm with improved mechanical strength and thermal stability. The scanning electron microscopy is used to study the surface morphology of the composites. Structural characterization is done by using XRD. The dielectric attributes (ε* = ε′ − iε″) of PANI-CF sheets are calculated using experimental S parameters (S{sub 11}, S{sub 12}) by Nicolson Ross Wier equations. It has been demonstrated that these sheets show maximum shielding effectiveness (SE) of 31.9 dB at 12.4 GHz frequency at a thickness of 1.5 mm. Free standing PANI-CF sheets so prepared have a potential for X-band microwave absorber application. - Highlights: • Free standing polyaniline-carbon fiber thin sheets fabricated for EMI shielding. • The mechanical strength of sheets improves with phenolic resin loading. • The dielectric parameters were calculated by Nicholson Ross Wier equations. • Sheets (1.5 mm thickness) demonstrate SE of 31.9 dB at 12.4 GHz frequency. • Sheets find potential application for X-band microwave absorption.

  2. Boundary condition and pre-strain effects on the free standing indentation response of graphene monolayer.

    Science.gov (United States)

    Zhou, Lixin; Wang, Yugang; Cao, Guoxin

    2013-11-27

    Using molecular mechanics simulations, we investigated the true pre-stress/pre-strain state of graphene in free standing indentation and the effect of the pre-strain (ε0) on the free standing indentation response of graphene is also considered. We found that there is essentially no effective pre-tension in graphene during free standing indentation and the reported pre-tensile stress determined from the indentation tests does not show the true pre-stress state of graphene, which is a 'fake stress' caused by the assumption (the indenter tip displacement is equal to the displacement of graphene) typically used in the classic indentation analysis. A negative ε0 will increase the van der Waals (VDW) interaction between the indenter tip and graphene to cause a larger overestimation of both values of the elastic modulus (E) and the nonlinear elastic constant (c) of graphene from the classic indentation analysis. However, applying a positive ε0 in graphene, the VDW effect will be significantly decreased, and a more accurate value of E can be obtained, but the value of c will decrease to zero, which may become an effective way to more accurately obtain the elastic stiffness of graphene from indentation tests.

  3. Thermal stability and spontaneous breakdown of free-standing metal nanowires

    Science.gov (United States)

    Michailov, Michail; Ranguelov, Bogdan; Giazitzidis, Paraskevas; Argyrakis, Panos

    2017-01-01

    We present a model for vacancy-mediated spontaneous breakdown of free-standing monatomic nanowire based on exclusively random, thermally activated motion of atoms. The model suggests a new two-step vacancy-mediated mechanism for nanowire rupture compared to the more complex three-step hole-mediated mechanism driving the disintegration of nanowire on crystalline surface. It also demonstrates that a free-standing nanowire breaks down much more rapidly than a nanowire on a substrate, because it cannot experience the stabilizing effect of the nanowire/substrate interactions. The rupture mechanism includes single atomic vacancy generation, preceded by appearance of weakly bonded active atoms. The analysis of the simulation data indicates that the active atoms act as a precursor of vacancy formation. These two successive events in the temporal evolution of the nanowire morphology bring the free-standing nanowire into irreversible unstable state, leading to its total disintegration. The present study also manifests an unexpected substantial increase of the nanowire lifetime with diminishing the strength of the atomic interactions between the nanowire atoms. The simulation data reveal three energy regions where a large oscillatory variation of nanowire lifetime is realized. The first region of strong atomic interactions is characterized by tight nanowire rigidity and short lifetime. The next, second region in the consecutive step-down of the attractive interatomic force is characterized by generation of wave-shaped morphology of the atomic chain, enhanced flexibility and dramatic increase of nanowire lifetime. In the last, third region, further weakening of the interactions returns the nanowire again to unstable, short-lifetime state. The observed phenomenon is considered as a "stick-like" to "polymer-like" transition in the nanowire atomic structure as a result of interaction energy variation. The enhanced flexibility reduces the nanowire free energy since it favors and

  4. Low temperature processed planar heterojunction perovskite solar cells employing silver nanowires as top electrode

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Jianhua; Li, Fushan, E-mail: fushanli@hotmail.com; Yang, Kaiyu; Veeramalai, Chandrasekar Perumal; Guo, Tailiang

    2016-04-30

    Graphical abstract: - Highlights: • All solution processed perovskite solar cells were realized with Ag nanowires. • ZnO nanoparticles were used as electron transport layer. • The solar cells showed a photovoltaic behavior with efficiency of 9.21%. • Device performance showed negligible difference between forward and reverse scan. - Abstract: In this paper, we reported a low temperature processed planar heterojunction perovskite solar cell employing silver nanowires as the top electrode and ZnO nanoparticles as the electron transport layer. The CH{sub 3}NH{sub 3}PbI{sub 3} perovskite was grown as the light absorber via two-step spin-coating technique. The as-fabricated perovskite solar cell exhibited the highest power conversion efficiency of 9.21% with short circuit current density of 19.75 mA cm{sup −2}, open circuit voltage of 1.02, and fill factor value of 0.457. The solar cell's performance showed negligible difference between the forward and reverse bias scan. This work paves a way for realizing low cost solution processable solar cells.

  5. Table-top solar flares produced with laser driven magnetic reconnections

    Directory of Open Access Journals (Sweden)

    Zhong J.Y.

    2013-11-01

    Full Text Available The American Nuclear Society (ANS has presented the prestigious Edward Teller award to Dr. Bruce A. Remington during the 2011 IFSA conference due to his “pioneering scientific work in the fields of inertial confinement fusion (ICF, and especially developing an international effort in high energy density laboratory astrophysics” [1,2]. This is a great acknowledgement to the subject of high energy density laboratory astrophysics. In this context, we report here one experiment conducted to model solar flares in the laboratory with intense lasers [3]. The mega-gauss –scale magnetic fields produced by laser produced plasmas can be used to make magnetic reconnection topology. We have produced one table-top solar flare in our laboratory experiment with the same geometric setup as associated with solar flares.

  6. Above-the-loop-top Oscillation and Quasi-periodic Coronal Wave Generation in Solar Flares

    CERN Document Server

    Takasao, Shinsuke

    2016-01-01

    Observations revealed that various kinds of oscillations are excited in solar flare regions. Quasi-periodic pulsations (QPPs) in the flare emissions are commonly observed in a wide range of wavelengths. Recent observations have found that fast-mode magnetohydrodynamic (MHD) waves are quasi-periodically emitted from some flaring sites (quasi-periodic propagating fast-mode magnetoacoustic waves; QPFs). Both of QPPs and QPFs imply a cyclic disturbance originating from the flaring sites. However, the physical mechanisms remain puzzling. By performing a set of two-dimensional MHD simulations of a solar flare, we discovered the local oscillation above the loops filled with evaporated plasma (above-the-loop-top region) and the generation of QPFs from such oscillating regions. Unlike all previous models for QPFs, our model includes essential physics for solar flares, such as magnetic reconnection, heat conduction, and chromospheric evaporation. We revealed that QPFs can be spontaneously excited by the above-the-loop-...

  7. Above-the-loop-top Oscillation and Quasi-periodic Coronal Wave Generation in Solar Flares

    Science.gov (United States)

    Takasao, Shinsuke; Shibata, Kazunari

    2016-06-01

    Observations revealed that various kinds of oscillations are excited in solar flare regions. Quasi-periodic pulsations (QPPs) in flare emissions are commonly observed in a wide range of wavelengths. Recent observations have found that fast-mode magnetohydrodynamic (MHD) waves are quasi-periodically emitted from some flaring sites (quasi-periodic propagating fast-mode magnetoacoustic waves; QPFs). Both QPPs and QPFs imply a cyclic disturbance originating from the flaring sites. However, the physical mechanisms remain puzzling. By performing a set of two-dimensional MHD simulations of a solar flare, we discovered the local oscillation above the loops filled with evaporated plasma (above-the-loop-top region) and the generation of QPFs from such oscillating regions. Unlike all previous models for QPFs, our model includes essential physics for solar flares such as magnetic reconnection, heat conduction, and chromospheric evaporation. We revealed that QPFs can be spontaneously excited by the above-the-loop-top oscillation. We found that this oscillation is controlled by the backflow of the reconnection outflow. The new model revealed that flare loops and the above-the-loop-top region are full of shocks and waves, which is different from the previous expectations based on a standard flare model and previous simulations. In this paper, we show the QPF generation process based on our new picture of flare loops and will briefly discuss a possible relationship between QPFs and QPPs. Our findings will change the current view of solar flares to a new view in which they are a very dynamic phenomenon full of shocks and waves.

  8. Free-standing optoelectronic graphene-CdS-graphene oxide composite paper produced by vacuum-assisted self-assembly

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yong-Feng [Chinese Academy of Sciences, Key Laboratory of Carbon Materials, Institute of Coal Chemistry, Taiyuan (China); Graduate University of Chinese Academy of Sciences, Beijing (China); Liu, Yan-Zhen; Shen, Wen-Zhong; Yang, Yong-Gang; Wang, Mao-Zhang [Chinese Academy of Sciences, Key Laboratory of Carbon Materials, Institute of Coal Chemistry, Taiyuan (China); Wen, Yue-Fang [Zhejiang University, Department of Chemical and Biological Engineering, Hangzhou (China)

    2012-03-15

    Free-standing optoelectronic graphene-CdS-graphene oxide (G-CdS-GO) composite papers were prepared by vacuum-assisted self-assembly. G-CdS hybrids were first prepared by a hydrothermal method and GO acts as a dispersant which makes it easier to disperse them to form relatively stable aqueous suspensions for fabricating paper. Transmission electron microscopy shows that CdS quantum dots (QDs) with an average size of approximately 1-2 nm were distributed uniformly on the graphene sheets. Photoluminescence measurements for the as-prepared G-CdS-GO composite paper showed that the surface defect related emissions of attached CdS QDs decrease and blue shift obviously due to the change in particle size and the interaction of the surface of the CdS QDs with both the GO and the graphene sheets. The resulting paper holds great potential for applications in thin film solar cells, sensors, diodes, and so on. (orig.)

  9. Solar Energetic Particle Spectrum on 13 December 2006 Determined by IceTop

    Energy Technology Data Exchange (ETDEWEB)

    IceCube Collaboration; Klein, Spencer

    2008-10-11

    The IceTop air shower array now under construction at the South Pole as the surface component of the IceCube neutrino telescope (Achterberg et al. 2006) detected an unusual near-solar-minimum Ground Level Enhancement (GLE) after a solar flare on 13 December 2006. Beginning at 0220 UT, the 4B class flare occurred at solar coordinates S06 W24, accompanied by strong (X3.4) X-ray emission and type II and IV radio bursts. The LASCO coronagraph on the SOHO spacecraft observed a halo CME launch from the Sun at {approx} 0225 UT with speed estimated to be {approx} 1770 km/s. We have begun (Bieber et al. 2007) a comprehensive analysis of the propagation of solar energetic particles in this event. However the focus of this Letter is the new and unique ability of IceTop to derive the energy spectrum of these particles in the multi-GeV regime from a single detector with a well defined viewing direction. When completed, IceTop will have approximately 500 square meters of ice Cherenkov collecting area arranged in an array of 80 stations on a 125 m triangular grid to detect air showers from one PeV to one EeV. Each station consists of two, two meter diameter tanks filled with ice to a depth of 90 cm. Tanks are instrumented with two Digital Optical Modules (DOM) operated at different gain settings to provide appropriate dynamic range to cover both large and small air showers. Each DOM contains a 10 inch photomultiplier and an advanced readout system capable of digitizing the full waveform. For historical reasons, the two discriminator counting rates recorded in each DOM are termed SPE (Single Photo Electron), and MPE (Multi Photo Electron). In the present analysis the SPE threshold corresponds approximately to 20 photoelectrons (PE), and the MPE threshold to 100 PE. Due to the high altitude (2835m) and the nearly zero geomagnetic cutoff at the South Pole, secondary particle spectra at the detector retain a significant amount of information on the spectra of the primary particles

  10. Efficient Colorful Perovskite Solar Cells Using a Top Polymer Electrode Simultaneously as Spectrally Selective Antireflection Coating.

    Science.gov (United States)

    Jiang, Youyu; Luo, Bangwu; Jiang, Fangyuan; Jiang, Fuben; Fuentes-Hernandez, Canek; Liu, Tiefeng; Mao, Lin; Xiong, Sixing; Li, Zaifang; Wang, Tao; Kippelen, Bernard; Zhou, Yinhua

    2016-12-14

    Organometal halide perovskites have shown excellent optoelectronic properties and have been used to demonstrate a variety of semiconductor devices. Colorful solar cells are desirable for photovoltaic integration in buildings and other aesthetically appealing applications. However, the realization of colorful perovskite solar cells is challenging because of their broad and large absorption coefficient that commonly leads to cells with dark-brown colors. Herein, for the first time, we report a simple and efficient strategy to achieve colorful perovskite solar cells by using the transparent conducting polymer (poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate), PEDOT:PSS) as a top electrode and simultaneously as an spectrally selective antireflection coating. Vivid colors across the visible spectrum are attained by engineering optical interference effects among the transparent PEDOT:PSS polymer electrode, the hole-transporting layer and the perovskite layer. The colored perovskite solar cells display power conversion efficiency values from 12.8 to 15.1% (from red to blue) when illuminated from the FTO glass side and from 11.6 to 13.8% (from red to blue) when illuminated from the PEDOT:PSS side. The new approach provides an advanced solution for fabricating colorful perovskite solar cells with easy processing and high efficiency.

  11. Unresolved Fine-scale Structure in Solar Coronal Loop-tops

    Science.gov (United States)

    Scullion, E.; Rouppe van der Voort, L.; Wedemeyer, S.; Antolin, P.

    2014-12-01

    New and advanced space-based observing facilities continue to lower the resolution limit and detect solar coronal loops in greater detail. We continue to discover even finer substructures within coronal loop cross-sections, in order to understand the nature of the solar corona. Here, we push this lower limit further to search for the finest coronal loop substructures, through taking advantage of the resolving power of the Swedish 1 m Solar Telescope/CRisp Imaging Spectro-Polarimeter (CRISP), together with co-observations from the Solar Dynamics Observatory/Atmospheric Image Assembly (AIA). High-resolution imaging of the chromospheric Hα 656.28 nm spectral line core and wings can, under certain circumstances, allow one to deduce the topology of the local magnetic environment of the solar atmosphere where its observed. Here, we study post-flare coronal loops, which become filled with evaporated chromosphere that rapidly condenses into chromospheric clumps of plasma (detectable in Hα) known as a coronal rain, to investigate their fine-scale structure. We identify, through analysis of three data sets, large-scale catastrophic cooling in coronal loop-tops and the existence of multi-thermal, multi-stranded substructures. Many cool strands even extend fully intact from loop-top to footpoint. We discover that coronal loop fine-scale strands can appear bunched with as many as eight parallel strands within an AIA coronal loop cross-section. The strand number density versus cross-sectional width distribution, as detected by CRISP within AIA-defined coronal loops, most likely peaks at well below 100 km, and currently, 69% of the substructure strands are statistically unresolved in AIA coronal loops.

  12. Corrosion Behavior of Cold Sprayed Titanium Coatings and Free Standing Deposits

    Science.gov (United States)

    Hussain, T.; McCartney, D. G.; Shipway, P. H.; Marrocco, T.

    2011-01-01

    Cold gas dynamic spraying can be used to deposit oxygen-sensitive materials, such as titanium, without significant chemical degradation of the powder. The process is thus believed to have potential for the deposition of corrosion-resistant barrier coatings. However, to be effective, a barrier coating must not allow ingress of a corrosive liquid and hence must not have interconnected porosity. This study investigated the effects of porosity on the corrosion behavior of cold sprayed titanium coatings onto carbon steel and also of free standing deposits. For comparative purposes, a set of free standing deposits was also vacuum heat-treated to further decrease porosity levels below those in the as-sprayed condition. Microstructures were examined by optical and scanning electron microscopy. Mercury intrusion porosimetry (MIP) was used to characterize the interconnected porosity over a size range of micrometers to nanometers. Open circuit potential (OCP) measurements and potentiodynamic polarization scans in 3.5 wt.% NaCl were used to evaluate the corrosion performance. The MIP results showed that in cold sprayed deposits a significant proportion of the porosity was sub-micron and so could not be reliably measured by optical microscope based image analysis. In the case of free standing deposits, a reduction in interconnected porosity resulted in a lower corrosion current density, a lower passive current density, and an increase in OCP closer to that of bulk titanium. For the lowest porosity level, ~1.8% achieved following vacuum heat treatment, the passive current density was identical to that of bulk titanium. However, electrochemical measurements of the coatings showed significant substrate influence when the interconnected porosity of the coating was 11.3 vol.% but a decreased substrate influence with a porosity level of 5.9 vol.%. In the latter case, the OCP was still around 250 mV below that of bulk Ti. Salt spray tests confirmed these electrochemical findings and

  13. Flexible Free-Standing III-Nitride Thin Films for Emitters and Displays.

    Science.gov (United States)

    Cheung, Y F; Li, K H; Choi, H W

    2016-08-24

    The majority of a GaN light-emitting diode (LED) is released from its sapphire substrate through selective-area laser lift-off to form a freely suspended light emitter. By virtue of being suspended in air without supporting substrates, the ultrathin crystalline and crack-free film possesses flexibility and bendability. The free-standing LEDs benefit from significant relaxation of strain, evident from red-shifting of the E2(high) phonon frequencies as measured by Raman spectroscopy toward those of strain-free free-standing GaN substrates. The phonon frequencies remain invariant upon bending of the film; this indicates that the properties of the flexible device will not be dependent on the bending curvatures. The observation of pronounced spectral blue-shifts from the photoluminescence (PL) spectrum from the flexible regions further confirms the occurrence of strain relaxation in the quantum wells. Being free-standing and thus lacking a direct heat-sinking pathway, emissions from the different regions of the suspended film can be affected by thermal effects to different extents, which are investigated by long-wave infrared thermometry. Heat accumulation is determined to be most severe at the far end of the flexible stripe at higher currents, leading to reduced efficiencies and electroluminescence (EL) spectral red-shifts. Based on this architecture, a monolithic 3 × 4 dot-matrix microdisplay prototype is demonstrated, comprising three adjacent flexible stripe emitters with four individually addressable pixels on each stripe. This proof-of-concept demonstration opens up new opportunities for GaN optoelectronics for a wide range of flexible display and visual applications.

  14. Molecular beam epitaxy of free-standing wurtzite AlxGa1-xN layers

    Science.gov (United States)

    Novikov, S. V.; Staddon, C. R.; Martin, R. W.; Kent, A. J.; Foxon, C. T.

    2015-09-01

    Recent developments with group III nitrides present AlxGa1-xN based LEDs as realistic devices for new alternative deep ultra-violet light sources. Because there is a significant difference in the lattice parameters of GaN and AlN, AlxGa1-xN substrates would be preferable to either GaN or AlN for ultraviolet device applications. We have studied the growth of free-standing wurtzite AlxGa1-xN bulk crystals by plasma-assisted molecular beam epitaxy (PA-MBE). Thick wurtzite AlxGa1-xN films were grown by PA-MBE on 2-in. GaAs (111)B substrates and were removed from the GaAs substrate after growth to provide free standing AlxGa1-xN samples. X-ray microanalysis measurements confirm that the AlN fraction is uniform across the wafer and mass spectroscopy measurements show that the composition is also uniform in depth. We have demonstrated that free-standing wurtzite AlxGa1-xN wafers can be achieved by PA-MBE for a wide range of AlN fractions. In order to develop a commercially viable process for the growth of wurtzite AlxGa1-xN substrates, we have used a novel Riber plasma source and have demonstrated growth rates of GaN up to 1.8 μm/h on 2-in. diameter GaAs and sapphire wafers.

  15. Facile synthesis of oxidation-resistant copper nanowires toward solution-processable, flexible, foldable, and free-standing electrodes.

    Science.gov (United States)

    Yin, Zhenxing; Lee, Chaedong; Cho, Sanghun; Yoo, Jeeyoung; Piao, Yuanzhe; Kim, Youn Sang

    2014-12-29

    Oxidation-resistant copper nanowires (Cu NWs) are synthesized by a polyol reduction method. These Cu NWs show excellent oxidation resistance, good dispersibility, and have a low sintering temperature. A Cu NW-based flexible, foldable, and free-standing electrode is fabricated by filtration and a sintering process. The electrode also exhibits high electrical conductivity even bending, folding, and free-standing. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Carbon nanohorns-coated microfibers for use as free-standing electrodes for electrochemical power sources

    Energy Technology Data Exchange (ETDEWEB)

    Aissa, Brahim; Hamoudi, Zehira; Mohamedi, Mohamed; Khakani, My Ali El [Institut National de Recherche Scientifique, Energie, Materiaux et Telecommunications, 1650 Blvd. Lionel Boulet, Varennes, Quebec (Canada); Takahashi, Hiro; Tohji, Kazuyuki [Department of Environmental Studies, Graduate School of Environmental Studies, Tohoku University, Aza-aoba 6-6-11, Aramaki, Aoba-ku, Sendai 9808579 (Japan)

    2009-04-15

    We report the first direct laser based synthesis of carbon nanohorns onto carbon microfibrous, for the straightforward fabrication, of free-standing (binderless) electrodes. These carbon nanohorns have diameters as small as 2-4 nm and were found to cover uniformly the microfibrous substrates. The carbon nanohorns-based electrodes developed here are shown to open new prospects for the development of advanced electrochemical power sources. In particular, their possible applications in either lithium-ion batteries or supercapacitors or fuel cell technologies are demonstrated. (author)

  17. Field Emission from an Array of Free-standing Metallic Nanowires

    Institute of Scientific and Technical Information of China (English)

    张耿民; Emmanuel ROY; 刘虹雯; 刘惟敏; 侯士敏; Kui YU-ZHANG; 薛增泉

    2002-01-01

    Arrays of single crystalline gold nanowires were synthesized electrochemically in porous polycarbonate mem-branes. The polycarbonate membrane was then removed to obtain free-standing nanowires for field emissionmeasurements. The turn-on electric field strength for field emission is found to be lower than 2V/μm. The actualelectric field that extracted electrons out of the gold nanowires is estimated to be about 1 03 times higher than thefield directly expected in the model of a parallel plate condenser. The availability of the field emission is thereforeattributed to the strong electric field at the tips resulting from smallcurvature radius of the gold nanowires.

  18. Free-standing biomimetic polymer membrane imaged with atomic force microscopy

    DEFF Research Database (Denmark)

    Rein, Christian; Pszon-Bartosz, Kamila Justyna; Jensen, Karin Bagger Stibius

    2011-01-01

    Fluid polymeric biomimetic membranes are probed with atomic force microscopy (AFM) using probes with both normal tetrahedrally shaped tips and nanoneedle-shaped Ag2Ga rods. When using nanoneedle probes, the collected force volume data show three distinct membrane regions which match the expected...... membrane structure when spanning an aperture in a hydrophobic scaffold. The method used provides a general method for mapping attractive fluid surfaces. In particular, the nanoneedle probing allows for characterization of free-standing biomimetic membranes with thickness on the nanometer scale suspended...

  19. Free-Standing Bimetallic Nanorings and Nanoring Arrays Made by On-Wire Lithography

    Energy Technology Data Exchange (ETDEWEB)

    Liusman, C.; Li, S. Z.; Chen, X. D.; Wei, W.; Zhang, H.; Schatz, George C.; Boey, F.; Mirkin, Chad

    2010-12-28

    This paper describes a new strategy for synthesizing free-standing bimetallic nanorings and nanoring arrays based upon on-wire lithography and a galvanic replacement reaction. The strategy allows one to tune the diameter, length, and therefore aspect ratio of the nanorings. In addition, it can be used to produce arrays of nanorings in high yield with control over number and spacing. Spectroscopic studies and discrete dipole approximation calculations show that nanoring dimers exhibit greater surface enhanced Raman scattering than the analogous nanodisk dimers.

  20. In Situ Characterization of the Local Work Function along Individual Free Standing Nanowire by Electrostatic Deflection.

    Science.gov (United States)

    Chen, Yicong; Zhao, Chengchun; Huang, Feng; Zhan, Runze; Deng, Shaozhi; Xu, Ningsheng; Chen, Jun

    2016-02-17

    In situ characterization of the work function of quasi one dimensional nanomaterials is essential for exploring their applications. Here we proposed to use the electrostatic deflection induced by work function difference between nanoprobe and nanowire for in situ measuring the local work function along a free standing nanowire. The physical mechanism for the measurement was discussed in details and a parabolic relationship between the deflection and the potential difference was derived. As a demonstration, measurement of the local work functions on the tip and the sidewall of a ZnO nanowire with Au catalyst at its end and a LaB6 nanowire have been achieved with good accuracy.

  1. Creation and characterization of free-standing cryogenic targets for laser-driven ion acceleration

    Science.gov (United States)

    Tebartz, Alexandra; Bedacht, Stefan; Hesse, Markus; Astbury, Sam; Clarke, Rob; Ortner, Alex; Schaumann, Gabriel; Wagner, Florian; Neely, David; Roth, Markus

    2017-09-01

    A technique for the creation of free-standing cryogenic targets for laser-driven ion acceleration is presented, which allows us to create solid state targets consisting of initially gaseous materials. In particular, the use of deuterium and the methods for its preparation as a target material for laser-driven ion acceleration are discussed. Moving in the phase diagram through the liquid phase leads to the substance covering an aperture on a cooled copper frame where it is solidified through further cooling. An account of characterization techniques for target thickness is given, with a focus on deducing thickness values from distance values delivered by chromatic confocal sensors.

  2. Anisotropic high-field terahertz response of free-standing carbon nanotubes

    Science.gov (United States)

    Lee, Byounghwak; Mousavian, Ali; Paul, Michael J.; Thompson, Zachary J.; Stickel, Andrew D.; McCuen, Dalton R.; Jang, Eui Yun; Kim, Yong Hyup; Kyoung, Jisoo; Kim, Dai-Sik; Lee, Yun-Shik

    2016-06-01

    We demonstrate that unidirectionally aligned, free-standing multi-walled carbon nanotubes (CNTs) exhibit highly anisotropic linear and nonlinear terahertz (THz) responses. For the polarization parallel to the CNT axis, strong THz pulses induce nonlinear absorption in the quasi-one-dimensional conducting media, while no nonlinear effect is observed in the perpendicular polarization configuration. Time-resolved measurements of transmitted THz pulses and a theoretical analysis of the data reveal that intense THz fields enhance permittivity in carbon nanotubes by generating charge carriers.

  3. Silver Nanowire Top Electrodes in Flexible Perovskite Solar Cells using Titanium Metal as Substrate.

    Science.gov (United States)

    Lee, Minoh; Ko, Yohan; Min, Byoung Koun; Jun, Yongseok

    2016-01-08

    Flexible perovskite solar cells (FPSCs) have various applications such as wearable electronic textiles and portable devices. In this work, we demonstrate FPSCs on a titanium metal substrate employing solution-processed silver nanowires (Ag NWs) as the top electrode. The Ag NW electrodes were deposited on top of the spiro-MeOTAD hole transport layer by a carefully controlled spray-coating method at moderate temperatures. The power conversion efficiency (PCE) reached 7.45 % under AM 1.5 100 mW cm(-2) illumination. Moreover, the efficiency for titanium-based FPSCs decreased only slightly (by 2.6 % of the initial value) after the devices were bent 100 times. With this and other advances, fully solution-based indium-free flexible photovoltaics, advantageous in terms of price and processing, have the potential to be scaled into commercial production. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Highly efficient ultrathin-film amorphous silicon solar cells on top of imprinted periodic nanodot arrays

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Wensheng, E-mail: yws118@gmail.com; Gu, Min, E-mail: mgu@swin.edu.au [Centre for Micro-Photonics, Faculty of Science, Engineering and Technology, Swinburne University of Technology, Hawthorn, Victoria 3122 (Australia); Tao, Zhikuo [College of Electronic Science and Engineering, Nanjing University of Posts and Telecommunications, Nanjing 210023 (China); Ong, Thiam Min Brian [Plasma Sources and Application Center, NIE, Nanyang Technological University, 1 Nanyang Walk, Singapore 637616 (Singapore); Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology and Research), 3 Research Link, Singapore 117602 (Singapore)

    2015-03-02

    The addressing of the light absorption and conversion efficiency is critical to the ultrathin-film hydrogenated amorphous silicon (a-Si:H) solar cells. We systematically investigate ultrathin a-Si:H solar cells with a 100 nm absorber on top of imprinted hexagonal nanodot arrays. Experimental evidences are demonstrated for not only notable silver nanodot arrays but also lower-cost ITO and Al:ZnO nanodot arrays. The measured external quantum efficiency is explained by the simulation results. The J{sub sc} values are 12.1, 13.0, and 14.3 mA/cm{sup 2} and efficiencies are 6.6%, 7.5%, and 8.3% for ITO, Al:ZnO, and silver nanodot arrays, respectively. Simulated optical absorption distribution shows high light trapping within amorphous silicon layer.

  5. A transparent, solvent-free laminated top electrode for perovskite solar cells.

    Science.gov (United States)

    Makha, Mohammed; Fernandes, Silvia Letícia; Jenatsch, Sandra; Offermans, Ton; Schleuniger, Jürg; Tisserant, Jean-Nicolas; Véron, Anna C; Hany, Roland

    2016-01-01

    A simple lamination process of the top electrode for perovskite solar cells is demonstrated. The laminate electrode consists of a transparent and conductive plastic/metal mesh substrate, coated with an adhesive mixture of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate), PEDOT:PSS, and sorbitol. The laminate electrode showed a high degree of transparency of 85%. Best cell performance was achieved for laminate electrodes prepared with a sorbitol concentration of ~30 wt% per milliliter PEDOT:PSS dispersion, and using a pre-annealing temperature of 120°C for 10 min before lamination. Thereby, perovskite solar cells with stabilized power conversion efficiencies of (7.6 ± 1.0)% were obtained which corresponds to 80% of the reference devices with reflective opaque gold electrodes.

  6. Preparation of free-standing diamond films for high frequency SAW devices

    Institute of Scientific and Technical Information of China (English)

    LIU Jian-min; XIA Yi-ben; WANG Lin-jun; SU Qing-feng; ZHAO Ping; XU Run; PENG Hong-yan; SHI Wei-min

    2006-01-01

    Free-standing diamond films were prepared by hot filament chemical vapor deposition (HFCVD) method under different conditions. Inter-digital transducers (IDTs) were formed on the nucleation sides of free-standing diamond films by photolithography technique. Then piezoelectric ZnO films were deposited by radio-frequency(RF) reactive magnetron sputtering to obtain the ZnO/diamond film structures. Surface morphologies of the nucleation sides and the IDTs were characterized by means of scanning electron microscopy (SEM),atomic force microscope (AFM) and optical microscopy. The results indicate that the surfaces of nucleation sides are very smooth and the IDTs are of high quality without discontinuity and short circuit phenomenon. Raman spectra show the sharp diamond feature peak at about 1 334 cm-1 and the small amount of non-diamond carbon in the nucleation side. X-ray diffraction (XRD) patterns of the structure of ZnO/diamond films show a strong diffraction peak of ZnO (002),which indicates that as-sputtered ZnO films are highly c-axis oriented.

  7. A Large, Free-Standing Wire Grid for Microwave Variable-delay Polarization Modulation

    Science.gov (United States)

    Voellmer, George

    2008-01-01

    One technique for mapping the polarization signature of the cosmic microwave background uses large, polarizing grids in reflection. We present the system requirements, the fabrication, assembly, and alignment procedures, and the test results for the polarizing grid component of a 50 cm clear aperture, Variable-delay Polarization Modulator (VPM). This grid is being built and tested at the Goddard Space Flight Center as part of the Polarimeter for Observing Inflationary Cosmology at the Reionization Epoch (POINCARE). VPMs modulate the polarized component of a radiation source by splitting the incoming beam into two orthogonal polarization components using a free-standing wire grid. The path length difference between these components is varied with a translating mirror, and then they are recombined. This precision instrumentation technique can be used to encode and demodulate the cosmic microwave background's polarization signature. For the demonstration instrument, 64 micrometer diameter tungsten wires are being assembled into a 200 pm pitch, free-standing wire grid with a 50 cm clear aperture, and an expected overall flatness better than 30 micrometers. A rectangular, aluminum stretching frame holds the wires with sufficient tension to achieve a minimum resonant frequency of 185 Hz, allowing VPM mirror translation frequencies of several Hz. A lightly loaded, flattening ring with a 50 cm inside diameter rests against the wires and brings them into accurate planarity.

  8. Oxygen Absorption in Free-Standing Porous Silicon: A Structural, Optical and Kinetic Analysis

    Directory of Open Access Journals (Sweden)

    Cisneros Rodolfo

    2010-01-01

    Full Text Available Abstract Porous silicon (PSi is a nanostructured material possessing a huge surface area per unit volume. In consequence, the adsorption and diffusion of oxygen in PSi are particularly important phenomena and frequently cause significant changes in its properties. In this paper, we study the thermal oxidation of p+-type free-standing PSi fabricated by anodic electrochemical etching. These free-standing samples were characterized by nitrogen adsorption, thermogravimetry, atomic force microscopy and powder X-ray diffraction. The results show a structural phase transition from crystalline silicon to a combination of cristobalite and quartz, passing through amorphous silicon and amorphous silicon-oxide structures, when the thermal oxidation temperature increases from 400 to 900 °C. Moreover, we observe some evidence of a sinterization at 400 °C and an optimal oxygen-absorption temperature about 700 °C. Finally, the UV/Visible spectrophotometry reveals a red and a blue shift of the optical transmittance spectra for samples with oxidation temperatures lower and higher than 700 °C, respectively.

  9. Mechanical Behavior of Free-Standing Fuel Cell Electrodes on Water Surface.

    Science.gov (United States)

    Kim, Sanwi; Kim, Jae-Han; Oh, Jong-Gil; Jang, Kyung-Lim; Jeong, Byeong-Heon; Hong, Bo Ki; Kim, Taek-Soo

    2016-06-22

    Fundamental understanding of the mechanical behavior of polymer electrolyte fuel cell electrodes as free-standing materials is essential to develop mechanically robust fuel cells. However, this has been a significant challenge due to critical difficulties, such as separating the pristine electrode from the substrate without damage and precisely measuring the mechanical properties of the very fragile and thin electrodes. We report the mechanical behavior of free-standing fuel cell electrodes on the water surface through adopting an innovative ice-assisted separation method to separate the electrode from decal transfer film. It is found that doubling the ionomer content in electrodes increases not only the tensile stress at the break and the Young's modulus (E) of the electrodes by approximately 2.1-3.5 and 1.7-2.4 times, respectively, but also the elongation at the break by approximately 1.5-1.7 times, which indicates that stronger, stiffer, and tougher electrodes are attained with increasing ionomer content, which have been of significant interest in materials research fields. The scaling law relationship between Young's modulus and density (ρ) has been unveiled as E ∼ ρ(1.6), and it is compared with other materials. These findings can be used to develop mechanically robust electrodes for fuel cell applications.

  10. Free-standing and flexible graphene papers as disposable non-enzymatic electrochemical sensors.

    Science.gov (United States)

    Zhang, Minwei; Halder, Arnab; Hou, Chengyi; Ulstrup, Jens; Chi, Qijin

    2016-06-01

    We have explored AuNPs (13 nm) both as a catalyst and as a core for synthesizing water-dispersible and highly stable core-shell structural gold@Prussian blue (Au@PB) nanoparticles (NPs). Systematic characterization by transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) disclosed AuNPs coated uniformly by a 5 nm thick PB layer. Au@PB NPs were attached to single-layer graphene oxide (GO) to form Au@PB decorated GO sheets. The resulting hybrid material was filtered layer-by-layer into flexible and free-standing GO paper, which was further converted into conductive reduced GO (RGO)/Au@PB paper via hydrazine vapour reduction. High-resolution TEM images suggested that RGO papers are multiply sandwich-like structures functionalized with core-shell NPs. Resulting sandwich functionalized graphene papers have high conductivity, sufficient flexibility, and robust mechanical strength, which can be cut into free-standing electrodes. Such electrodes, used as non-enzymatic electrochemical sensors, were tested systematically for electrocatalytic sensing of hydrogen peroxide. The high performance was indicated by some of the key parameters, for example the linear H2O2 concentration response range (1-30 μM), the detection limit (100 nM), and the high amperometric sensitivity (5 A cm(-2) M(-1)). With the advantages of low cost and scalable production capacity, such graphene supported functional papers are of particular interest in the use as flexible disposable sensors.

  11. Thermoelectric Performances of Free-Standing Polythiophene and Poly(3-Methylthiophene) Nanofilms

    Science.gov (United States)

    Lu, Bao-Yang; Liu, Cong-Cong; Lu, Shan; Xu, Jing-Kun; Jiang, Feng-Xing; Li, Yu-Zhen; Zhang, Zhuo

    2010-05-01

    Thermoelectric performances of free-standing polythiophene (PT) and poly(3-methylthiophene) (PMeT) nanofilms with high tensile strength electrosynthesized from boron trifluoride diethyl etherate (BFEE) are systematically investigated. They display decent electric conductivity (47 and 73 S · cm-1), high Seebeck coefficient (130 and 76 μ V · K-1) and low thermal conductivity (0.17 and 0.15 W · m-1 · K-1) at room temperature. Their figure of merit can reach 3.0 × 10-2 at 250K, higher than that of many other conducting polymers. The decrease of charge carrier concentration resulting from volatile and water-sensitive dopants from BFEE leads to the decrease of electrical conductivity but a substantial increase of the Seebeck coefficient, making their figure-of-merit values maintained at more than 10-2 even after prolonged storage (two months). Moreover, free-standing PT and PMeT exhibit much better thermoelectric performances than those in pressed pellets due to the good arrangement of the polymer chains and preferably oriented structure in films. It therefore provides a way to improve the thermoelectric performances of conducting polymers by controlling regularity of the extended conjugated chain structure and/or the chain packing to achieve high charge mobility.

  12. 80-MHz intravascular ultrasound transducer using PMN-PT free-standing film.

    Science.gov (United States)

    Li, Xiang; Wu, Wei; Chung, Youngsoo; Shih, Wan Y; Shih, Wei-Heng; Zhou, Qifa; Shung, K Kirk

    2011-11-01

    [Pb(Mg(1/3)Nb(2/3))O(3)](0.63)[PbTiO(3)](0.37) (PMN-PT) free-standing film of comparable piezoelectric properties to bulk material with thickness of 30 μm has been fabricated using a modified precursor coating approach. At 1 kHz, the dielectric permittivity and loss were 4364 and 0.033, respectively. The remnant polarization and coercive field were 28 μC/cm(2) and 18.43 kV/cm. The electromechanical coupling coefficient k(t) was measured to be 0.55, which was close to that of bulk PMN-PT single-crystal material. Based on this film, high-frequency (82 MHz) miniature ultrasonic transducers were fabricated with 65% bandwidth and 23 dB insertion loss. Axial and lateral resolutions were determined to be as high as 35 and 176 μm. In vitro intravascular imaging on healthy rabbit aorta was performed using the thin film transducers. In comparison with a 35-MHz IVUS transducer, the 80-MHz transducer showed superior resolution and contrast with satisfactory penetration depth. The imaging results suggest that PMN-PT free-standing thin film technology is a feasible and efficient way to fabricate very-high-frequency ultrasonic transducers.

  13. Graphene and hydroxyapatite self-assemble into homogeneous, free standing nanocomposite hydrogels for bone tissue engineering.

    Science.gov (United States)

    Xie, Xingyi; Hu, Kaiwen; Fang, Dongdong; Shang, Lihong; Tran, Simon D; Cerruti, Marta

    2015-05-07

    Graphene-nanoparticle (NP) composites have shown potential in applications ranging from batteries to, more recently, tissue engineering. Graphene and NPs should be integrated into uniform free-standing structures for best results. However, to date, this has been achieved only in few examples; in most cases, graphene/NP powders lacking three-dimensional (3D) structure were produced. Here we report a facile and universal method that can be used to synthesize such structures based on colloidal chemistry. We start from aqueous suspensions of both graphene oxide nanosheets and citrate-stabilized hydroxyapatite (HA) NPs. Hydrothermal treatment of the mixtures of both suspensions reduces graphene oxide to graphene, and entraps colloidal HA NPs into the 3D graphene network thanks to a self-assembled graphite-like shell formed around it. Dialysis through this shell causes uniform NP deposition onto the graphene walls. The resulting graphene-HA gels are highly porous, strong, electrically conductive and biocompatible, making them promising scaffolds for bone tissue engineering. This method can be applied to produce a variety of free-standing 3D graphene-based nanocomposites with unprecedented homogeneity.

  14. Free-Standing Organic Transistors and Circuits with Sub-Micron Thicknesses

    Science.gov (United States)

    Fukuda, Kenjiro; Sekine, Tomohito; Shiwaku, Rei; Morimoto, Takuya; Kumaki, Daisuke; Tokito, Shizuo

    2016-06-01

    The realization of wearable electronic devices with extremely thin and flexible form factors has been a major technological challenge. While substrates typically limit the thickness of thin-film electronic devices, they are usually necessary for their fabrication and functionality. Here we report on ultra-thin organic transistors and integrated circuits using device components whose substrates that have been removed. The fabricated organic circuits with total device thicknesses down to 350 nm have electrical performance levels close to those fabricated on conventional flexible substrates. Moreover, they exhibit excellent mechanical robustness, whereby their static and dynamic electrical characteristics do not change even under 50% compressive strain. Tests using systematically applied compressive strains reveal that these free-standing organic transistors possess anisotropic mechanical stability, and a strain model for a multilayer stack can be used to describe the strain in this sort of ultra-thin device. These results show the feasibility of ultimate-thin organic electronic devices using free-standing constructions.

  15. Constructing Free Standing Metal Organic Framework MIL-53 Membrane Based on Anodized Aluminum Oxide Precursor

    Science.gov (United States)

    Zhang, Yunlu; Gao, Qiuming; Lin, Zhi; Zhang, Tao; Xu, Jiandong; Tan, Yanli; Tian, Weiqian; Jiang, Lei

    2014-05-01

    Metal organic framework (MOF) materials have attracted great attention due to their well-ordered and controllable pores possessing of prominent potentials for gas molecule sorption and separation performances. Organizing the MOF crystals to a continuous membrane with a certain scale will better exhibit their prominent potentials. Reports in recent years concentrate on well grown MOF membranes on specific substrates. Free standing MOF membranes could have more important applications since they are independent from the substrates. However, the method to prepare such a membrane has been a great challenge because good mechanical properties and stabilities are highly required. Here, we demonstrate a novel and facile technique for preparing the free standing membrane with a size as large as centimeter scale. The substrate we use proved itself not only a good skeleton but also an excellent precursor to fulfill the reaction. This kind of membrane owns a strong mechanical strength, based on the fact that it is much thinner than the composite membranes grown on substrates and it could exhibit good property of gas separation.

  16. Thermally Induced Shape Modification of Free-standing Nanostructures for Advanced Functionalities

    Science.gov (United States)

    Cui, Ajuan; Li, Wuxia; Shen, Tiehan H.; Yao, Yuan; Fenton, J. C.; Peng, Yong; Liu, Zhe; Zhang, Junwei; Gu, Changzhi

    2013-08-01

    Shape manipulation of nanowires is highly desirable in the construction of nanostructures, in producing free-standing interconnect bridges and as a building block of more complex functional structures. By introducing asymmetry in growth parameters, which may result in compositional or microstructural non-uniformity in the nanowires, thermal annealing can be used to induce shape modification of free-standing nanowires. We demonstrate that such manipulation is readily achieved using vertically grown Pt-Ga-C composite nanowires fabricated by focused-ion-beam induced chemical vapor deposition. Even and controllable bending of the nanowires has been observed after a rapid thermal annealing in a N2 atmosphere. The mechanisms of the shape modification have been examined. This approach has been used to form electrical contacts to freestanding nano-objects as well as nano-`cages' for the purpose of securing ZnO tubs. These results suggest that thermally induced bending of nanowires may have potential applications in constructing three-dimensional nanodevices or complex structures for the immobilization of particles and large molecules.

  17. Recycling of p-type mc-si Top Cuts into p-type mono c-Si Solar Cells

    Energy Technology Data Exchange (ETDEWEB)

    Bronsveld, P.C.P.; Manshanden, P.; Lenzmann, F.O. [ECN Solar Energy, Westerduinweg 3, P.O. Box 1, NL-1755 ZG Petten (Netherlands); Gjerstad, O. [Si Pro Holding AS, Ornesveien 3, P.O. Box 37, 8161, Glomfjord (Norway); Oevrelid, E.J. [SINTEF, Alfred Getz Vei 2, 7465, Trondheim (Norway)

    2013-07-01

    Solar cell results and material analysis are presented of 2 p-type Czochralski (Cz) ingots pulled from a charge consisting of 100% and 50% recycled multicrystalline silicon top cuts. The top cuts were pre-cleaned with a dedicated low energy consuming technology. No structure loss was observed in the bodies of the ingots. The performance of solar cells made from the 100% recycled Si ingot decreases towards the seed end of the ingot, which could be related to a non-optimal pulling process. Solar cells from the tail end of this ingot and from the 50% recycled Si ingot demonstrated an average solar cell efficiency of 18.6%. This is only 0.1% absolute lower than the efficiency of higher resistivity reference solar cells from commercially available wafers that were co-processed.

  18. Substitutional carbon doping of free-standing and Ru-supported BN sheets: a first-principles study

    Science.gov (United States)

    Berseneva, N.; Komsa, H.-P.; Vierimaa, V.; Björkman, T.; Fan, Z.; Harju, A.; Todorović, M.; Krasheninnikov, A. V.; Nieminen, R. M.

    2017-10-01

    The development of spatially homogeneous mixed structures with boron (B), nitrogen (N) and carbon (C) atoms arranged in a honeycomb lattice is highly desirable, as they open the possibility of creating stable two-dimensional materials with tunable band gaps. However, at least in the free-standing form, the mixed BCN system is energetically driven towards phase segregation to graphene and hexagonal BN. It is possible to overcome the segregation when BCN material is grown on a particular metal substrate, for example Ru(0 0 0 1), but the stabilization mechanism is still unknown. With the use of density-functional theory we study the energetics of BN/Ru slabs, with different types of configurations of C substitutional defects introduced to the h-BN overlayer. The results are compared to the energetics of free-standing BCN materials. We found that the substrate facilitates the C substitution process in the h-BN overlayer. Thus, more homogeneous BCN material can be grown, overcoming the segregation into graphene and h-BN. In addition, we investigate the electronic and transport gaps in free-standing BCN structures, and assess their mechanical properties and stability. The band gap in mixed BCN free-standing material depends on the concentration of the constituent elements and ranges from zero in pristine graphene to nearly 5 eV in free-standing h-BN. This makes BCN attractive for application in modern electronics.

  19. Electro-chemo-mechanical response of a free-standing polypyrrole strip

    Energy Technology Data Exchange (ETDEWEB)

    Vazquez, G; Otero, T F; Cascales, J J L [Centra de ElectroquImica y Materiales Inteligentes (CEMI), Universidad Politecnica de Cartagena, Cartagena 30203, Murcia (Spain)], E-mail: javier.lopez@upct.es

    2008-08-15

    Further development of mechanical devices based on conducting polymers; require a precise understanding of their mechanical response, i.e. their control, under a controlled external current. In this work, we show some results for the relation between the electrical current consumed in the electrochemical process and the mechanical work developed by a freestanding polypyrrole strip, when it is subjected to a stretching force (stress). Under these conditions, from the results obtained in this work, we observe how it results almost impossible to predict a straight relationship between mechanical work and current consumed in the electrochemical process. In addition, we will quantify the variation of the mechanical properties of the free standing polypyrrole strip associated with the oxidation state of the polymer by measuring its Young's modulus.

  20. Nanoscale electromechanical and electronic properties of free-standing ZnO nano- and microstructured platelets

    Science.gov (United States)

    Faraji, N.; Adelung, R.; Mishra, Y. K.; Seidel, J.

    2017-10-01

    The piezoelectric response, conductivity and surface potential of individual grains and grain boundaries in free-standing polycrystalline ZnO nano- and microstructured platelets is studied using scanning probe based techniques on the nanoscale. We find that applied dc electric fields can alter the piezoresponse in individual grains, as well as the local nanoscale conductivity, and invert the relative surface potential at grain boundaries. This can be attributed to defect accumulation at the grain surfaces and at grain boundaries and the associated density of carriers. Together with recently observed below-bandgap photoconductivity at grain boundaries, the presented observation opens new venues for potential nanoelectronic applications that rely on grain and grain boundary engineering and functionality in a wide-bandgap transparent material.

  1. Free-standing alumina nanobottles and nanotubes pre-integrated into nanoporous alumina membranes

    Science.gov (United States)

    Fang, Jinghua; Levchenko, Igor; (Ken Ostrikov, Kostya

    2014-08-01

    A novel interfacial structure consisting of long (up to 5 μm), thin (about 300 nm), highly-ordered, free-standing, highly-reproducible aluminum oxide nanobottles and long tubular nanocapsules attached to a rigid, thin (less than 1 μm) nanoporous anodic alumina membrane is fabricated by simple, fast, catalyst-free, environmentally friendly voltage-pulse anodization. A growth mechanism is proposed based on the formation of straight channels in alumina membrane by anodization, followed by neck formation due to a sophisticated voltage control during the process. This process can be used for the fabrication of alumina nanocontainers with highly controllable geometrical size and volume, vitally important for various applications such as material and energy storage, targeted drug and diagnostic agent delivery, controlled drug and active agent release, gene and biomolecule reservoirs, micro-biologically protected platforms, nano-bioreactors, tissue engineering and hydrogen storage.

  2. Converse Piezoelectric Effect Induced Transverse Deflection of a Free-Standing ZnO Microbelt

    KAUST Repository

    Hu, Youfan

    2009-07-08

    We demonstrate the first electric field induced transverse deflection of a single-crystal, free-standing ZnO microbelt as a result of converse piezoelectric effect. For a microbelt growing along the c-axis, a shear stress in the a-c plane can be induced when an electric field E is applied along the a-axis of the wurtzite structure. As amplified by the large aspect ratio of the microbelt that grows along the c-axis, the strain localized near the root can be detected via the transverse deflection perpendicular to the ZnO microbelt. After an experimental approach was carefully designed and possible artifacts were ruled out, the experimentally observed degree of deflection of the microbelt agrees well with the theoretically expected result. The device demonstrated has potential applications as transverse actuators/sensors/switches and electric field induced mechanical deflectors. © 2009 American Chemical Society.

  3. Electronic structure and magnetism of samarium and neodymium adatoms on free-standing graphene

    Science.gov (United States)

    Kozub, Agnieszka L.; Shick, Alexander B.; Máca, František; Kolorenč, Jindřich; Lichtenstein, Alexander I.

    2016-09-01

    The electronic structure of selected rare-earth atoms adsorbed on a free-standing graphene was investigated using methods beyond the conventional density functional theory (DFT+U , DFT+HIA, and DFT+ED). The influence of the electron correlations and the spin-orbit coupling on the magnetic properties has been examined. The DFT+U method predicts both atoms to carry local magnetic moments (spin and orbital) contrary to a nonmagnetic f6 (J =0 ) ground-state configuration of Sm in the gas phase. Application of DFT +Hubbard-I (HIA) and DFT +exact diagonalization (ED) methods cures this problem, and yields a nonmagnetic ground state with six f electrons and J =0 for the Sm adatom. Our calculations show that Nd adatom remains magnetic, with four localized f electrons and J =4.0 . These conclusions could be verified by STM and XAS experiments.

  4. Free-Standing Porous Carbon Nanofiber Networks from Electrospinning Polyimide for Supercapacitors

    Directory of Open Access Journals (Sweden)

    Bo Wang

    2016-01-01

    Full Text Available Free-standing porous carbon nanofiber networks (CFNs were synthesized by electrospinning method and carbonization procedure. We study the implementation of porous CFNs as supercapacitor electrodes and electrochemical measurements demonstrated that porous CFNs exhibit a specific capacitance (205 F/g at the scan rate of 5 mV/s with high flexibility and good rate capability performance (more than 70% of its initial capacitance from 5 mV/s to 200 mV/s. Furthermore, porous CFNs exhibited an excellent cycling stability (just 12% capacitance loss after 10,000 cycles. These results suggest that porous CFNs are very promising candidates as flexible supercapacitor electrodes.

  5. Free-standing carbon nanotube/graphene hybrid papers as next generation adsorbents.

    Science.gov (United States)

    Dichiara, Anthony B; Sherwood, Tyler J; Benton-Smith, Jared; Wilson, Jonathan C; Weinstein, Steven J; Rogers, Reginald E

    2014-06-21

    The adsorption of a series of aromatic compounds from aqueous solution onto purified, free-standing single-walled carbon nanotube/graphene nanoplatelet hybrid papers is studied both experimentally and theoretically. Experimental data is obtained via changes in optical absorption spectra of the aqueous solutions and is used to extract all parameters required to implement a semi-empirical mass-transfer model. Agreement between experiment and theory is excellent and data from all compounds can be cast on a universal adsorption curve. Results indicate that the rate of adsorption and long-time capacity of many aromatic compounds on hybrid paper adsorbent significantly exceeds that of activated carbon by at least an order of magnitude. The combination of carbon nanotubes and graphene also promotes on the order of a 25% improvement in adsorption rates and capacities than either component alone. Hybrid nanocomposites show significant promise as adsorption materials used for environmental remediation efforts.

  6. Theoretical Studies of Oxygen Reactivity of Free-Standing and Supported Boron-Doped Graphene.

    Science.gov (United States)

    Di Valentin, Cristiana; Ferrighi, Lara; Fazio, Gianluca

    2016-05-23

    Graphene inertness towards chemical reactivity can be considered as an accepted postulate by the research community. This limit has been recently overcome by chemically and physically modifying graphene through non-metal doping or interfacing with acceptor/donor materials (metals or semiconductors). As a result, outstanding performances as catalytic, electrocatalytic, and photocatalytic material have been observed. In this critical Review we report computational work performed, by our group, on the reactivity of free-standing, metal- and semiconductor-supported B-doped graphene towards oxygen, which is at the basis of extremely important energy-related chemical processes, such as the oxygen reduction reaction. It appears that a combination of doping and interfacing approaches for the activation of graphene can open unconventional and unprecedented reaction paths, thus boosting the potential of modified graphene in many chemical applications. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. A phase-field study of the scaling law in free-standing ferroelectric thin films.

    Science.gov (United States)

    Yin, Binglun; Mao, Huina; Qu, Shaoxing

    2015-12-18

    The scaling law for ferroelectric stripe domains is investigated in free-standing BaTiO3 and PbTiO3 thin films via phase-field simulations. The results agree with the Kittel law, where the square of the domain width is found to be proportional to the thin film thickness. After being rescaled by the corresponding domain wall thickness, the generalized scaling law is also demonstrated, with the dimensionless scaling constant M estimated to be ∼3.3 in two ferroelectric materials. Moreover, we predict the effect of the exchange constant which is incorporated in Ginzburg-Landau theory on the equilibrium domain width and the critical thickness of the ferroelectric thin films.

  8. Free-standing cancer centers: rationale for improving cancer care delivery.

    Science.gov (United States)

    Lokich, J J; Silvers, S; Brereton, H; Byfield, J; Bick, R

    1989-10-01

    Free-standing cancer centers (FSCC) represent a growing trend in cancer care delivery within community practice. The critical components to FSCC are multidisciplinary cancer care, a complete menu of direct care and support services, a commitment to clinical trials and clinical investigation, and a comprehensive program for quality assurance. The advantages of FSCC to the community, to hospital programs, to the practicing surgical, medical, and radiation oncologists, and to the third-party carriers, including health maintenance organizations, are detailed. The development of an FSCC depends on the resolution of issues of (a) competition (between hospitals, hospitals and physicians, therapeutic disciplines, regional comprehensive cancer centers and FSCCs) and (b) concerns about conflict of interest. The ideal model of FSCC may well be represented by the joint venture of community hospital(s) and the community oncologists.

  9. 1x4 reconfigurable demultiplexing filter based on free-standing silicon racetrack resonators.

    Science.gov (United States)

    Dong, Po; Qian, Wei; Liang, Hong; Shafiiha, Roshanak; Wang, Xin; Feng, Dazeng; Li, Guoliang; Cunningham, John E; Krishnamoorthy, Ashok V; Asghari, Mehdi

    2010-11-22

    We present a 1x4 reconfigurable demultiplexing filter based on cascaded thermally tunable silicon racetrack resonators with ultralow tuning powers. The use of free-standing silicon resonators with undercut structures significantly reduces the tuning power, with a figure of ~2.9 mW per free spectral range. Even with the presence of thermal crosstalk between two adjacent resonators, we demonstrate multiplexing functionality for channel spacings of 200 GHz, 100 GHz, and 50 GHz, with channel wavelengths aligned to International Telecommunication Union (ITU) grid specifications. Crosstalk values for 200 GHz and 50 GHz channel spacings are less than -20 dB and -11.5 dB, respectively. The total power to achieve this performance is in the range of 1.84 mW to 2.4 mW. Such low-power, compact, and reconfigurable filters are particularly useful in chip-scale optical interconnects.

  10. Tuning optical and three photon absorption properties in graphene oxide-polyvinyl alcohol free standing films

    Science.gov (United States)

    Karthikeyan, B.; Udayabhaskar, R.; Hariharan, S.

    2016-07-01

    We report the optical and nonlinear optical properties of graphene oxide (GO)-polyvinyl alcohol (PVA) free standing films. The composite polymer films were prepared in ex-situ method. The variation in optical absorption spectra and optical constants with the amount of GO loading was noteworthy from the optical absorption spectroscopic studies. Nonlinear optical studies done at 532 nm using 5 ns laser pulses show three photon absorption like behaviour. Both steady state and time resolved fluorescence studies reveal that the GO was functioning as a pathway for the decay of fluorescence from PVA. This is attributed to the energy level modifications of GO through hydroxyl groups with PVA. Raman spectroscopy also supports the interaction between GO and PVA ions through OH radicals.

  11. Temperature and directional dependences of the infrared dielectric function of free standing silicon nanowire

    Energy Technology Data Exchange (ETDEWEB)

    Kazan, M.; Bruyant, A.; Sedaghat, Z.; Arnaud, L.; Blaize, S.; Royer, P. [Laboratoire de Nanotechnologie et d' Instrumentation Optique, Institut Charles Delaunay, Universite de Technologie de Troyes, CNRS FRE 2848, 12 Rue Marie Curie, 10010 Troyes, Cedex (France)

    2011-03-15

    An approach to calculate the infrared dielectric function of semiconductor nanostructures is presented and applied to silicon (Si) nanowires (NW's). The phonon modes symmetries and frequencies are calculated by means of the elastic continuum medium theory. The modes strengths and damping are calculated from a model for lattice dynamics and perturbation theory. The data are used in anisotropic Lorentz oscillator model to generate the temperature and directional dependences of the infrared dielectric function of free standing Si NW's. Our results showed that in the direction perpendicular to the NW axis, the complex dielectric function is identical to that of bulk Si. However, along the NW axis, the infrared dielectric function is a strong function of the wavelength. (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  12. The pyroelectric coefficient of free standing GaN grown by HVPE

    Science.gov (United States)

    Jachalke, Sven; Hofmann, Patrick; Leibiger, Gunnar; Habel, Frank S.; Mehner, Erik; Leisegang, Tilmann; Meyer, Dirk C.; Mikolajick, Thomas

    2016-10-01

    The present study reports on the temperature dependent pyroelectric coefficient of free-standing and strain-free gallium nitride (GaN) grown by hydride vapor phase epitaxy (HVPE). The Sharp-Garn method is applied to extract the pyroelectric coefficient from the electrical current response of the crystals subjected to a sinusoidal temperature excitation in a range of 0 °C to 160 °C. To avoid compensation of the pyroelectric response by an internal conductivity, insulating GaN crystals were used by applying C, Mn, and Fe doping during HVPE growth. The different pyroelectric coefficients observed at room temperature due to the doping correlate well with the change of the lattice parameter c. The obtained data are compared to previously published theoretical and experimental values of thin film GaN and discussed in terms of a strained lattice.

  13. A phase-field study of the scaling law in free-standing ferroelectric thin films

    Science.gov (United States)

    Yin, Binglun; Mao, Huina; Qu, Shaoxing

    2015-12-01

    The scaling law for ferroelectric stripe domains is investigated in free-standing BaTiO3 and PbTiO3 thin films via phase-field simulations. The results agree with the Kittel law, where the square of the domain width is found to be proportional to the thin film thickness. After being rescaled by the corresponding domain wall thickness, the generalized scaling law is also demonstrated, with the dimensionless scaling constant M estimated to be ˜3.3 in two ferroelectric materials. Moreover, we predict the effect of the exchange constant which is incorporated in Ginzburg-Landau theory on the equilibrium domain width and the critical thickness of the ferroelectric thin films.

  14. Fabrication of piezodriven, free-standing, all-oxide heteroepitaxial cantilevers on silicon

    Directory of Open Access Journals (Sweden)

    N. Banerjee

    2014-09-01

    Full Text Available We report on the fabrication and mechanical properties of all-oxide, free-standing, heteroepitaxial, piezoelectric, microelectromechanical systems (MEMS on silicon, using PbZr0.52Ti0.48O3 as the key functional material. The fabrication was enabled by the development of an epitaxial lift-off strategy for the patterning of multilayer oxide heterostructures grown on Si(001, employing a high temperature stable, sacrificial oxide template mask to obtain freestanding cantilever MEMS devices after substrate etching. All cantilevers, with lengths in the range 25–325 μm, width 50 μm, and total thickness of 300 nm, can be actuated by an external AC-bias. For lengths 50–125 μm, the second order bending mode formed the dominant resonance, whereas for the other lengths different or multiple modes were present.

  15. Rapid On-Site Formation of a Free-Standing Flexible Optical Link for Sensing Applications

    Directory of Open Access Journals (Sweden)

    Carlos Angulo Barrios

    2016-10-01

    Full Text Available An optical link, based on a conventional Scotch tape waveguide, for sensing applications requiring rapid on-site assembly is proposed and demonstrated. The flexible waveguide contains an integrated aluminum one-dimensional grating coupler that, when stuck on the radiative surface of a light emitting device, allows light to be coupled in and transmitted through the tape, whose tip end is, in turn, adhered onto the photosensitive surface of a photodetector. The (decoupling approaches exhibit high alignment tolerances that permit the formation of a free-standing flexible optical connection between surface-normal optoelectronic devices without the need of specialized equipment. As the first demonstration of a sensing application, the proposed optical link is easily configured as a cost-effective intensity-based refractometric sensor for liquid detection, which can be applicable to on-site quality and process control of, for example, beverages.

  16. Rapid On-Site Formation of a Free-Standing Flexible Optical Link for Sensing Applications

    Science.gov (United States)

    Barrios, Carlos Angulo

    2016-01-01

    An optical link, based on a conventional Scotch tape waveguide, for sensing applications requiring rapid on-site assembly is proposed and demonstrated. The flexible waveguide contains an integrated aluminum one-dimensional grating coupler that, when stuck on the radiative surface of a light emitting device, allows light to be coupled in and transmitted through the tape, whose tip end is, in turn, adhered onto the photosensitive surface of a photodetector. The (de)coupling approaches exhibit high alignment tolerances that permit the formation of a free-standing flexible optical connection between surface-normal optoelectronic devices without the need of specialized equipment. As the first demonstration of a sensing application, the proposed optical link is easily configured as a cost-effective intensity-based refractometric sensor for liquid detection, which can be applicable to on-site quality and process control of, for example, beverages. PMID:27782049

  17. Free-standing ZnO nanorods and nanowalls by aqueous solution method.

    Science.gov (United States)

    Kim, Dae-Hee; Lee, Sam-Dong; Kim, Kyoung-Kook; Park, Gyeong-Su; Lee, Ji-Myon; Kim, Sang-Woo

    2008-09-01

    Large quantity of free-standing ZnO nanorods and nanowalls were synthesized at low temperature of below 100 degrees C using zinc acetate, zinc nitrate hexahydrate, and hexamethylenetetramine by using a simple aqueous solution method. The general morphology of the grown ZnO nanostructures which include nanorods and nanowalls was strongly influenced by growth conditions. It was found that the grown ZnO nanorods are of a single-crystalline hexagonal structure and preferred c-axis growth orientation. ZnO nanorods were of better crystallinity than ZnO nanowalls, due to the higher growth temperature used to grow ZnO nanorods. Strong free exciton emission bands with relatively weak deep level emission were clearly observed from ZnO nanorods and nanowalls, indicating their good optical properties.

  18. Land use history and population dynamics of free-standing figs in a maturing forest

    Science.gov (United States)

    Albrecht, Larissa; Stallard, Robert F.; Kalko, Elisabeth K.V.

    2017-01-01

    Figs (Ficus sp.) are often considered as keystone resources which strongly influence tropical forest ecosystems. We used long-term tree-census data to track the population dynamics of two abundant free-standing fig species, Ficus insipida and F. yoponensis, on Barro Colorado Island (BCI), a 15.6-km2 island in Lake Gatún, Panama. Vegetation cover on BCI consists of a mosaic of old growth (>400 years) and maturing (about 90–150 year old) secondary rainforest. Locations and conditions of fig trees have been mapped and monitored on BCI for more than 35 years (1973–2011), with a focus on the Lutz Catchment area (25 ha). The original distribution of the fig trees shortly after the construction of the Panama Canal was derived from an aerial photograph from 1927 and was compared with previous land use and forest status. The distribution of both fig species (~850 trees) is restricted to secondary forest. Of the original 119 trees observed in Lutz Catchment in 1973, >70% of F. insipida and >90% of F. yoponensis had died by 2011. Observations in other areas on BCI support the trend of declining free-standing figs. We interpret the decline of these figs on BCI as a natural process within a maturing tropical lowland forest. Senescence of the fig trees appears to have been accelerated by severe droughts such as the strong El Niño event in the year 1982/83. Because figs form such an important food resource for frugivores, this shift in resource availability is likely to have cascading effects on frugivore populations.

  19. Free-standing coating patterns fabricated by ultraviolet contact lithography using photosensitive sol-gel coatings

    Science.gov (United States)

    Xiang, Youlai; Du, Ai; Li, Xiaoguang; Sun, Wei; Wu, Shuai; Li, Tiemin; Liu, Mingfang; Zhou, Bin

    2017-07-01

    Photosensitive ZrO2-SiO2 hybrid sol-gel coatings containing large contents of chelating rings were prepared by using the zirconium n-butoxide (TBOZ) and methyltriethoxysilane (MTES) as hybrid precursors, and benzoylacetone (BZAC) as chelating agent. The change of ultraviolet (UV) absorption spectra, chemical composition, and optical properties of ZrO2-SiO2 hybrid sol-gel coatings were analyzed before and after UV exposure and calcination. The refractive index of the ZrO2-SiO2 hybrid gel coatings decreased from 1.673 to 1.561 with the increase of the molar content of MTES in precursors. The sol-gel coating patterns with the periods of 20.24 μm, 10.11 μm and 3.99 μm on the PAMS substrates were firstly obtained by using the photosensitive ZrO2-SiO2 hybrid sol-gel films as fundamental materials through a process of UV contact lithography with photo masks and etching with ethanol. Finally, the free-standing gel coating patterns supported by copper grids, with the period of 12.70 μm and line width of 4.93 μm, and the period of 14.20 μm and line width of 3.82 μm, were obtained by removing the PAMS thermal degradation sacrifice layer after being calcined at 330 °C. Micrometer-periodic free-standing gel coating patterns with different structure have potential applications in the laser physical experiments.

  20. Copper Nanoparticle-Incorporated Carbon Fibers as Free-Standing Anodes for Lithium-Ion Batteries.

    Science.gov (United States)

    Han, Pan; Yuan, Tao; Yao, Long; Han, Zhuo; Yang, Junhe; Zheng, Shiyou

    2016-12-01

    Copper-incorporated carbon fibers (Cu/CF) as free-standing anodes for lithium-ion batteries are prepared by electrospinning technique following with calcination at 600, 700, and 800 °C. The structural properties of materials are characterized by X-ray diffraction (XRD), Raman, thermogravimetry (TGA), scanning electron microscopy (SEM), transmission electron microscope (TEM), and energy dispersive X-ray spectrometry (EDS). It is found that the Cu/CF composites have smooth, regular, and long fibrous morphologies with Cu nanoparticles uniformly dispersed in the carbon fibers. As free-standing anodes, the unique structural Cu/CF composites show stable and high reversible capacities, together with remarkable rate and cycling capabilities in Li-ion batteries. The Cu/CF calcined at 800 °C (Cu/CF-800) has the highest charge/discharge capacities, long-term stable cycling performance, and excellent rate performance; for instance, the Cu/CF-800 anode shows reversible charge/discharge capacities of around 800 mAh g(-1) at a current density of 100 mA g(-1) with stable cycling performance for more than 250 cycles; even when the current density increases to 2 A g(-1), the Cu/CF-800 anode can still deliver a capacity of 300 mAh g(-1). This excellent electrochemical performance is attributed to the special 1D structure of Cu/CF composites, the enhanced electrical conductivity, and more Li(+) active positions by Cu nanoinclusion.

  1. Multilayer Transparent Top Electrode for Solution Processed Perovskite/Cu(In,Ga)(Se,S)2 Four Terminal Tandem Solar Cells.

    Science.gov (United States)

    Yang, Yang Michael; Chen, Qi; Hsieh, Yao-Tsung; Song, Tze-Bin; Marco, Nicholas De; Zhou, Huanping; Yang, Yang

    2015-07-28

    Halide perovskites (PVSK) have attracted much attention in recent years due to their high potential as a next generation solar cell material. To further improve perovskites progress toward a state-of-the-art technology, it is desirable to create a tandem structure in which perovskite may be stacked with a current prevailing solar cell such as silicon (Si) or Cu(In,Ga)(Se,S)2 (CIGS). The transparent top electrode is one of the key components as well as challenges to realize such tandem structure. Herein, we develop a multilayer transparent top electrode for perovskite photovoltaic devices delivering an 11.5% efficiency in top illumination mode. The transparent electrode is based on a dielectric/metal/dielectric structure, featuring an ultrathin gold seeded silver layer. A four terminal tandem solar cell employing solution processed CIGS and perovskite cells is also demonstrated with over 15% efficiency.

  2. Free-standing TiO{sub 2} nanotube arrays made by anodic oxidation and ultrasonic splitting

    Energy Technology Data Exchange (ETDEWEB)

    Chen Qingwei; Xu Dongsheng; Wu Zhongyun; Liu Zhongfan [Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Structural Chemistry of Unstable and Stable Species, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871 (China)], E-mail: dsxu@pku.edu.cn

    2008-09-10

    A facile and green method was employed to prepare large-scale free-standing TiO{sub 2} nanotube (TNT) arrays, in which as-anodized TiO{sub 2} nanotube films prepared in organic electrolytes with thickness ranging from seven to tens of micrometers were then ultrasonicated in a mix solution of ethanol and water. By controlling the ratio of ethanol to water, the time and the power of ultrasonication, large-scale free-standing TiO{sub 2} nanotube arrays without any crack could be detached from the Ti substrates. Hydrogen sensing results demonstrated that the free-standing TNT film is more sensitive than a film with Ti substrates when exposed to 1000 ppm hydrogen ambient.

  3. Free standing diamond-like carbon thin films by PLD for laser based electrons/protons acceleration

    Energy Technology Data Exchange (ETDEWEB)

    Thema, F.T.; Beukes, P.; Ngom, B.D. [UNESCO Africa Chair in Nanosciences-Nanotechnology, College of Graduate Studies, University of South Africa, Muckleneuk Ridge, PO Box 392, Pretoria (South Africa); Nanosciences African Network (NANOAFNET), iThemba LABS-National Research Foundation, 1 Old Faure Road, Somerset West, 7129, PO Box722, Western Cape Province (South Africa); Manikandan, E., E-mail: mani@tlabs.ac.za [UNESCO Africa Chair in Nanosciences-Nanotechnology, College of Graduate Studies, University of South Africa, Muckleneuk Ridge, PO Box 392, Pretoria (South Africa); Nanosciences African Network (NANOAFNET), iThemba LABS-National Research Foundation, 1 Old Faure Road, Somerset West, 7129, PO Box722, Western Cape Province (South Africa); Central Research Laboratory, Sree Balaji Medical College & Hospital (SBMCH), Chrompet, Bharath University, Chennai, 600044 (India); Maaza, M., E-mail: maaza@tlabs.ac.za [UNESCO Africa Chair in Nanosciences-Nanotechnology, College of Graduate Studies, University of South Africa, Muckleneuk Ridge, PO Box 392, Pretoria (South Africa); Nanosciences African Network (NANOAFNET), iThemba LABS-National Research Foundation, 1 Old Faure Road, Somerset West, 7129, PO Box722, Western Cape Province (South Africa)

    2015-11-05

    This study we reports for the first time on the synthesis and optical characteristics of free standing diamond-like carbon (DLC) deposited by pulsed laser deposition (PLD) onto graphene buffer layers for ultrahigh intensity laser based electron/proton acceleration applications. The fingerprint techniques of micro-Raman, UV–VIS–NIR and the IR spectroscopic investigations indicate that the suitability of such free standing DLC thin-films within the laser window and long wave infrared (LWIR) spectral range and hence their appropriateness for the targeted applications. - Highlights: • We report for the first time synthesis of free standing diamond-like carbon. • Pulsed laser deposition onto graphene buffer layers. • Fingerprint techniques of micro-Raman, UV–VIS–NIR and the IR spectroscopic investigations. • Ultrahigh intensity laser based electron/proton acceleration applications. • This material's suitable for the laser window and long wave infrared (LWIR) spectral range.

  4. Quasi-free-standing bilayer epitaxial graphene field-effect transistors on 4H-SiC (0001) substrates

    Energy Technology Data Exchange (ETDEWEB)

    Yu, C.; Li, J.; Song, X. B.; Liu, Q. B.; Cai, S. J.; Feng, Z. H., E-mail: ga917vv@163.com [National Key Laboratory of ASIC, Hebei Semiconductor Research Institute, Shijiazhuang 050051 (China); He, Z. Z. [National Key Laboratory of ASIC, Hebei Semiconductor Research Institute, Shijiazhuang 050051 (China); School of Electronic and Information Engineering, Hebei University of Technology, Tianjin 300130 (China)

    2016-01-04

    Quasi-free-standing epitaxial graphene grown on wide band gap semiconductor SiC demonstrates high carrier mobility and good material uniformity, which make it promising for graphene-based electronic devices. In this work, quasi-free-standing bilayer epitaxial graphene is prepared and its transistors with gate lengths of 100 nm and 200 nm are fabricated and characterized. The 100 nm gate length graphene transistor shows improved DC and RF performances including a maximum current density I{sub ds} of 4.2 A/mm, and a peak transconductance g{sub m} of 2880 mS/mm. Intrinsic current-gain cutoff frequency f{sub T} of 407 GHz is obtained. The exciting DC and RF performances obtained in the quasi-free-standing bilayer epitaxial graphene transistor show the great application potential of this material system.

  5. High-performance semitransparent perovskite solar cells with solution-processed silver nanowires as top electrodes.

    Science.gov (United States)

    Guo, Fei; Azimi, Hamed; Hou, Yi; Przybilla, Thomas; Hu, Mengyao; Bronnbauer, Carina; Langner, Stefan; Spiecker, Erdmann; Forberich, Karen; Brabec, Christoph J

    2015-02-07

    In this work, we report efficient semitransparent perovskite solar cells using solution-processed silver nanowires (AgNWs) as top electrodes. A thin layer of zinc oxide nanoparticles is introduced beneath the AgNWs, which fulfills two essential functionalities: it ensures ohmic contact between the PC60BM and the AgNWs and it serves as a physical foundation that enables the solution-deposition of AgNWs without causing damage to the underlying perovskite. The as-fabricated semitransparent perovskite cells show a high fill factor of 66.8%, Voc = 0.964 V, Jsc = 13.18 mA cm(-2), yielding an overall efficiency of 8.49% which corresponds to 80% of the reference devices with reflective opaque electrodes.

  6. FACILE REGULATION OF GLUTARALDEHYDE-MODIFIED GRAPHENE OXIDE FOR PREPARING FREE-STANDING PAPERS AND NANOCOMPOSITE FILMS

    Institute of Scientific and Technical Information of China (English)

    Ye-qiang Tan; Yi-hu Song; Qiang Zheng

    2013-01-01

    Colloidal suspensions of glutaraldehyde (GA) crosslinked or grafted graphene oxide (GO) sheets were fabricated by simply tailoring the feed sequence.The different structures were confirmed by Fourier transform infrared spectra and X-ray diffraction.As demonstration of the utilities,the different colloidal suspensions were used to prepare free-standing papers by flow-directed filtration and poly(vinyl alcohol) (PVA)-based nanocomposite films by casting.Free-standing papers from GA crosslinked GO sheets exhibited better mechanical properties than unmodified GO paper,while nanocomposite films from GA grafted GO exhibit higher tensile strength and Young's modulus.

  7. Modeling and experimental investigations of Fano resonances in free-standing LiNbO3 photonic crystal slabs.

    Science.gov (United States)

    Deng, Jun; Hussain, Sajid; Kumar, Vanga Sudheer; Jia, Wei; Png, Ching Eng; Thor, Lim Soon; Bettiol, Andrew A; Danner, Aaron J

    2013-02-11

    In this paper the Fano resonance in a free-standing LiNbO(3) photonic crystal slab is demonstrated. We present a numerical analysis and experimental measurements with free space illumination where the dependence of slab thickness, radius of air holes and lattice types are investigated. The unique property of polarization dependence for LiNbO(3) photonic crystal slabs is also analyzed, and we show that the transmission spectra exhibit significant sensitivity (~25nm) to polarization. A monolithic free-standing LiNbO(3) photonic crystal slab was fabricated using ion beam enhanced etching (IBEE) technology. Measurement results of the reflection spectra agree with the numerical analysis.

  8. On the compliant behaviour of free-standing Si nanostructures on Si(001) for Ge nanoheteroepitaxy

    Energy Technology Data Exchange (ETDEWEB)

    Kozlowski, Grzegorz

    2012-04-24

    Selective chemical vapor deposition Ge heteroepitaxy approaches for high quality Ge nanostructure growth with reasonable thermal budget must be developed for local Ge photonic module integration. A promising vision is offered by the compliant substrate effects within nanometer scale Ge/Si heteroepitaxial structures. Here, in contrast to the classical Ge deposition on bulk Si substrates, the thermal and lattice mismatch strain energy accumulated in the Ge epilayer is partially shifted to the free-standing Si nanostructure. This strain partitioning phenomenon is at the very heart of the nanoheteroepitaxy theory (NHE) and, if strain energy levels are correctly balanced, offers the vision to grow defect-free nanostructures of lattice mismatched semiconductors on Si. In case of the Ge/Si heterosystem with a lattice mismatch of 4.2%, the strain partitioning phenomenon is expected to be triggered when free-standing Si nanopillars with the width of 50 nm and below are used. In order to experimentally verify NHE with its compliant substrate effects, a set of free-standing Ge/Si nanostructures with diameter ranging from 150 to 50 nm were fabricated and investigated. The main limitation corresponds to a simultaneous detection of (a) the strain partitioning phenomenon between Ge and Si and (b) the absence of defects on the nano-scale. In this respect, synchrotron-based grazing incidence X-ray diffraction was applied to study the epitaxial relationship, defect and strain characteristics with high resolution and sensitivity in a non-destructive way. Raman spectroscopy supported by finite element method calculations were used to investigate the strain distribution within a single Ge/Si nanostructure. Special focus was devoted to transmission electron microscopy to determine the quality of the Ge epilayer. It was found, that although high quality Ge nanoclusters can be achieved by thermal annealing on Si pillars bigger than 50 nm in width, no proof of strain partitioning

  9. Towards free-standing graphene/carbon nanotube composite films via acetylene-assisted thermolysis of organocobalt functionalized graphene sheets.

    Science.gov (United States)

    Su, Qi; Liang, Yanyu; Feng, Xinliang; Müllen, Klaus

    2010-11-21

    A novel approach towards highly conductive free-standing chemically reduced graphene/carbon nanotube composite films via an in situ thermolysis of functionalized graphene/organic cobalt complexes was developed. By combining 1D-CNT and 2D-graphene, a synergistic effect of conductivity was established.

  10. A setup for transmission measurements of low energy multiply charged ions through free-standing few atomic layer films

    Science.gov (United States)

    Smejkal, V.; Gruber, E.; Wilhelm, R. A.; Brandl, L.; Heller, R.; Facsko, S.; Aumayr, F.

    2016-09-01

    We report the design and testing of a setup for transmission measurements of multiply charged ions through free-standing films with a thickness of a few atomic layers. The investigation thereof can yield deeper insight into charge equilibration and pre-equilibrium stopping phenomena which can ultimately be used to specifically tailor and modify these materials.

  11. In situ observation of the formation process for free-standing Au nanowires with a scanning electron microscope

    Science.gov (United States)

    Aiba, Akira; Kaneko, Satoshi; Fujii, Shintaro; Nishino, Tomoaki; Tsukagoshi, Kazuhito; Kiguchi, Manabu

    2017-03-01

    We have developed a simultaneous electronic and structural characterization method for studying the formation process for Au nanowires. The method is based on two-probe electronic transport measurement of free-standing Au nanowires and simultaneous structural characterization using scanning electron microscopy (SEM). We measured the electronic currents during the electromigration (EM)-induced narrowing process for the free-standing Au nanowires. A free-standing Au nanowire with a desired conductance value was fabricated by EM. Simultaneous SEM and conductance measurements revealed the EM-induced narrowing process for the Au wires, in which material transfer in the nanowires caused growth towards the positively biased electrode and contact failure at the negatively biased electrode. The narrowed free-standing Au nanowires were stable and could be maintained for more than 10 h without their conductance changing. These results indicate the high stability of the EM-processed Au nanowires compared to Au nanowires fabricated by mechanical elongation or the breaking of Au nanocontacts.

  12. Large-scale fabrication of free-standing, micropatterned silica nanotubes via a hybrid hydrogel-templated route.

    Science.gov (United States)

    Chen, Song; Shi, Xuetao; Chinnathambi, Shanmugavel; Hanagata, Nobutaka

    2013-08-01

    Free-standing, micropatterned silica nanotube membranes are in situ fabricated using a micropatterned silica-coated collagen hybrid hydrogel as template. They are substrate-free, and not only maintained their micropatterned microstructure well, but also exhibited strong cell contact guidance ability to direct cell alignment and differentiation, indicating their good potential for biomedical applications.

  13. On the structure and topography of free-standing chemically modified graphene

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, N R; Pandey, P A; Beanland, R; Lupo, U; Rowlands, G; Roemer, R A [Department of Physics, University of Warwick, Gibbet Hill Road, Coventry, CV4 7AL (United Kingdom); Rourke, J P, E-mail: Neil.Wilson@Warwick.ac.uk [Department of Chemistry, University of Warwick, Gibbet Hill Road, Coventry, CV4 7AL (United Kingdom)

    2010-12-15

    The mechanical, electrical and chemical properties of chemically modified graphene (CMG) are intrinsically linked to its structure. Here, we report on our study of the topographic structure of free-standing CMG using atomic force microscopy (AFM) and electron diffraction. We find that, unlike graphene, suspended sheets of CMG are corrugated and distorted on nanometre length scales. AFM reveals not only long-range (100 nm) distortions induced by the support, as previously observed for graphene, but also short-range corrugations with length scales down to the resolution limit of 10 nm. These corrugations are static not dynamic, and are significantly diminished on CMG supported on atomically smooth substrates. Evidence for even shorter-range distortions, down to a few nanometres or less, is found by electron diffraction of suspended CMG. Comparison of the experimental data with simulations reveals that the mean atomic displacement from the nominal lattice position is of order 10% of the carbon-carbon bond length. Taken together, these results suggest a complex structure for CMG where heterogeneous functionalization creates local strain and distortion.

  14. On the structure and topography of free-standing chemically modified graphene

    Science.gov (United States)

    Wilson, N. R.; Pandey, P. A.; Beanland, R.; Rourke, J. P.; Lupo, U.; Rowlands, G.; Römer, R. A.

    2010-12-01

    The mechanical, electrical and chemical properties of chemically modified graphene (CMG) are intrinsically linked to its structure. Here, we report on our study of the topographic structure of free-standing CMG using atomic force microscopy (AFM) and electron diffraction. We find that, unlike graphene, suspended sheets of CMG are corrugated and distorted on nanometre length scales. AFM reveals not only long-range (100 nm) distortions induced by the support, as previously observed for graphene, but also short-range corrugations with length scales down to the resolution limit of 10 nm. These corrugations are static not dynamic, and are significantly diminished on CMG supported on atomically smooth substrates. Evidence for even shorter-range distortions, down to a few nanometres or less, is found by electron diffraction of suspended CMG. Comparison of the experimental data with simulations reveals that the mean atomic displacement from the nominal lattice position is of order 10% of the carbon-carbon bond length. Taken together, these results suggest a complex structure for CMG where heterogeneous functionalization creates local strain and distortion.

  15. Local-fields and disorder effects in free-standing and embedded Si nanocrystallites

    Energy Technology Data Exchange (ETDEWEB)

    Guerra, Roberto [S3-Istituto Nanoscienze CNR, Modena (Italy); Dipartimento di Fisica, Universita di Modena e Reggio Emilia, Modena (Italy); Degoli, Elena; Ossicini, Stefano [Dipartimento di Scienze e Metodi dell' Ingegneria, Universita di Modena e Reggio Emilia, Reggio Emilia (Italy); S3-Istituto Nanoscienze CNR, Reggio Emilia (Italy); Marsili, Margherita; Pulci, Olivia [Dipartimento di Fisica dell' Universita di Roma Tor Vergata (Italy); European Theoretical Spectroscopy Facility (ETSF), CNR-INFM-SMC, NAST, Roma (Italy)

    2010-08-15

    The case study of a 32-atoms Si nanocrystallite (NC) embedded in a SiO{sub 2} matrix, both crystalline and amorphous, or free-standing with different conditions of passivation and strain is analyzed through ab-initio approaches. The Si{sub 32}/SiO{sub 2} heterojunction shows a type I band offset highlighting a separation between the NC plus the interface and the matrix around. The consequence of this separation is the possibility to correctly reproduce the low energy electronic and optical properties of the composed system simply by studying the suspended NC plus interface oxygens with the appropriate strain. Moreover, through the definition of an optical absorption threshold we found that, beside the quantum confinement trend, the amorphization introduces an additional redshift that increases with increasing NC size, i.e. the gap tends faster to the bulk limit. Finally, the important changes in the calculated DFT-RPA optical spectra upon inclusion of local fields point towards the need of a proper treatment of the optical response of the interface region. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  16. High-temperature Infrared Transmission of Free-standing Diamond Films

    Directory of Open Access Journals (Sweden)

    HEI Li-fu

    2017-02-01

    Full Text Available The combination of low absorption and extreme mechanical and thermal properties make diamond a compelling choice for some more extreme far infrared (8-12 μm window applications. The optical properties of CVD diamond at elevated temperatures are critical to many of these extreme applications. The infrared transmission of free-standing diamond films prepared by DC arc plasma jet were studied at temperature varied conditions. The surface morphology, structure feature and infrared optical properties of diamond films were tested by optical microscope, X-ray diffraction, laser Raman and Fourier-transform infrared spectroscopy. The results show that the average transmittance for 8-12μm is decreased from 65.95% at 27℃ to 52.5% at 500℃,and the transmittance drop is in three stages. Corresponding to the drop of transmittance with the temperature, diamond film absorption coefficient increases with the rise of temperature. The influence of the change of surface state of diamond films on the optical properties of diamond films is significantly greater than the influence on the internal structure.

  17. Free-Standing Graphene Oxide-Palygorskite Nanohybrid Membrane for Oil/Water Separation.

    Science.gov (United States)

    Zhao, Xueting; Su, Yanlei; Liu, Yanan; Li, Yafei; Jiang, Zhongyi

    2016-03-01

    Graphene oxide (GO) is an emerging kind of building block for advanced membranes with tunable passageway for water molecules. To synergistically manipulate the channel and surface structures/properties of GO-based membranes, the different building blocks are combined and the specific interfacial interactions are designed in this study. With vacuum-assisted filtration self-assembly, palygorskite nanorods are intercalated into adjacent GO nanosheets, and GO nanosheets are assembled into laminate structures through π-π stacking and cation cross-linking. The palygorskite nanorods in the free-standing GOP nanohybrid membranes take a 3-fold role, rendering enlarged mass transfer channels, elevating hydration capacity, and creating hierarchical nanostructures of membrane surfaces. Accordingly, the permeate fluxes from 267 L/(m(2) h) for GO membrane to 1867 L/(m(2) h) for GOP membrane. The hydration capacity and hierarchical nanostructures synergistically endow GOP membranes with underwater superoleophobic and low oil-adhesive water/membrane interfaces. Moreover, by rationally imparting chemical and physical joint defense mechanisms, the GOP membranes exhibit outstanding separation performance and antifouling properties for various oil-in-water emulsion systems (with different concentration, pH, or oil species). The high water permeability, high separation efficiency, as well as superior anti-oil-fouling properties of GOP membranes enlighten the great prospects of graphene-based nanostructured materials in water purification and wastewater treatment.

  18. Survey of Patient Knowledge and Expectations about a Free-Standing Emergency Department

    Directory of Open Access Journals (Sweden)

    Christopher Bucciarelli

    2015-01-01

    Full Text Available Objectives. A free-standing emergency department (FSED is defined as a facility that is structurally separate and distinct from a hospital and provides emergency care. Nationally, the number of FSEDs continues to grow, but the general public may have limited knowledge about the costs and services associated with FSEDs. The purpose of this paper is to survey patient knowledge and expectations about FSEDs. Methods. A convenience sample of patients presenting to a FSED was given a 19-item survey to complete. Results. 187 surveys were collected; 126 were included for analysis. 40% of respondents thought they could be seen by a specialist at the FSED, and 55% of patients did not know they had to be transferred for hospitalization if required. Most patients did not know that the cost of services at the FSED would be the same as that at the traditional ED. Convenience and perceived shorter wait times were the primary reasons patients selected the FSED for care. Conclusion. In general, patients do not have adequate knowledge about the costs and services associated with FSEDs. Education through marketing and advertising may be helpful in creating more public awareness about FSEDs.

  19. Polarized infrared reflectance study of free standing cubic GaN grown by molecular beam epitaxy

    Energy Technology Data Exchange (ETDEWEB)

    Lee, S.C., E-mail: saicheonglee86@yahoo.com [Nano-Optoelectronics Research Laboratory, School of Physics, Universiti Sains Malaysia, 11800 Penang (Malaysia); Department of Physics, Faculty of Science, University of Malaya, 50603 Kuala Lumpur (Malaysia); Ng, S.S.; Hassan, H. Abu; Hassan, Z.; Zainal, N. [Nano-Optoelectronics Research Laboratory, School of Physics, Universiti Sains Malaysia, 11800 Penang (Malaysia); Novikov, S.V.; Foxon, C.T.; Kent, A.J. [School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD (United Kingdom)

    2014-07-01

    Optical properties of free standing cubic gallium nitride grown by molecular beam epitaxy system are investigated by a polarized infrared (IR) reflectance technique. A strong reststrahlen band, which reveals the bulk-like optical phonon frequencies, is observed. Meanwhile, continuous oscillation fringes, which indicate the sample consists of two homogeneous layers with different dielectric constants, are observed in the non-reststrahlen region. By obtaining the first derivative of polarized IR reflectance spectra measured at higher angles of incidence, extra phonon resonances are identified at the edges of the reststrahlen band. The observations are verified with the theoretical results simulated based on a multi-oscillator model. - Highlights: • First time experimental studies of IR optical phonons in bulk like, cubic GaN layer. • Detection of extra phonon modes of cubic GaN by polarized IR reflectance technique. • Revelation of IR multiphonon modes of cubic GaN by first derivative numerical method. • Observation of multiphonon modes requires very high angle of incidence. • Resonance splitting effect induced by third phonon mode is a qualitative indicator.

  20. Three-dimensional free-standing carbon nanotubes for a flexible lithium-ion battery anode

    Science.gov (United States)

    Kang, Chiwon; Cha, Eunho; Baskaran, Rangasamy; Choi, Wonbong

    2016-03-01

    Flexible lithium-ion batteries (LIBs) have received considerable attention as energy sources for wearable electronics. In recent years, much effort has been devoted to study light-weight, robust, and flexible electrodes. However, high areal and volumetric capacities need to be achieved for practical power and energy densities. In this paper, we report the use of three-dimensional (3D) free-standing carbon nanotubes (CNTs) as a current collector-free anode to demonstrate flexible LIBs with enhanced areal and volumetric capacities. High density CNTs grown on copper (Cu) mesh are transferred to a flexible graphene/polyethylene terephthalate film and integrated into a flexible LIB. A fully flexible LIB cell integrated with the 3D CNT anode delivers a high areal capacity of 0.25 mAh cm-2 at 0.1C and shows fairly consistent open circuit voltage under bending. These findings may provide significant advances in the application of flexible LIB based electronic devices.

  1. Scalable Approach To Construct Free-Standing and Flexible Carbon Networks for Lithium–Sulfur Battery

    KAUST Repository

    Li, Mengliu

    2017-02-21

    Reconstructing carbon nanomaterials (e.g., fullerene, carbon nanotubes (CNTs), and graphene) to multidimensional networks with hierarchical structure is a critical step in exploring their applications. Herein, a sacrificial template method by casting strategy is developed to prepare highly flexible and free-standing carbon film consisting of CNTs, graphene, or both. The scalable size, ultralight and binder-free characteristics, as well as the tunable process/property are promising for their large-scale applications, such as utilizing as interlayers in lithium-sulfur battery. The capability of holding polysulfides (i.e., suppressing the sulfur diffusion) for the networks made from CNTs, graphene, or their mixture is pronounced, among which CNTs are the best. The diffusion process of polysulfides can be visualized in a specially designed glass tube battery. X-ray photoelectron spectroscopy analysis of discharged electrodes was performed to characterize the species in electrodes. A detailed analysis of lithium diffusion constant, electrochemical impedance, and elementary distribution of sulfur in electrodes has been performed to further illustrate the differences of different carbon interlayers for Li-S batteries. The proposed simple and enlargeable production of carbon-based networks may facilitate their applications in battery industry even as a flexible cathode directly. The versatile and reconstructive strategy is extendable to prepare other flexible films and/or membranes for wider applications.

  2. Scalable Approach To Construct Free-Standing and Flexible Carbon Networks for Lithium-Sulfur Battery.

    Science.gov (United States)

    Li, Mengliu; Wahyudi, Wandi; Kumar, Pushpendra; Wu, Fengyu; Yang, Xiulin; Li, Henan; Li, Lain-Jong; Ming, Jun

    2017-03-08

    Reconstructing carbon nanomaterials (e.g., fullerene, carbon nanotubes (CNTs), and graphene) to multidimensional networks with hierarchical structure is a critical step in exploring their applications. Herein, a sacrificial template method by casting strategy is developed to prepare highly flexible and free-standing carbon film consisting of CNTs, graphene, or both. The scalable size, ultralight and binder-free characteristics, as well as the tunable process/property are promising for their large-scale applications, such as utilizing as interlayers in lithium-sulfur battery. The capability of holding polysulfides (i.e., suppressing the sulfur diffusion) for the networks made from CNTs, graphene, or their mixture is pronounced, among which CNTs are the best. The diffusion process of polysulfides can be visualized in a specially designed glass tube battery. X-ray photoelectron spectroscopy analysis of discharged electrodes was performed to characterize the species in electrodes. A detailed analysis of lithium diffusion constant, electrochemical impedance, and elementary distribution of sulfur in electrodes has been performed to further illustrate the differences of different carbon interlayers for Li-S batteries. The proposed simple and enlargeable production of carbon-based networks may facilitate their applications in battery industry even as a flexible cathode directly. The versatile and reconstructive strategy is extendable to prepare other flexible films and/or membranes for wider applications.

  3. Oriented free-standing ammonium vanadium oxide nanobelt membranes: highly selective absorbent materials.

    Science.gov (United States)

    Zou, Rujia; Zhang, Zhenyu; Yu, Li; Tian, Qiwei; Wu, Jianghong; Sun, Yangang; Chen, Zhigang; Hu, Junqing

    2010-12-27

    Highly selective, absorbent, free-standing, paper-like membranes made of ammonium vanadium oxide (NH(4)V(4)O(14)) nanobelts have been engineered by taking advantage of the nanoscaled self-assembly of architectures that display a mesh structure with an average periodic pore size of about 5 to 10 nm. The NH(4)V(4)O(14) nanobelts are synthesized by using a simple hydrothermal process, and exhibit the same orientation and assemble into bundles, each about 40 to 80 nm in width, 3 to 5 nm in thickness, and up to several millimeters in length. Importantly, the as-obtained NH(4)V(4)O(14) nanobelt membranes can highly selectively absorb a variety of organic solvents, covering both polar and non-polar solvents, for example, the absorbent capacity of glycol is 28 times as high as the initial weight of the membrane, and it can even separate organic solvents with similar polarities and absorb solid contaminants in organic solvents. These highly selective, absorbent membrane materials can be an ideal candidate for the separation and removal of pollution in industrial and environmental applications.

  4. Free-standing porous supramolecular assemblies of nanoparticles made using a double-templating strategy.

    Science.gov (United States)

    Ling, Xing Yi; Phang, In Yee; Reinhoudt, David N; Vancso, G Julius; Huskens, Jurriaan

    2009-01-01

    The formation of stable and ordered free-standing porous supramolecular assemblies of nanoparticles with sizes and geometries controlled at different length scales is demonstrated by a double-templating strategy. Our technique combines the directed assembly of particles, templating using nanoimprint lithography (NIL), and supramolecular layer-by-layer (LbL) assembly. First, 500-nm beta-cyclodextrin (CD)-functionalized polystyrene (PS) particles were assembled by convective assembly onto a sacrificial polymer template patterned with a predefined geometry and size using NIL, forming a 3D crystal architecture of particles. LbL assembly of alternating supramolecular host- and guest-functionalized glues of CD-functionalized Au (Au-CD) nanoparticles and adamantyl (Ad) dendrimers, sized between 3-5 nm, within the preformed PS-particle crystal effectively bound the particles together into a particle composite. These particle composites were released from the substrate together with the polymer template, and transferred onto a target substrate. The particle crystal integrity, order and functionality were preserved. Rinsing the structure with dichloromethane removed the PS core material together with the polymer template, resulting in interconnected porous capsules, the sizes and shapes of which are fully determined by the PS core size and the polymer template definition. Again, integrity and shape were preserved in the rinsing step. These capsules were capable of storing organic fluorescent molecules using specific interactions.

  5. Ultrahigh throughput plasma processing of free standing silicon nanocrystals with lognormal size distribution

    Energy Technology Data Exchange (ETDEWEB)

    Dogan, Ilker; Kramer, Nicolaas J.; Westermann, Rene H. J.; Verheijen, Marcel A. [Department of Applied Physics, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven (Netherlands); Dohnalova, Katerina; Gregorkiewicz, Tom [Van der Waals-Zeeman Institute, University of Amsterdam, Science Park 904, 1098 XH Amsterdam (Netherlands); Smets, Arno H. M. [Photovoltaic Materials and Devices Laboratory, Delft University of Technology, P.O. Box 5031, 2600 GA Delft (Netherlands); Sanden, Mauritius C. M. van de [Department of Applied Physics, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven (Netherlands); Dutch Institute for Fundamental Energy Research (DIFFER), P.O. Box 1207, 3430 BE Nieuwegein (Netherlands)

    2013-04-07

    We demonstrate a method for synthesizing free standing silicon nanocrystals in an argon/silane gas mixture by using a remote expanding thermal plasma. Transmission electron microscopy and Raman spectroscopy measurements reveal that the distribution has a bimodal shape consisting of two distinct groups of small and large silicon nanocrystals with sizes in the range 2-10 nm and 50-120 nm, respectively. We also observe that both size distributions are lognormal which is linked with the growth time and transport of nanocrystals in the plasma. Average size control is achieved by tuning the silane flow injected into the vessel. Analyses on morphological features show that nanocrystals are monocrystalline and spherically shaped. These results imply that formation of silicon nanocrystals is based on nucleation, i.e., these large nanocrystals are not the result of coalescence of small nanocrystals. Photoluminescence measurements show that silicon nanocrystals exhibit a broad emission in the visible region peaked at 725 nm. Nanocrystals are produced with ultrahigh throughput of about 100 mg/min and have state of the art properties, such as controlled size distribution, easy handling, and room temperature visible photoluminescence.

  6. Ultrathin free-standing polyelectrolyte nanocomposites: a novel method for preparation and characterization of assembly dynamics.

    Science.gov (United States)

    Ferri, James K; Dong, Wen-Fei; Miller, Reinhard

    2005-08-11

    We present a new opportunity for the investigation of the dynamics of electrostatic ultrathin-film assembly and the elucidation of time scales required for layer-by-layer adsorption of polyelectrolytes using a novel pendant drop technique which allows for the synthesis of free-standing nanocomposites. In short, a charged molecular template, i.e., a lipid monolayer, is deposited on a pendant drop and compressed to present a defined surface charge density to the subphase of the drop. The subphase is then cycled alternatively between solutions of polycations, saline, and polyanions by injection and withdrawal of liquid from coaxial capillaries on which the drop was formed, resulting in encapsulation of the drop volume by a polymeric composite membrane. The in situ dynamics of the process are followed by axisymmetric drop shape analysis. As a model, nanocomposites of dimyristoyl phosphatidyl glycerol-(polyallylamine hydrochloride/polystyrene sulfonate)(n=1-3) were prepared. The characteristic time scales for assembly range from 1 to 4 min and increase with film thickness. It is also demonstrated that small-amplitude (>1%) perturbations in the film density during adsorption prolong the assembly. Both these results underscore the nonequilibrium nature of these materials.

  7. Free standing luminescent silicon quantum dots: evidence of quantum confinement and defect related transitions

    Energy Technology Data Exchange (ETDEWEB)

    Ray, Mallar [School of Materials Science and Engineering, Bengal Engineering and Science University, Shibpur, Howrah: 711103, West Bengal (India); Hossain, Syed Minhaz [Department of Physics, Bengal Engineering and Science University, Shibpur, Howrah: 711103, West Bengal (India); Klie, Robert F [Department of Physics, University of Illinois at Chicago, Chicago, IL 60607 (United States); Banerjee, Koushik; Ghosh, Siddhartha, E-mail: mray@matsc.becs.ac.in [Department of Electrical and Computer Engineering, University of Illinois at Chicago, Chicago, 60607 (United States)

    2010-12-17

    We report the synthesis of luminescent, free standing silicon quantum dots by dry and wet etching of silicon and silicon oxide core/shell nanostructures, which are synthesized by controlled oxidation of mechanically milled silicon. Dry and wet etching performed with CF{sub 4} plasma and aqueous HF, respectively, result in the removal of the thick oxide shell of the core/shell nanostructures and affect an additional step of size reduction. HF etch is capable of producing isolated, spherical quantum dots of silicon with dimensions {approx} 2 nm. However, the etching processes introduce unsaturated bonds at the surface of the nanocrystals which are subsequently passivated by oxygen on exposure to ambient atmosphere. The photoluminescence spectra of the colloidal suspensions of these nanocrystals are characterized by double peaks and excitation dependent shift of emission energy. Comparison of the structural, absorption and luminescence characteristics of the samples provides evidence for two competing transition processes-quantum confinement induced widened band gap related transitions and oxide associated interface state mediated transitions. The results enable us to experimentally distinguish between the contributions of the two different transition mechanisms, which has hitherto been a challenging problem.

  8. Initiation of long, free-standing z discharges by CO2 laser gas heating

    Science.gov (United States)

    Niemann, C.; Tauschwitz, A.; Penache, D.; Neff, S.; Knobloch, R.; Birkner, R.; Presura, R.; Hoffmann, D. H. H.; Yu, S. S.; Sharp, W. M.

    2002-01-01

    High current discharge channels can neutralize both current and space charge of very intense ion beams. Therefore, they are considered an interesting solution for final focus and beam transport in a heavy ion beam fusion reactor. At the Gesellschaft für Schwerionenforschung accelerator facility, 50 cm long, free-standing discharge channels were created in a 60 cm diameter metallic chamber. Discharges with currents of 45 kA in 2 to 25 mbar ammonia (NH3) gas are initiated by a CO2 laser pulse along the channel axis before the capacitor bank is triggered. Resonant absorption of the laser, tuned to the v2 vibration of the ammonia molecule, causes strong gas heating. Subsequent expansion and rarefaction of the gas prepare the conditions for a stable discharge to fulfill the requirements for ion beam transport. The influence of an electric prepulse on the high current discharge was investigated. This article describes the laser-gas interaction and the discharge initiation mechanism. We found that channels are magnetohydrodynamic stable up to currents of 45 kA, measured by fast shutter and streak imaging techniques. The rarefaction of the laser heated gas is studied by means of a one-dimensional Lagrangian fluid code (CYCLOPS) and is identified as the dominant initiation mechanism of the discharge.

  9. Free-standing electronic character of monolayer MoS2 in van der Waals epitaxy

    Science.gov (United States)

    Kim, HoKwon; Dumcenco, Dumitru; Frégnaux, Mathieu; Benayad, Anass; Chen, Ming-Wei; Kung, Yen-Cheng; Kis, Andras; Renault, Olivier

    2016-08-01

    We have evaluated as-grown Mo S2 crystals, epitaxially grown on a monocrystalline sapphire by chemical vapor deposition (CVD), with direct electronic band-structure measurements by energy-filtered k -space photoelectron emission microscopy performed with a conventional laboratory vacuum ultraviolet He I light source under off-normal illumination. The valence states of the epitaxial Mo S2 were mapped in momentum space down to 7 eV below the Fermi level. Despite the high nucleation density within the imaged area, the CVD Mo S2 possesses an electronic structure similar to the free-standing monolayer Mo S2 single crystal, and it exhibits hole effective masses of 2.41 ±0.05 m0 , and 0.81 ±0.05 m0 , respectively, at Γ and K high-symmetry points that are consistent with the van der Waals epitaxial growth mechanism. This demonstrates the excellent ability of the Mo S2 CVD on sapphire to yield a highly aligned growth of well-stitched grains through epitaxial registry with a strongly preferred crystallographic orientation.

  10. Estimating the elastic properties of few-layer graphene from the free-standing indentation response.

    Science.gov (United States)

    Zhou, Lixin; Wang, Yugang; Cao, Guoxin

    2013-11-27

    Using molecular mechanics simulations, the elastic properties of multi-layer graphene (MLG) are investigated; this includes both the linear analysis based on the indentation load-displacement relationship and the nonlinear analysis based on the strain energy. The elastic properties of graphene layers in MLG are similar to each other and also quite close to those of monolayer graphene. The van der Waals (VDW) interaction between graphene layers (interlayer interaction) will create a difference between the indenter tip displacement and the deviation of MLG in indentation, which will cause an overestimation of the elastic modulus of MLG based on classic indentation analysis. This overestimation can be as high as 20%. In addition, the interlayer interaction will significantly affect the nonlinear elastic behavior of MLG in free-standing indentation. With an increase in the number of layers of MLG, the second-order elastic stiffness of MLG is very sensitive to the indentation loading range, and the third-order nonlinear elastic constant is significantly increased.

  11. Theory of activated glassy relaxation, mobility gradients, surface diffusion, and vitrification in free standing thin films.

    Science.gov (United States)

    Mirigian, Stephen; Schweizer, Kenneth S

    2015-12-28

    We have constructed a quantitative, force level, statistical mechanical theory for how confinement in free standing thin films introduces a spatial mobility gradient of the alpha relaxation time as a function of temperature, film thickness, and location in the film. The crucial idea is that relaxation speeds up due to the reduction of both near-surface barriers associated with the loss of neighbors in the local cage and the spatial cutoff and dynamical softening near the vapor interface of the spatially longer range collective elasticity cost for large amplitude hopping. These two effects are fundamentally coupled. Quantitative predictions are made for how an apparent glass temperature depends on the film thickness and experimental probe technique, the emergence of a two-step decay and mobile layers in time domain measurements, signatures of confinement in frequency-domain dielectric loss experiments, the dependence of film-averaged relaxation times and dynamic fragility on temperature and film thickness, surface diffusion, and the relationship between kinetic experiments and pseudo-thermodynamic measurements such as ellipsometry.

  12. Development of flexible, free-standing, thin films for additive manufacturing and localized energy generation

    Energy Technology Data Exchange (ETDEWEB)

    Clark, Billy; McCollum, Jena; Pantoya, Michelle L., E-mail: michelle.pantoya@ttu.edu [Mechanical Engineering Department, Texas Tech University, Lubbock TX 79409 (United States); Heaps, Ronald J.; Daniels, Michael A. [Idaho National Laboratory, PO Box 1625, Idaho Falls, ID 83415 (United States)

    2015-08-15

    Film energetics are becoming increasingly popular because a variety of technologies are driving a need for localized energy generation in a stable, safe and flexible form. Aluminum (Al) and molybdenum trioxide (MoO{sub 3}) composites were mixed into a silicon binder and extruded using a blade casting technique to form flexible free-standing films ideal for localized energy generation. Since this material can be extruded onto a surface it is well suited to additive manufacturing applications. This study examines the influence of 0-35% by mass potassium perchlorate (KClO{sub 4}) additive on the combustion behavior of these energetic films. Without KClO{sub 4} the film exhibits thermal instabilities that produce unsteady energy propagation upon reaction. All films were cast at a thickness of 1 mm with constant volume percent solids to ensure consistent rheological properties. The films were ignited and flame propagation was measured. The results show that as the mass percent KClO{sub 4} increased, the flame speed increased and peaked at 0.43 cm/s and 30 wt% KClO{sub 4}. Thermochemical equilibrium simulations show that the heat of combustion increases with increasing KClO{sub 4} concentration up to a maximum at 20 wt% when the heat of combustion plateaus, indicating that the increased chemical energy liberated by the additional KClO{sub 4} promotes stable energy propagation. Differential scanning calorimeter and thermogravimetric analysis show that the silicone binder participates as a fuel and reacts with KClO{sub 4} adding energy to the reaction and promoting propagation.

  13. Development of flexible, free-standing, thin films for additive manufacturing and localized energy generation

    Directory of Open Access Journals (Sweden)

    Billy Clark

    2015-08-01

    Full Text Available Film energetics are becoming increasingly popular because a variety of technologies are driving a need for localized energy generation in a stable, safe and flexible form. Aluminum (Al and molybdenum trioxide (MoO3 composites were mixed into a silicon binder and extruded using a blade casting technique to form flexible free-standing films ideal for localized energy generation. Since this material can be extruded onto a surface it is well suited to additive manufacturing applications. This study examines the influence of 0-35% by mass potassium perchlorate (KClO4 additive on the combustion behavior of these energetic films. Without KClO4 the film exhibits thermal instabilities that produce unsteady energy propagation upon reaction. All films were cast at a thickness of 1 mm with constant volume percent solids to ensure consistent rheological properties. The films were ignited and flame propagation was measured. The results show that as the mass percent KClO4 increased, the flame speed increased and peaked at 0.43 cm/s and 30 wt% KClO4. Thermochemical equilibrium simulations show that the heat of combustion increases with increasing KClO4 concentration up to a maximum at 20 wt% when the heat of combustion plateaus, indicating that the increased chemical energy liberated by the additional KClO4 promotes stable energy propagation. Differential scanning calorimeter and thermogravimetric analysis show that the silicone binder participates as a fuel and reacts with KClO4 adding energy to the reaction and promoting propagation.

  14. Ultrathin Polyamide Membranes Fabricated from Free-Standing Interfacial Polymerization: Synthesis, Modifications, and Post-treatment

    KAUST Repository

    Cui, Yue

    2016-12-21

    The thin film composite (TFC) membrane synthesized via interfacial polymerization is the workhorse of the prevalent membrane technologies such as nanofiltration (NF), reverse osmosis (RO), forward osmosis (FO), and pressure retarded osmosis (PRO) membranes. The polyamide selective layer usually possesses a high selectivity and permeability, making it the heart of this membrane technology. To further improve and understand its formation, with entirely excluding the effect of substrate, an ultrathin membrane which consists of only the polyamide selective layer has been fabricated via free-standing interfacial polymerization between M-phenylenediamine (MPD) and trimesoyl chloride (TMC) in this study. The influences of monomer concentration on polyamide layer formation is first examined. Different from previous studies which indicated that the variation of MPD concentration might affect the polyamide layer formation even when in excess, the MPD concentration when in excess does not affect membrane properties significantly, while increasing the TMC concentration gradually densifies the polyamide layer and enhances its transport resistance. Adding lithium bromide (LiBr) and sodium dodecyl sulfate (SDS) in MPD solutions is found to facilitate the reaction between the two phases and result in a significant improvement in water permeability. However, a high amount of additives leads to an augmentation in transport resistance. The N,N-dimethylformamide (DMF) treatment on the polyamide membrane shows pronounced improvements on water flux under FO tests and water permeability under RO tests without compromising reverse salt flux and salt rejection because the dense polyamide core stays intact. This study may offer a different perspective on membrane formation and intrinsic properties of the polyamide selective layer and provide useful insights for the development of next-generation TFC membranes.

  15. Seismic justification of free standing spent fuel storage racks: experimental versus computed behavior

    Energy Technology Data Exchange (ETDEWEB)

    Champomier, F.P. [FRAMATOME, 92 - Paris-La-Defence (France); Peron, J.Y. [ATEA, 44 - Carquefou (France)

    2001-07-01

    Most spent fuel storage racks now designed for nuclear power plants are of the free standing type. They consist in a series of independent modules of varying size (typically, 2 m long and wide and 5 m high) immersed in water but simply left standing on the bottom of the spent fuel storage pool. The ever increasing need for additional storage room leads power plants to wish to have compact modules positioned as close to each other as possible. The reduced clearance is essentially limited by the possible interaction of a module with its neighbors in case of a seismic event. In fact, during an earthquake, it is anticipated that each module may have a complex and different movement relative to the pool floor: sliding, uplifting, rocking may occur depending on various parameters related to module geometry and load and seismic excitation. Minimum clearance between modules is to be defined and justified. Two approaches are possible: each module may be demonstrated to stay wide from its neighbors or to impact them with no significant resulting damage. Though experimental work is sometimes possible, it certainly cannot be routinely or systematically envisaged. Thus, approaches to evaluation and justification basically rely on numerical simulation of the problem. Actually, the entire calculation scheme is often repeated a large number of times with varying parameters (seismic input in the three directions, friction coefficients, fuel loading characteristics, etc.) for additional treatment and confidence. The object of this paper is to provide some insight on the kind of information one can reasonably expect to obtain from such studies. (author)

  16. Free-Standing Undoped ZnO Microtubes with Rich and Stable Shallow Acceptors

    Science.gov (United States)

    Wang, Qiang; Yan, Yinzhou; Zeng, Yong; Lu, Yue; Chen, Liang; Jiang, Yijian

    2016-06-01

    Fabrication of reliable large-sized p-ZnO is a major challenge to realise ZnO-based electronic device applications. Here we report a novel technique to grow high-quality free-standing undoped acceptor-rich ZnO (A-ZnO) microtubes with dimensions of ~100 μm (in diameter) × 5 mm (in length) by optical vapour supersaturated precipitation. The A-ZnO exhibits long lifetimes (>1 year) against compensation/lattice-relaxation and the stable shallow acceptors with binding energy of ~127 meV are confirmed from Zn vacancies. The A-ZnO provides a possibility for a mimetic p-n homojunction diode with n+-ZnO:Sn. The high concentrations of holes in A-ZnO and electrons in n+-ZnO make the dual diffusion possible to form a depletion layer. The diode threshold voltage, turn-on voltage, reverse saturated current and reverse breakdown voltage are 0.72 V, 1.90 V, 15 V, respectively. The A-ZnO also demonstrates quenching-free donor-acceptor-pairs (DAP) emission located in 390-414 nm with temperature of 270-470 K. Combining the temperature-dependent DAP violet emission with native green emission, the visible luminescence of A-ZnO microtube can be modulated in a wide region of colour space across white light. The present work opens up new opportunities to achieve ZnO with rich and stable acceptors instead of p-ZnO for a variety of potential applications.

  17. Interfacial and topological effects on the glass transition in free-standing polystyrene films

    Science.gov (United States)

    Lyulin, Alexey V.; Balabaev, Nikolay K.; Baljon, Arlette R. C.; Mendoza, Gerardo; Frank, Curtis W.; Yoon, Do Y.

    2017-05-01

    United-atom molecular-dynamics computer simulations of atactic polystyrene (PS) were performed for the bulk and free-standing films of 2 nm-20 nm thickness, for both linear and cyclic polymers comprised of 80 monomers. Simulated volumetric glass-transition temperatures (Tg) show a strong dependence on the film thickness below 10 nm. The glass-transition temperature of linear PS is 13% lower than that of the bulk for 2.5 nm-thick films, as compared to less than 1% lower for 20 nm films. Our studies reveal that the fraction of the chain-end groups is larger in the interfacial layer with its outermost region approximately 1 nm below the surface than it is in the bulk. The enhanced population of the end groups is expected to result in a more mobile interfacial layer and the consequent dependence of Tg on the film thickness. In addition, the simulations show an enrichment of backbone aliphatic carbons and concomitant deficit of phenyl aromatic carbons in the interfacial film layer. This deficit would weaken the strong phenyl-phenyl aromatic (π -π ) interactions and, hence, lead to a lower film-averaged Tg in thin films, as compared to the bulk sample. To investigate the relative importance of the two possible mechanisms (increased chain ends at the surface or weakened π -π interactions in the interfacial region), the data for linear PS are compared with those for cyclic PS. For the cyclic PS, the reduction of the glass-transition temperature is also significant in thin films, albeit not as much as for linear PS. Moreover, the deficit of phenyl carbons in the film interface is comparable to that observed for linear PS. Therefore, chain-end effects alone cannot explain the observed pronounced Tg dependence on the thickness of thin PS films; the weakened phenyl-phenyl interactions in the interfacial region seems to be an important cause as well.

  18. Effect of working pressure and temperature on ZnO film deposited on free-standing diamond substrates

    Institute of Scientific and Technical Information of China (English)

    ZHAO Ping; XIA Yi-ben; WANG Lin-jun; LIU Jian-min; XU Run; PENG Hong-yan; SHI Wei-min

    2006-01-01

    The structure characteristic and electric performance of ZnO film deposited on nucleation side of free-standing diamond substrates under different heating temperatures (Th) of substrate and working pressures (p) were studied. The structure of the ZnO films tested by X-ray diffraction shows that ZnO film of high c-axis orientation is deposited on the nucleation side of free-standing diamond substrate which is extremely smooth when Th=250 ℃ and p=0.4 Pa. After annealing at 480 ℃ in N2 atmosphere,the SEM and the AFM analyses demonstrate that the c-axis orientation of ZnO film is obviously enhanced. The resistivity of ZnO films also increases up to 8×105 Ω·cm which is observed by I-V test.

  19. Direct Fabrication of Free-Standing MOF Superstructures with Desired Shapes by Micro-Confined Interfacial Synthesis.

    Science.gov (United States)

    Kim, Jin-Oh; Min, Kyoung-Ik; Noh, Hyunwoo; Kim, Dong-Hwi; Park, Soo-Young; Kim, Dong-Pyo

    2016-06-13

    Recently, metal-organic frameworks (MOFs) with multifunctional pore chemistry have been intensively investigated for positioning the desired morphology at specific locations onto substrates for manufacturing devices. Herein, we develop a micro-confined interfacial synthesis (MIS) approach for fabrication of a variety of free-standing MOF superstructures with desired shapes. This approach for engineering MOFs provides three key features: 1) in situ synthesis of various free-standing MOF superstructures with controlled compositions, shape, and thickness using a mold membrane; 2) adding magnetic functionality into MOF superstructures by loading with Fe3 O4 nanoparticles; 3) transferring the synthesized MOF superstructural array on to flat or curved surface of various substrates. The MIS route with versatile potential opens the door for a number of new perspectives in various applications.

  20. Few-layer MoS2-anchored graphene aerogel paper for free-standing electrode materials.

    Science.gov (United States)

    Lee, Wee Siang Vincent; Peng, Erwin; Loh, Tamie Ai Jia; Huang, Xiaolei; Xue, Jun Min

    2016-04-21

    To reduce the reliance on polymeric binders, conductive additives, and metallic current collectors during the electrode preparation process, as well as to assess the true performance of lithium ion battery (LIB) anodes, a free-standing electrode has to be meticulously designed. Graphene aerogel is a popular scaffolding material that has been widely used with embedded nanoparticles for application in LIB anodes. However, the current graphene aerogel/nanoparticle composite systems still involve decomposition into powder and the addition of additives during electrode preparation because of the thick aerogel structure. To further enhance the capacity of the system, MoS2 was anchored onto a graphene aerogel paper and the composite was used directly as an LIB anode. The resultant additive-free MoS2/graphene aerogel paper composite exhibited long cyclic performance with 101.1% retention after 700 cycles, which demonstrates the importance of free-standing electrodes in enhancing cyclic stability.

  1. Raw data for 'Tensile Strain Engineering of Germanium Micro-Disks on Free-Standing SiO2 Beams'.

    OpenAIRE

    Al-Attili, Abdelrahman

    2016-01-01

    This dataset contains the raw data for 'Tensile Strain Engineering of Germanium Micro-Disks on Free-Standing SiO2 Beams'. Summary of this dataset in the form of figures were published by the Japanese Journal of Applied Physics (JJAP), Special Issues of the International Conference on Solid-State Devices and Materials (SSDM) 2015, Sapporo, Japan.\\ud Copyright 2016 The Japan Society of Applied Physics.\\ud \\ud

  2. Few-layer MoS2-anchored graphene aerogel paper for free-standing electrode materials

    Science.gov (United States)

    Lee, Wee Siang Vincent; Peng, Erwin; Loh, Tamie Ai Jia; Huang, Xiaolei; Xue, Jun Min

    2016-04-01

    To reduce the reliance on polymeric binders, conductive additives, and metallic current collectors during the electrode preparation process, as well as to assess the true performance of lithium ion battery (LIB) anodes, a free-standing electrode has to be meticulously designed. Graphene aerogel is a popular scaffolding material that has been widely used with embedded nanoparticles for application in LIB anodes. However, the current graphene aerogel/nanoparticle composite systems still involve decomposition into powder and the addition of additives during electrode preparation because of the thick aerogel structure. To further enhance the capacity of the system, MoS2 was anchored onto a graphene aerogel paper and the composite was used directly as an LIB anode. The resultant additive-free MoS2/graphene aerogel paper composite exhibited long cyclic performance with 101.1% retention after 700 cycles, which demonstrates the importance of free-standing electrodes in enhancing cyclic stability.To reduce the reliance on polymeric binders, conductive additives, and metallic current collectors during the electrode preparation process, as well as to assess the true performance of lithium ion battery (LIB) anodes, a free-standing electrode has to be meticulously designed. Graphene aerogel is a popular scaffolding material that has been widely used with embedded nanoparticles for application in LIB anodes. However, the current graphene aerogel/nanoparticle composite systems still involve decomposition into powder and the addition of additives during electrode preparation because of the thick aerogel structure. To further enhance the capacity of the system, MoS2 was anchored onto a graphene aerogel paper and the composite was used directly as an LIB anode. The resultant additive-free MoS2/graphene aerogel paper composite exhibited long cyclic performance with 101.1% retention after 700 cycles, which demonstrates the importance of free-standing electrodes in enhancing cyclic

  3. Effects of ingestion by neotropical bats on germination parameters of native free-standing and strangler figs (Ficus sp., Moraceae).

    Science.gov (United States)

    Heer, Katrin; Albrecht, Larissa; Kalko, Elisabeth K V

    2010-06-01

    Fruit-eating animals can influence the germination success of seeds through transportation and handling. We experimentally tested the contribution of ingestion by the common fruit-eating bat, Artibeus jamaicensis (Phyllostomidae, Chiroptera), to the percentage and rate of seed germination of figs (Ficus, Moraceae), which are considered keystone species for many frugivores. We collected fruits from three species of native free-standing figs (subgenus Pharmacosycea: F. insipida, F. maxima and F. yoponensis) and three species of native strangler figs (subgenus Urostigma: F. nymphiifolia, F. obtusifolia and F. popenoei) on Barro Colorado Island, Panama. The germination success of seeds removed from fruit pulp either manually or by ingestion was very high (>92%), while seeds that were not removed from fruit pulp were destroyed by fast-growing fungi within a few days. The dynamics of seed germination were not influenced by ingestion, but differed between the two subgenera of figs. In free-standing figs, germination started significantly earlier (5.3 +/- 0.7 days) than in strangler figs (8.6 +/- 1.4 days). Furthermore, strangler seeds were covered with a sticky coating and their seedlings developed cotyledons faster than fine roots, in contrast to free-standing figs that showed the opposite pattern. Our results demonstrate that the germination of fig seeds is positively influenced by passage through the gut of A. jamaicensis. Furthermore, free-standing and strangler figs revealed differences in germination parameters that might be adaptive with respect to the suitability of microsites such as tree fall gaps or host trees for establishment.

  4. Fundamental Studies on Confinement Effects in Ionic Conduction and Inversion Layers in 2-D Single Crystal Free Standing Oxide Membranes

    Science.gov (United States)

    2014-02-14

    Scientific Progress Please see below Technology Transfer Number of graduating undergraduates who achieved a 3.5 GPA to 4.0 (4.0 max scale): Number of...2-dimensional free standing membrane with correlated oxides may also lead to new insights into mesoscopic electronic phenomena. Vanadium oxide ( VO2 ...well as for potential applications in switching devices. While studies have been conducted on thin films, hybrid layers of VO2 supported on other

  5. A Challenge Beyond Bottom Cells: Top-Illuminated Flexible Organic Solar Cells with Nanostructured Dielectric/Metal/Polymer (DMP) Films.

    Science.gov (United States)

    Ham, Juyoung; Dong, Wan Jae; Park, Jae Yong; Yoo, Chul Jong; Lee, Illhwan; Lee, Jong-Lam

    2015-07-15

    Top-illuminated flexible organic solar cells with a high power conversion efficiency (≈6.75%) are fabricated using a dielectric/metal/polymer (DMP) electrode. Employing a polymer layer (n = 1.49) makes it possible to show the high transmittance, which is insensitive to film thickness, and the excellent haze induced by well-ordered nanopatterns on the DMP electrode, leading to a 28% of enhancement in efficiency compared to bottom cells.

  6. Cleaved laser facets on free-standing InGaN LD membrane created by laser lift-off and structural characterisation of the membrane

    Science.gov (United States)

    Zilan, Li; Xiaodong, Hu; Zhixin, Qin; Tongjun, Yu; Ruijuan, Nie; Min, Lu; Qian, Ren; Bei, Zhang; Zhijian, Yang; Weihua, Chen; Zhizhong, Chen; Hua, Yang; Guoyi, Zhang

    2004-09-01

    Cleaved laser facets on free-standing InGaN laser diode membrane created by laser lift-off were fabricated and studied. Cleaved laser facets on GaN on sapphire have been compared with those on free-standing laser membrane. Atomic force microscopy and scanning electron microscopy results show that the cleaved laser facets on free-standing laser membrane are much smoother than those on sapphire. Transmission electron microscopy images show that no significant crystal quality degradation has been introduced during the laser lift-off process.

  7. Ultra-thin plasmonic color filters incorporating free-standing resonant membrane waveguides with high transmission efficiency

    Science.gov (United States)

    Wang, Jiaxing; Fan, Qingbin; Zhang, Si; Zhang, Zijie; Zhang, Hui; Liang, Yuzhang; Cao, Xun; Xu, Ting

    2017-01-01

    We propose an ultra-thin plasmonic color filtering device based on subwavelength metal grating engraved on a dielectric membrane waveguide without substrate. As experiments demonstrate, the fabricated free-standing plasmonic color filters have more than 70% transmission efficiency at different resonant wavelengths in the visible spectral region and are capable of generating arbitrary colors. Experimental results are in good agreement with the theoretical calculations. These artificial nanostructured color filtering devices may find potential applications in high resolution color imaging and sensing systems.

  8. Fluid-enabled significant enhancement and active tuning of magnetic resonances in free-standing plasmonic metamaterials.

    Science.gov (United States)

    Leong, Eunice Sok Ping; Liu, Yan Jun; Deng, Jie; Fong, Yih Ting; Zhang, Nan; Wu, Si Ji; Teng, Jing Hua

    2014-10-07

    We report significantly enhanced magnetic resonance by fluid infiltration in a free-standing metamaterial that consists of metal-dielectric-metal films on an ultrathin Si3N4 membrane patterned with etched through nanohole arrays. When different fluids are drop-casted on the structure, the magnetic resonance has high sensitivities of 282 nm per RIU in peak shift and 12% per RIU in peak intensity change, whereas the electric resonance has nearly no changes. This work shows a promising way of using fluids to actively tune the magnetic resonance of metamaterial structures by combining with micro/nano-fluidic technologies.

  9. Fabrication of free-standing, electrochemically active, and biocompatible graphene oxide-polyaniline and graphene-polyaniline hybrid papers.

    Science.gov (United States)

    Yan, Xingbin; Chen, Jiangtao; Yang, Jie; Xue, Qunji; Miele, Philippe

    2010-09-01

    In this work, we report a low-cost technique via simple rapid-mixture polymerization of aniline using graphene oxide (GO) and graphene papers as substrates, respectively, to fabricate free-standing, flexible GO-polyaniline (PANI) and graphene-PANI hybrid papers. The morphology and microstructure of the obtained papers were characterized by FESEM, FTIR, Raman, and XRD. As results, nanostructural PANI can be deposited on the surfaces of GO and graphene papers, forming thin, lightweight, and flexible paperlike hybrid papers. The hybrid papers display a remarkable combination of excellent electrochemical performances and biocompatibility, making the paperlike materials attractive for new kinds of applications in biosciences.

  10. One-step fabrication of free-standing flexible membranes reinforced with self-assembled arrays of carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Grilli, S.; Coppola, S.; Vespini, V.; Pagliarulo, V.; Ferraro, P. [Istituto Nazionale di Ottica (CNR) Via Campi Flegrei, 34 Pozzuoli, Napoli (Italy); Nasti, G. [Department of Chemical Materials and Production Engineering, University of Naples Federico II, PiazzaleTecchio 80 (Naples) (Italy); Institute for Polymers Composites and Biomaterials, National Council of Research of Italy, Via Campi Flegrei 34, 80078 Pozzuoli (Italy); Carfagna, C. [Department of Chemical Materials and Production Engineering, University of Naples Federico II, PiazzaleTecchio 80 (Naples) (Italy)

    2014-10-13

    Here, we report on a single step approach for fabricating free-standing polymer membranes reinforced with arrayed self-assembled carbon nanotubes (CNTs). The CNTs are self-assembled spontaneously by electrode-free DC dielectrophoresis based on surface charge templates. The electrical charge template is generated through the pyroelectric effect onto periodically poled lithium niobate ferroelectric crystals. A thermal stimulus enables simultaneously the self-assembly of the CNTs and the cross-linking of the host polymer. Examples of thin polydimethylsiloxane membranes reinforced with CNT patterns are shown.

  11. Facile synthesis of free-standing Pd-based nanomembranes with enhanced catalytic performance for methanol/ethanol oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Haoxi [State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, Jilin (China); Graduate University of the Chinese Academy of Sciences, Beijing 100039 (China); Li, Haijuan; Zhai, Yujuan; Xu, Xiaolong; Jin, Yongdong [State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, Jilin (China)

    2012-03-22

    Macroscopic free-standing Pd and Pd/Pt bimetallic monolayer nanomembranes (Pd- and Pd/Pt-FNMs) derived from the spontaneous self-assembly of the as-produced Pd NPs and Pd/Pt bimetallic NPs at the water-air interface within 15 min are fabricated, respectively. The one-step method allows the growth of high-quality Pd-based FNMs with well-defined monolayer morphology, which exhibit significantly higher electrocatalytic activity for methanol/ethanol oxidation than commercial catalysts. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  12. X-ray diffraction investigations of adherent and free standing TiN coatings deposited by magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Valvoda, V.; Kuzel, R. Jr.; Dobiasova, L.; Cerny, R. (Charles Univ., Prague (Czechoslovakia). Faculty of Mathematics and Physics); Poulek, V.; Musil, J. (Czechoslovak Academy of Sciences, Prague (Czechoslovakia). Inst. of Physics)

    1990-06-01

    TiN coatings deposited on steel substrates at different biases and temperatures, and with different nitrogen contents, were studied by conventional X-ray powder diffractometry. The diffraction peaks were separated by profile fitting. In adherent films different kinds of texture and a large anisotropy of lattice parameters (a(hhh) < a(h00) < a(hh0)) were detected. In corresponding free-standing films lower average values of lattice parameters were found and their anisotropy decreased considerably. The microstrain determined from X-ray line broadening remained unchanged, which proves its inelastic nature owing to the lattice defects.

  13. SnO2-graphene nanocomposite free-standing film as anode in lithium-ion batteries

    Science.gov (United States)

    Choi, Eunmi; Kim, Daeun; Lee, Ilbok; Chae, Su Jin; Kim, Areum; Pyo, Sung Gyu; Yoon, Songhun

    2015-09-01

    SnO2-reduced graphene oxide nanocomposite in the form of a free-standing film was prepared by simple chemical synthesis. The homogeneous and compact formation of the nanocomposite of SnO2 and reduced graphene oxide was confirmed by various analysis methods. When incorporated as anode in lithium-ion batteries, a high capacity (503 mAh g-1) and very stable cycle life were observed. These favorable properties probably arise from the efficient relaxation of high mechanical stress by the reduced graphene-oxide layers during the lithiation-delithiation process within SnO2. [Figure not available: see fulltext.

  14. Monolithic integration of a lithium niobate microresonator with a free-standing waveguide using femtosecond laser assisted ion beam writing

    Science.gov (United States)

    Fang, Zhiwei; Xu, Yingxin; Wang, Min; Qiao, Lingling; Lin, Jintian; Fang, Wei; Cheng, Ya

    2017-01-01

    We demonstrated integrating a high quality factor lithium niobate microdisk resonator with a free-standing membrane waveguide. Our technique is based on femtosecond laser direct writing which produces the pre-structure, followed by focused ion beam milling which reduces the surface roughness of sidewall of the fabricated structure to nanometer scale. Efficient light coupling between the integrated waveguide and microdisk was achieved, and the quality factor of the microresonator was measured as high as 1.67 × 105. PMID:28358135

  15. Stability, structural and electronic properties of benzene molecule adsorbed on free standing Au layer

    Energy Technology Data Exchange (ETDEWEB)

    Katoch, Neha, E-mail: nehakatoch2@gmail.com; Kapoor, Pooja; Sharma, Munish; Ahluwalia, P. K. [Physics Department, Himachal Pradesh University, Shimla, Himachal Pradesh, India 171005 (India); Kumar, Ashok [Center for Physical Sciences, School of Basic and Applied Sciences, Central University of Punjab, Bathinda, India, 151001 (India)

    2016-05-23

    We report stability and electronic properties of benzene molecule adsorbed on the Au atomic layer within the framework of density function theory (DFT). Horizontal configuration of benzene on the top site of Au monolayer prefers energetically over other studied configurations. On the adsorption of benzene, the ballistic conductance of Au monolayer is found to decrease from 4G{sub 0} to 2G{sub 0} suggesting its applications for the fabrications of organic sensor devices based on the Au atomic layers.

  16. Importance of energy and angular resolutions in top-hat electrostatic analysers for solar wind proton measurements

    Science.gov (United States)

    De Marco, R.; Marcucci, M. F.; Bruno, R.; D'Amicis, R.; Servidio, S.; Valentini, F.; Lavraud, B.; Louarn, P.; Salatti, M.

    2016-08-01

    We use a numerical code which reproduces the angular/energy response of a typical top-hat electrostatic analyser starting from solar wind proton velocity distribution functions (VDFs) generated by numerical simulations. The simulations are based on the Hybrid Vlasov-Maxwell numerical algorithm which integrates the Vlasov equation for the ion distribution function, while the electrons are treated as a fluid. A virtual satellite launched through the simulation box measures the particle VDFs. Such VDFs are moved from the simulation Cartesian grid to energy-angular coordinates to mimic the response of a real sensor in the solar wind. Different energy-angular resolutions of the analyser are investigated in order to understand the influence of the phase-space resolution in existing and upcoming space missions, with regards to determining the key parameters of plasma dynamics.

  17. Piezoelectric potential gated field-effect transistor based on a free-standing ZnO wire.

    Science.gov (United States)

    Fei, Peng; Yeh, Ping-Hung; Zhou, Jun; Xu, Sheng; Gao, Yifan; Song, Jinhui; Gu, Yudong; Huang, Yanyi; Wang, Zhong Lin

    2009-10-01

    We report an external force triggered field-effect transistor based on a free-standing piezoelectric fine wire (PFW). The device consists of an Ag source electrode and an Au drain electrode at two ends of a ZnO PFW, which were separated by an insulating polydimethylsiloxane (PDMS) thin layer. The working principle of the sensor is proposed based on the piezoelectric potential gating effect. Once subjected to a mechanical impact, the bent ZnO PFW cantilever creates a piezoelectric potential distribution across it width at its root and simultaneously produces a local reverse depletion layer with much higher donor concentration than normal, which can dramatically change the current flowing from the source electrode to drain electrode when the device is under a fixed voltage bias. Due to the free-standing structure of the sensor device, it has a prompt response time less than 20 ms and quite high and stable sensitivity of 2%/microN. The effect from contact resistance has been ruled out.

  18. Free-Standing Thin Webs of Activated Carbon Nanofibers by Electrospinning for Rechargeable Li-O2 Batteries.

    Science.gov (United States)

    Nie, Hongjiao; Xu, Chi; Zhou, Wei; Wu, Baoshan; Li, Xianfeng; Liu, Tao; Zhang, Huamin

    2016-01-27

    Free-standing activated carbon nanofibers (ACNF) were prepared through electrospinning combining with CO2 activation and then used for nonaqueous Li-O2 battery cathodes. As-prepared ACNF based cathode was loosely packed with carbon nanofibers complicatedly overlapped. Owing to some micrometer-sized pores between individual nanofibers, relatively high permeability of O2 across the cathode becomes feasible. Meanwhile, the mesopores introduced by CO2 activation act as additional nucleation sites for Li2O2 formation, leading to an increase in the density of Li2O2 particles along with a size decrease of the individual particles, and therefore, flake-like Li2O2 are preferentially formed. In addition, the free-standing structure of ACNF cathode eliminates the side reactions about PVDF. As a result, the Li-O2 batteries with ACNF cathodes showed increased discharge capacities, reduced overpotentials, and longer cycle life in the case of full discharge and charge operation. This provides a novel pathway for the design of cathodes for Li-O2 battery.

  19. Free-standing and flexible LiMnTiO4/carbon nanotube cathodes for high performance lithium ion batteries

    Science.gov (United States)

    Bao, Yinhua; Zhang, Xingyu; Zhang, Xu; Yang, Le; Zhang, Xinyi; Chen, Haosen; Yang, Meng; Fang, Daining

    2016-07-01

    A flexible, free-standing, and light-weight LiMnTiO4/MWCNT electrode has been prepared by vacuum filtration method for the first time. The as-prepared flexible LiMnTiO4/MWCNT electrode possesses a three-dimensional braiding structure in which LiMnTiO4 particles are well embedded in the twining CNT networks. The novel LiMnTiO4/MWCNT electrodes show tensile strength of 1.34 MPa and 2.04 MPa, when the percentages of MWCNTs reach to 30% and 50%, respectively. This novel flexible electrode exhibits a superior electrochemical property, especially at rate capability and cycling stability. The LiMnTiO4/MWCNT electrode can deliver capacity of 161 mAh g-1 (86.4% retention) after 50 cycles at 0.5C rate. Since the high conductivity from MWCNT networks, the LiMnTiO4/MWCNT electrode can still maintain a capacity of 77 mAh g-1 at 5C rate, which is much higher than that of the conventional electrode fabricated by slurry casting method on Al foil. The features of free-standing, light-weight, and excellent electrochemical performance indicate the potential of using the LiMnTiO4/MWCNT cathode in new-generation flexible lithium ion batteries.

  20. Plasmons in a free-standing nanorod with a two-dimensional parabolic quantum well caused bv surface states

    Institute of Scientific and Technical Information of China (English)

    Song Ya-Feng; Lü Yan-Wu; Wen Wei; Liu Xiang-Lin; Yang Shao-Yan; Zhu Qin-Sheng; Wang Zhan-Guo

    2012-01-01

    The collective charge density excitations in a free-standing nanorod with a two-dimensional parabolic quantum well are investigated within the framework of Bohm-Pine's random-phase approximation in the two-subband model.The new simplified analytical expressions of the Coulomb interaction matrix elements and dielectric functions are derived and numerically discussed.In addition,the electron density and temperature dependences of dispersion features are also investigated.We find that in the two-dimensional parabolic quantum well,the intrasubband upper branch is coupled with the intersubband mode,which is quite different from other quasi-one-dimensional systems like a cylindrical quantum wire with an infinite rectangular potential.In addition,we also find that higher temperature results in the intersubband mode(with an energy of 12 meV(~3 THz))becoming totally damped,which agrees well with the experimental results of Raman scattering in the literature.These interesting properties may provide useful references to the design of free-standing nanorod based devices.

  1. Residual stress and buckling patterns of free-standing yttria-stabilized-zirconia membranes fabricated by pulsed laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Evans, A.; Prestat, M.; Toelke, R.; Schlupp, M.V.F.; Gauckler, L.J. [ETH Zurich, Nonmetallic Inorganic Materials, Zurich (Switzerland); Safa, Y.; Hocker, T. [ZHAW Winterthur, Institute of Computational Physics, Winterthur (Switzerland); Courbat, J.; Briand, D.; Rooij, N.F. de [Ecole Polytechnique Federale de Lausanne (EPFL), Institute of Microengineering, Neuchatel (Switzerland); Courty, D. [ETH Zurich, Laboratory for Nanometallurgy, Zurich (Switzerland)

    2012-08-15

    The residual stress and buckling patterns of free-standing 8 mol.% yttria-stabilized-zirconia (8YSZ) membranes prepared by pulsed laser deposition and microfabrication techniques on silicon substrates are investigated by wafer curvature, light microscopy, white light interferometry, and nanoindentation. The 300 nm thin 8YSZ membranes (390 {mu}m x 390 {mu}m) deposited at 25 C are almost flat after free-etching, whereas deposition at 700 C yields strongly buckled membranes with a compressive stress of -1,100 {+-} 150 MPa and an out-of-plane-displacement of 6.5 {mu}m. These latter membranes are mechanically stable during thermal cycling up to 500 C. Numerical simulations of the buckling shape using the Rayleigh-Ritz-method and a Young's modulus of 200 GPa are in good agreement with the experimental data. The simulated buckling patterns are used to extract the local stress distribution within the free-standing membrane which consists of tensile and compressive stress regions that are below the failure stresses. This is important regarding the application in, e.g., microsolid oxide fuel cell membranes which must be thermomechanically stable during microfabrication and device operation. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  2. Physical Aging of Thin and Ultrathin Free-Standing Polymer Films: Effect of Stress and Reduced Glass Transitions

    Science.gov (United States)

    Pye, Justin; Roth, Connie

    2014-03-01

    While great effort has been made in elucidating the effect of confinement on the glass transition (Tg) in polymers, considerably less work has been done on physical aging. Starting with supported films, we have previously shown that the reduced physical aging rates in ultrathin polystyrene (PS) films can be linked to the reduced Tg near the free surface [Macromolecules 2010, 43, 8296]. We then showed that high molecular weight (MW) free-standing PS films have two reduced Tgs suggesting that two separate mechanisms are acting simultaneously to propagate enhanced mobility at the free surface deeper into the film [PRL 2011, 107, 235701]. To help determine the mechanisms of these two reduced Tgs, we performed physical aging measurements on these high MW free-standing PS films. For thick films (220-1800 nm) in which there are no Tg reductions, we find that the physical aging rate depends strongly on stress caused by thermal expansion mismatch between film and support. This stress, applied to the films as they are quenched into the glassy state, can nearly double the physical aging rate when changing the frame material from polycarbonate to silicon [Macromolecules 2013, DOI:10.1021/ma401872u]. Finally, ultrathin high MW PS films held at a temperature between the two Tgs do exhibit physical aging, indicating that at least some of the film is glassy between these two transitions.

  3. Magnetic confinement effects on the particle escape from the loop top in stochastic acceleration models for solar flares.

    Science.gov (United States)

    Effenberger, F.; Petrosian, V.

    2015-12-01

    Stochastic acceleration scenarios are among the most promising candidates to explain the high energies attained by particles in solar flares. Recent progress in the determination of fundamental acceleration parameters using novel techniques for the inversion of high resolution RHESSI hard X-ray spectra allows to determine non-thermal electron spectra at the loop top and foot points of a flare loop (Chen & Petrosian 2014). One outcome of this work is that the trapping and escape of the electrons is governed by wave particle scatterings and convergence of magnetic lines of force. Here, we present a computational study of the transport and escape processes of particles in the acceleration region. We employ a Fokker-Planck model, which includes pitch-angle scattering and magnetic mirroring in a non-uniform magnetic field. This allows to test analytical approximations for the particle escape times in the loop top region, which are helpful to constrain the key particle acceleration parameters. New perspectives will be given on how the insights gained from the analysis of the particle confinement will enable subsequent studies of a broader class of solar flares.

  4. Unresolved fine-scale structure in solar coronal loop-tops

    CERN Document Server

    Scullion, Eamon; Wedemeyer, Sven; Antolin, Patrick

    2014-01-01

    New and advanced space-based observing facilities continue to lower the resolution limit and detect solar coronal loops in greater detail. We continue to discover even finer sub-structures within coronal loop cross sections, in order to understand the nature of the solar corona. Here, we push this lower limit further to search for the finest coronal loop sub-structures, through taking advantage of the resolving power of the Swedish 1- m Solar Telescope (SST) / CRisp Imaging Spectro-Polarimeter (CRISP), together with co-observations from the Solar Dynamics Observatory (SDO) / Atmospheric Image Assembly (AIA). High resolution imaging of the chromospheric H-alpha 656.28 nm spectral line core and wings can, under certain circumstances, allow one to deduce the topology of the local magnetic environment of the solar atmosphere where its observed. Here, we study post-flare coronal loops, which become filled with evaporated chromosphere that rapidly condenses into chromospheric clumps of plasma (detectable in H-alpha...

  5. The application of highly doped single-layer graphene as the top electrodes of semitransparent organic solar cells.

    Science.gov (United States)

    Liu, Zhike; Li, Jinhua; Sun, Zhen-Hua; Tai, Guoan; Lau, Shu-Ping; Yan, Feng

    2012-01-24

    A single-layer graphene film with high conductance and transparency was realized by effective chemical doping. The conductance of single-layer graphene was increased for more than 400% when it was doped with Au nanoparticles and poly(3,4-ethylenedioxythiophene): poly(styrene sulfonic acid). Then semitransparent organic solar cells based on poly(3-hexylthiophene) (P3HT) and phenyl-C61-butyric acid methyl ester (PCBM) were fabricated with single-layer graphene and indium tin oxide (ITO) as the top and bottom electrodes, respectively. The performance of the devices was optimized by tuning the active layer thickness and doping the single-layer graphene electrodes. The maximum efficiency of 2.7% was observed in the devices with the area of 20 mm(2) illuminated from graphene electrode under the AM1.5 solar simulator. It is notable that all of the devices showed higher efficiency from the graphene than ITO side, which was attributed to the better transmittance of the graphene electrodes. In addition, the influence of the active area of the organic solar cell on its photovoltaic performance was studied. We found that, when the active areas increased from 6 to 50 mm(2), the power conversion efficiencies decreased from 3% to 2.3% because of the increased series resistances and the decreased edge effect of the devices.

  6. Modelling loop-top X-ray source and reconnection outflows in solar flares with intense lasers

    Science.gov (United States)

    Zhong, Jiayong; Li, Yutong; Wang, Xiaogang; Wang, Jiaqi; Dong, Quanli; Xiao, Chijie; Wang, Shoujun; Liu, Xun; Zhang, Lei; An, Lin; Wang, Feilu; Zhu, Jianqiang; Gu, Yuan; He, Xiantu; Zhao, Gang; Zhang, Jie

    2010-12-01

    Magnetic reconnection is a process by which oppositely directed magnetic field lines passing through a plasma undergo dramatic rearrangement, converting magnetic potential into kinetic energy and heat. It is believed to play an important role in many plasma phenomena including solar flares, star formation and other astrophysical events, laser-driven plasma jets, and fusion plasma instabilities. Because of the large differences of scale between laboratory and astrophysical plasmas, it is often difficult to extrapolate the reconnection phenomena studied in one environment to those observed in the other. In some cases, however, scaling laws do permit reliable connections to made, such as the experimental simulation of interactions between the solar wind and the Earth's magnetosphere. Here we report well-scaled laboratory experiments that reproduce loop-top-like X-ray source emission by reconnection outflows interacting with a solid target. Our experiments exploit the mega-gauss-scale magnetic field generated by interaction of a high-intensity laser with a plasma to reconstruct a magnetic reconnection topology similar to that which occurs in solar flares. We also identify the separatrix and diffusion regions associated with reconnection in which ions become decoupled from electrons on a scale of the ion inertial length.

  7. High performance 380-nm ultraviolet light-emitting-diodes with 3% efficiency droop by using free-standing GaN substrate manufacturing from GaAs substrate

    Science.gov (United States)

    Shieh, Chen-Yu; Tsai, Ming-Ta; Li, Zhen-Yu; Kuo, Hao-Chung; Chang, Jenq-Yang; Chi, Gou-Chung; Lee, Wei-I.

    2014-01-01

    We investigated the influence of free-standing GaN (FS-GaN) substrates on the performance of ultraviolet light-emitting-diodes (UV-LEDs) grown on top by atmospheric pressure metal-organic chemical vapor deposition. High-resolution double-crystal x-ray diffraction (HRDCXD) analysis demonstrated high-order satellite peaks and clear fringes between them for UV-LEDs grown on the FS-GaN substrate, from which the interface roughness was estimated. In addition, the full width at half maximum of the HRDCXD rocking curve in the (0002) and the (10 1¯ 2) reflections were reduced to below 90 arc sec. The Raman results indicated that the GaN-based epilayer of strain free was grown. Additionally, the effect of the FS-GaN substrate on the crystal quality of the UV-LEDs was examined in detail by transmission electron microscopy (TEM). The TEM characterizations revealed no defects and V-pits were found in the scanned area. Based on the results mentioned above, the light output power of UV-LEDs on the FS-GaN substrate can be enhanced drastically by 80% and 90% at 20 and 100 mA, respectively. Furthermore, an ultralow efficiency degradation of about 3% can be obtained for the UV-LEDs on the FS-GaN substrate at a high injection current. The use of an FS-GaN substrate is suggested to be effective for improving the emission efficiency and droop of UV-LEDs grown thereon.

  8. In Situ Activating Ubiquitous Rust towards Low-Cost, Efficient, Free-Standing, and Recoverable Oxygen Evolution Electrodes.

    Science.gov (United States)

    Zhong, Haixia; Wang, Jun; Meng, Fanlu; Zhang, Xinbo

    2016-08-16

    Developing effective ways to recycle rusted stainless steel and to promote the sluggish oxygen evolution reaction (OER), associated with water splitting and metal-air batteries, is important for a resource-sustainable and environment-friendly society. Herein, we propose a strategy to enable rusted stainless steel plate to be used as an abundant and low-cost OER catalyst, wherein a hydrothermal combined in situ electrochemical oxidation-reduction cycle (EORC) method is developed to mimic and expedite the corrosion process, and thus activate stainless steel into free-standing OER electrodes. Benefiting from the plentiful electrolyte-accessible Fe/(Ni) oxyhydroxides, high conductivity and mechanical stability, this electrode exhibits remarkable OER performances including low overpotential, fast kinetics, and long-term durability. The slight degradation in current after long-term use can be repaired immediately in situ by an EORC.

  9. Multifunctional Free-Standing Gel Polymer Electrolyte with Carbon Nanofiber Interlayers for High-Performance Lithium-Sulfur Batteries.

    Science.gov (United States)

    Choi, Sinho; Song, Jianjun; Wang, Chengyin; Park, Soojin; Wang, Guoxiu

    2017-07-04

    Free-standing trimethylolpropane ethoxylate triacrylate gel polymer electrolyte is synthesized by a chemical cross-linking process and used as an electrolyte and separator membrane in lithium-sulfur batteries. The cross linked gel polymer electrolyte also exhibited a stable geometric size retention of 95 % at the high temperature of 130 °C. The as-prepared gel polymer electrolyte membrane with carbon nanofibers interlayer can effectively prevent polysulfide dissolution and shuttle effect, leading to significantly enhanced electrochemical properties, including high capacity and cycling stability, with an enhanced specific capacity of 790 mA h g(-1) after 100 cycles. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Surface tension and disjoining pressure of free-standing smectic films above the bulk smectic-A-isotropic transition temperature

    Energy Technology Data Exchange (ETDEWEB)

    Zakharov, A. V., E-mail: avz0911@yahoo.com [Saint Petersburg Institute for Machine Sciences, The Russian Academy of Sciences, Saint Petersburg 199178 (Russian Federation); Śliwa, Izabela, E-mail: izasliwa@ifmpan.poznan.pl [Institute of Molecular Physics, Polish Academy of Sciences, Smoluchowskiego 17, 60-179 Poznan (Poland)

    2014-03-28

    We have carried out a numerical study of both the structural and thermodynamic properties of free-standing smectic films for the case of enhanced pair interaction in the bounding layers. Calculations, based upon the extended McMillan's mean-field theory with anisotropic forces, show that the layer-thinning transitions are characterized by abrupt drops to lower values, both for a disjoining pressure and a fluctuation-induced long-range interaction between the smectic film surfaces, and then continues to increase with a larger positive slope. Reasonable agreement between the theoretically predicted and the experimentally obtained data on the surface tension of the partially fluorinated 5-n-alkyl-2-(4-n-(perfluoroalkyl-metheleneoxy)phenyl) film has been obtained.

  11. A flexible, gigahertz, and free-standing thin film piezoelectric MEMS resonator with high figure of merit

    Science.gov (United States)

    Jiang, Yuan; Zhang, Menglun; Duan, Xuexin; Zhang, Hao; Pang, Wei

    2017-07-01

    In this paper, a 2.6 GHz air-gap type thin film piezoelectric MEMS resonator was fabricated on a flexible polyethylene terephthalate film. A fabrication process combining transfer printing and hot-embossing was adopted to form a free-standing structure. The flexible radio frequency MEMS resonator possesses a quality factor of 946 and an effective coupling coefficient of 5.10%, and retains its high performance at a substrate bending radius of 1 cm. The achieved performance is comparable to that of conventional resonators on rigid silicon wafers. Our demonstration provides a viable approach to realizing universal MEMS devices on flexible polymer substrates, which is of great significance for building future fully integrated and multi-functional wireless flexible electronic systems.

  12. SBA-15 mesoporous silica free-standing thin films containing copper ions bounded via propyl phosphonate units - preparation and characterization

    Science.gov (United States)

    Laskowski, Lukasz; Laskowska, Magdalena; Jelonkiewicz, Jerzy; Dulski, Mateusz; Wojtyniak, Marcin; Fitta, Magdalena; Balanda, Maria

    2016-09-01

    The SBA-15 silica thin films containing copper ions anchored inside channels via propyl phosphonate groups are investigated. Such materials were prepared in the form of thin films, with hexagonally arranged pores, laying rectilinear to the substrate surface. However, in the case of our thin films, their free standing form allowed for additional research possibilities, that are not obtainable for typical thin films on a substrate. The structural properties of the samples were investigated by X-ray reflectometry, atomic force microscopy (AFM) and transmission electron microscopy (TEM). The molecular structure was examined by Raman spectroscopy supported by numerical simulations. Magnetic measurements (SQUID magnetometry and EPR spectroscopy) showed weak antiferromagnetic interactions between active units inside silica channels. Consequently, the pores arrangement was determined and the process of copper ions anchoring by propyl phosphonate groups was verified in unambiguous way. Moreover, the type of interactions between magnetic atoms was determined.

  13. Template free synthesis of free-standing silver nanowhisker and nanocrown superlattice by interfering femtosecond laser irradiation

    Science.gov (United States)

    Nakata, Yoshiki; Miyanaga, Noriaki; Momoo, Kazuma; Hiromoto, Takuya

    2014-09-01

    We report the fabrication and control of a nanostructure superlattice of silver using a solid-liquid-solid (SLS) mechanism induced on a silver thin film by interfering femtosecond laser irradiation. An interference pattern induces fluid flows of silver, which is followed by freezing of a free-standing nanowhisker, nanobump, or nanocrown superlattice fixed on a substrate. The smallest curvature radius of the nanowhisker’s apex was 4 nm, which is smaller than one-fifth of the silver nanorods fabricated by chemosynthesis. The SLS process is a superior alternative to sequential bottom-up processes involving bottom-up synthesis of nanorods, purification, alignment or self-assembling, stabilization, and preservation.

  14. Tolerance of GaAs as an original substrate for HVPE growth of free standing GaN

    Science.gov (United States)

    Suzuki, Mio; Sato, T.; Suemasu, T.; Hasegawa, F.

    2004-09-01

    In order to investigate possibility of thick GaN growth on a GaAs substrate by halide vapar phase epitaxy (HVPE), GaN was grown on GaAs(111)/Ti wafer with Ti deposited by E-gun. It was found that surface treatment of the GaAs substrate by HF solution deteriorated greatly the tolerence of GaAs and that Ti can protected GaAs from erosion by NH3. By depositing Ti on GaAs(111)A surface, a millor-like GaN layer could be grown at 1000 °C for 1 hour without serious deterioration of the original GaAs substrate. By increasing the growth rate, a thick free standing GaN will be obtained with GaAs as an original substrate in near future.

  15. The electronic structure of quasi-free-standing germanene on monolayer MX (M = Ga, In; X = S, Se, Te).

    Science.gov (United States)

    Ni, Zeyuan; Minamitani, Emi; Ando, Yasunobu; Watanabe, Satoshi

    2015-07-15

    For the first time by using the ab initio density functional theory, the stability and electronic structures of germanene on monolayer GaS, GaSe, GaTe and InSe have been investigated. Germanene preserves its buckled-honeycomb structure on all the studied substrates similar to the free-standing case. Moreover, germanene stays neutral and preserves its Dirac-cone-like band structure on monolayer GaTe and InSe. In these two cases, a bandgap of 0.14-0.16 eV opens at the Dirac point of germanene, while the effective masses remain as small as 0.05-0.06 times the free-electron mass. The estimated carrier mobility is up to 2.2 × 10(5) cm(2) V(-1) s(-1). These features show that monolayer GaTe and InSe are promising as substrates for germanene devices.

  16. NanoFIBrication of a two-dimensional phononic crystal in a free standing membrane.

    Energy Technology Data Exchange (ETDEWEB)

    Leseman, Zayd C. (University of New Mexico, Albuquerque, NM); Goettler, Drew F. (University of New Mexico, Albuquerque, NM); Su, Mehmet F. (University of New Mexico, Albuquerque, NM); El-Kady, Ihab Fathy; Olsson, Roy H., III

    2010-06-01

    A two-dimensional phononic crystal (PnC) that can operate in the GHz range is created in a freestanding silicon substrate using NanoFIBrication (using a focused ion beam (FIB) to fabricate nanostructures). First, a simple cubic 6.75 x 6.75 ?m array of vias with 150 nm spacing is generated. After patterning the vias, they are backfilled with void-free tungsten scatterers. Each via has a diameter of 48 nm. Numerical calculations predict this 2D PnC will generate a band gap near 22 GHz. A protective layer of chromium on top of the thin (100 nm) silicon membrane confines the surface damage to the chromium, which can be removed at a later time. Inspection of the underside of the membrane shows the vias flaring out at the exit, which we are dubbing the 'trumpet effect'. The trumpet effect is explained by modeling the lateral damage in a freestanding membrane.

  17. Spin relaxation in Si nanoclusters embedded in free-standing SiGe nanocolumns

    Science.gov (United States)

    Stepina, N. P.; Zinovieva, A. F.; Dvurechenskii, A. V.; Noda, Shuichi; Molla, Md. Zaman; Samukawa, Seiji

    2017-05-01

    Separated nanocolumns (NCs) with embedded Si nanoclusters were prepared using the top-down technique that combines a bio-template and the defect-free neutral beam etching of Si0.75Ge0.25/Si/Si0.75Ge0.25 double-quantum-well layers. The electron spin resonance (ESR) was studied in the dark and under illumination for the structures with different lateral sizes of NCs. For the structure with a NC diameter in the range of 20-25 nm, the ESR signal is characterized by the isotropic line width. The spatial separation of nanoclusters results in the suppression of the Dyakonov-Perel mechanism of spin relaxation. A decrease in the NC diameter down to 13-14 nm leads to electron localization under the bottom of NCs, making the orientation dependence of the ESR line width anisotropic. Illumination results in the increase in spin lifetimes in both the types of NC structures, relocating the electrons to the center of NCs in the narrow NC structure, and making electron localization stronger in the thick NCs.

  18. F-formation detection: individuating free-standing conversational groups in images.

    Directory of Open Access Journals (Sweden)

    Francesco Setti

    Full Text Available Detection of groups of interacting people is a very interesting and useful task in many modern technologies, with application fields spanning from video-surveillance to social robotics. In this paper we first furnish a rigorous definition of group considering the background of the social sciences: this allows us to specify many kinds of group, so far neglected in the Computer Vision literature. On top of this taxonomy we present a detailed state of the art on the group detection algorithms. Then, as a main contribution, we present a brand new method for the automatic detection of groups in still images, which is based on a graph-cuts framework for clustering individuals; in particular, we are able to codify in a computational sense the sociological definition of F-formation, that is very useful to encode a group having only proxemic information: position and orientation of people. We call the proposed method Graph-Cuts for F-formation (GCFF. We show how GCFF definitely outperforms all the state of the art methods in terms of different accuracy measures (some of them are brand new, demonstrating also a strong robustness to noise and versatility in recognizing groups of various cardinality.

  19. F-formation detection: individuating free-standing conversational groups in images.

    Science.gov (United States)

    Setti, Francesco; Russell, Chris; Bassetti, Chiara; Cristani, Marco

    2015-01-01

    Detection of groups of interacting people is a very interesting and useful task in many modern technologies, with application fields spanning from video-surveillance to social robotics. In this paper we first furnish a rigorous definition of group considering the background of the social sciences: this allows us to specify many kinds of group, so far neglected in the Computer Vision literature. On top of this taxonomy we present a detailed state of the art on the group detection algorithms. Then, as a main contribution, we present a brand new method for the automatic detection of groups in still images, which is based on a graph-cuts framework for clustering individuals; in particular, we are able to codify in a computational sense the sociological definition of F-formation, that is very useful to encode a group having only proxemic information: position and orientation of people. We call the proposed method Graph-Cuts for F-formation (GCFF). We show how GCFF definitely outperforms all the state of the art methods in terms of different accuracy measures (some of them are brand new), demonstrating also a strong robustness to noise and versatility in recognizing groups of various cardinality.

  20. Light-Weight Free-Standing Carbon Nanotube-Silicon Films for Anodes of Lithium Ion Batteries

    KAUST Repository

    Cui, Li-Feng

    2010-07-27

    Silicon is an attractive alloy-type anode material because of its highest known capacity (4200 mAh/g). However, lithium insertion into and extraction from silicon are accompanied by a huge volume change, up to 300%, which induces a strong strain on silicon and causes pulverization and rapid capacity fading due to the loss of the electrical contact between part of silicon and current collector. Si nanostructures such as nanowires, which are chemically and electrically bonded to the current collector, can overcome the pulverization problem, however, the heavy metal current collectors in these systems are larger in weight than Si active material. Herein we report a novel anode structure free of heavy metal current collectors by integrating a flexible, conductive carbon nanotube (CNT) network into a Si anode. The composite film is free-standing and has a structure similar to the steel bar reinforced concrete, where the infiltrated CNT network functions as both mechanical support and electrical conductor and Si as a high capacity anode material for Li-ion battery. Such free-standing film has a low sheet resistance of ∼30 Ohm/sq. It shows a high specific charge storage capacity (∼2000 mAh/g) and a good cycling life, superior to pure sputtered-on silicon films with similar thicknesses. Scanning electron micrographs show that Si is still connected by the CNT network even when small breaking or cracks appear in the film after cycling. The film can also "ripple up" to release the strain of a large volume change during lithium intercalation. The conductive composite film can function as both anode active material and current collector. It offers ∼10 times improvement in specific capacity compared with widely used graphite/copper anode sheets. © 2010 American Chemical Society.

  1. 18.4%-Efficient Heterojunction Si Solar Cells Using Optimized ITO/Top Electrode.

    Science.gov (United States)

    Kim, Namwoo; Um, Han-Don; Choi, Inwoo; Kim, Ka-Hyun; Seo, Kwanyong

    2016-05-11

    We optimize the thickness of a transparent conducting oxide (TCO) layer, and apply a microscale mesh-pattern metal electrode for high-efficiency a-Si/c-Si heterojunction solar cells. A solar cell equipped with the proposed microgrid metal electrode demonstrates a high short-circuit current density (JSC) of 40.1 mA/cm(2), and achieves a high efficiency of 18.4% with an open-circuit voltage (VOC) of 618 mV and a fill factor (FF) of 74.1% as result of the shortened carrier path length and the decreased electrode area of the microgrid metal electrode. Furthermore, by optimizing the process sequence for electrode formation, we are able to effectively restore the reduction in VOC that occurs during the microgrid metal electrode formation process. This work is expected to become a fundamental study that can effectively improve current loss in a-Si/c-Si heterojunction solar cells through the optimization of transparent and metal electrodes.

  2. Bending in HVPE GaN free-standing films: effects of laser lift-off, polishing and high-pressure annealing

    Energy Technology Data Exchange (ETDEWEB)

    Paskova, T. [Department of Physics and Measurement Technology, Linkoeping University, 581 83 Linkoeping (Sweden); Institute of Solid State Physics, University of Bremen, 28359 Bremen (Germany); Darakchieva, V.; Paskov, P.P.; Monemar, B. [Department of Physics and Measurement Technology, Linkoeping University, 581 83 Linkoeping (Sweden); Bukowski, M.; Suski, T. [High Pressure Research Center, Unipress, Polish Academy of Sciences, 01-142 Warsaw (Poland); Ashkenov, N.; Schubert, M. [Fakultaet fuer Physik and Geowissenschaften, Universitaet Leipzig, 04103 Leipzig (Germany); Hommel, D. [Institute of Solid State Physics, University of Bremen, 28359 Bremen (Germany)

    2006-06-15

    We have studied the effects of laser lift-off and polishing processes on the bending of free-standing HVPE grown GaN thick films. Their structural characteristics were accessed by reciprocal space mapping and lattice parameters measurements as well as by Raman scattering and photoluminescence. The in-plane strain difference between the two faces was found to have determining effect on the bending of the free-standing films. Removing the high-defect-density near-interface region either by melting caused by laser lift-off, or by polishing, or by point defects dissociation caused by high-pressure annealing was found to lead to flattening of the strain distribution along the film thickness and a significant reduction of the bending of the free-standing films. (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  3. Effects of Anodic Buffer Layer in Top-Illuminated Organic Solar Cell with Silver Electrodes

    Directory of Open Access Journals (Sweden)

    Tien-Lung Chiu

    2013-01-01

    Full Text Available An efficient ITO-free top-illuminated organic photovoltaic (TOPV based on small molecular planar heterojunction was achieved by spinning a buffer layer of poly(3,4-ethylenedioxythiophene:poly(styrenesulfonate (PEDOT:PSS, on the Ag-AgOx anode. The PEDOT:PSS thin film separates the active layer far from the Ag anode to prevent metal quenching and redistributes the strong internal optical field toward dissociated interface. The thickness and morphology of this anodic buffer layer are the key factors in determining device performances. The uniform buffer layer contributes a large short-circuit current and open-circuit voltage, benefiting the final power conversion efficiency (PCE. The TOPV device with an optimal PEDOT:PSS thickness of about 30 nm on Ag-AgOx anode exhibits the maximum PCE of 1.49%. It appreciates a 1.37-fold enhancement in PCE over that of TOPV device without buffer layer.

  4. Efficient recyclable organic solar cells on cellulose nanocrystal substrates with a conducting polymer top electrode deposited by film-transfer lamination

    Science.gov (United States)

    Yinhua Zhou; Talha M. Khan; Jen-Chieh Liu; Canek Fuentes-Hernandez; Jae Won Shim; Ehsan Najafabadi; Jeffrey P. Youngblood; Robert J. Moon; Bernard Kippelen

    2014-01-01

    We report on efficient solar cells on recyclable cellulose nanocrystal (CNC) substrates with a new device structure wherein polyethylenimine-modified Ag is used as the bottom electron-collecting electrode and high-conductivity poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT:PSS, PH1000) is used as the semitransparent top holecollecting electrode. The...

  5. Free-standing few-layered graphene oxide films: selective, steady and lasting permeation of organic molecules with adjustable speeds

    Science.gov (United States)

    Huang, Tao; An, Qi; Luan, Xinglong; Zhang, Qian; Zhang, Yihe

    2016-01-01

    A variety of small molecules with diameters around 1 nm possess a range of functions, such as antibiotic, antimicrobic, anticoagulant, pesticidal and chemotherapy effects, making these molecules especially useful in various applications ranging from medical treatment to environmental microbiological control. However, the long-term steady delivery (release or permeation) of these small molecules with adjustable and controllable speeds has remained an especially challenging task. In this study, we prepared covalently cross-linked free-standing few-layered GO films using a layer-by-layer technique in combination with photochemical cross-linkages, and achieved a controlled release of positively charged, negatively charged, and zwitterionic small molecules with adjustable and controllable speeds. The steady delivery of the small molecule lasted up to 9 days. Other functionalities, such as graphene-enhanced Raman spectra and electrochemical properties that could also be integrated or employed in delivery systems, were also studied for our films. We expect the special molecular delivery properties of our films to lead to new possibilities in drug/fertilizer delivery and environmental microbiological control applications.A variety of small molecules with diameters around 1 nm possess a range of functions, such as antibiotic, antimicrobic, anticoagulant, pesticidal and chemotherapy effects, making these molecules especially useful in various applications ranging from medical treatment to environmental microbiological control. However, the long-term steady delivery (release or permeation) of these small molecules with adjustable and controllable speeds has remained an especially challenging task. In this study, we prepared covalently cross-linked free-standing few-layered GO films using a layer-by-layer technique in combination with photochemical cross-linkages, and achieved a controlled release of positively charged, negatively charged, and zwitterionic small molecules with

  6. Fabrication and characterization of free-standing, high-line-density transmission gratings for the vacuum UV to soft X-ray range

    NARCIS (Netherlands)

    Goh, S.J.; Bastiaens, H.J.M.; Vratzov, B.; Huang, Q.; Bijkerk, F.; Boller, K-J.

    2015-01-01

    We present state-of-the-art high resolution transmission gratings, applicable for spectroscopy in the vacuum ultraviolet (VUV) and the soft X-ray (SRX) wavelength range, fabricated with a novel process using ultraviolet based nano imprint lithography (UV-NIL). Free-standing, high-line-density gratin

  7. Fast and safe fabrication of a free-standing chitosan/alginate nanomembrane to promote stem cell delivery and wound healing

    Science.gov (United States)

    Kong, Yi; Xu, Rui; Darabi, Mohammad Ali; Zhong, Wen; Luo, Gaoxing; Xing, Malcolm MQ; Wu, Jun

    2016-01-01

    Polymeric ultrathin membranes that are compatible with cells offer tremendous advantages for tissue engineering. In this article, we report a free-standing nanomembrane that was developed using a layer-by-layer self-assembly technique with a safe and sacrificial substrate method. After ionization, two oppositely charged polyelectrolytes, alginate and chitosan, were alternately deposited on a substrate of a solidified gelatin block to form an ultrathin nanomembrane. The space between the two adjacent layers was ∼200 nm. The thickness of the nanomembrane was proportional to the number of layers. The temperature-sensitive gelatin gel served as a sacrificial template at 37°C. The free-standing nanomembrane promoted bone marrow stem cell adhesion and proliferation. Fluorescence-activated cell sorting was used to analyze green-fluorescent-protein-positive mesenchymal stem cells from the wounds, which showed a significantly high survival and proliferation from the nanomembrane when cells were transplanted to mouse dorsal skin that had a full-thickness burn. The bone-marrow-stem-cell-loaded nanomembrane also accelerated wound contraction and epidermalization. Therefore, this methodology provides a fast and facile approach to construct free-standing ultrathin scaffolds for tissue engineering. The biocompatibility and free-standing nature of the fabricated nanomembrane may be particularly useful for stem cell delivery and wound healing. PMID:27354789

  8. An Analysis of Physician Productivity and Self-Sustaining Revenue Generation in a Free-Standing Emergency Department Medical Scribe Model

    Directory of Open Access Journals (Sweden)

    Brody Dawkins

    2015-01-01

    Full Text Available Objectives. A free-standing emergency department (FSED is a facility that provides comprehensive emergency medical care similar to a traditional emergency department but is not attached to a hospital campus. Medical scribes are increasingly likely to work in free-standing emergency departments. The purpose of this study was to retrospectively investigate the benefits of a scribe program in an FSED. Methods. A retrospective, Institutional Review Board-approved analysis from December 1, 2013, to February 1, 2015, of free-standing emergency department medical data was extracted to determine if scribed charts resulted in increased revenue and improved throughput. Results. When scribes are present in the FSED there is a small, but statistically significant, decrease in time from patient arrival to provider by 2.74 minutes. Scribed charts collected $4.69 more per chart and resulted in an increase in productivity. Incremental cost effectiveness ratios resulted in proven cost-utility with a net-positive effect. Conclusion. While there are some gains in terms of operational metrics and provider productivity with the addition of scribes to a free-standing emergency department, there is a net-positive financial impact of scribes. Implementing a scribe program at a FSED is cost-effective and justified from both an operational and a financial analysis.

  9. Comparison of CDE data in phacoemulsification between an open hospital-based ambulatory surgical center and a free-standing ambulatory surgical center

    Directory of Open Access Journals (Sweden)

    Ming Chen

    2010-11-01

    Full Text Available Ming Chen1, Mindy Chen21University of Hawaii, Honolulu, HI, USA; 2University of California, Irvine, CA, USAAbstract: Mean CDE (cumulative dissipated energy values were compared for an open hospital-based surgical center and a free-standing surgical center. The same model of phacoemulsifier (Alcon Infiniti Ozil was used. Mean CDE values showed that surgeons (individual private practice at the free-standing surgical center were more efficient than surgeons (individual private practice at the open hospital-based surgical center (mean CDE at the hospital-based surgical center 18.96 seconds [SD = 12.51]; mean CDE at the free-standing surgical center 13.2 seconds [SD = 9.5]. CDE can be used to monitor the efficiency of a cataract surgeon and surgical center in phacoemulsification. The CDE value may be used by institutions as one of the indicators for quality control and audit in phacoemulsification.Keywords: CDE (cumulative dissipated energy, open hospital-based ambulatory surgical center, free-standing surgical center, phacoemulsification 

  10. Ultrathin Two-Dimensional Free-Standing Sandwiched NiFe/C for High-Efficiency Oxygen Evolution Reaction.

    Science.gov (United States)

    Feng, Yangyang; Zhang, Huijuan; Zhang, Yan; Li, Xiao; Wang, Yu

    2015-05-06

    A NiFe-based compound is considered one of the most promising candidates for the highest oxygen evolution reaction (OER) electrocatalytic activities among all nonprecious metal-based electrocatalysts. In this report, a unique catalyst of free-standing sandwiched NiFe nanoparticles encapsulated by graphene sheets is first devised and fabricated. In this method, we use low-cost, sustainable, and environmentally friendly glucose as a carbon source, ultrathin Fe-doped Ni(OH)2 nanosheets as a precursor, and a sacrificial template. This special nanoarchitecture with a conductive network around active catalysts can accelerate electron transfer and prevent NiFe nanoparticles from aggregation and peeling off during long-time electrochemical reactions, thereby exhibiting an excellent OER activity and stability in basic solutions. In this work, our sandwiched catalyst presents well activities of a low onset of ∼1.44 V (vs RHE) and Tafel slope of ∼30 mV/decade in 1 M KOH at a scan rate of 5 mV/s.

  11. Nonlinear optical properties of free standing films of PbS quantum dots in the nonresonant femtosecond regime

    Science.gov (United States)

    Kurian, Pushpa Ann; Vijayan, C.; Nag, Amit; Goswami, Debabrata

    2013-01-01

    Devices based on optical technology for high speed communication networks require materials with large nonlinear optical response in the ultrafast regime. Nonlinear optical materials have also attracted wide attention as potential candidates for the protection of optical sensors and eyes while handling lasers. Optical limiters have a constant transmittance at low input influence and a decrease in transmittance at higher fluences and are based on a variety of mechanisms such as nonlinear refraction, nonlinear scattering, multiphoton absorption and free carrier absorption. As we go from bulk to nanosized materials especially in the strong quantum confinement regime where radius of the nanoparticle is less than the bulk exciton Bohr radius, the optical nonlinearity is enhanced due to quantum confinement effect. This paper is on the ultrafast nonresonant nonlinearity in free standing films of PbS quantum dots stabilized in a synthetic glue matrix by a simple chemical route which provides flexibility of processing in a variety of physical forms. Optical absorption spectrum shows significant blue shift from the bulk absorption onset indicating strong quantum confinement. PbS quantumdots of mean size 3.3nm are characterized by X-ray diffraction and transmission electron microscopy. The mechanism of nonlinear absorption giving rise to optical limiting is probed using open z-scan technique with laser pulses of 150 fs pulse duration at 780 nm and the results are presented in the nonresonant femtosecond regime. Irradiance dependence on nonlinear absorption are discussed. PMID:24143059

  12. The growth of heteroepitaxial CuInSe2 on free-standing N-polar GaN

    Directory of Open Access Journals (Sweden)

    Cheng-Hung Shih

    2014-12-01

    Full Text Available We report that chalcopyrite CuInSe2 thin films were grown on free-standing N-polar GaN (000 1 ̄ by molecular beam epitaxy. X-ray diffraction showed that the CuInSe2 thin film was grown in (112 orientation, and its peak of rocking curve with full width at half maximum of about 897.8 arc-sec indicated the epitaxial growth of CuInSe2 (112 film on N-polar GaN. Microstructure analysis of the CuInSe2  showed that the large lattice mismatch (28.5% between CuInSe2  and GaN is accommodated by domain matching, and no interface reaction occurs between CuInSe2 and GaN. Our experimental results show that GaN is stable for the epitaxial growth of CuInSe2 thin film, which exhibits a promising potential for optoelectronic applications.

  13. Layer-by-layer assembled PVA/Laponite multilayer free-standing films and their mechanical and thermal properties

    Science.gov (United States)

    Umasankar Patro, T.; Wagner, H. Daniel

    2011-11-01

    Structural arrangements of nanoplatelets in a polymer matrix play an important role in determining their properties. In the present study, multilayered composite films of poly(vinyl alcohol) (PVA) with Laponite clay are assembled by layer-by-layer (LBL) deposition. The LBL films are found to be hydrated, flexible and transparent. A facile and solvent-free method—by depositing self-assembled monolayers (SMA) of a functional silane on substrates—is demonstrated for preparing free-standing LBL films. Evolution of nanostructures in LBL films is correlated with thermal and mechanical properties. A well-dispersed solvent-cast PVA/Laponite composite film is also studied for comparison. We found that structurally ordered LBL films with an intercalated nanoclay system exhibits tensile strength, modulus and toughness, which are significantly higher than that of the conventional nanocomposites with well-dispersed clay particles and that of pure PVA. This indicates that clay platelets are oriented in the applied stress direction, leading to efficient interfacial stress transfer. In addition, various grades of composite LBL films are prepared by chemical crosslinking and their mechanical properties are assessed. On account of these excellent properties, the LBL films may find potential use as optical and structural elements, and as humidity sensors.

  14. The Influence of Electrode Microstructure on the Performance of Free-Standing Cathode for Aprotic Lithium-Oxygen Battery

    Science.gov (United States)

    Shen, Chen; Wen, Zhaoyin; Wang, Fan; Wu, Xiangwei; Chen, Chunhua

    2016-10-01

    Free-standing NiCo2O4@Ni cathodes for aprotic lithium-oxygen batteries were synthesized through a simple hydrothermal process followed by heat treatment in the air. The morphology of the NiCo2O4 deposit changed from nanosheet to nanowire with the increase of hydrothermal time. Further observation revealed that the nanosheet/nanowire NiCo2O4 were assembled by nanoparticles with a size of 10-20 nm. The directional assembly of the nanoparticles were not affected by the reaction time. The influence of catalyst microstructure on the electrochemical performance of Li-O2 batteries was studied. The results of battery tests in pure oxygen indicate that the cathode material with a high specific surface area, large pore volume and broad pore size distribution can facilitate the discharge reaction, leading to an improved cell performance. As a result, the cathode based on the NiCo2O4 nanowire array delivered a specific discharge capacity of 1682 mAh g-1 at 30 mA g-1 and a stable cyclability of 50 cycles with a capacity limitation of 500 mAh g-1.

  15. Structures, thermal stability, and melting behaviors of free-standing pentagonal multi-shell Pd-Pt nanowires

    Science.gov (United States)

    Cheng, D.; Hou, M.

    2010-04-01

    Classical molecular dynamics and Metropolis Monte Carlo simulations were carried out to investigate the thermal stability and melting behaviors of free-standing Pd-Pt bimetallic nanowires (NWs) with pentagonal multi-shell-type (PMS-type) structure in the whole composition range. Equilibrium configurations at 100 K are predicted in the semi-grand canonical ensemble. Pd-Pt PMS-type NWs are stable with a multishell structure of alternating Pd and Pt compositions and Pd segregating systematically to the surface. On thermal heating, an interesting composition-dependent structural transformation from the PMS-type to face-centred-cubic (FCC) by overcoming a high energy barrier is observed for Pd-Pt bimetallic NWs before the melting. Consequently, the system energy is decreased. The FCC structure is found more stable than PMS-type over the whole range of composition. The melting of Pd-Pt bimetallic NWs is also studied. It is found to start at the edges, then propagate over the whole surface, and next to the interior. It occurs in a composition-dependent range of temperature.

  16. Free-standing nitrogen-doped graphene paper as electrodes for high-performance lithium/dissolved polysulfide batteries.

    Science.gov (United States)

    Han, Kai; Shen, Jingmei; Hao, Shiqiang; Ye, Hongqi; Wolverton, Christopher; Kung, Mayfair C; Kung, Harold H

    2014-09-01

    Free-standing N-doped graphene papers (NGP), generated by pyrolysis of polydiallyldimethylammonium chloride, were successfully used as binder-free electrodes for the state-of-the-art Li/polysulfide-catholyte batteries. They exhibited high specific capacities of approximately 1000 mA h g(-1) (based on S) after 100 cycles and coulombic efficiencies great than 98%, significantly better than undoped graphene paper (GP). These NGP were characterized with XRD, X-ray photoelectron spectroscopy, thermogravimetric analysis, AFM, electron microscopy, and Raman and impedance spectroscopy before and after cycling. Spectroscopic evidence suggested stronger binding of sulfide to NGP relative to GP, and modelling results from DFT calculation, substantiated with experimental data, indicated that pyrrolic and pyridinic N atoms interacted more strongly with Li polysulfides than quaternary N atoms. Thus, more favorable partition of polysulfides between the electrode and the electrolyte and the corresponding effect on the morphology of the passivation layer were the causes of the beneficial effect of N doping. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Electrical and mechanical controlling of the kinetic and magnetic properties of hydrogen atoms on free-standing silicene

    Science.gov (United States)

    Podsiadły-Paszkowska, Agata; Krawiec, Mariusz

    2016-07-01

    Effects of strain, charge doping and external electric field on kinetic and magnetic properties of hydrogen atoms on a free-standing silicene layer are investigated by first-principles density functional theory. It was found that the charge doping and strain are the most effective ways of changing the hydrogen-silicene binding energy, but they can only raise its value. The perpendicular external electric field can also lower it albeit in a narrower range. The strain has also the strongest impact on diffusion processes, and the diffusion barrier can be modified up to 50% of its unstrained value. The adsorption of hydrogen atoms results in a locally antiferromagnetic ground state with the effective exchange constant of approximately 1 eV. The system can easily be driven into a nonmagnetic phase by the charge doping and strain. The obtained results are very promising in view of the silicene functionalization and potential applications of silicene in fields of modern nanoelectronics and spintronics.

  18. Heteroepitaxy of Ge on Si(001) with pits and windows transferred from free-standing porous alumina mask

    Science.gov (United States)

    Huangfu, Yourui; Zhan, Wenbo; Hong, Xia; Fang, Xu; Ding, Guqiao; Ye, Hui

    2013-05-01

    This paper reports the use of ultrathin free-standing porous alumina membrane (PAM) in pattern transferring for selective epitaxial growth (SEG) of Ge dots and films on Si. PAM, as a large-scale, controllable and lithography-free mask, can transfer nanopatterns onto Si without introducing any contaminants. High-density Ge dots are achievable with Ge adatoms confined in Si pits transferred from PAM. High-quality Ge films can also be grown on Si substrates through SiO2 nano-windows. In this work, 80 and 60 nm pore sizes of PAM were transferred to 70, 50 and 20 nm windows for comparison. For the former two sizes, over-etching of Si beneath every SiO2 window forms epi-seeds to improve intermixing of Ge-Si. No threading dislocations can be observed emanating from the epi-seeds due to the decreased lattice mismatch. An innovative shadow-etching technique utilizing the aspect ratio of PAM further decreased the lateral dimension of patterns from 60 to 20 nm. Cross-sectional transmission electron microscopy images show that the selective epitaxial Ge films grown from a 20 nm-width interface are defect free, which is attributed to the exponential decay of strain energy as well as Ge-Si intermixing.

  19. Translational diffusion across a free-standing smectic film above the bulk smectic-A-isotropic transition temperature.

    Science.gov (United States)

    Śliwa, Izabela; Zakharov, A V

    2017-01-01

    Calculations of translational self-diffusion coefficient in free-standing smectic films during a series of layer-thinning transitions as the temperature is raised above the bulk smectic-A-isotropic transition have been carried out. A molecular model based upon the random walk theory is applied for calculating the translational diffusion coefficient (TDC) D_{∥} across the smectic film both in the bulk of the film, as well as in the vicinity of the bounding surfaces. Calculations of D_{∥} require the set of the orientational and translational order parameters (OPs) which have been obtained by using the extended McMillan approach with anisotropic forces. The effect of E on the orientational and translational OPs, as well as on the TDC of smectic films has been investigated. A reasonable agreement between the theoretically predicted and the experimentally obtained data on the TDC in the bulk of the partially fluorinated H10F5MOPP film has been obtained. We also found, in agreement with the experimentally observed behavior of D_{∥}(N)(N=25,13,11,10), that the translational diffusion coefficient in the bulk of the film gradually increases as the film thickness N is decreased.

  20. Nonlinear optical properties of free standing films of PbS quantum dots in the nonresonant femtosecond regime.

    Science.gov (United States)

    Kurian, Pushpa Ann; Vijayan, C; Nag, Amit; Goswami, Debabrata

    2007-09-17

    Devices based on optical technology for high speed communication networks require materials with large nonlinear optical response in the ultrafast regime. Nonlinear optical materials have also attracted wide attention as potential candidates for the protection of optical sensors and eyes while handling lasers. Optical limiters have a constant transmittance at low input influence and a decrease in transmittance at higher fluences and are based on a variety of mechanisms such as nonlinear refraction, nonlinear scattering, multiphoton absorption and free carrier absorption. As we go from bulk to nanosized materials especially in the strong quantum confinement regime where radius of the nanoparticle is less than the bulk exciton Bohr radius, the optical nonlinearity is enhanced due to quantum confinement effect. This paper is on the ultrafast nonresonant nonlinearity in free standing films of PbS quantum dots stabilized in a synthetic glue matrix by a simple chemical route which provides flexibility of processing in a variety of physical forms. Optical absorption spectrum shows significant blue shift from the bulk absorption onset indicating strong quantum confinement. PbS quantumdots of mean size 3.3nm are characterized by X-ray diffraction and transmission electron microscopy. The mechanism of nonlinear absorption giving rise to optical limiting is probed using open z-scan technique with laser pulses of 150 fs pulse duration at 780 nm and the results are presented in the nonresonant femtosecond regime. Irradiance dependence on nonlinear absorption are discussed.

  1. Telekommunikatsioonifirmade TOP

    Index Scriptorium Estoniae

    2005-01-01

    Telekommunikatsioonifirmade TOP 28; Käibe TOP 15; Käibe kasvu TOP15; Kasumi TOP 15; Kasumi kasvu TOP 15; Rentaabluse TOP 10; Omakapitali tootlikkuse TOP 10; Telekommunikatsioonifirmade üld- ja finantsandmed

  2. Exploring the raft-hypothesis by probing planar bilayer patches of free-standing giant vesicles at nanoscale resolution, with and without Na,K-ATPase

    DEFF Research Database (Denmark)

    Bhartia, Tripta; Cornelius, Flemming; Ipsen, J. H.

    2016-01-01

    The structure of functional lipid domains (rafts) in biological membranes has for long time been unresolved due to their small length scales and transient nature. These cooperative properties of the lipid bilayer matrix are modelled by free-standing giant unilammellar vesicles (GUVs) with well-ch...... interfacial activity and cluster in lo/ld micro-emulsion droplets. Some perspectives for the application of the techniques and the understanding of the nature of raft domains are outlined....

  3. Fast and safe fabrication of a free-standing chitosan/alginate nanomembrane to promote stem cell delivery and wound healing

    Directory of Open Access Journals (Sweden)

    Kong Y

    2016-06-01

    Full Text Available Yi Kong,1,2,* Rui Xu,1,* Mohammad Ali Darabi,2 Wen Zhong,3 Gaoxing Luo,1 Malcolm MQ Xing,1,2 Jun Wu1 1Institute of Burn Research, Southwest Hospital, State Key Laboratory of Trauma, Burns, and Combined Injury, Chongqing Key Laboratory for Diseases Proteomics, Third Military Medical University, Chongqing, People’s Republic of China; 2Department of Mechanical Engineering, Biochemistry and Medical Genetics, Children’s Hospital Research Institute of Manitoba, 3Department of Biosystem Engineering, University of Manitoba, Winnipeg, MB, Canada *These authors contributed equally to this work Abstract: Polymeric ultrathin membranes that are compatible with cells offer tremendous advantages for tissue engineering. In this article, we report a free-standing nanomembrane that was developed using a layer-by-layer self-assembly technique with a safe and sacrificial substrate method. After ionization, two oppositely charged polyelectrolytes, alginate and chitosan, were alternately deposited on a substrate of a solidified gelatin block to form an ultrathin nanomembrane. The space between the two adjacent layers was ~200 nm. The thickness of the nanomembrane was proportional to the number of layers. The temperature-sensitive gelatin gel served as a sacrificial template at 37°C. The free-standing nanomembrane promoted bone marrow stem cell adhesion and proliferation. Fluorescence-activated cell sorting was used to analyze green-fluorescent-protein-positive mesenchymal stem cells from the wounds, which showed a significantly high survival and proliferation from the nanomembrane when cells were transplanted to mouse dorsal skin that had a full-thickness burn. The bone-marrow-stem-cell-loaded nanomembrane also accelerated wound contraction and epidermalization. Therefore, this methodology provides a fast and facile approach to construct free-standing ultrathin scaffolds for tissue engineering. The biocompatibility and free-standing nature of the fabricated

  4. Growth of free-standing bulk wurtzite AlxGa1-xN layers by molecular beam epitaxy using a highly efficient RF plasma source

    Science.gov (United States)

    Novikov, S. V.; Staddon, C. R.; Sahonta, S.-L.; Oliver, R. A.; Humphreys, C. J.; Foxon, C. T.

    2016-12-01

    The recent development of group III nitrides allows researchers world-wide to consider AlGaN based light emitting diodes as a possible new alternative deep ultra-violet light source for surface decontamination and water purification. In this paper we will describe our recent results on plasma-assisted molecular beam epitaxy (PA-MBE) growth of free-standing wurtzite AlxGa1-xN bulk crystals using the latest model of Riber's highly efficient nitrogen RF plasma source. We have achieved AlGaN growth rates up to 3 μm/h. Wurtzite AlxGa1-xN layers with thicknesses up to 100 μm were successfully grown by PA-MBE on 2-inch and 3-inch GaAs (111)B substrates. After growth the GaAs was subsequently removed using a chemical etch to achieve free-standing AlxGa1-xN wafers. Free-standing bulk AlxGa1-xN wafers with thicknesses in the range 30-100 μm may be used as substrates for further growth of AlxGa1-xN-based structures and devices. High Resolution Scanning Transmission Electron Microscopy (HR-STEM) and Convergent Beam Electron Diffraction (CBED) were employed for detailed structural analysis of AlGaN/GaAs (111)B interface and allowed us to determine the N-polarity of AlGaN layers grown on GaAs (111)B substrates. The novel, high efficiency RF plasma source allowed us to achieve free-standing AlxGa1-xN layers in a single day's growth, making this a commercially viable process.

  5. Vertically Free-Standing Ordered Pb(Zr0.52Ti0.48)O3 Nanocup Arrays by Template-Assisted Ion Beam Etching

    Science.gov (United States)

    Zhang, Xiaoyan; Tang, Dan; Huang, Kangrong; Hu, Die; Zhang, Fengyuan; Gao, Xingsen; Lu, Xubing; Zhou, Guofu; Zhang, Zhang; Liu, Junming

    2016-04-01

    In this report, vertically free-standing lead zirconate titanate Pb(Zr0.52Ti0.48)O3 (PZT) nanocup arrays with good ordering and high density (1.3 × 1010 cm-2) were demonstrated. By a template-assisted ion beam etching (IBE) strategy, the PZT formed in the pore-through anodic aluminum oxide (AAO) membrane on the Pt/Si substrate was with a cup-like nanostructure. The mean diameter and height of the PZT nanocups (NCs) was about 80 and 100 nm, respectively, and the wall thickness of NCs was about 20 nm with a hole depth of about 80 nm. Uppermost, the nanocup structure with low aspect ratio realized vertically free-standing arrays when losing the mechanical support from templates, avoiding the collapse or bundling when compared to the typical nanotube arrays. X-ray diffraction (XRD) and Raman spectrum revealed that the as-prepared PZT NCs were in a perovskite phase. By the vertical piezoresponse force microscopy (VPFM) measurements, the vertically free-standing ordered ferroelectric PZT NCs showed well-defined ring-like piezoresponse phase and hysteresis loops, which indicated that the high-density PZT nanocup arrays could have potential applications in ultra-high non-volatile ferroelectric memories (NV-FRAM) or other nanoelectronic devices.

  6. Going beyond the classical amphiphilicity paradigm: the self-assembly of completely hydrophobic polymers into free-standing sheets and hollow nanostructures in solvents of variable quality.

    Science.gov (United States)

    Huang, Huanting; Liao, Yin; Bu, Weifeng; Wang, Wenjie; Sun, Jing Zhi

    2016-06-14

    Self-assembly is well-known to occur in amphiphiles, and the totally hydrophobic ones are never reported to self-assemble. In this work we report for the first time that the latter can self-assemble into free-standing sheets and hollow spheres in toluene/methanol mixed solvents by modulating the solvent quality. The homopolymers studied in this work are polystyrene (PS), polyphenylacetylene (PPA), and poly(3-hexyl thiophene) (P3HT), representing polymers with different rigidity. All the three form a homogenous solution in toluene, but self-assembly occurs in the toluene/methanol mixed solvents. Micrometer sized free-standing sheets were formed for PS, PPA, and P3HT at methanol volume fractions being 43%, 50%, and 67%, respectively, and hollow spheres were observed for PPA at higher methanol fractions of 75 and 90%. Under the latter solvent conditions, PS forms solid spheres, yet ill-defined aggregates and free-standing sheets coexist in the case of P3HT. This non-solvent induced self-assembly was explained by a delicate balance of two "opposing forces": van der Waals attractive and entropic repulsive forces generated between the segments of these homopolymers within a single chain, between two chains, and among more chains in the solvents of worsened quality.

  7. Free-Standing T-Nb₂O₅/Graphene Composite Papers with Ultrahigh Gravimetric/Volumetric Capacitance for Li-Ion Intercalation Pseudocapacitor.

    Science.gov (United States)

    Kong, Lingping; Zhang, Chuanfang; Wang, Jitong; Qiao, Wenming; Ling, Licheng; Long, Donghui

    2015-11-24

    Free-standing electrodes with high gravimetric/volumetric capacitance will open up potential applications in miniaturized consumer electronics. Herein, we report a simple synthesis technology of free-standing orthorhombic Nb2O5 (T-Nb2O5)/graphene composite papers for Li-intercalating pseudocapacitive electrodes. Through a facile polyol-mediated solvothermal reaction, the Nb2O5 nanodots are homogeneously decorated onto the surface of reduced graphite oxide (rGO), which can form a homogeneous Nb2O5/rGO colloidal suspension that can be easily fabricated into flexible composite papers. The heat-treated T-Nb2O5/graphene composite papers exhibit a nanoporous layer-stacked structure with good ionic-electric conductive pathways, high T-Nb2O5 loading of 74.2%, and high bulk density of 1.55 g cm(-3). Such T-Nb2O5/graphene composite papers show a superior pseudocapacitor performance as free-standing electrodes, as evidenced by an ultrahigh gravimetric/volumetric capacitance (620.5 F g(-1) and 961.8 F cm(-3) at 1 mV s(-1)) and excellent rate capability. Furthermore, an organic electrolyte-based asymmetric supercapacitor is assembled based on T-Nb2O5/graphene composite papers, which can deliver a high energy density of 47 W h kg(-1) and power density of 18 kW kg(-1).

  8. Characterisation and Modelling of Meshed Electrodes on Free Standing Polyvilylidene Difluoride (PVDF) Films for Enhanced Pyroelectric Energy Harvesting.

    Science.gov (United States)

    Zabek, Daniel; Taylor, John; Bowen, Chris

    2016-09-05

    Flexible pyroelectric energy generators provide unique features for harvesting temperature fluctuations which can be effectively enhanced using meshed electrodes that improve thermal conduction, convection and radiation into the pyroelectric. In this paper, thermal radiation energy is continuously harvested with pyroelectric free standing Polyvilylidene Difluoride (PVDF) films over a large number of heat heat cycles using a novel micro-sized symmetrical patterned meshed electrode. It is shown that, for the meshed electrode geometries considered in this work, the polarisation-field (P-E), current-field (I-E) characteristics and device capacitance are unaffected since the fringing fields were generally small; this is verified using numerical simulations and comparison with experimental measurements. The use of meshed electrodes has been shown to significantly improve both the open circuit voltage (16 V to 59 V) and closed-circuit current (9 nA to 32 nA). The pyroelectric alternating current (AC) is rectified for direct current (DC) storage and 30% reduction in capacitor charging time is achieved by using the optimum meshed electrodes. The use of meshed electrodes on ferroelectric materials provides an innovative route to improve their performance in applications such as wearable devices, novel flexible sensors and large scale pyroelectric energy harvesters.hese instructions give you guidelines for preparing papers for IEEE Transactions and Journals. Use this document as a template if you are using Microsoft Word 6.0 or later. Otherwise, use this document as an instruction set. The electronic file of your paper will be formatted further at IEEE. Paper titles should be written in uppercase and lowercase letters, not all uppercase. Avoid writing long formulas with subscripts in the title; short formulas that identify the elements are fine (e.g., "Nd-Fe-B"). Do not write "(Invited)" in the title. Full names of authors are preferred in the author field, but are not

  9. Analysis of urban land use in the megacity of Dhaka, Bangladesh: Roof-top detection in the context of assessing solar photovoltaic potential

    Science.gov (United States)

    Jaegermeyr, J.; Kabir, H.; Endlicher, W.

    2009-12-01

    The megacity of Dhaka, Bangladesh is considered to be one of the world’s fastest growing urban centers. With nearly 14 million people Dhaka currently faces tremendous power crisis. The available power supply of Dhaka Megacity is currently 1000-1200 MW against the maximum demand of nearly 2000 MW. The objective of this study is to classify land cover of Dhaka to locate roof-top areas which are adequate for solar photovoltaic applications. Usually this task is performed with additional building-heights data. With lack of that, we present an object-based classification approach which is based on high resolution Quickbird data only. Extensive formal buildings in Dhaka mostly have flat roof-tops made from concrete which are well suited for PV applications. The classification is focused to detect these ‘Bright Roof-Tops’ to assess a lower limit for potential PV areas. With that conservative approach bright roof-top areas of 10.554 km2 out of the city’s 134.282 km2 could be found. The overall classification accuracy is 0.918, the producer’s accuracy of ‘Bright Roof-Tops’ is 0.833. Preliminary result of the PhD work of Humayun Kabir indicates that the application of only 75 Wp stand-alone solar modules on these available bright roof-tops can generate nearly 1,000 MW of electricity. The application of solar modules with high capacity (i.e., >200 Wp) preferably through grid-connected PV systems can substantially meet-up the city’s power demand, although several techno-economic and socio-political factors are certainly involved.

  10. A novel route to large-scale and robust free-standing TiO{sub 2} nanotube membranes based on N{sub 2} gas blowing combined with methanol wetting

    Energy Technology Data Exchange (ETDEWEB)

    Ali, Ghafar; Yoo, Seung Hwa; Kum, Jong Min; Kim, Yong Nam; Cho, Sung Oh [Department of Nuclear and Quantum Engineering, Korea Advanced Institute of Science and Technology (KAIST), 373-1 Guseong, Yuseong, Daejeon 305-701 (Korea, Republic of)

    2011-06-17

    We present a novel and straightforward approach to fabricate large-scale and robust free-standing TiO{sub 2} nanotube (TNT) membranes. Simply by blowing N{sub 2} gas onto as-anodized TNTs that are wetted with methanol, free-standing TNT membranes are produced. The approach also provides homogeneous and honeycomb-like Ti substrates after the detachment of TNT membranes. Through the second anodization of the honeycomb-like Ti substrates following the N{sub 2} blowing, TNT membranes comprising hexagonally close-packed and regularly ordered TNTs with clear open ends can be achieved. Characterization of the free-standing TNT membranes using Raman spectroscopy and a high-resolution transmission electron microscope reveals that anatase TiO{sub 2} and crystalline graphitic carbon are embedded in the bottom surface of the free-standing TNT membranes.

  11. Molecular beam epitaxy of free-standing bulk wurtzite AlxGa1-xN layers using a highly efficient RF plasma source

    OpenAIRE

    2016-01-01

    Recent developments with group III nitrides suggest AlxGa1-xN based LEDs can be new alternative commer-cially viable deep ultra-violet light sources. Due to a sig-nificant difference in the lattice parameters of GaN and AlN, AlxGa1-xN substrates would be preferable to either GaN or AlN for ultraviolet device applications. We have studied the growth of free-standing wurtzite AlxGa1-xN bulk crystals by plasma-assisted molecular beam epitaxy (PA-MBE) using a novel RF plasma source. Thick wurtz-i...

  12. The effect of free-standing GaN substrate on carrier localization in ultraviolet InGaN light-emitting diodes

    OpenAIRE

    Tsai, Ming-Ta; Chu, Chung-Ming; Huang, Che-Hsuan; Wu, Yin-Hao; Chiu, Ching-Hsueh; Li, Zhen-Yu; Tu, Po-Min; Lee, Wei-I; Kuo, Hao-Chung

    2014-01-01

    In this study, we have grown 380-nm ultraviolet light-emitting diodes (UV-LEDs) based on InGaN/AlInGaN multiple quantum well (MQW) structures on free-standing GaN (FS-GaN) substrate by atmospheric pressure metal-organic chemical vapor deposition (AP-MOCVD), and investigated the relationship between carrier localization degree and FS-GaN. The micro-Raman shift peak mapping image shows low standard deviation (STD), indicating that the UV-LED epi-wafer of low curvature and MQWs of weak quantum-c...

  13. Subharmonic resonant optical excitation of confined acoustic modes in a free-standing semiconductor membrane at GHz frequencies with a high-repetition-rate femtosecond laser.

    Science.gov (United States)

    Bruchhausen, A; Gebs, R; Hudert, F; Issenmann, D; Klatt, G; Bartels, A; Schecker, O; Waitz, R; Erbe, A; Scheer, E; Huntzinger, J-R; Mlayah, A; Dekorsy, T

    2011-02-18

    We propose subharmonic resonant optical excitation with femtosecond lasers as a new method for the characterization of phononic and nanomechanical systems in the gigahertz to terahertz frequency range. This method is applied for the investigation of confined acoustic modes in a free-standing semiconductor membrane. By tuning the repetition rate of a femtosecond laser through a subharmonic of a mechanical resonance we amplify the mechanical amplitude, directly measure the linewidth with megahertz resolution, infer the lifetime of the coherently excited vibrational states, accurately determine the system's quality factor, and determine the amplitude of the mechanical motion with femtometer resolution.

  14. Tailoring morphology in free-standing anodic aluminium oxide: control of barrier layer opening down to the sub-10 nm diameter.

    Science.gov (United States)

    Gong, Jie; Butler, William H; Zangari, Giovanni

    2010-05-01

    Free-standing, highly ordered porous aluminium oxide templates were fabricated by three-step anodization in oxalic, sulfuric or phosphoric acid solutions, followed by dissolution of the aluminium substrate in HgCl(2). Opening of the pore bottoms on the barrier layer side of these templates was carried out by using chemical or ion beam etching. Chemical etching is capable of achieving full pore opening, but partial pore opening occurs inhomogeneously. On the contrary, ion beam etching enables homogeneous and reproducible partial pore opening, with the pore size controlled through the etching time. By this method, pore openings as small as 5 nm can reliably be obtained.

  15. Plasmonic Light Trapping in Ultrathin Single Crystal Silicon Membrane for Solar Cells Application

    Science.gov (United States)

    2015-06-14

    for solar cell applications. Sub-ten micrometer free standing silicon membranes were produced by the chemical etching of silicon wafers. The produced...membranes were observed to be mechanically flexible, yet sufficiently sturdy to tolerate the different processing steps during solar cell fabrication...Approved for public release; distribution is unlimited. Plasmonic Light Trapping in Ultrathin Single Crystal Silicon Membrane for Solar Cells

  16. Free-standing electrodes composed of carbon-coated Li4Ti5O12 nanosheets and reduced graphene oxide for advanced sodium ion batteries

    Science.gov (United States)

    Xu, Guobao; Tian, Ye; Wei, Xiaolin; Yang, Liwen; Chu, Paul K.

    2017-01-01

    A free-standing electrode composed of carbon-coated Li4Ti5O12 nanosheets and reduced graphene oxide (designated as LTO-C/RGO) is fabricated for Na storage by modified vacuum filtration and subsequent annealing. In this process, graphene oxide with negative charges and LTO-C nanosheets with abundant charged ions are self-assembled into the nanocomposite based on the screening effect of electrostatic repulsion. The unique structure of the confined LTO-C nanosheets in a highly conductive interconnected RGO network not only promotes the reaction kinetics and structural stability of the electrodes during Na+ insertion/extraction, but also provides plenty of interfacial sites for Na+ adsorption giving rise to additional interfacial Na storage. The free-standing LTO-C/RGO anode for sodium ion battery exhibits a high capacity of 166 mAhg-1 at 1 C, good rate capability of 98.7 mAhg-1 at 5 C, and superior cyclic performance of 114 mAhg-1 at 2 C after 600 cycles. The materials boasting superior Na storage have large potential in high-performance sodium ion batteries in portable, flexible and wearable electronics.

  17. AlGaN/GaN high electron mobility transistors with a low sub-threshold swing on free-standing GaN wafer

    Directory of Open Access Journals (Sweden)

    Xinke Liu

    2017-09-01

    Full Text Available This paper reported AlGaN/GaN high electron mobility transistors (HEMTs with low sub-threshold swing SS on free-standing GaN wafer. High quality AlGaN/GaN epi-layer has been grown by metal-organic chemical vapor deposition (MOCVD on free-standing GaN, small full-width hall maximum (FWHM of 42.9 arcsec for (0002 GaN XRD peaks and ultralow dislocation density (∼104-105 cm-2 were obtained. Due to these extremely high quality material properties, the fabricated AlGaN/GaN HEMTs achieve a low SS (∼60 mV/decade, low hysteresis of 54 mV, and high peak electron mobility μeff of ∼1456 cm2V-1s-1. Systematic study of materials properties and device characteristics exhibits that GaN-on-GaN AlGaN/GaN HEMTs are promising candidate for next generation high power device applications.

  18. AlGaN/GaN high electron mobility transistors with a low sub-threshold swing on free-standing GaN wafer

    Science.gov (United States)

    Liu, Xinke; Gu, Hong; Li, Kuilong; Guo, Lunchun; Zhu, Deliang; Lu, Youming; Wang, Jianfeng; Kuo, Hao-Chung; Liu, Zhihong; Liu, Wenjun; Chen, Lin; Fang, Jianping; Ang, Kah-Wee; Xu, Ke; Ao, Jin-Ping

    2017-09-01

    This paper reported AlGaN/GaN high electron mobility transistors (HEMTs) with low sub-threshold swing SS on free-standing GaN wafer. High quality AlGaN/GaN epi-layer has been grown by metal-organic chemical vapor deposition (MOCVD) on free-standing GaN, small full-width hall maximum (FWHM) of 42.9 arcsec for (0002) GaN XRD peaks and ultralow dislocation density (˜104-105 cm-2) were obtained. Due to these extremely high quality material properties, the fabricated AlGaN/GaN HEMTs achieve a low SS (˜60 mV/decade), low hysteresis of 54 mV, and high peak electron mobility μeff of ˜1456 cm2V-1s-1. Systematic study of materials properties and device characteristics exhibits that GaN-on-GaN AlGaN/GaN HEMTs are promising candidate for next generation high power device applications.

  19. Fibre-rich additives--the effect on staling and their function in free-standing and pan-baked bread.

    Science.gov (United States)

    Purhagen, Jeanette K; Sjöö, Malin E; Eliasson, Ann-Charlotte

    2012-04-01

    The use of dietary fibre in bread products is increasing because of consumer demand for healthier products. However, an increase in dietary fibre level changes the rheological properties of the dough and also the quality properties of the final bread product. In this study, effects on dough and bread staling were followed after replacing 3% of wheat flour by fibre-rich additives (fine durum, oat bran, rye bran and wheat bran). Free-standing and pan-baked loaves were baked to compare the influence of baking method and loaf shape. All additives increased dough stability, with oat bran giving the greatest stability and longest development time. Parameters measured during storage were distribution, migration and loss of water, cutability, crumbliness, firmness and springiness. Furthermore, amylopectin retrogradation and amylase-lipid complex formation were assessed. Oat bran provided similar or better results than the control for all staling parameters, while other additives gave no general improvements. Cutability reached a plateau when crumb firmness was ≥ 4 N. Small amounts of fibre-rich additives had a significant influence on staling. However, the baking method (free-standing or pan-baked bread) had a greater impact on staling than the additives, thus displaying the importance of the baking method. Cutability was found to be related to firmness. Copyright © 2011 Society of Chemical Industry.

  20. Toward DNA electrochemical sensing by free-standing ZnO nanosheets grown on 2D thin-layered MoS2.

    Science.gov (United States)

    Yang, Tao; Chen, Meijing; Kong, Qianqian; Luo, Xiliang; Jiao, Kui

    2017-03-15

    Very recently, the 2-dimensional MoS2 layer as base substrate integrated with other materials has caused people's emerging attention. In this paper, a thin-layered MoS2 was prepared through an ultrasonic exfoliation method from bulk MoS2 and then the free-standing ZnO nanosheet was electrodeposited on the MoS2 scaffold for DNA sensing. The ZnO/MoS2 nanocomposite revealed smooth and vertical nanosheets morphology by scanning electron microscopy, compared with the sole MoS2 and sole ZnO. Importantly, the partially negative charged MoS2 layer is beneficial to the nucleation and growth of ZnO nanosheets under the effect of electrostatic interactions. Classic methylene blue, which possesses different affinities to dsDNA and ssDNA, was adopted as the measure signal to confirm the immobilization and hybridization of DNA on ZnO nanosheets and pursue the optimal synthetic conditions. And the results demonstrated that the free-standing ZnO/MoS2 nanosheets had low detection limit (6.6×10(-16)M) and has a positive influence on DNA immobilization and hybridization.

  1. Wave-like free-standing NiCo2O4 cathode for lithium-oxygen battery with high discharge capacity

    Science.gov (United States)

    Shen, Chen; Wen, Zhaoyin; Wang, Fan; Rui, Kun; Lu, Yan; Wu, Xiangwei

    2015-10-01

    A novel free-standing air electrode for Li-O2 battery with a wave-like microstructure is designed and synthesized through a facile electrochemical deposition process. Interconnected NiCo2O4 nanosheets with planes grown almost parallel to the surface of Ni foam build up continues porous catalytic surface with open space for the growth of Li2O2 discharge product. Li-O2 battery with the synthesized cathode delivers a high discharge capacity of 7004 mAh g-1 at 40 mA g-1 with a charge potential lower than 3.6 V (vs. Li/Li+), and significantly lower impedance compared to conventional electrode. Flower-like Li2O2 particles with a large size are observed as discharge products, consisting with the high discharge capacity. The unique wave-like microstructure and DMSO-based electrolyte with a high-doner-number are proposed to be responsible for the high discharge capacity, and the formation of large size Li2O2 discharge products. In addition, the electrode also exhibits stable cycle performance up to 100 cycles at the current density of 100 mA g-1 due to the robust composition and microstructure of the free-standing design.

  2. Vertical α-FeOOH nanowires grown on the carbon fiber paper as a free-standing electrode for sensitive H2O2 detection

    Institute of Scientific and Technical Information of China (English)

    Shichao Du; Zhiyu Ren; Jun WU; Wang Xi; Honggang Fu

    2016-01-01

    Highly sensitive,selective,and stable hydrogen peroxide (H2O2) detection using nanozyme-based catalysts are desirable for practical applications.Herein,vertical α-FeOOH nanowires were successfully grown on the surface of carbon fiber paper (CFP) via a low-temperature hydrothermal procedure.The formation of vertical α-FeOOH nanowires is ascribed to the structure-directing role of sodium dodecyl sulfate.The resulting free-standing electrode with one-dimensional (1D)nanowires offers oriented channels for fast charge transfer,excellent electrical contact between the electrocatalyst and the current collector,and good mechanical stability and reproducibility.Thus,it can serve as an efficient electrocatalyst for the reduction and sensitive detection of H2O2.The relation of the oxidation current of H2O2 with the concentration is linear from 0.05 to 0.5 mM with a sensitivity of-0.194 mA/(mM.cm2) and a low detection limit of 18 μM.Furthermore,the portability in the geometric tailor and easy device fabrication allow extending the general applicability of this free-standing electrode to chemical and biological sensors.

  3. Successful entrapment of carbon dots within flexible free-standing transparent mesoporous organic-inorganic silica hybrid films for photonic applications

    Science.gov (United States)

    Vassilakopoulou, Anastasia; Georgakilas, Vasilios; Vainos, Nikolaos; Koutselas, Ioannis

    2017-04-01

    The effective entrapment of Carbon dots (CDs) into a polymer-silica hybrid matrix, formed as free standing transparent flexible films, is presented. The composite's synthesis, characterization, device application and properties -mechanical, thermal and optical- are being provided and discussed. CDs of 3 nm mean size with strong photoluminescence are embedded into a silica matrix during the sol-gel procedure, using tetraethyl orthosilicate as the precursor and F127 triblock copolymer as the structure directing agent under acidic conditions. The final hybrid nanostructure forms free standing transparent films that show high flexibility and long term stable CDs luminescence indicating the protective character of the hybrid matrix. It is crucial that the photoluminescence of the hybrid's CDs is not seriously affected after thermal treatment at 550 °C for 30 min. Moreover, the herein reported hybrid is demonstrated to be suitable for the fabrication of advanced photonic structures using soft lithography processes due to its low shrinkage and distortion upon drying, both attributable to its porosity. Finally, it is reported that addition of F127 ethanolic solution in aqueous solution of CDs induces a blue-shift of their photoluminescence.

  4. Large-scale synthesis of flexible free-standing SERS substrates with high sensitivity: electrospun PVA nanofibers embedded with controlled alignment of silver nanoparticles.

    Science.gov (United States)

    He, Dian; Hu, Bo; Yao, Qiao-Feng; Wang, Kan; Yu, Shu-Hong

    2009-12-22

    A new and facile way to synthesize a free-standing and flexible surface-enhanced Raman scattering (SERS) substrate has been successfully developed, where high SERS-active Ag dimers or aligned aggregates are assembled within poly(vinyl alcohol) (PVA) nanofibers with chain-like arrays via electrospinning technique. The aggregation state of the obtained Ag nanoparticle dimers or larger, which are formed in a concentrated PVA solution, makes a significant contribution to the high sensitivity of SERS to 4-mercaptobenzoic acid (4-MBA) molecules with an enhancement factor (EF) of 10(9). The superiority of enhancement ability of this Ag/PVA nanofiber mat is also shown in the comparison to other substrates. Furthermore, the Ag/PVA nanofiber mat would keep a good reproducibility under a low concentration of 4-MBA molecule (10(-6) M) detection with the average RSD values of the major Raman peak less than 0.07. The temporal stability of the substrate has also been demonstrated. This disposable, easy handled, flexible free-standing substrate integrated the advantages including the superiority of high sensitivity, reproducibility, stability, large-scale, and low-cost production compared with other conventional SERS substrates, implying that it is a perfect choice for practical SERS detection application.

  5. High Energy Density All Solid State Asymmetric Pseudocapacitors Based on Free Standing Reduced Graphene Oxide-Co3O4 Composite Aerogel Electrodes.

    Science.gov (United States)

    Ghosh, Debasis; Lim, Joonwon; Narayan, Rekha; Kim, Sang Ouk

    2016-08-31

    Modern flexible consumer electronics require efficient energy storage devices with flexible free-standing electrodes. We report a simple and cost-effective route to a graphene-based composite aerogel encapsulating metal oxide nanoparticles for high energy density, free-standing, binder-free flexible pseudocapacitive electrodes. Hydrothermally synthesized Co3O4 nanoparticles are successfully housed inside the microporous graphene aerogel network during the room temperature interfacial gelation at the Zn surface. The resultant three-dimensional (3D) rGO-Co3O4 composite aerogel shows mesoporous quasiparallel layer stack morphology with a high loading of Co3O4, which offers numerous channels for ion transport and a 3D interconnected network for high electrical conductivity. All solid state asymmetric pseudocapacitors employing the composite aerogel electrodes have demonstrated high areal energy density of 35.92 μWh/cm(2) and power density of 17.79 mW/cm(2) accompanied by excellent cycle life.

  6. Comparison between experiment and theory in the temperature variation of film tension above the bulk isotropic transition in free-standing liquid-crystal films.

    Science.gov (United States)

    Veum, M; Duelge, L; Droske, J; Nguyen, H T; Huang, C C; Mirantsev, L V

    2009-09-01

    Using differential scanning calorimetry, the transition enthalpies and temperatures for the bulk smectic-isotropic phase transition have been measured for a series of liquid-crystal compounds. For five compounds, those values were used as parameters in a microscopic mean-field model to predict the temperature dependence of the difference in free-energy density between a sample of material in a free-standing smectic film and that in the bulk. The model predicts a weak temperature dependence below the bulk clearing point and a pronounced monotonic increase with temperature above the transition temperature. The compounds used in this study were chosen specifically because they were also the subject of a previous independent experimental study [M. Veum, Phys. Rev. E 74, 011703 (2006)] that demonstrated a sudden monotonic increase in the free-standing film tension with temperature, which is qualitatively consistent with the predictions of the above-mentioned mean-field model. This study presents a direct and quantitative comparison between the predictions of the mean-field model and the results from previous tension experiments.

  7. Relationship between oxygen impurity distribution in multicrystalline solar cell silicon and the use of top and side heaters during manufacture

    Science.gov (United States)

    Nakano, S.; Gao, B.; Kakimoto, K.

    2013-07-01

    The relationship between the oxygen impurity distribution in multicrystalline silicon and the use of top and/or side heaters in an unidirectional solidification process was investigated by numerical analysis. It was found that the oxygen concentration in the melt for the side heating system is lower than that for only the top heating system. This occurs because of the difference in flow direction of the melt near the crucible wall. The melt flows upward near the crucible wall when the side heating system is used. Oxygen is therefore dissolved from the silica crucible wall and is transported easily to the melt surface, where it evaporates.

  8. Enhancing the Photocurrent of Top-Cell by Ellipsoidal Silver Nanoparticles: Towards Current-Matched GaInP/GaInAs/Ge Triple-Junction Solar Cells

    Directory of Open Access Journals (Sweden)

    Yiming Bai

    2016-05-01

    Full Text Available A way to increase the photocurrent of top-cell is crucial for current-matched and highly-efficient GaInP/GaInAs/Ge triple-junction solar cells. Herein, we demonstrate that ellipsoidal silver nanoparticles (Ag NPs with better extinction performance and lower fabrication temperature can enhance the light harvest of GaInP/GaInAs/Ge solar cells compared with that of spherical Ag NPs. In this method, appropriate thermal treatment parameters for Ag NPs without inducing the dopant diffusion of the tunnel-junction plays a decisive role. Our experimental and theoretical results confirm the ellipsoidal Ag NPs annealed at 350 °C show a better extinction performance than the spherical Ag NPs annealed at 400 °C. The photovoltaic conversion efficiency of the device with ellipsoidal Ag NPs reaches 31.02%, with a nearly 5% relative improvement in comparison with the device without Ag NPs (29.54%. This function of plasmonic NPs has the potential to solve the conflict of sufficient light absorption and efficient carrier collection in GaInP top-cell devices.

  9. CAB-DWTM for 5 μm trace-width deposition of solar cell metallization top-contacts

    Energy Technology Data Exchange (ETDEWEB)

    Justin Hoey; Drew Thompson; Matt Robinson; Zakaria Mahmud; Orven F. Swenson; Iskander S. Akhatov; Douglas L. Schulz

    2009-06-08

    This paper reviews methods for creating solar cell grid contacts and explores how cell efficiency can be increased using CAB-DW{trademark}. Specifically, the efficiency of p-i-n structure solar cells built in-house with 90 {micro}m sputtered lines and 5 {micro}m CAB-DW lines were compared. Preliminary results of the comparison show a marked improvement in solar cell efficiency using CAB-DW. In addition to this, a theoretical and experimental analysis of the dynamics of particle impaction on a substrate (i.e. whether particle stick or bounce) will be discussed including how this analysis may lead to further improvement of CAB-DW.

  10. Ekspedeerimisfirmade TOP

    Index Scriptorium Estoniae

    2008-01-01

    Ekspedeerimisfirmade TOP 57. Vt. samas: Tanel Raig. Majandus kukutab ekspedeerimisturgu. Diagramm: Väliskaubanduse statistika; Katrin Raie. Ekspedeerijad hakkavad rohkem koostööle rõhuma. Kommenteerib Jaan Lepp; Müügitulu TOP 10; Müügitulu kasvu TOP 10; Kasumi TOP 10; Kasumi kasvu TOP 10; Rentaabluse TOP 10; Omakapitali tootlikkuse TOP 10; Eestis registreeritud Vene hiiglane; Ekspedeerimisturu kasumiliider kaotas 20 miljonit; Küsimustele vastab OÜ Contimer juht Dmitri Redkin

  11. Ekspedeerimisfirmade TOP

    Index Scriptorium Estoniae

    2008-01-01

    Ekspedeerimisfirmade TOP 57. Vt. samas: Tanel Raig. Majandus kukutab ekspedeerimisturgu. Diagramm: Väliskaubanduse statistika; Katrin Raie. Ekspedeerijad hakkavad rohkem koostööle rõhuma. Kommenteerib Jaan Lepp; Müügitulu TOP 10; Müügitulu kasvu TOP 10; Kasumi TOP 10; Kasumi kasvu TOP 10; Rentaabluse TOP 10; Omakapitali tootlikkuse TOP 10; Eestis registreeritud Vene hiiglane; Ekspedeerimisturu kasumiliider kaotas 20 miljonit; Küsimustele vastab OÜ Contimer juht Dmitri Redkin

  12. A supercell, Bloch wave method for calculating low-energy electron reflectivity with applications to free-standing graphene and molybdenum disulfide

    Science.gov (United States)

    McClain, John

    This dissertation reports on a novel theoretical and computational framework for calculating low-energy electron reflectivities from crystalline surfaces and its application to two layered systems of two-dimensional materials, graphene and molybdenum disulfide. The framework provides a simple and efficient approach through the matching of a small set of Fourier components of Bloch wave solutions to the Schrodinger Equation in a slab-in-supercell geometry to incoming and outgoing plane waves on both sides of the supercell. The implementation of this method is described in detail for the calculation of reflectivities in the lowest energy range, for which only specular reflection is allowed. This implementation includes the calculation of reflectivities from beams with normal or off-normal incidence. Two different algorithms are described in the case of off-normal incidence which differ in their dependence on the existence of a symmetry with a mirror plane parallel to the crystal surface. Applications to model potentials in one, two, and three dimensions display consistent results when using different supercell sizes and convergent results with the density of Fourier grids. The design of the Bloch wave matching also allows for the accurate modeling of crystalline slabs through the use of realistic potentials determined via density functional theory. The application of the method to low-energy electron scattering from free-standing systems of a few layers of graphene, including the use of these realistic potentials, demonstrates this ability of the method to accurately model real systems. It reproduces the layer-dependent oscillations found in experimental, normal incidence reflectivity curves for a few layers of graphene grown on silicon carbide. The normal incidence reflectivity curves calculated for slabs consisting of few-layer graphene on 10 layers of nickel show some qualitative agreement with experiment. General incidence reflectivity spectra for free-standing

  13. Free-standing hybrid film of less defective graphene coated with mesoporous TiO2 for flexible lithium ion batteries with fast charging/discharging capabilities

    Science.gov (United States)

    Feng, Bingmei; Wang, Huixin; Zhang, Yingqi; Shan, Xuyi; Liu, Min; Li, Feng; Guo, Jinghua; Feng, Jun; Fang, Hai-Tao

    2017-03-01

    Benefiting from extremely high conductivity, graphene sheets (GS) with very low defect density are preferable to reduced graphene oxide sheets for constructing the free-standing hybrid electrodes of flexible electrochemical energy storage devices. However, due to the hydrophobic nature and deficiency of nucleation sites, how to uniformly and intimately anchor electrochemically active materials onto less defective GS is a challenge. Herein, a free-standing and mechanically flexible hybrid film with two-layer structure, mesoporous TiO2 anchored less defective GS hybrid (mTiO2-GS) upper-layer and graphene under-layer, denoted as mTiO2-GS/G, is fabricated. The hydrolysis of a Ti glycolate aqueous sol solution were applied to form mTiO2. The decoration of less defective GS with sodium lignosulfonate (SLS) surfactant is crucial for anchoring TiO2 nanoparticles (NPs). The aromatic rings of SLS favor a non-destructive functionalization of GS through the π-π stacking interaction. The sulfonic acid groups and hydroxyl groups of SLS, respectively, greatly improve the dispersity of GS in water and trigger the nucleation of TiO2 through the oxolation in the hydrolysis of Ti glycolate sol solution. The following characteristics of free-standing mTiO2-GS/G electrode benefit the fast charging/discharging capabilities: highly conductive graphene framework, ultra-small NPs (˜5.0 nm) in mTiO2 anchored, high specific surface area (202.5 m2 g-1), abundant mesopores (0.32 cm3 g-1), intimate interfacial interaction between mTiO2 and GS, robust contact between the mTiO2-GS upper-layer and an under-layer of bare graphene as the current collector. In coin half-cells, the mTiO2-GS/G electrode delivers a capacity of 130 mA h g-1 at 50 C, and 71 mA h g-1 at 100 C, and it also exhibits excellent cycle stability up to 10 000 cycles under 10 C, with a degradation rate of 0.0033% per cycle. When packed in flexible cells, the mTiO2-GS/G electrode maintains fast charging/discharging capabilities

  14. Mussel-inspired adhesive and transferable free-standing films by self-assembling dexamethasone encapsulated BSA nanoparticles and vancomycin immobilized oxidized alginate.

    Science.gov (United States)

    Han, Lu; Wang, Zhen-ming; Lu, Xiong; Dong, Li; Xie, Chao-ming; Wang, Ke-feng; Chen, Xiao-lang; Ding, Yong-hui; Weng, Lu-tao

    2015-02-01

    This study developed an adhesive and transferable free-standing (FS) film with dual function of osteoinductivity and antibacterial activity, which was obtained by sequentially assembling vancomycin immobilized oxidized sodium alginate and dexamethasone encapsulated chitosan coated BSA nanoparticles on a poly-dopamine layer. The FS films enabled the dual release of vancomycin and dexamethasone. The FS films had excellent osteoinductivity and antibacterial activity by cell culture and antibacterial assay. The FS film was detached from substrates and transferred to non-fouling surfaces by a wet transfer method, which demonstrated that the adhesive FS film is potential to modify biopolymers with non-fouling surfaces in mild and biocompatible conditions for biomedical applications.

  15. Impact of barrier thickness on transistor performance in AlN/GaN high electron mobility transistors grown on free-standing GaN substrates

    Energy Technology Data Exchange (ETDEWEB)

    Deen, David A., E-mail: david.deen@alumni.nd.edu; Storm, David F.; Meyer, David J.; Bass, Robert; Binari, Steven C. [Electronics Science and Technology Division, Naval Research Laboratory, Washington, DC 20375-5347 (United States); Gougousi, Theodosia [Physics Department, University of Maryland Baltimore County, Baltimore, Maryland 21250 (United States); Evans, Keith R. [Kyma Technologies, Raleigh, North Carolina 27617 (United States)

    2014-09-01

    A series of six ultrathin AlN/GaN heterostructures with varied AlN thicknesses from 1.5–6 nm have been grown by molecular beam epitaxy on free-standing hydride vapor phase epitaxy GaN substrates. High electron mobility transistors (HEMTs) were fabricated from the set in order to assess the impact of barrier thickness and homo-epitaxial growth on transistor performance. Room temperature Hall characteristics revealed mobility of 1700 cm{sup 2}/V s and sheet resistance of 130 Ω/□ for a 3 nm thick barrier, ranking amongst the lowest room-temperature sheet resistance values reported for a polarization-doped single heterostructure in the III-Nitride family. DC and small signal HEMT electrical characteristics from submicron gate length HEMTs further elucidated the effect of the AlN barrier thickness on device performance.

  16. Bendable and thin sulfide solid electrolyte film: a new electrolyte opportunity for free-standing and stackable high-energy all-solid-state lithium-ion batteries.

    Science.gov (United States)

    Nam, Young Jin; Cho, Sung-Ju; Oh, Dae Yang; Lim, Jun-Muk; Kim, Sung Youb; Song, Jun Ho; Lee, Young-Gi; Lee, Sang-Young; Jung, Yoon Seok

    2015-05-13

    Bulk-type all-solid-state lithium batteries (ASLBs) are considered a promising candidate to outperform the conventional lithium-ion batteries. Unfortunately, the current technology level of ASLBs is in a stage of infancy in terms of cell-based (not electrode-material-based) energy densities and scalable fabrication. Here, we report on the first ever bendable and thin sulfide solid electrolyte films reinforced with a mechanically compliant poly(paraphenylene terephthalamide) nonwoven (NW) scaffold, which enables the fabrication of free-standing and stackable ASLBs with high energy density and high rate capabilities. The ASLB, using a thin (∼70 μm) NW-reinforced SE film, exhibits a 3-fold increase of the cell-energy-density compared to that of a conventional cell without the NW scaffold.

  17. ELECTROSYNTHESES OF FREE-STANDING POLY(THIOPHENE-3-ACETIC ACID) FILM IN MIXED ELECTROLYTES OF BORON TRIFLUORIDE DIETHYL ETHERATE AND TRIFLUOROACETIC ACID

    Institute of Scientific and Technical Information of China (English)

    Yu He; Wen-juan Guo; Mei-shan Pei; Guang-you Zhang

    2012-01-01

    High quality free-standing poly(thiophene-3-acetic acid) (PTAA),a water-soluble polythiophene derivative,was successfully electrosynthesized in boron trifluoride diethyl etherate (BFEE) + 25% (by volume) trifluoroacetic acid (TFA) at lower potential (0.38 V versus Pt).The carboxyl group makes PTAA highly soluble in water,facilitating its potential application as a blue-light-emitting material.PTAA films with conductivity of 7 S cm-1 obtained from this medium showed better redox activity and thermal stability.The structure and morphology of the polymer were studied by UV-Vis,FT-IR,1H-NMR spectra and scanning electron microscopy,respectively.

  18. Relativistic Electrons Produced by Reconnecting Electric Fields in a Laser-driven Bench-top Solar Flare

    Science.gov (United States)

    Zhong, J. Y.; Lin, J.; Li, Y. T.; Wang, X.; Li, Y.; Zhang, K.; Yuan, D. W.; Ping, Y. L.; Wei, H. G.; Wang, J. Q.; Su, L. N.; Li, F.; Han, B.; Liao, G. Q.; Yin, C. L.; Fang, Y.; Yuan, X.; Wang, C.; Sun, J. R.; Liang, G. Y.; Wang, F. L.; Ding, Y. K.; He, X. T.; Zhu, J. Q.; Sheng, Z. M.; Li, G.; Zhao, G.; Zhang, J.

    2016-08-01

    Laboratory experiments have been carried out to model the magnetic reconnection process in a solar flare with powerful lasers. Relativistic electrons with energy up to megaelectronvolts are detected along the magnetic separatrices bounding the reconnection outflow, which exhibit a kappa-like distribution with an effective temperature of ˜109 K. The acceleration of non-thermal electrons is found to be more efficient in the case with a guide magnetic field (a component of a magnetic field along the reconnection-induced electric field) than in the case without a guide field. Hardening of the spectrum at energies ≥500 keV is observed in both cases, which remarkably resembles the hardening of hard X-ray and γ-ray spectra observed in many solar flares. This supports a recent proposal that the hardening in the hard X-ray and γ-ray emissions of solar flares is due to a hardening of the source-electron spectrum. We also performed numerical simulations that help examine behaviors of electrons in the reconnection process with the electromagnetic field configurations occurring in the experiments. The trajectories of non-thermal electrons observed in the experiments were well duplicated in the simulations. Our numerical simulations generally reproduce the electron energy spectrum as well, except for the hardening of the electron spectrum. This suggests that other mechanisms such as shock or turbulence may play an important role in the production of the observed energetic electrons.

  19. Integrated fast assembly of free-standing lithium titanate/carbon nanotube/cellulose nanofiber hybrid network film as flexible paper-electrode for lithium-ion batteries.

    Science.gov (United States)

    Cao, Shaomei; Feng, Xin; Song, Yuanyuan; Xue, Xin; Liu, Hongjiang; Miao, Miao; Fang, Jianhui; Shi, Liyi

    2015-05-27

    A free-standing lithium titanate (Li4Ti5O12)/carbon nanotube/cellulose nanofiber hybrid network film is successfully assembled by using a pressure-controlled aqueous extrusion process, which is highly efficient and easily to scale up from the perspective of disposable and recyclable device production. This hybrid network film used as a lithium-ion battery (LIB) electrode has a dual-layer structure consisting of Li4Ti5O12/carbon nanotube/cellulose nanofiber composites (hereinafter referred to as LTO/CNT/CNF), and carbon nanotube/cellulose nanofiber composites (hereinafter referred to as CNT/CNF). In the heterogeneous fibrous network of the hybrid film, CNF serves simultaneously as building skeleton and a biosourced binder, which substitutes traditional toxic solvents and synthetic polymer binders. Of importance here is that the CNT/CNF layer is used as a lightweight current collector to replace traditional heavy metal foils, which therefore reduces the total mass of the electrode while keeping the same areal loading of active materials. The free-standing network film with high flexibility is easy to handle, and has extremely good conductivity, up to 15.0 S cm(-1). The flexible paper-electrode for LIBs shows very good high rate cycling performance, and the specific charge/discharge capacity values are up to 142 mAh g(-1) even at a current rate of 10 C. On the basis of the mild condition and fast assembly process, a CNF template fulfills multiple functions in the fabrication of paper-electrode for LIBs, which would offer an ever increasing potential for high energy density, low cost, and environmentally friendly flexible electronics.

  20. Reconciling Differences between Lipid Transfer in Free-Standing and Solid Supported Membranes: A Time-Resolved Small-Angle Neutron Scattering Study.

    Energy Technology Data Exchange (ETDEWEB)

    Wah, Benny; Breidigan, Jeffrey M.; Adams, Joseph; Horbal, Piotr; Garg, Sumit; Porcar, Lionel; Perez-Salas, Ursula

    2017-04-11

    Maintaining compositional lipid gradients across membranes in animal cells is essential to biological function, but what is the energetic cost to maintain these differences? It has long been recognized that studying the passive movement of lipids in membranes can provide insight into this toll. Confusingly the reported values of inter- and, particularly, intra-lipid transport rates of lipids in membranes show significant differences. To overcome this difficulty, biases introduced by experimental approaches have to be identified. The present study addresses the difference in the reported intramembrane transport rates of dimyristoylphosphatidylcholine (DMPC) on flat solid supports (fast flipping) and in curved free-standing membranes (slow flipping). Two possible scenarios are potentially at play: one is the difference in curvature of the membranes studied and the other the presence (or not) of the support. Using DMPC vesides and DMPC supported membranes on silica nanoparticles of different radii, we found that an increase in curvature (from a diameter of 30 nm to a diameter of 100 nm) does not change the rates significantly, differing only by factors of order I. Additionally, we found that the exchange rates of DMPC in supported membranes are similar to the ones in vesicles. And as previously reported, we found that the activation energies for exchange on free-standing and supported membranes are similar (84 and 78 kJ/mol, respectively). However, DMPC's flip-flop rates increase significantly when in a supported membrane, surpassing the exchange rates and no longer limiting the exchange process. Although the presence of holes or cracks in supported membranes explains the occurrence of fast lipid flip-flop in many studies, in defect-free supported membranes we find that fast flip-flop is driven by the surface's induced disorder of the bilayer's acyl chain packing as evidenced from their broad melting temperature behavior.

  1. Fermi acceleration at fast shock in a solar flare and impulsive loop-top hard X-ray source

    CERN Document Server

    Tsuneta, S; Tsuneta, Saku; Naito, Tsuguya

    1998-01-01

    We propose that non-thermal electrons are efficiently accelerated by first-order Fermi process at the fast shock, as a natural consequence of the new magnetohydrodynamic picture of the flaring region revealed with Yohkoh. An oblique fast shock is naturally formed below the reconnection site, and boosts the acceleration to significantly decrease the injection energy. The slow shocks attached to the reconnection X-point heat the plasma up to 10--20 MK, exceeding the injection energy. The combination of the oblique shock configuration and the pre-heating by the slow shock allows bulk electron acceleration from the thermal pool. The accelerated electrons are trapped between the two slow shocks due to the magnetic mirror downstream of the fast shock, thus explaining the impulsive loop-top hard X-ray source discovered with Yohkoh. Acceleration time scale is ~ 0.3--0.6 s, which is consistent with the time scale of impulsive bursts. When these electrons stream away from the region enclosed by the fast shock and the s...

  2. Micro pore arrays in free standing cyclic olefin copolymer membranes: fabrication and surface functionalization strategies for in-vitro barrier tissue models

    Science.gov (United States)

    Gel, M.; Kandasamy, S.; Cartledge, K.; Be, C. L.; Haylock, D.

    2013-12-01

    In recent years there has been growing interest in micro engineered in-vitro models of tissues and organs. These models are designed to mimic the in-vivo like physiological conditions with a goal to study human physiology in an organ-specific context or to develop in-vitro disease models. One of the challenges in the development of these models is the formation of barrier tissues in which the permeability is controlled locally by the tissues cultured at the interface. In-vitro models of barrier tissues are typically created by generating a monolayer of cells grown on thin porous membranes. This paper reports a robust preparation method for free standing porous cyclic olefin copolymer (COC) membranes. We also demonstrate that gelatin coated membranes facilitate formation of highly confluent monolayer of HUVECs. Membranes with thickness in the range of 2-3 um incorporating micro pores with diameter approximately 20 um were fabricated and integrated with microfluidic channels. The performance of the device was demonstrated with a model system mimicking the endothelial barrier in bone marrow sinusoids.

  3. Synthesis of free-standing carbon nanohybrid by directly growing carbon nanotubes on air-sprayed graphene oxide paper and its application in supercapacitor

    Science.gov (United States)

    Wei, Li; Jiang, Wenchao; Yuan, Yang; Goh, Kunli; Yu, Dingshan; Wang, Liang; Chen, Yuan

    2015-04-01

    We report the synthesis of a free-standing two dimensional carbon nanotube (CNT)-reduced graphene oxide (rGO) hybrid by directly growing CNTs on air-sprayed GO paper. As a result of the good integration between CNTs and thermally reduced GO film during chemical vapor deposition, excellent electrical conductivity (2.6×104 S/m), mechanical flexibility (electrical resistance only increases 1.1% after bent to 90° for 500 times) and a relatively large surface area (335.3 m2/g) are achieved. Two-electrode supercapacitor assembled using the CNT-rGO hybrids in ionic liquid electrolyte (1-ethyl-3-methylimidazolium tetrafluoroborate) shows excellent stability upon 500 bending cycles with the gravimetric energy density measuring 23.7 Wh/kg and a power density of 2.0 kW/kg. Furthermore, it shows an impedance phase angle of -64.4° at a frequency of 120 Hz, suggesting good potentials for 120 Hz alternating current line filtering applications.

  4. Transition Helmholtz free energy, entropy, and heat capacity of free-standing smectic films in water: A mean-field treatment

    Energy Technology Data Exchange (ETDEWEB)

    Śliwa, Izabela, E-mail: izasliwa@ifmpan.poznan.pl [Institute of Molecular Physics, Polish Academy of Sciences, Smoluchowskiego 17, 60-179 Poznaǹ (Poland); Zakharov, A. V., E-mail: alexandre.zakharov@yahoo.ca [Saint Petersburg Institute for Machine Sciences, The Russian Academy of Sciences, Saint Petersburg 199178 (Russian Federation)

    2014-11-21

    Using the extended McMillan's mean field approach with anisotropic forces a study of both the structural and thermodynamic properties of free-standing smectic film (FSSF) in water on heating to the isotropic temperature is carried out numerically. By solving the self-consistent nonlinear equations for the order parameters, we obtained that the smectic-A-isotropic (AI) transition occurs through the series of layer-thinning transitions causing the films to thin in the stepwise manner as the temperature is increased above the bulk smectic-A-isotropic temperature T{sub AI}(bulk). With enhanced pair interactions in the bounding layers, the smectic-isotropic transition corresponds to smectic melting of the central layers. The effects of surface “enhanced” pair interactions in the bounding layers and of film thickness on the orientational and translational order parameters, the Helmholtz free energy and entropy, as well as the temperature dependence of the heat capacity of FSSFs, have also been investigated. Reasonable agreement between the theoretically predicted and the experimentally obtained – by means of optical microscopy and ellipsometry techniques – data of the temperature when the thin decylcyanobiphenyl smectic film immersing in water ruptures has been obtained.

  5. Synthesis of free-standing carbon nanohybrid by directly growing carbon nanotubes on air-sprayed graphene oxide paper and its application in supercapacitor

    Energy Technology Data Exchange (ETDEWEB)

    Wei, Li; Jiang, Wenchao; Yuan, Yang; Goh, Kunli; Yu, Dingshan [School of Chemical and Biomedical Engineering, Nanyang Technological University, 62 Nanyang Drive, Singapore 637459 (Singapore); Wang, Liang [School of Chemistry and Chemical Engineering, Tianjin University of Technology, Tianjin 300384 (China); Chen, Yuan, E-mail: chenyuan@ntu.edu.sg [School of Chemical and Biomedical Engineering, Nanyang Technological University, 62 Nanyang Drive, Singapore 637459 (Singapore)

    2015-04-15

    We report the synthesis of a free-standing two dimensional carbon nanotube (CNT)-reduced graphene oxide (rGO) hybrid by directly growing CNTs on air-sprayed GO paper. As a result of the good integration between CNTs and thermally reduced GO film during chemical vapor deposition, excellent electrical conductivity (2.6×10{sup 4} S/m), mechanical flexibility (electrical resistance only increases 1.1% after bent to 90° for 500 times) and a relatively large surface area (335.3 m{sup 2}/g) are achieved. Two-electrode supercapacitor assembled using the CNT–rGO hybrids in ionic liquid electrolyte (1-ethyl-3-methylimidazolium tetrafluoroborate) shows excellent stability upon 500 bending cycles with the gravimetric energy density measuring 23.7 Wh/kg and a power density of 2.0 kW/kg. Furthermore, it shows an impedance phase angle of −64.4° at a frequency of 120 Hz, suggesting good potentials for 120 Hz alternating current line filtering applications. - Graphical abstract: Flexible and highly conductive carbon nanotube-reduced graphene oxide nanohybrid. - Highlights: • Direct growth of carbon nanotubes by chemical vapor deposition on air-sprayed graphene oxide paper. • Two-dimensional carbon nanohybrid with excellent conductivity and mechanical flexibility. • Supercapacitor with excellent performance stability upon mechanical deformation for flexible electronics applications. • Supercapacitor with high impedance phase angle for 120 Hz alternating current line filtering applications.

  6. Poly(3,4-ethylene-dioxythiophene)-poly(styrenesulfonate) glued and graphene encapsulated sulfur-carbon film for high-performance free-standing lithium-sulfur batteries

    Science.gov (United States)

    Wang, Zhiyu; Cheng, Jianli; Ni, Wei; Gao, Lizhen; Yang, Dan; Razal, Joselito M.; Wang, Bin

    2017-02-01

    A novel free-standing composite film electrode for Li-S battery is investigated. This novel electrode consists of polyvinylpyrrolidone-coated hollow sulfur microspheres (PVPS) that are homogeneously confined within the conductive composite matrix of graphene and poly(3,4-ethylene-dioxythiophene)-poly(styrenesulfonate) (PEDOT-PSS). The characteristic large surface area and wrinkled surface of graphene sheets allow the formation of a conductive layer on the surface of PVPS to suppress the polysulfide dissolution and accommodate the volumetric expansion of sulfur. The addition of PEDOT-PSS also enhances the adhesion between the PVPS and the graphene surface, the overall conductivity of the electrode, and the charge transportation during the charging and discharging processes. The best electrode performances are achieved for a composite film cathode with a sulfur content of about 63.9%, which delivers an initial specific capacity of around 1060 mAh g-1 at 0.1 C. This electrode also displays an excellent capacity retention of 75% after 500 cycles at 1C, corresponding to a capacity decay of only 0.05% per cycle.

  7. Aqueous chemical growth of free standing vertical ZnO nanoprisms, nanorods and nanodiskettes with improved texture co-efficient and tunable size uniformity

    Energy Technology Data Exchange (ETDEWEB)

    Ram, S.D.G. [Bharath Niketan Engineering College, Department of Physics, Aundipatti (India); Ravi, G.; Mahalingam, T. [Alagappa University, Department of Physics, Karaikudi (India); Athimoolam, A. [Fatima Michael College of Engineering and Technology, Department of Physics, Madurai (India); Kulandainathan, M.A. [Central Electro Chemical Research Institute, Karaikudi (India)

    2011-12-15

    Tuning the morphology, size and aspect ratio of free standing ZnO nanostructured arrays by a simple hydrothermal method is reported. Pre-coated ZnO seed layers of two different thicknesses ({approx}350 nm or 550 nm) were used as substrates to grow ZnO nanostructures for the study. Various parameters such as chemical ambience, pH of the solution, strength of the Zn{sup 2+} atoms and thickness of seed bed are varied to analyze their effects on the resultant ZnO nanostructures. Vertically oriented hexagonal nanorods, multi-angular nanorods, hexagonal diskette and popcorn-like nanostructures are obtained by altering the experimental parameters. All the produced nanostructures were analysed by X-ray powder diffraction analysis and found to be grown in the (002) orientation of wurtzite ZnO. The texture co-efficient of ZnO layer was improved by combining a thick seed layer with higher cationic strength. Surface morphological studies reveal various nanostructures such as nanorods, diskettes and popcorn-like structures based on various preparation conditions. The optical property of the closest packed nanorods array was recorded by UV-VIS spectrometry, and the band gap value simulated from the results reflect the near characteristic band gap of ZnO. The surface roughness profile taken from the Atomic Force Microscopy reveals a roughness of less than 320 nm. (orig.)

  8. Investigation of Free-Standing Plasmonic Mesoporous Ag/CMK-8-Nafion Composite Membrane for the Removal of Organic Pollutants with 254-nm UV Irradiation

    Science.gov (United States)

    Tseng, Chuan Ming; Chen, Hsin Liang; Lai, Sz Nian; Chen, Ming Shiung; Peng, Chien Jung; Li, Chia Jui; Hung, Wei Hsuan

    2017-05-01

    "Carbon-based material" has demonstrated a great potential on water purification due to its strong physical adsorption to organic pollutants in the water. Three-dimensional cubic ordered mesoporous carbon (CMK-8), one of the well-known ordered mesoporous carbons, was prepared by using nanocasting method with mesoporous silica (KIT-6) as the template. In this study, CMK-8 blended with Nafion polymer to form a free-standing mesoporous CMK-8-Nafion composite membrane. The synthesis of high crystallinity CMK-8 was characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). More than 80% methyl orange (MO) removal efficiency was observed under 254-nm UV irradiation after 120 min. Ninety-two percent recycling performance was remained after four recycling tests, which indicated a reliable servicing lifetime for the water purification. Furthermore, an additional layer of plasmonic silver nanoparticles (Ag NPs) was integrated into this CMK-8-Nafion membrane for higher pollutant removal efficiency, attributing from the generation of plasmon-resonance hot electrons from Ag NPs. A 4-in. CMK-8-Nafion composite membrane was also fabricated for the demonstration of potential large-scale utilization.

  9. Flexible and free-standing ternary Cd₂GeO₄ nanowire/graphene oxide/CNT nanocomposite film with improved lithium-ion battery performance.

    Science.gov (United States)

    Wang, Linlin; Zhang, Xiaozhu; Shen, Guozhen; Peng, Xia; Zhang, Min; Xu, Jingli

    2016-03-01

    To realize flexible lithium-ion batteries (LIBs), the design of flexible electrode/current collector materials with high mechanical flexibility, superior conductivity and excellent electrochemical performance and electrical stability are highly desirable. In this work, we developed a new ternary Cd2GeO4 nanowire/graphene oxide/carbon nanotube nanocomposite (Cd2GeO4 NW/GO/CNT) film electrode. Benefiting from the efficient combination of GO and Cd2GeO4 NWs, our Cd2GeO4 NW/GO/CNT composite film exhibits a capacity of 784 mA h g(-1) after 30 cycles at 200 mA g(-1), which is 2.7 times higher than that of Cd2GeO4 NW/CNT film (290 mA h g(-1)). At a higher rate of 400 mA g(-1) and 1 A g(-1), the Cd2GeO4 NW/GO/CNT film delivers a stable capacity of 617 and 397 mA h g(-1), respectively. Even at 2.5 A g(-1), it still exhibits a high rate capacity of 180 mA h g(-1). The flexible Cd2GeO4 NW/GO/CNT film clearly demonstrates good cycling stability and rate performance for anode materials in LIBs. This route may be extended to design other flexible free-standing metal germanate nanocomposite anode materials.

  10. Flexible and free-standing ternary Cd2GeO4 nanowire/graphene oxide/CNT nanocomposite film with improved lithium-ion battery performance

    Science.gov (United States)

    Wang, Linlin; Zhang, Xiaozhu; Shen, Guozhen; Peng, Xia; Zhang, Min; Xu, Jingli

    2016-03-01

    To realize flexible lithium-ion batteries (LIBs), the design of flexible electrode/current collector materials with high mechanical flexibility, superior conductivity and excellent electrochemical performance and electrical stability are highly desirable. In this work, we developed a new ternary Cd2GeO4 nanowire/graphene oxide/carbon nanotube nanocomposite (Cd2GeO4 NW/GO/CNT) film electrode. Benefiting from the efficient combination of GO and Cd2GeO4 NWs, our Cd2GeO4 NW/GO/CNT composite film exhibits a capacity of 784 mA h g-1 after 30 cycles at 200 mA g-1, which is 2.7 times higher than that of Cd2GeO4 NW/CNT film (290 mA h g-1). At a higher rate of 400 mA g-1 and 1 A g-1, the Cd2GeO4 NW/GO/CNT film delivers a stable capacity of 617 and 397 mA h g-1, respectively. Even at 2.5 A g-1, it still exhibits a high rate capacity of 180 mA h g-1. The flexible Cd2GeO4 NW/GO/CNT film clearly demonstrates good cycling stability and rate performance for anode materials in LIBs. This route may be extended to design other flexible free-standing metal germanate nanocomposite anode materials.

  11. Transition Helmholtz free energy, entropy, and heat capacity of free-standing smectic films in water: a mean-field treatment.

    Science.gov (United States)

    Śliwa, Izabela; Zakharov, A V

    2014-11-21

    Using the extended McMillan's mean field approach with anisotropic forces a study of both the structural and thermodynamic properties of free-standing smectic film (FSSF) in water on heating to the isotropic temperature is carried out numerically. By solving the self-consistent nonlinear equations for the order parameters, we obtained that the smectic-A-isotropic (AI) transition occurs through the series of layer-thinning transitions causing the films to thin in the stepwise manner as the temperature is increased above the bulk smectic-A-isotropic temperature TAI(bulk). With enhanced pair interactions in the bounding layers, the smectic-isotropic transition corresponds to smectic melting of the central layers. The effects of surface "enhanced" pair interactions in the bounding layers and of film thickness on the orientational and translational order parameters, the Helmholtz free energy and entropy, as well as the temperature dependence of the heat capacity of FSSFs, have also been investigated. Reasonable agreement between the theoretically predicted and the experimentally obtained - by means of optical microscopy and ellipsometry techniques - data of the temperature when the thin decylcyanobiphenyl smectic film immersing in water ruptures has been obtained.

  12. A Metal-Free, Free-Standing, Macroporous Graphene@g-C₃N₄ Composite Air Electrode for High-Energy Lithium Oxygen Batteries.

    Science.gov (United States)

    Luo, Wen-Bin; Chou, Shu-Lei; Wang, Jia-Zhao; Zhai, Yu-Chun; Liu, Hua-Kun

    2015-06-01

    The nonaqueous lithium oxygen battery is a promising candidate as a next-generation energy storage system because of its potentially high energy density (up to 2-3 kW kg(-1)), exceeding that of any other existing energy storage system for storing sustainable and clean energy to reduce greenhouse gas emissions and the consumption of nonrenewable fossil fuels. To achieve high energy density, long cycling stability, and low cost, the air electrode structure and the electrocatalysts play important roles. Here, a metal-free, free-standing macroporous graphene@graphitic carbon nitride (g-C3N4) composite air cathode is first reported, in which the g-C3N4 nanosheets can act as efficient electrocatalysts, and the macroporous graphene nanosheets can provide space for Li2O2 to deposit and also promote the electron transfer. The electrochemical results on the graphene@g-C3N4 composite air electrode show a 0.48 V lower charging plateau and a 0.13 V higher discharging plateau than those of pure graphene air electrode, with a discharge capacity of nearly 17300 mA h g(-1)(composite) . Excellent cycling performance, with terminal voltage higher than 2.4 V after 105 cycles at 1000 mA h g(-1)(composite) capacity, can also be achieved. Therefore, this hybrid material is a promising candidate for use as a high energy, long-cycle-life, and low-cost cathode material for lithium oxygen batteries.

  13. Analysis of the AlGaN/GaN vertical bulk current on Si, sapphire, and free-standing GaN substrates

    Energy Technology Data Exchange (ETDEWEB)

    Perez-Tomas, A.; Fontsere, A.; Llobet, J. [IMB-CNM-CSIC, Campus UAB, 08193 Bellaterra, Barcelona, CAT (Spain); Placidi, M. [IREC, Jardins Dones de Negre 1, 08930 Sant Adria de Besos, Barcelona (Spain); Rennesson, S.; Chenot, S.; Moreno, J. C.; Cordier, Y. [CRHEA-CNRS, Rue Bernard Gregory, Sophia Antipolis, 06560 Valbonne (France); Baron, N. [CRHEA-CNRS, Rue Bernard Gregory, Sophia Antipolis, 06560 Valbonne (France); PICOGIGA International, Pl M. Rebuffat, Courtaboeuf 7, 91140 Villejust (France)

    2013-05-07

    The vertical bulk (drain-bulk) current (I{sub db}) properties of analogous AlGaN/GaN hetero-structures molecular beam epitaxially grown on silicon, sapphire, and free-standing GaN (FS-GaN) have been evaluated in this paper. The experimental I{sub db} (25-300 Degree-Sign C) have been well reproduced with physical models based on a combination of Poole-Frenkel (trap assisted) and hopping (resistive) conduction mechanisms. The thermal activation energies (E{sub a}), the (soft or destructive) vertical breakdown voltage (V{sub B}), and the effect of inverting the drain-bulk polarity have also been comparatively investigated. GaN-on-FS-GaN appears to adhere to the resistive mechanism (E{sub a} = 0.35 eV at T = 25-300 Degree-Sign C; V{sub B} = 840 V), GaN-on-sapphire follows the trap assisted mechanism (E{sub a} = 2.5 eV at T > 265 Degree-Sign C; V{sub B} > 1100 V), and the GaN-on-Si is well reproduced with a combination of the two mechanisms (E{sub a} = 0.35 eV at T > 150 Degree-Sign C; V{sub B} = 420 V). Finally, the relationship between the vertical bulk current and the lateral AlGaN/GaN transistor leakage current is explored.

  14. Facile fabrication of transparent TiO2-C@TiO2-C free-standing film for visible-light photocatalytic application

    Science.gov (United States)

    Hu, Luyang; Zhang, Yumin; Zhang, Shanmei; Li, Benxia

    2017-02-01

    A transparent TiO2-C@TiO2-C free-standing film has been synthesized by two-step hydrothermal method and subsequent thermal annealing. The chemical composition and morphological features of the TiO2-C@TiO2-C film are characterized using X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy and N2 adsorption-desorption measurement. The results indicate that the flower-like micro/nanostructure TiO2-C particle layers are intimately inhered to porous TiO2-C fibers. The fibers in film are interconnected each other to form a three-dimensional reticulate microstructure, and exhibit intense visible light absorption and high adsorptivity of dye molecules. The interaction between TiO2 and its surface carbon layer in TiO2-C particle promotes the generation of Ti-O-C bonds, which leads to effective charge transfer. Under visible-light irradiation, TiO2-C@TiO2-C film presents enhanced photocatalytic activity for degradation of methylene blue. This work may provide a new viewpoint for designing transparent photocatalytic film for promising applications in heterogeneous photocatalysis.

  15. Kinnisvarafirmade TOP 90

    Index Scriptorium Estoniae

    2002-01-01

    TOP 90. Kinnisvara valdkondade TOP 5. Käibe TOP 30. Käibe kasvu TOP 30. Rentaabluse TOP 30. Kasumi TOP 30. Kasumi kasvu TOP 30. Varade tootlikkuse TOP 30. Kinnisvarafirmade üldandmed. Kinnisvarafirmade finantsandmed

  16. Kinnisvarafirmade TOP 90

    Index Scriptorium Estoniae

    2002-01-01

    TOP 90. Kinnisvara valdkondade TOP 5. Käibe TOP 30. Käibe kasvu TOP 30. Rentaabluse TOP 30. Kasumi TOP 30. Kasumi kasvu TOP 30. Varade tootlikkuse TOP 30. Kinnisvarafirmade üldandmed. Kinnisvarafirmade finantsandmed

  17. A facile and general preparation of high-performance noble-metal-based free-standing nanomembranes by a reagentless interfacial self-assembly strategy

    Science.gov (United States)

    Wu, Haoxi; He, Haili; Zhai, Yujuan; Li, Haijuan; Lai, Jianping; Jin, Yongdong

    2012-10-01

    As a simple and flexible 2D platform, the water-air interface is envisioned as an environmentally-friendly approach to prepare ultrathin free-standing nanomembranes (FNMs) of monolayered nanoparticles of interest via interfacial self-assembly. However, attempts so far have been rather rare due to the lack of efficient methods. In this article, we report on a facile and general strategy for fabrication of a family of noble metal-based FNMs by a simple and reagentless interfacial self-assembly tactics to prepare functional (plasmonic or catalytic) FNMs, such as Au, Ag, Pd, Pt-FNMs and their bimetallic hybrids, Ag/Au-FNMs and Pd/Pt-FNMs. The organic solvent-free process, varying somewhat from metal to metal only in precursors, reducing agents and dosage of reagents used, is found to be a general phenomenon and ligand-independent (irrespective of the monolayer quality of the resulting FNMs), allowing the growth of high-quality noble metal-based FNMs with well-defined nanoparticulate and monolayer morphology as large as several square centimeters. Heat treatment (boiling) is performed to accelerate the formation of FNMs within 15 min. More significantly, the as-prepared plasmonic Au-FNMs acting as a SERS substrate show a superior activity; whereas the resulting catalytic Pd-FNMs, except for their excellent ethanol electrooxidation performance, exhibit higher electrocatalytic activity for formic acid oxidation than commercial catalysts.As a simple and flexible 2D platform, the water-air interface is envisioned as an environmentally-friendly approach to prepare ultrathin free-standing nanomembranes (FNMs) of monolayered nanoparticles of interest via interfacial self-assembly. However, attempts so far have been rather rare due to the lack of efficient methods. In this article, we report on a facile and general strategy for fabrication of a family of noble metal-based FNMs by a simple and reagentless interfacial self-assembly tactics to prepare functional (plasmonic or

  18. Hierarchical MoS2 nanosheet/active carbon fiber cloth as a binder-free and free-standing anode for lithium-ion batteries

    Science.gov (United States)

    Wang, Chao; Wan, Wang; Huang, Yunhui; Chen, Jitao; Zhou, Heng Hui; Zhang, Xin Xiang

    2014-04-01

    Owing to the layered structure and high theoretical capacity, MoS2 has attracted more and more interest as a potential anode material for lithium-ion batteries. However, it suffers from rapid capacity decay and low rate capability. In this work, we introduce a novel hierarchical material consisting of ultrathin MoS2 nanosheets grown on the surface of an active carbon fiber (ACF) cloth fabricated by a facile morphogenetic process. The ACF cloth acts as both a template and a stabilizer. The obtained MoS2/ACF cloth composite possesses hierarchical porosity and an interconnected framework. Serving as a free-standing and binder-free anode, it shows high specific capacity and excellent reversibility. A discharge capacity as high as 971 mA h g-1 is attained at a current density of 0.1 A g-1, and the capacity fade is only 0.15% per cycle within 90 cycles. Even after 200 cycles at a high current density of 0.5 A g-1, the composite still shows a capacity of 418 mA h g-1. The superior electrochemical performance of MoS2/ACF can be attributed to its robust structure and to the synergistic effects of ultrathin MoS2 nanosheets and ACF. This single-component anode that we propose benefits from a simplified electrode preparation process. The morphogenetic strategy used for the material production is facile but effective, and can be extended to prepare other metal sulfides with elaborate textural characteristics.Owing to the layered structure and high theoretical capacity, MoS2 has attracted more and more interest as a potential anode material for lithium-ion batteries. However, it suffers from rapid capacity decay and low rate capability. In this work, we introduce a novel hierarchical material consisting of ultrathin MoS2 nanosheets grown on the surface of an active carbon fiber (ACF) cloth fabricated by a facile morphogenetic process. The ACF cloth acts as both a template and a stabilizer. The obtained MoS2/ACF cloth composite possesses hierarchical porosity and an

  19. High-Efficiency Robust Free-Standing Composited Phosphor Films with 2D and 3D Nanostructures for High-Power Remote White LEDs.

    Science.gov (United States)

    Lai, Chun-Feng; Li, Jia-Sian; Shen, Chung-Wen

    2017-02-08

    This study demonstrated that combined free-standing quasi-amorphous/micropattern (QA/MP) composited resin film-assisted phosphor films enhanced the mechanical robustness, luminous efficacy, color rendering index (CRI), and special R9 of high-power remote warm white light-emitting diodes (WLEDs). Introducing QA/MP nanostructures into phosphor film resulted in high efficiency of remote warm WLEDs with low phosphor thickness (approximately 25 μm) and reduced the correlated color temperature (CCT) from cold white light (approximately 5565 K) to warm white light (approximately 3178 K). The QA/MP composited phosphor films (CPFs) used for high-power remote WLEDs enhanced the CRI and special R9 and reduced the CCT. These results were attributed to that QA resin film reflected the blue light and re-emitted the added red emission. CIR (84), a natural warm white CCT (3178 K), and an acceptable luminous efficacy (102.5 lm/W) were achieved from the QA/MP CPFs of high-power remote WLEDs during operation at an input power of 10 W (current of 700 mA). The bending strength of QA/MP CPFs at approximately 112 N was significantly enhanced by 40% compared with that of flat CPFs. The QA/MP CPFs applied to high-power remote WLEDs exhibited good thermal and optical stability. QA/MP CPFs were also conducted to a reliability analysis (RA), in which temperature of 85 °C and relative humidity of 85% were applied for 3288 h. Lumen maintenance was degraded by 8% during RA test because the transmittance of trimethylolopropane ethoxylate triacrylate resins was degraded under high temperature. Overall, we implemented a reliable and inexpensive technology that can potentially reduce phosphor thickness, address the out-bin problems of defective WLEDs, and fabricate flat-panel lighting source with good lighting quality.

  20. Slow dynamics and glass transition in simulated free-standing polymer films: a possible relation between global and local glass transition temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Peter, S [Institut Charles Sadron, 6 rue Boussingault, 67083 Strasbourg Cedex (France); Meyer, H [Institut Charles Sadron, 6 rue Boussingault, 67083 Strasbourg Cedex (France); Baschnagel, J [Institut Charles Sadron, 6 rue Boussingault, 67083 Strasbourg Cedex (France); Seemann, R [Max Planck Institute for Dynamics and Self-Organization, D-37018 Goettingen (Germany)

    2007-05-23

    We employ molecular dynamics simulations to explore the influence that the surface of a free-standing polymer film exerts on its structural relaxation when the film is cooled toward the glass transition. Our simulations are concerned with the features of a coarse-grained bead-spring model in a temperature regime above the critical temperature T{sub c} of mode-coupling theory. We find that the film dynamics is spatially heterogeneous. Monomers at the free surface relax much faster than they would in the bulk at the same temperature T. The fast relaxation of the surface layer continuously turns into bulk-like relaxation with increasing distance y from the surface. This crossover remains smooth for all T, but its range grows on cooling. We show that it is possible to associate a gradient in critical temperatures T{sub c}(y) with the gradient in the relaxation dynamics. This finding is in qualitative agreement with experimental results on supported polystyrene (PS) films (Ellison and Torkelson 2003 Nat. Mater. 2 695). Furthermore we show that the y dependence of T{sub c}(y) can be expressed in terms of the depression of T{sub c}(h)-the global T{sub c} for a film of thickness h-if we assume that T{sub c}(h) is the arithmetic mean of T{sub c}(y) and parameterize the depression of T{sub c}(h) by T{sub c}(h) = T{sub c}/(1+h{sub 0}/h), a formula suggested by Herminghaus et al (2001 Eur. Phys. J. E 5 531) for the reduction of the glass transition temperature in supported PS films. We demonstrate the validity of this formula by comparing our simulation results to results from other simulations and experiments.

  1. Top studies

    Energy Technology Data Exchange (ETDEWEB)

    T. Dorigo

    2003-01-02

    The top quark, discovered in 1994 at the Tevatron, has proven a very interesting particle. Its characteristics allow both to perform stringent tests of electroweak theory, and to search for new physics through a deviation from standard model predictions for several of its peculiar properties. I will review the status of top physics and briefly describe the potential of experiments of the near future.

  2. Mixed P25 nanoparticles and large rutile particles as a top scattering layer to enhance performance of nanocrystalline TiO{sub 2} based dye-sensitized solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Xiaohua, E-mail: mksxh@163.com; Zhou, Xin; Xu, Yalong; Sun, Panpan; Huang, Niu; Sun, Yihua

    2015-05-15

    Graphical abstract: - Highlights: • Mixed P25 nanoparticles and large rutile particles were employed to form a top scattering layer. • The top scattering layer exhibits superior light scattering effect. • The bottom nanocrystalline TiO{sub 2} layer can make good use of the back-scattered light. • Bilayer TiO{sub 2} photoanode shows faster interfacial electron transfer and slower charge recombination process. • Bilayer photoanode enhances the DSSC efficiency by a factor of 25%. - Abstract: Herein, we report a bilayer TiO{sub 2} photoanode composed of nanocrystalline TiO{sub 2} (NCT) bottom layer and mixed P25 nanoparticles and large rutile particles (PR) top scattering layer. The present structure performs well in solar light harvesting which is mainly attributed to the fact that the top scattering layer exhibits superior light scattering effect and meanwhile the NCT bottom layer with large dye-loading capacity can make better use of the back-scattered light. Moreover, electrochemical impedance spectroscopy and open circuit voltage decay measurements demonstrate that DSSC based on bilayer photoanode shows faster interfacial electron transfer and slower charge recombination process than that based on NCT monolayer photoanode. These advantages render the DSSCs based on NCT-PR bilayer photoanode exhibiting superior performance under AM1.5G simulated solar irradiation. As an example, by tuning mass ratio between P25 nanoparticles and large rutile particles in the top scattering layer, the DSSC based on NCT-PR bilayer photoanode exhibits an optimum solar energy conversion efficiency of 9.0%, which is about 1.25 times higher than that of monolayer NCT device (7.2%) with the same film thickness.

  3. In-Situ Fabrication of a Self-Aligned Selective Emitter Silicon Solar Cell Using the Gold Top Contacts To Facilitate the Synthesis of a Nanostructured Black Silicon Antireflective Layer Instead of an External Metal Nanoparticle Catalyst.

    Science.gov (United States)

    Lu, Yen-Tien; Barron, Andrew R

    2015-06-10

    Silicon solar cells with nanopore-type black silicon (b-Si) antireflection (AR) layers and self-aligned selective emitter (SE) are reported in which the b-Si structure is prepared without the traditional addition of a nanoparticle (NP) catalyst. The contact-assisted chemical etching (CACE) method is reported here for the first time, in which the metal top contacts on silicon solar cell surfaces function as the catalysts for b-Si fabrication and the whole etching process can be done in minutes at room temperature. The CACE method is based on the metal-assisted chemical etching (MACE) solution but without or metal precursor in the Si etchant (HF:H2O2:H2O), and the Au top contacts, or catalysts, are not removed from the solar cell surface after the etching. The effects of etching time, HF and H2O2 concentration, and the HF:H2O2 ratio on the b-Si morphology, surface reflectivity, and solar cell efficiency have been investigated. Higher [HF] and [H2O2] with longer etching time cause collapse of the b-Si nanoporous structure and penetration of the p-n junctions, which are detrimental to the solar cell efficiency. The b-Si solar cell fabricated with the HF:H2O2:H2O volume ratio of 3:3:20 and a 3 min etch time shows the highest efficiency 8.99% along with a decrease of reflectivity from 36.1% to 12.6% compared to that of the nonetched Si solar cell.

  4. Hybrid 2D photonic crystal-assisted Lu3Al5O12:Ce ceramic-plate phosphor and free-standing red film phosphor for white LEDs with high color-rendering index.

    Science.gov (United States)

    Park, Hoo Keun; Oh, Ji Hye; Kang, Heejoon; Zhang, Jian; Do, Young Rag

    2015-03-04

    This paper reports the combined optical effects of a two-dimensional (2D) SiNx photonic crystal layer (PCL)-assisted Lu3Al5O12:Ce (LuAG:Ce) green ceramic-plate phosphor (CPP) and a free-standing (Sr,Ca)AlSiN3:Eu red film phosphor to enhance luminous efficacy, color rendering index (CRI), and special CRI (R9) of LuAG:Ce CPP-capped white light-emitting diodes (LEDs) for high-power white LEDs at 350 mA. By introducing the 2D SiNx PCL, the luminous efficacy was improved by a factor of 1.25 and 1.15 compared to that of the conventional flat CPP-capped LED and the thickness-increased CPP-capped LED (with a thickness of 0.15 mm), respectively, while maintaining low color-rendering properties. The combining of the free-standing red film phosphor in the flat CPP-capped, the 2D PCL-assisted CPP-capped, and the thickness-increased CPP-capped LEDs led to enhancement of the CRI and the special CRI (R9); it also led to a decrease of the correlated color temperature (CCT) due to broad wavelength coverage via the addition of red emission. High CRI (94), natural white CCT (4450 K), and acceptable luminous efficacy (71.1 lm/W) were attained from the 2D PCL-assisted LuAG:Ce CPP/free-standing red film phosphor-based LED using a red phosphor concentration of 7.5 wt %. It is expected that the combination of the 2D PCL and the free-standing red film phosphor will be a good candidate for achieving a high-power white CPP-capped LED with excellent CRI.

  5. Top couplings and top partners

    OpenAIRE

    2013-01-01

    We review the model-independent description of the couplings of the top quark to the Higgs and gauge bosons in theories beyond the Standard Model. Then we examine these couplings in the case of arbitrary heavy vector-like quarks mixing with the third family. We also discuss the couplings of these top partners, and comment on implications for LHC searches.

  6. Põllumajandustootjate TOP 50

    Index Scriptorium Estoniae

    2006-01-01

    Põllumajandustootjate TOP. Vt. samas: Käibe TOP 10; Käibe kasvu TOP 10; Majandustegevuse kasumi TOP 10; Kasumi kasvu TOP 10; Rentaabluse TOP 10; Omakapitali tootlikkuse TOP 10; Põllumajandustootjate üld- ja finantsandmed

  7. Teedeehitusfirmade TOP 24

    Index Scriptorium Estoniae

    2006-01-01

    Teedeehitusfirmade TOP. Vt. samas: Käibe TOP 10; Käibe kasvu TOP 10; Kasumi TOP 10; Kasumi Kasvu TOP 10; Rentaabluse TOP 10; Omakapitali tootlikkuse TOP 10; Teedeehitusfirmade üld- ja finantsandmed

  8. Ehitusmaterjalitootjate TOP 95

    Index Scriptorium Estoniae

    2006-01-01

    Ehitusmaterjalitootjate TOP. Vt. samas: Käibe TOP 10; Käibe kasvu TOP 10; Kasumi TOP 10; Kasumi kasvu TOP 10; Rentaabluse TOP 10; Omakapitali tootlikkuse TOP 10; Ehitusmaterjalitootjate üld- ja finantsandmed

  9. Telekommunikatsiooni TOP aastal 2003

    Index Scriptorium Estoniae

    2004-01-01

    Telekommunikatsiooni TOP aastal 2003. Käibe TOP 10. Käibe kasvu TOP 10. Rentaabluse TOP 10. Kasumi TOP 10. Kasumi kasvu TOP 10. Omakapitali tootlikkuse TOP 10. Telekommunikatsioonifirmade üldandmed. Telekommunikatsioonifirmade finantsandmed

  10. Audiitorfirmade TOP 50

    Index Scriptorium Estoniae

    2004-01-01

    Audiitorfirmade TOP 50; Käibe TOP 10; Käibe kasvu TOP 10; Rentaabluse TOP 10; Kasumi TOP 10; Kasumi kasvu TOP 10; Omakapitali tootlikkuse TOP 10; Audiitorfirmade finantsandmed; Audiitorfirmade üldandmed

  11. Teedeehitusfirmade TOP 24

    Index Scriptorium Estoniae

    2006-01-01

    Teedeehitusfirmade TOP. Vt. samas: Käibe TOP 10; Käibe kasvu TOP 10; Kasumi TOP 10; Kasumi Kasvu TOP 10; Rentaabluse TOP 10; Omakapitali tootlikkuse TOP 10; Teedeehitusfirmade üld- ja finantsandmed

  12. Koolitusfirmade TOP 50

    Index Scriptorium Estoniae

    2006-01-01

    Koolitusfirmade TOP. Vt. samas: Käibe TOP 10; Käibe kasvu TOP 10; Majandustegevuse kasumi TOP 10; Kasumi kasvu TOP 10; Rentaabluse TOP 10; Omakapitali tootlikkuse TOP 10; Koolitusfirmade üld- ja finantsandmed

  13. Top mesons

    Energy Technology Data Exchange (ETDEWEB)

    Fabiano, N. [Perugia, Univ. (Italy)]|[INFN, Frascati (Italy). Laboratori Nazionali di Frascati

    1997-03-01

    The possibility of formation for a bound state of a t quark and a lighter one is investigated using potential model predictions and heavy quark effective theory approach. Resulting estimates for the 1S-2S splitting of the energy levels are compared to the total top decay width {Gamma}{sub t}. As for the case of toponium, their conclusions show that the probability of formation for T-mesons is negligibly small due to the high top mass value.

  14. The impact of surface chemistry on the performance of localized solar-driven evaporation system

    Science.gov (United States)

    Yu, Shengtao; Zhang, Yao; Duan, Haoze; Liu, Yanming; Quan, Xiaojun; Tao, Peng; Shang, Wen; Wu, Jianbo; Song, Chengyi; Deng, Tao

    2015-09-01

    This report investigates the influence of surface chemistry (or wettability) on the evaporation performance of free-standing double-layered thin film on the surface of water. Such newly developed evaporation system is composed of top plasmonic light-to-heat conversion layer and bottom porous supporting layer. Under solar light illumination, the induced plasmonic heat will be localized within the film. By modulating the wettability of such evaporation system through the control of surface chemistry, the evaporation rates are differentiated between hydrophilized and hydrophobized anodic aluminum oxide membrane-based double layered thin films. Additionally, this work demonstrated that the evaporation rate mainly depends on the wettability of bottom supporting layer rather than that of top light-to-heat conversion layer. The findings in this study not only elucidate the role of surface chemistry of each layer of such double-layered evaporation system, but also provide additional design guidelines for such localized evaporation system in applications including desalination, distillation and power generation.

  15. The impact of surface chemistry on the performance of localized solar-driven evaporation system.

    Science.gov (United States)

    Yu, Shengtao; Zhang, Yao; Duan, Haoze; Liu, Yanming; Quan, Xiaojun; Tao, Peng; Shang, Wen; Wu, Jianbo; Song, Chengyi; Deng, Tao

    2015-09-04

    This report investigates the influence of surface chemistry (or wettability) on the evaporation performance of free-standing double-layered thin film on the surface of water. Such newly developed evaporation system is composed of top plasmonic light-to-heat conversion layer and bottom porous supporting layer. Under solar light illumination, the induced plasmonic heat will be localized within the film. By modulating the wettability of such evaporation system through the control of surface chemistry, the evaporation rates are differentiated between hydrophilized and hydrophobized anodic aluminum oxide membrane-based double layered thin films. Additionally, this work demonstrated that the evaporation rate mainly depends on the wettability of bottom supporting layer rather than that of top light-to-heat conversion layer. The findings in this study not only elucidate the role of surface chemistry of each layer of such double-layered evaporation system, but also provide additional design guidelines for such localized evaporation system in applications including desalination, distillation and power generation.

  16. Architectural Tops

    Science.gov (United States)

    Mahoney, Ellen

    2010-01-01

    The development of the skyscraper is an American story that combines architectural history, economic power, and technological achievement. Each city in the United States can be identified by the profile of its buildings. The design of the tops of skyscrapers was the inspiration for the students in the author's high-school ceramic class to develop…

  17. Top Earners

    DEFF Research Database (Denmark)

    Badel, Alejandro; Daly, Moira; Huggett, Mark

    with age and (4) the real earnings growth rate over the working lifetime is larger for higher lifetime earners. Compared to the US, we find that Denmark and Sweden have a more compressed earnings and wage rate distribution above the median and a smaller real earnings growth rates for top lifetime earners....

  18. Top tippler

    Energy Technology Data Exchange (ETDEWEB)

    Bedingham, A. [Bluff Mechanical Appliance (South Africa)

    2004-07-01

    The paper discusses the difference an open top container tippler can make. The container tippler allows a container to be transported by road or rail to a terminal where they can be stored in block stacks at high storage densities and then loaded directly to ship or stockpile. The article describes the design of a container tippler system for BMA by Dynamika Materials Handling Pty Ltd. at the Port of Durban, South Africa. 4 photos.

  19. Autotranspordifirmade TOP 100

    Index Scriptorium Estoniae

    2006-01-01

    Ilmunud ka: Delovõje Vedomosti : Transport i Logistika 29. nov. lk. 10-11. Autofirmade TOP 100. Vt. samas: Käibe TOP 10; Käibe kasvu TOP 10; Majandustegevuse kasumi TOP 10; Kasumi kasvu TOP 10; Rentaabluse TOP 10; Omakapitali tootlikkuse TOP 10; Autotranspordifirmade üld- ja finantsandmed. Delovõje Vedomosti : Transport i Logistika sisaldab tabelit Autofirmade TOP 100

  20. Autotranspordifirmade TOP 100

    Index Scriptorium Estoniae

    2006-01-01

    Ilmunud ka: Delovõje Vedomosti : Transport i Logistika 29. nov. lk. 10-11. Autofirmade TOP 100. Vt. samas: Käibe TOP 10; Käibe kasvu TOP 10; Majandustegevuse kasumi TOP 10; Kasumi kasvu TOP 10; Rentaabluse TOP 10; Omakapitali tootlikkuse TOP 10; Autotranspordifirmade üld- ja finantsandmed. Delovõje Vedomosti : Transport i Logistika sisaldab tabelit Autofirmade TOP 100

  1. Koolitusfirmade TOP aastal 2007

    Index Scriptorium Estoniae

    2008-01-01

    Koolitusfirmade TOP. Vt. samas: Käibe TOP 10; Käibekasvu TOP 10; Kasumi TOP 10; Kasumi kasvu TOP 10; Rentaabluse TOP 10; Omakapitali tootlikkuse TOP 10; Signe Sillasoo. Invicta tahab lähiaastail laieneda Eestis ja mujalgi; Ketlin Priilinn. Addenda kasutas ära majanduse soodsa seisu. Kommenteerib Heli Sõmer. Juhtide hoiakute muutmisega tõus esikolmikusse

  2. Autotranspordi TOP aastal 2007

    Index Scriptorium Estoniae

    2008-01-01

    TOP 50. Vt. samas: Käibe TOP 10; Käibe kasvu TOP 10; Kasumi TOP 10; Kasumi kasvu TOP 10; Rentaabluse TOP 10; Omakapitali tootlikkuse TOP 10; Marika Roomere. Täisteenuse pakkumine kergitas tulemusi; Jupiter Plus otsib järjest uusi kasvuvõimalusi; EST-Trans Kaubaveod teenib kasumit toiduvedamisega

  3. Ehitusmaterjalitootjate TOP 70

    Index Scriptorium Estoniae

    2005-01-01

    Ilmunud ka: Delovõje Vedomosti : Stroitelstvo 28. sept. lk. 2. Ehitusmaterjalitootjate TOP 70; Käibe TOP 10; Kasumi TOP 10; Käibe kasvu TOP 10; Kasumi kasvu TOP 10; Rentaabluse TOP 10; Omakapitali tootlikkuse TOP; Ehitusmaterjalitootjate üld- ja finantsandmed

  4. Koolitusfirmade TOP aastal 2007

    Index Scriptorium Estoniae

    2008-01-01

    Koolitusfirmade TOP. Vt. samas: Käibe TOP 10; Käibekasvu TOP 10; Kasumi TOP 10; Kasumi kasvu TOP 10; Rentaabluse TOP 10; Omakapitali tootlikkuse TOP 10; Signe Sillasoo. Invicta tahab lähiaastail laieneda Eestis ja mujalgi; Ketlin Priilinn. Addenda kasutas ära majanduse soodsa seisu. Kommenteerib Heli Sõmer. Juhtide hoiakute muutmisega tõus esikolmikusse

  5. Audiitorfirmade TOP aastal 2007

    Index Scriptorium Estoniae

    2008-01-01

    Audiitorfirmade TOP 51. Vt. samas: Urve Vilk. Audiitoriteni pole majanduslangus jõudnud; Intervjuu I.S. Audiitorteenuste OÜ omaniku Irina Somovaga; Käibe TOP 10; Käibe kasvu TOP 10; Kasumi TOP 10; Kasumi kasvu TOP 10; Rentaabluse TOP 10; Omakapitali tootlikkuse TOP 10

  6. Autotranspordi TOP aastal 2007

    Index Scriptorium Estoniae

    2008-01-01

    TOP 50. Vt. samas: Käibe TOP 10; Käibe kasvu TOP 10; Kasumi TOP 10; Kasumi kasvu TOP 10; Rentaabluse TOP 10; Omakapitali tootlikkuse TOP 10; Marika Roomere. Täisteenuse pakkumine kergitas tulemusi; Jupiter Plus otsib järjest uusi kasvuvõimalusi; EST-Trans Kaubaveod teenib kasumit toiduvedamisega

  7. Audiitorfirmade TOP aastal 2007

    Index Scriptorium Estoniae

    2008-01-01

    Audiitorfirmade TOP 51. Vt. samas: Urve Vilk. Audiitoriteni pole majanduslangus jõudnud; Intervjuu I.S. Audiitorteenuste OÜ omaniku Irina Somovaga; Käibe TOP 10; Käibe kasvu TOP 10; Kasumi TOP 10; Kasumi kasvu TOP 10; Rentaabluse TOP 10; Omakapitali tootlikkuse TOP 10

  8. Ekspedeerimisfirmade TOP 2004

    Index Scriptorium Estoniae

    2005-01-01

    Ilmunud ka: Delovõje Vedomosti : Transport i Logistika 30. nov. lk. 11. Ekspedeerimisfirmade TOP 55; Käibe TOP 15; Käibe kasvu TOP 15; Majandustegevuse kasumi TOP 15; Kasumi kasvu TOP 15; Rentaabluse TOP 15; Omakapitali tootlikkuse TOP 15; Ekspedeerimisfirmade üld- ja finantsandmed

  9. Koolitusfirmade TOP 50

    Index Scriptorium Estoniae

    2005-01-01

    Koolitusfirmade TOP 50; Käibe TOP 15; Käibe kasvu TOP 15; Kasumi TOP 15; Kasumi kasvu TOP 15; Rentaabluse TOP 15; Omakapitali tootlikkuse TOP 15; Koolitusfirmade üld- ja finantsandmed; Kõrgkoolide ülevaade; Kutsekoolide ülevaade

  10. Top reconstruction and boosted top experimental overview

    CERN Document Server

    Skinnari, Louise

    2015-01-01

    An overview of techniques used to reconstruct resolved and boosted top quarks is presented. Techniques for resolved top quark reconstruction include kinematic likelihood fitters and pseudo- top reconstruction. Many tools and methods are available for the reconstruction of boosted top quarks, such as jet grooming techniques, jet substructure variables, and dedicated top taggers. Different techniques as used by ATLAS and CMS analyses are described and the performance of different variables and top taggers are shown.

  11. Structural and magnetic characterization of large area, free-standing thin films of magnetic ion intercalated dichalcogenides Mn0.25TaS2 and Fe0.25TaS2

    Science.gov (United States)

    Danz, Th; Liu, Q.; Zhu, X. D.; Wang, L. H.; Cheong, S. W.; Radu, I.; Ropers, C.; Tobey, R. I.

    2016-09-01

    Free-standing thin films of magnetic ion intercalated transition metal dichalcogenides are produced using ultramicrotoming techniques. Films of thicknesses ranging from 30 nm to 250 nm were achieved and characterized using transmission electron diffraction and x-ray magnetic circular dichroism. Diffraction measurements visualize the long range crystallographic ordering of the intercalated ions, while the dichroism measurements directly assess the orbital contributions to the total magnetic moment. We thus verify the unquenched orbital moment in Fe0.25TaS2 and measure the fully quenched orbital contribution in Mn0.25TaS2. Such films can be used in a wide variety of ultrafast x-ray and electron techniques that benefit from transmission geometries, and allow measurements of ultrafast structural, electronic, and magnetization dynamics in space and time.

  12. In Situ Coupling of Strung Co4N and Intertwined N-C Fibers toward Free-Standing Bifunctional Cathode for Robust, Efficient, and Flexible Zn-Air Batteries.

    Science.gov (United States)

    Meng, Fanlu; Zhong, Haixia; Bao, Di; Yan, Junmin; Zhang, Xinbo

    2016-08-17

    Flexible power sources with high energy density are crucial for the realization of next-generation flexible electronics. Theoretically, rechargeable flexible zinc-air (Zn-air) batteries could provide high specific energy, while their large-scale applications are still greatly hindered by high cost and resources scarcity of noble-metal-based oxygen evolution reaction (OER)/oxygen reduction reaction (ORR) electrocatalysts as well as inferior mechanical properties of the air cathode. Combining metallic Co4N with superior OER activity and Co-N-C with perfect ORR activity on a free-standing and flexible electrode could be a good step for flexible Zn-air batteries, while lots of difficulties need to be overcome. Herein, as a proof-of-concept experiment, we first propose a strategy for in situ coupling of strung Co4N and intertwined N-C fibers, by pyrolyzation of the novel pearl-like ZIF-67/polypyrrole nanofibers network rooted on carbon cloth. Originating from the synergistic effect of Co4N and Co-N-C and the stable 3D interconnected conductive network structure, the obtained free-standing and highly flexible bifunctional oxygen electrode exhibits excellent electrocatalytic activity and stability for both OER and ORR in terms of low overpotential (310 mV at 10 mA cm(-2)) for OER, a positive half-wave potential (0.8 V) for ORR, and a stable current density retention for at least 20 h, and especially, the obtained Zn-air batteries exhibit a low discharge-charge voltage gap (1.09 V at 50 mA cm(-2)) and long cycle life (up to 408 cycles). Furthermore, the perfect bendable and twistable and rechargeable properties of the flexible Zn-air battery particularly make it a potentially power portable and wearable electronic device.

  13. Measurement and simulation of top- and bottom-illuminated solar-blind AlGaN metal-semiconductor-metal photodetectors with high external quantum efficiencies

    Energy Technology Data Exchange (ETDEWEB)

    Brendel, Moritz, E-mail: moritz.brendel@fbh-berlin.de; Helbling, Markus; Knigge, Andrea; Brunner, Frank; Weyers, Markus [Ferdinand-Braun-Institut, Leibniz-Institut für Höchstfrequenztechnik (FBH), Gustav-Kirchhoff-Str. 4, 12489 Berlin (Germany)

    2015-12-28

    A comprehensive study on top- and bottom-illuminated Al{sub 0.5}Ga{sub 0.5}N/AlN metal-semiconductor-metal (MSM) photodetectors having different AlGaN absorber layer thickness is presented. The measured external quantum efficiency (EQE) shows pronounced threshold and saturation behavior as a function of applied bias voltage up to 50 V reaching about 50% for 0.1 μm and 67% for 0.5 μm thick absorber layers under bottom illumination. All experimental findings are in very good accordance with two-dimensional drift-diffusion modeling results. By taking into account macroscopic polarization effects in the hexagonal metal-polar +c-plane AlGaN/AlN heterostructures, new insights into the general device functionality of AlGaN-based MSM photodetectors are obtained. The observed threshold/saturation behavior is caused by a bias-dependent extraction of photoexcited holes from the Al{sub 0.5}Ga{sub 0.5}N/AlN interface. While present under bottom illumination for any AlGaN layer thickness, under top illumination this mechanism influences the EQE-bias characteristics only for thin layers.

  14. Jaekaubandusettevõtete TOP 70

    Index Scriptorium Estoniae

    2005-01-01

    Jaekaubandusettevõtete TOP 70; Käibe TOP 25; Kasumi TOP 25; Käibe kasvu TOP 20; Kasumi kasvu TOP 20; Rentaabluse TOP 20; Omakapitali tootlikkuse TOP 20; Jaekaubandusettevõtete üld- ja finantsandmed

  15. Arvutifirmade TOP 101 aastal 2004

    Index Scriptorium Estoniae

    2005-01-01

    Arvutifirmade TOP 101; Käibe TOP 20; Käibe kasvu TOP 15; Kasumi TOP 15; Rentaabluse TOP 20; Kasumi kasvu TOP 15; Omakapiali tootlikkuse TOP 15; Eesti arvutifirmade finantsandmed; Arvutifirmade üldandmed

  16. Jaekaubanduse TOP 100 aastal 2001

    Index Scriptorium Estoniae

    2002-01-01

    TOP 100. Käibe TOP 30. Käibe kasvu TOP 30. Kasumi TOP 30. Kasumi kasvu TOP 30. Rentaabluse TOP 30. Varade tootlikkuse TOP 30. Jaekaubandusettevõtete finantsseadmed. Jaekaubandusettevõtete üldandmed

  17. Jaekaubandusettevõtete TOP 70

    Index Scriptorium Estoniae

    2005-01-01

    Jaekaubandusettevõtete TOP 70; Käibe TOP 25; Kasumi TOP 25; Käibe kasvu TOP 20; Kasumi kasvu TOP 20; Rentaabluse TOP 20; Omakapitali tootlikkuse TOP 20; Jaekaubandusettevõtete üld- ja finantsandmed

  18. Jaekaubanduse TOP 100 aastal 2001

    Index Scriptorium Estoniae

    2002-01-01

    TOP 100. Käibe TOP 30. Käibe kasvu TOP 30. Kasumi TOP 30. Kasumi kasvu TOP 30. Rentaabluse TOP 30. Varade tootlikkuse TOP 30. Jaekaubandusettevõtete finantsseadmed. Jaekaubandusettevõtete üldandmed

  19. Autotranspordifirmade TOP 100 aastal 2002

    Index Scriptorium Estoniae

    2003-01-01

    TOP 100. Käibe TOP 15. Kasumi TOP 15. Rentaabluse TOP 15. Käibe kasvu TOP 15. Kasumi kasvu TOP 15. Omakapitali tootlikkuse TOP 15. Autotranspordifirmade finantsandmed. Autotranspordifirmade üldandmed

  20. Majutusasutuste TOP 40 aastal 2002

    Index Scriptorium Estoniae

    2003-01-01

    Majutusasutuste TOP 40 aastal 2002. Käibe TOP 40. Kasumi TOP 40. Käibe kasvu TOP 20. Kasumi kasvu TOP 20. Rentaabluse TOP 20. Omakapitali tootlikkuse TOP 20. Majutusasutuste üldandmed. Majutusasutuste finantsandmed

  1. Koolitusfirmade TOP 35 aastal 2002

    Index Scriptorium Estoniae

    2003-01-01

    Koolitusfirmade TOP 35. Käibe TOP 15. Käibe kasvu TOP 15. Kasumi TOP 15. Kasumi kasvu TOP 15. Rentaabluse TOP 15. Omakapitali tootlikkuse TOP 15. Koolitusfirmade finantsandmed. Koolitusfirmade üldandmed

  2. Audiitorfirmade TOP 50 aastal 2002

    Index Scriptorium Estoniae

    2003-01-01

    Audiitorfirmade TOP 50 aastal 2002. Käibe TOP 15. Kasumi TOP 15. Käibe kasvu TOP 15. Kasumi kasvu TOP 15. Rentaabluse TOP 15. Omakapitali tootlikkuse TOP 15. Audiitorfirmade üldandmed. Audiitorfirmade finantsandmed

  3. All inorganic semiconductor nanowire mesh for direct solar water splitting.

    Science.gov (United States)

    Liu, Bin; Wu, Cheng-Hao; Miao, Jianwei; Yang, Peidong

    2014-11-25

    The generation of chemical fuels via direct solar-to-fuel conversion from a fully integrated artificial photosynthetic system is an attractive approach for clean and sustainable energy, but so far there has yet to be a system that would have the acceptable efficiency, durability and can be manufactured at a reasonable cost. Here, we show that a semiconductor mesh made from all inorganic nanowires can achieve unassisted solar-driven, overall water-splitting without using any electron mediators. Free-standing nanowire mesh networks could be made in large scales using solution synthesis and vacuum filtration, making this approach attractive for low cost implementation.

  4. Preparation of free-standing graphene carbon membrane for gas separation%自支撑石墨烯炭膜的制备及气体分离性能

    Institute of Scientific and Technical Information of China (English)

    张生义; 李琳; 王春雷; 郑天赋; 孙亚明; 王同华

    2016-01-01

    Free-standing graphene carbon membrane with conch nacre structure was preparedvia carbonizing composite membrane of graphene oxide (GO) and polyamide acid (PAA) obtained by solvent evaporation method at 600℃. The morphology and structure were characterized by XRD and SEM. The permeation performance of CO2 and CH4 of free-standing graphene carbon membrane with different PAA solid content was investigated. The results indicated that GO was thermally reduced to graphene in graphene carbon membrane after carbonization, in which graphene layers were lamellar stacked and gaps between layers were filled with holes and carbon residue. Both CO2 permeability and ideal selectivity for the CO2/CH4 of graphene carbon membranes were enhanced with increasing PAA solid content. The CO2 flux of graphene carbon membrane was up to 824 barrer and the CO2/ CH4 ideal selectivity reached 38.9 simultaneously. The gas permeation channels of graphene carbon membrane were attributed to the lamellar stacked of graphene and carbon molecule sieve in graphene carbon membrane. This study opened up new opportunities to prepare the flexible free-standing graphene carbon membrane for gas separation.%通过溶剂蒸发法得到聚酰胺酸(PAA)与氧化石墨烯(GO)的复合石墨烯膜,并经600℃炭化制备了具有良好柔韧性的仿贝壳珍珠层结构的自支撑石墨烯炭膜。通过X射线衍射和场发射扫描电镜对薄膜微观结构进行表征,并测试不同PAA固含量制备的石墨烯炭膜对CO2和CH4的分离性能。结果表明,炭化后,GO被还原成石墨烯,呈层状堆叠,堆叠的层间填充了空穴和残炭;石墨烯炭膜的CO2渗透通量和CO2/CH4分离理想选择性随PAA加入量增加,CO2通量最高可达824 barrer,此时CO2/CH4理想选择性达38.9。石墨烯层骨架和碳分子筛构成石墨烯炭膜的气体传输通道,本研究成果为柔性自支撑气体分离炭膜的制备开辟了新思路。

  5. Analytical modelling and experimental verification of the three-dimensional current distribution on the top surface of silicon solar cells operating under concentrated sunlight

    Energy Technology Data Exchange (ETDEWEB)

    Costagliola, Maurizio; Riccio, Michele; Irace, Andrea; Breglio, Gianluca; Daliento, Santolo [Department of Biomedical, Electronics and Telecommunications Engineering, University of Naples ' ' Federico II' ' , via Claudio 21, 80125 Naples (Italy)

    2011-03-15

    The approximation that the current is constant in any point of the emitter is not true for solar cells operating under concentrated sunlight. The transverse paths followed by photogenerated carriers to reach metal grid electrodes causes voltage drops leading to non-uniform distributed surface potential and a consequent reduction of the conversion efficiency. Moreover, concentrating lens often provide non-uniform light intensity thus worsening non-uniform current distribution. The correct design of surface geometry of the cell (metal grid, emitter depth, sheet resistance) should always take into account the above effects. Unfortunately a lack of reliable models still exists. In this paper we analytically solve the three-dimensional semiconductor equations with proper boundary conditions and taking into account, as source term, a distributed generation contribute. The reliability of the model has been tested by numerical simulations and experimentally verified with a lock-in thermography technique (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  6. ATLAS top quark results

    CERN Document Server

    Menke, Sven; The ATLAS collaboration

    2017-01-01

    The top quark is the heaviest known fundamental particle. As it is the only quark that decays before it hadronises, analyses of events containing top quarks allow to probe the properties of bare quarks and to test perturbative QCD. This talk will focus on recent precision top-quark measurements by the ATLAS Collaboration: Single top-quark and top-quark pair production cross sections including differential distributions will be presented, as well as measurements of top-quark pair production in association with a W or Z boson and measurements of top quark properties such as the spin correlation and W boson helicity in top quark pair events.

  7. Vertically cross-linked and porous CoNi2S4 nanosheets-decorated SiC nanowires with exceptional capacitive performance as a free-standing electrode for asymmetric supercapacitors

    Science.gov (United States)

    Zhao, Jian; Li, Zhenjiang; Zhang, Meng; Meng, Alan; Li, Qingdang

    2016-11-01

    In this paper, a simple, low-cost and mild hydrothermal technology of growing vertically cross-linked ternary nickel cobalt sulfides nanosheets (CoNi2S4 NSs) with porous characteristics on SiC nanowires (SiC NWs) supporters with outstanding resistances to oxidation and corrosion, good conductivity and large specific surface area deposited directly on carbon cloth (CC) is successfully developed, forming a new family of free-standing advanced hybrid electrode for asymmetric supercapacitors (ASCs). Such integrated electrode (SiC NWs@CoNi2S4 NSs) manifests intriguing electrochemical characteristics such as high specific capacity (231.1 mA h g-1 at 2 A g-1) and rate capability due to the synergistic effect of SiC NWs and CoNi2S4 NSs with unique morphology. Additionally, an asymmetric supercapacitor is also assembled via using this special hybrid architectures as positive electrode and activated carbon (AC) on Ni foam (NF) as negative electrode, and it can yield a high energy density of 57.8 W h kg-1 with a power density of 1.6 kW kg-1 and long cycling lifespan. This study constitutes an emerging attractive strategy to reasonably design and fabricate novel SiC NWs-based nanostructured electrodes with enhanced capacity, which holds great potential to be the candidate of electrode materials for environmentally benign as well as high-performance energy storage devices.

  8. Mesoporous and Nanostructured TiO2 layer with Ultra-High Loading on Nitrogen-Doped Carbon Foams as Flexible and Free-Standing Electrodes for Lithium-Ion Batteries.

    Science.gov (United States)

    Chu, Shiyong; Zhong, Yijun; Cai, Rui; Zhang, Zhaobao; Wei, Shenying; Shao, Zongping

    2016-12-01

    A simple and green method is developed for the preparation of nanostructured TiO2 supported on nitrogen-doped carbon foams (NCFs) as a free-standing and flexible electrode for lithium-ion batteries (LIBs), in which the TiO2 with 2.5-4 times higher loading than the conventional TiO2 -based flexible electrodes acts as the active material. In addition, the NCFs act as a flexible substrate and efficient conductive networks. The nanocrystalline TiO2 with a uniform size of ≈10 nm form a mesoporous layer covering the wall of the carbon foam. When used directly as a flexible electrode in a LIB, a capacity of 188 mA h g(-1) is achieved at a current density of 200 mA g(-1) for a potential window of 1.0-3.0 V, and a specific capacity of 149 mA h g(-1) after 100 cycles at a current density of 1000 mA g(-1) is maintained. The highly conductive NCF and flexible network, the mesoporous structure and nanocrystalline size of the TiO2 phase, the firm adhesion of TiO2 over the wall of the NCFs, the small volume change in the TiO2 during the charge/discharge processes, and the high cut-off potential contribute to the excellent capacity, rate capability, and cycling stability of the TiO2 /NCFs flexible electrode.

  9. SnO2@a-Si core-shell nanowires on free-standing CNT paper as a thin and flexible Li-ion battery anode with high areal capacity

    Science.gov (United States)

    Abnavi, Amin; Sadati Faramarzi, Mojtaba; Abdollahi, Ali; Ramzani, Reza; Ghasemi, Shahnaz; Sanaee, Zeinab

    2017-06-01

    Here, we report 3D hierarchical SnO2 nanowire (NW) core-amorphous silicon shell on free-standing carbon nanotube paper (SnO2@a-Si/CNT paper) as an effective anode for flexible lithium-ion battery (LIB) application. This binder-free electrode exhibits a high initial discharge capacity of 3020 mAh g-1 with a large reversible charge capacity of 1250 mAh g-1 at a current density of 250 mA g-1. Compared to other SnO2 NW or its core-shell nanostructured anodes, the fabricated SnO2@a-Si/CNT structure demonstrates an outstanding performance with high mass loading (˜5.9 mg cm-2), high areal capacity (˜5.2 mAh cm-2), and large volumetric capacity (˜1750 mAh cm-3) after 25 cycles. Due to the incorporation of CNT paper as the current collector, the weight and thickness of the total electrode is effectively reduced with respect to the conventional LIB anodes. The fabricated electrode has a total thickness of only 30 μm and considering the total weight of the electrode (active mass + current collector), an initial discharge/charge capacity of 2460/1018 mAh g-1 is obtained. Hence, this thin, lightweight and highly flexible structure is proposed as an excellent candidate for high-performance LIB anode materials, especially in flexible electronics.

  10. Synthesis of free-standing MnO2/reduced graphene oxide membranes and electrochemical investigation of their performances as anode materials for half and full lithium-ion batteries

    Science.gov (United States)

    Zhao, Xiaojun; Wang, Gang; Wang, Hui

    2016-10-01

    MnO2 nanotubes/reduced graphene oxide (MnO2/RGO) membranes with different MnO2 contents are successfully synthesized by a facile two-step method including vacuum filtration and subsequent thermal reduction route. The MnO2 nanotubes obtained are 38 nm in diameter and homogeneously imbedded in RGO sheets as spacers. The synthesized MnO2/RGO membranes exhibit excellent mechanical flexibilities and free-standing properties. Using the membranes directly as anode materials for lithium batteries (LIBs), the membranes for half LIBs show superb cycling stabilities and rate performances. Importantly, the electrochemical performances of MnO2/RGO membranes show a strong dependence on the MnO2 nanotube contents in the hybrids. In addition, our results show that the hybrid membranes with 49.0 wt% MnO2 nanotube in half LIBs achieve a high reversible capacity of 1006.7 mAh g-1 after 100 cycles at a current density of 0.1 A g-1, which is higher lithium storage capacity than that of reported MnO2-carbon electrodes. Furthermore, the synthesized full cell (MnO2/RGO//LiCoO2) system also exhibit excellent electrochemical performances, which can be attributed to the unique microstructures of MnO2 and GRO, coupled with the strong synergistic interaction between MnO2 nanotubes and GRO sheets.

  11. Free-standing α-Co(OH)2/graphene oxide thin films fabricated through delamination and reassembling of acetate anions intercalated α-Co(OH)2 and graphene oxide in water.

    Science.gov (United States)

    Ma, KeYuan; Zhao, WenJia; Cheng, J P; Liu, Fu; Zhang, XiaoBin

    2016-04-15

    A novel hydrothermal process is demonstrated to prepare acetate anions intercalated α-Co(OH)2 that can be delaminated in water without any additional anion exchange processes. Positively charged Co(OH)2 nanosheets with lateral size of hundreds of nanometers and thickness less than 2 nm can be obtained by dispersing the as-obtained α-Co(OH)2 into water followed by sonication. The exfoliated Co(OH)2 nanosheets can be restacked into its original structure with different interlayer d-spacings. A flexible free-standing film with stacking Co(OH)2 nanosheets and graphene oxide (GO) layers can be obtained through flocculation of the Co(OH)2 nanosheets with GO nanosheets suspensions followed by a vacuum filtration, but the content of Co(OH)2 has to be kept under a low value so as to obtain films with flexible nature. Electrochemical tests show that this kind of film is not suitable to be used as electrode material for supercapacitor and lithium ion battery, because the content of active material is not high and the compacted junction between opposite charged nanosheets will prevent the electrolyte from diffusing into the interlayer space.

  12. Research Update: Enhancement of figure of merit for energy-harvesters based on free-standing epitaxial Pb(Zr0.52Ti0.480.99Nb0.01O3 thin-film cantilevers

    Directory of Open Access Journals (Sweden)

    Minh D. Nguyen

    2017-07-01

    Full Text Available All-oxide free-standing cantilevers were fabricated with epitaxial (001-oriented Pb(Zr0.52Ti0.48O3 (PZT and Pb(Zr0.52Ti0.480.99Nb0.01O3 (PNZT as piezoelectric layers and SrRuO3 electrodes. The ferroelectric and piezoelectric hysteresis loops were measured. From the zero-bias values, the figure-of-merits (FOMs for piezoelectric energy harvesting systems were calculated. For the PNZT cantilever, an extremely large value FOM = 55 GPa was obtained. This very high value is due to the large shifts of the hysteresis loops such that the zero-bias piezoelectric coefficient e31f is maximum and the zero-bias dielectric constant is strongly reduced compared to the value in the undoped PZT device. The results show that by engineering the self-bias field the energy-harvesting properties of piezoelectric systems can be increased significantly.

  13. Free-standing and mechanically flexible mats consisting of electrospun carbon nanofibers made from a natural product of alkali lignin as binder-free electrodes for high-performance supercapacitors

    Science.gov (United States)

    Lai, Chuilin; Zhou, Zhengping; Zhang, Lifeng; Wang, Xiaoxu; Zhou, Qixin; Zhao, Yong; Wang, Yechun; Wu, Xiang-Fa; Zhu, Zhengtao; Fong, Hao

    2014-02-01

    Mechanically flexible mats consisting of electrospun carbon nanofibers (ECNFs) were prepared by first electrospinning aqueous mixtures containing a natural product of alkali lignin together with polyvinyl alcohol (PVA) into composite nanofiber mats followed by stabilization in air and carbonization in an inert environment. Morphological and structural properties, as well as specific surface area, total pore volume, average pore size, and pore size distribution, of the lignin-based ECNF mats were characterized; and their electrochemical performances (i.e., capacitive behaviors) were evaluated by cyclic voltammetry, galvanostatic charge/discharge, and electrochemical impedance spectroscopy. The lignin-based ECNF mats exhibited outstanding performance as free-standing and/or binder-free electrodes of supercapacitors. For example, the ECNFs made from the composite nanofibers with mass ratio of lignin/PVA being 70/30 (i.e., ECNFs (70/30)) had the average diameter of ∼100 nm and the Brunauer-Emmett-Teller (BET) specific surface area of ∼583 m2 g-1. The gravimetric capacitance of ECNFs (70/30) electrode in 6 M KOH aqueous electrolyte exhibited 64 F g-1 at current density of 400 mA g-1 and 50 F g-1 at 2000 mA g-1. The ECNFs (70/30) electrode also exhibited excellent cycling durability/stability, and the gravimetric capacitance merely reduced by ∼10% after 6000 cycles of charge/discharge.

  14. Electroactive β-crystalline phase inclusion and photoluminescence response of a heat-controlled spin-coated PVDF/TiO2 free-standing nanocomposite film for a nanogenerator and an active nanosensor

    Science.gov (United States)

    Mehebub Alam, Md; Sultana, Ayesha; Sarkar, Debabrata; Mandal, Dipankar

    2017-09-01

    The electroactive β-phase is most desirable due to its highest piezo-, pyro- and ferroelectric properties in poly(vinylidene fluoride) (PVDF). Induction of the β-phase is successfully accomplished in titanium dioxide (TiO2) nanoparticles (NPs) doped spin-coated PVDF nanocomposite (PNC) films. The optimized yields of β-phase and homogeneous ultra-smooth free-standing PNC film is utilized in a mechanical-energy harvesting application by fabricating a nanogenerator (NG) where the typical electrical poling step is not undertaken. Under a repeated human finger touch and release process, it delivers an open-circuit voltage of 5 V. Moreover, the physical sensing capabilities of the NG are examined through harvesting mechanical energy from mouse clicking of a laptop and wrist pulse detection, which indicates that it can also be used as a nanosensor. The blue photoluminescence centred at 444 nm, which was also observed in PNC films, makes us anticipate a new type of photonic application where the design feasibility of hybrid sensors, i.e. electromechanical and photonic combination, is also possible.

  15. Reisifirmade TOP 40 aastal 2002

    Index Scriptorium Estoniae

    2003-01-01

    Reisifirmade TOP 40 aastal 2002. Reisifirmade TOP-i esikümme. Käibe TOP 40. Kasumi TOP 40. Käibe kasvu TOP 20. Kasumi kasvu TOP 20. Rentaabluse TOP 20. Omakapitali tootlikkuse TOP 20. Reisifirmade üldandmed. Reisifirmade finantsandmed. Tehnilise käibe alusel arvutatud edetabelid: Reisifirmade TOP 25; Käibe TOP 40; Rentaabluse TOP 10; Käibe kasvu TOP 10

  16. Reisifirmade TOP 40 aastal 2002

    Index Scriptorium Estoniae

    2003-01-01

    Reisifirmade TOP 40 aastal 2002. Reisifirmade TOP-i esikümme. Käibe TOP 40. Kasumi TOP 40. Käibe kasvu TOP 20. Kasumi kasvu TOP 20. Rentaabluse TOP 20. Omakapitali tootlikkuse TOP 20. Reisifirmade üldandmed. Reisifirmade finantsandmed. Tehnilise käibe alusel arvutatud edetabelid: Reisifirmade TOP 25; Käibe TOP 40; Rentaabluse TOP 10; Käibe kasvu TOP 10

  17. Intergenerational Top Income Persistence

    DEFF Research Database (Denmark)

    Munk, Martin D.; Bonke, Jens; Hussain, M. Azhar

    2016-01-01

    In this paper, we investigate intergenerational top earnings and top income mobility in Denmark. Access to administrative registers allowed us to look at very small fractions of the population. We find that intergenerational mobility is lower in the top when including capital income in the income...... measure— for the rich top 0.1% fathers and sons the elasticity is 0.466. Compared with Sweden, however, the intergenerational top income persistence is about half the size in Denmark....

  18. Top quark property measurements in single top

    CERN Document Server

    AUTHOR|(INSPIRE)INSPIRE-00386283; The ATLAS collaboration

    2016-01-01

    A review of the recent results on measurements of top quark properties in single top quark processes, performed at the LHC by ATLAS and CMS is presented. The measurements are in good agreement with predictions and no deviations from Standard Model expectations have been observed.

  19. ATLAS Top Quark Results

    CERN Document Server

    Black, Kevin; The ATLAS collaboration

    2017-01-01

    The top quark is the heaviest known fundamental particle. As it is the only quark that decays before it hadronizes, this gives us the unique opportunity to probe the properties of bare quarks at the Large Hadron Collider. This talk will present highlights of a few recent precision measurements by the ATLAS Collaboration of the top quark using 13 TeV and 8 TeV collision data: top-quark pair and single top production cross sections including differential distributions will be presented alongside top quark properties measurements. These measurements, including results using boosted top quarks, probe our understanding of top quark production in the TeV regime. Measurements of the top quark mass and searches for rare top quark decays are also presented.

  20. Top quark properties

    Indian Academy of Sciences (India)

    Yuji Takeuchi

    2012-10-01

    Since the top quark was discovered at Tevatron in 1995, many top quark properties have been measured. However, the top quark is still interesting due to unique features which originate from the extremely heavy mass, and providing various test grounds on the Standard Model as well as searches for a new physics. Though the measurements of the top quark had been performed only at Tevatron so far, LHC is now ready for measurements with more top quarks than Tevatron. In this article, recent measurements of top quark properties from Tevatron (CDF and DØ) as well as LHC (ATLAS and CMS) are presented.

  1. Audiitorfirmade TOP 50 aastal 2000

    Index Scriptorium Estoniae

    2001-01-01

    Audiitorfirmade käibe TOP 50, käibe kasvu TOP 25, käibe languse TOP 15, kasumi TOP 50, kasumi kasvu TOP 10, kasumi languse TOP 10, audiitorfirmade finantsnäitajad. Rentaabluse TOP 50, varade tootlikkuse TOP 50

  2. Audiitorfirmade TOP 50 aastal 2000

    Index Scriptorium Estoniae

    2001-01-01

    Audiitorfirmade käibe TOP 50, käibe kasvu TOP 25, käibe languse TOP 15, kasumi TOP 50, kasumi kasvu TOP 10, kasumi languse TOP 10, audiitorfirmade finantsnäitajad. Rentaabluse TOP 50, varade tootlikkuse TOP 50

  3. Top quark physics

    Energy Technology Data Exchange (ETDEWEB)

    Ahmadov, A.; Azuelos, G.; Bauer, U.; Belyaev, A.; Berger, E. L.; Sullivan, Z.; Tait, T. M. P.

    2000-03-24

    The top quark, when it was finally discovered at Fermilab in 1995 completed the three-generation structure of the Standard Model (SM) and opened up the new field of top quark physics. Viewed as just another SM quark, the top quark appears to be a rather uninteresting species. Produced predominantly, in hadron-hadron collisions, through strong interactions, it decays rapidly without forming hadrons, and almost exclusively through the single mode t {r_arrow} Wb. The relevant CKM coupling V{sub tb} is already determined by the (three-generation) unitarity of the CKM matrix. Rare decays and CP violation are unmeasurable small in the SM. Yet the top quark is distinguished by its large mass, about 35 times larger than the mass of the next heavy quark, and intriguingly close to the scale of electroweak (EW) symmetry breaking. This unique property raises a number of interesting questions. Is the top quark mass generated by the Higgs mechanism as the SM predicts and is its mass related to the top-Higgs-Yukawa coupling? Or does it play an even more fundamental role in the EW symmetry breaking mechanism? If there are new particles lighter than the top quark, does the top quark decay into them? Could non-SM physics first manifest itself in non-standard couplings of the top quark which show up as anomalies in top quark production and decays? Top quark physics tries to answer these questions. Several properties of the top quark have already been examined at the Tevatron. These include studies of the kinematical properties of top production, the measurements of the top mass, of the top production cross-section, the reconstruction of t{bar t}pairs in the fully hadronic final states, the study of {tau} decays of the top quark, the reconstruction of hadronic decays of the W boson from top decays, the search for flavor changing neutral current decays, the measurement of the W helicity in top decays, and bounds on t{bar t} spin correlations. Most of these measurements are limited by

  4. Top Production at LHCb

    CERN Multimedia

    Santana Rangel, Murilo

    2015-01-01

    Single and pair top production in the forward direction at the LHC allows for precision tests of the Standard Model. The observation of top quarks in 7 and 8 TeV data and prospects for precision measurements are shown.

  5. Top-ology

    OpenAIRE

    Quigg, Chris

    1995-01-01

    I compare the anticipated properties of the top quark with what is known experimentally about the heaviest fermion. I review the scientific opportunities that will be presented in the near future by copious samples of top. These include refined tests of electroweak radiative corrections, studies of the nature of top itself, and exploration of electroweak symmetry breaking. I conclude by illustrating top's influence in the everyday world.

  6. Top physics at ATLAS

    CERN Document Server

    Romano, M

    2016-01-01

    This paper is an overview of recent results on top-quark physics obtained by the ATLAS Collaboration from the analysis of pp collisions at $\\sqrt s$= 7 and 8TeV at the Large Hadron Collider. Total and differential top-quark pair (t$\\overline t$), single top and t$\\overline t$+$\\gamma$ cross-sections and top properties measurements are presented.

  7. Top quark measurements

    CERN Document Server

    Iorio, Alberto Orso Maria

    2016-01-01

    Measurements of top quarks from Run-I and Run-II of the LHC are presented. Results on dif- ferential and inclusive top quark production cross sections, measured by the ATLAS, CMS and LHCb experiments, and measurements of top quark properties and mass are reported.

  8. Spherical Tippe Tops

    Science.gov (United States)

    Cross, Rod

    2013-01-01

    A tippe top (see Fig. 1) is usually constructed as a truncated sphere with a cylindrical peg on top, as indicated in Fig. 2(a). When spun rapidly on a horizontal surface, a tippe top spins about a vertical axis while rotating slowly about a horizontal axis until the peg touches the surface. At that point, weight is transferred to the peg, the…

  9. Top Quark Results

    CERN Document Server

    ATLAS collaboration; LHCb collaboration

    2016-01-01

    Measurements of top quarks from Run-I and Run-II of the LHC are presented. Results on differential and inclusive top quark production cross sections, measured by the ATLAS, CMS and LHCb experiments, and measurements of top quark properties and mass are reported.

  10. Plating in Top Agar

    OpenAIRE

    sprotocols

    2014-01-01

    1. Warm plates to room temperature before use. Cold plates causes the top agar to solidify irregularly. DO not warm plates to 37° as the top agar will take forever to solidify. - Prepare top agar as the appropriate liquid medium with 0.7% agar. Keeping 100 mL bottles is convenient. For phages, use λ top agar, which is less rich and yields bigger plaques. - Melt top agar in the microwave completely. Allow the agar to boil after liquification; incompletely melted agar looks liquid, but is...

  11. CDF Top Physics

    Science.gov (United States)

    Tartarelli, G. F.; CDF Collaboration

    1996-05-01

    The authors present the latest results about top physics obtained by the CDF experiment at the Fermilab Tevatron collider. The data sample used for these analysis (about 110 pb{sup{minus}1}) represents almost the entire statistics collected by CDF during four years (1992--95) of data taking. This large data size has allowed detailed studies of top production and decay properties. The results discussed here include the determination of the top quark mass, the measurement of the production cross section, the study of the kinematics of the top events and a look at top decays.

  12. Top quark properties

    CERN Document Server

    Cuevas Maestro, Javier

    2016-01-01

    An overview of recent top quark measurements in proton-proton collisions at 7, and 8 TeV in data collected with the CMS and ATLAS experiments at the LHC, using a data sample collected during the years 2011, 2012 is presented. The results include measurements of top-quark pairs spin correlation, the top pair charge asymmetry, the cross section of top-quark pair events produced in association with a W or a Z boson. The mass of the top quark is estimated by different methods. Some results on the same topics are also presented in data collected by the CDF and D0 collaborations at the Tevatron collider.

  13. Top quark physics

    Energy Technology Data Exchange (ETDEWEB)

    Erbacher, Robin D.; /UC, Davis

    2005-10-01

    While the top quark was discovered in 1995 at the Fermilab Tevatron, a decade later they still have very little information about the top. As the heaviest particle yet discovered, the top quark is interesting in and of itself, but some speculate that it may play a special role in physics beyond the Standard Model. With Run 2 of the Tevatron well underway, they have the opportunity to study top quark properties with much better sensitivity, and to test whether top quarks behave as predicted by current theories. This article focuses on the basics of top quark physics at the Tevatron, highlighting only a sample of the many recent measurements, as new results are being released monthly, and constantly changing the landscape of our knowledge of top.

  14. Turismifirmade 2000. a. TOP 30

    Index Scriptorium Estoniae

    2001-01-01

    Turismiettevõtete üldandmed: turismiettevõtete finantsnäitajad; käibe TOP 30; käibe kasvu TOP 10; kasumi TOP 20; kasumi kasvu TOP 10; kasumi languse TOP; rentaabluse TOP 10; varade tootlikkuse TOP 10

  15. Ekspedeerimisfirmade TOP 45 aastal 2003

    Index Scriptorium Estoniae

    2004-01-01

    Ilmunud ka: Delovõje Vedomosti : Transport i logistika, 24. nov. 2004, lk. 14. Käibe TOP 15. Kasumi TOP 15. Rentaabluse TOP 15. Käibe kasvu TOP 15. Kasumi kasvu TOP 15. Omakapitali tootlikkuse TOP 15. Ekspediitorite üldandmed. Ekspediitorfirmade finantsandmed. Lisa: TOP-i koostamise metoodika

  16. Autotranspordiettevõtete TOP 90

    Index Scriptorium Estoniae

    2005-01-01

    Ilmunud ka: Delovõje Vedomosti : Transport i Logistika 30. nov. lk. 10. Autotranspordiettevõtete TOP 90; Käibe TOP 15; Käibe kasvu TOP 15; Kasumi TOP 15; Kasumi kasvu TOP15; Rentaabluse TOP 15; Omakapitali tootlikkuse TOP 15; Autotranspordiettevõtete üld- ja finantsandmed

  17. Turismifirmade 2000. a. TOP 30

    Index Scriptorium Estoniae

    2001-01-01

    Turismiettevõtete üldandmed: turismiettevõtete finantsnäitajad; käibe TOP 30; käibe kasvu TOP 10; kasumi TOP 20; kasumi kasvu TOP 10; kasumi languse TOP; rentaabluse TOP 10; varade tootlikkuse TOP 10

  18. Ehitusmaterjalitootjate TOP 70 aastal 2003

    Index Scriptorium Estoniae

    2004-01-01

    Ilmunud ka: Delovõje Vedomosti : Stroitelstvo, 29. sept. 2004, lk. 2,4. Ehitusmaterjalitootjate TOP 70; Käibe TOP 10; Käibe kasvu TOP 10; Kasumi TOP 10; Kasumi kasvu TOP 10; Rentaabluse TOP 10; Omakapitali tootlikkuse TOP. Ehitusmaterjalitootjate üldandmed

  19. Ekspedeerimisfirmade TOP 45 aastal 2003

    Index Scriptorium Estoniae

    2004-01-01

    Ilmunud ka: Delovõje Vedomosti : Transport i logistika, 24. nov. 2004, lk. 14. Käibe TOP 15. Kasumi TOP 15. Rentaabluse TOP 15. Käibe kasvu TOP 15. Kasumi kasvu TOP 15. Omakapitali tootlikkuse TOP 15. Ekspediitorite üldandmed. Ekspediitorfirmade finantsandmed. Lisa: TOP-i koostamise metoodika

  20. Analysis of Flat-Plate Solar Array and Solar Lantern

    Directory of Open Access Journals (Sweden)

    P. L. N. V. Aashrith

    2014-05-01

    Full Text Available A very detailed theortical analysis of a solar array has been carried out based on established values of solar radiation data to predict the performance of solar lamp . The analysis is based on established theory about flat-plate collectors. Top heat loss coefficient (Ut, Bottom heat loss coefficient (Ub, Overall heat loss coefficient (Ul, Useful energy (Qu, efficiency (hp of the flat-plate solar array and efficiency (hl of the solar lantern has been calculated.

  1. The stop on top

    CERN Document Server

    Zakareishvili, Tamar

    2016-01-01

    Supersymmetric partners of the top quark have been sought since the top quark has been discovered at the Tevatron. The searches are more easily performed in scenarios where the mass splitting between the top and the stop is large and where differences in kinematics are striking. The region in which top and stop are almost degenerate in mass is more difficult to explore experimentally as the final state kinematics are very similar, apart from angular-related distributions which reflect the spin/parity difference between the two particles. Usually the searches are performed looking for deviations on the measured top-quark pair production cross section with respect to the standard model prediction, or looking to simple variables such as the difference in the azimuthal angle between two leptons produced after top quark decays.

  2. Study of the Mg incorporation in CdTe for developing wide band gap Cd{sub 1-x}Mg{sub x}Te thin films for possible use as top-cell absorber in a tandem solar cell

    Energy Technology Data Exchange (ETDEWEB)

    Martinez, Omar S. [Centro de Investigacion en Energia, Universidad Nacional Autonoma de Mexico, 62580 Temixco, Morelos (Mexico); Universidad Politecnica del Estado de Guerrero, Comunidad de Puente Campuzano, C.P. 40325 Taxco de Alarcon, Guerrero (Mexico); Millan, Aduljay Remolina [Centro de Investigacion en Energia, Universidad Nacional Autonoma de Mexico, 62580 Temixco, Morelos (Mexico); Huerta, L.; Santana, G. [Instituto de Investigaciones en Materiales, Universidad Nacional Autonoma de Mexico. C.P 04510 Mexico D.F. (Mexico); Mathews, N.R.; Ramon-Garcia, M.L.; Morales, Erik R. [Centro de Investigacion en Energia, Universidad Nacional Autonoma de Mexico, 62580 Temixco, Morelos (Mexico); Mathew, X., E-mail: xm@cie.unam.mx [Centro de Investigacion en Energia, Universidad Nacional Autonoma de Mexico, 62580 Temixco, Morelos (Mexico)

    2012-02-15

    Highlights: Black-Right-Pointing-Pointer Thin films of Cd{sub 1-x}Mg{sub x}Te with high spatial uniformity and band gap in the range of 1.6-1.96 eV were deposited by vacuum co-evaporation of CdTe and Mg. Black-Right-Pointing-Pointer Obtained Cd{sub 1-x}Mg{sub x}Te films have the structural characteristics of the CdTe, evidence of the change in atomic scattering due to incorporation of Mg was observed. Black-Right-Pointing-Pointer XRD and XPS data confirmed the incorporation of Mg in the lattice of CdTe. Black-Right-Pointing-Pointer SEM images revealed the impact of Mg incorporation on the morphology of the films, the changes in grain size and grain morphology are noticeable. - Abstract: Thin films of Cd{sub 1-x}Mg{sub x}Te with band gap in the range of 1.6-1.96 eV were deposited by vacuum co-evaporation of CdTe and Mg on glass substrates heated at 300 Degree-Sign C. Different experimental techniques such as XRD, UV-vis spectroscopy, SEM, and XPS were used to study the effect of Mg incorporation into the lattice of CdTe. The band gap of the films showed a clear tendency to increase as the Mg content in the film is increased. The Cd{sub 1-x}Mg{sub x}Te films maintain all the structural characteristics of the CdTe, however, diminishing of intensity for the XRD patterns is observed due to both change in preferential orientation and change in atomic scattering due to the incorporation of Mg. SEM images showed significant evidences of morphological changes due to the presence of Mg. XRD, UV-vis spectroscopy, and XPS data confirmed the incorporation of Mg in the lattice of CdTe. The significant increase in band gap of CdTe due to incorporation of Mg suggests that the Cd{sub 1-x}Mg{sub x}Te thin film is a candidate material to use as absorber layer in the top-cell of a tandem solar cell.

  3. The Top Triangle Moose

    Science.gov (United States)

    Chivukula, R. S.; Christensen, N. D.; Coleppa, B.; Simmons, E. H.

    2011-01-01

    We introduce a deconstructed model that incorporates both Higgsless and top-color mechanisms. The model alleviates the typical tension in Higgsless models between obtaining the correct top quark mass and keeping Δρ small. It does so by singling out the top quark mass generation as arising from a Yukawa coupling to an effective top-Higgs which develops a small vacuum expectation value, while electroweak symmetry breaking results largely from a Higgsless mechanism. As a result, the heavy partners of the SM fermions can be light enough to be seen at the LHC.

  4. The Top Triangle Moose

    CERN Document Server

    Chivukula, R S; Coleppa, B; Simmons, E H

    2010-01-01

    We introduce a deconstructed model that incorporates both Higgsless and top-color mechanisms. The model alleviates the typical tension in Higgsless models between obtaining the correct top quark mass and keeping delta-rho small. It does so by singling out the top quark mass generation as arising from a Yukawa coupling to an effective top-Higgs which develops a small vacuum expectation value, while electroweak symmetry breaking results largely from a Higgsless mechanism. As a result, the heavy partners of the SM fermions can be light enough to be seen at the LHC.

  5. Top Quark Measurements

    CERN Document Server

    Juste, A

    2006-01-01

    Ten years after its discovery at the Tevatron collider, we still know little about the top quark. Its large mass suggests it may play a key role in the mechanism of Electroweak Symmetry Breaking (EWSB), or open a window of sensitivity to new physics related to EWSB and preferentially coupled to it. To determine whether this is the case, precision measurements of top quark properties are necessary. The high statistics samples being collected by the Tevatron experiments during Run II start to incisively probe the top quark sector. This report summarizes the experimental status of the top quark, focusing in particular on the recent measurements from the Tevatron Run II.

  6. Top Physics at CDF

    Energy Technology Data Exchange (ETDEWEB)

    Moon, Chang-Seong

    2011-06-01

    We present the recent results of top-quark physics using up to 6 fb{sup -1} of p{bar p} collisions at a center of mass energy of {radical}s = 1.96 TeV analyzed by the CDF collaboration. Thanks to this large data sample, precision top quark measurements are now a reality at the Tevatron. Further, several new physics signals could appear in this large dataset. We will present the latest measurements of top quark intrinsic properties as well as direct searches for new physics in the top sector.

  7. Top Physics (CMS)

    CERN Document Server

    Daskalakis, Georgios

    2016-01-01

    Recent results on the inclusive and differential production cross sections of top-quark pair and single top-quark processes are presented, obtained using data from proton-proton collisions collected with the CMS detector at the LHC. The large centre-of-mass energies available at LHC allow for the copious production of top-quark pairs in association with other final state particles at high transverse momentum. Measurements of such processes as well as of the top-quark mass and other properties will be discussed. The results are compared with the most up-to-date standard model theory predictions.

  8. Top at Twenty

    CERN Document Server

    2015-01-01

    The "Top at Twenty" workshop is dedicated to the celebration of 20 years since the top quark discovery at Fermilab in 1995. Speakers from all experiments capable of studying top quark, ATLAS, CDF, CMS and DZero, will present the most recent results of the top quark studies based on Run II of the Tevatron and Run I of the LHC. Reviews of such fundamental measurements as mass of the top quark, its spin, charge and production properties are planned with some of them orders of magnitude better in precision in comparison with original CDF and DZero papers announcing the top quark discovery. Measurements of top quark production and decay that illuminate the nature of the Higgs boson and seek new phenomena will be presented. Theoretical talks on how the top quark fits into the Standard Model and its potential extensions will also be presented. This workshop will complement the yearly Top Workshop which is held in September and will benefit from many new results expected to be presented at winter conferences in 2015...

  9. Ekspedeerimisettevõtete TOP 50

    Index Scriptorium Estoniae

    2006-01-01

    Ilmunud ka: Delovõje Vedomosti : Transport i Logistika nr. 11, 29. nov. lk. 32-35. Ekspedeerimisettevõtete TOP. Vt. samas: Käibe TOP 10; Käibekasvu TOP 10; Kasumi TOP 10; Kasumikasvu TOP 10; Rentaabluse TOP 10; ROE TOP 10; Ekspedeerimisettevõtete üld- ja finantsandmed. Ajal. Delovõje Vedomosti : Transport i Logistika toodud ainult Ekspedeerimisettevõtete TOP 50

  10. Ekspedeerimisettevõtete TOP 50

    Index Scriptorium Estoniae

    2006-01-01

    Ilmunud ka: Delovõje Vedomosti : Transport i Logistika nr. 11, 29. nov. lk. 32-35. Ekspedeerimisettevõtete TOP. Vt. samas: Käibe TOP 10; Käibekasvu TOP 10; Kasumi TOP 10; Kasumikasvu TOP 10; Rentaabluse TOP 10; ROE TOP 10; Ekspedeerimisettevõtete üld- ja finantsandmed. Ajal. Delovõje Vedomosti : Transport i Logistika toodud ainult Ekspedeerimisettevõtete TOP 50

  11. Top quark theory

    NARCIS (Netherlands)

    E. Laenen

    2011-01-01

    The theoretical aspects of a number of top quark properties such as its mass and its couplings are reviewed. Essential aspects in the theoretical description of top quark production, singly, in pairs and in association, as well as its decay related to spin and angular correlations are discussed.

  12. Top quark theory

    Indian Academy of Sciences (India)

    Eric Laenen

    2012-10-01

    The theoretical aspects of a number of top quark properties such as its mass and its couplings are reviewed. Essential aspects in the theoretical description of top quark production, singly, in pairs and in association, as well as its decay related to spin and angular correlations are discussed.

  13. The Driven Spinning Top

    Science.gov (United States)

    Grosu, Ioan; Featonby, David

    2016-01-01

    This driven top is quite a novelty and can, with some trials, be made using the principles outlined here. This new top has many applications in developing both understanding and skills and these are detailed in the article. Depending on reader's available time and motivation they may feel an urge to make one themselves, or simply invest a few…

  14. The Driven Spinning Top

    Science.gov (United States)

    Grosu, Ioan; Featonby, David

    2016-01-01

    This driven top is quite a novelty and can, with some trials, be made using the principles outlined here. This new top has many applications in developing both understanding and skills and these are detailed in the article. Depending on reader's available time and motivation they may feel an urge to make one themselves, or simply invest a few…

  15. Top Quark Mass

    CERN Document Server

    Mulders, Martijn

    2016-01-01

    Ever since the discovery of the top quark at the Tevatron collider in 1995 the measurement of its mass has been a high priority. As one of the fundamental parameters of the Standard Theory of particle physics, the precise value of the top quark mass together with other inputs provides a test for the self-consistency of the theory, and has consequences for the stability of the Higgs field that permeates the Universe. In this review I will briefly summarize the experimental techniques used at the Tevatron and the LHC experiments throughout the years to measure the top quark mass with ever improving accuracy, and highlight the recent progress in combining all measurements in a single world average combination. As experimental measurements became more precise, the question of their theoretical interpretation has become important. The difficulty of relating the measured quantity to the fundamental top mass parameter has inspired alternative measurement methods that extract the top mass in complementary ways. I wil...

  16. Landfill Top Covers

    DEFF Research Database (Denmark)

    Scheutz, Charlotte; Kjeldsen, Peter

    2011-01-01

    is landscaped in order to fit into the surrounding area/environment or meet specific plans for the final use of the landfill. To fulfill the above listed requirements landfill covers are often multicomponent systems which are placed directly on top of the waste. The top cover may be placed immediately after...... the landfill section has been filled or several years later depending on the settlement patterns. Significant differential settlements may disturb the functioning of the top cover. The specific design of the cover system depends on the type of waste landfilled (municipal, hazardous, or inert waste...... however, top covers may be the only environmental protection measure. In some landfill regulations (for instance the Subtitle D landfills receiving municipal solid waste in the USA) it is required to minimize infiltration into the waste layers. Therefore top covers containing liner components...

  17. Top physics at CDF

    Energy Technology Data Exchange (ETDEWEB)

    Hughes, R.E. [Univ. of Rochester, NY (United States)

    1997-01-01

    We report on top physics results using a 100 pb{sup -1} data sample of p{bar p} collisions at {radical}s = 1.8 TeV collected with the Collider Detector at Fermilab (CDF). We have identified top signals in a variety of decay channels, and used these channels to extract a measurement of the top mass and production cross section. A subset of the data (67 pb{sup -1}) is used to determine M{sub top} = 176 {+-} 8(stat) {+-} 10(syst) and {sigma}(tt) = 7.6 {sub -2.0}{sup +2.4} pb. We present studies of the kinematics of t{bar t} events and extract the first direct measurement of V{sub tb}. Finally, we indicate prospects for future study of top physics at the Tevatron.

  18. Top quark mass measurement

    Energy Technology Data Exchange (ETDEWEB)

    Maki, Tuula [Univ. of Helsinki (Finland)

    2008-03-18

    The top quark is the heaviest elementary particle. Its mass is one of the fundamental parameters of the standard model of particle physics, and an important input to precision electroweak tests. This thesis describes three measurements of the top-quark mass in the dilepton decay channel. The dilepton events have two neutrinos in the final state; neutrinos are weakly interacting particles that cannot be detected with a multipurpose experiment. Therefore, the signal of dilepton events consists of a large amount of missing energy and momentum carried off by the neutrinos. The top-quark mass is reconstructed for each event by assuming an additional constraint from a top mass independent distribution. Template distributions are constructed from simulated samples of signal and background events, and parametrized to form continuous probability density functions. The final top-quark mass is derived using a likelihood fit to compare the reconstructed top mass distribution from data to the parametrized templates. One of the analyses uses a novel technique to add top mass information from the observed number of events by including a cross-section-constraint in the likelihood function. All measurements use data samples collected by the CDF II detector.

  19. Audiitorite TOP 50 aastal 2005

    Index Scriptorium Estoniae

    2006-01-01

    Audiitorite TOP. Vt. samas: Käibe TOP 10; Käibe kasvu TOP 10; Kasumi TOP 10; Kasumi kasvu TOP 10; Rentaabluse TOP 10; ROE TOP 10; Ketlin Priilinn. Kasvu tagavad lojaalsed kliendid; Klient on audiitori parim müügimees; Teeli Remmelg. Kliendid vaatavad pigem kvaliteeti kui madalat hinda. Kommenteerivad Signe Keernik ja Kalle Lahe. Tabel: Audiitoriettevõtete üld- ja finantsandmed

  20. Audiitorite TOP 50 aastal 2005

    Index Scriptorium Estoniae

    2006-01-01

    Audiitorite TOP. Vt. samas: Käibe TOP 10; Käibe kasvu TOP 10; Kasumi TOP 10; Kasumi kasvu TOP 10; Rentaabluse TOP 10; ROE TOP 10; Ketlin Priilinn. Kasvu tagavad lojaalsed kliendid; Klient on audiitori parim müügimees; Teeli Remmelg. Kliendid vaatavad pigem kvaliteeti kui madalat hinda. Kommenteerivad Signe Keernik ja Kalle Lahe. Tabel: Audiitoriettevõtete üld- ja finantsandmed

  1. Viljandimaa ettevõtete TOP 50

    Index Scriptorium Estoniae

    2005-01-01

    Viljandimaa ettevõtete TOP 50; Käibe TOP 35; Kasumi TOP 35; Käibe kasvu TOP 20; Kasumi kasvu TOP 20; Rentaabluse TOP 20; Omakapitali tootlikkuse TOP 20; Viljandimaa ettevõtete üld- ja finantsandmed

  2. Jõgevamaa ettevõtete TOP 50

    Index Scriptorium Estoniae

    2005-01-01

    Jõgevamaa ettevõtete TOP 50; Käibe TOP 35; Kasumi TOP 35; Käibe kasvu TOP 20; Kasumi kasvu TOP 20; Rentaabluse TOP 20; Omakapitali tootlikkuse TOP 20; Jõgevamaa ettevõtete üld- ja finantsandmed

  3. Põlvamaa ettevõtete TOP 50

    Index Scriptorium Estoniae

    2004-01-01

    Ettevõtete TOP 50. Käibe TOP 40. Kasumi TOP 40. Käibe kasvu TOP 20. Kasumi kasvu TOP 20. Rentaabluse TOP 20. Omakapitali tootlikkuse TOP 20. Põlvamaa firmade üldandmed. Põlvamaa firmade finantsandmed

  4. Jõgevamaa ettevõtete TOP 55

    Index Scriptorium Estoniae

    2004-01-01

    Jõgevamaa ettevõtete TOP 55 aastal 2003. Käibe TOP 40. Kasumi TOP 40. Käibe kasvu TOP 20. Kasumi kasvu TOP 20. Rentaabluse TOP 20. Omakapitali tootlikkuse TOP 20. Jõgevamaa firmade üld- ja finantsandmed

  5. Jõgevamaa ettevõtete TOP 55

    Index Scriptorium Estoniae

    2004-01-01

    Jõgevamaa ettevõtete TOP 55 aastal 2003. Käibe TOP 40. Kasumi TOP 40. Käibe kasvu TOP 20. Kasumi kasvu TOP 20. Rentaabluse TOP 20. Omakapitali tootlikkuse TOP 20. Jõgevamaa firmade üld- ja finantsandmed

  6. Põlvamaa ettevõtete TOP 50

    Index Scriptorium Estoniae

    2004-01-01

    Ettevõtete TOP 50. Käibe TOP 40. Kasumi TOP 40. Käibe kasvu TOP 20. Kasumi kasvu TOP 20. Rentaabluse TOP 20. Omakapitali tootlikkuse TOP 20. Põlvamaa firmade üldandmed. Põlvamaa firmade finantsandmed

  7. Jõgevamaa ettevõtete TOP 50

    Index Scriptorium Estoniae

    2005-01-01

    Jõgevamaa ettevõtete TOP 50; Käibe TOP 35; Kasumi TOP 35; Käibe kasvu TOP 20; Kasumi kasvu TOP 20; Rentaabluse TOP 20; Omakapitali tootlikkuse TOP 20; Jõgevamaa ettevõtete üld- ja finantsandmed

  8. Viljandimaa ettevõtete TOP 50

    Index Scriptorium Estoniae

    2005-01-01

    Viljandimaa ettevõtete TOP 50; Käibe TOP 35; Kasumi TOP 35; Käibe kasvu TOP 20; Kasumi kasvu TOP 20; Rentaabluse TOP 20; Omakapitali tootlikkuse TOP 20; Viljandimaa ettevõtete üld- ja finantsandmed

  9. Top Physics in WHIZARD

    CERN Document Server

    Reuter, J; Chokoufe, B; Hoang, A; Kilian, W; Stahlhofen, M; Teubner, T; Weiss, C

    2016-01-01

    In this talk we summarize the top physics setup in the event generator WHIZARD with a main focus on lepton colliders. This includes full six-, eight- and ten-fermion processes, factorized processes and spin correlations. For lepton colliders, QCD NLO processes for top quark physics are available and will be discussed. A special focus is on the top-quark pair threshold, where a special implementation combines a non-relativistic effective-field theory calculation augmented by a next-to-leading threshold logarithm resummation with a continuum relativistic fixed-order QCD NLO simulation.

  10. Top physics in WHIZARD

    Energy Technology Data Exchange (ETDEWEB)

    Reuter, Juergen; Chokoufe Nejad, Bijan [DESY, Hamburg (Germany). Theory Group; Bach, Fabian [European Commission, Eurostat, Luxembourg (Luxembourg); Hoang, Andre [Vienna Univ. (Austria). Faculty of Physics; Vienna Univ. (Austria). Erwin Schroedinger International Inst. for Mathematical Physics; Kilian, Wolfgang [Siegen Univ. (Germany); Stahlhofen, Maximilian [Mainz Univ. (Germany). PRISMA Cluster of Excellence; Teubner, Thomas [Liverpool Univ. (United Kingdom). Dept. of Mathematical Sciences; Weiss, Christian [DESY, Hamburg (Germany). Theory Group; Siegen Univ. (Germany)

    2016-03-15

    In this talk we summarize the top physics setup in the event generator WHIZARD with a main focus on lepton colliders. This includes full six-, eight- and ten-fermion processes, factorized processes and spin correlations. For lepton colliders, QCD NLO processes for top quark physics are available and discussed. A special focus is on the top-quark pair threshold, where a special implementation combines a non-relativistic effective field theory calculation augmented by a next-to-leading threshold logarithm resummation with a continuum relativistic fixed-order QCD NLO simulation.

  11. Cleaner for Solar-Collector Covers

    Science.gov (United States)

    Frickland, P. O.; Cleland, E. L.

    1983-01-01

    Simple self-contained cleaning system proposed for solar collectors or solar-collector protective domes. Perforated transparent plastic cap attached to top of protective dome in heliostat solar-energy collection system distributes cleaning fluid over surface of dome without blocking significant fraction of solar radiation.

  12. Landfill Top Covers

    DEFF Research Database (Denmark)

    Scheutz, Charlotte; Kjeldsen, Peter

    2011-01-01

    the landfill section has been filled or several years later depending on the settlement patterns. Significant differential settlements may disturb the functioning of the top cover. The specific design of the cover system depends on the type of waste landfilled (municipal, hazardous, or inert waste...... such as lowpermeability clay soils and geomembranes are required. The avoidance of water input to organic waste may impede the microbial stabilization processes including gas generation. Therefore watertight top covers may be in conflict with the purposes of reactor landfills (see Chapter 10.6). At some sites covers...... sometimes are made to include components for recirculation of landfill leachate (see Section 10.9.2 for more details). The top cover is an important factor in the water management of landfills. Details about water infiltration through top covers and its influence on the hydrology of the landfill is covered...

  13. Top quark physics: Overview

    Energy Technology Data Exchange (ETDEWEB)

    Parke, S.

    1998-01-01

    In this presentation I will primarily focus on top quark physics but I will include a discussion of the W-boson mass and the possibility of discovering a light Higgs boson via associated production at the Tevatron.

  14. Telekommunikatsiooni & arvutitootjate TOP

    Index Scriptorium Estoniae

    2006-01-01

    Telekommunikatsiooni TOP 30. Tabelid. Vt. samas: Indrek Kald. Elisa ka tänavu esikohal; Väike Tele2 võidab paindlikkusest; Kernel läks üle piiri. Diagrammid. Arvutifirmade TOP 100. Tabelid. Vt. samas: Enn Heinsoo. Esikoha tõi kontori müük; Proeksperdil suund välisturgudele;¡ Ida-Eesti turg arenevale firmale kitsas. Diagrammid. Nimekiri: Omanikud

  15. Telekommunikatsiooni & arvutitootjate TOP

    Index Scriptorium Estoniae

    2006-01-01

    Telekommunikatsiooni TOP 30. Tabelid. Vt. samas: Indrek Kald. Elisa ka tänavu esikohal; Väike Tele2 võidab paindlikkusest; Kernel läks üle piiri. Diagrammid. Arvutifirmade TOP 100. Tabelid. Vt. samas: Enn Heinsoo. Esikoha tõi kontori müük; Proeksperdil suund välisturgudele;¡ Ida-Eesti turg arenevale firmale kitsas. Diagrammid. Nimekiri: Omanikud

  16. Naisjuhtidega ettevõtete TOP

    Index Scriptorium Estoniae

    2005-01-01

    Naisjuhtidega ettevõtete TOP; Naisjuhtidega ettevõtete üld- ja finantsandmed; Riigi- ja kohaliku omavalitsuse asutuste naisjuhtide TOP; Riigi- ja kohaliku omavalitsuse asutuste eelarve TOP; Riigi- ja kohaliku omavalitsuse asutuste töötajate arvu TOP; Riigi- ja kohaliku omavalitsuse asutuste naisjuhtide palga TOP 28

  17. Top Quark Mass

    Science.gov (United States)

    Mulders, Martijn

    2016-10-01

    Ever since the discovery of the top quark at the Tevatron collider in 1995 the measurement of its mass has been a high priority. As one of the fundamental parameters of the Standard Theory of particle physics, the precise value of the top quark mass together with other inputs provides a test for the self-consistency of the theory, and has consequences for the stability of the Higgs field that permeates the Universe. In this review I will briefly summarize the experimental techniques used at the Tevatron and the LHC experiments throughout the years to measure the top quark mass with ever improving accuracy, and highlight the recent progress in combining all measurements in a single world average combination. As experimental measurements became more precise, the question of their theoretical interpretation has become important. The difficulty of relating the measured quantity to the fundamental top mass parameter has inspired alternative measurement methods that extract the top mass in complementary ways. I will discuss the status of those techniques and their results, and present a brief outlook of further improvements in the experimental determination of the top quark mass to be expected at the LHC and beyond.

  18. Microstructures of GaN and In{sub x}Ga{sub 1-x}N films grown by MOCVD on free-standing GaN templates

    Energy Technology Data Exchange (ETDEWEB)

    Jasinski, J.; Liliental-Weber, Z.; Huang, D.; Reshchikov, M.A.; Yun, F.; Morkoc, H.; Sone, C.; Park, S.S.; Lee, K.Y.

    2002-04-30

    We summarize structural properties of thick HVPE GaN templates from the point of view of their application as substrates for growth of nitride layers. This is followed by the results of optical and structural studies, mostly transmission electron microscopy, of nitride layers grown by MOCVD on top of the HVPE substrates. The results indicate high structural quality of these layers with a low density of threading dislocations (in the range of 10{sup 6} cm{sup -2}). Convergent beam electron diffraction studies showed that the MOCVD GaN films have Ga-polarity, the same polarity as the HVPE GaN substrates. Structural studies of an InGaN layer grown on top of the MOCVD GaN film showed the presence of two layers, which differed in lattice parameter and composition. The upper layer, on the top of the structure had a c-lattice parameter about 2% larger than that of GaN and contained 10.3 {+-} 0.8% of In. Values measured for the thinner, intermediate layer adjacent to the GaN layer were about 2 .5 times lower.

  19. Top-ophilia

    Energy Technology Data Exchange (ETDEWEB)

    Quigg, Chris; /Fermilab

    2008-01-01

    Almost from the moment in June 1977 when the discovery of the Upsilon resonance revealed the existence of what we now call the bottom quark, physicists began searching for its partner. Through the years, as we established the electric charge and weak isospin of the b-quark, and detected the virtual influence of its mate, it became clear that the top quark must exist. Exactly at what mass, we couldn't say, but we knew just how top events would look. We also knew that top events would be rare--if the Tevatron could make them at all--and that picking out the events would pose a real challenge for the experimenters and their detectors.

  20. TOPS optical correlation program

    Science.gov (United States)

    Lindell, Scott D.

    1993-09-01

    Martin Marietta is conducting a TOPS optical correlation program in which several algorithms and four optical correlators involving two spatial light modulator technologies will be developed and tested. The program will culminate in 1994 with an automatic target recognition flight demonstration using a UH-1 helicopter flying a Fiber Optic Guide Missile (FOG-M) mission profile. The flight demonstration will be conducted by US Army Missile Command (MICOM) and Martin Marietta and will involve detecting, locating and tracking a M60A2 tank positioned among an array of five vehicle types. Current status of the TOPS program will be given.

  1. Freestanding polypyrrole films as counter electrode for low cost dye sensitized solar cells

    Science.gov (United States)

    Jha, P.; Veerender, P.; Koiry, S. P.; Sridevi, C.; Chabbi, Pradnya; Samanta, S.; Chauhan, A. K.; Muthe, K. P.; Gadkari, S. C.

    2017-05-01

    Free standing polypyrrole films were synthesized using aqueous-organic interfacial polymerization. The electrical conductivity of these films was found to be higher when hexane(or benzene)-aqueous biphasic system is used. These high conductivity films were utilized as cost effective counter electrode to replace expansive Platinum in the fabrication of quasi-solid dye sensitized solar cells. The efficiency of DSSC was found to be 1.1%, which is close to that of 1.8% prepared using Pt as counter electrode.

  2. Photonics Academy: TOPS project

    Science.gov (United States)

    Tyson, Nick; Barwis, Vicky; Maghuk, Faris

    2009-06-01

    Technicians in Opto-Electronics Project (TOP) has five targets: one, to develop and pilot train with at least 10 learners; two, to implement a marketing plan; three, to raise awareness of the sector with young people to increase new entrants into the sector; four, to engage employers in development; and five, to provide information on leadership and management.

  3. TOP 10 NATIONAL EVENTS

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    1 Development Goals Defined China’s 12th Five-Year Plan for National Economic and Social Development (2011-15) was approved by the National People’s Congress, the country’s top legislature, on March 14. Focusing on building a green economy, China plans to cut energy consumption and carbon dioxide

  4. The World's Top Choice

    Institute of Scientific and Technical Information of China (English)

    DING WENLEI

    2010-01-01

    @@ China maintained it's top seat as the most attractive destination for global foreign direct investment (FDI),said a report by the United Nations Conference on Trade and Development (UNCTAD)-and it is likely to remain so for the next two years.

  5. Ehitusfirmade TOP / Siim Sultson

    Index Scriptorium Estoniae

    Sultson, Siim

    2007-01-01

    Tabel: Ehitusettevõtete TOP 90. Vt. samas: Käive; Käibe kasv; Kasum; Kasumi kasv; Rentaablus; Omakapitali tootlikkus; TOPi koostamise metoodika; TTP AS andis ka siis tooni; TTP toimetab vaikselt, tõhusalt; Harju Ehitus toetub aastate pikkkusele tööle ning väldib tormakust ja teovõimetust; NCC Ehituse AC tunnetab ehitusturu pulssi positiivselt

  6. Ehitusfirmade TOP / Siim Sultson

    Index Scriptorium Estoniae

    Sultson, Siim

    2007-01-01

    Tabel: Ehitusettevõtete TOP 90. Vt. samas: Käive; Käibe kasv; Kasum; Kasumi kasv; Rentaablus; Omakapitali tootlikkus; TOPi koostamise metoodika; TTP AS andis ka siis tooni; TTP toimetab vaikselt, tõhusalt; Harju Ehitus toetub aastate pikkkusele tööle ning väldib tormakust ja teovõimetust; NCC Ehituse AC tunnetab ehitusturu pulssi positiivselt

  7. Enhanced performance of dye-sensitized solar cells based on TiO2 nanotube membranes using an optimized annealing profile.

    Science.gov (United States)

    Mohammadpour, F; Moradi, M; Lee, K; Cha, G; So, S; Kahnt, A; Guldi, D M; Altomare, M; Schmuki, P

    2015-01-31

    We use free-standing TiO2 nanotube membranes that are transferred onto FTO slides in front-side illuminated dye-sensitized solar cells (DSSCs). We investigate the key parameters for solar cell arrangement of self-ordered anodic TiO2 nanotube layers on the FTO substrate, namely the influence of the annealing procedure on the DSSC light conversion efficiency. The results show that using an optimal temperature annealing profile can significantly enhance the DSSC efficiency (in our case η = 9.8%), as it leads to a markedly lower density of trapping states in the tube oxide, and thus to strongly improved electron transport properties.

  8. Measurement of top quark properties in single top production

    CERN Document Server

    Jafari, Abideh

    2016-01-01

    Single top topologies are exploited for studies of top quark properties. This includes the first measurement of single top polarization in the t-channel production mode in pp collisions, which directly confirms the V-A nature of the tWb production vertex. W-helicity fractions are measured in the phase space sampled by a selection optimized for t-channel single top production, orthogonal to the ttbar final states used in traditional measurements of these properties. Anomalous couplings of the top quark are also searched in t-channel single top production with a NN-based analysis.

  9. Top pair and single top production in ATLAS

    CERN Document Server

    Fabbri, Federica; The ATLAS collaboration

    2017-01-01

    Measurements of inclusive and differential top-quark production cross sections in proton-proton collisions with the ATLAS detector at the Large Hadron Collider are presented at a center of mass energy of 8 TeV and 13 TeV. The inclusive measurements of top quark pair and single top quark production reach high precision and are compared to the best available theoretical calculations. Differential measurements of the kinematic properties of top quark events are also discussed. These measurements, including results using boosted top quarks, probe our understanding of top quark production in the TeV regime.

  10. Naisjuhtidega ettevõtete TOP 100

    Index Scriptorium Estoniae

    2004-01-01

    Naisjuhtidega ettevõtete TOP 100. Käibe TOP 20. Käibe kasvu TOP 20. Kasumi TOP 20. Kasumi kasvu TOP 20. Rentaabluse TOP 20. Omakapitali tootlikkuse TOP 20. Riigi- ja kohaliku omavalitsuse asutuste naisjuhtide TOP 25. Riigi- ja kohaliku omavalitsuse asutuste eelarve TOP 25. Riigi- ja kohaliku omavalitsuse asutuste töötajate arvu TOP 25. Riigi- ja kohaliku omavalitsuse asutuste naisjuhtide palga TOP 25

  11. Naisjuhtidega ettevõtete TOP 100

    Index Scriptorium Estoniae

    2004-01-01

    Naisjuhtidega ettevõtete TOP 100. Käibe TOP 20. Käibe kasvu TOP 20. Kasumi TOP 20. Kasumi kasvu TOP 20. Rentaabluse TOP 20. Omakapitali tootlikkuse TOP 20. Riigi- ja kohaliku omavalitsuse asutuste naisjuhtide TOP 25. Riigi- ja kohaliku omavalitsuse asutuste eelarve TOP 25. Riigi- ja kohaliku omavalitsuse asutuste töötajate arvu TOP 25. Riigi- ja kohaliku omavalitsuse asutuste naisjuhtide palga TOP 25

  12. Top Local Cohomology Modules

    Institute of Scientific and Technical Information of China (English)

    Mohammad T. Dibaei; Siamak Yassemi

    2007-01-01

    For a finitely generated module M over a commutative Noetherian local ring (R, m), it is shown that there exist only a finite number of non-isomorphic top localeohomology modules Hdim(M) (M) for all ideals a of RIt is also shown that for a giveninteger r ≥ 0, if Hra(R/p) is zero for all p in Supp(M), then Hia(M)=0 for all I ≥ r.

  13. Top quark measurements at ATLAS

    CERN Document Server

    Grancagnolo, Sergio; The ATLAS collaboration

    2017-01-01

    The top quark is the heaviest known fundamental particle. As it is the only quark that decays before it hadronizes, this gives us the unique opportunity to probe the properties of bare quarks at the Large Hadron Collider. This talk will present highlights of a few recent precision measurements by the ATLAS Collaboration of the top quark using 13 TeV and 8 TeV collision data: top-quark pair and single top production cross sections including differential distributions will be presented alongside top quark properties measurements. These measurements, including results using boosted top quarks, probe our understanding of top quark production in the TeV regime. Measurements of the top quark mass and searches for rare top quark decays are also presented.

  14. Four tops for LHC

    Science.gov (United States)

    Alvarez, Ezequiel; Faroughy, Darius A.; Kamenik, Jernej F.; Morales, Roberto; Szynkman, Alejandro

    2017-02-01

    We design a search strategy for the Standard Model t t bar t t bar production at the LHC in the same-sign dilepton and trilepton channels. We study different signal features and, given the small expected number of signal events, we scrutinize in detail all reducible and irreducible backgrounds. Our analysis shows that by imposing a basic set of jet and lepton selection criteria, the SM pp → t t bar t t bar process could be evidenced in the near future, within Run-II, when combining both multi-lepton search channels. We argue that this search strategy should also be used as a guideline to test New Physics coupling predominantly to top-quarks. In particular, we show that a non-resonant New Physics enhancement in the four-top final state would be detectable through this search strategy. We study two top-philic simplified models of this kind, a neutral scalar boson and a Z‧, and present current and future exclusion limits on their mass and couplings.

  15. Four Tops for LHC

    CERN Document Server

    Alvarez, Ezequiel; Kamenik, Jernej F; Morales, Roberto; Szynkman, Alejandro

    2016-01-01

    We design a search strategy for the Standard Model $t\\bar t t \\bar t$ production at the LHC in the same-sign dilepton and trilepton channels. We study different signal features and, given the small expected number of signal events, we scrutinize in detail all reducible and irreducible backgrounds. Our analysis shows that by imposing a set of basic jet and lepton selection criteria, the SM $pp \\to t\\bar t t \\bar t$ process could be evidenced in the near future, within Run-II, when combining both multi-lepton search channels. We argue that this search strategy should also be used as a guideline to test New Physics coupling predominantly to top-quarks. In particular, we show that a non-resonant New Physics enhancement of the four-top final state would be detectable through this search strategy. We study two {\\it top-philic} simplified models of this kind, a neutral scalar boson and a $Z^\\prime$, and present current and future exclusion limits on their mass and couplings.

  16. Top quark properties in ATLAS

    CERN Document Server

    Demilly, A; The ATLAS collaboration

    2014-01-01

    Properties of the top quark are measured with the ATLAS detector using LHC proton-proton collisions data. Measurements of the top-quark mass and polarisation, as well as of the polarization of W bosons in top quark decays to probe the Wtb-vertex are presented. In addition, measurements of the spin correlation between top and anti-top quarks as well as of the top- quark charge asymmetry, which constitute important tests of QCD and are sensitive to new physics, are discussed.

  17. Ultrathin, flexible organic-inorganic hybrid solar cells based on silicon nanowires and PEDOT:PSS.

    Science.gov (United States)

    Sharma, Manisha; Pudasaini, Pushpa Raj; Ruiz-Zepeda, Francisco; Elam, David; Ayon, Arturo A

    2014-03-26

    Recently, free-standing, ultrathin, single-crystal silicon (c-Si) membranes have attracted considerable attention as a suitable material for low-cost, mechanically flexible electronics. In this paper, we report a promising ultrathin, flexible, hybrid solar cell based on silicon nanowire (SiNW) arrays and poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS). The free-standing, ultrathin c-Si membranes of different thicknesses were produced by KOH etching of double-side-polished silicon wafers for various etching times. The processed free-standing silicon membranes were observed to be mechanically flexible, and in spite of their relatively small thickness, the samples tolerated the different steps of solar cell fabrication, including surface nanotexturization, spin-casting, dielectric film deposition, and metallization. However, in terms of the optical performance, ultrathin c-Si membranes suffer from noticeable transmission losses, especially in the long-wavelength region. We describe the experimental performance of a promising light-trapping scheme in the aforementioned ultrathin c-Si membranes of thicknesses as small as 5.7 μm employing front-surface random SiNW texturization in combination with a back-surface distribution of silver (Ag) nanoparticles (NPs). We report the enhancement of both the short-circuit current density (JSC) and the open-circuit voltage (VOC) that has been achieved in the described devices. Such enhancement is attributable to the plasmonic backscattering effect of the back-surface Ag NPs, which led to an overall 10% increase in the power conversion efficiency (PCE) of the devices compared to similar structures without Ag NPs. A PCE in excess of 6.62% has been achieved in the described devices having a c-Si membrane of thickness 8.6 μm. The described device technology could prove crucial in achieving an efficient, low-cost, mechanically flexible photovoltaic device in the near future.

  18. Tekstiilitööstuse TOP 47

    Index Scriptorium Estoniae

    2005-01-01

    Tekstiilitööstuse TOP 47; Käibe TOP 35; Kasumi TOP 35; Käibe kasvu TOP 20; Kasumi kasvu TOP 20; Rentaabluse TOP 20; Varade tootlikkuse TOP 20; Tekstiilitööstuse TOP-i firmade üld- ja finantsandmed

  19. Eesti Ettevõtete TOP 100

    Index Scriptorium Estoniae

    2002-01-01

    TOP 100. Käibe TOP 500. Käibe kasvu TOP 100. Kasumi TOP 100. Kasumi kasvu TOP 100. Rentaabluse TOP 100. Omakapitali tootlikkuse TOP 100. Eesti edukamate ettevõtete üldandmed. Eesti edukamate ettevõtete finantsnäitajad. Valdkonna ja maakonna TOP-ide edukamate ettevõtete finantsnäitajad

  20. Rõivatööstuse TOP 50

    Index Scriptorium Estoniae

    2005-01-01

    Rõivatööstuse TOP 50; Käibe TOP 35; Kasumi TOP 35; Käibe kasvu TOP 20; Kasumi kasvu TOP 20; Rentaabluse TOP 20; Omakapitali tootlikkuse TOP 20; Rõivatööstuse TOP-i firmade üld- ja finantsandmed

  1. Tekstiilitööstuse TOP 47

    Index Scriptorium Estoniae

    2005-01-01

    Tekstiilitööstuse TOP 47; Käibe TOP 35; Kasumi TOP 35; Käibe kasvu TOP 20; Kasumi kasvu TOP 20; Rentaabluse TOP 20; Varade tootlikkuse TOP 20; Tekstiilitööstuse TOP-i firmade üld- ja finantsandmed

  2. Rõivatööstuse TOP 50

    Index Scriptorium Estoniae

    2005-01-01

    Rõivatööstuse TOP 50; Käibe TOP 35; Kasumi TOP 35; Käibe kasvu TOP 20; Kasumi kasvu TOP 20; Rentaabluse TOP 20; Omakapitali tootlikkuse TOP 20; Rõivatööstuse TOP-i firmade üld- ja finantsandmed

  3. Eesti Ettevõtete TOP 100

    Index Scriptorium Estoniae

    2002-01-01

    TOP 100. Käibe TOP 500. Käibe kasvu TOP 100. Kasumi TOP 100. Kasumi kasvu TOP 100. Rentaabluse TOP 100. Omakapitali tootlikkuse TOP 100. Eesti edukamate ettevõtete üldandmed. Eesti edukamate ettevõtete finantsnäitajad. Valdkonna ja maakonna TOP-ide edukamate ettevõtete finantsnäitajad

  4. Treasury Offset Program (TOP) MI

    Data.gov (United States)

    Social Security Administration — The TOP MI helps OPSOS coordinate TOP case processing in the regions. The MI also helped communicate our progress and findings to BFQM and ORDP, as well as the ACOSS.

  5. Top physics results with ATLAS

    CERN Document Server

    Massa, Lorenzo; The ATLAS collaboration

    2015-01-01

    This paper contains some of the most recent results on top-quark physics obtained by the ATLAS collaboration from the analysis of $pp$ collisions at $\\sqrt{s}=7$ TeV and 8 TeV at the Large Hadron Collider. Measurement of total and differential top-quark pair ($t\\bar{t}$), single top and $t\\bar{t}+\\gamma$ production cross sections and some top properties like mass, charge asymmetry and spin correlation are presented.

  6. Combined solar unit

    Energy Technology Data Exchange (ETDEWEB)

    Bayramov, R.B.; Nazarova, G.R.; Pivovarova, A.P.; Ushakova, A.D.

    1982-01-01

    In order to improve the effectiveness of using solar energy, the collector containing the loops for heat and cold supply is equipped with a corrugated regenerator installed under the boiler, and the latter is made in the form of a coil arranged at the top of the regenerator crimping.

  7. Top physics results at CDF

    Energy Technology Data Exchange (ETDEWEB)

    Vickey, Trevor; /Illinois U., Urbana

    2005-05-01

    The most recent results on top quark physics at CDF are reported. Measurements of cross-section and mass are presented, and the status of single top quark production searches are discussed. The results obtained from probing various top quark properties are also presented.

  8. Fiber-top micromachined devices

    NARCIS (Netherlands)

    Iannuzzi, D.; De Man, S.; Alberts, C.J.; Berenschot, Johan W.; Elwenspoek, Michael Curt; Said, A.A.; Dugan, M.

    2008-01-01

    After a general review on fiber-top technology, we will present our recent achievements in the utilization of fiber-top double-clamped cantilevers as refractometers and in the development of alternative techniques for the fabrication of fiber-top devices.

  9. Top physics results at CDF

    Energy Technology Data Exchange (ETDEWEB)

    Vickey, Trevor; /Illinois U., Urbana

    2005-05-01

    The most recent results on top quark physics at CDF are reported. Measurements of cross-section and mass are presented, and the status of single top quark production searches are discussed. The results obtained from probing various top quark properties are also presented.

  10. General Top-Down Ion Exchange Process for the Growth of Epitaxial Chalcogenide Thin Films and Devices

    KAUST Repository

    Xia, Chuan

    2016-12-30

    We demonstrate a versatile top-down ion exchange process, done at ambient temperature, to form epitaxial chalcogenide films and devices, with nanometer scale thickness control. To demonstrate the versatility of our process we have synthesized (1) epitaxial chalcogenide metallic and semiconducting films and (2) free-standing chalcogenide films and (3) completed in situ formation of atomically sharp heterojunctions by selective ion exchange. Epitaxial NiCo2S4 thin films prepared by our process show 115 times higher mobility than NiCo2S4 pellets (23 vs 0.2 cm(2) V-1 s(-1)) prepared by previous reports. By controlling the ion exchange process time, we made free-standing epitaxial films of NiCo2S4 and transferred them onto different substrates. We also demonstrate in situ formation of atomically sharp, lateral Schottky diodes based on NiCo2O4/NiCo2S4 heterojunction, using a single ion exchange step. Additionally, we show that our approach can be easily extended to other chalcogenide semiconductors. Specifically, we used our process to prepare Cu1.8S thin films with mobility that matches single crystal Cu1.8S (25 cm(2) V-1 s(-1)), which is ca. 28 times higher than the previously reported Cu1.8S thin film mobility (0.58 cm(2) V-1 s(-1)), thus demonstrating the universal nature of our process. This is the first report in which chalcogenide thin films retain the epitaxial nature of the precursor oxide films, an approach that will be useful in many applications.

  11. Top quark pair production and top quark properties at CDF

    Energy Technology Data Exchange (ETDEWEB)

    Moon, Chang-Seong [INFN, Pisa

    2016-06-02

    We present the most recent measurements of top quark pairs production and top quark properties in proton-antiproton collisions with center-of-mass energy of 1.96 TeV using CDF II detector at the Tevatron. The combination of top pair production cross section measurements and the direct measurement of top quark width are reported. The test of Standard Model predictions for top quark decaying into $b$-quarks, performed by measuring the ratio $R$ between the top quark branching fraction to $b$-quark and the branching fraction to any type of down quark is shown. The extraction of the CKM matrix element $|V_{tb}|$ from the ratio $R$ is discussed. We also present the latest measurements on the forward-backward asymmetry ($A_{FB}$) in top anti-top quark production. With the full CDF Run II data set, the measurements are performed in top anti-top decaying to final states that contain one or two charged leptons (electrons or muons). In addition, we combine the results of the leptonic forward-backward asymmetry in $t\\bar t$ system between the two final states. All the results show deviations from the next-to-leading order (NLO) standard model (SM) calculation.

  12. Toiduainetööstuste TOP 100

    Index Scriptorium Estoniae

    2006-01-01

    Toiduainetööstuse TOP. Vt. samas: Käibe TOP 10; Käibekasvu TOP 10; Kasumi TOP 10; Kasumi kasvu TOP 10; Rentaabluse TOP 10; Omakapitali tootlikkuse TOP 10; Toiduainetööstuse üld- ja finantsandmed

  13. Online-kaubanduse TOP aastal 2003

    Index Scriptorium Estoniae

    2004-01-01

    Online-kaubanduse TOP aastal 2003. Käibe TOP 5. Käibe kasvu TOP 5. Rentaabluse TOP 5. Kasumi TOP 5. Kasumi kasvu TOP 5. Omakapitali tootlikkuse TOP 5. Lisa: TOPi koostamise metoodika. Online-kaubanduse firmade üldandmed. Online kaubanduse firmade finantsandmed

  14. Online-kaubanduse TOP aastal 2003

    Index Scriptorium Estoniae

    2004-01-01

    Online-kaubanduse TOP aastal 2003. Käibe TOP 5. Käibe kasvu TOP 5. Rentaabluse TOP 5. Kasumi TOP 5. Kasumi kasvu TOP 5. Omakapitali tootlikkuse TOP 5. Lisa: TOPi koostamise metoodika. Online-kaubanduse firmade üldandmed. Online kaubanduse firmade finantsandmed

  15. Hiiumaa ettevõtete TOP 50

    Index Scriptorium Estoniae

    2005-01-01

    Hiiumaa ettevõtete TOP 50; Käibe TOP 35; Kasumi TOP 35; Hiiumaa ettevõtete üld- ja finantsandmed; Käibe kasvu TOP 20; Kasumi kasvu TOP 20; Rentaabluse TOP 20; Omakapitali tootlikkuse TOP 20. Vt samas: Teeli Remmalg: Hiiumaal jätkub plastitööstuse võidumarss

  16. Harjumaa ettevõtete TOP aastal 2002

    Index Scriptorium Estoniae

    2003-01-01

    Harjumaa ettevõtete TOP 100. Käibe kasvu TOP 25. Kasumi kasvu TOP 25. Rentaabluse TOP 25. Omakapitali tootlikkuse TOP 25. Käibe TOP 50. Kasumi TOP 50. Harjumaa ettevõtted 2002: üldandmed. Harjumaa ettevõtted 2002: finantsandmed

  17. Hiiumaa ettevõtete TOP 50

    Index Scriptorium Estoniae

    2005-01-01

    Hiiumaa ettevõtete TOP 50; Käibe TOP 35; Kasumi TOP 35; Hiiumaa ettevõtete üld- ja finantsandmed; Käibe kasvu TOP 20; Kasumi kasvu TOP 20; Rentaabluse TOP 20; Omakapitali tootlikkuse TOP 20. Vt samas: Teeli Remmalg: Hiiumaal jätkub plastitööstuse võidumarss

  18. Harjumaa ettevõtete TOP aastal 2002

    Index Scriptorium Estoniae

    2003-01-01

    Harjumaa ettevõtete TOP 100. Käibe kasvu TOP 25. Kasumi kasvu TOP 25. Rentaabluse TOP 25. Omakapitali tootlikkuse TOP 25. Käibe TOP 50. Kasumi TOP 50. Harjumaa ettevõtted 2002: üldandmed. Harjumaa ettevõtted 2002: finantsandmed

  19. Naisjuhtidega ettevõtete TOP 100

    Index Scriptorium Estoniae

    2006-01-01

    Ettevõtete TOP 100. Vt. samas: Käibe TOP 15; Käibe kasvu TOP 15; Majandustegevuse kasumi TOP 15; Kasumi kasvu TOP 15; Rentaabluse TOP15; Omakapitali tootlikkuse TOP15; Naisjuhtidega ettevõtete üld- ja finantsandmed

  20. Toiduainetööstuste TOP 100

    Index Scriptorium Estoniae

    2006-01-01

    Toiduainetööstuse TOP. Vt. samas: Käibe TOP 10; Käibekasvu TOP 10; Kasumi TOP 10; Kasumi kasvu TOP 10; Rentaabluse TOP 10; Omakapitali tootlikkuse TOP 10; Toiduainetööstuse üld- ja finantsandmed

  1. The search for the top quark

    Energy Technology Data Exchange (ETDEWEB)

    Barbaro-Galtieri, A.

    1989-03-01

    This paper discusses the following topics: top search in the near future, general remarks, top search at HERA, searching for the top quarks at the Z/sup 0/ machines, finding the top at Lep II, top search in UA2, top search in UA1, and top search at CDF. 58 refs., 38 figs.

  2. Top quark physics

    Energy Technology Data Exchange (ETDEWEB)

    Menzione, A. [INFN Sezione di Pisa (Italy)

    1995-10-01

    Most of the material presented in this report, comes from contributions to the parallel session PL20 of this conference. We summarise the experimental results of direct production of Top quarks, coming from the CDF and C0 Collaborations at Fermilab, and compare these results to what one expects within current theoretical understanding. Particular attention is given to new results such as all hadronic modes of t{bar t} decay. As far as the mass is concerned, a comparison is made with precision measurements of related quantities, coming from LEP and other experiments. An attempt is made to look at the medium-term future and understand which variables and with what accuracy one can measure them with increased integrated luminosity.

  3. Top-Higgs and top-pion phenomenology in the top triangle moose model

    Science.gov (United States)

    Chivukula, R. Sekhar; Simmons, Elizabeth H.; Coleppa, Baradhwaj; Logan, Heather E.; Martin, Adam

    2011-03-01

    We discuss the deconstructed version of a topcolor-assisted technicolor model wherein the mechanism of top quark mass generation is separated from the rest of electroweak symmetry breaking. The minimal deconstructed version of this scenario is a “triangle moose” model, where the top quark gets its mass from coupling to a top-Higgs field, while the gauge boson masses are generated from a Higgsless sector. The spectrum of the model includes scalar (top-Higgs) and pseudoscalar (top-pion) states. In this paper, we study the properties of these particles, discuss their production mechanisms and decay modes, and suggest how best to search for them at the LHC.

  4. Top-Higgs and Top-pion phenomenology in the Top Triangle Moose model

    CERN Document Server

    Chivukula, R Sekhar; Logan, Heather E; Martin, Adam; Simmons, Elizabeth H

    2011-01-01

    We discuss the deconstructed version of a topcolor-assisted technicolor model wherein the mechanism of top quark mass generation is separated from the rest of electroweak symmetry breaking. The minimal deconstructed version of this scenario is a "triangle moose" model, where the top quark gets its mass from coupling to a top-Higgs field, while the gauge boson masses are generated from a Higgsless sector. The spectrum of the model includes scalar (top-Higgs) and pseudoscalar (top-pion) states. In this paper, we study the properties of these particles, discuss their production mechanisms and decay modes, and suggest how best to search for them at the LHC.

  5. Solar Indices - Solar Corona

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Collection includes a variety of indices related to solar activity contributed by a number of national and private solar observatories located worldwide. This...

  6. Solar Indices - Solar Flares

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Collection includes a variety of indices related to solar activity contributed by a number of national and private solar observatories located worldwide. This...

  7. Solar Indices - Solar Irradiance

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Collection includes a variety of indices related to solar activity contributed by a number of national and private solar observatories located worldwide. This...

  8. Solar Indices - Solar Ultraviolet

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Collection includes a variety of indices related to solar activity contributed by a number of national and private solar observatories located worldwide. This...

  9. Naisjuhtidega ettevõtete TOP 70

    Index Scriptorium Estoniae

    2003-01-01

    Naisjuhtidega ettevõtete TOP 70. Käibe TOP 30. Käibe kasvu TOP 30. Kasumi TOP 30. Kasumi kasvu TOP 30. Rentaabluse TOP 30. Omakapitali tootlikkuse TOP 30. Nais- ja meesjuhtidega ettevõtted 2001. aasta 500 edukama ettevõtte hulgas. Naistegevjuhtidega firmade TOP 2001 ja 2002. Riigi- ja kohaliku omavalitsuse asutuste naisjuhtide TOP 20. Riigi- ja kohaliku omavalitsuse asutuste eelarve TOP 20. Riigi- ja kohaliku omavalitsuse asutuste töötajate arvu TOP 20. Naistegevjuhtidega firmade osakaal 2001. aastal. Riigi- ja kohaliku omavalitsuse asutuste naisjuhtide aastapalga TOP 20. Kommenteerib Tiina Raitviir.

  10. Naisjuhtidega ettevõtete TOP 70

    Index Scriptorium Estoniae

    2003-01-01

    Naisjuhtidega ettevõtete TOP 70. Käibe TOP 30. Käibe kasvu TOP 30. Kasumi TOP 30. Kasumi kasvu TOP 30. Rentaabluse TOP 30. Omakapitali tootlikkuse TOP 30. Nais- ja meesjuhtidega ettevõtted 2001. aasta 500 edukama ettevõtte hulgas. Naistegevjuhtidega firmade TOP 2001 ja 2002. Riigi- ja kohaliku omavalitsuse asutuste naisjuhtide TOP 20. Riigi- ja kohaliku omavalitsuse asutuste eelarve TOP 20. Riigi- ja kohaliku omavalitsuse asutuste töötajate arvu TOP 20. Naistegevjuhtidega firmade osakaal 2001. aastal. Riigi- ja kohaliku omavalitsuse asutuste naisjuhtide aastapalga TOP 20. Kommenteerib Tiina Raitviir.

  11. Boosted Top Quarks, Top Pair Resonances, and Top Partner Searches at the LHC

    Directory of Open Access Journals (Sweden)

    Pilot Justin

    2013-11-01

    Full Text Available The increased center-of-mass energy of proton-proton collisions at the LHC allows for higher and higher mass scales to be probed in the search for new physics. These searches for new physics can often involve the reconstruction of top quark decays. In this high-mass regime, event topologies can change and top quark decay products become highly boosted, requiring the use of special identification algorithms. This report summarizes the latest techniques used in the reconstruction of boosted top quarks, and highlights several new physics searches from ATLAS and CMS where they are utilized. Such analyses include the search for top quark pair resonances as is expected from Z’ decays, as well as top quark partner searches, such as fourth generation vector-like quarks, excited top quarks, and top quark partners with non-standard charges

  12. Boosted Top Quarks, Top Pair Resonances, and Top Partner Searches at the LHC

    CERN Document Server

    Pilot, Justin Robert

    2013-01-01

    The increased center-of-mass energy of proton-proton collisions at the LHC allows for higher and higher mass scales to be probed in the search for new physics. These searches for new physics can often involve the reconstruction of top quark decays. In this high-mass regime, event topologies can change and top quark decay products become highly boosted, requiring the use of special identification algorithms. This report summarizes the latest techniques used in the reconstruction of boosted top quarks, and highlights several new physics searches from ATLAS and CMS where they are utilized. Such analyses include the search for top quark pair resonances as is expected from $Z^{\\prime}$ decays, as well as top quark partner searches, such as fourth generation vector-like quarks, excited top quarks, and top quark partners with non-standard charges.

  13. Top mass reconstruction in ATLAS

    CERN Document Server

    Neusiedl, A; The ATLAS collaboration

    2011-01-01

    The top-quark mass is a fundamental parameter of the Standard Model. After the discovery of the top quark, the measurements of its properties were of substantial interest. Within the framework of the SM, the top-quark mass can be used in combination with other electroweak precision measurements to constrain the mass of the yet unobserved Higgs boson.\\\\ In the new era of the Large Hadron Collider (LHC), the first top quarks have been produced in Europe in proton-proton collisions at a center-of-mass energy of 7~TeV. The top-quark mass measurement of ATLAS in the so called lepton+jets channel with 35~pb$^{-1}$ integrated luminosity is presented. In this early data-taking period the largest uncertainty on this measurement comes from the knowledge of the jet energy scale. It is shown how this uncertainty is determined and which methods are used for measuring the top-quark mass.

  14. 自持TiO2纳米管阵列薄膜与TiO2/FTO透明光电极制备工艺的研究%INVESTIGATION OF THE FABRICATED TECHNOLOGY OF FREE-STANDING TIO2 NANOTUBE MEMBRANES AND TIO2/FTO TRANSPARENT PHOTOELECTRODE

    Institute of Scientific and Technical Information of China (English)

    张其君; 李燕; 赵雲; 王多书; 王成伟

    2011-01-01

    利用电化学阳极氧化法,采用三步氧化工艺,成功制备出大面积高度有序、孔洞分布均匀、孔道垂直取向且与金属钛基相分离的自持TiO2纳米管阵列膜.然后将其转移粘接至FTO导电玻璃上,形成高度有序的TiO2/FTO纳米管阵列透明光电极.利用场发射扫描电镜、X射线衍射仪、紫外-可见-近红外分光光度计分别对样品的形貌、晶相结构以及光学特性做了表征.研究表明,由三步阳极氧化工艺制备的自持TiO2纳米管阵列膜,其结构参数(如管径、管长及管壁厚度)在很大范围内可控,将其转移粘结至FTO导电玻璃上能制成多种用途的高质量透明光电极;另外,阳极氧化电压对TiO2纳米管阵列薄膜的光学能隙(Eg)也有较为明显的调制作用.显然,这项新工艺对基于TiO2纳米有序阵列复合结构的有机-无机光电器件的应用研究将是非常有益的.%The large-scale, highly-ordered, vertically-oriented free-standing TiO2 nanotube membranes were fabricated by three step anodization Ti foils in ethylene glycol containing 0.25w (NH4F)%. Then the as-prepared free-standing membranes were transferred to FTO-coated glass substrates with TiO2 sol, and the transparent TiO3/FTO photoelectrode was obtained after annealing treatment. The morphologies, crystalline phase, optical properties were characterized using FE-SEM, XRD and UV-Vis-NIR spectrophotometer, respectively. To some extent, the structural parameters of the free-standing TiO2 nanotube membranes (inner diameter, nanotube length, and wall thickness)are controllable. After the membranes were transferred onto the FTO-coated glass substrate, we can obtain the high quality and multi-application TiO3/FTO photoelectrode At the same time, it is found that the optical energy gap(Eg) of TiO2 nanotube membranes could be effectively modulated by different anodic oxidation voltage. Obviously, this work would be beneficial to apply in organic

  15. Top Quark Physics: Future Measurements

    Energy Technology Data Exchange (ETDEWEB)

    Jaros, John A

    2003-05-09

    We discuss the study of the top quark at future experiments and machines. Top's large mass makes it a unique probe of physics at the natural electroweak scale. We emphasize measurements of the top quark's mass, width, and couplings, as well as searches for rare or nonstandard decays, and discuss the complementary roles played by hadron and lepton colliders.

  16. Participative Design With Top Management

    DEFF Research Database (Denmark)

    Simonsen, Jesper

    2004-01-01

    meetings aimed at aligning top management with the supplier’s analysis. The article describes the MUST method’s anchoring principle and the technique of problem mapping supporting this principle. This participatory approach resulted in mutual learning processes with top management which is rarely reported...... on in the PD community. Top management participated by reviewing, challenging, and reformulating the IT designers’ central suppositions, assumptions, and hypotheses related to the causal relation between identified problems and suggested solutions....

  17. Our top priority

    CERN Document Server

    2012-01-01

    After three years of LHC running, we are still at the beginning of a long research programme with our flagship facility, and hopefully 4 July 2012 will go down in history as the date of one of many landmark discoveries spanning several years. CERN’s top priority for the next decade and more is the full exploitation of the LHC. With speculation about potential future facilities mounting in the light of the discovery of a new Higgs-like particle, it’s important to state that most clearly. Of course, this will rely on continued global collaboration, and it’s important that CERN engage constructively with other regions.   It is important to plan ahead, particularly since the lead times for new projects in particle physics are long, and our field is increasingly global in nature. That’s why the European particle physics community is currently engaged in updating its long-term strategy. Planning ahead allowed us to be ready technologically to build the LHC whe...

  18. Top Quark Current Experimental Status

    CERN Document Server

    Juste, A

    2006-01-01

    Ten years after its discovery at the Tevatron collider, we still know little about the top quark. Its large mass suggests it may play a key role in the mechanism of Electroweak Symmetry Breaking (EWSB), or open a window of sensitivity to new physics related to EWSB and preferentially coupled to it. To determine whether this is the case, precision measurements of top quark properties are necessary. The high statistics samples being collected by the Tevatron experiments during Run II start to incisively probe the top quark sector. This report summarizes the experimental status of the top quark, focusing in particular on the recent measurements from the Tevatron.

  19. Top production at hadron colliders

    Indian Academy of Sciences (India)

    Albert De Roeck

    2012-10-01

    New results on top quark production are presented from four hadron collider experiments: CDF and D0 at the Tevatron, and ATLAS and CMS at the LHC. Cross-sections for single top and top pair production are discussed, as well as results on the top–antitop production asymmetry and searches for new physics including top quarks. The results are based on data samples of up to 5.4 fb-1 for the Tevatron experiments and 1.1 fb−1 for the LHC experiments.

  20. Solar building

    OpenAIRE

    Zhang, Luxin

    2014-01-01

    In my thesis I describe the utilization of solar energy and solar energy with building integration. In introduction it is also mentioned how the solar building works, trying to make more people understand and accept the solar building. The thesis introduces different types of solar heat collectors. I compared the difference two operation modes of solar water heating system and created examples of solar water system selection. I also introduced other solar building applications. It is conv...

  1. Properties of the Top Quark

    Energy Technology Data Exchange (ETDEWEB)

    Déliot, Frédéric [IRFU, Saclay; Hadley, Nicholas [Maryland U., College Park; Parke, Stephen [Fermilab; Schwarz, Tom [Michigan U.

    2014-10-01

    The top quark is the heaviest known elementary particle, and it is often seen as a window to search for new physics processes in particle physics. A large program to study the top-quark properties has been performed both at the Tevatron and LHC colliders by the D0, CDF, ATLAS and CMS experiments. The most recent results are discussed in this article.

  2. Naturalness from a Composite Top?

    CERN Document Server

    Pierce, Aaron

    2016-01-01

    We consider a theory with composite top quarks but an elementary Higgs boson. The hierarchy problem can be solved by supplementing TeV scale top compositeness with either supersymmetry or Higgs compositeness appearing at the multi-TeV scale. The Higgs boson couples to uncolored partons within the top quark. We study how this approach can give rise to a novel screening effect that suppresses production of the colored top partners at the LHC. Strong constraints arise from Z to bb, as well potentially from flavor physics. Independent of flavor considerations, current constraints imply a compositeness scale near a TeV; this implies that the model is likely tuned at the percent level. Four top quark production at the LHC is a smoking-gun probe of this scenario. New CP violation in D meson mixing is also possible.

  3. Status of the top quark: Top production cross section and top properties

    Energy Technology Data Exchange (ETDEWEB)

    Boisvert, V.; /Rochester U.

    2006-08-01

    This report describes the latest cross section and property measurements associated with the top quark at the Tevatron Run II. The largest data sample used is 760 pb{sup -1} of integrated luminosity. Due to its large mass, the top quark might be involved in the process of electroweak symmetry breaking, making it a useful probe for signs of new physics.

  4. Status of the top quark: Top production cross section and top properties

    Energy Technology Data Exchange (ETDEWEB)

    Boisvert, V.; /Rochester U.

    2006-08-01

    This report describes the latest cross section and property measurements associated with the top quark at the Tevatron Run II. The largest data sample used is 760 pb{sup -1} of integrated luminosity. Due to its large mass, the top quark might be involved in the process of electroweak symmetry breaking, making it a useful probe for signs of new physics.

  5. New directions in top physics

    Energy Technology Data Exchange (ETDEWEB)

    Schell, Torben Karl

    2017-02-01

    The top quark plays an important role for many aspects of particle physics. The coupling of the Higgs boson to top quarks is a key parameter to probe electroweak symmetry breaking and is important for the evolution of the Higgs potential to high energies. In addition, many models of physics beyond the Standard Model predict heavy particles that decay to top-quark pairs. Furthermore, the unexplained hierarchy of fermion masses culminates in the large top-quark mass. In this thesis, we consider resonance searches based on top quarks in the fully hadronic final state. We employ multivariate techniques in form of boosted decision trees and add several improvements to the original HEPTopTagger algorithm. These modifications and extensions result in the new HEPTopTagger2. The achieved improvements are used to estimate the precision to which the top Yukawa coupling can be measured at a future 100 TeV proton-proton collider in the fully hadronic final state of t anti tH production. We find that at such a collider a precision measurement of the top Yukawa coupling to 1% should be possible. The statistical precision is backed up by demonstrating that in the ratio σ(t anti tH)/σ(t anti tZ) theoretical uncertainties cancel to below-percent level. Finally, we propose a Froggatt-Nielsen-type model to address the hierarchy of fermion masses in the Standard Model and determine current and projected bounds on the available parameter space.

  6. Properties of the top quark

    Energy Technology Data Exchange (ETDEWEB)

    Jung, A. W. [Fermilab

    2014-09-24

    Recent measurements of top-quark properties at the LHC and the Tevatron are presented. Most recent measurements of the top quark mass have been carried out by CMS using $19.7/$fb of $\\sqrt{s} = 8$ TeV data including the study of the dependence on event kinematics. ATLAS uses the full Run I data at $\\sqrt{s} = 7$ TeV for a "3D" measurement that significantly reduces systematic uncertainties. D0 employs the full Run II data using the matrix element method to measure the top quark mass with significantly reduced systematic uncertainties. Many different measurements of the top quark exist to date and the most precise ones per decay channel per experiment have been combined into the first world combination with a relative precision of 0.44%. Latest updates of measurements of production asymmetries include the measurement of the \\ttbar production asymmetry by D0 employing the full Run II data set, by CMS and ATLAS (including the polarization of the top quark) employing both the full data set at $\\sqrt{s} = 7$ TeV. CMS uses the full $\\sqrt{s} = 8$ TeV data to measure the top quark polarization in single top production, the ratio ${\\cal R}$ of the branching fractions ${\\cal B}(t \\rightarrow Wb) / {\\cal B}(t \\rightarrow Wq)$ and to search for flavor changing neutral currents. The results from all these measurements agree well with their respective Standard Model expectation.

  7. Better Hadronic Top Quark Polarimetry

    CERN Document Server

    Tweedie, Brock

    2014-01-01

    Observables sensitive to top quark polarization are important for characterizing or even discovering new physics. The most powerful spin analyzer in top decay is the down-type fermion from the W, which in the case of leptonic decay allows for very clean measurements. However, in many applications it is useful to measure the polarization of hadronically decaying top quarks. Usually it is assumed that at most 50% of the spin analyzing power can be recovered in this case. This paper introduces a simple and truly optimal hadronic spin analyzer, with a power of 64% at leading-order. The improvement is demonstrated to be robust in a handful of simulated measurements, including the spins and spin correlations of boosted top quarks from multi-TeV top-antitop resonances, the spins of semi-boosted tops from chiral stop decays, and the potentially CP-violating spin correlations induced in continuum top pairs by color dipole operators. For the boosted studies, we explore jet substructure techniques that exhibit improved ...

  8. Free-standing palladium-nickel alloy wavy nanosheets

    Institute of Scientific and Technical Information of China (English)

    Weng-Chon Cheong; Chuhao Liu; Menglei Jiang; Haohong Duan; Dingsheng Wang; Chen Chen; Yadong Li

    2016-01-01

    Two-dimensional nanomaterials (2DNMs) have attracted increasing attention due to their unique properties and promising applications.Unlike 2DNMs with lamellar structures,metal ultrathin 2DNMs are difficult to synthesize and stabilize because they tend to form close-packed crystal structures.Most reported cases consist of monometallic and heterogeneous nanostructures.The synthesis of metal alloy 2DNMs has been rarely reported.Here,we report the synthesis of PdNi alloy wavy nanosheets (WNSs) using an enhanced CO-confinement strategy.This strategy is also suitable to the synthesis of other Pd-based alloy WNSs such as PdCu,PdFe,and even a trimetallic PdFeNi.

  9. Supported and Free-Standing 2D Semimetals

    Science.gov (United States)

    2015-01-15

    Akinwande. Temperature dependence of the electrical resistivity of LaxLu1-xAs, AIP Advances , (08 2013): 0. doi: 10.1063/1.4817830 E. M. Krivoy, H. P...Michael, S. R. Bank, and D. Akinwande, "Temperature dependence of the electrical resistivit y of La [sub x]Lu [sub 1-x]As," AlP Advances , vo l. 3, pp

  10. Preparation of free-standing high quality mesoporous carbon membranes

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xiqing [ORNL; Liang, Chengdu [ORNL; Dai, Sheng [ORNL; Mahurin, Shannon Mark [ORNL; Zhu, Qing [ORNL

    2010-01-01

    Flat-sheet mesoporous carbon membranes with uniform pore size (e.g., 6.4 nm) and controllable thickness were prepared by pyrolysis of polymeric composite films, which were formed by self-assembly of phenolic resin and block copolymer under acidic conditions. Hexamethylenetetramine was selected as a solid cross-linker to control the rheology of polymeric carbon precursors so that the flat-sheet polymeric films could undergo carbonization without deformation, ensuring the preparation of mesoporous carbon membranes on a large scale with high quality. Gas transport properties through these mesoporous carbon membranes are also reported.

  11. Free standing bulk metallic glass microcomponents: Tooling considerations

    DEFF Research Database (Denmark)

    Byrne, Cormac; Eldrup, Morten Mostgaard; Ohnuma, Masato

    2010-01-01

    and mechanical locking. Several solutions to this extraction problem were explored, including high temperature extraction, lubrication and the use of materials with low coefficients of thermal expansion (CTE) as die/mold materials. We show that the use of appropriately chosen low CTE die materials offers...

  12. Võrumaa ettevõtete TOP 50 aastal 2003

    Index Scriptorium Estoniae

    2004-01-01

    Võrumaa ettevõtete TOP 50 aastal 2003. Käibe TOP 40. Kasumi TOP 40. Käibe kasvu TOP 20. Kasumi kasvu TOP 20. Rentaabluse TOP 20. Omakapitali tootlikkuse TOP 20. Võrumaa firmade üld- ja finantsandmed

  13. Võrumaa ettevõtete TOP 50 aastal 2003

    Index Scriptorium Estoniae

    2004-01-01

    Võrumaa ettevõtete TOP 50 aastal 2003. Käibe TOP 40. Kasumi TOP 40. Käibe kasvu TOP 20. Kasumi kasvu TOP 20. Rentaabluse TOP 20. Omakapitali tootlikkuse TOP 20. Võrumaa firmade üld- ja finantsandmed

  14. Australia's Next Top Fraction Model

    Science.gov (United States)

    Gould, Peter

    2013-01-01

    Peter Gould suggests Australia's next top fraction model should be a linear model rather than an area model. He provides a convincing argument and gives examples of ways to introduce a linear model in primary classrooms.

  15. Solar power from Tyrol; Sonne aus Tirol

    Energy Technology Data Exchange (ETDEWEB)

    Berner, J.

    2007-04-03

    A new name, a new production line and many new staff members: Under the new name of Tisun, Tyrol-based producer of solar collectors Teufel and Schwarz intends to become a top producer in the European solar industry. The new central administrative building was commissioned on 16 March 2007. (orig.)

  16. Buckets of Higgs and Tops

    CERN Document Server

    Buckley, Matthew R; Schell, Torben; Takeuchi, Michihisa

    2013-01-01

    We show that associated production of a Higgs with a top pair can be observed in purely hadronic decays. Reconstructing the top quarks in the form of jet buckets allows us to control QCD backgrounds as well as signal combinatorics. The background can be measured from side bands in the reconstructed Higgs mass. We back up our claims with a detailed study of the QCD event simulation, both for the signal and for the backgrounds.

  17. Buckets of Higgs and tops

    Energy Technology Data Exchange (ETDEWEB)

    Buckley, Matthew R. [Center for Particle Astrophysics, Fermi National Accelerator Laboratory,Batavia, IL (United States); Department of Physics and Astronomy, Rutgers University,Piscataway, NJ (United States); Plehn, Tilman; Schell, Torben [Institut für Theoretische Physik, Universität Heidelberg,Heidelberg (Germany); Takeuchi, Michihisa [Theoretical Particle Physics and Cosmology Group, Department of Physics,King’s College London, London WC2R 2LS (United Kingdom)

    2014-02-28

    We show that associated production of a Higgs with a top pair can be observed in purely hadronic decays. Reconstructing the top quarks in the form of jet buckets allows us to control QCD backgrounds as well as signal combinatorics. The background can be measured from side bands in the reconstructed Higgs mass. We back up our claims with a detailed study of the QCD event simulation, both for the signal and for the backgrounds.

  18. Uncovering the single top: observation of electroweak top quark production

    Energy Technology Data Exchange (ETDEWEB)

    Benitez, Jorge Armando [Michigan State Univ., East Lansing, MI (United States)

    2009-01-01

    The top quark is generally produced in quark and anti-quark pairs. However, the Standard Model also predicts the production of only one top quark which is mediated by the electroweak interaction, known as 'Single Top'. Single Top quark production is important because it provides a unique and direct way to measure the CKM matrix element Vtb, and can be used to explore physics possibilities beyond the Standard Model predictions. This dissertation presents the results of the observation of Single Top using 2.3 fb-1 of Data collected with the D0 detector at the Fermilab Tevatron collider. The analysis includes the Single Top muon+jets and electron+jets final states and employs Boosted Decision Tress as a method to separate the signal from the background. The resulting Single Top cross section measurement is: (1) σ(p$\\bar{p}$→ tb + X, tqb + X) = 3.74-0.74+0.95 pb, where the errors include both statistical and systematic uncertainties. The probability to measure a cross section at this value or higher in the absence of signal is p = 1.9 x 10-6. This corresponds to a standard deviation Gaussian equivalence of 4.6. When combining this result with two other analysis methods, the resulting cross section measurement is: (2) σ(p$\\bar{p}$ → tb + X, tqb + X) = 3.94 ± 0.88 pb, and the corresponding measurement significance is 5.0 standard deviations.

  19. Perovskite Solar Cells with Large-Area CVD-Graphene for Tandem Solar Cells.

    Science.gov (United States)

    Lang, Felix; Gluba, Marc A; Albrecht, Steve; Rappich, Jörg; Korte, Lars; Rech, Bernd; Nickel, Norbert H

    2015-07-16

    Perovskite solar cells with transparent contacts may be used to compensate for thermalization losses of silicon solar cells in tandem devices. This offers a way to outreach stagnating efficiencies. However, perovskite top cells in tandem structures require contact layers with high electrical conductivity and optimal transparency. We address this challenge by implementing large-area graphene grown by chemical vapor deposition as a highly transparent electrode in perovskite solar cells, leading to identical charge collection efficiencies. Electrical performance of solar cells with a graphene-based contact reached those of solar cells with standard gold contacts. The optical transmission by far exceeds that of reference devices and amounts to 64.3% below the perovskite band gap. Finally, we demonstrate a four-terminal tandem device combining a high band gap graphene-contacted perovskite top solar cell (Eg = 1.6 eV) with an amorphous/crystalline silicon bottom solar cell (Eg = 1.12 eV).

  20. Development of smart solar tanks

    DEFF Research Database (Denmark)

    Furbo, Simon; Andersen, Elsa

    1999-01-01

    The aim of the project is to develop smart solar tanks. A smart solar tank is a tank in which the domestic water can bee heated both by solar collectors and by an auxiliary energy supply system. The auxiliary energy supply system heats up the hot-water tank from the top and the water volume heated...... by the auxiliary energy supply system is fitted to the hot water consumption and consumption pattern. In periods with a large hot-water demand the volume is large, in periods with a small hot-water demand the volume is small. Based on measurements and calculations the advantage of smart SDHW systems is visualised....

  1. Solar water disinfection (SODIS): A review from bench-top to roof-top

    CSIR Research Space (South Africa)

    McGuigan, KG

    2012-10-01

    Full Text Available it faster and safer. Since SODIS is simple to use and inexpensive, the method has spread throughout the developing world and is in daily use in more than 50 countries in Asia, Latin America, and Africa. More than 5 million people disinfect their drinking...

  2. Solar Features - Solar Flares

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — A solar flare is a short-lived sudden increase in the intensity of radiation emitted in the neighborhood of sunspots. For many years it was best monitored in the...

  3. Solar storms; Tormentas solares

    Energy Technology Data Exchange (ETDEWEB)

    Collaboration: Pereira Cuesta, S.; Pereira Pagan, B.

    2016-08-01

    Solar storms begin with an explosion, or solar flare, on the surface of the sun. The X-rays and extreme ultraviolet radiation from the flare reach the Earths orbit minutes later-travelling at light speed. The ionization of upper layers of our atmosphere could cause radio blackouts and satellite navigation errors (GPS). Soon after, a wave of energetic particles, electrons and protons accelerated by the explosion crosses the orbit of the Earth, and can cause real and significant damage. (Author)

  4. The theory of the top

    CERN Document Server

    Klein, Felix; Nagem, Raymond J; Sandri, Guido

    The Theory of the Top. Volume IV. Technical Applications of the Theory of the Top is the fourth and final volume in a series of self-contained English translations of the classic and definitive treatment of rigid body motion. Key features: * Complete and unabridged presentation with recent advances and additional notes; * Annotations by the translators provide insights into the nature of science and mathematics in the late 19th century; * Each volume interweaves theory and applications. The Theory of the Top was originally presented by Felix Klein as an 1895 lecture at Göttingen University that was broadened in scope and clarified as a result of collaboration with Arnold Sommerfeld.  Graduate students and researchers interested in theoretical and applied mechanics will find this series of books a thorough and insightful account.  Other volumes in the series include Introduction to the Kinematics and Kinetics of the Top, Development of the Theory in the Case of the Heavy Symmetric Top, and Perturbation...

  5. Light 't Hooft Top Partners

    CERN Document Server

    Cacciapaglia, Giacomo

    2015-01-01

    Vector-like quarks, usually dubbed top partners, are a common presence in composite Higgs models. Being composite objects, their mass is expected to be of the order of their inverse size, that is the condensation scale of the new strong interactions. Light top partners, while not being a generic prediction, are however often considered in phenomenological models. We suggest that their lightness may be due to the matching of global 't Hooft anomalies of the underlying theory. We check this mechanism in explicit models showing that, in one case, composite fermions with the quantum numbers of the top quark obtain a mass which is controlled by a soft breaking term and can be made parametrically small.

  6. Observation of the Top Quark

    Science.gov (United States)

    Abachi, S.; Abbott, B.; Abolins, M.; Acharya, B. S.; Adam, I.; Adams, D. L.; Adams, M.; Ahn, S.; Aihara, H.; Alitti, J.; Álvarez, G.; Alves, G. A.; Amidi, E.; Amos, N.; Anderson, E. W.; Aronson, S. H.; Astur, R.; Avery, R. E.; Baden, A.; Balamurali, V.; Balderston, J.; Baldin, B.; Bantly, J.; Bartlett, J. F.; Bazizi, K.; Bendich, J.; Beri, S. B.; Bertram, I.; Bezzubov, V. A.; Bhat, P. C.; Bhatnagar, V.; Bhattacharjee, M.; Bischoff, A.; Biswas, N.; Blazey, G.; Blessing, S.; Boehnlein, A.; Bojko, N. I.; Borcherding, F.; Borders, J.; Boswell, C.; Brandt, A.; Brock, R.; Bross, A.; Buchholz, D.; Burtovoi, V. S.; Butler, J. M.; Casey, D.; Castilla-Valdez, H.; Chakraborty, D.; Chang, S.-M.; Chekulaev, S. V.; Chen, L.-P.; Chen, W.; Chevalier, L.; Chopra, S.; Choudhary, B. C.; Christenson, J. H.; Chung, M.; Claes, D.; Clark, A. R.; Cobau, W. G.; Cochran, J.; Cooper, W. E.; Cretsinger, C.; Cullen-Vidal, D.; Cummings, M.; Cutts, D.; Dahl, O. I.; de, K.; Demarteau, M.; Demina, R.; Denisenko, K.; Denisenko, N.; Denisov, D.; Denisov, S. P.; Dharmaratna, W.; Diehl, H. T.; Diesburg, M.; di Loreto, G.; Dixon, R.; Draper, P.; Drinkard, J.; Ducros, Y.; Dugad, S. R.; Durston-Johnson, S.; Edmunds, D.; Efimov, A. O.; Ellison, J.; Elvira, V. D.; Engelmann, R.; Eno, S.; Eppley, G.; Ermolov, P.; Eroshin, O. V.; Evdokimov, V. N.; Fahey, S.; Fahland, T.; Fatyga, M.; Fatyga, M. K.; Featherly, J.; Feher, S.; Fein, D.; Ferbel, T.; Finocchiaro, G.; Fisk, H. E.; Fisyak, Yu.; Flattum, E.; Forden, G. E.; Fortner, M.; Frame, K. C.; Franzini, P.; Fredriksen, S.; Fuess, S.; Galjaev, A. N.; Gallas, E.; Gao, C. S.; Gao, S.; Geld, T. L.; Genik, R. J., II; Genser, K.; Gerber, C. E.; Gibbard, B.; Glaubman, M.; Glebov, V.; Glenn, S.; Glicenstein, J. F.; Gobbi, B.; Goforth, M.; Goldschmidt, A.; Gomez, B.; Goncharov, P. I.; Gordon, H.; Goss, L. T.; Graf, N.; Grannis, P. D.; Green, D. R.; Green, J.; Greenlee, H.; Griffin, G.; Grossman, N.; Grudberg, P.; Grünendahl, S.; Guida, J. A.; Guida, J. M.; Guryn, W.; Gurzhiev, S. N.; Gutnikov, Y. E.; Hadley, N. J.; Haggerty, H.; Hagopian, S.; Hagopian, V.; Hahn, K. S.; Hall, R. E.; Hansen, S.; Hatcher, R.; Hauptman, J. M.; Hedin, D.; Heinson, A. P.; Heintz, U.; Hernandez-Montoya, R.; Heuring, T.; Hirosky, R.; Hobbs, J. D.; Hoeneisen, B.; Hoftun, J. S.; Hsieh, F.; Hu, Ting; Hu, Tong; Huehn, T.; Igarashi, S.; Ito, A. S.; James, E.; Jaques, J.; Jerger, S. A.; Jiang, J. Z.-Y.; Joffe-Minor, T.; Johari, H.; Johns, K.; Johnson, M.; Johnstad, H.; Jonckheere, A.; Jöstlein, H.; Jun, S. Y.; Jung, C. K.; Kahn, S.; Kang, J. S.; Kehoe, R.; Kelly, M.; Kernan, A.; Kerth, L.; Kim, C. L.; Kim, S. K.; Klatchko, A.; Klima, B.; Klochkov, B. I.; Klopfenstein, C.; Klyukhin, V. I.; Kochetkov, V. I.; Kohli, J. M.; Koltick, D.; Kostritskiy, A. V.; Kotcher, J.; Kourlas, J.; Kozelov, A. V.; Kozlovski, E. A.; Krishnaswamy, M. R.; Krzywdzinski, S.; Kunori, S.; Lami, S.; Landsberg, G.; Lanou, R. E.; Lebrat, J.-F.; Lee-Franzini, J.; Leflat, A.; Li, H.; Li, J.; Li, Y. K.; Li-Demarteau, Q. Z.; Lima, J. G.; Lincoln, D.; Linn, S. L.; Linnemann, J.; Lipton, R.; Liu, Y. C.; Lobkowicz, F.; Loken, S. C.; Lökös, S.; Lueking, L.; Lyon, A. L.; Maciel, A. K.; Madaras, R. J.; Madden, R.; Mandrichenko, I. V.; Mangeot, Ph.; Mani, S.; Mansoulié, B.; Mao, H. S.; Margulies, S.; Markeloff, R.; Markosky, L.; Marshall, T.; Martin, M. I.; Marx, M.; May, B.; Mayorov, A. A.; McCarthy, R.; McKibben, T.; McKinley, J.; Melanson, H. L.; de Mello Neto, J. R.; Merritt, K. W.; Miettinen, H.; Milder, A.; Milner, C.; Mincer, A.; de Miranda, J. M.; Mishra, C. S.; Mohammadi-Baarmand, M.; Mokhov, N.; Mondal, N. K.; Montgomery, H. E.; Mooney, P.; Mudan, M.; Murphy, C.; Murphy, C. T.; Nang, F.; Narain, M.; Narasimham, V. S.; Narayanan, A.; Neal, H. A.; Negret, J. P.; Neis, E.; Nemethy, P.; NešiĆ, D.; Norman, D.; Oesch, L.; Oguri, V.; Oltman, E.; Oshima, N.; Owen, D.; Padley, P.; Pang, M.; Para, A.; Park, C. H.; Park, Y. M.; Partridge, R.; Parua, N.; Paterno, M.; Perkins, J.; Peryshkin, A.; Peters, M.; Piekarz, H.; Pischalnikov, Y.; Pluquet, A.; Podstavkov, V. M.; Pope, B. G.; Prosper, H. B.; Protopopescu, S.; Pušeljić, D.; Qian, J.; Quintas, P. Z.; Raja, R.; Rajagopalan, S.; Ramirez, O.; Rao, M. V.; Rapidis, P. A.; Rasmussen, L.; Read, A. L.; Reucroft, S.; Rijssenbeek, M.; Rockwell, T.; Roe, N. A.; Roldan, J. M.; Rubinov, P.; Ruchti, R.; Rusin, S.; Rutherfoord, J.; Santoro, A.; Sawyer, L.; Schamberger, R. D.; Schellman, H.; Schmid, D.; Sculli, J.; Shabalina, E.; Shaffer, C.; Shankar, H. C.; Shivpuri, R. K.; Shupe, M.; Singh, J. B.; Sirotenko, V.; Smart, W.; Smith, A.; Smith, R. P.; Snihur, R.; Snow, G. R.; Snyder, S.; Solomon, J.; Sood, P. M.; Sosebee, M.; Souza, M.; Spadafora, A. L.; Stephens, R. W.; Stevenson, M. L.; Stewart, D.; Stocker, F.; Stoianova, D. A.; Stoker, D.; Streets, K.; Strovink, M.; Taketani, A.; Tamburello, P.; Tarazi, J.; Tartaglia, M.; Taylor, T. L.; Teiger, J.; Thompson, J.; Trippe, T. G.; Tuts, P. M.; Varelas, N.; Varnes, E. W.; Virador, P. R.; Vititoe, D.; Volkov, A. A.; von Goeler, E.; Vorobiev, A. P.; Wahl, H. D.; Wang, J.; Wang, L. Z.; Warchol, J.; Wayne, M.; Weerts, H.; Wenzel, W. A.; White, A.; White, J. T.; Wightman, J. A.; Wilcox, J.; Willis, S.; Wimpenny, S. J.; Wirjawan, J. V.; Wolf, Z.; Womersley, J.; Won, E.; Wood, D. R.; Xu, H.; Yamada, R.; Yamin, P.; Yanagisawa, C.; Yang, J.; Yasuda, T.; Yoshikawa, C.; Youssef, S.; Yu, J.; Yu, Y.; Zhang, Y.; Zhou, Y. H.; Zhu, Q.; Zhu, Y. S.; Zhu, Z. H.; Zieminska, D.; Zieminski, A.; Zinchenko, A.; Zylberstejn, A.

    1995-04-01

    The D0 Collaboration reports on a search for the standard model top quark in pp¯ collisions at s = 1.8 TeV at the Fermilab Tevatron with an integrated luminosity of approximately 50 pb-1. We have searched for tt¯ production in the dilepton and single-lepton decay channels with and without tagging of b-quark jets. We observed 17 events with an expected background of 3.8+/-0.6 events. The probability for an upward fluctuation of the background to produce the observed signal is 2×10-6 (equivalent to 4.6 standard deviations). The kinematic properties of the excess events are consistent with top quark decay. We conclude that we have observed the top quark and measured its mass to be 199+19-21 (stat) +/-22 (syst) GeV/c2 and its production cross section to be 6.4+/-2.2 pb.

  7. Higher Order Top Squark Decays

    CERN Document Server

    Porod, Werner

    1997-01-01

    Within the Minimal Supersymmetric Standard Model we study the three bod= y decay of the lighter top squark into a b-quark, a W-boson and the lightes= t neutralino and compare this decay with the flavour changing two body deca= y of the lighter top squark into a c-quark and the lightest neutralino. We do = this for scenarios where two body decays at tree level are forbidden for the l= ight top squark. We give the complete analysis for the three body and compare = it with the mentioned two body decay. We discuss our numerical results in vi= ew of the upgraded Tevatron, the LHC and a 500~GeV $e^+ e^-$ Linear Collider.

  8. WordPress Top Plugins

    CERN Document Server

    Corbin, Brandon

    2010-01-01

    Time flies when you're having fun. This is the right way to describe this WordPress Top Plugins book by Brandon Corbin. With real world examples and by showing you the perks of having these plugins installed on your websites, the author is all set to captivate your interest from start to end. Regardless of whether this is your first time working with WordPress, or you're a seasoned WordPress coding ninja, WordPress Top Plugins will walk you through finding and installing the best plugins for generating and sharing content, building communities and reader base, and generating real advertising r

  9. Top pair production at ATLAS

    Directory of Open Access Journals (Sweden)

    Loginov Andrey

    2013-05-01

    Full Text Available An overview of latest ATLAS measurements of top pair (tt̅ production in proton-proton collisions at the LHC at centre-of-mass energies of 7 and 8 TeV is presented. Measurements of the tt̅ production cross section (σtt̅ in various decay channels, including analyses of differential σtt̅ distributions and a study of jet multiplicity in tt̅ production, as well as searches for tt̅ resonances using boosted top techniques and standard methods, are discussed.

  10. Observation of the Top Quark

    Science.gov (United States)

    Kim, S. B.

    1995-08-01

    Top quark production is observed in{bar p}p collisions at{radical}s= 1.8 TeV at the Fermilab Tevatron. The Collider Detector at Fermilab (CDF) and D{O} observe signals consistent with t{bar t} to WWb{bar b}, but inconsistent with the background prediction by 4.8{sigma} (CDF), 4.6a (D{O}). Additional evidence for the top quark Is provided by a peak in the reconstructed mass distribution. The kinematic properties of the excess events are consistent with the top quark decay. They measure the top quark mass to be 176{plus_minus}8(stat.){plus_minus}10(sys.) GeV/c{sup 2} (CDF), 199{sub -21}{sup+19}(stat.){plus_minus}22(sys.) GeV/c{sup 2} (D{O}), and the t{bar t} production cross section to be 6.8{sub -2.4}{sup+3.6}pb (CDF), 6.4{plus_minus}2.2 pb (D{O}).

  11. Top quark mass and kinematics

    Energy Technology Data Exchange (ETDEWEB)

    Barberis, Emanuela; /Northeastern U.

    2006-05-01

    A summary of the results on the measurement of the Top Quark mass and the study of the kinematics of the t{bar t} system at the Tevatron collider is presented here. Results from both the CDF and D0 collaborations are reported.

  12. Suhtekorraldusfirmade TOP 2005 / Triin Raestik

    Index Scriptorium Estoniae

    Raestik, Triin

    2006-01-01

    Suhtekorradusfirmade TOP 8. Vt. samas: Corpore kasvab läbi soovituste ja konkursside; Suhtekorraldajate palkade kasv tõstis PR-teenuse hinda; Euro RSCG laienes Läti ja Leedu turule; Indrek Raudjalg. Personalipuudus toob hinnatõusu; Kristina Seimann. PR-turg seni püsinud stabiilsena; Ettevõtete üldandmed

  13. Internetireklaami TOP 2005 / Triin Raestik

    Index Scriptorium Estoniae

    Raestik, Triin

    2006-01-01

    Internetireklaami TOP 10. Vt. samas: Delfit kasutab üle poole miljoni Eesti elaniku; postimees.ee tahab saada parimaks uudisteportaaliks; Uued reklaamiformaadid osutusid ootamatult populaarseks; epl.ee ootab tuleva aasta lõpuks viiemiljonilist internetikäivet; Ettevõtete üldandmed

  14. Top view of WA3

    CERN Multimedia

    1977-01-01

    The WA3 experiment by the Amsterdam-CERN-Cracow-Munich-Oxford-Rutherford (ACCMORE)Collaboration aimed to study exclusive pion and kaon interactions with protons. WA7 is seen on the backgound (top). The hut on the right is WA3, the hut on the left is WA2.

  15. Top Mass Measurement at CMS

    CERN Document Server

    Duda, Markus

    2006-01-01

    Given the big cross section for \\ttbar production in proton-proton collisions at 14\\TeV, the LHC with its high luminosity will be, among others,a top factory, allowing a precision measurement of the top quark mass. Based on a detailed simulation of the CMS detector, the following top mass reconstruction accuracies are possible in the respective final states with the present knowledge of experimental and theoretical uncertainties. Delta m_t (di-leptonic, 1fbinv) = pm 1.5 (stat) pm 2.9 (syst.) GeVcc Delta m_t (semi-leptonic, 1fbinv) = pm 0.7 (stat) pm 1.9 (syst.) GeVcc Delta m_t (fully hadronic, 1fbinv) = pm 0.6(stat) pm 4.2 (syst.) GeVcc Delta m_t (di-leptonic}, 10 fbinv) = pm 0.5 (stat) pm 1.1 (syst.) GeVcc Delta m_t (semi-leptonic, 10 fbinv) = pm 0.2 (stat) pm 1.1 (syst.) GeVcc Delta m_t (JPsi, 20 fbinv) = pm 1.2 (stat) pm 1.5 (syst.) GeVcc A combined top mass accuracy of mathcal O (1GeVcc) for 10-20fbinv of well-understood CMS data will be feasible.

  16. The Top Theological Degree Producers

    Science.gov (United States)

    Diverse: Issues in Higher Education, 2012

    2012-01-01

    Each year, "Diverse: Issues in Higher Education" publishes a list of the Top 100 producers of associate, bachelor's and graduate degrees awarded to minority students based on research conducted by Dr. Victor M. H. Borden, professor of educational leadership and policy studies at Indiana University Bloomington. This year, for the first…

  17. "Top School Problems" Are Myths.

    Science.gov (United States)

    Males, Mike

    1992-01-01

    A well-known "study" comparing the top school problems of 1940 (talking and gum chewing) with those of 1987 (drug abuse, pregnancy, and violence) is nonexistent. In 1940, 49 percent of all youth did not finish high school, 37,000 teenagers died from violence or disease, and 335,000 teens gave birth. Educators should discount pastoral memories and…

  18. Tree compression with top trees

    DEFF Research Database (Denmark)

    Bille, Philip; Gørtz, Inge Li; Landau, Gad M.;

    2015-01-01

    We introduce a new compression scheme for labeled trees based on top trees. Our compression scheme is the first to simultaneously take advantage of internal repeats in the tree (as opposed to the classical DAG compression that only exploits rooted subtree repeats) while also supporting fast...

  19. Tree compression with top trees

    DEFF Research Database (Denmark)

    Bille, Philip; Gørtz, Inge Li; Landau, Gad M.

    2013-01-01

    We introduce a new compression scheme for labeled trees based on top trees [3]. Our compression scheme is the first to simultaneously take advantage of internal repeats in the tree (as opposed to the classical DAG compression that only exploits rooted subtree repeats) while also supporting fast...

  20. Tree compression with top trees

    DEFF Research Database (Denmark)

    Bille, Philip; Gørtz, Inge Li; Landau, Gad M.

    2015-01-01

    We introduce a new compression scheme for labeled trees based on top trees. Our compression scheme is the first to simultaneously take advantage of internal repeats in the tree (as opposed to the classical DAG compression that only exploits rooted subtree repeats) while also supporting fast...