WorldWideScience

Sample records for high carrier density

  1. Graphene, a material for high temperature devices; intrinsic carrier density, carrier drift velocity, and lattice energy

    CERN Document Server

    Yin, Yan; Wang, Li; Jin, Kuijuan; Wang, Wenzhong

    2016-01-01

    Heat has always been a killing matter for traditional semiconductor machines. The underlining physical reason is that the intrinsic carrier density of a device made from a traditional semiconductor material increases very fast with a rising temperature. Once reaching a temperature, the density surpasses the chemical doping or gating effect, any p-n junction or transistor made from the semiconductor will fail to function. Here, we measure the intrinsic Fermi level (|E_F|=2.93k_B*T) or intrinsic carrier density (n_in=3.87*10^6 cm^-2 K^-2*T^2), carrier drift velocity, and G mode phonon energy of graphene devices and their temperature dependencies up to 2400 K. Our results show intrinsic carrier density of graphene is an order of magnitude less sensitive to temperature than those of Si or Ge, and reveal the great potentials of graphene as a material for high temperature devices. We also observe a linear decline of saturation drift velocity with increasing temperature, and identify the temperature coefficients of ...

  2. High-quality epitaxial graphene devices with low carrier density for resistance metrology

    Science.gov (United States)

    Yang, Yanfei; Huang, Lung-I.; Newell, David; Real, Mariano; Elmquist, Randolph

    2014-03-01

    Epitaxially grown graphene on silicon carbide (SiC) is a promising material for both quantum resistance metrology and wafer-scale electronics. However, monolayers are typically found to be heavily n-doped due to the charge exchange between the graphene and the non-conducting buffer layer beneath that is covalently bonded to the SiC substrate. Carrier densities are usually in the range of 1012 ~ 1013 cm-2, where heavy doping shifts the quantized Hall resistance plateau to high magnetic field values. Various gating methods have been developed to reduce the carrier density, but require lithography processes that increase the probability of contamination that degrades the performance of the devices. Recently, we fabricated high-quality Hall devices on diced semi-insulating SiC wafers, obtaining carrier densities in the range of 1010 ~ 1011 cm-2 and mobility above 104 cm2V-1s-1 without gating. Graphene is grown on the Si face of SiC(0001) substrates and devices are fabricated using a metal layer subtractive process without organic chemical contamination of the graphene. We measure well-developed quantum Hall plateaus with filling factor ν = 2, the fingerprint for monolayer graphene, at magnetic fields below 2 T at liquid helium temperature. A variety of quantum phenomena are observed in these clean, high quality graphene devices. NIST and Georgetown University.

  3. High-density carrier-accumulated and electrically stable oxide thin-film transistors from ion-gel gate dielectric

    Science.gov (United States)

    Fujii, Mami N.; Ishikawa, Yasuaki; Miwa, Kazumoto; Okada, Hiromi; Uraoka, Yukiharu; Ono, Shimpei

    2015-12-01

    The use of indium-gallium-zinc oxide (IGZO) has paved the way for high-resolution uniform displays or integrated circuits with transparent and flexible devices. However, achieving highly reliable devices that use IGZO for low-temperature processes remains a technological challenge. We propose the use of IGZO thin-film transistors (TFTs) with an ionic-liquid gate dielectric in order to achieve high-density carrier-accumulated IGZO TFTs with high reliability, and we discuss a distinctive mechanism for the degradation of this organic-inorganic hybrid device under long-term electrical stress. Our results demonstrated that an ionic liquid or gel gate dielectric provides highly reliable and low-voltage operation with IGZO TFTs. Furthermore, high-density carrier accumulation helps improve the TFT characteristics and reliability, and it is highly relevant to the electronic phase control of oxide materials and the degradation mechanism for organic-inorganic hybrid devices.

  4. Ionic Wind Phenomenon and Charge Carrier Mobility in Very High Density Argon Corona Discharge Plasma

    Science.gov (United States)

    Nur, M.; Bonifaci, N.; Denat, A.

    2014-04-01

    Wind ions phenomenon has been observed in the high density argon corona discharge plasma. Corona discharge plasma was produced by point to plane electrodes and high voltage DC. Light emission from the recombination process was observed visually. The light emission proper follow the electric field lines that occur between point and plane electrodes. By using saturation current, the mobilities of non-thermal electrons and ions have been obtained in argon gas and liquid with variation of density from 2,5 1021 to 2 1022 cm-3. In the case of ions, we found that the behaviour of the apparent mobility inversely proportional to the density or follow the Langevin variation law. For non-thermal electron, mobility decreases and approximately follows a variation of Langevin type until the density <= 0,25 the critical density of argon.

  5. Polaron hopping mediated by nuclear tunnelling in semiconducting polymers at high carrier density

    NARCIS (Netherlands)

    Asadi, Kamal; Kronemeijer, Auke J.; Cramer, Tobias; Koster, L. Jan Anton; Blom, Paul W. M.; de Leeuw, Dago M.

    2013-01-01

    The transition rate for a single hop of a charge carrier in a semiconducting polymer is assumed to be thermally activated. As the temperature approaches absolute zero, the predicted conductivity becomes infinitesimal in contrast to the measured finite conductivity. Here we present a uniform descript

  6. High charge carrier density at the NaTaO3/SrTiO3 hetero-interface

    KAUST Repository

    Nazir, Safdar

    2011-08-05

    The formation of a (quasi) two-dimensional electron gas between the band insulators NaTaO3 and SrTiO3 is studied by means of the full-potential linearized augmented plane-wave method of density functional theory. Optimization of the atomic positions points to only small changes in the chemical bonding at the interface. Both the p-type (NaO)−/(TiO2)0 and n-type (TaO2)+/(SrO)0 interfaces are found to be metallic with high charge carrier densities. The effects of O vacancies are discussed. Spin-polarized calculations point to the formation of isolated O 2pmagnetic moments, located in the metallic region of the p-type interface.

  7. Simultaneous drop in mean free path and carrier density at the pseudogap onset in high-{T}_{{\\rm{c}}} cuprates

    Science.gov (United States)

    Storey, J. G.

    2017-10-01

    High-temperature superconducting cuprates are distinguished by an enigmatic pseudogap which opens near optimal doping where the superconducting transition temperature is highest. Key questions concern its origin and whether it is essential in any way to superconductivity. Recent field-induced normal-state transport experiments on hole-doped cuprates have measured abrupt changes in the doping-dependent Hall number and resistivity, consistent with a drop in carrier density from 1+p to p holes per copper atom, on entering the pseudogap phase. In this work the change in resistivity is analyzed in terms of an antiferromagnetic-order-induced Fermi surface reconstruction model that has already successfully described the Hall number. In order for this model to describe the resistivity we find that the zero-temperature mean free path must also drop abruptly in proportion to the size of the Fermi surface. This suggests that intrapocket scattering underlies the observed upturn in resistivity in the pseudogap state.

  8. Transient saturation absorption spectroscopy excited near the band gap at high excitation carrier density in GaAs

    Institute of Scientific and Technical Information of China (English)

    Wu Song-Jiang; Wang Dan-Ling; Jiang Hong-Bing; Yang Hong; Gong Qi-Huang; Ji Ya-Lin; Lu Wei

    2004-01-01

    @@ Transient saturation absorption spectroscopy in GaAs thin films was investigated using femtosecond pump and supercontinuum probe technique at excitation densities higher than 1× 1019 cm-3. The Coulomb enhancement factor of the electron-hole plasma results in a spectrum hole at the pump wavelength. Two distinct transmission peaks at two sides of the pump wavelength are observed, arising from the bleaching of transitions from the heavy- and light-hole bands to the conduction band. The dynamic process of the transient saturation absorption is fitted using a bi-exponential function. The fast decay process is dominated by the carrier-phonon scattering and the slow process may be attributed to the electron-hole recombination.

  9. High-density lipoprotein as a potential carrier for delivery of a lipophilic antitumoral drug into hepatoma cells

    Institute of Scientific and Technical Information of China (English)

    Bin Lou; Xue-Ling Liao; Man-Ping Wu; Pei-Fang Cheng; Chun-Yan Yin; Zheng Fei

    2005-01-01

    AIM: To investigate the possibility of recombinant highdensity lipoprotein (rHDL) being a carrier for delivering antitumoral drug to hepatoma cells.METHODS: Recombinant complex of HDL and aclacinomycin(rHDL-ACM) was prepared by cosonication of apoproteins from HDL (Apo HDL) and ACM as well as phosphatidylcholine.Characteristics of the rHDL-ACM were elucidated by electrophoretic mobility, including the size of particles,morphology and entrapment efficiency. Binding activity of rHDL-ACM to human hepatoma cells was determined by competition assay in the presence of excess native HDL. The cytotoxicity of rHDL-ACM was assessed by MTT method.RESULTS: The density range of rHDL-ACM was 1.063-1.210g/mL, and the same as that of native HDL. The purity of all rHDL-ACM preparations was more than 92%.Encapsulated efficiencies of rHDL-ACM were more than90%. rHDL-ACM particles were typical sphere model of lipoproteins and heterogeneous in particle size. The average diameter was 31.26±5.62 nm by measure of 110rHDL-ACM particles in the range of diameter of lipoproteins.rHDL-ACM could bind on SMMC-7721 cells, and such binding could be competed against in the presence of excess native HDL. rHDL-ACM had same binding capacity as native HDL. The cellular uptake of rHDL-ACM by SMMC-7721 hepatoma cells was significantly higher than that of free ACM at the concentration range of 0.5-10 μg/mL(P<0.01). Cytotoxicity of rHDL-ACM to SMMC-7721 cells was significantly higher than that of free ACM at concentration range of less than 5 μg/mL (P<0.01) and IC50 of rHDL-ACM was lower than IC50 of free ACM(1.68 nmol/L vs3 nmol/L). Compared to L02 hepatocytes,a normal liver cell line, the cellular uptake of rHDL-ACM by SMMC-7721 cells was significantly higher (P<0.01) and in a dose-dependent manner at the concentration range of 0.5-10 μg/mL. Cytotoxicity of the rHDL-ACM to SMMC-7721 cells was significantly higher than that to L02 cells at concentration range of 1-7.5 μg/mL (P<0.01). IC50 for

  10. Charge-carrier mobilities in disordered semiconducting polymers: effects of carrier density and electric field

    Science.gov (United States)

    Meisel, K. D.; Pasveer, W. F.; Cottaar, J.; Tanase, C.; Coehoorn, R.; Bobbert, P. A.; Blom, P. W. M.; de Leeuw, D. M.; Michels, M. A. J.

    2006-02-01

    We model charge transport in disordered semiconducting polymers by hopping of charge carriers on a square lattice of sites with Gaussian on-site energy disorder, using Fermi-Dirac statistics. From numerically exact solutions of the Master equation, we study the dependence of the charge-carrier mobility on temperature, carrier density, and electric field. Our results are used in calculating current-voltage characteristics of hole-only polymer diodes. It is found that very good fits to experimental current-voltage characteristics can be obtained at different temperatures, with reasonable fitting parameters for the width of the Gaussian density of states and the lattice constant. In agreement with the experiments we find that the density dependence is dominant over the field dependence. Only at high fields and low temperatures the field dependence becomes noticeable. The potential and current distribution show strong inhomogeneities, which may have important consequences for the operation of polymer opto-electronic devices.

  11. Carrier density driven lasing dynamics in ZnO nanowires

    CERN Document Server

    Wille, Marcel; Michalsky, Tom; Röder, Robert; Ronning, Carsten; Schmidt-Grund, Rüdiger; Grundmann, Marius

    2016-01-01

    We report on the temporal lasing dynamics of high quality ZnO nanowires using time-resolved micro-photoluminescence technique. The temperature dependence of the lasing characteristics and of the corresponding decay constants demonstrate the formation of an electron-hole plasma to be the underlying gain mechanism in the considered temperature range from 10 K to 300 K. We found that the temperature dependent emission onset-time ($t_{\\text{on}}$) strongly depends on the excitation power and becomes smallest in the lasing regime, with values below 5 ps. Furthermore, the observed red shift of the dominating lasing modes in time is qualitatively discussed in terms of the carrier density induced change of the refractive index dispersion after the excitation laser pulse. This theory is supported by extending an existing model for the calculation of the carrier density dependent complex refractive index for different temperatures. This model coincides with the experimental observations and reliably describes the evolu...

  12. Manipulation of Carrier Density near Ferroelectric/Semiconductor Interfaces

    Science.gov (United States)

    Kesim, Mehmet; Misirlioglu, I. Burc; Mantese, Joseph; Alpay, S. Pamir

    Switchable polarization of a ferroelectric (FE) opens up the opportunity to control the charge density and transport characteristics at the FE/metal and FE/semiconductor (SC) heterointerfaces. Carrier manipulation near such regions can be used in high density non-volatile memories, switchable diodes, and photovoltaic devices. FEs can be utilized as gate oxides in a metal oxide field-effect transistor configuration for non-volatile memory applications with lower gate voltages compared to that of transistors with linear dielectrics. The channel conductance can be modulated reversibly, for instance, by tuning the magnitude and spatial distribution of polarization in the FE. In this study, we show that FE heterostructures can be used to manipulate the conductivity of a FE/SC interface. We employ a non-linear thermodynamic model based on Landau-Ginzburg-Devonshire (LGD) theory to obtain the equilibrium polarization of heterostructures. The carriers along the heterostructures are mapped through coupling the LGD equation with the Maxwell equations and Fermi - Dirac distribution of charged carriers/ionized dopants in the FE and SC. We consider various configurations including FE/SC/paraelectric and FE/SC/FE stacks to investigate the carrier distribution and band bending near such interfaces. The resulting properties are explained through the phase transition characteristics and domain structure of the stacks.

  13. Charge-carrier mobilities in disordered semiconducting polymers: effects of carrier density and electric field

    Energy Technology Data Exchange (ETDEWEB)

    Meisel, K.D.; Pasveer, W.F.; Cottaar, J.; Bobbert, P.A.; Michels, M.A.J. [Group Polymer Physics, Eindhoven Polymer Laboratories and Dutch Polymer Institute, Technische Universiteit Eindhoven, P.O. Box 513, 5600 MB Eindhoven (Netherlands); Tanase, C.; Blom, P.W.M. [Materials Science Centre and Dutch Polymer Institute, Nijenborgh 4, 9747 AG Groningen (Netherlands); Coehoorn, R.; Leeuw, D.M. de [Philips Research Laboratories, Prof. Holstlaan 4, 5656 AA Eindhoven (Netherlands)

    2006-02-01

    We model charge transport in disordered semiconducting polymers by hopping of charge carriers on a square lattice of sites with Gaussian on-site energy disorder, using Fermi-Dirac statistics. From numerically exact solutions of the Master equation, we study the dependence of the charge-carrier mobility on temperature, carrier density, and electric field. Our results are used in calculating current-voltage characteristics of hole-only polymer diodes. It is found that very good fits to experimental current-voltage characteristics can be obtained at different temperatures, with reasonable fitting parameters for the width of the Gaussian density of states and the lattice constant. In agreement with the experiments we find that the density dependence is dominant over the field dependence. Only at high fields and low temperatures the field dependence becomes noticeable. The potential and current distribution show strong inhomogeneities, which may have important consequences for the operation of polymer opto-electronic devices. (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  14. Coexistence of bulk and surface states probed by Shubnikov-de Haas oscillations in Bi2Se3 with high charge-carrier density

    Science.gov (United States)

    de Vries, E. K.; Pezzini, S.; Meijer, M. J.; Koirala, N.; Salehi, M.; Moon, J.; Oh, S.; Wiedmann, S.; Banerjee, T.

    2017-07-01

    Topological insulators are ideally represented as having an insulating bulk with topologically protected, spin-textured surface states. However, it is increasingly becoming clear that these surface transport channels can be accompanied by a finite conducting bulk, as well as additional topologically trivial surface states. To investigate these parallel conduction transport channels, we studied Shubnikov-de Haas oscillations in Bi2Se3 thin films, in high magnetic fields up to 30 T so as to access channels with a lower mobility. We identify a clear Zeeman-split bulk contribution to the oscillations from a comparison between the charge-carrier densities extracted from the magnetoresistance and the oscillations. Furthermore, our analyses indicate the presence of a two-dimensional state and signatures of additional states the origin of which cannot be conclusively determined. Our findings underpin the necessity of theoretical studies on the origin of and the interplay between these parallel conduction channels for a careful analysis of the material's performance.

  15. Synthetic High-Density Lipoprotein-Like Nanocarrier Improved Cellular Transport of Lysosomal Cholesterol in Human Sterol Carrier Protein-Deficient Fibroblasts.

    Science.gov (United States)

    Nam, Da-Eun; Kim, Ok-Kyung; Park, Yoo Kyoung; Lee, Jeongmin

    2016-01-01

    Sterol carrier protein-2 (SCP-2), which is not found in tissues of people with Zellweger syndrome, facilitates the movement of cholesterol within cells, resulting in abnormal accumulation of cholesterol in SCP-2-deficient cells. This study investigated whether synthetic high-density lipoprotein-like nanocarrier (sHDL-NC) improves the cellular transport of lysosomal cholesterol to plasma membrane in SCP-2-deficient fibroblasts. Human SCP-2-deficient fibroblasts were incubated with [(3)H-cholesterol]LDL as a source of cholesterol and sHDL-NC. The cells were fractionated by centrifugation permit tracking of [(3)H]-cholesterol from lysosome into plasma membrane. Furthermore, cellular content of cholesteryl ester as a storage form and mRNA expression of low-density lipoprotein (LDL) receptor were measured to support the cholesterol transport to plasma membrane. Incubation with sHDL-NC for 8 h significantly increased uptake of [(3)H]-cholesterol to lysosome by 53% and further enhanced the transport of [(3)H]-cholesterol to plasma membrane by 32%. Treatment with sHDL-NC significantly reduced cellular content of cholesteryl ester and increased mRNA expression of LDL receptor (LDL-R). In conclusion, sHDL-NC enables increased transport of lysosomal cholesterol to plasma membrane. In addition, these data were indirectly supported by decreased cellular content of cholesteryl ester and increased gene expression of LDL-R. Therefore, sHDL-NC may be a useful vehicle for transporting cholesterol, which may help to prevent accumulation of cholesterol in SCP-2-deficient fibroblasts.

  16. Carrier density driven lasing dynamics in ZnO nanowires.

    Science.gov (United States)

    Wille, Marcel; Sturm, Chris; Michalsky, Tom; Röder, Robert; Ronning, Carsten; Schmidt-Grund, Rüdiger; Grundmann, Marius

    2016-06-01

    We report on the temporal lasing dynamics of high quality ZnO nanowires using the time-resolved micro-photoluminescence technique. The temperature dependence of the lasing characteristics and of the corresponding decay constants demonstrate the formation of an electron-hole plasma to be the underlying gain mechanism in the considered temperature range from 10 K to 300 K. We found that the temperature-dependent emission onset-time ([Formula: see text]) strongly depends on the excitation power and becomes smallest in the lasing regime, with values below 5 ps. Furthermore, the observed red shift of the dominating lasing modes in time is qualitatively discussed in terms of the carrier density induced change of the refractive index dispersion after the excitation laser pulse. This theory is supported by extending an existing model for the calculation of the carrier density dependent complex refractive index for different temperatures. This model coincides with the experimental observations and reliably describes the evolution of the refractive index after the excitation laser pulse.

  17. Carrier Density and Plasma Frequency of Aluminum Nanofilms

    Institute of Scientific and Technical Information of China (English)

    Hao DU; Jun GONG; Chao SUN; Rongfang HUANG; Lishi WEN; W.Y.Cheung; S.P.Wong

    2003-01-01

    In this work, the prerequisite and mode of electromagnetic response of Al nanofilms to electromagnetic wave field was suggested.Reflectance, transmittance in infrared region and carrier density of the films was measured. With the carrier density of the films, the dependence of their plasma frequencies on the film thickness was obtained. On the other hand, the dependence of absorptance on the frequency of electromagnetic wave field was set up by using the measured reflectance and transmittance,which provided plasma frequency-film thickness relation as well. Similarity of both plasma frequency-film thickness relations proved plasma resonance as a mode of electromagnetic response in Al nanofilms.

  18. Demonstration of the difference Casimir force for samples with different charge carrier densities

    CERN Document Server

    Chen, F; Mohideen, U; Mostepanenko, V M

    2006-01-01

    A measurement of the Casimir force between a gold coated sphere and two Si plates of different carrier densities is performed using a high vacuum based atomic force microscope. The results are compared with the Lifshitz theory and good agreement is found. Our experiment demonstrates that by changing the carrier density of the semiconductor plate by several orders of magnitude it is possible to modify the Casimir interaction. This result may find applications in nanotechnology.

  19. Mobility and carrier density in nanoporous indium tin oxide films

    Energy Technology Data Exchange (ETDEWEB)

    Weissbon, Jaqueline; Gondorf, Andreas; Geller, Martin; Lorke, Axel [Fakultaet fuer Physik and CeNIDE, Universitaet Duisburg-Essen, D-47048 Duisburg (Germany); Inhester, Martina; Prodi-Schwab, Anna; Adam, Dieter [Evonik Degussa GmbH, D-45772 Marl (Germany)

    2011-07-01

    Indium tin oxide (ITO) has become an indispensable material for a range of electronic devices. It is transparent in the entire visible range and electrically conducting, hence, a well suited material for transparent electrodes. An interesting possibility to realize transparent, conducting films without the use of vacuum techniques is the printing of dispersions containing ITO nanoparticles. We study here the charge carrier concentration and mobility of various nanoporous indium tin oxide (ITO) films, using Hall measurements and optical spectroscopy. For the carrier density inside the particles (2-4 . 10{sup 20} cm{sup -3}), the results of these complementary measurement techniques are in good agreement with each other and suggest that even in highly porous materials the common equations for the Hall resistance can be applied. However, for the mobilities in these layers the results differ very strongly: from 50 (cm{sup 2})/(Vs) in optical spectroscopy (which is comparable to bulk ITO) to 0.4 (cm{sup 2})/(Vs) in Hall measurements.This suggests that the mobility for electrical transport in nanoporous ITO films is strongly suppressed by scattering at interparticle boundaries.

  20. Investigating thermal donors in n-type Cz silicon with carrier density imaging

    Directory of Open Access Journals (Sweden)

    Yu Hu

    2012-09-01

    Full Text Available A new method to map the thermal donor concentration in silicon wafers using carrier density imaging is presented. A map of the thermal donor concentration is extracted with high resolution from free carrier density images of a silicon wafer before and after growth of thermal donors. For comparison, free carrier density mapping is also performed using the resistivity method together with linear interpolation. Both methods reveal the same distribution of thermal donors indicating that the carrier density imaging technique can be used to map thermal donor concentration. The interstitial oxygen concentration can also be extracted using the new method in combination with Wijaranakula's model. As part of this work, the lifetime at medium injection level is correlated to the concentration of thermal donors in the as-grown silicon wafer. The recombination rate is found to depend strongly on the thermal donor concentration except in the P-band region.

  1. Charge-carrier relaxation dynamics in highly ordered poly( p -phenylene vinylene): Effects of carrier bimolecular recombination and trapping

    Science.gov (United States)

    Soci, Cesare; Moses, Daniel; Xu, Qing-Hua; Heeger, Alan J.

    2005-12-01

    We have studied the charge-carrier relaxation dynamics in highly ordered poly( p -phenylene vinylene) over a broad time range using fast (t>100ps) transient photoconductivity measurements. The carrier density was also monitored (t>100fs) by means of photoinduced absorption probed at the infrared active vibrational modes. We find that promptly upon charge-carrier photogeneration, the initial polaron dynamics is governed by bimolecular recombination, while later in the subnanosecond time regime carrier trapping gives rise to an exponential decay of the photocurrent. The more sensitive transient photocurrent measurements indicate that in the low excitation regime, when the density of photocarriers is comparable to that of the trapping states (˜1016cm-3) , carrier hopping between traps along with transport via extended states determines the carrier relaxation, a mechanism that is manifested by a long-lived photocurrent “tail.” This photocurrent tail is reduced by lowering the temperature and/or by increasing the excitation density. Based on these data, we develop a comprehensive kinetic model that takes into account the bipolar charge transport, the free-carrier bimolecular recombination, the carrier trapping, and the carrier recombination involving free and trapped carriers.

  2. Charge carrier density in Li-intercalated graphene

    KAUST Repository

    Kaloni, Thaneshwor P.

    2012-05-01

    The electronic structures of bulk C 6Li, Li-intercalated free-standing bilayer graphene, and Li-intercalated bilayer and trilayer graphene on SiC(0 0 0 1) are studied using density functional theory. Our estimate of Young\\'s modulus suggests that Li-intercalation increases the intrinsic stiffness. For decreasing Li-C interaction, the Dirac point shifts to the Fermi level and the associated band splitting vanishes. For Li-intercalated bilayer graphene on SiC(0 0 0 1) the splitting at the Dirac point is tiny. It is also very small at the two Dirac points of Li-intercalated trilayer graphene on SiC(0 0 0 1). For all the systems under study, a large enhancement of the charge carrier density is achieved by Li intercalation. © 2012 Elsevier B.V. All rights reserved.

  3. Ferroelectrically driven spatial carrier density modulation in graphene.

    Science.gov (United States)

    Baeumer, Christoph; Saldana-Greco, Diomedes; Martirez, John Mark P; Rappe, Andrew M; Shim, Moonsub; Martin, Lane W

    2015-01-22

    The next technological leap forward will be enabled by new materials and inventive means of manipulating them. Among the array of candidate materials, graphene has garnered much attention; however, due to the absence of a semiconducting gap, the realization of graphene-based devices often requires complex processing and design. Spatially controlled local potentials, for example, achieved through lithographically defined split-gate configurations, present a possible route to take advantage of this exciting two-dimensional material. Here we demonstrate carrier density modulation in graphene through coupling to an adjacent ferroelectric polarization to create spatially defined potential steps at 180°-domain walls rather than fabrication of local gate electrodes. Periodic arrays of p-i junctions are demonstrated in air (gate tunable to p-n junctions) and density functional theory reveals that the origin of the potential steps is a complex interplay between polarization, chemistry, and defect structures in the graphene/ferroelectric couple.

  4. γ radiation caused graphene defects and increased carrier density

    Institute of Scientific and Technical Information of China (English)

    Han Mai-xing; Ji Zhuo-Yu; Shang Li-Wei; Chen Ying-Ping; Wang Hong; Liu Xin; Li Dong-Mei; Liu Ming

    2011-01-01

    We report on a micro-Raman investigation of inducing defects in mono-layer,bi-layer and tri-layer graphene by γ ray radiation.It is found that the radiation exposure results in two-dimensional(2D)and G band position evolution with the layer number increasing and D and D' bands rising,suggesting the presence of defects and related crystal lattice deformation in graphene.Bi-layer graphene is more stable than mono-and tri-layer graphene,indicating that the former is a better candidate in the application of radiation environments.Also,the DC electrical property of the mono-layer graphene device shows that the defects increase the carrier density.

  5. High Density Matter

    Directory of Open Access Journals (Sweden)

    Stone J.R.

    2013-12-01

    Full Text Available The microscopic composition and properties of matter at super-saturation densities have been the subject of intense investigation for decades. The scarcity of experimental and observational data has led to the necessary reliance on theoretical models. There remains great uncertainty in these models which, of necessity, have to go beyond the over-simple assumption that high density matter consists only of nucleons and leptons. Heavy strange baryons, mesons and quark matter in different forms and phases have to be included to fulfil basic requirements of fundamental laws of physics. In this contribution latest developments in construction of the Equation of State (EoS of high-density matter at zero and finite temperature assuming different composition of matter will be discussed. Critical comparison of model EoS with available experimental data from heavy ion collisions and observations on neutron stars, including gravitational mass, radii and cooling patterns and data on X-ray burst sources and low mass X-ray binaries are made. Fundamental differences between the EoS of low-density, high temperature matter, such as is created in heavy ion collisions and of high-density, low temperature compact objects is discussed.

  6. Contactless Mobility, Carrier Density, and Sheet Resistance Measurements on Si, GaN, and AlGaN/GaN High Electron Mobility Transistor (HEMT) Wafers

    Science.gov (United States)

    2015-02-01

    Si, GaN, and AlGaN/GaN High Electron Mobility Transistor (HEMT) Wafers by Randy P Tompkins and Danh Nguyen Approved for...High Electron Mobility Transistor (HEMT) Wafers by Randy P. Tompkins Sensors and Electron Devices Directorate Danh Nguyen Lehighton...Resistance Measurements on Si, GaN, and AlGaN/GaN High Electron Mobility Transistor (HEMT) Wafers 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM

  7. Charge transport in disordered organic host-guest systems: effects of carrier density and electric field

    Energy Technology Data Exchange (ETDEWEB)

    Yimer, Y Y; Bobbert, P A [Group Polymer Physics, Eindhoven Polymer Laboratories and Dutch Polymer Institute, 5600 MB Eindhoven (Netherlands); Coehoorn, R [Department of Applied Physics, Eindhoven University of Technology, PO Box 513, 5600 MB Eindhoven (Netherlands)], E-mail: Y.Y.Yimer@tue.nl

    2008-08-20

    We investigate charge transport in disordered organic host-guest systems with a bimodal Gaussian density of states (DOS). The energy difference between the two Gaussians defines the trap depth. By solving the Pauli master equation for the hopping of charge carriers on a regular lattice with site energies randomly drawn from the DOS, we obtain the dependence of the charge-carrier mobility on the relative guest concentration, the trap depth, the energetic disorder, the charge-carrier density and the electric field. At small and high guest concentrations, our work provides support for recent semi-analytical model results on the dependence of the mobility on the charge-carrier density at zero field. However, at the cross-over between the trap-limited and trap-to-trap hopping regimes, where the mobility attains a minimum, our results can almost be one order of magnitude larger than predicted semi-analytically. Furthermore, it is shown that field-induced detrapping can contribute strongly to the electric-field dependence of the mobility. A simple analytical expression is provided which describes the effect. This result can be used in continuum drift-diffusion models for charge transport in devices such as organic light-emitting diodes.

  8. Charge transport in disordered organic host guest systems: effects of carrier density and electric field

    Science.gov (United States)

    Yimer, Y. Y.; Bobbert, P. A.; Coehoorn, R.

    2008-08-01

    We investigate charge transport in disordered organic host-guest systems with a bimodal Gaussian density of states (DOS). The energy difference between the two Gaussians defines the trap depth. By solving the Pauli master equation for the hopping of charge carriers on a regular lattice with site energies randomly drawn from the DOS, we obtain the dependence of the charge-carrier mobility on the relative guest concentration, the trap depth, the energetic disorder, the charge-carrier density and the electric field. At small and high guest concentrations, our work provides support for recent semi-analytical model results on the dependence of the mobility on the charge-carrier density at zero field. However, at the cross-over between the trap-limited and trap-to-trap hopping regimes, where the mobility attains a minimum, our results can almost be one order of magnitude larger than predicted semi-analytically. Furthermore, it is shown that field-induced detrapping can contribute strongly to the electric-field dependence of the mobility. A simple analytical expression is provided which describes the effect. This result can be used in continuum drift-diffusion models for charge transport in devices such as organic light-emitting diodes.

  9. Nanoscale Tunable Strong Carrier Density Modulation of 2D Materials for Metamaterials and Other Tunable Optoelectronics

    Science.gov (United States)

    Peng, Cheng; Efetov, Dmitri; Shiue, Ren-Jye; Nanot, Sebastien; Hempel, Marek; Kong, Jing; Koppens, Frank; Englund, Dirk

    Strong spatial tunability of the charge carrier density at nanoscale is essential to many 2D-material-based electronic and optoelectronic applications. As an example, plasmonic metamaterials with nanoscale dimensions would make graphene plasmonics at visible and near-infrared wavelengths possible. However, existing gating techniques based on conventional dielectric gating geometries limit the spatial resolution and achievable carrier concentration, strongly restricting the available wavelength, geometry, and quality of the devices. Here, we present a novel spatially selective electrolyte gating approach that allows for in-plane spatial Fermi energy modulation of 2D materials of more than 1 eV (carrier density of n = 1014 cm-2) across a length of 2 nm. We present electrostatic simulations as well as electronic transport, photocurrent, cyclic voltammetry and optical spectroscopy measurements to characterize the performance of the gating technique applied to graphene devices. The high spatial resolution, high doping capacity, full tunability and self-aligned device geometry of the presented technique opens a new venue for nanoscale metamaterial engineering of 2D materials for complete optical absorption, nonlinear optics and sensing, among other applications.

  10. High Density QCD

    CERN Document Server

    Ducati, M B G

    2001-01-01

    The dynamics of high partonic density QCD is presented considering, in the double logarithm approximation, the parton recombination mechanism built in the AGL formalism, developed including unitarity corrections for the nucleon as well for nucleus. It is shown that these corrections are under theoretical control. The resulting non linear evolution equation is solved in the asymptotic regime, and a comprehensive phenomenology concerning Deep Inelastic Scattering like $F_2$, $F_L$, $F_2^c$. $\\partial F_2/ \\partial \\ln Q^2$, $\\partial F^A_2/ \\partial \\ln Q^2$, etc, is presented. The connection of our formalism with the DGLAP and BFKL dynamics, and with other perturbative (K) and non-perturbative (MV-JKLW) approaches is analised in detail. The phenomena of saturation due to shadowing corrections and the relevance of this effect in ion physics and heavy quark production is emphasized. The implications to e-RHIC, HERA-A, and LHC physics and some open questions are mentioned.

  11. Theory and Simulation of Self- and Mutual-Diffusion of Carrier Density and Temperature in Semiconductor Lasers

    Science.gov (United States)

    Li, Jian-Zhong; Cheung, Samson H.; Ning, C. Z.

    2001-01-01

    Carrier diffusion and thermal conduction play a fundamental role in the operation of high-power, broad-area semiconductor lasers. Restricted geometry, high pumping level and dynamic instability lead to inhomogeneous spatial distribution of plasma density, temperature, as well as light field, due to strong light-matter interaction. Thus, modeling and simulation of such optoelectronic devices rely on detailed descriptions of carrier dynamics and energy transport in the system. A self-consistent description of lasing and heating in large-aperture, inhomogeneous edge- or surface-emitting lasers (VCSELs) require coupled diffusion equations for carrier density and temperature. In this paper, we derive such equations from the Boltzmann transport equation for the carrier distributions. The derived self- and mutual-diffusion coefficients are in general nonlinear functions of carrier density and temperature including many-body interactions. We study the effects of many-body interactions on these coefficients, as well as the nonlinearity of these coefficients for large-area VCSELs. The effects of mutual diffusions on carrier and temperature distributions in gain-guided VCSELs will be also presented.

  12. Lithium-ion-based solid electrolyte tuning of the carrier density in graphene

    OpenAIRE

    Jialin Zhao; Meng Wang; Hui Li; Xuefu Zhang; Lixing You; Shan Qiao; Bo Gao; Xiaoming Xie; Mianheng Jiang

    2016-01-01

    We have developed a technique to tune the carrier density in graphene using a lithium-ion-based solid electrolyte. We demonstrate that the solid electrolyte can be used as both a substrate to support graphene and a back gate. It can induce a change in the carrier density as large as 1 × 1014 cm−2, which is much larger than that induced with oxide-film dielectrics, and it is comparable with that induced by liquid electrolytes. Gate modulation of the carrier density is still visible at 150 K, w...

  13. Lithium-ion-based solid electrolyte tuning of the carrier density in graphene

    Science.gov (United States)

    Zhao, Jialin; Wang, Meng; Li, Hui; Zhang, Xuefu; You, Lixing; Qiao, Shan; Gao, Bo; Xie, Xiaoming; Jiang, Mianheng

    2016-10-01

    We have developed a technique to tune the carrier density in graphene using a lithium-ion-based solid electrolyte. We demonstrate that the solid electrolyte can be used as both a substrate to support graphene and a back gate. It can induce a change in the carrier density as large as 1 × 1014 cm‑2, which is much larger than that induced with oxide-film dielectrics, and it is comparable with that induced by liquid electrolytes. Gate modulation of the carrier density is still visible at 150 K, which is lower than the glass transition temperature of most liquid gating electrolytes.

  14. Lithium-ion-based solid electrolyte tuning of the carrier density in graphene

    Science.gov (United States)

    Zhao, Jialin; Wang, Meng; Li, Hui; Zhang, Xuefu; You, Lixing; Qiao, Shan; Gao, Bo; Xie, Xiaoming; Jiang, Mianheng

    2016-01-01

    We have developed a technique to tune the carrier density in graphene using a lithium-ion-based solid electrolyte. We demonstrate that the solid electrolyte can be used as both a substrate to support graphene and a back gate. It can induce a change in the carrier density as large as 1 × 1014 cm−2, which is much larger than that induced with oxide-film dielectrics, and it is comparable with that induced by liquid electrolytes. Gate modulation of the carrier density is still visible at 150 K, which is lower than the glass transition temperature of most liquid gating electrolytes. PMID:27698413

  15. Controlling Electron-Phonon Interactions in Graphene at Ultrahigh Carrier Densities

    Science.gov (United States)

    Efetov, Dmitri K.; Kim, Philip

    2010-12-01

    We report on the temperature dependent electron transport in graphene at different carrier densities n. Employing an electrolytic gate, we demonstrate that n can be adjusted up to 4×1014cm-2 for both electrons and holes. The measured sample resistivity ρ increases linearly with temperature T in the high temperature limit, indicating that a quasiclassical phonon distribution is responsible for the electron scattering. As T decreases, the resistivity decreases more rapidly following ρ(T)˜T4. This low temperature behavior can be described by a Bloch-Grüneisen model taking into account the quantum distribution of the two-dimensional acoustic phonons in graphene. We map out the density dependence of the characteristic temperature ΘBG defining the crossover between the two distinct regimes, and show that, for all n, ρ(T) scales as a universal function of the normalized temperature T/ΘBG.

  16. Carrier density and lifetime for different dopants in single-crystal and polycrystalline CdTe

    Science.gov (United States)

    Burst, James M.; Farrell, Stuart B.; Albin, David S.; Colegrove, Eric; Reese, Matthew O.; Duenow, Joel N.; Kuciauskas, Darius; Metzger, Wyatt K.

    2016-11-01

    CdTe defect chemistry is adjusted by annealing samples with excess Cd or Te vapor with and without extrinsic dopants. We observe that Group I (Cu and Na) elements can increase hole density above 1016 cm-3, but compromise lifetime and stability. By post-deposition incorporation of a Group V dopant (P) in a Cd-rich ambient, lifetimes of 30 ns with 1016 cm-3 hole density are achieved in single-crystal and polycrystalline CdTe without CdCl2 or Cu. Furthermore, phosphorus doping appears to be thermally stable. This combination of long lifetime, high carrier concentration, and improved stability can help overcome historic barriers for CdTe solar cell development.

  17. Carrier density and lifetime for different dopants in single-crystal and polycrystalline CdTe

    Directory of Open Access Journals (Sweden)

    James M. Burst

    2016-11-01

    Full Text Available CdTe defect chemistry is adjusted by annealing samples with excess Cd or Te vapor with and without extrinsic dopants. We observe that Group I (Cu and Na elements can increase hole density above 1016 cm−3, but compromise lifetime and stability. By post-deposition incorporation of a Group V dopant (P in a Cd-rich ambient, lifetimes of 30 ns with 1016 cm−3 hole density are achieved in single-crystal and polycrystalline CdTe without CdCl2 or Cu. Furthermore, phosphorus doping appears to be thermally stable. This combination of long lifetime, high carrier concentration, and improved stability can help overcome historic barriers for CdTe solar cell development.

  18. High capacity carrier ethernet transport networks

    DEFF Research Database (Denmark)

    Rasmussen, Anders; Zhang, Jiang; Yu, Hao

    2009-01-01

    Ethernet as a transport technology has, up to now, lacked the features such as network layer architecture, customer separation and manageability that carriers require for wide-scale deployment. However, with the advent of PBB-TE and T-MPLS, it is now possible to use Ethernet as a transport...... technology, making the use of Ethernet as a convergence layer for Next Generation Networks a distinct possibility. Triple Play services, in particular IPTV, are expected to be a main drivers for carrier Ethernet, however, a number of challenges must be addressed including QoS enabled control plane, enhanced...... OAM functions, survivability and the increased bandwidth requirements of carrier class systems. This article provides an overview of PBB-TE and T-MPLS and demonstrates how IPTV services can be realized in the framework of Carrier Ethernet. In addition we provide a case study on performing bit error...

  19. High capacity carrier ethernet transport networks

    DEFF Research Database (Denmark)

    Rasmussen, Anders; Zhang, Jiang; Yu, Hao;

    2009-01-01

    Ethernet as a transport technology has, up to now, lacked the features such as network layer architecture, customer separation and manageability that carriers require for wide-scale deployment. However, with the advent of PBB-TE and T-MPLS, it is now possible to use Ethernet as a transport...... technology, making the use of Ethernet as a convergence layer for Next Generation Networks a distinct possibility. Triple Play services, in particular IPTV, are expected to be a main drivers for carrier Ethernet, however, a number of challenges must be addressed including QoS enabled control plane, enhanced...... OAM functions, survivability and the increased bandwidth requirements of carrier class systems. This article provides an overview of PBB-TE and T-MPLS and demonstrates how IPTV services can be realized in the framework of Carrier Ethernet. In addition we provide a case study on performing bit error...

  20. Probability density of tunneled carrier states near heterojunctions calculated numerically by the scattering method.

    Energy Technology Data Exchange (ETDEWEB)

    Wampler, William R.; Myers, Samuel M.; Modine, Normand A.

    2017-09-01

    The energy-dependent probability density of tunneled carrier states for arbitrarily specified longitudinal potential-energy profiles in planar bipolar devices is numerically computed using the scattering method. Results agree accurately with a previous treatment based on solution of the localized eigenvalue problem, where computation times are much greater. These developments enable quantitative treatment of tunneling-assisted recombination in irradiated heterojunction bipolar transistors, where band offsets may enhance the tunneling effect by orders of magnitude. The calculations also reveal the density of non-tunneled carrier states in spatially varying potentials, and thereby test the common approximation of uniform- bulk values for such densities.

  1. High density photovoltaic

    Energy Technology Data Exchange (ETDEWEB)

    Haigh, R.E.; Jacobson, G.F.; Wojtczuk, S. [Spire Corp., Bedford, MA (United States)

    1997-10-14

    Photovoltaic technology can directly generate high voltages in a solid state material through the series interconnect of many photovoltaic diodes. We are investigating the feasibility of developing an electrically isolated, high-voltage power supply using miniature photovoltaic devices that convert optical energy to electrical energy.

  2. Effective mass in bilayer graphene at low carrier densities: The role of potential disorder and electron-electron interaction

    Science.gov (United States)

    Li, J.; Tan, L. Z.; Zou, K.; Stabile, A. A.; Seiwell, D. J.; Watanabe, K.; Taniguchi, T.; Louie, Steven G.; Zhu, J.

    2016-10-01

    In a two-dimensional electron gas, the electron-electron interaction generally becomes stronger at lower carrier densities and renormalizes the Fermi-liquid parameters, such as the effective mass of carriers. We combine experiment and theory to study the effective masses of electrons and holes me* and mh* in bilayer graphene in the low carrier density regime on the order of 1 ×1011c m-2 . Measurements use temperature-dependent low-field Shubnikov-de Haas oscillations observed in high-mobility hexagonal boron nitride supported samples. We find that while me* follows a tight-binding description in the whole density range, mh* starts to drop rapidly below the tight-binding description at a carrier density of n =6 ×1011c m-2 and exhibits a strong suppression of 30% when n reaches 2 ×1011c m-2 . Contributions from the electron-electron interaction alone, evaluated using several different approximations, cannot explain the experimental trend. Instead, the effect of the potential fluctuation and the resulting electron-hole puddles play a crucial role. Calculations including both the electron-electron interaction and disorder effects explain the experimental data qualitatively and quantitatively. This Rapid Communication reveals an unusual disorder effect unique to two-dimensional semimetallic systems.

  3. High Energy Density Capacitors Project

    Data.gov (United States)

    National Aeronautics and Space Administration — NASA?s future space science missions cannot be realized without the state of the art energy storage devices which require high energy density, high reliability, and...

  4. Measuring the mobility of single crystalline wires and its dependence on temperature and carrier density

    Energy Technology Data Exchange (ETDEWEB)

    Amorim, Cleber A; Berengue, Olivia M; Kamimura, Hanay; Chiquito, Adenilson J [NanO LaB-Departamento de Fisica, Universidade Federal de Sao Carlos, CEP 13565-905, CP 676, Sao Carlos, Sao Paulo (Brazil); Leite, Edson R, E-mail: amorim@df.ufscar.br [Laboratorio Interdisciplinar de EletroquImica e Ceramicas, Departamento de Quimica, Universidade Federal de Sao Carlos, CEP 13565-905, CP 676, Sao Carlos, Sao Paulo (Brazil)

    2011-05-25

    Kinetic transport parameters are fundamental for the development of electronic nanodevices. We present new results for the temperature dependence of mobility and carrier density in single crystalline In{sub 2}O{sub 3} samples and the method of extraction of these parameters which can be extended to similar systems. The data were obtained using a conventional Hall geometry and were quantitatively described by the semiconductor transport theory characterizing the electron transport as being controlled by the variable range hopping mechanism. A comprehensive analysis is provided showing the contribution of ionized impurities (low temperatures) and acoustic phonon (high temperatures) scattering mechanisms to the electron mobility. The approach presented here avoids common errors in kinetic parameter extraction from field effect data, serving as a versatile platform for direct investigation of any nanoscale electronic materials.

  5. Influence of carrier density on the electronic cooling channels of bilayer graphene

    NARCIS (Netherlands)

    Limmer, T.; Houtepen, A.J.; Niggebaum, A.; Tautz, R.; Da Como, E.

    2011-01-01

    We study the electronic cooling dynamics in a single flake of bilayer graphene by femtosecond transient absorption probing the photon-energy range 0.25–1.3 eV. From the transients, we extract the carrier cooling curves for different initial temperatures and densities of the photoexcited electrons an

  6. Density-dependent dynamical coexistence of excitons and free carriers in the organolead perovskite C H3N H3Pb I3

    Science.gov (United States)

    Wang, Wei; Li, Yu; Wang, Xiangyuan; Lv, Yanping; Wang, Shufeng; Wang, Kai; Shi, Yantao; Xiao, Lixin; Chen, Zhijian; Gong, Qihuang

    2016-10-01

    The high efficiency of perovskite solar cells benefits from the high density of photoinduced free carriers. We studied how exciton and free carriers, as the two major photoproducts, coexist inside the C H3N H3Pb I3 perovskite. A new density-resolved spectroscopic method was developed for this purpose. The density-dependent coexistence of excitons and free carriers over a wide density range was experimentally observed. The quantitative analysis on the density-resolved spectra revealed a moderate exciton binding energy of 24 ± 2 meV. The results effectively proved that the strong ionic polarization inside the perovskite has a negligible contribution to exciton formation. The spectra also efficiently uncovered the effective mass of electron-hole pairs. Our spectroscopic method and the results profoundly enrich the understanding of the photophysics in perovskite materials for photovoltaic applications.

  7. High Energy Density Laboratory Astrophysics

    CERN Document Server

    Lebedev, Sergey V

    2007-01-01

    During the past decade, research teams around the world have developed astrophysics-relevant research utilizing high energy-density facilities such as intense lasers and z-pinches. Every two years, at the International conference on High Energy Density Laboratory Astrophysics, scientists interested in this emerging field discuss the progress in topics covering: - Stellar evolution, stellar envelopes, opacities, radiation transport - Planetary Interiors, high-pressure EOS, dense plasma atomic physics - Supernovae, gamma-ray bursts, exploding systems, strong shocks, turbulent mixing - Supernova remnants, shock processing, radiative shocks - Astrophysical jets, high-Mach-number flows, magnetized radiative jets, magnetic reconnection - Compact object accretion disks, x-ray photoionized plasmas - Ultrastrong fields, particle acceleration, collisionless shocks. These proceedings cover many of the invited and contributed papers presented at the 6th International Conference on High Energy Density Laboratory Astrophys...

  8. Change of carrier density at the pseudogap critical point of a cuprate superconductor.

    Science.gov (United States)

    Badoux, S; Tabis, W; Laliberté, F; Grissonnanche, G; Vignolle, B; Vignolles, D; Béard, J; Bonn, D A; Hardy, W N; Liang, R; Doiron-Leyraud, N; Taillefer, Louis; Proust, Cyril

    2016-03-10

    The pseudogap is a partial gap in the electronic density of states that opens in the normal (non-superconducting) state of cuprate superconductors and whose origin is a long-standing puzzle. Its connection to the Mott insulator phase at low doping (hole concentration, p) remains ambiguous and its relation to the charge order that reconstructs the Fermi surface at intermediate doping is still unclear. Here we use measurements of the Hall coefficient in magnetic fields up to 88 tesla to show that Fermi-surface reconstruction by charge order in the cuprate YBa2Cu3Oy ends sharply at a critical doping p = 0.16 that is distinctly lower than the pseudogap critical point p* = 0.19 (ref. 11). This shows that the pseudogap and charge order are separate phenomena. We find that the change in carrier density n from n = 1 + p in the conventional metal at high doping (ref. 12) to n = p at low doping (ref. 13) starts at the pseudogap critical point. This shows that the pseudogap and the antiferromagnetic Mott insulator are linked.

  9. Saturation and High Density QCD

    OpenAIRE

    Mueller, A. H.

    2005-01-01

    Recent progress in understanding general properties of high energy scattering near the unitarity limit, where high density gluon components of the wavefunction are dominant, is reviewed. The similarity of the QCD problem and that of reaction-diffusion processes in statistical physics is emphasized. The energy dependence of the saturation momentum and the status of geometric scaling are discussed.

  10. High-density multicore fibers

    DEFF Research Database (Denmark)

    Takenaga, K.; Matsuo, S.; Saitoh, K.;

    2016-01-01

    High-density single-mode multicore fibers were designed and fabricated. A heterogeneous 30-core fiber realized a low crosstalk of −55 dB. A quasi-single-mode homogeneous 31-core fiber attained the highest core count as a single-mode multicore fiber....

  11. High density matter at RHIC

    Indian Academy of Sciences (India)

    Thomas S Ullrich

    2004-02-01

    QCD predicts a phase transition between hadronic matter and a quark-gluon plasma at high energy density. The relativistic heavy ion collider (RHIC) at Brookhaven National Laboratory is a new facility dedicated to the experimental study of matter under extreme conditions. Already the first round of experimental results at RHIC indicated that the conditions to create a new state of matter are indeed reached in the collisions of heavy nuclei. Studies of particle spectra and their correlations at low transverse momenta provide evidence of strong pressure gradients in the highly interacting dense medium and hint that we observe a system in thermal equilibrium. Recent runs with high statistics allow us to explore the regime of hard-scattering processes where the suppression of hadrons at large transverse momentum, and quenching of di-jets are observed thus providing further evidence for extreme high density matter created in collisions at RHIC.

  12. Charge carrier density dependence of the hole mobility in poly(p-phenylene vinylene)

    OpenAIRE

    Tanase, C; Blom, PWM; De Leeuw, DM; de Meijer, EJ

    2004-01-01

    The hole transport in various poly(p-phenylene vinylene) (PPV) derivatives has been investigated in field-effect transistors (FETs) and light-emitting diodes (LEDs) as a function of temperature and applied bias. The discrepancy between the experimental hole mobilities extracted from FETs and LEDs based on a single disordered polymeric semiconductor originates from the strong dependence of the hole mobility on the charge carrier density. The microscopic charge transport parameters are directly...

  13. Determination of charge carrier mobility in doped low density polyethylene using DC transients

    DEFF Research Database (Denmark)

    Khalil, M.Salah; Henk, Peter O; Henriksen, Mogens

    1989-01-01

    Charge carrier mobility was determined for plain and doped low-density polyethylene (LDPE) using DC transient currents. Barium titanate was used as a strongly polar dopant and titanium dioxide as a semiconductor dopant. The values of the mobility obtained were on the order of 10-10 cm2 v-1 s-1...... by a factor of five. Charge trapping and space charge formation were modified by the introduction of titanium dioxide...

  14. High density fluoride glass calorimeter

    Science.gov (United States)

    Xie, Q.; Scheltzbaum, J.; Akgun, U.

    2014-04-01

    The unprecedented radiation levels in current Large Hadron Collider runs, and plans to even increase the luminosity creates a need for new detector technologies to be investigated. Quartz plates to replace the plastic scintillators in current LHC calorimeters have been proposed in recent reports. Quartz based Cherenkov calorimeters can solve the radiation damage problem, however light production and transfer have proven to be challenging. This report summarizes the results from a computational study on the performance of a high-density glass calorimeter. High-density, scintillating, fluoride glass, CHG3, was used as the active material. This glass has been developed specifically for hadron collider experiments, and is known for fast response time, in addition to high light yield. Here, the details of a Geant4 model for a sampling calorimeter prototype with 20 layers, and its hadronic as well as electromagnetic performances are reported.

  15. Dynamics of Below-Band-Gap Carrier in Highly Excited GaN

    Institute of Scientific and Technical Information of China (English)

    郭冰; 黄锦圣; 叶志镇; 江红星; 林景瑜

    2003-01-01

    Femtosecond time-resolved reflectivity was used to investigate below-band-gap (3.1 eV) carrier dynamics in a nominally undoped GaN epilayer under high excitation. A 2.5-ps rising process can be observed in the transient trace. This shot rising time results from the hot phonon effects which can cause a delayed energy relaxation of the initial photocarriers toward the band edge. From the density dependence of the carrier dynamics, the Mott density was estimated to be 1.51-1.56 × 1019 cm-3. Below the Mott density, the initial probed carrier dynamics was explained to the effect of acoustic phonon-assisted tunnelling for localized states, where a significant excitation density dependence of the tunnelling probability was observed due to the optically induced bandtail extension to lower energies. Above the Mott density, the measured carrier dynamics reflected the relaxation of an electron-hole plasma, in which a distinct fast decay component of 2.3 ps was observed due to the onset of nonlinear relaxation processes such Auger recombination.

  16. Thickness dependent charge transfer states and dark carriers density in vacuum deposited small molecule organic photocell

    Science.gov (United States)

    Shekhar, Himanshu; Tzabari, Lior; Solomeshch, Olga; Tessler, Nir

    2016-10-01

    We have investigated the influence of the active layer thickness on the balance of the internal mechanisms affecting the efficiency of copper phthalocyanine - fullerene (C60) based vacuum deposited bulk heterojunction organic photocell. We fabricated a range of devices for which we varied the thickness of the active layer from 40 to 120 nm and assessed their performance using optical and electrical characterization techniques. As reported previously for phthalocyanine:C60, the performance of the device is highly dependent on the active layer thickness and of all the thicknesses we tried, the 40 nm thin active layer device showed the best solar cell characteristic parameters. Using the transfer matrix based optical model, which includes interference effects, we calculated the optical power absorbed in the active layers for the entire absorption band, and we found that this cannot explain the trend with thickness. Measurement of the cell quantum efficiency as a function of light intensity showed that the relative weight of the device internal processes changes when going from 40 nm to 120 nm thick active layer. Electrical modeling of the device, which takes different internal processes into account, allowed to quantify the changes in the processes affecting the generation - recombination balance. Sub gap external quantum efficiency and morphological analysis of the surface of the films agree with the model's result. We found that as the thickness grows the density of charge transfer states and of dark carriers goes up and the uniformity in the vertical direction is reduced.

  17. High energy density aluminum battery

    Energy Technology Data Exchange (ETDEWEB)

    Brown, Gilbert M.; Paranthaman, Mariappan Parans; Dai, Sheng; Dudney, Nancy J.; Manthiram, Arumugan; McIntyre, Timothy J.; Sun, Xiao-Guang; Liu, Hansan

    2016-10-11

    Compositions and methods of making are provided for a high energy density aluminum battery. The battery comprises an anode comprising aluminum metal. The battery further comprises a cathode comprising a material capable of intercalating aluminum or lithium ions during a discharge cycle and deintercalating the aluminum or lithium ions during a charge cycle. The battery further comprises an electrolyte capable of supporting reversible deposition and stripping of aluminum at the anode, and reversible intercalation and deintercalation of aluminum or lithium at the cathode.

  18. High energy density aluminum battery

    Science.gov (United States)

    Brown, Gilbert M.; Paranthaman, Mariappan Parans; Dai, Sheng; Dudney, Nancy J.; Manthiram, Arumugan; McIntyre, Timothy J.; Sun, Xiao-Guang; Liu, Hansan

    2016-10-11

    Compositions and methods of making are provided for a high energy density aluminum battery. The battery comprises an anode comprising aluminum metal. The battery further comprises a cathode comprising a material capable of intercalating aluminum or lithium ions during a discharge cycle and deintercalating the aluminum or lithium ions during a charge cycle. The battery further comprises an electrolyte capable of supporting reversible deposition and stripping of aluminum at the anode, and reversible intercalation and deintercalation of aluminum or lithium at the cathode.

  19. Structure, ionic conductivity and mobile carrier density in fast ionic conducting chalcogenide glasses

    Energy Technology Data Exchange (ETDEWEB)

    Yao, Wenlong [Iowa State Univ., Ames, IA (United States)

    2006-01-01

    This thesis consists of six sections. The first section gives the basic research background on the ionic conduction mechanism in glass, polarization in the glass, and the method of determining the mobile carrier density in glass. The proposed work is also included in this section. The second section is a paper that characterizes the structure of MI + M2S + (0.1 Ga2S3 + 0.9 GeS2) (M = Li, Na, K and Cs) glasses using Raman and IR spectroscopy. Since the ionic radius plays an important role in determining the ionic conductivity in glasses, the glass forming range for the addition of different alkalis into the basic glass forming system 0.1 Ga2S3 + 0.9 GeS2 was studied. The study found that the change of the alkali radius for the same nominal composition causes significant structure change to the glasses. The third section is a paper that investigates the ionic conductivity of MI + M2S + (0.1Ga2S3 + 0.9 GeS2) (M = Li, Na, K and Cs) glasses system. Corresponding to the compositional changes in these fast ionic conducting glasses, the ionic conductivity shows changes due to the induced structural changes. The ionic radius effect on the ionic conductivity in these glasses was investigated. The fourth section is a paper that examines the mobile carrier density based upon the measurements of space charge polarization. For the first time, the charge carrier number density in fast ionic conducting chalcogenide glasses was determined. The experimental impedance data were fitted using equivalent circuits and the obtained parameters were used to determine the mobile carrier density. The influence of mobile carrier density and mobility on the ionic conductivity was separated. The fifth section is a paper that studies the structures of low-alkali-content Na2S + B2S3 (x ≤ 0.2) glasses by neutron and synchrotron x-ray diffraction

  20. Highly efficient carrier multiplication in PbS nanosheets

    NARCIS (Netherlands)

    Aerts, M.; Bielewicz, T.; Klinke, C.; Grozema, F.C.; Houtepen, A.J.; Schins, J.M.; Siebbeles, L.D.A.

    2014-01-01

    Semiconductor nanocrystals are promising for use in cheap and highly efficient solar cells. A high efficiency can be achieved by carrier multiplication (CM), which yields multiple electron-hole pairs for a single absorbed photon. Lead chalcogenide nanocrystals are of specific interest, since their b

  1. High power terahertz induced carrier multiplication in Silicon

    DEFF Research Database (Denmark)

    Tarekegne, Abebe Tilahun; Pedersen, Pernille Klarskov; Iwaszczuk, Krzysztof;

    2015-01-01

    The application of an intense THz field results a nonlinear transmission in high resistivity silicon. Upon increasing field strength, the transmission falls from 70% to 62% due to carrier generation through THz-induced impact ionization and subsequent absorption of the THz field by free electrons....

  2. Low trap-state density and long carrier diffusion in organolead trihalide perovskite single crystals

    KAUST Repository

    Shi, Dong

    2015-01-29

    The fundamental properties and ultimate performance limits of organolead trihalide MAPbX3(MA = CH3NH3 +; X = Br- or I- ) perovskites remain obscured by extensive disorder in polycrystalline MAPbX3 films. We report an antisolvent vapor-assisted crystallization approach that enables us to create sizable crack-free MAPbX3 single crystals with volumes exceeding 100 cubic millimeters. These large single crystals enabled a detailed characterization of their optical and charge transport characteristics.We observed exceptionally low trap-state densities on the order of 109 to 1010 per cubic centimeter in MAPbX3 single crystals (comparable to the best photovoltaic-quality silicon) and charge carrier diffusion lengths exceeding 10 micrometers. These results were validated with density functional theory calculations.

  3. Enhanced carrier density in Nb-doped SrTiO3 thermoelectrics

    KAUST Repository

    Ozdogan, K.

    2012-03-08

    We study epitaxial SrTiO3 interfaced with Nb-doped SrTi1-x Nb x O3 (x = 0, 0.125, 0.25, 0.375, and 0.5) by full-potential density functional theory. From the electronic band structures obtained by our ab-initio calculations we determine the dependence of the induced metallicity on the Nb concentration. We obtain a monotonous increase of the carrier density with the Nb concentration. The results are confirmed by experiments for SrTi0.88Nb0.12O3 and SrTi0.8Nb0.2O3, demonstrating the predictive power and limitations of our theoretical approach. We also show that the Seebeck coefficient decreases monotonously with increasing temperature.

  4. High carrier frequency of 21-hydroxylase deficiency in Cyprus.

    Science.gov (United States)

    Phedonos, A A P; Shammas, C; Skordis, N; Kyriakides, T C; Neocleous, V; Phylactou, L A

    2013-12-01

    Congenital adrenal hyperplasia (CAH) due to 21-hydroxylase deficiency (21-OHD) is a common autosomal recessive disorder caused by mutations in the CYP21A2 gene. The carrier frequency of CYP21A2 mutations has been estimated to be 1:25 to 1:10 on the basis of newborn screening. The main objective of this study was to determine the carrier frequency in the Cypriot population of mutations in the CYP21A2 gene. Three hundred unrelated subjects (150 males and 150 females) from the general population of Cyprus were screened for mutations in the CYP21A2 gene and its promoter. The CYP21A2 genotype analysis identified six different mutants and revealed a carrier frequency of 9.83% with the mild p.Val281Leu being the most frequent (4.3%), followed by p.Qln318stop (2.5%), p.Pro453Ser (1.33%), p.Val304Met (0.83%), p.Pro482Ser (0.67%) and p.Met283Val (0.17%). The notable high CYP21A2 carrier frequency of the Cypriot population is one of the highest reported so far by genotype analysis. Knowledge of the mutational spectrum of CYP21A2 will enable to optimize mutation detection strategy for genetic diagnosis of 21-OHD not only in Cyprus, but also the greater Mediterranean region.

  5. Carrier-Density-Dependent Electron Spin Relaxation in GaAs/AlGaAs Multi Quantum Wells

    Institute of Scientific and Technical Information of China (English)

    SHOU Qian; WU Yu; LIU Lu-Ning; WEN Jin-Hui; LAI Tian-Shu; LIN Wei-Zhu

    2005-01-01

    @@ The carrier-density-dependent electron spin relaxation processes in GaAs/AlGaAs multi quantum wells are investigated by a femtosecond pump probe experiment. The spin relaxation time presents two distinguishable trends with the increasing excitation density. It increases from 60ps to 70ps with carrier densities from 1 × 1017 cm-3to 5 × 1017 cm-3 and gradually saturates up to ~80ps at 4 × 1018 cm-3. The experimental results are attributed to the combined competition between collision intensification and scattering potential screening and provide a good experimental confirmation for the theoretical D'yakonov-Perel' mechanism descriptions.

  6. Density limits investigation and high density operation in EAST tokamak

    Science.gov (United States)

    Zheng, Xingwei; Li, Jiangang; Hu, Jiansheng; Liu, Haiqing; Jie, Yinxian; Wang, Shouxin; Li, Jiahong; Duan, Yanming; Li, Miaohui; Li, Yongchun; Zhang, Ling; Ye, Yang; Yang, Qingquan; Zhang, Tao; Cheng, Yingjie; Xu, Jichan; Wang, Liang; Xu, Liqing; Zhao, Hailin; Wang, Fudi; Lin, Shiyao; Wu, Bin; Lyu, Bo; Xu, Guosheng; Gao, Xiang; Shi, Tonghui; He, Kaiyang; Lan, Heng; Chu, Nan; Cao, Bin; Sun, Zhen; Zuo, Guizhong; Ren, Jun; Zhuang, Huidong; Li, Changzheng; Yuan, Xiaolin; Yu, Yaowei; Wang, Houyin; Chen, Yue; Wu, Jinhua; EAST Team

    2016-05-01

    Increasing the density in a tokamak is limited by the so-called density limit, which is generally performed as an appearance of disruption causing loss of plasma confinement, or a degradation of high confinement mode which could further lead to a H  →  L transition. The L-mode and H-mode density limit has been investigated in EAST tokamak. Experimental results suggest that density limits could be triggered by either edge cooling or excessive central radiation. The L-mode density limit disruption is generally triggered by edge cooling, which leads to the current profile shrinkage and then destabilizes a 2/1 tearing mode, ultimately resulting in a disruption. The L-mode density limit scaling agrees well with the Greenwald limit in EAST. The observed H-mode density limit in EAST is an operational-space limit with a value of 0.8∼ 0.9{{n}\\text{GW}} . High density H-mode heated by neutral beam injection (NBI) and lower hybrid current drive (LHCD) are analyzed, respectively. The constancy of the edge density gradients in H-mode indicates a critical limit caused perhaps by e.g. ballooning induced transport. The maximum density is accessed at the H  →  L transition which is generally caused by the excessive core radiation due to high Z impurities (Fe, Cu). Operating at a high density (>2.8× {{10}19} {{\\text{m}}-3} ) is favorable for suppressing the beam shine through NBI. High density H-mode up to 5.3× {{10}19}{{\\text{m}}-3}~≤ft(∼ 0.8{{n}\\text{GW}}\\right) could be sustained by 2 MW 4.6 GHz LHCD alone, and its current drive efficiency is studied. Statistics show that good control of impurities and recycling facilitate high density operation. With careful control of these factors, high density up to 0.93{{n}\\text{GW}} stable H-mode operation was carried out heated by 1.7 MW LHCD and 1.9 MW ion cyclotron resonance heating with supersonic molecular beam injection fueling.

  7. First measurements of charge carrier density and mobility of in-situ enriched 28Si

    Science.gov (United States)

    Ramanayaka, A. N.; Dwyer, K. J.; Kim, Hyun-Soo; Stewart, M. D., Jr.; Pomeroy, J. M.

    Magnetotransport in top gated Hall bar devices is investigated to characterize the electrical properties of in-situ enriched 28Si. Isotopically enriched 28Si is an ideal candidate for quantum information processing devices as the elimination of unpaired nuclear spins improves the fidelity of the quantum information. Using mass filtered ion beam deposition we, in-situ, enrich and deposit epitaxial 28Si, achieving several orders of magnitude better enrichment compared to other techniques. In order to explore the electrical properties and optimize the growth conditions of in-situ enriched 28Si we perform magnetotransport measurements on top gated Hall bar devices at temperatures ranging from 300 K to cryogenic temperatures and at moderate magnetic fields. Here, we report on the charge carrier density and mobility extracted from such experiments, and will be compared among different growth conditions of in-situ enriched 28Si.

  8. Carrier density dependence of plasmon-enhanced nonradiative energy transfer in a hybrid quantum well-quantum dot structure.

    Science.gov (United States)

    Higgins, L J; Karanikolas, V D; Marocico, C A; Bell, A P; Sadler, T C; Parbrook, P J; Bradley, A L

    2015-01-26

    An array of Ag nanoboxes fabricated by helium-ion lithography is used to demonstrate plasmon-enhanced nonradiative energy transfer in a hybrid quantum well-quantum dot structure. The nonradiative energy transfer, from an InGaN/GaN quantum well to CdSe/ZnS nanocrystal quantum dots embedded in an ~80 nm layer of PMMA, is investigated over a range of carrier densities within the quantum well. The plasmon-enhanced energy transfer efficiency is found to be independent of the carrier density, with an efficiency of 25% reported. The dependence on carrier density is observed to be the same as for conventional nonradiative energy transfer. The plasmon-coupled energy transfer enhances the QD emission by 58%. However, due to photoluminescence quenching effects an overall increase in the QD emission of 16% is observed.

  9. Magnetotransport of the low-carrier density one-dimensional =1/2 antiferromagnet Yb4As3

    Indian Academy of Sciences (India)

    P Gegenwart; H Aoki; T Cichorek; J Custers; M Jaime; A Ochiai; F Steglich

    2002-05-01

    The transport properties of the semimetallic quasi-one-dimensional = 1/2 antiferromagnet Yb4As3 have been studied by performing low-temperature ( ≥ 0.02 K) and high magnetic-field ( ≤ 60 T) measurements of the electrical resistivity ρ(, ). For ≳ 2 K a `heavy-fermion’-like behavior ρ() = 2 with huge and nearly field-independent coefficient ≈ 3 cm/K2 is observed, whereas at lower temperatures ρ() deviates from this behavior and slightly increases to the lowest . In > 0 and ≲ 6 K the resistivity shows an anomalous magnetic-history dependence together with an unusual relaxation behavior. In the isothermal resistivity Shubnikov–de Haas (SdH) oscillations, arising from a low-density system of mobile As-4 holes, with a frequency of 25 T have been recorded. From the - and -dependence of the SdH oscillations an effective carrier mass of (0.275 ± 0.005) 0 and a charge-carrier mean-free path of 215 Å are determined. Furthermore, in ≥ 15 T, the system is near the quantum limit and spin-splitting effects are observed.

  10. High-density lipoprotein cholesterol: How High

    Directory of Open Access Journals (Sweden)

    G Rajagopal

    2012-01-01

    Full Text Available The high-density lipoprotein cholesterol (HDL-C is considered anti-atherogenic good cholesterol. It is involved in reverse transport of lipids. Epidemiological studies have found inverse relationship of HDL-C and coronary heart disease (CHD risk. When grouped according to HDL-C, subjects having HDL-C more than 60 mg/dL had lesser risk of CHD than those having HDL-C of 40-60 mg/dL, who in turn had lesser risk than those who had HDL-C less than 40 mg/dL. No upper limit for beneficial effect of HDL-C on CHD risk has been identified. The goals of treating patients with low HDL-C have not been firmly established. Though many drugs are known to improve HDL-C concentration, statins are proven to improve CHD risk and mortality. Cholesteryl ester transfer protein (CETP is involved in metabolism of HDL-C and its inhibitors are actively being screened for clinical utility. However, final answer is still awaited on CETP-inhibitors.

  11. Effective suppression of efficiency droop in GaN-based light-emitting diodes: role of significant reduction of carrier density and built-in field

    Science.gov (United States)

    Yoo, Yang-Seok; Na, Jong-Ho; Son, Sung Jin; Cho, Yong-Hoon

    2016-01-01

    A critical issue in GaN-based high power light-emitting diodes (LEDs) is how to suppress the efficiency droop problem occurred at high current injection while improving overall quantum efficiency, especially in conventional c-plane InGaN/GaN quantum well (QW), without using complicated bandgap engineering or unconventional materials and structures. Although increasing thickness of each QW may decrease carrier density in QWs, formation of additional strain and defects as well as increased built-in field effect due to enlarged QW thickness are unavoidable. Here, we propose a facile and effective method for not only reducing efficiency droop but also improving quantum efficiency by utilizing c-plane InGaN/GaN QWs having thinner barriers and increased QW number while keeping the same single well thickness and total active layer thickness. As the barrier thickness decreases and the QW number increases, both internal electric field and carrier density within QWs are simultaneously reduced without degradation of material quality. Furthermore, we found overall improved efficiency and reduced efficiency droop, which was attributed to the decrease of the built-in field and to less influence by non-radiative recombination processes at high carrier density. This simple and effective approach can be extended further for high power ultraviolet, green, and red LEDs. PMID:27756916

  12. Dynamical co-existence of excitons and free carriers in perovskite probed by density-resolved fluorescent spectroscopic method

    CERN Document Server

    Wang, Wei; Wang, Xiangyuan; Lv, Yanping; Wang, Shufeng; Wang, Kai; Shi, Yantao; Xiao, Lixin; Chen, Zhijian; Gong, Qihuang

    2016-01-01

    Using transient fluorescent spectra at time-zero, we develop a density-resolved fluorescent spectroscopic method for investigating photoproducts in CH3NH3PbI3 perovskite and related photophysics. The density dependent dynamical co-existence of excitons and free carriers over a wide density range is experimentally observed for the first time. The exciton binding energy (EB) and the effective mass of electron-hole pair can be estimated based on such co-existence. No ionic polarization is found contributing to photophysical behavior. It also solves the conflict between the large experimentally measured EB and the small predicted values. The spectroscopic method also helps to detect the true free carrier density under continuous illumination without the interference of ionic conductivity. Our methods and results profoundly enrich the study and understanding of the photophysics in perovskite materials for photovoltaic applications.

  13. Effect of doping- and field-induced charge carrier density on the electron transport in nanocrystalline ZnO.

    Science.gov (United States)

    Hammer, Maria S; Rauh, Daniel; Lorrmann, Volker; Deibel, Carsten; Dyakonov, Vladimir

    2008-12-03

    The charge transport properties of thin films of sol-gel processed undoped and Al-doped zinc oxide nanoparticles with variable doping level between 0.8 and 10 at.% were investigated. The x-ray diffraction studies revealed a decrease of the average crystallite sizes in highly doped samples. We provide estimates of the conductivity and the resulting charge carrier densities with respect to the doping level. The increase of charge carrier density due to extrinsic doping was compared to the accumulation of charge carriers in field effect transistor structures. This allowed us to assess the scattering effects due to extrinsic doping on the electron mobility. The latter decreases from 4.6 × 10(-3) to 4.5 × 10(-4) cm(2) V(-1) s(-1) with increasing doping density. In contrast, the accumulation leads to an increasing mobility up to 1.5 × 10(-2) cm(2) V(-1) s(-1). The potential barrier heights related to grain boundaries between the crystallites were derived from temperature dependent mobility measurements. The extrinsic doping initially leads to a grain boundary barrier height lowering, followed by an increase due to doping-induced structural defects. We conclude that the conductivity of sol-gel processed nanocrystalline ZnO:Al is governed by an interplay of the enhanced charge carrier density and the doping-induced charge carrier scattering effects, achieving a maximum at 0.8 at.% in our case.

  14. Mapping Charge Carrier Density in Organic Thin-Film Transistors by Time-Resolved Photoluminescence Lifetime Studies

    DEFF Research Database (Denmark)

    Leißner, Till; Jensen, Per Baunegaard With; Liu, Yiming

    2017-01-01

    /organic interface or at grain boundaries. In our comprehensive experimental and analytical work we demonstrate a method to characterize the charge carrier density in organic thin-film transistors using time-resolved photoluminescence spectroscopy. We developed a numerical model that describes the electrical...

  15. Superconductivity in transparent zinc-doped In2O3 films having low carrier density

    Directory of Open Access Journals (Sweden)

    Kazumasa Makise, Nobuhito Kokubo, Satoshi Takada, Takashi Yamaguti, Syunsuke Ogura, Kazumasa Yamada, Bunjyu Shinozaki, Koki Yano, Kazuyoshi Inoue and Hiroaki Nakamura

    2008-01-01

    Full Text Available Thin polycrystalline zinc-doped indium oxide (In2O3–ZnO films were prepared by post-annealing amorphous films with various weight concentrations x of ZnO in the range 0≤x ≤0.06. We have studied the dependences of the resistivity ρ and Hall coefficient on temperature T and magnetic field H in the range 0.5≤T ≤300 K, H≤6 Tfor 350 nm films annealed in air. Films with 0≤x≤0.03 show the superconducting resistive transition. The transition temperature Tc is below 3.3 K and the carrier density n is about 1025–1026 m−3. The annealed In2O3–ZnO films were examined by transmission electron microscopy and x-ray diffraction analysis revealing that the crystallinity of the films depends on the annealing time. We studied the upper critical magnetic field Hc2 (T for the film with x = 0.01. From the slope of dHc2 /dT, we obtain the coherence length ξ (0 ≈ 10 nm at T = 0 K and a coefficient of electronic heat capacity that is small compared with those of other oxide materials.

  16. Importing low-density ideas to high-density revitalisation

    DEFF Research Database (Denmark)

    Anrholtz, Jens; Ibsen, Christian Lyhne; Ibsen, Flemming

    2016-01-01

    Why did union officials from a high-union-density country like Denmark choose to import an organising strategy from low-density countries such as the US and the UK? Drawing on in-depth interviews with key union officials and internal documents, the authors of this article argue two key points. Fi...... cherry-pick some elements while leaving fundamental aspects out. The study nevertheless indicates that a lack of coherency and model-fit to Danish industrial relations might hamper the positive effects of the organising strategy....

  17. High Energy Density Capacitors Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Capacitor size and reliability are often limiting factors in pulse power, high speed switching, and power management and distribution (PMAD) systems. T/J...

  18. Electronic DC transformer with high power density

    NARCIS (Netherlands)

    Pavlovský, M.

    2006-01-01

    This thesis is concerned with the possibilities of increasing the power density of high-power dc-dc converters with galvanic isolation. Three cornerstones for reaching high power densities are identified as: size reduction of passive components, reduction of losses particularly in active components

  19. High regression rate, high density hybrid fuels Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This SBIR program will investigate high energy density novel nanofuels combined with high density binders for use with an N2O oxidizer. Terves has developed...

  20. Efficacy, but not antibody titer or affinity, of a heroin hapten conjugate vaccine correlates with increasing hapten densities on tetanus toxoid, but not on CRM197 carriers.

    Science.gov (United States)

    Jalah, Rashmi; Torres, Oscar B; Mayorov, Alexander V; Li, Fuying; Antoline, Joshua F G; Jacobson, Arthur E; Rice, Kenner C; Deschamps, Jeffrey R; Beck, Zoltan; Alving, Carl R; Matyas, Gary R

    2015-06-17

    Vaccines against drugs of abuse have induced antibodies in animals that blocked the biological effects of the drug by sequestering the drug in the blood and preventing it from crossing the blood-brain barrier. Drugs of abuse are too small to induce antibodies and, therefore, require conjugation of drug hapten analogs to a carrier protein. The efficacy of these conjugate vaccines depends on several factors including hapten design, coupling strategy, hapten density, carrier protein selection, and vaccine adjuvant. Previously, we have shown that 1 (MorHap), a heroin/morphine hapten, conjugated to tetanus toxoid (TT) and mixed with liposomes containing monophosphoryl lipid A [L(MPLA)] as adjuvant, partially blocked the antinociceptive effects of heroin in mice. Herein, we extended those findings, demonstrating greatly improved vaccine induced antinociceptive effects up to 3% mean maximal potential effect (%MPE). This was obtained by evaluating the effects of vaccine efficacy of hapten 1 vaccine conjugates with varying hapten densities using two different commonly used carrier proteins, TT and cross-reactive material 197 (CRM197). Immunization of mice with these conjugates mixed with L(MPLA) induced very high anti-1 IgG peak levels of 400-1500 μg/mL that bound to both heroin and its metabolites, 6-acetylmorphine and morphine. Except for the lowest hapten density for each carrier, the antibody titers and affinity were independent of hapten density. The TT carrier based vaccines induced long-lived inhibition of heroin-induced antinociception that correlated with increasing hapten density. The best formulation contained TT with the highest hapten density of ≥30 haptens/TT molecule and induced %MPE of approximately 3% after heroin challenge. In contrast, the best formulation using CRM197 was with intermediate 1 densities (10-15 haptens/CRM197 molecule), but the %MPE was approximately 13%. In addition, the chemical synthesis of 1, the optimization of the conjugation

  1. High energy density lithium batteries

    CERN Document Server

    Aifantis, Katerina E; Kumar, R Vasant

    2010-01-01

    Cell phones, portable computers and other electronic devices crucially depend on reliable, compact yet powerful batteries. Therefore, intensive research is devoted to improving performance and reducing failure rates. Rechargeable lithium-ion batteries promise significant advancement and high application potential for hybrid vehicles, biomedical devices, and everyday appliances. This monograph provides special focus on the methods and approaches for enhancing the performance of next-generation batteries through the use of nanotechnology. Deeper understanding of the mechanisms and strategies is

  2. High charge-carrier mobility enables exploitation of carrier multiplication in quantum-dot films

    NARCIS (Netherlands)

    Suchand Sandeep, C.S.; Ten Cate, S.; Schins, J.M.; Savenije, T.J.; Liu, Y.; Law, M.; Kinge, S.; Houtepen, A.J.; Siebbeles, L.D.A.

    2013-01-01

    Carrier multiplication, the generation of multiple electron–hole pairs by a single photon, is of great interest for solar cells as it may enhance their photocurrent. This process has been shown to occur efficiently in colloidal quantum dots, however, harvesting of the generated multiple charges has

  3. Approximate graphical method of solving Fermi level and majority carrier density of semiconductors with multiple donors and multiple acceptors

    Institute of Scientific and Technical Information of China (English)

    Ken K. Chin

    2011-01-01

    We present a generic approximate graphical method for determining the equilibrium Fermi level and majority carrier density of a semiconductor with multiple donors and multiple acceptors compensating each other Simple and easy-to-follow procedures of the graphical method are described. By graphically plotting two wrapping step functions facing each other, one for the positive hole-ionized donor and one for the negative electron-ionized acceptor, we have the crossing point that renders the Fermi level and majority carrier density. Using the graphica method, new equations are derived, such as the carrier compensation proportional to NA/ND, not the widely quoted NA - ND. Visual insight is offered to view not only the result of graphic determination of Fermi level and majoriy carrier density but also the dominant and critical pair of donors and acceptors in compensation. The graphica method presented in this work will help to guide the design, adjustment, and improvement of the multiply doped semiconductors. Comparison of this approximate graphical method with previous work on compensation, and with some experimental results, is made. Future work in the field is proposed.

  4. Charge carrier Density Imaging / IR lifetime mapping of Si wafers by Lock-In Thermography

    NARCIS (Netherlands)

    Van der Tempel, L.

    2012-01-01

    ABSTRACT Minority carrier lifetime imaging by lock-in thermography of passivated silicon wafers for photovoltaic cells has been developed for the public Pieken in de Delta project geZONd. CONCLUSIONS Minority carrier lifetime imaging by lock-in thermography of passivatedsilicon wafers is released

  5. Charge carrier Density Imaging / IR lifetime mapping of Si wafers by Lock-In Thermography

    NARCIS (Netherlands)

    Van der Tempel, L.

    2012-01-01

    ABSTRACT Minority carrier lifetime imaging by lock-in thermography of passivated silicon wafers for photovoltaic cells has been developed for the public Pieken in de Delta project geZONd. CONCLUSIONS Minority carrier lifetime imaging by lock-in thermography of passivatedsilicon wafers is released t

  6. Effect of reduction of trap charge carrier density in organic field effect transistors by surface treatment of dielectric layer

    Energy Technology Data Exchange (ETDEWEB)

    Dagar, Janardan; Yadav, Vandana; Kumar Singh, Rajiv; Suman, C. K.; Srivastava, Ritu, E-mail: ritu@mail.nplindia.org [Physics of Energy Harvesting Division, CSIR-National Physical Laboratory, CSIR-Network of Institute for Solar Energy (NISE), Dr. K.S.Krishnan Road, New Delhi 110012 (India); Tyagi, Priyanka [Physics of Energy Harvesting Division, CSIR-National Physical Laboratory, CSIR-Network of Institute for Solar Energy (NISE), Dr. K.S.Krishnan Road, New Delhi 110012 (India); Center for Applied Research in Electronics, Indian Institute of Technology Delhi, New Delhi 110016 (India)

    2013-12-14

    In this work, we have studied the effect of surface treatment of SiO{sub 2} dielectric layer on the reduction of the trap charge carrier density at dielectric/semiconducting interface by fabricating a metal–insulator–semiconductor (MIS) device using α, ω-dihexylcarbonylquaterthiophene as semiconducting layer. SiO{sub 2} dielectric layer has been treated with 1,1,1,3,3,3-hexamethyldisilazane (HMDS) to modify the chemical group acting as charge traps. Capacitance-voltage measurements have been performed on MIS devices fabricated on SiO{sub 2} and HMDS treated SiO{sub 2}. These data have been used for the calculation of trap charge carrier density and Debye length at the dielectric-semiconductor interface. The calculated trap charge carrier density has been found to reduce from (2.925 ± 0.049) × 10{sup 16} cm{sup −3} to (2.025 ± 0.061) × 10{sup 16} cm{sup −3} for the MIS device with HMDS treated SiO{sub 2} dielectric in comparison to that of untreated SiO{sub 2}. Next, the effect of reduction in trap charge carrier density has been studied on the performance of organic field effect transistors. The improvement in the device parameters like mobility, on/off ratio, and gate leakage current has been obtained with the effect of the surface treatment. The charge carrier mobility has been improved by a factor of 2 through this treatment. Further, the influence of the treatment was observed by atomic force microscope and Fourier transform infrared spectroscopy techniques.

  7. Influence of optical interference and carrier lifetime on the short circuit current density of organic bulk heterojunction solar cells

    Institute of Scientific and Technical Information of China (English)

    You Hai-Long; Zhang Chun-Fu

    2009-01-01

    Based on simple analytical equations, short circuit current density (Jsc) of the organic bulk heterojunction solar cells has been calculated. It is found that the optical interference effect plays a very important role in the determination of JSC;and obvious oscillatory behaviour of Jsc was observed as a function of thickness. At the same time, the influence of JSC only increases the carrier lifetime on JSC also cannot be neglected. When the carrier lifetime is relatively short, at the initial stage and then decreases rapidly with the increase of active layer thickness. However, for a relatively long carrier lifetime, the exciton dissociation probability must be considered, and Jsc behaves wave-like with the increase of active layer thickness. The validity of this model is confirmed by the experimental results.

  8. A code-aided carrier synchronization algorithm based on improved nonbinary low-density parity-check codes

    Science.gov (United States)

    Bai, Cheng-lin; Cheng, Zhi-hui

    2016-09-01

    In order to further improve the carrier synchronization estimation range and accuracy at low signal-to-noise ratio ( SNR), this paper proposes a code-aided carrier synchronization algorithm based on improved nonbinary low-density parity-check (NB-LDPC) codes to study the polarization-division-multiplexing coherent optical orthogonal frequency division multiplexing (PDM-CO-OFDM) system performance in the cases of quadrature phase shift keying (QPSK) and 16 quadrature amplitude modulation (16-QAM) modes. The simulation results indicate that this algorithm can enlarge frequency and phase offset estimation ranges and enhance accuracy of the system greatly, and the bit error rate ( BER) performance of the system is improved effectively compared with that of the system employing traditional NB-LDPC code-aided carrier synchronization algorithm.

  9. Density Estimation Trees in High Energy Physics

    CERN Document Server

    Anderlini, Lucio

    2015-01-01

    Density Estimation Trees can play an important role in exploratory data analysis for multidimensional, multi-modal data models of large samples. I briefly discuss the algorithm, a self-optimization technique based on kernel density estimation, and some applications in High Energy Physics.

  10. Modulated two-dimensional charge-carrier density in LaTiO3-layer-doped LaAlO3/SrTiO3 heterostructure.

    Science.gov (United States)

    Nazir, Safdar; Bernal, Camille; Yang, Kesong

    2015-03-11

    The highly mobile two-dimensional electron gas (2DEG) formed at the polar/nonpolar LaAlO3/SrTiO3 (LAO/STO) heterostructure (HS) is a matter of great interest because of its potential applications in nanoscale solid-state devices. To realize practical implementation of the 2DEG in device design, desired physical properties such as tuned charge carrier density and mobility are necessary. In this regard, polar perovskite-based transition metal oxides can act as doping layers at the interface and are expected to tune the electronic properties of 2DEG of STO-based HS systems dramatically. Herein, we investigated the doping effects of LaTiO3(LTO) layers on the electronic properties of 2DEG at n-type (LaO)(+1)/(TiO2)(0) interface in the LAO/STO HS using spin-polarized density functional theory calculations. Our results indicate an enhancement of orbital occupation near the Fermi energy, which increases with respect to the number of LTO unit cells, resulting in a higher charge carrier density of 2DEG than that of undoped system. The enhanced charge carrier density is attributed to an extra electron introduced by the Ti 3d(1) orbitals from the LTO dopant unit cells. This conclusion is consistent with the recent experimental findings (Appl. Phys. Lett. 2013, 102, 091601). Detailed charge density and partial density of states analysis suggests that the 2DEG in the LTO-doped HS systems primarily comes from partially occupied dyz and dxz orbitals.

  11. Highly mobile carriers in iron-based superconductors

    Science.gov (United States)

    Ovchenkov, Y. A.; Chareev, D. A.; Kulbachinskii, V. A.; Kytin, V. G.; Presnov, D. E.; Volkova, O. S.; Vasiliev, A. N.

    2017-03-01

    The field and temperature dependencies of the resistivity and Hall effect are measured for FeSe{}1-xS{}x (x = 0.04, 0.09, and 0.19) single crystals. Sample FeSe{}0.81S{}0.19 does not show a transition to an orthorhombic phase and at low temperatures exhibits transport properties, which are very different from those of orthorhombic samples. The behavior of FeSe{}0.81S{}0.19 is well described by the simple two-band model with comparable values of the hole and electron mobilities. The characteristics of the low-temperature transport properties of the orthorhombic Fe(SeS) samples are largely determined by the presence of a small number of highly mobile carriers, which may originate from the local regions of the Fermi surface, presumably, nearby the Van Hove singularity points. Our results, for the first time, demonstrate a strong evolution of a tiny band of highly mobile electrons at a tetragonal to orthorhombic quantum phase transition. The behavior of this band can be the reason for the diverging nematic susceptibility, determined from elastoresistivity, which is considered one of the most intriguing phenomena in the physics of iron-based superconductors.

  12. Institute for High Energy Density Science

    Energy Technology Data Exchange (ETDEWEB)

    Wootton, Alan [Univ. of Texas, Austin, TX (United States)

    2017-01-13

    The project objective was for the Institute of High Energy Density Science (IHEDS) at the University of Texas at Austin to help grow the High Energy Density (HED) science community, by connecting academia with the Z Facility (Z) and associated staff at Sandia National Laboratories (SNL). IHEDS was originally motivated by common interests and complementary capabilities at SNL and the University of Texas System (UTX), in 2008.

  13. Tuning the conductivity threshold and carrier density of two-dimensional electron gas at oxide interfaces through interface engineering

    Directory of Open Access Journals (Sweden)

    H. J. Harsan Ma

    2015-08-01

    Full Text Available The two-dimensional electron gas (2DEG formed at the perovskite oxides heterostructures is of great interest because of its potential applications in oxides electronics and nanoscale multifunctional devices. A canonical example is the 2DEG at the interface between a polar oxide LaAlO3 (LAO and non-polar SrTiO3 (STO. Here, the LAO polar oxide can be regarded as the modulating or doping layer and is expected to define the electronic properties of 2DEG at the LAO/STO interface. However, to practically implement the 2DEG in electronics and device design, desired properties such as tunable 2D carrier density are necessary. Here, we report the tuning of conductivity threshold, carrier density and electronic properties of 2DEG in LAO/STO heterostructures by insertion of a La0.5Sr0.5TiO3 (LSTO layer of varying thicknesses, and thus modulating the amount of polarization of the oxide over layers. Our experimental result shows an enhancement of carrier density up to a value of about five times higher than that observed at the LAO/STO interface. A complete thickness dependent metal-insulator phase diagram is obtained by varying the thickness of LAO and LSTO providing an estimate for the critical thickness needed for the metallic phase. The observations are discussed in terms of electronic reconstruction induced by polar oxides.

  14. Investigation of carriers of lustrous carbon at high temperatures

    Directory of Open Access Journals (Sweden)

    M. Holtzer

    2010-01-01

    Full Text Available Lustrous carbon is very important in processes of iron casting in green sand. Lustrous carbon (pirografit is a microcrystalline carbon form, which evolves from a gaseous phase. In the case of applying additions, generating lustrous carbon, for sands with bentonite, there is always a danger of emitting – due to a high temperature of liquid cast iron and a humidity -compounds hazardous for a human health. There can be: CO, SO2, benzene, toluene, ethylbenzene, xylene (the so-called: BTEX as well as polycyclic aromatic hydrocarbons (PAHs. In order to asses the selected mixtures: bentonite – carrier of lustrous carbon, in which a coal dust fraction was limited, the thermogravimetric analysis and the analysis of evolving gases were performed. Examinations were carried out in the Applications Laboratory NITZSCH-Gerätebau GmbH, Selb/Bavaria, Germany. The NETZSCH model STA 449 F3 Jupiter® simultaneous thermal analyzer was used to measure the mass change and transformation energetics of materials. The system employed for this work was equipped with an SiC furnace capable of operation from 25 to 1550°C. The mass spectrometer of the QMS 403 allows detection of mass numbers between 1 and 300 amu (atomic mass unit.

  15. High integrity carrier phase navigation using multiple civil GPS signals

    Science.gov (United States)

    Jung, Jaewoo

    2000-11-01

    A navigation system should guide users to their destinations accurately and reliably. Among the many available navigation aids, the Global Positioning System stands out due to its unique capabilities. It is a satellite-based navigation system which covers the entire Earth with horizontal accuracy of 20 meters for stand alone civil users. Today, the GPS provides only one civil signal, but two more signals will be available in the near future. GPS will provide a second signal at 1227.60 MHz (L2) and a third signal at 1176.45 MHz (Lc), in addition to the current signal at 1575.42 MHz (L1). The focus of this thesis is exploring the possibility of using beat frequencies of these signals to provide navigation aid to users with high accuracy and integrity. To achieve high accuracy, the carrier phase differential GPS is used. The integer ambiguity is resolved using the Cascade Integer Resolution (CIR), which is defined in this thesis. The CIR is an instantaneous, geometry-free integer resolution method utilizing beat frequencies of GPS signals. To insure high integrity, the probability of incorrect integer ambiguity resolution using the CIR is analyzed. The CIR can immediately resolve the Lc integer ambiguity up to 2.4 km from the reference receiver, the Widelane (L1-L2) integer ambiguity up to 22 km, and the Extra Widelane (L2-Lc) integer ambiguity from there on, with probability of incorrect integer resolution of 10-4 . The optimal use of algebraic combinations of multiple GPS signals are also investigated in this thesis. Finally, the gradient of residual differential ionospheric error is estimated to stimated to increase performance of the CIR.

  16. Strongly Interacting Matter at High Energy Density

    Energy Technology Data Exchange (ETDEWEB)

    McLerran,L.

    2008-09-07

    This lecture concerns the properties of strongly interacting matter (which is described by Quantum Chromodynamics) at very high energy density. I review the properties of matter at high temperature, discussing the deconfinement phase transition. At high baryon density and low temperature, large N{sub c} arguments are developed which suggest that high baryonic density matter is a third form of matter, Quarkyonic Matter, that is distinct from confined hadronic matter and deconfined matter. I finally discuss the Color Glass Condensate which controls the high energy limit of QCD, and forms the low x part of a hadron wavefunction. The Glasma is introduced as matter formed by the Color Glass Condensate which eventually thermalizes into a Quark Gluon Plasma.

  17. Spin polarization in high density quark matter

    DEFF Research Database (Denmark)

    Bohr, Henrik; Panda, Prafulla K.; Providênci, Constanca

    2013-01-01

    We investigate the occurrence of a ferromagnetic phase transition in high density hadronic matter (e.g., in the interior of a neutron star). This could be induced by a four-fermion interaction analogous to the one which is responsible for chiral symmetry breaking in the Nambu-Jona-Lasinio model......, to which it is related through a Fierz transformation. Flavor SU(2) and flavor SU(3) quark matter are considered. A second-order phase transition is predicted at densities about 5 times the normal nuclear matter density. It is also found that in flavor SU(3) quark matter, a first-order transition from...

  18. Modeling of sheet carrier density and microwave frequency characteristics in Spacer based AlGaN/AlN/GaN HEMT devices

    Science.gov (United States)

    Mohanbabu, A.; Anbuselvan, N.; Mohankumar, N.; Godwinraj, D.; Sarkar, C. K.

    2014-01-01

    In this paper, we present a physics-based model for two-dimensional electron gas (2DEG) sheet carrier density ns and various microwave characteristics such as transconductance, cut-off frequency (ft) of the proposed Spacer layer based AlxGa1-xN/AlN/GaN High Electron Mobility Transistors (HEMTs) is modeled by considering the quasi-triangular quantum well. To obtain charge density ns, the variation of Fermi level with supply voltage and the formation of various energy sub-bands E0, E1 are considered. The obtained results are simple and easy to analyze the sheet carrier density, DC model and microwave frequency performance analysis for nanoscale Spacer layer based AlxGa1-xN/AlN/GaN HEMT power devices. The Spacer layer based AlGaN/AlN/GaN heterostructure HEMTs shows excellent promise as one of the candidates to substitute present AlGaN/GaN HEMTs for future high speed and high power applications. Derived model results for drain current, transconductance, current-gain cutoff frequency for different short and long gate length device are calibrated and verified with experimental data over a full range for gate and drain applied voltages and is useful for nanoscale and microwave analysis for circuit design.

  19. The high density Z-pinch

    Energy Technology Data Exchange (ETDEWEB)

    McCall, G.H.

    1988-01-01

    During the past few years techniques have been developed for producing pinches in solid deuterium. The conditions which exist in these plasmas are quiet different from those produced earlier. The pinch is formed from a fiber of solid deuterium rather than from a low density gas, and the current is driven by a low impedance, high voltage pulse generator. Because of the high initial density, it is not necessary to compress the pinch to reach thermonuclear conditions, and the confinement time required for energy production is much shorter than for a gas. The experimental results, which have been verified by experiments performed at higher current were quite surprising and encouraging. The pinch appeared to be stable for a time much longer than the Alfven radial transit time. In this paper, however, I argue that the pinch is not strictly stable, but it does not appear to disassemble in a catastrophic fashion. It appears that there may be a distinction between stability and confinement in the high density pinch. In the discussion below I will present the status of the high density Z-pinch experiments at laboratories around the world, and I will describe some of the calculational and experimental results. I will confine my remarks to recent work on the high density pinch. 17 refs. 10 figs.

  20. Power density, field intensity, and carrier frequency determinants of RF-energy-induced calcium-ion efflux from brain tissue

    Energy Technology Data Exchange (ETDEWEB)

    Joines, W.T.; Blackman, C.F.

    1980-01-01

    To explain a carrier frequency dependence reported for radiofrequency (RF)-induced calcium-ion efflux from brain tissue, a chick-brain hemisphere bathed in buffer solution is modeled as a sphere within the uniform field of the incident electromagnetic wave. Calculations on a spherical model show that the average electric-field intensity within the sample remains the same at different carrier frequencies if the incident power density (Pi) is adjusted by an amount that compensates for the change in complex permittivity (epsilon *r) and the change of wavelength, as a function of carrier frequency. The resulting formula for transforming Pi is seen to follow the pattern of both positive and negative demonstrations of calcium-ion efflux that have been observed at carrier frequencies of 50, 147, and 450 MHz. Indeed, all results obtained at these three frequencies, when related by Pi's that produce the same average electric-field intensity within the sample, are seen to be in agreement; no prediction is contradicted by an experiment.

  1. High Density Metamaterials for Visible Light

    Science.gov (United States)

    2016-11-28

    Split Ring Resonator Metamaterials with Fundamental Magnetic Resonance in the Middle Visible Spectrum,” Adv. Opt. Mater., vol. 2, no. 3, pp. 280–285...AFRL-AFOSR-JP-TR-2016-0097 High density metamaterials for visible light Dao Hua Zhang NANYANG TECHNOLOGICAL UNIVERSITY Final Report 11/28/2016...COVERED (From - To)  16 Jul 2014 to 15 Jul 2016 4. TITLE AND SUBTITLE High density metamaterials for visible light 5a.  CONTRACT NUMBER 5b.  GRANT

  2. A quarksonic matter at high isospin density

    CERN Document Server

    Cao, Gaoqing; Huang, Xu-Guang

    2016-01-01

    Analogous to the quarkyonic matter at high baryon density in which the quark Fermi seas and the baryonic excitations coexist, it is argued that a "quarksonic matter" phase appears at high isospin density where the quark (antiquark) Fermi seas and the mesonic excitations coexist. We explore this phase in detail in both large $N_c$ and asymptotically free limits: In large $N_c$ limit, we sketch a phase diagram for the quarksonic matter. In the asymptotically free limit, we study the pion superfluidity and thermodynamics of the quarksonic matter by using both perturbative calculations and effective model.

  3. Nanoscale carrier injectors for high luminescence Si-based LEDs

    NARCIS (Netherlands)

    Piccolo, G.; Kovalgin, Alexeij Y.; Schmitz, Jurriaan

    2012-01-01

    In this paper we present the increased light emission for Sip–i–n light emitting diodes (LEDs) by geometrical scaling of the injector size for p- and n- type carriers. Simulations and electrical and optical characteristics of our realized devices support our findings. Reducing the injector size

  4. Nanoscale carrier injectors for high luminescence Si-based LEDs

    NARCIS (Netherlands)

    Piccolo, G.; Kovalgin, A.Y.; Schmitz, J.

    2012-01-01

    In this paper we present the increased light emission for Sip–i–n light emitting diodes (LEDs) by geometrical scaling of the injector size for p- and n- type carriers. Simulations and electrical and optical characteristics of our realized devices support our findings. Reducing the injector size decr

  5. Curie temperature of Co-doped TiO2 as functions of carrier density and Co content evaluated from electrical transport and magnetization at low temperature regime

    Directory of Open Access Journals (Sweden)

    Thantip S. Krasienapibal

    2016-05-01

    Full Text Available Curie temperature (TC of anatase Co-doped TiO2 epitaxial thin films was systematically investigated as functions of carrier density (n and Co content (x by electrical transport and magnetization measurements at low temperature regime. The estimated TC from both measurements showed similar TC. For x = 0.03, 0.05, and 0.07, non-monotonic TC vs. n relations were observed, whereas TC was monotonically increasing function of n for x = 0.10. Possible mechanism of high TC ferromagnetism for this compound was discussed.

  6. Graded Carrier Concentration Absorber Profile for High Efficiency CIGS Solar Cells

    Directory of Open Access Journals (Sweden)

    Antonino Parisi

    2015-01-01

    Full Text Available We demonstrate an innovative CIGS-based solar cells model with a graded doping concentration absorber profile, capable of achieving high efficiency values. In detail, we start with an in-depth discussion concerning the parametrical study of conventional CIGS solar cells structures. We have used the wxAMPS software in order to numerically simulate cell electrical behaviour. By means of simulations, we have studied the variation of relevant physical and chemical parameters—characteristic of such devices—with changing energy gap and doping density of the absorber layer. Our results show that, in uniform CIGS cell, the efficiency, the open circuit voltage, and short circuit current heavily depend on CIGS band gap. Our numerical analysis highlights that the band gap value of 1.40 eV is optimal, but both the presence of Molybdenum back contact and the high carrier recombination near the junction noticeably reduce the crucial electrical parameters. For the above-mentioned reasons, we have demonstrated that the efficiency obtained by conventional CIGS cells is lower if compared to the values reached by our proposed graded carrier concentration profile structures (up to 21%.

  7. Investigations on high speed directly modulated microdisk lasers accounting for radial carrier hole burning

    Science.gov (United States)

    Huang, Yong-Zhen; Lv, Xiao-Meng; Zou, Ling-Xiu; Long, Heng; Xiao, Jin-Long; Yang, Yue-De; Du, Yun

    2014-04-01

    High-speed modulation characteristics are investigated for microdisk lasers theoretically and experimentally. In rate equation analysis, the microdisk resonator is radially divided into two regions under uniform carrier density approximation in each region. The injection current profile, carrier spatial hole burning, and diffusion are accounted for in the evaluation of small-signal modulation curves and the simulation of large-signal responses. The numerical results indicate that a wide mode field pattern in radial direction has merit for high-speed modulation, which is expected for coupled modes in the microdisk lasers connected with an output waveguide. For a 15-μm-radius microdisk laser connected with a 2-μm-wide output waveguide, the measured small-signal response curves with a low-frequency roll-off are well in agreement with the simulated result at a 2-μm radial width for the mode intensity distribution. The resonant frequencies of 7.2, 5.9, and 3.9 GHz are obtained at the temperatures of 287, 298, and 312 K from the small-signal response curves, and clear eye diagrams at 12.5 Gb/s with an extinction ratio of 6.1 dB are observed for the microdisk laser at the biasing current of 38 mA and 287 K.

  8. High energy density in multisoliton collisions

    Science.gov (United States)

    Saadatmand, Danial; Dmitriev, Sergey V.; Kevrekidis, Panayotis G.

    2015-09-01

    Solitons are very effective in transporting energy over great distances and collisions between them can produce high energy density spots of relevance to phase transformations, energy localization and defect formation among others. It is then important to study how energy density accumulation scales in multisoliton collisions. In this study, we demonstrate that the maximal energy density that can be achieved in collision of N slowly moving kinks and antikinks in the integrable sine-Gordon field, remarkably, is proportional to N2, while the total energy of the system is proportional to N . This maximal energy density can be achieved only if the difference between the number of colliding kinks and antikinks is minimal, i.e., is equal to 0 for even N and 1 for odd N and if the pattern involves an alternating array of kinks and antikinks. Interestingly, for odd (even) N the maximal energy density appears in the form of potential (kinetic) energy, while kinetic (potential) energy is equal to zero. The results of the present study rely on the analysis of the exact multisoliton solutions for N =1 ,2 , and 3 and on the numerical simulation results for N =4 ,5 ,6 , and 7. The effect of weak Hamiltonian and non-Hamiltonian perturbations on the maximal energy density in multikink collisions is also discussed as well as that of the collision relative phase. Based on these results one can speculate that the soliton collisions in the sine-Gordon field can, in principle, controllably produce very high energy density. This can have important consequences for many physical phenomena described by the Klein-Gordon equations.

  9. Supernovae and high density nuclear matter

    Energy Technology Data Exchange (ETDEWEB)

    Kahana, S.

    1986-01-01

    The role of the nuclear equation of state (EOS) in producing prompt supernova explosions is examined. Results of calculations of Baron, Cooperstein, and Kahana incorporating general relativity and a new high density EOS are presented, and the relevance of these calculations to laboratory experiments with heavy ions considered. 31 refs., 6 figs., 2 tabs.

  10. High Gluon Densities in Heavy Ions Collisions

    CERN Document Server

    Blaizot, Jean-Paul

    2016-01-01

    The early stages of heavy ion collisions are dominated by high density systems of gluons that carry each a small fraction $x$ of the momenta of the colliding nucleons. A distinguishing feature of such systems is the phenomenon of "saturation" which tames the expected growth of the gluon density as the energy of the collision increases. The onset of saturation occurs at a particular transverse momentum scale, the "saturation momentum", that emerges dynamically and that marks the onset of non-linear gluon interactions. At high energy, and for large nuclei, the saturation momentum is large compared to the typical hadronic scale, making high density gluons amenable to a description with weak coupling techniques. This paper reviews some of the challenges faced in the study of such dense systems of small $x$ gluons, and of the progress made in addressing them. The focus is on conceptual issues, and the presentation is both pedagogical, and critical. Examples where high gluon density could play a visible role in hea...

  11. High Density GEOSAT/GM Altimeter Data

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The high density Geosat/GM altimeter data south of 30 S have finally arrived. In addition, ERS-1 has completed more than 6 cycles of its 35-day repeat track. These...

  12. Enhanced sheet carrier densities in polarization controlled AlInN/AlN/GaN/InGaN field-effect transistor on Si (111

    Directory of Open Access Journals (Sweden)

    J. Hennig

    2015-07-01

    Full Text Available We report on GaN based field-effect transistor (FET structures exhibiting sheet carrier densities of n = 2.9 1013 cm−2 for high-power transistor applications. By grading the indium-content of InGaN layers grown prior to a conventional GaN/AlN/AlInN FET structure control of the channel width at the GaN/AlN interface is obtained. The composition of the InGaN layer was graded from nominally xIn = 30 % to pure GaN just below the AlN/AlInN interface. Simulations reveal the impact of the additional InGaN layer on the potential well width which controls the sheet carrier density within the channel region of the devices. Benchmarking the InxGa1−xN/GaN/AlN/Al0.87In0.13N based FETs against GaN/AlN/AlInN FET reference structures we found increased maximum current densities of ISD = 1300 mA/mm (560 mA/mm. In addition, the InGaN layer helps to achieve broader transconductance profiles as well as reduced leakage currents.

  13. Enhanced sheet carrier densities in polarization controlled AlInN/AlN/GaN/InGaN field-effect transistor on Si (111)

    Energy Technology Data Exchange (ETDEWEB)

    Hennig, J., E-mail: jonas.hennig@ovgu.de; Dadgar, A.; Witte, H.; Bläsing, J.; Lesnik, A.; Strittmatter, A.; Krost, A. [Otto-von-Guericke-Universität Magdeburg, Universitätsplatz 2, 39106 Magdeburg (Germany)

    2015-07-15

    We report on GaN based field-effect transistor (FET) structures exhibiting sheet carrier densities of n = 2.9 10{sup 13} cm{sup −2} for high-power transistor applications. By grading the indium-content of InGaN layers grown prior to a conventional GaN/AlN/AlInN FET structure control of the channel width at the GaN/AlN interface is obtained. The composition of the InGaN layer was graded from nominally x{sub In} = 30 % to pure GaN just below the AlN/AlInN interface. Simulations reveal the impact of the additional InGaN layer on the potential well width which controls the sheet carrier density within the channel region of the devices. Benchmarking the In{sub x}Ga{sub 1−x}N/GaN/AlN/Al{sub 0.87}In{sub 0.13}N based FETs against GaN/AlN/AlInN FET reference structures we found increased maximum current densities of I{sub SD} = 1300 mA/mm (560 mA/mm). In addition, the InGaN layer helps to achieve broader transconductance profiles as well as reduced leakage currents.

  14. Variation of carrier concentration and interface trap density in 8MeV electron irradiated c-Si solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Bhat, Sathyanarayana, E-mail: asharao76@gmail.com; Rao, Asha, E-mail: asharao76@gmail.com [Department of Physics, Mangalore Institute of Technology and Engineering, Moodabidri, Mangalore-574225 (India); Krishnan, Sheeja [Department of Physics, Sri Devi Institute of Technology, Kenjar, Mangalore-574142 (India); Sanjeev, Ganesh [Microtron Centre, Department of Physics, Mangalore University, Mangalagangothri-574199 (India); Suresh, E. P. [Solar Panel Division, ISRO Satellite Centre, Bangalore-560017 (India)

    2014-04-24

    The capacitance and conductance measurements were carried out for c-Si solar cells, irradiated with 8 MeV electrons with doses ranging from 5kGy – 100kGy in order to investigate the anomalous degradation of the cells in the radiation harsh environments. Capacitance – Voltage measurements indicate that there is a slight reduction in the carrier concentration upon electron irradiation due to the creation of radiation induced defects. The conductance measurement results reveal that the interface state densities and the trap time constant increases with electron dose due to displacement damages in c-Si solar cells.

  15. Signal with Flat Phase Noise Using a Carrier and the Power Spectral Density of White Noise for Phase Noise Standards

    Science.gov (United States)

    Watabe, Ken-ichi; Yanagimachi, Shinya; Ikegami, Takeshi; Iida, Hitoshi; Shimada, Yozo

    2012-01-01

    We have realized a phase noise standard of a signal with a -100 dBc/Hz flat phase noise at 10 MHz for Fourier frequencies of 1 Hz to 100 kHz, which ensures traceability to the International System of Units (SI). The flat phase noise signal is produced using a carrier combined with white noise. To ensure traceability, both the flat phase noise signal power and the power spectral density of white noise are determined with a calibrated power meter and the noise standard, respectively. The flatness of the phase noise standard is within ±0.7 dB.

  16. In-plane heterostructures of Sb/Bi with high carrier mobility

    Science.gov (United States)

    Zhao, Pei; Wei, Wei; Sun, Qilong; Yu, Lin; Huang, Baibiao; Dai, Ying

    2017-06-01

    In-plane two-dimensional (2D) heterostructures have been attracting public attention due to their distinctive properties. However, the pristine materials that can form in-plane heterostructures are reported only for graphene, hexagonal BN, transition-metal dichalcogenides. It will be of great significance to explore more suitable 2D materials for constructing such ingenious heterostructures. Here, we demonstrate two types of novel seamless in-plane heterostructures combined by pristine Sb and Bi monolayers by means of first-principle approach based on density functional theory. Our results indicate that external strain can serve as an effective strategy for bandgap engineering, and the transition from semiconductor to metal occurs when a compressive strain of -8% is applied. In addition, the designed heterostructures possess direct band gaps with high carrier mobility (˜4000 cm2 V-1 s-1). And the mobility of electrons and holes have huge disparity along the direction perpendicular to the interface of Sb/Bi in-plane heterostructures. It is favorable for carriers to separate spatially. Finally, we find that the band edge positions of Sb/Bi in-plane heterostructures can meet the reduction potential of hydrogen generation in photocatalysis. Our results not only offer alternative materials to construct versatile in-plane heterostructures, but also highlight the applications of 2D in-plane heterostructures in diverse nanodevices and photocatalysis.

  17. Anomalous enhancement of the sheet carrier density beyond the classic limit on a SrTiO3 surface

    Science.gov (United States)

    Kumar, Neeraj; Kitoh, Ai; Inoue, Isao H.

    2016-05-01

    Electrostatic carrier accumulation on an insulating (100) surface of SrTiO3 by fabricating a field effect transistor with Parylene-C (6 nm)/HfO2 (20 nm) bilayer gate insulator has revealed a mystifying phenomenon: sheet carrier density is about 10 times as large as ( is the sheet capacitance of the gate insulator, VG is the gate voltage, and e is the elementary charge). The channel is so clean to exhibit small subthreshod swing of 170 mV/decade and large mobility of 11 cm2/Vs for of 1 × 1014 cm‑2 at room temperature. Since does not depend on either VG nor time duration, beyond is solely ascribed to negative charge compressibility of the carriers, which was in general considered as due to exchange interactions among electrons in the small limit. However, the observed is too large to be naively understood by the framework. Alternative ideas are proposed in this work.

  18. Targeted carrier screening for four recessive disorders: high detection rate within a founder population.

    Science.gov (United States)

    Mathijssen, Inge B; Henneman, Lidewij; van Eeten-Nijman, Janneke M C; Lakeman, Phillis; Ottenheim, Cecile P E; Redeker, Egbert J W; Ottenhof, Winnie; Meijers-Heijboer, Hanne; van Maarle, Merel C

    2015-03-01

    In a genetically isolated community in the Netherlands four severe recessive genetic disorders occur at relatively high frequency (pontocerebellar hypoplasia type 2 (PCH2), fetal akinesia deformation sequence (FADS), rhizomelic chondrodysplasia punctata type 1 (RCDP1), and osteogenesis imperfecta (OI) type IIB/III. Over the past decades multiple patients with these disorders have been identified. This warranted the start of a preconception outpatient clinic, in 2012, aimed at couples planning a pregnancy. The aim of our study was to evaluate the offer of targeted genetic carrier screening as a method to identify high-risk couples for having affected offspring in this high-risk subpopulation. In one year, 203 individuals (92 couples and 19 individuals) were counseled. In total, 65 of 196 (33.2%) tested individuals were carriers of at least one disease, five (7.7%) of them being carriers of two diseases. Carrier frequencies of PCH2, FADS, RCDP1, and OI were 14.3%, 11.2%, 6.1%, and 4.1% respectively. In individuals with a positive family history for one of the diseases, the carrier frequency was 57.8%; for those with a negative family history this was 25.8%. Four PCH2 carrier-couples were identified. Thus, targeted (preconception) carrier screening in this genetically isolated population in which a high prevalence of specific disorders occurs detects a high number of carriers, and is likely to be more effective compared to cascade genetic testing. Our findings and set-up can be seen as a model for carrier screening in other high-risk subpopulations and contributes to the discussion about the way carrier screening can be offered and organized in the general population.

  19. Two-color QCD at high density

    Energy Technology Data Exchange (ETDEWEB)

    Boz, Tamer; Skullerud, Jon-Ivar [Department of Mathematical Physics, Maynooth University, Maynooth, Co. Kildare (Ireland); Centre for the Subatomic Structure of Matter, Adelaide University, Adelaide, SA 5005 (Australia); Giudice, Pietro [Universität Münster, Institut für Theoretische Physik, Münster (Germany); Hands, Simon [Department of Physics, College of Science, Swansea University, Swansea (United Kingdom); Williams, Anthony G. [Centre for the Subatomic Structure of Matter, Adelaide University, Adelaide, SA 5005 (Australia)

    2016-01-22

    QCD at high chemical potential has interesting properties such as deconfinement of quarks. Two-color QCD, which enables numerical simulations on the lattice, constitutes a laboratory to study QCD at high chemical potential. Among the interesting properties of two-color QCD at high density is the diquark condensation, for which we present recent results obtained on a finer lattice compared to previous studies. The quark propagator in two-color QCD at non-zero chemical potential is referred to as the Gor’kov propagator. We express the Gor’kov propagator in terms of form factors and present recent lattice simulation results.

  20. Charging effects on the carrier mobility in silicon-on-insulator wafers covered with a high-k layer

    Science.gov (United States)

    Halley, D.; Norga, G.; Guiller, A.; Fompeyrine, J.; Locquet, J. P.; Drechsler, U.; Siegwart, H.; Rossel, C.

    2003-11-01

    The carrier mobility μ in low-doped silicon-on-insulator wafers is found to be strongly modified by the deposition of a thin ZrO2 or SrZrO3 top layer grown by molecular-beam epitaxy. Pseudo-metal-oxide-semiconductor field-effect-transistor measurements performed on several samples clearly show a correlation between μ and the density of interface traps (Dit) at the Si/buried-oxide interface. The reduction of Dit by a forming gas anneal leads to a corresponding increase in mobility. Moreover, the high-k/Si interface can contribute to the total drain current via the creation of an inversion channel induced by trapped charges in the high-k layer. Using Hall-effect measurements, we took advantage of this additional current to evaluate the carrier mobility at the high-k/Si interface, without the need of a top gate electrode.

  1. Investigations of the drift mobility of carriers and density of states in nanocrystalline CdS thin films

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Baljinder [Department of Physics, Kurukshetra University, Kurukshetra 136119 (India); Department of Physics, Panjab University, Chandigarh 160014 (India); Singh, Janpreet; Kaur, Jagdish [Department of Physics, Panjab University, Chandigarh 160014 (India); Moudgil, R.K. [Department of Physics, Kurukshetra University, Kurukshetra 136119 (India); Tripathi, S.K., E-mail: surya@pu.ac.in [Department of Physics, Panjab University, Chandigarh 160014 (India)

    2016-06-01

    Nanocrystalline Cadmium Sulfide (nc-CdS) thin films have been prepared on well-cleaned glass substrate at room temperature (300 K) by thermal evaporation technique using inert gas condensation (IGC) method. X-ray diffraction (XRD) analysis reveals that the films crystallize in hexagonal structure with preferred orientation along [002] direction. Scanning electron microscope (SEM) and Transmission electron microscope (TEM) studies reveal that grains are spherical in shape and uniformly distributed over the glass substrates. The optical band gap of the film is estimated from the transmittance spectra. Electrical parameters such as Hall coefficient, carrier type, carrier concentration, resistivity and mobility are determined using Hall measurements at 300 K. Transit time and mobility are estimated from Time of Flight (TOF) transient photocurrent technique in gap cell configuration. The measured values of electron drift mobility from TOF and Hall measurements are of the same order. Constant Photocurrent Method in ac-mode (ac-CPM) is used to measure the absorption spectra in low absorption region. By applying derivative method, we have converted the measured absorption data into a density of states (DOS) distribution in the lower part of the energy gap. The value of Urbach energy, steepness parameter and density of defect states have been calculated from the absorption and DOS spectra.

  2. Method of high-density foil fabrication

    Energy Technology Data Exchange (ETDEWEB)

    Blue, Craig A.; Sikka, Vinod K.; Ohriner, Evan K.

    2003-12-16

    A method for preparing flat foils having a high density includes the steps of mixing a powdered material with a binder to form a green sheet. The green sheet is exposed to a high intensity radiative source adapted to emit radiation of wavelengths corresponding to an absorption spectrum of the powdered material. The surface of the green sheet is heated while a lower sub-surface temperature is maintained. An apparatus for preparing a foil from a green sheet using a radiation source is also disclosed.

  3. HIGH DENSITY QCD WITH HEAVY-IONS

    CERN Multimedia

    The Addendum 1 to Volume 2 of the CMS Physics TDR has been published The Heavy-Ion analysis group completed the writing of a TDR summarizing the CMS plans in using heavy ion collisions to study high density QCD. The document was submitted to the LHCC in March and presented in the Open Session of the LHCC on May 9th. The study of heavy-ion physics at the LHC is promising to be very exciting. LHC will open a new energy frontier in ultra-relativistic heavy-ion physics. The collision energy of heavy nuclei at sNN = 5.5 TeV will be thirty times larger than what is presently available at RHIC. We will certainly probe quark and gluon matter at unprecedented values of energy density. The prime goal of this research programme is to study the fundamental theory of the strong interaction - Quantum Chromodynamics (QCD) - in extreme conditions of temperature, density and parton momentum fraction (low-x). Such studies, with impressive experimental and theoretical advances in recent years thanks to the wealth of high-qua...

  4. Determination of minority-carrier lifetime and surface recombination velocity with high spacial resolution

    Science.gov (United States)

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

    1977-01-01

    Quantitative analysis of the electron beam induced current in conjunction with high-resolution scanning makes it possible to evaluate the minority-carrier lifetime three dimensionally in the bulk and the surface recombination velocity two dimensionally, with a high spacial resolution. The analysis is based on the concept of the effective excitation strength of the carriers which takes into consideration all possible recombination sources. Two-dimensional mapping of the surface recombination velocity of phosphorus-diffused silicon diodes is presented as well as a three-dimensional mapping of the changes in the minority-carrier lifetime in ion-implanted silicon.

  5. Slow cooling and highly efficient extraction of hot carriers in colloidal perovskite nanocrystals

    Science.gov (United States)

    Li, Mingjie; Bhaumik, Saikat; Goh, Teck Wee; Kumar, Muduli Subas; Yantara, Natalia; Grätzel, Michael; Mhaisalkar, Subodh; Mathews, Nripan; Sum, Tze Chien

    2017-02-01

    Hot-carrier solar cells can overcome the Schottky-Queisser limit by harvesting excess energy from hot carriers. Inorganic semiconductor nanocrystals are considered prime candidates. However, hot-carrier harvesting is compromised by competitive relaxation pathways (for example, intraband Auger process and defects) that overwhelm their phonon bottlenecks. Here we show colloidal halide perovskite nanocrystals transcend these limitations and exhibit around two orders slower hot-carrier cooling times and around four times larger hot-carrier temperatures than their bulk-film counterparts. Under low pump excitation, hot-carrier cooling mediated by a phonon bottleneck is surprisingly slower in smaller nanocrystals (contrasting with conventional nanocrystals). At high pump fluence, Auger heating dominates hot-carrier cooling, which is slower in larger nanocrystals (hitherto unobserved in conventional nanocrystals). Importantly, we demonstrate efficient room temperature hot-electrons extraction (up to ~83%) by an energy-selective electron acceptor layer within 1 ps from surface-treated perovskite NCs thin films. These insights enable fresh approaches for extremely thin absorber and concentrator-type hot-carrier solar cells.

  6. Utilization of a Buffered Dielectric to Achieve High Field-Effect Carrier Mobility in Graphene Transistors

    OpenAIRE

    Farmer, Damon B.; Chiu, Hsin-Ying; Lin, Yu-Ming; Jenkins, Keith A.; Xia, Fengnian; Avouris, Phaedon

    2009-01-01

    We utilize an organic polymer buffer layer between graphene and conventional gate dielectrics in top-gated graphene transistors. Unlike other insulators, this dielectric stack does not significantly degrade carrier mobility, allowing for high field-effect mobilities to be retained in top-gate operation. This is demonstrated in both two-point and four-point analysis, and in the high-frequency operation of a graphene transistor. Temperature dependence of the carrier mobility suggests that phono...

  7. High Spectral Density Optical Communication Technologies

    CERN Document Server

    Nakazawa, Masataka; Miyazaki, Tetsuya

    2010-01-01

    The latest hot topics of high-spectral density optical communication systems using digital coherent optical fibre communication technologies are covered by this book. History and meaning of a "renaissance" of the technology, requirements to the Peta-bit/s class "new generation network" are also covered in the first part of this book. The main topics treated are electronic and optical devices, digital signal processing including forward error correction, modulation formats as well as transmission and application systems. The book serves as a reference to researchers and engineers.

  8. Beyond the local density approximation : improving density functional theory for high energy density physics applications.

    Energy Technology Data Exchange (ETDEWEB)

    Mattsson, Ann Elisabet; Modine, Normand Arthur; Desjarlais, Michael Paul; Muller, Richard Partain; Sears, Mark P.; Wright, Alan Francis

    2006-11-01

    A finite temperature version of 'exact-exchange' density functional theory (EXX) has been implemented in Sandia's Socorro code. The method uses the optimized effective potential (OEP) formalism and an efficient gradient-based iterative minimization of the energy. The derivation of the gradient is based on the density matrix, simplifying the extension to finite temperatures. A stand-alone all-electron exact-exchange capability has been developed for testing exact exchange and compatible correlation functionals on small systems. Calculations of eigenvalues for the helium atom, beryllium atom, and the hydrogen molecule are reported, showing excellent agreement with highly converged quantumMonte Carlo calculations. Several approaches to the generation of pseudopotentials for use in EXX calculations have been examined and are discussed. The difficult problem of finding a correlation functional compatible with EXX has been studied and some initial findings are reported.

  9. Ti-doped indium tin oxide thin films for transparent field-effect transistors: control of charge-carrier density and crystalline structure.

    Science.gov (United States)

    Kim, Ji-In; Ji, Kwang Hwan; Jang, Mi; Yang, Hoichang; Choi, Rino; Jeong, Jae Kyeong

    2011-07-01

    Indium tin oxide (ITO) films are representative transparent conducting oxide media for organic light-emitting diodes, liquid crystal displays, and solar cell applications. Extending the utility of ITO films from passive electrodes to active channel layers in transparent field-effect transistors (FETs), however, has been largely limited because of the materials' high carrier density (>1 × 10(20) cm(-3)), wide band gap, and polycrystalline structure. Here, we demonstrate that control over the cation composition in ITO-based oxide films via solid doping of titanium (Ti) can optimize the carrier concentration and suppress film crystallization. On 120 nm thick SiO(2)/Mo (200 nm)/glass substrates, transparent n-type FETs prepared with 4 at % Ti-doped ITO films and fabricated via the cosputtering of ITO and TiO(2) exhibited high electron mobilities of 13.4 cm(2) V(-1) s(-1), a low subthreshold gate swing of 0.25 V decade(-1), and a high I(on/)I(off) ratio of >1 × 10(8).

  10. Recycling of irradiated high-density polyethylene

    Science.gov (United States)

    Navratil, J.; Manas, M.; Mizera, A.; Bednarik, M.; Stanek, M.; Danek, M.

    2015-01-01

    Radiation crosslinking of high-density polyethylene (HDPE) is a well-recognized modification of improving basic material characteristics. This research paper deals with the utilization of electron beam irradiated HDPE (HDPEx) after the end of its lifetime. Powder of recycled HDPEx (irradiation dose 165 kGy) was used as a filler into powder of virgin low-density polyethylene (LDPE) in concentrations ranging from 10% to 60%. The effect of the filler on processability and mechanical behavior of the resulting mixtures was investigated. The results indicate that the processability, as well as mechanical behavior, highly depends on the amount of the filler. Melt flow index dropped from 13.7 to 0.8 g/10 min comparing the lowest and the highest concentration; however, the higher shear rate the lower difference between each concentration. Toughness and hardness, on the other hand, grew with increasing addition of the recycled HDPEx. Elastic modulus increased from 254 to 450 MPa and material hardness increased from 53 to 59 ShD. These results indicate resolving the problem of further recycling of irradiated polymer materials while taking advantage of the improved mechanical properties.

  11. High Energy Density aluminum/oxygen cell

    Science.gov (United States)

    Rudd, E. J.; Gibbons, D. W.

    An alternative to a secondary battery as the power source for vehicle propulsion is a fuel cell, an example of which is the metal/air cell using metals such as aluminum, zinc, or iron. Aluminum is a particularly attractive candidate, with high energy and power densities, environmentally acceptable and having a large, established industrial base for production and distribution. An aluminum/oxygen system is currently under development for a prototype unmanned, undersea vehicle (UUV) for the US navy and recent work has focussed upon low corrosion aluminum alloys, and an electrolyte management system for processing the by-products of the energy-producing reactions. This paper summarizes the progress made in both areas. Anode materials capable of providing high utilization factors over current densities ranging from 5 to 150 mA/cm 2 have been identified, such materials being essential to realize mission life for the UUV. With respect to the electrolyte management system, a filter/precipitator unit has been successfully operated for over 250 h in a large scale, half-cell system.

  12. Diffuse Surface Scattering and Quantum Size Effects in the Surface Plasmon Resonances of Low Carrier Density Nanocrystals

    CERN Document Server

    Monreal, R Carmina; Apell, S Peter

    2016-01-01

    The detailed understanding of the physical parameters that determine Localized Surface Plasmon Resonances (LSPRs) is essential to develop new applications for plasmonics. A relatively new area of research has been opened by the identification of LSPRs in low carrier density systems obtained by doping semiconductor quantum dots. We investigate theoretically how diffuse surface scattering of electrons in combination with the effect of quantization due to size (QSE) impact the evolution of the LSPRs with the size of these nanosystems. Two key parameters are the length $R_0$ giving the strength of the QSE and the velocity $\\beta_T$ of the electronic excitations entering in the length scale for diffuse surface scattering. While the QSE itself only produces a blueshift in energy of the LSPRs, the diffuse surface scattering mechanism gives to both energy and linewidth an oscillatory-damped behavior as a function of size, with characteristic lengths that depend on material parameters. Thus, the evolution of the LSPRs...

  13. A high density two-dimensional electron gas in an oxide heterostructure on Si (001

    Directory of Open Access Journals (Sweden)

    E. N. Jin

    2014-11-01

    Full Text Available We present the growth and characterization of layered heterostructures comprised of LaTiO3 and SrTiO3 epitaxially grown on Si (001. Magnetotransport measurements show that the sheet carrier densities of the heterostructures scale with the number of LaTiO3/SrTiO3 interfaces, consistent with the presence of an interfacial 2-dimensional electron gas (2DEG at each interface. Sheet carrier densities of 8.9 × 1014 cm−2 per interface are observed. Integration of such high density oxide 2DEGs on silicon provides a bridge between the exceptional properties and functionalities of oxide 2DEGs and microelectronic technologies.

  14. Ground state of high-density matter

    Science.gov (United States)

    Copeland, ED; Kolb, Edward W.; Lee, Kimyeong

    1988-01-01

    It is shown that if an upper bound to the false vacuum energy of the electroweak Higgs potential is satisfied, the true ground state of high-density matter is not nuclear matter, or even strange-quark matter, but rather a non-topological soliton where the electroweak symmetry is exact and the fermions are massless. This possibility is examined in the standard SU(3) sub C tensor product SU(2) sub L tensor product U(1) sub Y model. The bound to the false vacuum energy is satisfied only for a narrow range of the Higgs boson masses in the minimal electroweak model (within about 10 eV of its minimum allowed value of 6.6 GeV) and a somewhat wider range for electroweak models with a non-minimal Higgs sector.

  15. Nanotechnology for Synthetic High Density Lipoproteins

    Science.gov (United States)

    Luthi, Andrea J.; Patel, Pinal C.; Ko, Caroline H.; Mutharasan, R. Kannan; Mirkin, Chad A.; Thaxton, C. Shad

    2014-01-01

    Atherosclerosis is the disease mechanism responsible for coronary heart disease (CHD), the leading cause of death worldwide. One strategy to combat atherosclerosis is to increase the amount of circulating high density lipoproteins (HDL), which transport cholesterol from peripheral tissues to the liver for excretion. The process, known as reverse cholesterol transport, is thought to be one of the main reasons for the significant inverse correlation observed between HDL blood levels and the development of CHD. This article highlights the most common strategies for treating atherosclerosis using HDL. We further detail potential treatment opportunities that utilize nanotechnology to increase the amount of HDL in circulation. The synthesis of biomimetic HDL nanostructures that replicate the chemical and physical properties of natural HDL provides novel materials for investigating the structure-function relationships of HDL and for potential new therapeutics to combat CHD. PMID:21087901

  16. High power density carbonate fuel cell

    Energy Technology Data Exchange (ETDEWEB)

    Yuh, C.; Johnsen, R.; Doyon, J.; Allen, J. [Energy Research Corp., Danbury, CT (United States)

    1996-12-31

    Carbonate fuel cell is a highly efficient and environmentally clean source of power generation. Many organizations worldwide are actively pursuing the development of the technology. Field demonstration of multi-MW size power plant has been initiated in 1996, a step toward commercialization before the turn of the century, Energy Research Corporation (ERC) is planning to introduce a 2.85MW commercial fuel cell power plant with an efficiency of 58%, which is quite attractive for distributed power generation. However, to further expand competitive edge over alternative systems and to achieve wider market penetration, ERC is exploring advanced carbonate fuel cells having significantly higher power densities. A more compact power plant would also stimulate interest in new markets such as ships and submarines where space limitations exist. The activities focused on reducing cell polarization and internal resistance as well as on advanced thin cell components.

  17. Band gap tunning in BN-doped graphene systems with high carrier mobility

    KAUST Repository

    Kaloni, T. P.

    2014-02-17

    Using density functional theory, we present a comparative study of the electronic properties of BN-doped graphene monolayer, bilayer, trilayer, and multilayer systems. In addition, we address a superlattice of pristine and BN-doped graphene. Five doping levels between 12.5% and 75% are considered, for which we obtain band gaps from 0.02 eV to 2.43 eV. We demonstrate a low effective mass of the charge carriers.

  18. Temperature dependence of the optical properties of high-density GaAs quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Ryan P.; Kim, Jongsu [Yeungnam University, Gyeongsan (Korea, Republic of); Lee, Sangjun; Noh, Samkyu [Korea Research Institute of Standards and Science, Daejeon (Korea, Republic of); Kim, Jinsoo [Chonbuk National University, Jeonju (Korea, Republic of); Leem, Jaeyoung [Inje University, Gimhae (Korea, Republic of); Song, Jindong [Korea Institute of Science and Technology, Seoul (Korea, Republic of)

    2012-05-15

    We investigate the effect of the quantum dot (QD) density on the thermal escape and the retrapping processes of carriers for unstrained GaAs/AlGaAs QDs through temperature-dependent photoluminescence measurements. We fabricated high-density GaAs QDs (8.4 x 10{sup 10}/cm{sup 2}, dot-dot distance ∼34 nm) on an Al{sub 0.3}Ga{sub 0.7}As/GaAs (111)A surface by using droplet epitaxy. The average lateral size and height of the GaAs QDs are 24 and 6 nm, respectively. Temperature-dependent photoluminescence (PL) studies show that high-density GaAs QDs undergo a sigmoidal-shape energy shift. The sigmoidal dependence of the PL peak energy can be explained by thermal escaping of carriers followed by re-trapping by QDs. Our analysis indicates that the re-trapping probability of thermally-escaped carriers increases with decreasing dot-to-dot distance (corresponding to an increase in the QD density).

  19. Modeling and analysis of the three-dimensional current density in sandwich-type single-carrier devices of disordered organic semiconductors

    Science.gov (United States)

    van der Holst, J. J. M.; Uijttewaal, M. A.; Balasubramanian, R.; Coehoorn, R.; Bobbert, P. A.; de Wijs, G. A.; de Groot, R. A.

    2009-02-01

    We present the results of a modeling study of the three-dimensional current density in single-carrier sandwich-type devices of disordered organic semiconductors. The calculations are based on a master-equation approach, assuming a Gaussian distribution of site energies without spatial correlations. The injection-barrier lowering due to the image potential is taken into account, so that the model provides a comprehensive treatment of the space-charge-limited current as well as the injection-limited current (ILC) regimes. We show that the current distribution can be highly filamentary for voltages, layer thicknesses, and disorder strengths that are realistic for organic light-emitting diodes and, that, as a result, the current density in both regimes can be significantly larger than as obtained from a one-dimensional continuum drift-diffusion device model. For devices with large injection barriers and strong disorder, in the ILC transport regime, good agreement is obtained with the average current density predicted from a model assuming injection and transport via one-dimensional filaments [A. L. Burin and M. A. Ratner, J. Chem. Phys. 113, 3941 (2000)].

  20. Abnormal high density lipoproteins in cerebrotendinous xanthomatosis

    Energy Technology Data Exchange (ETDEWEB)

    Shore, V. (Lawrence Livermore Lab., CA); Salen, G.; Cheng, F.W.; Forte, T.; Shefer, S.; Tint, G.S.

    1981-11-01

    The plasma lipoprotein profiles and high density lipoproteins (HDL) were characterized in patients with the genetic disease cerebrotendinous xanthomatosis (CTX). The mean HDL-cholesterol concentration in the CTX plasmas was 14.5 +/- 3.2 mg/dl, about one-third the normal value. The low HDL-cholesterol reflects a low concentration and an abnormal lipid composition of the plasma HDL. Relative to normal HDL, the cholesteryl esters are low, free cholesterol and phospholipids essentially normal, and triglycerides increased. The ratio of apoprotein (apo) to total cholesterol in the HDL of CTX was two to three times greater than normal. In the CTX HDL, the ratio of apoAI to apoAII was high, the proportion of apoC low, and a normally minor form of apoAI increased relative to other forms. The HDL in electron micrographs appeared normal morphologically and in particle size. The adnormalities in lipoprotein distribution profiles and composition of the plasma HDL result from metabolic defects that are not understood but may be linked to the genetic defect in bile acid synthesis in CTX. As a consequence, it is probable that the normal functions of the HDL, possibly including modulation of LDL-cholesterol uptake and the removal of excess cholesterol from peripheral tissues, are perturbed significantly in this disease.

  1. High Energy Density Capacitors for Pulsed Power Applications

    Science.gov (United States)

    2009-07-01

    high energy density energy storage capacitors. High efficency capacitors are available with energy densities as high as 3 J/cc for 1000 shots or...GENERAL ATOMICS ENERGY PRODUCTS Engineering Bulletin HIGH ENERGY DENSITY CAPACITORS FOR PULSED POWER APPLICATIONS Fred MacDougall, Joel...00-2009 4. TITLE AND SUBTITLE High Energy Density Capacitors for Pulsed Power Applications 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM

  2. Nanobiotechnology applications of reconstituted high density lipoprotein.

    Science.gov (United States)

    Ryan, Robert O

    2010-12-01

    High-density lipoprotein (HDL) plays a fundamental role in the Reverse Cholesterol Transport pathway. Prior to maturation, nascent HDL exist as disk-shaped phospholipid bilayers whose perimeter is stabilized by amphipathic apolipoproteins. Methods have been developed to generate reconstituted (rHDL) in vitro and these particles have been used in a variety of novel ways. To differentiate between physiological HDL particles and non-natural rHDL that have been engineered to possess additional components/functions, the term nanodisk (ND) is used. In this review, various applications of ND technology are described, such as their use as miniature membranes for solubilization and characterization of integral membrane proteins in a native like conformation. In other work, ND harboring hydrophobic biomolecules/drugs have been generated and used as transport/delivery vehicles. In vitro and in vivo studies show that drug loaded ND are stable and possess potent biological activity. A third application of ND is their use as a platform for incorporation of amphiphilic chelators of contrast agents, such as gadolinium, used in magnetic resonance imaging. Thus, it is demonstrated that the basic building block of plasma HDL can be repurposed for alternate functions.

  3. Photovoltaic retinal prosthesis with high pixel density

    Science.gov (United States)

    Mathieson, Keith; Loudin, James; Goetz, Georges; Huie, Philip; Wang, Lele; Kamins, Theodore I.; Galambos, Ludwig; Smith, Richard; Harris, James S.; Sher, Alexander; Palanker, Daniel

    2012-06-01

    Retinal degenerative diseases lead to blindness due to loss of the `image capturing' photoreceptors, while neurons in the `image-processing' inner retinal layers are relatively well preserved. Electronic retinal prostheses seek to restore sight by electrically stimulating the surviving neurons. Most implants are powered through inductive coils, requiring complex surgical methods to implant the coil-decoder-cable-array systems that deliver energy to stimulating electrodes via intraocular cables. We present a photovoltaic subretinal prosthesis, in which silicon photodiodes in each pixel receive power and data directly through pulsed near-infrared illumination and electrically stimulate neurons. Stimulation is produced in normal and degenerate rat retinas, with pulse durations of 0.5-4 ms, and threshold peak irradiances of 0.2-10 mW mm-2, two orders of magnitude below the ocular safety limit. Neural responses were elicited by illuminating a single 70 µm bipolar pixel, demonstrating the possibility of a fully integrated photovoltaic retinal prosthesis with high pixel density.

  4. Galaxy interactions II: High density environments

    CERN Document Server

    Alonso, Sol; Padilla, Nelson; Lambas, Diego G

    2011-01-01

    With the aim to assess the role of dense environments in galaxy interactions, properties we present an analysis of close galaxy pairs in groups and clusters, obtained from the Sloan Digital Sky Survey Data Release 7 (SDSS-DR7). We identified pairs that reside in groups by cross-correlating the total galaxy pair catalogue with the SDSS-DR7 group catalogue from Zapata et al. (2009). We classify pair galaxies according to the intensity of interaction. We analysed the effect of high density environments on different classes of galaxy-galaxy interactions and we have also studied the impact of the group global environment on pair galaxies. We find that galaxy pairs are more concentrated towards the group centres with respect to the other group galaxy members, and disturbed pairs show a preference to contain the brightest galaxy in the groups. The color-magnitude relation exhibits significant differences between pair galaxies and the control sample, consisting in color tails with a clear excess of extremely blue and...

  5. Strangeness production in high density baryon matter

    CERN Document Server

    Ganz, R E

    1999-01-01

    Strangeness production in heavy-ion collisions, when compared to proton proton collisions, is potentially a sensitive probe for collective energy deposition and therefore for reaction mechanisms in general. It may therefore provide insight into possible QGP formation in dense nuclear matter. To establish an understanding of the observed yields, a systematic study of high density baryon matter at different beam energies is essential. This might also reveal possible discontinuities in the energy dependence of the reaction mechanism. We present preliminary results for kaon production in Au+Au collisions at beam kinetic energies of 6, 8, and 10.7 GeV/u obtained by the E917 experiment at the AGS (BNL). These measurements complement those carried out by the E866 collaboration at 2, 4, and 10.7 GeV/u with a significantly enlarged data sample. In both experiments a large range of rapidities was covered by taking data at different angular settings of the magnetic spectrometer.

  6. High-density electroencephalography developmental neurophysiological trajectories.

    Science.gov (United States)

    Dan, Bernard; Pelc, Karine; Cebolla, Ana M; Cheron, Guy

    2015-04-01

    Efforts to document early changes in the developing brain have resulted in the construction of increasingly accurate structural images based on magnetic resonance imaging (MRI) in newborn infants. Tractography diagrams obtained through diffusion tensor imaging have focused on white matter microstructure, with particular emphasis on neuronal connectivity at the level of fibre tract systems. Electroencephalography (EEG) provides a complementary approach with more direct access to brain electrical activity. Its temporal resolution is excellent, and its spatial resolution can be enhanced to physiologically relevant levels, through the combination of high-density recordings (e.g. by using 64 channels in newborn infants) and mathematical models (e.g. inverse modelling computation), to identify generators of different oscillation bands and synchrony patterns. The integration of functional and structural topography of the neonatal brain provides insights into typical brain organization, and the deviations seen in particular contexts, for example the effect of hypoxic-ischaemic insult in terms of damage, eventual reorganization, and functional changes. Endophenotypes can then be used for pathophysiological reasoning, management planning, and outcome measurements, and allow a longitudinal approach to individual developmental trajectories. © The Authors. Journal compilation © 2015 Mac Keith Press.

  7. 14 CFR 93.123 - High density traffic airports.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 2 2010-01-01 2010-01-01 false High density traffic airports. 93.123... (CONTINUED) AIR TRAFFIC AND GENERAL OPERATING RULES SPECIAL AIR TRAFFIC RULES High Density Traffic Airports § 93.123 High density traffic airports. (a) Each of the following airports is designated as a...

  8. Investigation of the basic physics of high efficiency semiconductor hot carrier solar cell

    Science.gov (United States)

    Alfano, R. R.; Wang, W. B.; Mohaidat, J. M.; Cavicchia, M. A.; Raisky, O. Y.

    1995-01-01

    The main purpose of this research program is to investigate potential semiconductor materials and their multi-band-gap MQW (multiple quantum wells) structures for high efficiency solar cells for aerospace and commercial applications. The absorption and PL (photoluminescence) spectra, the carrier dynamics, and band structures have been investigated for semiconductors of InP, GaP, GaInP, and InGaAsP/InP MQW structures, and for semiconductors of GaAs and AlGaAs by previous measurements. The barrier potential design criteria for achieving maximum energy conversion efficiency, and the resonant tunneling time as a function of barrier width in high efficiency MQW solar cell structures have also been investigated in the first two years. Based on previous carrier dynamics measurements and the time-dependent short circuit current density calculations, an InAs/InGaAs - InGaAs/GaAs - GaAs/AlGaAs MQW solar cell structure with 15 bandgaps has been designed. The absorption and PL spectra in InGaAsP/InP bulk and MQW structures were measured at room temperature and 77 K with different pump wavelength and intensity, to search for resonant states that may affect the solar cell activities. Time-resolved IR absorption for InGaAsP/InP bulk and MQW structures has been measured by femtosecond visible-pump and IR-probe absorption spectroscopy. This, with the absorption and PL measurements, will be helpful to understand the basic physics and device performance in multi-bandgap InAs/InGaAs - InGaAs/InP - InP/InGaP MQW solar cells. In particular, the lifetime of the photoexcited hot electrons is an important parameter for the device operation of InGaAsP/InP MQW solar cells working in the resonant tunneling conditions. Lastly, time evolution of the hot electron relaxation in GaAs has been measured in the temperature range of 4 K through 288 K using femtosecond pump-IR-probe absorption technique. The temperature dependence of the hot electron relaxation time in the X valley has been measured.

  9. High-altitude atomic nitrogen densities

    Science.gov (United States)

    Oran, E. S.; Strobel, D. F.; Mauersberger, K.

    1978-01-01

    Theoretical calculations of the seasonal and diurnal variations of atomic nitrogen are compared with measurements made by the open source neutral mass spectrometer on the AE-C satellite. With the simultaneous measurements of molecular nitrogen and atomic oxygen densities as input, model calculations of odd nitrogen densities predict the same trends in atomic nitrogen as those observed. From these comparisons it is inferred that horizontal transport significantly reduces the diurnal variation of atomic nitrogen. Estimates are given of the sensitivity of atomic nitrogen densities to variations in the photoelectron flux, the neutral temperatures, and the neutral winds.

  10. Stability of low-carrier-density topological-insulator Bi{sub 2}Se{sub 3} thin films and effect of capping layers

    Energy Technology Data Exchange (ETDEWEB)

    Salehi, Maryam [Department of Materials Science and Engineering, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854 (United States); Brahlek, Matthew; Koirala, Nikesh; Moon, Jisoo; Oh, Seongshik, E-mail: ohsean@physics.rutgers.edu [Department of Physics and Astronomy, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854 (United States); Wu, Liang; Armitage, N. P. [Department of Physics and Astronomy, The Institute for Quantum Matter, The Johns Hopkins University, Baltimore, Maryland 21218 (United States)

    2015-09-01

    Although over the past number of years there have been many advances in the materials aspects of topological insulators (TIs), one of the ongoing challenges with these materials is the protection of them against aging. In particular, the recent development of low-carrier-density bulk-insulating Bi{sub 2}Se{sub 3} thin films and their sensitivity to air demands reliable capping layers to stabilize their electronic properties. Here, we study the stability of the low-carrier-density Bi{sub 2}Se{sub 3} thin films in air with and without various capping layers using DC and THz probes. Without any capping layers, the carrier density increases by ∼150% over a week and by ∼280% over 9 months. In situ-deposited Se and ex situ-deposited poly(methyl methacrylate) suppress the aging effect to ∼27% and ∼88%, respectively, over 9 months. The combination of effective capping layers and low-carrier-density TI films will open up new opportunities in topological insulators.

  11. Charge carrier density at the (Na/K)TaO{sub 3}/SrTiO{sub 3} interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Schwingenschloegl, Udo; Nazir, Safdar [KAUST, PSE Division, Thuwal 23955-6900, Kingdom of Saudi Arabia (Saudi Arabia)

    2012-07-01

    The formation of a quasi two-dimensional electron gas between the band insulators NaTaO{sub 3} and SrTiO{sub 3} as well as KTaO{sub 3} and SrTiO{sub 3} is studied by means of the full-potential linearized augmented plane-wave method of density functional theory. Optimization of the atomic positions points to only small changes in the chemical bonding at the interface. The creation of metallic interface states thus is not affected by structural relaxation but can be explained by charge transfer between transition metal and oxygen atoms. It is to be expected that a charge transfer is likewise important for related interfaces such as LaAlO{sub 3}/SrTiO{sub 3}. Both the p-type (NaO){sup -}/(TiO{sub 2}){sup 0} and n-type (TaO{sub 2}){sup +}/(SrO){sup 0} interfaces in NaTaO{sub 3}/SrTiO{sub 3} are found to be metallic with strongly enhanced charge carrier densities as compared to the respective interfaces in KTaO{sub 3}/SrTiO{sub 3}. The effects of O vacancies are discussed. Spin-polarized calculations point to the formation of isolated O 2p magnetic moments, located in the metallic region of the p-type interface. The systems under investigation are suitable for disentangling the complex behavior of metallic interface states, since the structural relaxation is small.

  12. Alternative Approaches to High Energy Density Fusion

    Science.gov (United States)

    Hammer, J.

    2016-10-01

    This paper explores selected approaches to High Energy Density (HED) fusion, beginning with discussion of ignition requirements at the National Ignition Facility (NIF). The needed improvements to achieve ignition are closely tied to the ability to concentrate energy in the implosion, manifested in the stagnation pressure, Pstag. The energy that must be assembled in the imploded state to ignite varies roughly as Pstag-2, so among other requirements, there is a premium on reaching higher Pstag to achieve ignition with the available laser energy. The U.S. inertial confinement fusion program (ICF) is pursuing higher Pstag on NIF through improvements to capsule stability and symmetry. One can argue that recent experiments place an approximate upper bound on the ultimate ignition energy requirement. Scaling the implosions consistently in spatial, temporal and energy scales shows that implosions of the demonstrated quality ignite robustly at 9-15 times the current energy of NIF. While lasers are unlikely to reach that bounding energy, it appears that pulsed-power sources could plausibly do so, giving a range of paths forward for ICF depending on success in improving energy concentration. In this paper, I show the scaling arguments then discuss topics from my own involvement in HED fusion. The recent Viewfactor experiments at NIF have shed light on both the observed capsule drive deficit and errors in the detailed modelling of hohlraums. The latter could be important factors in the inability to achieve the needed symmetry and energy concentration. The paper then recounts earlier work in Fast Ignition and the uses of pulsed-power for HED and fusion applications. It concludes with a description of a method for improving pulsed-power driven hohlraums that could potentially provide a factor of 10 in energy at NTF-like drive conditions and reach the energy bound for indirect drive ICF.

  13. High current density cathode for electrorefining in molten electrolyte

    Science.gov (United States)

    Li, Shelly X.

    2010-06-29

    A high current density cathode for electrorefining in a molten electrolyte for the continuous production and collection of loose dendritic or powdery deposits. The high current density cathode eliminates the requirement for mechanical scraping and electrochemical stripping of the deposits from the cathode in an anode/cathode module. The high current density cathode comprises a perforated electrical insulated material coating such that the current density is up to 3 A/cm.sup.2.

  14. Orbital quantization in the high-magnetic-field state of a charge-density-wave system

    Science.gov (United States)

    Andres, D.; Kartsovnik, M. V.; Grigoriev, P. D.; Biberacher, W.; Müller, H.

    2003-11-01

    A superposition of the Pauli and orbital couplings of a high magnetic field to charge carriers in a charge-density-wave (CDW) system is proposed to give rise to transitions between subphases with quantized values of the CDW wave vector. By contrast to the purely orbital field-induced density-wave effects which require a strongly imperfect nesting of the Fermi surface, the new transitions can occur even if the Fermi surface is well nested at zero field. We suggest that such transitions are observed in the organic metal α-(BEDT-TTF)2KHg(SCN)4 under a strongly tilted magnetic field.

  15. High Density Lipoprotein Metabolism in Man

    Science.gov (United States)

    Blum, Conrad B.; Levy, Robert I.; Eisenberg, Shlomo; Hall, Marshall; Goebel, Robert H.; Berman, Mones

    1977-01-01

    The turnover of 125I-high density lipoprotein (HDL) was examined in a total of 14 studies in eight normal volunteers in an attempt to determine the metabolic relationship between apolipoproteins A-I (apoA-I) and A-II (apoA-II) of HDL and to define further some of the determinants of HDL metabolism. All subjects were first studied under conditions of an isocaloric balanced diet (40% fat, 40% carbohydrate). Four were then studied with an 80% carbohydrate diet, and two were studied while receiving nicotinic acid (1 g three times daily) and ingesting the same isocaloric balanced diet. The decay of autologous 125I-HDL and the appearance of urinary radioactivity were followed for at least 2 wk in each study. ApoA-I and apoA-II were isolated by Sephadex G-200 chromatography from serial plasma samples in each study. The specific activities of these peptides were then measured directly. It was found that the decay of specific activity of apoA-I and apoA-II were parallel to one another in all studies. The mean half-life of the terminal portion of decay was 5.8 days during the studies with a balanced diet. Mathematical modeling of the decay of plasma radioactivity and appearance of urinary radioactivity was most consistent with a two-compartment model. One compartment is within the plasma and exchanges with a nonplasma component. Catabolism occurs from both of these compartments. With a balanced isocaloric diet, the mean synthetic rate for HDL protein was 8.51 mg/kg per day. HDL synthesis was not altered by the high carbohydrate diet and was only slightly decreased by nicotinic acid treatment. These perturbations had effects on HDL catabolic pathways that were reciprocal in many respects. With an 80% carbohydrate diet, the rate of catabolism from the plasma compartment rose by a mean of 39.1%; with nicotinic acid treatment, it fell by 42.2%. Changes in the rate of catabolism from the second compartment were generally opposite those in the rate of catabolism from the plasma

  16. Step-taper active-region quantum cascade lasers for carrier-leakage suppression and high internal differential efficiency

    Science.gov (United States)

    Kirch, J. D.; Chang, C.-C.; Boyle, C.; Mawst, L. J.; Lindberg, D.; Earles, T.; Botez, D.

    2016-03-01

    By stepwise tapering both the barrier heights and quantum-well depths in the active regions of 8.7 μm- and 8.4 μm-emitting quantum cascade lasers (QCLs) virtually complete carrier-leakage suppression is achieved, as evidenced by high values for both the threshold-current characteristic temperature coefficient T0 (283 K and 242 K) and the slope-efficiency characteristic temperature coefficient T1 (561 K and 279 K), over the 20-60 °C heatsink-temperature range, for low- and high-doped devices, respectively. Such high values are obtained while the threshold-current density is kept relatively low for 35-period, low- and high-doped devices: 1.58 kA/cm2 and 1.88 kA/cm2, respectively. In addition, due to resonant extraction from the lower laser level, high differential-transition-efficiency values (89-90%) are obtained. In turn, the slope-efficiency for 3 mm-long, 35-period high-reflectivity (HR)-coated devices are: 1.15-1.23 W/A; that is, 30- 40 % higher than for same-geometry and similar-doping conventional 8-9 μm-emitting QCLs. As a result of both efficient carrier-leakage suppression as well as fast and efficient carrier extraction, the values for the internal differential efficiency are found to be ≍ 86%, by comparison to typical values in the 58-67 % range for conventional QCLs emitting in the 7-11 μm wavelength range.

  17. Variable kernel density estimation in high-dimensional feature spaces

    CSIR Research Space (South Africa)

    Van der Walt, Christiaan M

    2017-02-01

    Full Text Available Estimating the joint probability density function of a dataset is a central task in many machine learning applications. In this work we address the fundamental problem of kernel bandwidth estimation for variable kernel density estimation in high...

  18. Observable to explore high density behaviour of symmetry energy

    CERN Document Server

    Sood, Aman D

    2011-01-01

    We aim to see the sensitivity of collective transverse in-plane flow to symmetry energy at low as well as high densities and also to see the effect of different density dependencies of symmetry energy on the same.

  19. Synchrotron radiation absorber for high density loads

    Science.gov (United States)

    Anashin, V. V.; Kuzminych, V. S.; Trakhtenberg, E. M.; Zholents, A. A.

    1991-10-01

    A design of a special synchrotron radiation absorber for the storage ring VEPP-4M is presented. The density of the synchrotron radiation power on the absorber surface is up to 500 W/mm 2. The absorber is made from a beryllium plate, brazed inside to the copper vacuum chamber, which is intensively water-cooled from outside.

  20. High density and high temperature plasmas in Large Helical Device

    Science.gov (United States)

    Komori, Akio

    2010-11-01

    Recently a new confinement regime called Super Dense Core (SDC) mode was discovered in Large Helical Device (LHD). An extremely high density core region with more than ~ 1 × 1021 m-3 is obtained with the formation of an Internal Diffusion Barrier (IDB). The density gradient at the IDB is very high and the particle confinement in the core region is ~ 0.2 s. It is expected, for the future reactor, that the IDB-SDC mode has a possibility to achieve the self-ignition condition with lower temperature than expected before. Conventional approaches to increase the temperature have also been tried in LHD. For the ion heating, the perpendicular neutral beam injection effectively increased the ion temperature up to 5.6 keV with the formation of the internal transport barrier (ITB). In the electron heating experiments with 77 GHz gyrotrons, the highest electron temperature more than 15 keV was achieved, where plasmas are in the neoclassical regime.

  1. High density and high temperature plasmas in Large Helical Device

    Energy Technology Data Exchange (ETDEWEB)

    Komori, Akio, E-mail: komori@LHD.nifs.ac.jp [National Institute for Fusion Science, 322-6 Oroshi, Toki, Gifu 509-5292 (Japan)

    2010-11-01

    Recently a new confinement regime called Super Dense Core (SDC) mode was discovered in Large Helical Device (LHD). An extremely high density core region with more than {approx} 1 x 10{sup 21} m{sup -3} is obtained with the formation of an Internal Diffusion Barrier (IDB). The density gradient at the IDB is very high and the particle confinement in the core region is {approx} 0.2 s. It is expected, for the future reactor, that the IDB-SDC mode has a possibility to achieve the self-ignition condition with lower temperature than expected before. Conventional approaches to increase the temperature have also been tried in LHD. For the ion heating, the perpendicular neutral beam injection effectively increased the ion temperature up to 5.6 keV with the formation of the internal transport barrier (ITB). In the electron heating experiments with 77 GHz gyrotrons, the highest electron temperature more than 15 keV was achieved, where plasmas are in the neoclassical regime.

  2. Highly Compressed Ion Beams for High Energy Density Science

    CERN Document Server

    Friedman, Alex; Briggs, Richard J; Callahan, Debra; Caporaso, George; Celata, C M; Davidson, Ronald C; Faltens, Andy; Grant-Logan, B; Grisham, Larry; Grote, D P; Henestroza, Enrique; Kaganovich, Igor D; Lee, Edward; Lee, Richard; Leitner, Matthaeus; Nelson, Scott D; Olson, Craig; Penn, Gregory; Reginato, Lou; Renk, Tim; Rose, David; Sessler, Andrew M; Staples, John W; Tabak, Max; Thoma, Carsten H; Waldron, William; Welch, Dale; Wurtele, Jonathan; Yu, Simon

    2005-01-01

    The Heavy Ion Fusion Virtual National Laboratory (HIF-VNL) is developing the intense ion beams needed to drive matter to the High Energy Density (HED) regimes required for Inertial Fusion Energy (IFE) and other applications. An interim goal is a facility for Warm Dense Matter (WDM) studies, wherein a target is heated volumetrically without being shocked, so that well-defined states of matter at 1 to 10 eV are generated within a diagnosable region. In the approach we are pursuing, low to medium mass ions with energies just above the Bragg peak are directed onto thin target "foils," which may in fact be foams or "steel wool" with mean densities 1% to 100% of solid. This approach complements that being pursued at GSI, wherein high-energy ion beams deposit a small fraction of their energy in a cylindrical target. We present the requirements for warm dense matter experiments, and describe suitable accelerator concepts, including novel broadband traveling wave pulse-line, drift-tube linac, RF, and single-gap approa...

  3. Development of high temperature superconductors having high critical current density

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Gye Wong; Kim, C. J.; Lee, H.G.; Kwon, S. C.; Lee, H. J.; Kim, K. B.; Park, J. Y.; Jung, C. H

    2000-08-01

    Fabrication of high T{sub c} superconductors and its applications for electric power device were carried out for developing superconductor application technologies. High quality YBCO superconductors was fabricated by melt texture growth, top-seeded melt growth process and multi-seeded melt growth process and the properties was compared. The critical current density of the melt processed YBCO superconductors was about few 10,000 A/cm{sup 2} and the levitation force was 50 N. The processing time needed for the growth of the 123 single grain was greatly reduced by applying multi-seeding without no significant degradation of the levitation force. The multi-seeded melt growth process was confirmed as a time-saving and cost-effective method for the fabrication of bulk superconductors with controlled crystallographic orientation.

  4. Sputtered thin films for high density tape recording

    NARCIS (Netherlands)

    Nguyen, L.T.

    This thesis describes the investigation of sputtered thin film media for high density tape recording. As discussed in Chapter 1, to meet the tremendous demand of data storage, the density of recording tape has to be increased continuously. For further increasing the bit density the key factors are:

  5. Sputtered thin films for high density tape recording

    NARCIS (Netherlands)

    Nguyen, L.T.

    2004-01-01

    This thesis describes the investigation of sputtered thin film media for high density tape recording. As discussed in Chapter 1, to meet the tremendous demand of data storage, the density of recording tape has to be increased continuously. For further increasing the bit density the key factors are:

  6. Charge transfer polarisation wave and carrier pairing in the high T(sub c) copper oxides

    Science.gov (United States)

    Chakraverty, B. K.

    1990-01-01

    The High T(sub c) oxides are highly polarizable materials and are charge transfer insulators. The charge transfer polarization wave formalism is developed in these oxides. The dispersion relationships due to long range dipole-dipole interaction of a charge transfer dipole lattice are obtained in 3-D and 2-D. These are high frequency bosons and their coupling with carriers is weak and antiadiabatic in nature. As a result, the mass renormalization of the carriers is negligible in complete contrast to conventional electron-phonon interaction, that give polarons and bipolarons. Both bound and superconducting pairing is discussed for a model Hamiltonian valid in the antiadiabatic regime, both in 3-D and 2-D. The stability of the charge transfer dipole lattice has interesting consequences that are discussed.

  7. Carrier behavior of HgTe under high pressure revealed by Hall effect measurement

    Institute of Scientific and Technical Information of China (English)

    胡廷静; 崔晓岩; 李雪飞; 王婧姝; 吕秀梅; 王棱升; 杨景海; 高春晓

    2015-01-01

    We investigate the carrier behavior of HgTe under high pressures up to 23 GPa using in situ Hall effect measurements. As the phase transitions from zinc blende to cinnabar, then to rock salt, and finally to Cmcm occur, all the parameters change discontinuously. The conductivity variation under compression is described by the carrier parameters. For the zinc blende phase, both the decrease of carrier concentration and the increase of mobility indicate the overlapped valence band and conduction band separates with pressure. Pressure causes an increase in the hole concentration of HgTe in the cinnabar phase, which leads to the carrier-type inversion and the lowest mobility at 5.6 GPa. In the phase transition process from zinc blende to rock salt, Te atoms are the major ones in atomic movements in the pressure regions of 1.0–1.5 GPa and 1.8–3.1 GPa, whereas Hg atoms are the major ones in the pressure regions of 1.5–1.8 GPa and 3.1–7.7 GPa. The polar optical scattering of the rock salt phase decreases with pressure.

  8. Tuning the carrier density of LaAlO3/SrTiO3 interfaces by capping La1-xSrxMnO3

    Science.gov (United States)

    Shi, Y. J.; Wang, S.; Zhou, Y.; Ding, H. F.; Wu, D.

    2013-02-01

    We present a systematical study on the electronic transport properties of the insulating LaAlO3 (3 unit cells)/SrTiO3 interfaces capping with thin layers of La1-xSrxMnO3, whose formal polarization is continually tuned by Sr doping. When the Sr doping is lower than 2/3, the LaAlO3/SrTiO3 interfaces show metallic behaviors. The carrier mobility is almost independent on the Sr doping for metallic interface, indicating that the capping layer does not change the density of the oxygen vacancies and the interface intermixing. However, the sheet carrier densities monotonically decrease as increasing Sr doping, which is ascribed to the decrease of the La1-xSrxMnO3 formal polarization. These results strongly support the intrinsic mechanism of the polar catastrophe model and provide a new approach to tailor the interface states of complex oxide heterostructures.

  9. Effects of low-temperature (120 °C) annealing on the carrier concentration and trap density in amorphous indium gallium zinc oxide thin film transistors

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jae-sung; Piao, Mingxing; Jang, Ho-Kyun; Kim, Gyu-Tae, E-mail: gtkim@korea.ac.kr [School of Electrical Engineering, Korea University, Seoul 136-701 (Korea, Republic of); Oh, Byung Su [School of Electrical Engineering, Korea University, Seoul 136-701 (Korea, Republic of); Samsung Display Company, Yongin (Korea, Republic of); Joo, Min-Kyu [School of Electrical Engineering, Korea University, Seoul 136-701 (Korea, Republic of); IMEP-LAHC, Grenoble INP, Minatec, CS 50257, 38016 Grenoble (France); Ahn, Seung-Eon [School of Electrical Engineering, Korea University, Seoul 136-701 (Korea, Republic of); Samsung Advanced Institute of Technology, Samsung Electronics Corporations, Yongin 446-712 (Korea, Republic of)

    2014-12-28

    We report an investigation of the effects of low-temperature annealing on the electrical properties of amorphous indium gallium zinc oxide (a-IGZO) thin-film transistors (TFTs). X-ray photoelectron spectroscopy was used to characterize the charge carrier concentration, which is related to the density of oxygen vacancies. The field-effect mobility was found to decrease as a function of the charge carrier concentration, owing to the presence of band-tail states. By employing the transmission line method, we show that the contact resistance did not significantly contribute to the changes in device performance after annealing. In addition, using low-frequency noise analyses, we found that the trap density decreased by a factor of 10 following annealing at 120 °C. The switching operation and on/off ratio of the a-IGZO TFTs improved considerably after low-temperature annealing.

  10. High power densities from high-temperature material interactions

    Energy Technology Data Exchange (ETDEWEB)

    Morris, J.F.

    1981-01-01

    Thermionic energy conversion (TEC) and metallic-fluid heat pipes (MFHPs) offer important and unique advantages in terrestrial and space energy processing. And they are well suited to serve together synergistically. TEC and MFHPs operate through working-fluid vaporization, condensation cycles that accept great thermal power densities at high temperatures. TEC and MFHPs have apparently simple, isolated performance mechanisms that are somewhat similar. And they also have obviously difficult, complected material problems that again are somewhat similar. Intensive investigation reveals that aspects of their operating cycles and material problems tend to merge: high-temperature material effects determine the level and lifetime of performance. Simplified equations verify the preceding statement for TEC and MFHPs. Material properties and interactions exert primary influences on operational effectiveness. And thermophysicochemical stabilities dictate operating temperatures which regulate the thermoemissive currents of TEC and the vaporization flow rates of MFHPs. Major high-temperature material problems of TEC and MFHPs have been solved. These solutions lead to productive, cost-effective applications of current TEC and MFHPs - and point to significant improvements with anticipated technological gains.

  11. Investigation of carrier density and mobility in microcrystalline silicon alloys using Hall effect and thermopower measurements; Untersuchung der Ladungstraegerkonzentration und -beweglichkeit in mikrokristallinen Siliziumlegierungen mit Hall-Effekt und Thermokraft

    Energy Technology Data Exchange (ETDEWEB)

    Sellmer, Christian

    2012-08-31

    The electronic properties of amorphous and microcrystalline silicon layers in thin-film solar cells significantly affect the efficiency of solar cells. An important property of the individual layer is the electronic transport, which is described by the variables conductivity, photoconductivity, mobility, and carrier concentration. In the past, individual characterization methods were typically used to determine the electronic properties. Using the combination of Hall effect, conductivity, and thermoelectric power measurements additional variables can be derived, such as the effective density of states at the valence and conduction band edge, making a more detailed description of the material possible. To systematically study the electronic properties - in particular carrier mobility and carrier concentration - various series of silicon films are prepared for this work including microcrystalline silicon layers of different doping and crystallinity and a series of silicon films where the Fermi level is moved by irradiation with high energy electrons on one and the same sample. The results show that the transition from amorphous to microcrystalline transport is relatively abrupt. If the electron transport takes place in only amorphous regions, it is marked by the sign anomaly of the Hall effect. If a continuous crystalline path exists, the electronic properties are dominated by the crystalline volume fraction. The results of the measurements of silicon layers are compared with those of microcrystalline silicon carbide samples. Silicon carbide is especially interesting for future applications in thin-film solar cells due to high transparency and high conductivity. It is shown that the effective density of states at the valence and conduction band edge as a function of temperature in p- and n-type microcrystalline silicon and silicon carbide samples largely coincide with those of crystalline silicon or silicon carbide. A square root shaped profile of the density of

  12. High Density Nano-Electrode Array for Radiation Detection

    Energy Technology Data Exchange (ETDEWEB)

    Mano Misra

    2010-05-07

    Bulk single crystals of Cd1-xZnxTe (x=0.04 to x=0.2) compound semiconductor is used for room temperature radiation detection. The production of large volume of Cd1-xZnxTe with low defect density is expensive. As a result there is a growing research interest in the production of nanostructured compound semiconductors such as Cd1-xZnxTe in an electrochemical route. In this investigation, Cd1-xZnxTe ternary compound semiconductor, referred as CZT, was electrodeposited in the form of nanowires onto a TiO2 nanotubular template from propylene carbonate as the non-aqueous electrolyte, using a pulse-reverse electrodeposition process at 130 ºC. The template acted as a support in growing ordered nanowire of CZT which acts as a one dimensional conductor. Cyclic Voltammogram (CV) studies were conducted in determining the potentials for the growth of nanowires of uniform stoichiometry. The morphologies and composition of CZT were characterized by using SEM, TEM and XRD. The STEM mapping carried out on the nanowires showed the uniform distribution of Cd, Zn and Te elements. TEM image showed that the nanowires were polycrystalline in nature. The Mott-Schottky analysis carried on the nanowires showed that the nanowires were a p-type semiconductor. The carrier density, band gap and resistivity of the Cd0.9Zn0.1Te nanowires were 4.29x1013 cm-3, 1.56 eV and 2.76x1011Ω-cm respectively. The high resistivity was attributed to the presence of deep defect states such as cadmium vacancies or Te antisites which were created by the anodic cycle of the pulse-reverse electrodeposition process. Stacks of series connected CZT nanowire arrays were tested with different bias potentials. The background current was in the order of tens of picoamperes. When exposed to radiation source Amerecium-241 (60 KeV, 4 μCi), the stacked CZT nanowires arrays showed sensing behavior. The sensitivity of the nanowire arrays increased as the number of stacks increased. The preliminary results indicate that the

  13. Method for producing high carrier concentration p-Type transparent conducting oxides

    Science.gov (United States)

    Li, Xiaonan; Yan, Yanfa; Coutts, Timothy J.; Gessert, Timothy A.; Dehart, Clay M.

    2009-04-14

    A method for producing transparent p-type conducting oxide films without co-doping plasma enhancement or high temperature comprising: a) introducing a dialkyl metal at ambient temperature and a saturated pressure in a carrier gas into a low pressure deposition chamber, and b) introducing NO alone or with an oxidizer into the chamber under an environment sufficient to produce a metal-rich condition to enable NO decomposition and atomic nitrogen incorporation into the formed transparent metal conducting oxide.

  14. Reliability of High I/O High Density CCGA Interconnect Electronic Packages under Extreme Thermal Environment

    Science.gov (United States)

    Ramesham, Rajeshuni

    2012-01-01

    This paper provides the experimental test results of advanced CCGA packages tested in extreme temperature thermal environments. Standard optical inspection and x-ray non-destructive inspection tools were used to assess the reliability of high density CCGA packages for deep space extreme temperature missions. Ceramic column grid array (CCGA) packages have been increasing in use based on their advantages such as high interconnect density, very good thermal and electrical performances, compatibility with standard surface-mount packaging assembly processes, and so on. CCGA packages are used in space applications such as in logic and microprocessor functions, telecommunications, payload electronics, and flight avionics. As these packages tend to have less solder joint strain relief than leaded packages or more strain relief over lead-less chip carrier packages, the reliability of CCGA packages is very important for short-term and long-term deep space missions. We have employed high density CCGA 1152 and 1272 daisy chained electronic packages in this preliminary reliability study. Each package is divided into several daisy-chained sections. The physical dimensions of CCGA1152 package is 35 mm x 35 mm with a 34 x 34 array of columns with a 1 mm pitch. The dimension of the CCGA1272 package is 37.5 mm x 37.5 mm with a 36 x 36 array with a 1 mm pitch. The columns are made up of 80% Pb/20%Sn material. CCGA interconnect electronic package printed wiring polyimide boards have been assembled and inspected using non-destructive x-ray imaging techniques. The assembled CCGA boards were subjected to extreme temperature thermal atmospheric cycling to assess their reliability for future deep space missions. The resistance of daisy-chained interconnect sections were monitored continuously during thermal cycling. This paper provides the experimental test results of advanced CCGA packages tested in extreme temperature thermal environments. Standard optical inspection and x-ray non

  15. Reliability of High I/O High Density CCGA Interconnect Electronic Packages under Extreme Thermal Environment

    Science.gov (United States)

    Ramesham, Rajeshuni

    2012-01-01

    This paper provides the experimental test results of advanced CCGA packages tested in extreme temperature thermal environments. Standard optical inspection and x-ray non-destructive inspection tools were used to assess the reliability of high density CCGA packages for deep space extreme temperature missions. Ceramic column grid array (CCGA) packages have been increasing in use based on their advantages such as high interconnect density, very good thermal and electrical performances, compatibility with standard surface-mount packaging assembly processes, and so on. CCGA packages are used in space applications such as in logic and microprocessor functions, telecommunications, payload electronics, and flight avionics. As these packages tend to have less solder joint strain relief than leaded packages or more strain relief over lead-less chip carrier packages, the reliability of CCGA packages is very important for short-term and long-term deep space missions. We have employed high density CCGA 1152 and 1272 daisy chained electronic packages in this preliminary reliability study. Each package is divided into several daisy-chained sections. The physical dimensions of CCGA1152 package is 35 mm x 35 mm with a 34 x 34 array of columns with a 1 mm pitch. The dimension of the CCGA1272 package is 37.5 mm x 37.5 mm with a 36 x 36 array with a 1 mm pitch. The columns are made up of 80% Pb/20%Sn material. CCGA interconnect electronic package printed wiring polyimide boards have been assembled and inspected using non-destructive x-ray imaging techniques. The assembled CCGA boards were subjected to extreme temperature thermal atmospheric cycling to assess their reliability for future deep space missions. The resistance of daisy-chained interconnect sections were monitored continuously during thermal cycling. This paper provides the experimental test results of advanced CCGA packages tested in extreme temperature thermal environments. Standard optical inspection and x-ray non

  16. High density semiconductor nanodots by direct laser fabrication

    Science.gov (United States)

    Haghizadeh, Anahita; Yang, Haeyeon

    2016-03-01

    We report a direct method of fabricating high density nanodots on the GaAs(001) surfaces using laser irradiations on the surface. Surface images indicate that the large clumps are not accompanied with the formation of nanodots even though its density is higher than the critical density above which detrimental large clumps begin to show up in the conventional Stranski-Krastanov growth technique. Atomic force microscopy is used to image the GaAs(001) surfaces that are irradiated by high power laser pulses interferentially. The analysis suggests that high density quantum dots be fabricated directly on semiconductor surfaces.

  17. Heat transfer in high density electronics packaging

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    In order to get an insight into the thermal characteristic and to evaluate the thermal reliability of the "System in Packaging"(SIP), a new solution of electronics packaging, a heat transfer model of SIP was developed to predict the heat dissipation capacity and to investigate the effect of different factors on the temperature distribution in the electronics. The affecting parameters under consideration include the thermophysical properties of the substrates, the coefficient of convection heat transfer, the thickness of the chip, and the density of power dissipation. ALGOR, a kind of finite element analysis software,was used to do the model simulation. Based on the sinulation and analysis of the heat conduction and convection resistance, criteria for the thermal design were established and possible measurement for enhancing power dissipation was provided, The results show that the heat transfer model provides a new and effective way to the thermal design and thermal analysis of SIP and to the mechanical analysis for the further investigation of SIP.

  18. Enhanced terahertz radiation from high stacking fault density nonpolar GaN

    Science.gov (United States)

    Metcalfe, Grace D.; Shen, Hongen; Wraback, Michael; Hirai, Asako; Wu, Feng; Speck, James S.

    2008-06-01

    Terahertz emission from high stacking fault density m-GaN has been observed using ultrafast pulse excitation. The terahertz signal exhibits a 360° periodicity with sample rotation and a polarity flip at 180°, characteristic of real carrier transport in an in-plane electric field parallel to the c axis induced by stacking fault (SF)-terminated internal polarization at wurtzite domain boundaries. The terahertz emission can be enhanced by several times relative to that from a SF-free m-GaN sample, for which the terahertz signal emanates from surface surge currents and diffusion-driven carrier transport normal to the surface and is independent of the c-axis orientation.

  19. MAC Support for High Density Wireless Sensor Networks

    NARCIS (Netherlands)

    Taddia, C.; Meratnia, Nirvana; van Hoesel, L.F.W.; Mazzini, G.; Havinga, Paul J.M.

    Large scale and high density networks of tiny sensor nodes offer promising solutions for event detection and actuating applications. In this paper we address the effect of high density of wireless sensor network performance with a specific MAC protocol, the Lightweight Medium Access Control (LMAC).

  20. High-density carbon ablator ignition path with low-density gas-filled rugby hohlraum

    Science.gov (United States)

    Amendt, Peter; Ho, Darwin D.; Jones, Ogden S.

    2015-04-01

    A recent low gas-fill density (0.6 mg/cc 4He) cylindrical hohlraum experiment on the National Ignition Facility has shown high laser-coupling efficiency (>96%), reduced phenomenological laser drive corrections, and improved high-density carbon capsule implosion symmetry [Jones et al., Bull. Am. Phys. Soc. 59(15), 66 (2014)]. In this Letter, an ignition design using a large rugby-shaped hohlraum [Amendt et al., Phys. Plasmas 21, 112703 (2014)] for high energetics efficiency and symmetry control with the same low gas-fill density (0.6 mg/cc 4He) is developed as a potentially robust platform for demonstrating thermonuclear burn. The companion high-density carbon capsule for this hohlraum design is driven by an adiabat-shaped [Betti et al., Phys. Plasmas 9, 2277 (2002)] 4-shock drive profile for robust high gain (>10) 1-D ignition performance and large margin to 2-D perturbation growth.

  1. High-density carbon ablator ignition path with low-density gas-filled rugby hohlraum

    Energy Technology Data Exchange (ETDEWEB)

    Amendt, Peter; Ho, Darwin D.; Jones, Ogden S. [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States)

    2015-04-15

    A recent low gas-fill density (0.6 mg/cc {sup 4}He) cylindrical hohlraum experiment on the National Ignition Facility has shown high laser-coupling efficiency (>96%), reduced phenomenological laser drive corrections, and improved high-density carbon capsule implosion symmetry [Jones et al., Bull. Am. Phys. Soc. 59(15), 66 (2014)]. In this Letter, an ignition design using a large rugby-shaped hohlraum [Amendt et al., Phys. Plasmas 21, 112703 (2014)] for high energetics efficiency and symmetry control with the same low gas-fill density (0.6 mg/cc {sup 4}He) is developed as a potentially robust platform for demonstrating thermonuclear burn. The companion high-density carbon capsule for this hohlraum design is driven by an adiabat-shaped [Betti et al., Phys. Plasmas 9, 2277 (2002)] 4-shock drive profile for robust high gain (>10) 1-D ignition performance and large margin to 2-D perturbation growth.

  2. Quantum Phenomena in High Energy Density Plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Murnane, Margaret [Univ. of Colorado, Boulder, CO (United States); Kapteyn, Henry [Univ. of Colorado, Boulder, CO (United States)

    2017-05-10

    The possibility of implementing efficient (phase matched) HHG upconversion of deep- UV lasers in multiply-ionized plasmas, with potentially unprecedented conversion efficiency is a fascinating prospect. HHG results from the extreme nonlinear response of matter to intense laser light:high harmonics are radiated as a result of a quantum coherent electron recollision process that occurs during laser field ionization of an atom. Under current support from this grant in work published in Science in 2015, we discovered a new regime of bright HHG in highly-ionized plasmas driven by intense UV lasers, that generates bright harmonics to photon energies >280eV

  3. Carrier-density dependence of photoluminescence from localized states in InGaN/GaN quantum wells in nanocolumns and a thin film

    Energy Technology Data Exchange (ETDEWEB)

    Shimosako, N., E-mail: n-shimosako@sophia.jp; Inose, Y.; Satoh, H.; Kinjo, K.; Nakaoka, T.; Oto, T. [Department of Engineering and Applied Sciences, Sophia University, 7-1 Kioi-cho, Chiyoda-ku, Tokyo 102-8554 (Japan); Kishino, K.; Ema, K. [Department of Engineering and Applied Sciences, Sophia University, 7-1 Kioi-cho, Chiyoda-ku, Tokyo 102-8554 (Japan); Sophia Nanotechnology Research Center, Sophia University, 7-1 Kioi-cho, Chiyoda-ku, Tokyo 102-8554 (Japan)

    2015-11-07

    We have measured and analyzed the carrier-density dependence of photoluminescence (PL) spectra and the PL efficiency of InGaN/GaN multiple quantum wells in nanocolumns and in a thin film over a wide excitation range. The localized states parameters, such as the tailing parameter, density and size of the localized states, and the mobility edge density are estimated. The spectral change and reduction of PL efficiency are explained by filling of the localized states and population into the extended states around the mobility edge density. We have also found that the nanocolumns have a narrower distribution of the localized states and a higher PL efficiency than those of the film sample although the In composition of the nanocolumns is higher than that of the film.

  4. Strontium Insertion in Methylammonium Lead Iodide: Long Charge Carrier Lifetime and High Fill-Factor Solar Cells

    Energy Technology Data Exchange (ETDEWEB)

    Pérez-del-Rey, Daniel [Instituto de Ciencia Molecular, Universidad de Valencia, C/J. Beltran 2 46980 Paterna Spain; Forgács, Dávid [Instituto de Ciencia Molecular, Universidad de Valencia, C/J. Beltran 2 46980 Paterna Spain; Hutter, Eline M. [Department of Chemical Engineering, Delft University of Technology, Van der Maasweg 9 2629 HZ Delft The Netherlands; Savenije, Tom J. [Department of Chemical Engineering, Delft University of Technology, Van der Maasweg 9 2629 HZ Delft The Netherlands; Nordlund, Dennis [Stanford Linear Accelerator Campus, Stanford Synchrotron Laboratory, Menlo Park CA 94025 USA; Schulz, Philip [National Center for Photovoltaics, National Renewable Energy Laboratory, 15013 Denver West Parkway Golden CO 80401 USA; Berry, Joseph J. [National Center for Photovoltaics, National Renewable Energy Laboratory, 15013 Denver West Parkway Golden CO 80401 USA; Sessolo, Michele [Instituto de Ciencia Molecular, Universidad de Valencia, C/J. Beltran 2 46980 Paterna Spain; Bolink, Henk J. [Instituto de Ciencia Molecular, Universidad de Valencia, C/J. Beltran 2 46980 Paterna Spain

    2016-09-22

    The addition of Sr2+ in CH3NH3PbI3 perovskite films enhances the charge carrier collection efficiency of solar cells leading to very high fill factors, up to 85%. The charge carrier lifetime of Sr2+-containing perovskites is in excess of 40 us, longer than those reported for perovskite single crystals.

  5. Application of a high density adsorbent in expanded bed adsorption ...

    African Journals Online (AJOL)

    PRECIOUS

    2010-01-11

    Jan 11, 2010 ... The high density of the adsorbent allowed the EBA to be operated at linear velocity as high as 657 cm/h ... through precipitation and even dialyzed before sample ... In EBA process, upward fluidized stationary phase with.

  6. Carrier-wave Rabi-flopping signatures in high-order harmonic generation for alkali atoms.

    Science.gov (United States)

    Ciappina, M F; Pérez-Hernández, J A; Landsman, A S; Zimmermann, T; Lewenstein, M; Roso, L; Krausz, F

    2015-04-10

    We present a theoretical investigation of carrier-wave Rabi flopping in real atoms by employing numerical simulations of high-order harmonic generation (HHG) in alkali species. Given the short HHG cutoff, related to the low saturation intensity, we concentrate on the features of the third harmonic of sodium (Na) and potassium (K) atoms. For pulse areas of 2π and Na atoms, a characteristic unique peak appears, which, after analyzing the ground state population, we correlate with the conventional Rabi flopping. On the other hand, for larger pulse areas, carrier-wave Rabi flopping occurs, and is associated with a more complex structure in the third harmonic. These characteristics observed in K atoms indicate the breakdown of the area theorem, as was already demonstrated under similar circumstances in narrow band gap semiconductors.

  7. Carrier-wave Rabi flopping signatures in high-order harmonic generation for alkali atoms

    CERN Document Server

    Ciappina, M F; Landsman, A S; Zimmermann, T; Lewenstein, M; Roso, L; Krausz, F

    2015-01-01

    We present the first theoretical investigation of carrier-wave Rabi flopping in real atoms by employing numerical simulations of high-order harmonic generation (HHG) in alkali species. Given the short HHG cutoff, related to the low saturation intensity, we concentrate on the features of the third harmonic of sodium (Na) and potassium (K) atoms. For pulse areas of 2$\\pi$ and Na atoms, a characteristic unique peak appears, which, after analyzing the ground state population, we correlate with the conventional Rabi flopping. On the other hand, for larger pulse areas, carrier-wave Rabi flopping occurs, and is associated with a more complex structure in the third harmonic. These new characteristics observed in K atoms indicate the breakdown of the area theorem, as was already demonstrated under similar circumstances in narrow band gap semiconductors.

  8. Response of thermosphere density to high-latitude forcing

    Science.gov (United States)

    Yamazaki, Y.; Kosch, M. J.; Vickers, H.; Sutton, E. K.; Ogawa, Y.

    2014-12-01

    Solar wind-magnetospheric disturbances cause enhancements in the energy input to the high-latitude upper atmosphere through particle precipitation and Joule heating. As the upper atmosphere is heated and expanded during geomagnetically disturbed periods, the neutral density in the thermosphere increases at a fixed altitude. Conversely, the thermosphere contracts during the recovery phase of the disturbance, resulting in a decrease of the density. The main objectives of this study are (1) to determine the morphology of the global thermospheric density response to high-latitude forcing, and (2) to determine the recovery speed of the thermosphere density after geomagnetic disturbances. For (1), we use thermospheric density data measured by the Challenging Minisatellite Payload (CHAMP) satellite during 2000-2010. It is demonstrated that the density enhancement during disturbed periods occurs first in the dayside cusp region, and the density at other regions slowly follows it. The reverse process is observed when geomagnetic activity ceases; the density enhancement in the cusp region fades away first, then the global density slowly goes back to the quiet level. For (2), we analyze EISCAT Svalbard radar and Tromso UHF radar data to estimate thermospheric densities during the recovery phase of geomagnetic disturbances. We attempt to determine the time constant for the density recovery both inside and outside the cusp region.

  9. Nuclear Level Density at High Spin and Excitation Energy

    Institute of Scientific and Technical Information of China (English)

    A.N. Behkami; Z. Kargar

    2001-01-01

    The intensive studies of equilibrium processes in heavy-ion reaction have produced a need for information on nuclear level densities at high energies and spins. The Fermi gas level density is often used in investigation of heavy-ion reaction studies. Some papers have claimed that nuclear level densities might deviate substantially from the Fermi gas predications at excitations related to heavy-ion reactions. The formulae of calculation of the nuclear level density based on the theory of superconductivity are presented, special attention is paid to the dependence of the level density on the angular momentum. The spin-dependent nuclear level density is evaluated using the pairing interaction. The resulting level density for an average spin of 52h is evaluated for 155Er and compared with experimental data. Excellent agreement between experiment and theory is obtained.``

  10. Breast density estimation from high spectral and spatial resolution MRI.

    Science.gov (United States)

    Li, Hui; Weiss, William A; Medved, Milica; Abe, Hiroyuki; Newstead, Gillian M; Karczmar, Gregory S; Giger, Maryellen L

    2016-10-01

    A three-dimensional breast density estimation method is presented for high spectral and spatial resolution (HiSS) MR imaging. Twenty-two patients were recruited (under an Institutional Review Board--approved Health Insurance Portability and Accountability Act-compliant protocol) for high-risk breast cancer screening. Each patient received standard-of-care clinical digital x-ray mammograms and MR scans, as well as HiSS scans. The algorithm for breast density estimation includes breast mask generating, breast skin removal, and breast percentage density calculation. The inter- and intra-user variabilities of the HiSS-based density estimation were determined using correlation analysis and limits of agreement. Correlation analysis was also performed between the HiSS-based density estimation and radiologists' breast imaging-reporting and data system (BI-RADS) density ratings. A correlation coefficient of 0.91 ([Formula: see text]) was obtained between left and right breast density estimations. An interclass correlation coefficient of 0.99 ([Formula: see text]) indicated high reliability for the inter-user variability of the HiSS-based breast density estimations. A moderate correlation coefficient of 0.55 ([Formula: see text]) was observed between HiSS-based breast density estimations and radiologists' BI-RADS. In summary, an objective density estimation method using HiSS spectral data from breast MRI was developed. The high reproducibility with low inter- and low intra-user variabilities shown in this preliminary study suggest that such a HiSS-based density metric may be potentially beneficial in programs requiring breast density such as in breast cancer risk assessment and monitoring effects of therapy.

  11. A simple approach for producing highly efficient DNA carriers with reduced toxicity based on modified polyallylamine

    Energy Technology Data Exchange (ETDEWEB)

    Oskuee, Reza Kazemi [Neurogenic Inflammation Research Center, Mashhad University of Medical Sciences, Mashhad (Iran, Islamic Republic of); Department of Medical Biotechnology, School of Medicine, Mashhad University of Medical Sciences, Mashhad (Iran, Islamic Republic of); Dosti, Fatemeh [School of Pharmacy, Mashhad University of Medical Sciences, Mashhad (Iran, Islamic Republic of); Gholami, Leila [Targeted Drug Delivery Research Center, School of Medicine, Mashhad University of Medical Sciences, Mashhad (Iran, Islamic Republic of); Malaekeh-Nikouei, Bizhan, E-mail: malaekehb@mums.ac.ir [Nanotechnology Research Center, School of Pharmacy, Mashhad University of Medical Sciences, Mashhad (Iran, Islamic Republic of)

    2015-04-01

    Nowadays gene delivery is a topic in many research studies. Non-viral vectors have many advantages over viral vectors in terms of safety, immunogenicity and gene carrying capacity but they suffer from low transfection efficiency and high toxicity. In this study, polyallylamine (PAA), the cationic polymer, has been modified with hydrophobic branches to increase the transfection efficiency of the polymer. Polyallylamine with molecular weights of 15 and 65 kDa was selected and grafted with butyl, hexyl and decyl acrylate at percentages of 10, 30 and 50. The ability of the modified polymer to condense DNA was examined by ethidium bromide test. The complex of modified polymer and DNA (polyplex) was characterized for size, zeta potential, transfection efficiency and cytotoxicity in Neuro2A cell lines. The results of ethidium bromide test showed that grafting of PAA decreased its ability for DNA condensation but vectors could still condense DNA at moderate and high carrier to DNA ratios. Most of polyplexes had particle size between 150 and 250 nm. The prepared vectors mainly showed positive zeta potential but carriers composed of PAA with high percentage of grafting had negative zeta potential. The best transfection activity was observed in vectors with hexyl acrylate chain. Grafting of polymer reduced its cytotoxicity especially at percentages of 30 and 50. The vectors based of PAA 15 kDa had better transfection efficiency than the vectors made of PAA 65 kDa. In conclusion, results of the present study indicated that grafting PAA 15 kDa with high percentages of hexyl acrylate can help to prepare vectors with better transfection efficiency and less cytotoxicity. - Highlights: • The modified polyallylamine was synthesized as a gene carrier. • Modification of polyallylamine (15 kDa) with high percentages of hexyl acrylate improved transfection activity remarkably. • Grafting of polymer with acrylate derivatives reduced polymer cytotoxicity especially at percentages of

  12. Ultra high energy density and fast discharge nanocomposite capacitors

    Science.gov (United States)

    Tang, Haixiong; Sodano, Henry A.

    2013-04-01

    Nanocomposites containing high dielectric permittivity ceramics embedded in high breakdown strength polymers are currently of considerable interest as a solution for the development of high energy density capacitors. However, the improvement of dielectric permittivity comes at expense of the breakdown strength leading to limit the final energy density. Here, an ultra-high energy density nanocomposite was fabricated based on high aspect ratio barium strontium titanate nanowires. The pyroelectric phase Ba0.2Sr0.8TiO3 was chosen for the nanowires combined with quenched PVDF to fabricate high energy density nanocomposite. The energy density with 7.5% Ba0.2Sr0.8TiO3 nanowires reached 14.86 J/cc at 450 MV/m, which represented a 42.9% increase in comparison to the PVDF with an energy density of 10.4 J/cc at the same electric field. The capacitors have 1138% greater than higher energy density than commercial biaxial oriented polypropylene capacitors (1.2 J/cc at 640). These results demonstrate that the high aspect ratio nanowires can be used to produce nanocomposite capacitors with greater performance than the neat polymers thus providing a novel process for the development of future pulsed-power capacitors.

  13. Carrier Density and Compensation in Semiconductors with Multi Dopants and Multi Transition Energy Levels: The Case of Cu Impurity in CdTe: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Wei, S. H.; Ma, J.; Gessert, T. A.; Chin, K. K.

    2011-07-01

    Doping is one of the most important issues in semiconductor physics. The charge carrier generated by doping can profoundly change the properties of semiconductors and their performance in optoelectronic device applications, such as solar cells. Using detailed balance theory and first-principles calculated defect formation energies and transition energy levels, we derive general formulae to calculate carrier density for semiconductors with multi dopants and multi transition energy levels. As an example, we studied CdTe doped with Cu, in which VCd, CuCd, and Cui are the dominant defects/impurities. We show that in this system, when Cu concentration increases, the doping properties of the system can change from a poor p-type, to a poorer p-type, to a better p-type, and then to a poor p-type again, in good agreement with experimental observation of CdTe-based solar cells.

  14. Extraction of high charge density of states in electrolyte-gated polymer thin-film transistor with temperature-dependent measurements

    Science.gov (United States)

    Lee, Jiyoul

    2016-05-01

    Using temperature-dependent charge transport measurements, we investigated spectral density of states (DOS) in the bandgap of polythiophene thin-films under high carrier densities (Meyer-Neldel rule. The spectral DOS extracted from the electrolyte-gated polymer film lie in the range of 8.0 × 1019 cm-3 eV-1-8.0 × 1021 cm-3 eV-1, which are at least two orders of magnitude larger than the DOS extracted from the same polymer film at relatively low induced carrier densities by general oxide dielectrics.

  15. Supramolecular Aggregate as a High-Efficiency Gene Carrier Mediated with Optimized Assembly Structure.

    Science.gov (United States)

    Zhang, Yi; Duan, Junkun; Cai, Lingguang; Ma, Dong; Xue, Wei

    2016-11-02

    For cancer gene therapy, a safe and high-efficient gene carrier is a must. To resolve the contradiction between gene transfection efficiency and cytotoxicity, many polymers with complex topological structures have been synthesized, although their synthesis processes and structure control are difficult as well as the high molecular weight also bring high cytotoxicity. We proposed an alternative strategy that uses supramolecular inclusion to construct the aggregate from the small molecules for gene delivery, and to further explore the relationship between the topological assembly structure and their ability to deliver gene. Herein, PEI-1.8k-conjugating β-CD through 6-hydroxyl (PEI-6-CD) and 2-hydroxyl (PEI-2-CD) have been synthesized respectively and then assembled with diferrocene (Fc)-ended polyethylene glycol (PEG-Fc). The obtained aggregates were then used to deliver MMP-9 shRNA plasmid for MCF-7 cancer therapy. It was found that the higher gene transfection efficiency can be obtained by selecting PEI-2-CD as the host and tuning the host/guest molar ratios. With the rational modulation of supramolecular architectures, the aggregate played the functions similar to macromolecules which exhibit higher transfection efficiency than PEI-25k, but show much lower cytotoxicity because of the nature of small/low molecules. In vitro and in vivo assays confirmed that the aggregate could deliver MMP-9 shRNA plasmid effectively into MCF-7 cells and then downregulate MMP-9 expression, which induced the significant MCF-7 cell apoptosis, as well inhibit MCF-7 tumor growth with low toxicity. The supramolecular aggregates maybe become a promising carrier for cancer gene therapy and also provided an alternative strategy for designing new gene carriers.

  16. High resistivity and ultrafast carrier lifetime in argon implanted GaAs

    Energy Technology Data Exchange (ETDEWEB)

    Walukiewicz, W.; Liliental-Weber, Z.; Jasinski, J. [Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Almonte, M.; Prasad, A.; Haller, E.E.; Weber, E.R. [Lawrence Berkeley National Laboratory and University of California, Berkeley, California 94720 (United States); Grenier, P.; Whitaker, J.F. [Center for Ultrafast Optical Science, University of Michigan, Ann Arbor, Michigan 48109 (United States)

    1996-10-01

    We have investigated the optoelectronic and structural properties of GaAs that has been implanted with Ar ions and subsequently annealed. The material exhibits all the basic optical and electronic characteristics typically observed in nonstoichiometric, As implanted or low-temperature-grown GaAs. Annealing of Ar implanted GaAs at 600{degree}C produces a highly resistive material with a subpicosecond trapping lifetime for photoexcited carriers. Transmission electron microscopy shows that, instead of As precipitates, characteristic for the nonstoichiometeric GaAs, voids ranging in size from 3 to 5 nm are observed in Ar implanted and annealed GaAs. {copyright} {ital 1996 American Institute of Physics.}

  17. Nodal quasi-particles of the high-Tc superconductors as carriers of heat

    Directory of Open Access Journals (Sweden)

    K. Behnia

    2006-09-01

    Full Text Available   In the quest for understanding correlated electrons, high-temperature superconductivity remains a formidable challenge and a source of insight. This paper briefly recalls the central achievement by the study of heat transport at low temperatures. At very low temperatures, nodal quasi-particles of the d-wave superconducting gap become the main carriers of heat. Their thermal conductivity is unaffected by disorder and reflects the fine structure of the superconducting gap. This finding had led to new openings in the exploration of other unconventional superconductors

  18. Demonstration of high-speed multi-user multi-carrier CDMA visible light communication

    Science.gov (United States)

    Yang, Chao; Wang, Yuanquan; Wang, Yiguang; Huang, Xingxing; Chi, Nan

    2015-02-01

    We experimentally demonstrated a high-speed multi-user multi-carrier code-division multiple access (MC-CDMA) visible light communication (VLC) system. By employing a commercially available red light emitting diode (LED) and an avalanche photo diode (APD), we achieved a 16-user VLC system enabled by MC-CDMA, pre- and post-equalization, with an overall bit rate of 750 Mb/s over 1.5 m free-space transmission. The measured bit error ratio (BER) of each user is below the 7% pre-forward-error-correction (pre-FEC) threshold of 3.8×10-3.

  19. 128x128 Ultra-High Density Optical Interconnect Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Future NASA programs like Tertiary Planet Finder (TPF) require high-density deformable mirrors with up to 16,000 actuators to enable direct imaging of planets around...

  20. 128x128 Ultra-High Density Optical Interconnect Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Future NASA programs like Tertiary Planet Finder (TPF) require high density deformable mirrors with upto 16,000 actuators to enable direct imaging of planets around...

  1. High current density nanofilament cathodes for microwave amplifiers

    NARCIS (Netherlands)

    Schnell, J-P.; Minoux, E.; Gangloff, L.; Vincent, P.; Legagneux, P.; Dieumegard, D.; David, J.-F.; Peauger, F.; Hudanski, L.; Teo, K.B.K.; Lacerda, R.; Chhowalla, M.; Hasko, D.G.; Ahmed, H.; Amaratunga, G.A.J.; Milne, W.I.; Vila, L.; Dauginet-De Pra, L.; Demoustier-Champagne, S.; Ferain, E.; Legras, R.; Piraux, L.; Gröening, O.; Raedt, H. De; Michielsen, K.

    2004-01-01

    We study high current density nanofilament cathodes for microwave amplifiers. Two different types of aligned nanofilament array have been studied: first, metallic nanowires grown by electrodeposition into nanoporous templates at very low temperature (T

  2. High energy density nanocomposite capacitors using non-ferroelectric nanowires

    Science.gov (United States)

    Tang, Haixiong; Sodano, Henry A.

    2013-02-01

    A high energy density nanocomposite capacitor is fabricated by incorporating high aspect ratio functionalized TiO2 nanowires (NWs) into a polyvinylidene-fluoride matrix. These nanocomposites exhibited energy density as high as 12.4 J/cc at 450 MV/m, which is nine times larger than commercial biaxially oriented polypropylene polypropylene capacitors (1.2 J/cc at 640 MV/m). Also, the power density can reach 1.77 MW/cc with a discharge speed of 2.89 μs. The results presented here demonstrate that nanowires can be used to develop nanocomposite capacitors with high energy density and fast discharge speed for future pulsed-power applications.

  3. The usefulness of total cholesterol and high density lipoprotein ...

    African Journals Online (AJOL)

    The usefulness of total cholesterol and high density lipoprotein - cholesterol ratio in ... cholesterol and/or highdensity lipoprotein cholesterol/total cholesterol ratios in the interpretation of lipid profile result in clinical practice. ... Article Metrics.

  4. Spontaneous magnetization in high-density quark matter

    DEFF Research Database (Denmark)

    Tsue, Yasuhiko; da Providência, João; Providência, Constanca;

    2015-01-01

    It is shown that spontaneous magnetization occurs due to the anomalous magnetic moments of quarks in high-density quark matter under the tensor-type four-point interaction. The spin polarized condensate for each flavor of quark appears at high baryon density, which leads to the spontaneous...... magnetization due to the anomalous magnetic moments of quarks. The implications for the strong magnetic field in compact stars is discussed....

  5. Workshop on extremely high energy density plasmas and their diagnostics

    Energy Technology Data Exchange (ETDEWEB)

    Ishii, Shozo (ed.)

    2001-09-01

    Compiled are the papers presented at the workshop on 'Extremely High Energy Density Plasmas and Their Diagnostics' held at National Institute for Fusion Science. The papers cover physics and applications of extremely high-energy density plasmas such as dense z-pinch, plasma focus, and intense pulsed charged beams. Separate abstracts were presented for 7 of the papers in this report. The remaining 25 were considered outside the subject scope of INIS. (author)

  6. Fifth International Conference on High Energy Density Physics

    Energy Technology Data Exchange (ETDEWEB)

    Beg, Farhat

    2017-07-05

    The Fifth International Conference on High Energy Density Physics (ICHED 2015) was held in the Catamaran Hotel in San Diego from August 23-27, 2015. This meeting was the fifth in a series which began in 2008 in conjunction with the April meeting of the American Physical Society (APS). The main goal of this conference has been to bring together researchers from all fields of High Energy Density Science (HEDS) into one, unified meeting.

  7. Enhanced carrier collection efficiency in hierarchical nano-electrode for a high-performance photoelectrochemical cell

    Science.gov (United States)

    Hien, Truong Thi; Van Lam, Do; Kim, Chunjoong; Vuong, Nguyen Minh; Quang, Nguyen Duc; Kim, Dahye; Chinh, Nguyen Duc; Hieu, Nguyen Minh; Lee, Seung-Mo; Kim, Dojin

    2016-12-01

    The photoelectrochemical properties of CdS-sensitized ZnO nanorods grown on Pt-coated WO3 nanoplates are investigated to evaluate their effectiveness in hydrogen production. WO3 nanonanoplates are synthesized on glass substrates, followed by atomic layer deposition of Pt thin films as the terminal electrode to efficiently collect the photo-carriers generated from the ZnO/CdS absorption layers. Optimization of the fabrication process for the 3D hierarchical structure is performed, and the morphology and its effect on the photoelectrochemical performance of the electrodes are carefully studied using scanning electron microscopy, x-ray diffraction, and measurements of the photocurrent density and photo-conversion efficiencies. The enhanced PEC performance is elucidated by the 3D hierarchical geometry of the electrode. The optimized electrode shows a photocurrent density of ∼ 13 mA cm-2 and a conversion efficiency of ∼8.0% at -0.83 V (vs. SCE) in 0.5 M Na2S solution under the illumination of simulated solar light.

  8. Fabrication of very high density fuel pellets of thorium dioxide

    Science.gov (United States)

    Shiratori, Tetsuo; Fukuda, Kosaku

    1993-06-01

    Very high density ThO 2 pellets were prepared without binders and lubricants from the ThO 2 powder originated by the thorium oxalate, which was aimed to simplify the fabrication process by skipping a preheat treatment. The as-received ThO 2 powder with a surface area of 4.56 m 2/g was ball-milled up to about 9 m 2/g in order to increase the green pellet density as high as possible. Both of the single-sided and the double-sided pressing were tested in the range from 2 to 5 t/cm 2 in the green pellet formation. Sintering temperature was such low as 1550°C. The pellet prepared in this experiment had a very high density in the range from about 96 to 98% TD without any cracks, in which a difference of the pellet density was not recognized in the single-sided pressing methods.

  9. High-density scintillating glasses for a proton imaging detector

    Science.gov (United States)

    Tillman, I. J.; Dettmann, M. A.; Herrig, V.; Thune, Z. L.; Zieser, A. J.; Michalek, S. F.; Been, M. O.; Martinez-Szewczyk, M. M.; Koster, H. J.; Wilkinson, C. J.; Kielty, M. W.; Jacobsohn, L. G.; Akgun, U.

    2017-06-01

    High-density scintillating glasses are proposed for a novel proton-imaging device that can improve the accuracy of the hadron therapy. High-density scintillating glasses are needed to build a cost effective, compact calorimeter that can be attached to a gantry. This report summarizes the study on Europium, Terbium, and Cerium-doped scintillating glasses that were developed containing heavy elements such as Lanthanum, Gadolinium, and Tungsten. The density of the samples reach up to 5.9 g/cm3, and their 300-600 nm emission overlaps perfectly with the peak cathode sensitivity of the commercial photo detectors. The developed glasses do not require any special quenching and can be poured easily, which makes them a good candidate for production in various geometries. Here, the glass making conditions, preliminary tests on optical and physical properties of these scintillating, high-density, oxide glasses developed for a novel medical imaging application are reported.

  10. Stability of high cell density brewery fermentations during serial repitching.

    Science.gov (United States)

    Verbelen, Pieter J; Dekoninck, Tinne M L; Van Mulders, Sebastiaan E; Saerens, Sofie M G; Delvaux, Filip; Delvaux, Freddy R

    2009-11-01

    The volumetric productivity of the beer fermentation process can be increased by using a higher pitching rate (i.e. higher inoculum size). However, the decreased yeast net growth observed in these high cell density brewery fermentations can adversely affect the physiological stability throughout subsequent yeast generations. Therefore, different O(2) conditions (wort aeration and yeast preoxygenation) were applied to high cell density fermentation and eight generations of fermentations were evaluated together with conventional fermentations. Freshly propagated high cell density populations adapted faster to the fermentative conditions than normal cell density populations. Preoxygenating the yeast was essential for the yeast physiological and beer flavor compound stability of high cell density fermentations during serial repitching. In contrast, the use of non-preoxygenated yeast resulted in inadequate growth which caused (1) insufficient yield of biomass to repitch all eight generations, (2) a 10% decrease in viability, (3) a moderate increase of yeast age, (4) and a dramatic increase of the unwanted flavor compounds acetaldehyde and total diacetyl during the sequence of fermentations. Therefore, to achieve sustainable high cell density fermentations throughout the economical valuable process of serial repitching, adequate yeast growth is essential.

  11. High current density stability of ohmic contacts to silicon carbide

    Science.gov (United States)

    Downey, Brian P.

    The materials properties of SiC, such as wide bandgap, high breakdown electric field, and good thermal conductivity, make it an appealing option for high temperature and high power applications. The replacement of Si devices with SiC components could lead to a reduction in device size, weight, complexity, and cooling requirements along with an increase in device efficiency. One area of concern under high temperature or high current operation is the stability of the ohmic contacts. Ohmic contact degradation can cause an increase in parasitic resistance, which can diminish device performance. While contact studies have primarily focused on the high temperature stability of ohmic contacts to SiC, different failure mechanisms may arise under high current density stressing due to the influence of electromigration. In addition, preferential degradation may occur at the anode or cathode due to the directionality of current flow, known as a polarity effect. The failure mechanisms of ohmic contacts to p-type SiC under high current density stressing are explored. Complementary materials characterization techniques were used to analyze contact degradation, particularly the use of cross-sections prepared by focused ion beam for imaging using field emission scanning electron microscopy and elemental analysis using Auger electron spectroscopy. Initially the degradation of commonly studied Ni and Al-based contacts was investigated under continuous DC current. The contact metallization included a bond pad consisting of a TiW diffusion barrier and thick Au overlayer. The Ni contacts were found to degrade due to the growth of voids within the ohmic contact layer, which were initially produced during the high temperature Ni/SiC ohmic contact anneal. The Al-based contacts degraded due to the movement of Al from the ohmic contact layer to the surface of the Au bond pad, and the movement of Au into the ohmic contact layer from the bond pad. The inequality of Al and Au fluxes generated

  12. Beyond high-density lipoprotein cholesterol levels evaluating high-density lipoprotein function as influenced by novel therapeutic approaches

    National Research Council Canada - National Science Library

    deGoma, Emil M; deGoma, Rolando L; Rader, Daniel J

    2008-01-01

    A number of therapeutic strategies targeting high-density lipoprotein (HDL) cholesterol and reverse cholesterol transport are being developed to halt the progression of atherosclerosis or even induce regression...

  13. Comparison of low density and high density pedicle screw instrumentation in Lenke 1 adolescent idiopathic scoliosis.

    Science.gov (United States)

    Shen, Mingkui; Jiang, Honghui; Luo, Ming; Wang, Wengang; Li, Ning; Wang, Lulu; Xia, Lei

    2017-08-02

    The correlation between implant density and deformity correction has not yet led to a precise conclusion in adolescent idiopathic scoliosis (AIS). The aim of this study was to evaluate the effects of low density (LD) and high density (HD) pedicle screw instrumentation in terms of the clinical, radiological and Scoliosis Research Society (SRS)-22 outcomes in Lenke 1 AIS. We retrospectively reviewed 62 consecutive Lenke 1 AIS patients who underwent posterior spinal arthrodesis using all-pedicle screw instrumentation with a minimum follow-up of 24 months. The implant density was defined as the number of screws per spinal level fused. Patients were then divided into two groups according to the average implant density for the entire study. The LD group (n = 28) had fewer than 1.61 screws per level, while the HD group (n = 34) had more than 1.61 screws per level. The radiographs were analysed preoperatively, postoperatively and at final follow-up. The perioperative and SRS-22 outcomes were also assessed. Independent sample t tests were used between the two groups. Comparisons between the two groups showed no significant differences in the correction of the main thoracic curve and thoracic kyphosis, blood transfusion, hospital stay, and SRS-22 scores. Compared with the HD group, there was a decreased operating time (278.4 vs. 331.0 min, p = 0.004) and decreased blood loss (823.6 vs. 1010.9 ml, p = 0.048), pedicle screws needed (15.1 vs. 19.6, p density and high density pedicle screw instrumentation achieved satisfactory deformity correction in Lenke 1 AIS patients. However, the operating time and blood loss were reduced, and the implant costs were decreased with the use of low screw density constructs.

  14. High dislocation density of tin induced by electric current

    Energy Technology Data Exchange (ETDEWEB)

    Liao, Yi-Han; Liang, Chien-Lung; Lin, Kwang-Lung, E-mail: matkllin@mail.ncku.edu.tw [Department of Material Science and Engineering, National Cheng Kung University, Tainan 70101, Taiwan, R. O. C (China); Wu, Albert T. [Department of Chemical and Material Engineering, National Central University, Jhongli 32001, Taiwan, R. O. C (China)

    2015-12-15

    A dislocation density of as high as 10{sup 17} /m{sup 2} in a tin strip, as revealed by high resolution transmission electron microscope, was induced by current stressing at 6.5 x 10{sup 3} A/ cm{sup 2}. The dislocations exist in terms of dislocation line, dislocation loop, and dislocation aggregates. Electron Backscattered Diffraction images reflect that the high dislocation density induced the formation of low deflection angle subgrains, high deflection angle Widmanstätten grains, and recrystallization. The recrystallization gave rise to grain refining.

  15. Power-efficient high-speed parallel-sampling adcs for broadband multi-carrier systems

    CERN Document Server

    Lin, Yu; Doris, Kostas; van Roermund, Arthur H M

    2015-01-01

    This book addresses the challenges of designing high performance analog-to-digital converters (ADCs) based on the “smart data converters” concept, which implies context awareness, on-chip intelligence and adaptation. Readers will learn to exploit various information either a-priori or a-posteriori (obtained from devices, signals, applications or the ambient situations, etc.) for circuit and architecture optimization during the design phase or adaptation during operation, to enhance data converters performance, flexibility, robustness and power-efficiency. The authors focus on exploiting the a-priori knowledge of the system/application to develop enhancement techniques for ADCs, with particular emphasis on improving the power efficiency of high-speed and high-resolution ADCs for broadband multi-carrier systems.

  16. Hall effect in the low charge-carrier density ferromagnet UCo{sub 0.5}Sb{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Tran, V.H.; Troc, R.; Bukowski, Z. [W. Trzebiatowski Institute for Low Temperature and Structure Research, Polish Academy of Sciences, P.O. Box 1410, 50-950 Wroclaw (Poland); Paschen, S.; Steglich, F. [Max-Planck Institut fuer Chemische Physik fester Stoffe, 01187 Dresden (Germany)

    2006-01-01

    The Hall coefficient R {sub H} of ferromagnetic UCo{sub 0.5}Sb{sub 2} (T {sub C}=64.5 K) has been measured on a single crystal in the temperature range 2-300 K and in magnetic fields up to 7 T. The values of the normal R{sub 0} and anomalous R{sub s} coefficients were estimated by comparing R{sub H}(B) with magnetisation M (B) data. The charge carrier concentration is found to decrease rapidly when the system undergoes a transition to the ferromagnetic ordered state. The charge mobility appears to fall down by as much as two orders of magnitude for temperatures from 20 K to 2 K. We ascribe this behaviour to an enormous decrease of the carrier collision time. The temperature dependencies of the Hall mean free path and mobility can be consistently interpreted within the 2D-weak localization feature. (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  17. Noise reduction in muon tomography for detecting high density objects

    CERN Document Server

    Benettoni, M; Bonomi, G; Calvagno, G; Calvini, P; Checchia, P; Cortelazzo, G; Cossutta, L; Donzella, A; Furlan, M; Gonella, F; Pegoraro, M; Garola, A Rigoni; Ronchese, P; Squarcia, S; Subieta, M; Vanini, S; Viesti, G; Zanuttigh, P; Zenoni, A; Zumerle, G

    2013-01-01

    The muon tomography technique, based on multiple Coulomb scattering of cosmic ray muons, has been proposed as a tool to detect the presence of high density objects inside closed volumes. A new and innovative method is presented in this paper to handle the density fluctuations (noise) of reconstructed images, that are a known problem of this technique. The effectiveness of our method is evaluated using experimental data obtained with a muon tomography prototype located at Legnaro National Laboratories (LNL) of the Istituto Nazionale di Fisica Nucleare (INFN). The results reported in this paper, obtained with real cosmic ray data, show that with appropriate image filtering and muon momentum classification, the muon tomography technique can detect in short times high density materials, such as lead, when surrounded by light or medium density material. A comparison with algorithms published in literature is also presented.

  18. Noise reduction in muon tomography for detecting high density objects

    Science.gov (United States)

    Benettoni, M.; Bettella, G.; Bonomi, G.; Calvagno, G.; Calvini, P.; Checchia, P.; Cortelazzo, G.; Cossutta, L.; Donzella, A.; Furlan, M.; Gonella, F.; Pegoraro, M.; Rigoni Garola, A.; Ronchese, P.; Squarcia, S.; Subieta, M.; Vanini, S.; Viesti, G.; Zanuttigh, P.; Zenoni, A.; Zumerle, G.

    2013-12-01

    The muon tomography technique, based on multiple Coulomb scattering of cosmic ray muons, has been proposed as a tool to detect the presence of high density objects inside closed volumes. In this paper a new and innovative method is presented to handle the density fluctuations (noise) of reconstructed images, a well known problem of this technique. The effectiveness of our method is evaluated using experimental data obtained with a muon tomography prototype located at the Legnaro National Laboratories (LNL) of the Istituto Nazionale di Fisica Nucleare (INFN). The results reported in this paper, obtained with real cosmic ray data, show that with appropriate image filtering and muon momentum classification, the muon tomography technique can detect high density materials, such as lead, albeit surrounded by light or medium density material, in short times. A comparison with algorithms published in literature is also presented.

  19. High energy density interpenetrating networks from ionic networks and silicone

    DEFF Research Database (Denmark)

    Yu, Liyun; Madsen, Frederikke Bahrt; Hvilsted, Søren

    2015-01-01

    The energy density of dielectric elastomers (DEs) is sought increased for better exploitation of the DE technology since an increased energy density means that the driving voltage for a certain strain can be lowered in actuation mode or alternatively that more energy can be harvested in generator...... mode. One way to increase the energy density is to increase dielectric permittivity of the elastomer. A novel silicone elastomer system with high dielectric permittivity was prepared through the development of interpenetrating networks from ionically assembled silicone polymers and covalently...

  20. Solid Oxide Electrolysis Cells: Degradation at High Current Densities

    DEFF Research Database (Denmark)

    Knibbe, Ruth; Traulsen, Marie Lund; Hauch, Anne;

    2010-01-01

    The degradation of Ni/yttria-stabilized zirconia (YSZ)-based solid oxide electrolysis cells operated at high current densities was studied. The degradation was examined at 850°C, at current densities of −1.0, −1.5, and −2.0 A/cm2, with a 50:50 (H2O:H2) gas supplied to the Ni/YSZ hydrogen electrode...

  1. BCS Theory of Hadronic Matter at High Densities

    DEFF Research Database (Denmark)

    Bohr, Henrik; Panda, Prafulla K.; Providencia, Constanca

    2012-01-01

    The equilibrium between the so-called 2SC and CFL phases of strange quark matter at high densities is investigated in the framework of a simple schematic model of the NJL type. Equal densities are assumed for quarks u, d and s. The 2SC phase is here described by a color-flavor symmetric state...... than is usual in NJL type models. This should be adequate if the relevant chemical potential does not exceed 0.6 GeV....

  2. Highly efficient low color temperature organic LED using blend carrier modulation layer

    Science.gov (United States)

    Hsieh, Yao-Ching; Chen, Szu-Hao; Shen, Shih-Ming; Wang, Ching-Chiun; Chen, Chien-Chih; Jou, Jwo-Huei

    2012-10-01

    Color temperature (CT) of light has great effect on human physiology and psychology, and low CT light, minimizing melatonin suppression and decreasing the risk of breast, colorectal, and prostate cancer. We demonstrates the incorporation of a blend carrier modulation interlayer (CML) between emissive layers to improve the device performance of low CT organic light emitting diodes, which exhibits an external quantum efficiency of 22.7% and 36 lm W-1 (54 cd A-1) with 1880 K at 100 cd m-2, or 20.8% and 29 lm W-1 (50 cd A-1) with 1940 K at 1000 cd m-2. The result shows a CT much lower than that of incandescent bulbs, which is 2500 K with 15 lmW-1 efficiency, and even as low as that of candles, which is 2000 K with 0.1 lmW-1. The high efficiency of the proposed device may be attributed to its CML, which helps effectively distribute the entering carriers into the available recombination zones.

  3. Mendelian Disorders of High-Density Lipoprotein Metabolism

    NARCIS (Netherlands)

    Oldoni, Federico; Sinke, Richard J.; Kuivenhoven, Jan Albert

    2014-01-01

    High-density lipoproteins (HDLs) are a highly heterogeneous and dynamic group of the smallest and densest lipoproteins present in the circulation. This review provides the current molecular insight into HDL metabolism led by articles describing mutations in genes that have a large affect on HDL chol

  4. Quark matter at high density based on an extended confined isospin-density-dependent mass model

    Science.gov (United States)

    Qauli, A. I.; Sulaksono, A.

    2016-01-01

    We investigate the effect of the inclusion of relativistic Coulomb terms in a confined-isospin-density-dependent-mass (CIDDM) model of strange quark matter (SQM). We found that if we include the Coulomb term in scalar density form, the SQM equation of state (EOS) at high densities is stiffer but if we include the Coulomb term in vector density form it is softer than that of the standard CIDDM model. We also investigate systematically the role of each term of the extended CIDDM model. Compared with what was reported by Chu and Chen [Astrophys. J. 780, 135 (2014)], we found the stiffness of SQM EOS is controlled by the interplay among the oscillator harmonic, isospin asymmetry and Coulomb contributions depending on the parameter's range of these terms. We have found that the absolute stable condition of SQM and the mass of 2 M⊙ pulsars can constrain the parameter of oscillator harmonic κ1≈0.53 in the case the Coulomb term is excluded. If the Coulomb term is included, for the models with their parameters are consistent with SQM absolute stability condition, the 2.0 M⊙ constraint more prefers the maximum mass prediction of the model with the scalar Coulomb term than that of the model with the vector Coulomb term. On the contrary, the high densities EOS predicted by the model with the vector Coulomb is more compatible with the recent perturbative quantum chromodynamics result [1] than that predicted by the model with the scalar Coulomb. Furthermore, we also observed the quark composition in a very high density region depends quite sensitively on the kind of Coulomb term used.

  5. High-density turbidity currents: Are they sandy debris flows?

    Energy Technology Data Exchange (ETDEWEB)

    Shanmugam, G. [Mobil Exploration and Producing Technical Center, Dallas, TX (United States)

    1996-01-01

    Conventionally, turbidity currents are considered as fluidal flows in which sediment is supported by fluid turbulence, whereas debris flows are plastic flows in which sediment is supported by matrix strength, dispersive pressure, and buoyant lift. The concept of high-density turbidity current refers to high-concentration, commonly non-turbulent, flows of fluids in which sediment is supported mainly by matrix strength, dispersive pressure, and buoyant lift. The conventional wisdom that traction carpets with entrained turbulent clouds on top represent high-density turbidity currents is a misnomer because traction carpets are neither fluidal nor turbulent. Debris flows may also have entrained turbulent clouds on top. The traction carpet/debris flow and the overriding turbulent clouds are two separate entities in terms of flow rheology and sediment-support mechanism. In experimental and theoretical studies, which has linked massive sands and floating clasts to high-density turbidity currents, the term high-density turbidity current has actually been used for laminar flows. In alleviating this conceptual problem, sandy debris flow is suggested as a substitute for high-density turbidity current. Sandy debris flows represent a continuous spectrum of processes between cohesive and cohesionless debris flows. Commonly they are rheologically plastic. They may occur with or without entrained turbulent clouds on top. Their sediment-support mechanisms include matrix strength, dispersive pressure, and buoyant lift. They are characterized by laminar flow conditions, a moderate to high grain concentration, and a low to moderate mud content. Although flows evolve and transform during the course of transport in density-stratified flows, the preserved features in a deposit are useful to decipher only the final stages of deposition. At present, there are no established criteria to decipher transport mechanism from the depositional record.

  6. High density data storage principle, technology, and materials

    CERN Document Server

    Zhu, Daoben

    2009-01-01

    The explosive increase in information and the miniaturization of electronic devices demand new recording technologies and materials that combine high density, fast response, long retention time and rewriting capability. As predicted, the current silicon-based computer circuits are reaching their physical limits. Further miniaturization of the electronic components and increase in data storage density are vital for the next generation of IT equipment such as ultra high-speed mobile computing, communication devices and sophisticated sensors. This original book presents a comprehensive introduction to the significant research achievements on high-density data storage from the aspects of recording mechanisms, materials and fabrication technologies, which are promising for overcoming the physical limits of current data storage systems. The book serves as an useful guide for the development of optimized materials, technologies and device structures for future information storage, and will lead readers to the fascin...

  7. Nonlinear dielectric thin films for high-power electric storage with energy density comparable with electrochemical supercapacitors.

    Science.gov (United States)

    Yao, Kui; Chen, Shuting; Rahimabady, Mojtaba; Mirshekarloo, Meysam Sharifzadeh; Yu, Shuhui; Tay, Francis Eng Hock; Sritharan, Thirumany; Lu, Li

    2011-09-01

    Although batteries possess high energy storage density, their output power is limited by the slow movement of charge carriers, and thus capacitors are often required to deliver high power output. Dielectric capacitors have high power density with fast discharge rate, but their energy density is typically much lower than electrochemical supercapacitors. Increasing the energy density of dielectric materials is highly desired to extend their applications in many emerging power system applications. In this paper, we review the mechanisms and major characteristics of electric energy storage with electrochemical supercapacitors and dielectric capacitors. Three types of in-house-produced ferroic nonlinear dielectric thin film materials with high energy density are described, including (Pb(0.97)La(0.02))(Zr(0.90)Sn(0.05)Ti(0.05))O(3) (PLZST) antiferroelectric ceramic thin films, Pb(Zn(1/3)Nb(2/3))O(3-)Pb(Mg(1/3)Nb(2/3))O(3-)PbTiO(3) (PZN-PMN-PT) relaxor ferroelectric ceramic thin films, and poly(vinylidene fluoride) (PVDF)-based polymer blend thin films. The results showed that these thin film materials are promising for electric storage with outstandingly high power density and fairly high energy density, comparable with electrochemical supercapacitors.

  8. Modeling particle-laden turbulent flows with two-way coupling using a high-order kernel density function method

    Science.gov (United States)

    Smith, Timothy; Lu, Xiaoyi; Ranjan, Reetesh; Pantano, Carlos

    2016-11-01

    We describe a two-way coupled turbulent dispersed flow computational model using a high-order kernel density function (KDF) method. The carrier-phase solution is obtained using a high-order spatial and temporal incompressible Navier-Stokes solver while the KDF dispersed-phase solver uses the high-order Legendre WENO method. The computational approach is used to model carrier-phase turbulence modulation by the dispersed phase, and particle dispersion by turbulence as a function of momentum coupling strength (particle loading) and number of KDF basis functions. The use of several KDF's allows the model to capture statistical effects of particle trajectory crossing to high degree. Details of the numerical implementation and the coupling between the incompressible flow and dispersed-phase solvers will be discussed, and results at a range of Reynolds numbers will be presented. This work was supported by the National Science Foundation under Grant DMS-1318161.

  9. Frontiers for Discovery in High Energy Density Physics

    Energy Technology Data Exchange (ETDEWEB)

    Davidson, R. C.; Katsouleas, T.; Arons, J.; Baring, M.; Deeney, C.; Di Mauro, L.; Ditmire, T.; Falcone, R.; Hammer, D.; Hill, W.; Jacak, B.; Joshi, C.; Lamb, F.; Lee, R.; Logan, B. G.; Melissinos, A.; Meyerhofer, D.; Mori, W.; Murnane, M.; Remington, B.; Rosner, R.; Schneider, D.; Silvera, I.; Stone, J.; Wilde, B.; Zajc. W.

    2004-07-20

    The report is intended to identify the compelling research opportunities of high intellectual value in high energy density physics. The opportunities for discovery include the broad scope of this highly interdisciplinary field that spans a wide range of physics areas including plasma physics, laser and particle beam physics, nuclear physics, astrophysics, atomic and molecular physics, materials science and condensed matter physics, intense radiation-matter interaction physics, fluid dynamics, and magnetohydrodynamics

  10. Manipulation of magnetic carriers for drug delivery using pulsed-current high T {sub c} superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Cha, Yung [Energy Technology Division and Material Science Division, Building 335, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439 (United States)]. E-mail: yscha@anl.gov; Chen, Lihua [Energy Technology Division and Material Science Division, Building 335, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439 (United States); Department of Electrical and Computer Engineering, Michigan State University, East Lansing, MI 48824 (United States); Askew, Thomas [Energy Technology Division and Material Science Division, Building 335, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439 (United States); Physics Department, Kalamazoo College, Kalamazoo, MI 49006 (United States); Veal, Boyd [Energy Technology Division and Material Science Division, Building 335, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439 (United States); Hull, John [Energy Technology Division and Material Science Division, Building 335, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439 (United States)

    2007-04-15

    An innovative method of manipulating magnetic carriers is proposed, and its feasibility for drug delivery and therapy is demonstrated experimentally. The proposed method employs pulsed-field solenoid coils with high-critical- temperature (T {sub c}) superconductor inserts. Pulsed current is used to magnetize and de-magnetize the superconductor insert. The proposed method was demonstrated to be able to (1) move magnetic particles, ranging in size from a few millimeters to 10 {mu}m, with strong enough forces over a substantial distance, (2) hold the particles at a designated position as long as needed, and (3) reverse the processes and retrieve the particles. We further demonstrated that magnetic particles can be manipulated in a stationary environment, in water flow, and in simulated blood (water/glycerol mixture) flow.

  11. Manipulation of magnetic carriers for drug delivery using pulsed-current high Tc superconductors

    Science.gov (United States)

    Cha, Yung; Chen, Lihua; Askew, Thomas; Veal, Boyd; Hull, John

    2007-04-01

    An innovative method of manipulating magnetic carriers is proposed, and its feasibility for drug delivery and therapy is demonstrated experimentally. The proposed method employs pulsed-field solenoid coils with high-critical- temperature ( Tc) superconductor inserts. Pulsed current is used to magnetize and de-magnetize the superconductor insert. The proposed method was demonstrated to be able to (1) move magnetic particles, ranging in size from a few millimeters to 10 μm, with strong enough forces over a substantial distance, (2) hold the particles at a designated position as long as needed, and (3) reverse the processes and retrieve the particles. We further demonstrated that magnetic particles can be manipulated in a stationary environment, in water flow, and in simulated blood (water/glycerol mixture) flow.

  12. Single Carrier Architecture for High Data Rate Wireless PAN Communications System

    CERN Document Server

    Rakotondrainibe, Lahatra; Zaharia, Gheorghe; Grunfelder, Guy; Zein, Ghaïs El

    2010-01-01

    A 60 GHz wireless Gigabit Ethernet (G.E.) communication system is developed at IETR. As the 60 GHz radio link operates only in a single-room configuration, an additional Radio over Fibre (RoF) link is used to ensure the communications in all the rooms of a residential environment. The realized system covers 2 GHz bandwidth. Due to the hardware constraints, a symbol rate at 875 Mbps is attained using simple single carrier architecture. In the baseband (BB) processing block, an original byte/frame synchronization process is designed to provide a smaller value of the preamble missing detection and false alarm probabilities. Bit error rate (BER) measurements have been realized in a large gym for line-of-sight (LOS) conditions. A Tx-Rx distance greater than 30 meters was attained with low BER using high gain antennas and forward error correction RS (255, 239) coding.

  13. A high carrier injection terahertz quantum cascade laser based on indirectly pumped scheme

    Energy Technology Data Exchange (ETDEWEB)

    Razavipour, S. G., E-mail: sgrazavi@uwaterloo.ca; Xu, C.; Wasilewski, Z. R.; Ban, D. [Department of Electrical and Computer Engineering, Waterloo Institute for Nanotechnology, University of Waterloo, 200 University Ave. W., Waterloo, Ontario N2L3G1 (Canada); Dupont, E.; Laframboise, S. R. [National Research Council, Blg. M-50, 1200 Montreal Rd., Ottawa, Ontario K1A0R6 (Canada); Chan, C. W. I.; Hu, Q. [Department of Electrical Engineering and Computer Science, Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)

    2014-01-27

    A Terahertz quantum cascade laser with a rather high injection coupling strength based on an indirectly pumped scheme is designed and experimentally implemented. To effectively suppress leakage current, the chosen quantum cascade module of the device is based on a five-well GaAs/Al{sub 0.25}Ga{sub 0.75}As structure. The device lases up to 151 K with a lasing frequency of 2.67 THz. This study shows that the effect of higher energy states in carrier transport and the long-range tunnel coupling between states that belong to non-neighbouring modules have to be considered in quantum design of structures with a narrow injector barrier. Moreover, the effect of interface roughness scattering between the lasing states on threshold current is crucial.

  14. Interplay between hopping and band transport in high-mobility disordered semiconductors at large carrier concentrations: The case of the amorphous oxide InGaZnO

    Science.gov (United States)

    Fishchuk, I. I.; Kadashchuk, A.; Bhoolokam, A.; de Jamblinne de Meux, A.; Pourtois, G.; Gavrilyuk, M. M.; Köhler, A.; Bässler, H.; Heremans, P.; Genoe, J.

    2016-05-01

    We suggest an analytic theory based on the effective medium approximation (EMA) which is able to describe charge-carrier transport in a disordered semiconductor with a significant degree of degeneration realized at high carrier concentrations, especially relevant in some thin-film transistors (TFTs), when the Fermi level is very close to the conduction-band edge. The EMA model is based on special averaging of the Fermi-Dirac carrier distributions using a suitably normalized cumulative density-of-state distribution that includes both delocalized states and the localized states. The principal advantage of the present model is its ability to describe universally effective drift and Hall mobility in heterogeneous materials as a function of disorder, temperature, and carrier concentration within the same theoretical formalism. It also bridges a gap between hopping and bandlike transport in an energetically heterogeneous system. The key assumption of the model is that the charge carriers move through delocalized states and that, in addition to the tail of the localized states, the disorder can give rise to spatial energy variation of the transport-band edge being described by a Gaussian distribution. It can explain a puzzling observation of activated and carrier-concentration-dependent Hall mobility in a disordered system featuring an ideal Hall effect. The present model has been successfully applied to describe experimental results on the charge transport measured in an amorphous oxide semiconductor, In-Ga-Zn-O (a-IGZO). In particular, the model reproduces well both the conventional Meyer-Neldel (MN) compensation behavior for the charge-carrier mobility and inverse-MN effect for the conductivity observed in the same a-IGZO TFT. The model was further supported by ab initio calculations revealing that the amorphization of IGZO gives rise to variation of the conduction-band edge rather than to the creation of localized states. The obtained changes agree with the one we

  15. Study of Volumetrically Heated Ultra-High Energy Density Plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Rocca, Jorge J. [Colorado State Univ., Fort Collins, CO (United States)

    2016-10-27

    Heating dense matter to millions of degrees is important for applications, but requires complex and expensive methods. The major goal of the project was to demonstrate using a compact laser the creation of a new ultra-high energy density plasma regime characterized by simultaneous extremely high temperature and high density, and to study it combining experimental measurements and advanced simulations. We have demonstrated that trapping of intense femtosecond laser pulses deep within ordered nanowire arrays can heat near solid density matter into a new ultra hot plasma regime. Extreme electron densities, and temperatures of several tens of million degrees were achieved using laser pulses of only 0.5 J energy from a compact laser. Our x-ray spectra and simulations showed that extremely highly ionized plasma volumes several micrometers in depth are generated by irradiation of gold and Nickel nanowire arrays with femtosecond laser pulses of relativistic intensities. We obtained extraordinarily high degrees of ionization (e.g. we peeled 52 electrons from gold atoms, and up to 26 electrons from nickel atoms). In the process we generated Gigabar pressures only exceeded in the central hot spot of highly compressed thermonuclear fusion plasmas.. The plasma created after the dissolved wires expand, collide, and thermalize, is computed to have a thermal energy density of 0.3 GJ cm-3 and a pressure of 1-2 Gigabar. These are pressures only exceeded in highly compressed thermonuclear fusion plasmas. Scaling these results to higher laser intensities promises to create plasmas with temperatures and pressures exceeding those in the center of the sun.

  16. High density operation for reactor-relevant power exhaust

    Science.gov (United States)

    Wischmeier, M.

    2015-08-01

    With increasing size of a tokamak device and associated fusion power gain an increasing power flux density towards the divertor needs to be handled. A solution for handling this power flux is crucial for a safe and economic operation. Using purely geometric arguments in an ITER-like divertor this power flux can be reduced by approximately a factor 100. Based on a conservative extrapolation of current technology for an integrated engineering approach to remove power deposited on plasma facing components a further reduction of the power flux density via volumetric processes in the plasma by up to a factor of 50 is required. Our current ability to interpret existing power exhaust scenarios using numerical transport codes is analyzed and an operational scenario as a potential solution for ITER like divertors under high density and highly radiating reactor-relevant conditions is presented. Alternative concepts for risk mitigation as well as strategies for moving forward are outlined.

  17. Origins and Impacts of High-Density Symmetry Energy

    CERN Document Server

    Li, Bao-An

    2016-01-01

    What is nuclear symmetry energy? Why is it important? What do we know about it? Why is it so uncertain especially at high densities? Can the total symmetry energy or its kinetic part be negative? What are the effects of three-body and/or tensor force on symmetry energy? How can we probe the density dependence of nuclear symmetry energy with terrestrial nuclear experiments? What observables of heavy-ion reactions are sensitive to the high-density behavior of nuclear symmetry energy? How does the symmetry energy affect properties of neutron stars, gravitational waves and our understanding about the nature of strong-field gravity? In this lecture, we try to answer these questions as best as we can based on some of our recent work and/or understanding of research done by others. This note summarizes the main points of the lecture.

  18. Preparation of spherical cobalt carbonate powder with high tap density

    Institute of Scientific and Technical Information of China (English)

    XIAO Jin; WANG Jian-feng; LIU Yong-dong; LI Jie; LIU Ye-xiang

    2006-01-01

    Spherical cobalt carbonate with high tap density, good crystallization and uniform particle size was prepared by controlled chemical crystal method using cobalt chloride and ammonium bicarbonate as cobalt source and precipitator. The effects of pH value and reaction time on crystallization and physical properties of cobalt carbonate were studied. The results show that the key factors influencing the preparation process of spherical cobalt carbonate with high tap density and good crystallization are how to control pH value (7.25 ± 0.05) and keep some reaction time (about 10 h). Co4O3 was prepared by sintering spherical morphology CoCO3 samples at varied temperatures. The results show that as the decomposition temperature increases, the as-obtained Co4O3 products with porous structure transform into polyhedral structure with glazed surface, and simultaneously the cobalt content and tap density increase. However, the specific surface area shows a trend of decrease.

  19. Estimation of free carrier concentrations in high-quality heavily doped GaN:Si micro-rods by photoluminescence and Raman spectroscopy

    Science.gov (United States)

    Mohajerani, M. S.; Khachadorian, S.; Nenstiel, C.; Schimpke, T.; Avramescu, A.; Strassburg, M.; Hoffmann, A.; Waag, A.

    2016-03-01

    The controlled growth of highly n-doped GaN micro rods is one of the major challenges in the fabrication of recently developed three-dimensional (3D) core-shell light emitting diodes (LEDs). In such structures with a large active area, higher electrical conductivity is needed to achieve higher current density. In this contribution, we introduce high quality heavily-doped GaN:Si micro-rods which are key elements of the newly developed 3D core-shell LEDs. These structures were grown by metal-organic vapor phase epitaxy (MOVPE) using selective area growth (SAG). We employed spatially resolved micro-Raman and micro-photoluminescence (PL) in order to directly determine a free-carrier concentration profile in individual GaN micro-rods. By Raman spectroscopy, we analyze the low-frequency branch of the longitudinal optical (LO)-phonon-plasmon coupled modes and estimate free carrier concentrations from ≍ 2.4 × 1019 cm-3 up to ≍ 1.5 × 1020 cm-3. Furthermore, free carrier concentrations are determined by estimating Fermi energy level from the near band edge emission measured by low-temperature PL. The results from both methods reveal a good consistency.

  20. Theoretical Study on the High Energy Density Compound Hexanitrohexaazatricyclotetradecanedifuroxan

    Institute of Scientific and Technical Information of China (English)

    QIU Ling; XIAO He-Ming; ZHU Wei-Hua; JU Xue-Hai; GONG Xue-Dong

    2006-01-01

    Density functional theory (DFT) has been employed to study the molecular geometries, electronic structures,infrared (IR) spectra, and thermodynamic properties of the high energy density compound hexanitrohexaazatricyclotetradecanedifuroxan (HHTTD) at the B3LYP/6-31G** level of theory. The calculated results showthattherearefourconformationalisomers (a, β, γ and δ) for HHTTD, and the relative stabilities of four conformers were assessed based on the calculated total energies and the energy-gaps between the frontier molecular orbitals. The computed harmonic vibrational frequencies are in reasonable agreement with the available experimental data. Thermodynamic properties derived from the IR spectra on the basis of statistical thermodynamic principles are linearly correlated with the temperature. Detonation performances were evaluated by using the Kamlet-Jacobsequationsbasedonthecalculated densities and heats of formation. It was found that four HHTTD isomers with the predicted densities of ca. 2 g·cm-3, detonation velocities near 10 km·s-1, and detonation pressures over 45 Gpa, may be novel potential candidates of high energy density materials (HEDM). These results may provide basic information for the molecular designof HEDM.

  1. A high energy density relaxor antiferroelectric pulsed capacitor dielectric

    Energy Technology Data Exchange (ETDEWEB)

    Jo, Hwan Ryul; Lynch, Christopher S. [Department of Mechanical and Aerospace Engineering, University of California, Los Angeles (UCLA), Los Angeles, California 90095 (United States)

    2016-01-14

    Pulsed capacitors require high energy density and low loss, properties that can be realized through selection of composition. Ceramic (Pb{sub 0.88}La{sub 0.08})(Zr{sub 0.91}Ti{sub 0.09})O{sub 3} was found to be an ideal candidate. La{sup 3+} doping and excess PbO were used to produce relaxor antiferroelectric behavior with slim and slanted hysteresis loops to reduce the dielectric hysteresis loss, to increase the dielectric strength, and to increase the discharge energy density. The discharge energy density of this composition was found to be 3.04 J/cm{sup 3} with applied electric field of 170 kV/cm, and the energy efficiency, defined as the ratio of the discharge energy density to the charging energy density, was 0.920. This high efficiency reduces the heat generated under cyclic loading and improves the reliability. The properties were observed to degrade some with temperature increase above 80 °C. Repeated electric field cycles up to 10 000 cycles were applied to the specimen with no observed performance degradation.

  2. A high current density DC magnetohydrodynamic (MHD) micropump

    NARCIS (Netherlands)

    Homsy, Alexandra; Koster, Sander; Eijkel, Jan C.T.; Berg, van den Albert; Lucklum, F.; Verpoorte, E.; Rooij, de Nico F.

    2005-01-01

    This paper describes the working principle of a DC magnetohydrodynamic (MHD) micropump that can be operated at high DC current densities (J) in 75-µm-deep microfluidic channels without introducing gas bubbles into the pumping channel. The main design feature for current generation is a micromachined

  3. A high current density DC magnetohydrodynamic (MHD) micropump

    NARCIS (Netherlands)

    Homsy, A; Koster, Sander; Eijkel, JCT; van den Berg, A; Lucklum, F; Verpoorte, E; de Rooij, NF

    2005-01-01

    This paper describes the working principle of a DC magnetohydrodynamic (MHD) micropump that can be operated at high DC current densities (J) in 75-mu m-deep microfluidic channels without introducing gas bubbles into the pumping channel. The main design feature for current generation is a micromachin

  4. Intraocular inflammation following endotamponade with high-density silicone oil.

    NARCIS (Netherlands)

    Theelen, T.; Tilanus, M.A.D.; Klevering, B.J.

    2004-01-01

    BACKGROUND: The use of a mixture of silicone oil and partially fluorinated alkanes (high-density silicone oil) has recently been suggested as intraocular tamponade in complicated retinal detachment of the inferior quadrants. We describe a series of patients who developed a clinical picture resemblin

  5. Two-Dimensional Super High Density Multi-Fiber Connector

    Institute of Scientific and Technical Information of China (English)

    Takashi Shigenaga; Katsuki Suematsu; Masao Shinoda; Takayuki Ando

    2003-01-01

    We have developed 32-fiber and 60-fiber super high density multi fiber connector. This 32-fiber connector can be applicable for single-mode fiber and 60-fiber connector for multi-mode fiber. We have also established PC (physical contact) connection technology by optimizing polishing condition and clamping force.

  6. Interaction effects in high density magnetic particulate media

    Energy Technology Data Exchange (ETDEWEB)

    Cerchez, Mihai; Stoleriu, Laurentiu; Stancu, Alexandru

    2004-01-01

    The paper presents a micromagnetic study of the particulate high density recording media. The main difference in the behavior of such a system is the appearance of magnetic clusters which lead to a different behavior of the system. New hypotheses for interpreting such systems are presented.

  7. Metabolism of high density lipoproteins in liver cancer

    Institute of Scientific and Technical Information of China (English)

    Jing-Ting Jiang; Ning Xu; Chang-Ping Wu

    2007-01-01

    Liver plays a vital role in the production and catabolism of plasma lipoproteins. It depends on the integrity of cellular function of liver, which ensures homeostasis of lipid and lipoprotein metabolism. When liver cancer occurs these processes are impaired and high-density lipoproteins are changed.

  8. High Energy Density Physics and Exotic Acceleration Schemes

    Science.gov (United States)

    Cowan, Thomas; Colby, Eric

    2002-12-01

    We summarize the reported results and the principal technical discussions that occurred in our Working Group on High Energy Density Physics and Exotic Acceleration Schemes at the 2002 workshop on Advanced Accelerator Concepts at the Mandalay Beach resort, June 22-28, 2002.

  9. Intraocular inflammation following endotamponade with high-density silicone oil.

    NARCIS (Netherlands)

    Theelen, T.; Tilanus, M.A.D.; Klevering, B.J.

    2004-01-01

    BACKGROUND: The use of a mixture of silicone oil and partially fluorinated alkanes (high-density silicone oil) has recently been suggested as intraocular tamponade in complicated retinal detachment of the inferior quadrants. We describe a series of patients who developed a clinical picture

  10. A Novel Anti-Inflammatory Effect for High Density Lipoprotein.

    Directory of Open Access Journals (Sweden)

    Scott J Cameron

    Full Text Available High density lipoprotein has anti-inflammatory effects in addition to mediating reverse cholesterol transport. While many of the chronic anti-inflammatory effects of high density lipoprotein (HDL are attributed to changes in cell adhesion molecules, little is known about acute signal transduction events elicited by HDL in endothelial cells. We now show that high density lipoprotein decreases endothelial cell exocytosis, the first step in leukocyte trafficking. ApoA-I, a major apolipoprotein of HDL, mediates inhibition of endothelial cell exocytosis by interacting with endothelial scavenger receptor-BI which triggers an intracellular protective signaling cascade involving protein kinase C (PKC. Other apolipoproteins within the HDL particle have only modest effects upon endothelial exocytosis. Using a human primary culture of endothelial cells and murine apo-AI knockout mice, we show that apo-AI prevents endothelial cell exocytosis which limits leukocyte recruitment. These data suggest that high density lipoprotein may inhibit diseases associated with vascular inflammation in part by blocking endothelial exocytosis.

  11. High follicle density does not decrease sweat gland density in Huacaya alpacas.

    Science.gov (United States)

    Moore, K E; Maloney, S K; Blache, D

    2015-01-01

    When exposed to high ambient temperatures, mammals lose heat evaporatively by either sweating from glands in the skin or by respiratory panting. Like other camelids, alpacas are thought to evaporate more water by sweating than panting, despite a thick fleece, unlike sheep which mostly pant in response to heat stress. Alpacas were brought to Australia to develop an alternative fibre industry to sheep wool. In Australia, alpacas can be exposed to ambient temperatures higher than in their native South America. As a young industry there is a great deal of variation in the quality and quantity of the fleece produced in the national flock. There is selection pressure towards animals with finer and denser fleeces. Because the fibre from secondary follicles is finer than that from primary follicles, selecting for finer fibres might alter the ratio of primary and secondary follicles. In turn the selection might alter sweat gland density because the sweat glands are associated with the primary follicle. Skin biopsy and fibre samples were obtained from the mid-section of 33 Huacaya alpacas and the skin sections were processed into horizontal sections at the sebaceous gland level. Total, primary, and secondary follicles and the number of sweat gland ducts were quantified. Fibre samples from each alpaca were further analysed for mean fibre diameter. The finer-fibred animals had a higher total follicle density (P<0.001) and more sweat glands (P<0.001) than the thicker-fibred animals. The fibre diameter and total follicle density were negatively correlated (R(2)=0.56, P<0.001). Given that the finer-fibred animals had higher follicle density and more sweat glands than animals with thicker fibres, we conclude that alpacas with high follicle density should not be limited for potential sweating ability. Copyright © 2014 Elsevier Ltd. All rights reserved.

  12. Interfacial Tension and Surface Pressure of High Density Lipoprotein, Low Density Lipoprotein, and Related Lipid Droplets

    DEFF Research Database (Denmark)

    Ollila, O. H. S.; Lamberg, A.; Lehtivaara, M.

    2012-01-01

    Lipid droplets play a central role in energy storage and metabolism on a cellular scale. Their core is comprised of hydrophobic lipids covered by a surface region consisting of amphiphilic lipids and proteins. For example, high and low density lipoproteins (HDL and LDL, respectively) are essentia...... of interfacial tension becomes significant for particles with a radius of similar to 5 nm, when the area per molecule in the surface region is...

  13. High prevalence of asymptomatic carriers of Tropheryma whipplei in different populations from the North of Spain.

    Science.gov (United States)

    García-Álvarez, Lara; Pérez-Matute, Patricia; Blanco, José Ramón; Ibarra, Valvanera; Oteo, José Antonio

    2016-01-01

    Tropheryma whipplei is the causative agent of Whipple disease. T. whipplei has also been detected in asymptomatic carriers with a very different prevalence. To date, in Spain, there are no data regarding the prevalence of T. whipplei in a healthy population or in HIV-positive patients, or in chronic fatigue syndrome (CFS). Therefore, the aim of this work was to assess the prevalence of T. whipplei in stools in those populations. Stools from 21 HIV-negative subjects, 65 HIV-infected, and 12 CFS patients were analysed using real time-PCR. HIV-negative and positive subjects were divided into two groups, depending on the presence/absence of metabolic syndrome (MS). Positive samples were sequenced. The prevalence of T. whipplei was 25.51% in 98 stool samples analysed. Prevalence in HIV-positive patients was significantly higher than in HIV-negative (33.8% vs. 9.09%, p=0.008). Prevalence in the control group with no associated diseases was 20%, whereas no positive samples were observed in HIV-negative patients with MS, or in those diagnosed with CFS. The prevalence observed in HIV-positive patients without MS was 30.35%, and with MS it was 55.5%. The number of positive samples varies depending on the primers used, although no statistically significant differences were observed. There is a high prevalence of asymptomatic carriers of T. whipplei among healthy and in HIV-infected people from Spain. The role of T. whipplei in HIV patients with MS is unclear, but the prevalence is higher than in other populations. Copyright © 2015 Elsevier España, S.L.U. and Sociedad Española de Enfermedades Infecciosas y Microbiología Clínica. All rights reserved.

  14. Extreme states of matter high energy density physics

    CERN Document Server

    Fortov, Vladimir E

    2016-01-01

    With its many beautiful colour pictures, this book gives fascinating insights into the unusual forms and behaviour of matter under extremely high pressures and temperatures. These extreme states are generated, among other things, by strong shock, detonation and electric explosion waves, dense laser beams,electron and ion beams, hypersonic entry of spacecraft into dense atmospheres of planets, and in many other situations characterized by extremely high pressures and temperatures.Written by one of the world's foremost experts on the topic, this book will inform and fascinate all scientists dealing with materials properties and physics, and also serve as an excellent introduction to plasma-, shock-wave and high-energy-density physics for students and newcomers seeking an overview. This second edition is thoroughly revised and expanded, in particular with new material on high energy-density physics, nuclear explosions and other nuclear transformation processes.

  15. Quark Matter at High Density based on Extended Confined-isospin-density-dependent-mass Model

    CERN Document Server

    Qauli, A I

    2016-01-01

    We investigate the effect of the inclusion of relativistic Coulomb terms in a confined-isospin-density-dependent-mass (CIDDM) model of strange quark matter (SQM). We found that if we include Coulomb term in scalar density form, SQM equation of state (EOS) at high densities is stiffer but if we include Coulomb term in vector density form is softer than that of standard CIDDM model. We also investigate systematically the role of each term of the extended CIDDM model. Compared with what was reported in Ref.~\\cite {ref:isospin}, we found the stiffness of SQM EOS is controlled by the interplay among the the oscillator harmonic, isospin asymmetry and Coulomb contributions depending on the parameter's range of these terms. We have found that the absolute stable condition of SQM and the mass of 2 $M_\\odot$ pulsars can constrain the parameter of oscillator harmonic $\\kappa_1$ $\\approx 0.53$ in the case Coulomb term excluded. If the Coulomb term is included, for the models with their parameters are consistent with SQM ...

  16. High-Density Stacked Ru Nanocrystals for Nonvolatile Memory Application

    Institute of Scientific and Technical Information of China (English)

    MAO Ping; ZHANG Zhi-Gang; PAN Li-Yang; XU Jun; CHEN Pei-Yi

    2009-01-01

    @@ Stacked ruthenium (Ru) nanocrystals (NCs) are formed by rapid thermal annealing for the whole gate stacks and embedded in memory structure, which is compatible with conventional CMOS technology. Ru NCs with high density (3×1012 cm-2 ), small size (2-4 nm) and good uniformity both in aerial distribution and morphology are formed. Attributed to the higher surface trap density, a memory window of 5.2 V is obtained with stacked Ru NCs in comparison to that of 3.5 V with single-layer samples. The stacked Ru NCs device also exhibits much better retention performance because of Coulomb blockade and vertical uniformity between stacked Ru NCs.

  17. Local charge neutrality condition, Fermi level and majority carrier density of a semiconductor with multiple localized multi-level intrinsic/impurity defects

    Institute of Scientific and Technical Information of China (English)

    Ken K. Chin

    2011-01-01

    For semiconductors with localized intrinsic/impurity defects,intentionally doped or unintentionally incorporated,that have multiple transition energy levels among charge states,the general formulation of the local charge neutrality condition is given for the determination of the Fermi level and the majority carrier density.A graphical method is used to illustrate the solution of the problem.Relations among the transition energy levels of the multi-level defect are derived using the graphical method.Numerical examples are given for p-doping of the CdTe thin film used in solar panels and semi-insulating Si to illustrate the relevance and importance of the issues discussed in this work.

  18. High charge carrier mobility and efficient charge separation in highly soluble perylenetetracarboxyl-diimides

    NARCIS (Netherlands)

    Günbaş, D.D.; Xue, C.; Patwardhan,S.; Fravventura, M.C.; Zhang, H.; Jager, W.F.; Sudhölter, E.J.R.; Laurens D. A.; Siebbeles, L.D.A.; Savenije, T.J.; Jin, S.; Grozema, F.C.

    2014-01-01

    In this communication we report on the synthesis and charge mobility of highly soluble perylenebisimid derivatives.We show that introduction of alkylester side chains results in compounds combining a high solubility with charge mobilities up to 0.22 cm2 V_1 s_1. These materials are therefore interes

  19. High-Sensitivity Measurement of Density by Magnetic Levitation.

    Science.gov (United States)

    Nemiroski, Alex; Kumar, A A; Soh, Siowling; Harburg, Daniel V; Yu, Hai-Dong; Whitesides, George M

    2016-03-01

    This paper presents methods that use Magnetic Levitation (MagLev) to measure very small differences in density of solid diamagnetic objects suspended in a paramagnetic medium. Previous work in this field has shown that, while it is a convenient method, standard MagLev (i.e., where the direction of magnetization and gravitational force are parallel) cannot resolve differences in density mm) because (i) objects close in density prevent each other from reaching an equilibrium height due to hard contact and excluded volume, and (ii) using weaker magnets or reducing the magnetic susceptibility of the medium destabilizes the magnetic trap. The present work investigates the use of weak magnetic gradients parallel to the faces of the magnets as a means of increasing the sensitivity of MagLev without destabilization. Configuring the MagLev device in a rotated state (i.e., where the direction of magnetization and gravitational force are perpendicular) relative to the standard configuration enables simple measurements along the axes with the highest sensitivity to changes in density. Manipulating the distance of separation between the magnets or the lengths of the magnets (along the axis of measurement) enables the sensitivity to be tuned. These modifications enable an improvement in the resolution up to 100-fold over the standard configuration, and measurements with resolution down to 10(-6) g/cm(3). Three examples of characterizing the small differences in density among samples of materials having ostensibly indistinguishable densities-Nylon spheres, PMMA spheres, and drug spheres-demonstrate the applicability of rotated Maglev to measuring the density of small (0.1-1 mm) objects with high sensitivity. This capability will be useful in materials science, separations, and quality control of manufactured objects.

  20. Optimized Carrier Tracking Loop Design for Real-Time High-Dynamics GNSS Receivers

    Directory of Open Access Journals (Sweden)

    Pedro A. Roncagliolo

    2012-01-01

    Full Text Available Carrier phase estimation in real-time Global Navigation Satellite System (GNSS receivers is usually performed by tracking loops due to their very low computational complexity. We show that a careful design of these loops allows them to operate properly in high-dynamics environments, that is, accelerations up to 40 g or more. Their phase and frequency discriminators and loop filter are derived considering the digital nature of the loop inputs. Based on these ideas, we propose a new loop structure named Unambiguous Frequency-Aided Phase-Locked Loop (UFA-PLL. In terms of tracking capacity and noise resistance UFA-PLL has the same advantages of frequently used coupled-loop schemes, but it is simpler to design and to implement. Moreover, it can keep phase lock in situations where other loops cannot. The loop design is completed selecting the correlation time and loop bandwidth that minimize the pull-out probability, without relying on typical rules of thumb. Optimal and efficient ways to smooth the phase estimates are also presented. Hence, high-quality phase measurements—usually exploited in offline and quasistatic applications—become practical for real-time and high-dynamics receivers. Experiments with fixed-point implementations of the proposed loops and actual radio signals are also shown.

  1. Rf Gun with High-Current Density Field Emission Cathode

    Energy Technology Data Exchange (ETDEWEB)

    Jay L. Hirshfield

    2005-12-19

    High current-density field emission from an array of carbon nanotubes, with field-emission-transistor control, and with secondary electron channel multiplication in a ceramic facing structure, have been combined in a cold cathode for rf guns and diode guns. Electrodynamic and space-charge flow simulations were conducted to specify the cathode configuration and range of emission current density from the field emission cold cathode. Design of this cathode has been made for installation and testing in an existing S-band 2-1/2 cell rf gun. With emission control and modulation, and with current density in the range of 0.1-1 kA/cm2, this cathode could provide performance and long-life not enjoyed by other currently-available cathodes

  2. Collapsing Bubble in Metal for High Energy Density Physics Study

    Energy Technology Data Exchange (ETDEWEB)

    Ng, S F; Barnard, J J; Leung, P T; Yu, S S

    2011-04-13

    This paper presents a new idea to produce matter in the high energy density physics (HEDP) regime in the laboratory using an intense ion beam. A gas bubble created inside a solid metal may collapse by driving it with an intense ion beam. The melted metal will compress the gas bubble and supply extra energy to it. Simulations show that the spherical implosion ratio can be about 5 and at the stagnation point, the maximum density, temperature and pressure inside the gas bubble can go up to nearly 2 times solid density, 10 eV and a few megabar (Mbar) respectively. The proposed experiment is the first to permit access into the Mbar regime with existing or near-term ion facilities, and opens up possibilities for new physics gained through careful comparisons of simulations with measurements of quantities like stagnation radius, peak temperature and peak pressure at the metal wall.

  3. High energy-density science on the National Ignition Facility

    Energy Technology Data Exchange (ETDEWEB)

    Campbell, E.M.; Cauble, R.; Remington, B.A.

    1997-08-01

    The National Ignition Facility, as well as its French counterpart Le Laser Megajoule, have been designed to confront one of the most difficult and compelling problem in shock physics - the creation of a hot, compassed DT plasma surrounded and confined by cold, nearly degenerate DT fuel. At the same time, these laser facilities will present the shock physics community with unique tools for the study of high energy density matter at states unreachable by any other laboratory technique. Here we describe how these lasers can contribute to investigations of high energy density in the area of material properties and equations of state, extend present laboratory shock techniques such as high-speed jets to new regimes, and allow study of extreme conditions found in astrophysical phenomena.

  4. Rationally designed polyimides for high-energy density capacitor applications.

    Science.gov (United States)

    Ma, Rui; Baldwin, Aaron F; Wang, Chenchen; Offenbach, Ido; Cakmak, Mukerrem; Ramprasad, Rampi; Sotzing, Gregory A

    2014-07-01

    Development of new dielectric materials is of great importance for a wide range of applications for modern electronics and electrical power systems. The state-of-the-art polymer dielectric is a biaxially oriented polypropylene (BOPP) film having a maximal energy density of 5 J/cm(3) and a high breakdown field of 700 MV/m, but with a limited dielectric constant (∼2.2) and a reduced breakdown strength above 85 °C. Great effort has been put into exploring other materials to fulfill the demand of continuous miniaturization and improved functionality. In this work, a series of polyimides were investigated as potential polymer materials for this application. Polyimide with high dielectric constants of up to 7.8 that exhibits low dissipation factors (<1%) and high energy density around 15 J/cm(3), which is 3 times that of BOPP, was prepared. Our syntheses were guided by high-throughput density functional theory calculations for rational design in terms of a high dielectric constant and band gap. Correlations of experimental and theoretical results through judicious variations of polyimide structures allowed for a clear demonstration of the relationship between chemical functionalities and dielectric properties.

  5. Average density and porosity of high-strength lightweight concrete

    Directory of Open Access Journals (Sweden)

    A.S. Inozemtcev

    2014-11-01

    Full Text Available The analysis results of high-strength lightweight concrete (HSLWC structure are presented in this paper. The X-ray tomography, optical microscopy and other methods are used for researching of average density and porosity. It has been revealed that mixtures of HSLWC with density 1300…1500 kg/m3 have a homogeneous structure. The developed concrete has a uniform distribution of the hollow filler and a uniform layer of cement-mineral matrix. The highly saturated gas phase which is divided by denser large particles of quartz sand and products of cement hydration in the contact area allow forming a composite material with low average density, big porosity (up to 40% and high strength (compressive strength is more than 40 MPa. Special modifiers increase adhesion, compacts structure in the contact area, decrease water absorption of high-strength lightweight concrete (up to 1 % and ensure its high water resistance (water resistance coefficient is more than 0.95.

  6. The influence of lubricant carrier and lubrication conditions on mechanical-technological properties of high carbon steel wires

    Directory of Open Access Journals (Sweden)

    M. Suliga

    2016-10-01

    Full Text Available In this paper the effect of the type of soap powder and lubricant carriers on lubrication conditions in multipass drawing process of high carbon steel wires has been determined. The wire drawing process was conducted in industrial conditions by means of a modern multi-die Koch drawing machine. For wires drawn on borax and phosphate lubricant carriers the mechanical-technological properties have been carried out, in which yield stress, tensile strength, uniform elongation, number of twists and number of bends were assessed. It has been proved that the application of phosphate lubricant carrier and also the rotary die in the first draft in an essential way improve the lubrication condition in high speed multipass drawing process and makes it possible to refine the mechanical properties of wires.

  7. Influence of high-pressure treatment on charge carrier transport in PbS colloidal quantum dot solids.

    Science.gov (United States)

    Heo, Seung Jin; Yoon, Seokhyun; Oh, Sang Hoon; Yoon, Doo Hyun; Kim, Hyun Jae

    2014-01-21

    We investigated the effects of high-pressure treatment on charge carrier transport in PbS colloidal quantum dot (CQD) solids. We applied high pressure to PbS CQD solids using nitrogen gas to reduce the inter-dot distance. Using this simple process, we obtained conductive PbS CQD solids. Terahertz time-domain spectroscopy was used to study charge carrier transport as a function of pressure. We found that the minimum pressure needed to increase the dielectric constant, conductivity, and carrier mobility was 4 MPa. All properties dramatically improved at 5 MPa; for example, the mobility increased from 0.13 cm(2) V(-1) s(-1) at 0.1 MPa to 0.91 cm(2) V(-1) s(-1) at 5 MPa. We propose this simple process as a nondestructive approach for making conductive PbS CQD solids that are free of chemical and physical defects.

  8. Next-generation sequencing improves thalassemia carrier screening among premarital adults in a high prevalence population: the Dai nationality, China.

    Science.gov (United States)

    He, Jing; Song, Wenhui; Yang, Jinlong; Lu, Sen; Yuan, Yuan; Guo, Junfu; Zhang, Jie; Ye, Kai; Yang, Fan; Long, Fangfang; Peng, Zhiyu; Yu, Haijing; Cheng, Le; Zhu, Baosheng

    2017-09-01

    Thalassemia is one of the most common monogenic diseases in southwestern China, especially among the Dai ethnic group. Here, we explore the feasibility of a next-generation sequencing (NGS) screening method specifically for the Dai people. Blood samples were obtained from Dai people for premarital screening. Double-blind, parallel hemoglobinopathy screening was conducted using both traditional hematological methods (red cell indexes and hemoglobin electrophoresis, then DNA sequencing) and an NGS approach. Among 951 tested individuals, we found a thalassemia carrier rate of 49.5% (471/951) using the NGS screen, in contrast to 22.0% (209/951) found using traditional methods. Almost 74.8% (217/290) of α-thalassemia carriers and 30.5% (25/82) of composite α- and β-thalassemia carriers were missed by traditional screens. The proportion of such α- and β-thalassemia carriers among the Dai people is 8.6% (82/951). For β-thalassemia carriers, the high ratio (66/99) of CD26 mutations may suggest a correlation between CD26 and the environmental adaption of the Dai people. Methodological comparisons demonstrate the superiority of NGS for both sensitivity and specificity, provide a comprehensive assessment of thalassemia screening strategies, and indicate that NGS is a competitive screening method, especially among populations with a high prevalence of disease.Genet Med advance online publication 26 January 2017.

  9. High power density yeast catalyzed microbial fuel cells

    Science.gov (United States)

    Ganguli, Rahul

    Microbial fuel cells leverage whole cell biocatalysis to convert the energy stored in energy-rich renewable biomolecules such as sugar, directly to electrical energy at high efficiencies. Advantages of the process include ambient temperature operation, operation in natural streams such as wastewater without the need to clean electrodes, minimal balance-of-plant requirements compared to conventional fuel cells, and environmentally friendly operation. These make the technology very attractive as portable power sources and waste-to-energy converters. The principal problem facing the technology is the low power densities compared to other conventional portable power sources such as batteries and traditional fuel cells. In this work we examined the yeast catalyzed microbial fuel cell and developed methods to increase the power density from such fuel cells. A combination of cyclic voltammetry and optical absorption measurements were used to establish significant adsorption of electron mediators by the microbes. Mediator adsorption was demonstrated to be an important limitation in achieving high power densities in yeast-catalyzed microbial fuel cells. Specifically, the power densities are low for the length of time mediator adsorption continues to occur. Once the mediator adsorption stops, the power densities increase. Rotating disk chronoamperometry was used to extract reaction rate information, and a simple kinetic expression was developed for the current observed in the anodic half-cell. Since the rate expression showed that the current was directly related to microbe concentration close to the electrode, methods to increase cell mass attached to the anode was investigated. Electrically biased electrodes were demonstrated to develop biofilm-like layers of the Baker's yeast with a high concentration of cells directly connected to the electrode. The increased cell mass did increase the power density 2 times compared to a non biofilm fuel cell, but the power density

  10. Generating free charges by carrier multiplication in quantum dots for highly efficient photovoltaics.

    Science.gov (United States)

    Ten Cate, Sybren; Sandeep, C S Suchand; Liu, Yao; Law, Matt; Kinge, Sachin; Houtepen, Arjan J; Schins, Juleon M; Siebbeles, Laurens D A

    2015-02-17

    CONSPECTUS: In a conventional photovoltaic device (solar cell or photodiode) photons are absorbed in a bulk semiconductor layer, leading to excitation of an electron from a valence band to a conduction band. Directly after photoexcitation, the hole in the valence band and the electron in the conduction band have excess energy given by the difference between the photon energy and the semiconductor band gap. In a bulk semiconductor, the initially hot charges rapidly lose their excess energy as heat. This heat loss is the main reason that the theoretical efficiency of a conventional solar cell is limited to the Shockley-Queisser limit of ∼33%. The efficiency of a photovoltaic device can be increased if the excess energy is utilized to excite additional electrons across the band gap. A sufficiently hot charge can produce an electron-hole pair by Coulomb scattering on a valence electron. This process of carrier multiplication (CM) leads to formation of two or more electron-hole pairs for the absorption of one photon. In bulk semiconductors such as silicon, the energetic threshold for CM is too high to be of practical use. However, CM in nanometer sized semiconductor quantum dots (QDs) offers prospects for exploitation in photovoltaics. CM leads to formation of two or more electron-hole pairs that are initially in close proximity. For photovoltaic applications, these charges must escape from recombination. This Account outlines our recent progress in the generation of free mobile charges that result from CM in QDs. Studies of charge carrier photogeneration and mobility were carried out using (ultrafast) time-resolved laser techniques with optical or ac conductivity detection. We found that charges can be extracted from photoexcited PbS QDs by bringing them into contact with organic electron and hole accepting materials. However, charge localization on the QD produces a strong Coulomb attraction to its counter charge in the organic material. This limits the production

  11. High energy density capacitors for low cost applications

    Science.gov (United States)

    Iyore, Omokhodion David

    Polyvinylidene fluoride (PVDF) and its copolymers with trifluoroethylene, hexafluoropropylene and chlorotrifluoroethylene are the most widely investigated ferroelectric polymers, due to their relatively high electromechanical properties and potential to achieve high energy density. [Bauer, 2010; Zhou et al., 2009] The research community has focused primarily on melt pressed or extruded films of PVDF-based polymers to obtain the highest performance with energy density up to 25 Jcm-3. [Zhou et al., 2009] Solution processing offers an inexpensive, low temperature alternative, which is also easily integrated with flexible electronics. This dissertation focuses on the fabrication of solution-based polyvinylidene fluoride-hexafluoropropylene metal-insulator-metal capacitors on flexible substrates using a photolithographic process. Capacitors were optimized for maximum energy density, high dielectric strength and low leakage current density. It is demonstrated that with the right choice of solvent, electrodes, spin-casting and annealing conditions, high energy density thin film capacitors can be fabricated repeatably and reproducibly. The high electric field dielectric constants were measured and the reliabilities of the polymer capacitors were also evaluated via time-zero breakdown and time-dependent breakdown techniques. Chapter 1 develops the motivation for this work and provides a theoretical overview of dielectric materials, polarization, leakage current and dielectric breakdown. Chapter 2 is a literature review of polymer-based high energy density dielectrics and covers ferroelectric polymers, highlighting PVDF and some of its derivatives. Chapter 3 summarizes some preliminary experimental work and presents materials and electrical characterization that support the rationale for materials selection and process development. Chapter 4 discusses the fabrication of solution-processed PVDF-HFP and modification of its properties by photo-crosslinking. It is followed by a

  12. The High Density Region of QCD from an Effective Model

    CERN Document Server

    De Pietri, R; Seiler, E; Stamatescu, I O

    2007-01-01

    We study the high density region of QCD within an effective model obtained in the frame of the hopping parameter expansion and choosing Polyakov-type loops as the main dynamical variables representing the fermionic matter. This model still shows the so-called sign problem, a difficulty peculiar to non-zero chemical potential, but it permits the development of algorithms which ensure a good overlap of the simulated Monte Carlo ensemble with the true one. We review the main features of the model and present results concerning the dependence of various observables on the chemical potential and on the temperature, in particular of the charge density and the Polykov loop susceptibility, which may be used to characterize the various phases expected at high baryonic density. In this way, we obtain information about the phase structure of the model and the corresponding phase transitions and cross over regions, which can be considered as hints about the behaviour of non-zero density QCD.

  13. High Energy Density Regenerative Fuel Cell Systems for Terrestrial Applications

    Science.gov (United States)

    Burke, Kenneth A.

    1999-01-01

    Regenerative Fuel Cell System (RFCS) technology for energy storage has been a NASA power system concept for many years. Compared to battery-based energy storage systems, RFCS has received relatively little attention or resources for development because the energy density and electrical efficiency were not sufficiently attractive relative to advanced battery systems. Even today, RFCS remains at a very low technology readiness level (TRL of about 2 indicating feasibility has been demonstrated). Commercial development of the Proton Exchange Membrane (PEM) fuel cells for automobiles and other terrestrial applications and improvements in lightweight pressure vessel design to reduce weight and improve performance make possible a high energy density RFCS energy storage system. The results from this study of a lightweight RFCS energy storage system for a remotely piloted, solar-powered, high altitude aircraft indicate an energy density up to 790 w-h/kg with electrical efficiency of 53.4% is attainable. Such an energy storage system would allow a solar-powered aircraft to carry hundreds of kilograms of payload and remain in flight indefinitely for use in atmospheric research, earth observation, resource mapping. and telecommunications. Future developments in the areas of hydrogen and oxygen storage, pressure vessel design, higher temperature and higher- pressure fuel cell operation, unitized regenerative fuel cells, and commercial development of fuel cell technology will improve both the energy density and electrical efficiency of the RFCS.

  14. High-density housing that works for all

    Energy Technology Data Exchange (ETDEWEB)

    Hasan, Arif

    2010-03-15

    In an urbanising world, the way people fit into cities is vastly important - socially, economically, environmentally, even psychologically. So density, or the number of people living in a given area, is central to urban design and planning. Both governments and markets tend to get density wrong, leading to overcrowding, urban sprawl or often both. A case in point are the high-rise buildings springing up throughtout urban Asia - perceived as key features of that widely touted concept, the 'world-class city'. While some may offer a viable solution to land pressures and density requirements, many built to house evicted or resettled 'slum' dwellers are a social and economic nightmare - inconveniently sited, overcrowded and costly. New evidence from Karachi, Pakistan, reveals a real alternative. Poor people can create liveable high-density settlements as long as community control, the right technical assistance and flexible designs are in place. A city is surely 'world-class' only when it is cosmopolitan – built to serve all, including the poorest.

  15. Hepatic lipase, genetically elevated high-density lipoprotein, and risk of ischemic cardiovascular disease

    DEFF Research Database (Denmark)

    Johannsen, Trine Holm; Kamstrup, Pia R; Andersen, Rolf V

    2008-01-01

    CONTEXT: Hepatic lipase influences metabolism of high-density lipoprotein (HDL), a risk factor for ischemic cardiovascular disease (ICD: ischemic heart disease and ischemic cerebrovascular disease). OBJECTIVE: We tested the hypothesis that genetic variation in the hepatic lipase genetic variants V.......91 (95% CI 0.89-0.94), respectively; this calculation assumes that genetically elevated HDL levels confer decreased risk similar to common HDL elevations. In contrast, when all cases and controls were combined, the observed odds ratios for ICD for these three genetic variants vs. noncarriers were 1.19 (0.......76-1.88), 1.04 (0.96-1.13), and 1.08 (0.89-1.30), respectively. Hazard/odds ratios for ICD in carriers vs. noncarriers of the four remaining hepatic lipase genetic variants did not differ consistently from 1.0. CONCLUSION: Hepatic lipase genetic variants with elevated levels of HDL cholesterol did...

  16. Development of high power density cathode materials for Li-ion batteries

    Energy Technology Data Exchange (ETDEWEB)

    Ketterer, B.; Vasilchina, H.; Seemann, K.; Ulrich, S.; Besser, H.; Pfleging, W.; Kaiser, T.; Adelhelm, C. [Forschungszentrum Karlsruhe (Germany). IMF I

    2008-10-15

    Cathode material for Li-ion batteries can be synthesised by r.f. magnetron sputtering of LiCoO{sub 2} targets in a pure Ar plasma. This technique is suitable for large-scale implementation in foil coating set-ups. By choosing the process parameters and by employing post heat treatment nanocrystalline, stoichiometrical LiCoO{sub 2} films can be fabricated which exhibit the desired high temperature phase. The determination of the elementary composition is possible by optical emission spectroscopy including plasma stimulation and carrier gas temperature extraction. The proof of crystal structure is carried out by X-ray diffraction and Raman spectroscopy. Heat treatment can be conventionally realised in a furnace or by laser impact. With regard to increasing the power density, the surface of the cathode material can be enhanced six-fold by laser-assisted surface patterning. (orig.)

  17. Industrially feasible, dopant-free, carrier-selective contacts for high-efficiency silicon solar cells

    KAUST Repository

    Yang, Xinbo

    2017-05-31

    Dopant-free, carrier-selective contacts (CSCs) on high efficiency silicon solar cells combine ease of deposition with potential optical benefits. Electron-selective titanium dioxide (TiO) contacts, one of the most promising dopant-free CSC technologies, have been successfully implemented into silicon solar cells with an efficiency over 21%. Here, we report further progress of TiO contacts for silicon solar cells and present an assessment of their industrial feasibility. With improved TiO contact quality and cell processing, a remarkable efficiency of 22.1% has been achieved using an n-type silicon solar cell featuring a full-area TiO contact. Next, we demonstrate the compatibility of TiO contacts with an industrial contact-firing process, its low performance sensitivity to the wafer resistivity, its applicability to ultrathin substrates as well as its long-term stability. Our findings underscore the great appeal of TiO contacts for industrial implementation with their combination of high efficiency with robust fabrication at low cost.

  18. High-temperature adsorption layers based on fluoridated polyimide and diatomite carrier

    Science.gov (United States)

    Yakovleva, E. Yu.; Shundrina, I. K.; Gerasimov, E. Yu.

    2017-09-01

    A way of preparing separation layers by the pyrolysis of fluorinated polyimide obtained from 2,4,6-trimethyl- m-phenylenediamine (2,4,6-TM mPDA) and 2,2-bis(3',4'-dicarboxyphenyl)hexafluoropropane (6FDA) applied onto a diatomite carrier is described. Thermogravimetry, elemental analysis, low-temperature nitrogen adsorption, high-resolution electron microscopy, and gas chromatography are used to study changes in the texture and chromatographic characteristics of these layers. It is found that changes in the structure and the effectivity of separation characteristic of the layers depend on the temperature of pyrolysis, which ranges from 250 to 1100°C. It is established that a layer of separation is formed at 250-350°C, and the order of elution of hydrocarbons is similar to their chromatographic behavior on such stationary phases as OV-101. Layers of amorphous carbon formed on the surfaces of individual particles on a diatomite surface at 500-700°C. These layers ensure highly stable and selective separation of permanent gases and hydrocarbons when they are present together.

  19. Carrier Envelope Phase Controlled High-Order Harmonic Generation in Ultrashort Laser Pulse

    Institute of Scientific and Technical Information of China (English)

    WANG Bing-Bing; CHEN Jing; LIU Jie; LI Xiao-Feng; FU Pan-Ming

    2005-01-01

    @@ We investigate the carrier envelope phase (CEP) effects on high-order harmonic generation (HHG) in ultrashort pulses with the pulse duration 2.5fs when the laser intensity is high enough so that the initial state is ionized effectively during the laser pulse but remains about 20% population at the end of the laser pulse. We find that the ionization process of the initial state is very sensitive to the CEP during the laser pulse. The ionization process of the initial state determines the continuum state population and hence influences dramatically the weights of the classical trajectories that contribute to HHG. In such a case we can not predict the cutoff and the structure of the harmonic spectrum only by the number and the kinetic energy of the classical trajectories. The harmonic spectrum exhibits abundant characters for different CEP cases. As a result, we can control the cutoff frequency and the plateau structure of the harmonic spectrum with CEP by controlling the time behaviour of the ionization of the initial state.

  20. Design of High Power Density Amplifiers: Application to Ka Band

    Science.gov (United States)

    Passi, Davide; Leggieri, Alberto; Di Paolo, Franco; Bartocci, Marco; Tafuto, Antonio

    2017-06-01

    Recent developments in the design of high-power-high-frequency amplifiers are assessed in this paper by the analysis and measurements of a high power density amplifier operating in the Ka Band. Design procedure is presented and a technical investigation is reported. The proposed device has shown over 23% of useful frequency bandwidth. It is an ensemble of 16 monolithic solid state power amplifiers that employees mixed technologies as spatial and planar combiners. Test performed have given maximum delivered power of 47.2 dBm.

  1. The use of low density high accuracy (LDHA) data for correction of high density low accuracy (HDLA) point cloud

    Science.gov (United States)

    Rak, Michal Bartosz; Wozniak, Adam; Mayer, J. R. R.

    2016-06-01

    Coordinate measuring techniques rely on computer processing of coordinate values of points gathered from physical surfaces using contact or non-contact methods. Contact measurements are characterized by low density and high accuracy. On the other hand optical methods gather high density data of the whole object in a short time but with accuracy at least one order of magnitude lower than for contact measurements. Thus the drawback of contact methods is low density of data, while for non-contact methods it is low accuracy. In this paper a method for fusion of data from two measurements of fundamentally different nature: high density low accuracy (HDLA) and low density high accuracy (LDHA) is presented to overcome the limitations of both measuring methods. In the proposed method the concept of virtual markers is used to find a representation of pairs of corresponding characteristic points in both sets of data. In each pair the coordinates of the point from contact measurements is treated as a reference for the corresponding point from non-contact measurement. Transformation enabling displacement of characteristic points from optical measurement to their match from contact measurements is determined and applied to the whole point cloud. The efficiency of the proposed algorithm was evaluated by comparison with data from a coordinate measuring machine (CMM). Three surfaces were used for this evaluation: plane, turbine blade and engine cover. For the planar surface the achieved improvement was of around 200 μm. Similar results were obtained for the turbine blade but for the engine cover the improvement was smaller. For both freeform surfaces the improvement was higher for raw data than for data after creation of mesh of triangles.

  2. A Tale of Two Electrons: Correlation at High Density

    CERN Document Server

    Loos, Pierre-François

    2010-01-01

    We review our recent progress in the determination of the high-density correlation energy $\\Ec$ in two-electron systems. Several two-electron systems are considered, such as the well known helium-like ions (helium), and the Hooke's law atom (hookium). We also present results regarding two electrons on the surface of a sphere (spherium), and two electrons trapped in a spherical box (ballium). We also show that, in the large-dimension limit, the high-density correlation energy of two opposite-spin electrons interacting {\\em via} a Coulomb potential is given by $\\Ec \\sim -1/(8D^2)$ for any radial external potential $V(r)$, where $D$ is the dimensionality of the space. This result explains the similarity of $\\Ec$ in the previous two-electron systems for $D=3$.

  3. Lithium-Based High Energy Density Flow Batteries

    Science.gov (United States)

    Bugga, Ratnakumar V. (Inventor); West, William C. (Inventor); Kindler, Andrew (Inventor); Smart, Marshall C. (Inventor)

    2014-01-01

    Systems and methods in accordance with embodiments of the invention implement a lithium-based high energy density flow battery. In one embodiment, a lithium-based high energy density flow battery includes a first anodic conductive solution that includes a lithium polyaromatic hydrocarbon complex dissolved in a solvent, a second cathodic conductive solution that includes a cathodic complex dissolved in a solvent, a solid lithium ion conductor disposed so as to separate the first solution from the second solution, such that the first conductive solution, the second conductive solution, and the solid lithium ionic conductor define a circuit, where when the circuit is closed, lithium from the lithium polyaromatic hydrocarbon complex in the first conductive solution dissociates from the lithium polyaromatic hydrocarbon complex, migrates through the solid lithium ionic conductor, and associates with the cathodic complex of the second conductive solution, and a current is generated.

  4. Solvent additive to achieve highly ordered nanostructural semicrystalline DPP copolymers: toward a high charge carrier mobility.

    Science.gov (United States)

    An, Tae Kyu; Kang, Il; Yun, Hui-jun; Cha, Hyojung; Hwang, Jihun; Park, Seonuk; Kim, Jiye; Kim, Yu Jin; Chung, Dae Sung; Kwon, Soon-Ki; Kim, Yun-Hi; Park, Chan Eon

    2013-12-23

    A facile spin-coating method in which a small percentage of the solvent additive, 1-chloronaphthalene (CN), is found to increase the drying time during film deposition, is reported. The field-effect mobility of a PDPPDBTE film cast from a chloroform-CN mixed solution is 0.46 cm(2) V(-1) s(-1). The addition of CN to the chloroform solution facilitates the formation of highly crystalline polymer structures.

  5. High energy density capacitor testing for the AFWL SHIVA

    Science.gov (United States)

    Smith, D. L.; Reinovsky, R. E.

    Lifetime testing and analysis of small samples of high energy density (HED) discharge capacitors at the AFWL were conducted to find a component suitable for upgrading the SHIVA capacitor bank to a 6 MJ facility. Evaluation was performed with discharge conditions of approximately 250 kA per capacitor at 60 to 70% reversal and 2 microsec quarter period. Dielectric systems including Kraft paper with caster oil impregnant and Kraft paper, polypropylene with DiOctyl Phthalate (DOP) impregnant were tested.

  6. Polypropylene-(high density polyethylene) precipitation from stirred solutions

    OpenAIRE

    Esperidião,Maria Cecília Azevedo; Galembeck,Fernando

    1993-01-01

    Texto completo: acesso restrito. p.993–997 The fast precipitation of mixtures of polypropylene (PP) with high density polyethylene (HDPE) from decalin solutions is affected by the stirring rate of the solutions. With fast stirring, two types of precipitates were obtained viz. globules dispersed in the liquid phase and fibres adhering to the stirrer. Studies by i.r., WAXD, DSC and optical microscopy indicated that the fibrous precipitate is more birefringent, richer in HDPE and richer in th...

  7. Flexible and Lightweight Fuel Cell with High Specific Power Density.

    Science.gov (United States)

    Ning, Fandi; He, Xudong; Shen, Yangbin; Jin, Hehua; Li, Qingwen; Li, Da; Li, Shuping; Zhan, Yulu; Du, Ying; Jiang, Jingjing; Yang, Hui; Zhou, Xiaochun

    2017-06-27

    Flexible devices have been attracting great attention recently due to their numerous advantages. But the energy densities of current energy sources are still not high enough to support flexible devices for a satisfactory length of time. Although proton exchange membrane fuel cells (PEMFCs) do have a high-energy density, traditional PEMFCs are usually too heavy, rigid, and bulky to be used in flexible devices. In this research, we successfully invented a light and flexible air-breathing PEMFC by using a new design of PEMFC and a flexible composite electrode. The flexible air-breathing PEMFC with 1 × 1 cm(2) working area can be as light as 0.065 g and as thin as 0.22 mm. This new PEMFC exhibits an amazing specific volume power density as high as 5190 W L(-1), which is much higher than traditional (air-breathing) PEMFCs. Also outstanding is that the flexible PEMFC retains 89.1% of its original performance after being bent 600 times, and it retains its original performance after being dropped five times from a height of 30 m. Moreover, the research has demonstrated that when stacked, the flexible PEMFCs are also useful in mobile applications such as mobile phones. Therefore, our research shows that PEMFCs can be made light, flexible, and suitable for applications in flexible devices. These innovative flexible PEMFCs may also notably advance the progress in the PEMFC field, because flexible PEMFCs can achieve high specific power density with small size, small volume, low weight, and much lower cost; they are also much easier to mass produce.

  8. Anti-Ferroelectric Ceramics for High Energy Density Capacitors

    Directory of Open Access Journals (Sweden)

    Aditya Chauhan

    2015-11-01

    Full Text Available With an ever increasing dependence on electrical energy for powering modern equipment and electronics, research is focused on the development of efficient methods for the generation, storage and distribution of electrical power. In this regard, the development of suitable dielectric based solid-state capacitors will play a key role in revolutionizing modern day electronic and electrical devices. Among the popular dielectric materials, anti-ferroelectrics (AFE display evidence of being a strong contender for future ceramic capacitors. AFE materials possess low dielectric loss, low coercive field, low remnant polarization, high energy density, high material efficiency, and fast discharge rates; all of these characteristics makes AFE materials a lucrative research direction. However, despite the evident advantages, there have only been limited attempts to develop this area. This article attempts to provide a focus to this area by presenting a timely review on the topic, on the relevant scientific advancements that have been made with respect to utilization and development of anti-ferroelectric materials for electric energy storage applications. The article begins with a general introduction discussing the need for high energy density capacitors, the present solutions being used to address this problem, and a brief discussion of various advantages of anti-ferroelectric materials for high energy storage applications. This is followed by a general description of anti-ferroelectricity and important anti-ferroelectric materials. The remainder of the paper is divided into two subsections, the first of which presents various physical routes for enhancing the energy storage density while the latter section describes chemical routes for enhanced storage density. This is followed by conclusions and future prospects and challenges which need to be addressed in this particular field.

  9. Nanostructured thin solid oxide fuel cells with high power density.

    Science.gov (United States)

    Ignatiev, Alex; Chen, Xin; Wu, Naijuan; Lu, Zigui; Smith, Laverne

    2008-10-28

    Nanostructured thin film solid oxide fuel cells (SOFC) have been developed for reduced temperature operation, with high power density, and to be self reforming. A thin film electrolyte (1-2 microm thickness), e.g., yttria-stabilized zirconia (YSZ), is deposited on a nickel foil substrate. The electrolyte thin film is polycrystalline when deposited on a polycrystalline nickel foil substrate, and is (100) textured when deposited on an atomically textured nickel foil substrate. The Ni foil substrate is then converted into a porous SOFC anode by photolithographic patterning and etching to develop porosity. A composite La(0.5)Sr(0.5)CoO(3) cathode is then deposited on the thin film electrolyte. The resultant thin film hetero structure fuel cells have operated at a significantly reduced temperature: as low as 470 degrees C, with a maximum power density of 140 mW cm(-2) at 575 degrees C, and an efficiency of >50%. This drastic reduction in operating temperature for an SOFC now also allows for the use of hydrocarbon fuels without the need for a separate reformer as the nickel anode effectively dissociates hydrocarbons within this temperature range. These nanostructured fuel cells show excellent potential for high power density, small volume, high efficiency fuel cells for power generation applications.

  10. High Energy Density Physics and Exotic Acceleration Schemes

    Energy Technology Data Exchange (ETDEWEB)

    Cowan, T.; /General Atomics, San Diego; Colby, E.; /SLAC

    2005-09-27

    The High Energy Density and Exotic Acceleration working group took as our goal to reach beyond the community of plasma accelerator research with its applications to high energy physics, to promote exchange with other disciplines which are challenged by related and demanding beam physics issues. The scope of the group was to cover particle acceleration and beam transport that, unlike other groups at AAC, are not mediated by plasmas or by electromagnetic structures. At this Workshop, we saw an impressive advancement from years past in the area of Vacuum Acceleration, for example with the LEAP experiment at Stanford. And we saw an influx of exciting new beam physics topics involving particle propagation inside of solid-density plasmas or at extremely high charge density, particularly in the areas of laser acceleration of ions, and extreme beams for fusion energy research, including Heavy-ion Inertial Fusion beam physics. One example of the importance and extreme nature of beam physics in HED research is the requirement in the Fast Ignitor scheme of inertial fusion to heat a compressed DT fusion pellet to keV temperatures by injection of laser-driven electron or ion beams of giga-Amp current. Even in modest experiments presently being performed on the laser-acceleration of ions from solids, mega-amp currents of MeV electrons must be transported through solid foils, requiring almost complete return current neutralization, and giving rise to a wide variety of beam-plasma instabilities. As keynote talks our group promoted Ion Acceleration (plenary talk by A. MacKinnon), which historically has grown out of inertial fusion research, and HIF Accelerator Research (invited talk by A. Friedman), which will require impressive advancements in space-charge-limited ion beam physics and in understanding the generation and transport of neutralized ion beams. A unifying aspect of High Energy Density applications was the physics of particle beams inside of solids, which is proving to

  11. Investigation of carriers of lustrous carbon at high temperatures by infrared spectroscopy (FTIR

    Directory of Open Access Journals (Sweden)

    S. Eichholz

    2010-10-01

    Full Text Available Lustrous carbon is very important in processes of iron casting in green sand. Lustrous carbon (pirografit is a microcrystalline carbon form, which evolves from a gaseous phase. In the case of applying additions, generating lustrous carbon, for sands with bentonite, there is always a danger of emitting – due to a high temperature of liquid cast iron and a humidity - compounds hazardous for a human health. There can be: CO, SO2, benzene, toluene, ethylbenzene, xylene (the so-called: BTEX as well as polycyclic aromatic hydrocarbons(PAHs. In order to asses the selected mixtures: bentonite – carrier of lustrous carbon, in which a coal dust fraction was limited, thethermogravimetric analysis and the analysis of evolving gases were performed. Examinations were carried out in the ApplictaionsLaboratory NITZSCH-Gerätebau GmbH ,Selb/Bavaria, Germany. The NETZSCH TG 209 F1 Iris® thermal analyzer coupled to the BRUKER Optics FTIR TENSOR(TM was used to measure.

  12. Carrier-wave steepened pulses and gradient-gated high-order harmonic generation

    CERN Document Server

    Radnor, S B P; Kinsler, P; New, G H C

    2008-01-01

    We show how to optimize the process of high-harmonic generation (HHG) by gating the interaction using the field gradient of the driving pulse. Since maximized field gradients are efficiently generated by self-steepening processes, we first present a generalized theory of optical carrier-wave self-steepened (CSS) pulses. This goes beyond existing treatments, which only consider third-order nonlinearity, and has the advantage of describing pulses whose wave forms have a range of symmetry properties. Although a fertile field for theoretical work, CSS pulses are difficult to realize experimentally because of the deleterious effect of dispersion. We therefore consider synthesizing CSS-like profiles using a suitably phased sub-set of the harmonics present in a true CSS wave form. Using standard theoretical models of HHG, we show that the presence of gradient-maximized regions on the wave forms can raise the spectral cut-off and so yield shorter attosecond pulses. We study how the quality of the attosecond bursts cr...

  13. Highly Selective Perchlorate Membrane Electrode Based on Cobalt(Ⅲ) Schiff Base as a Neutral Carrier

    Institute of Scientific and Technical Information of China (English)

    SHOKROLLAHI Ardeshir; GHAEDI Mehrorang; RAJABI, Harold Reza; KIANFAR, Ali Hossein

    2009-01-01

    A highly selective poly(vinyl chloride) (PVC) membrane electrode based on Co(Ⅲ)-Schiff base [Co(5-NO2-Salen)(PBu3)]ClO4·H2O (where 5-NO2-SalenH=bis(5-nitrosalycilaldehyde)ethylenediamine) as a new carrier for construction of perchlorate-selective electrode by incorporating the membrane ingredients on the surface of a graphite electrodes has been reported. The proposed electrode possesses a very wide Nernestian potential linear range to perchlorate from 1.0×10-6 to 5.0×10-1 mol·L-1 with a slope of (59.4±0.9) mV per decade of perchlo-rate concentration with a low detection limit of 5.0×10-7 mol·L-1 and good perchlorate selectivity over the wide variety of other anions. The developed electrode has an especially fast response (<5 s) and a wide pH independent range (3.0-12.0) in comparison with recent reported electrodes and can be used for at least 2 months without any considerable divergence in their potential response. This electrode was used for the determination of perchlorate in river water, drinking water, sludgy water and human urine with satisfactory results without complicated and time consuming pretreatment.

  14. High energy density Z-pinch plasmas using flow stabilization

    Energy Technology Data Exchange (ETDEWEB)

    Shumlak, U., E-mail: shumlak@uw.edu; Golingo, R. P., E-mail: shumlak@uw.edu; Nelson, B. A., E-mail: shumlak@uw.edu; Bowers, C. A., E-mail: shumlak@uw.edu; Doty, S. A., E-mail: shumlak@uw.edu; Forbes, E. G., E-mail: shumlak@uw.edu; Hughes, M. C., E-mail: shumlak@uw.edu; Kim, B., E-mail: shumlak@uw.edu; Knecht, S. D., E-mail: shumlak@uw.edu; Lambert, K. K., E-mail: shumlak@uw.edu; Lowrie, W., E-mail: shumlak@uw.edu; Ross, M. P., E-mail: shumlak@uw.edu; Weed, J. R., E-mail: shumlak@uw.edu [Aerospace and Energetics Research Program, University of Washington, Seattle, Washington, 98195-2250 (United States)

    2014-12-15

    The ZaP Flow Z-Pinch research project[1] at the University of Washington investigates the effect of sheared flows on MHD instabilities. Axially flowing Z-pinch plasmas are produced that are 100 cm long with a 1 cm radius. The plasma remains quiescent for many radial Alfvén times and axial flow times. The quiescent periods are characterized by low magnetic mode activity measured at several locations along the plasma column and by stationary visible plasma emission. Plasma evolution is modeled with high-resolution simulation codes – Mach2, WARPX, NIMROD, and HiFi. Plasma flow profiles are experimentally measured with a multi-chord ion Doppler spectrometer. A sheared flow profile is observed to be coincident with the quiescent period, and is consistent with classical plasma viscosity. Equilibrium is determined by diagnostic measurements: interferometry for density; spectroscopy for ion temperature, plasma flow, and density[2]; Thomson scattering for electron temperature; Zeeman splitting for internal magnetic field measurements[3]; and fast framing photography for global structure. Wall stabilization has been investigated computationally and experimentally by removing 70% of the surrounding conducting wall to demonstrate no change in stability behavior.[4] Experimental evidence suggests that the plasma lifetime is only limited by plasma supply and current waveform. The flow Z-pinch concept provides an approach to achieve high energy density plasmas,[5] which are large, easy to diagnose, and persist for extended durations. A new experiment, ZaP-HD, has been built to investigate this approach by separating the flow Z-pinch formation from the radial compression using a triaxial-electrode configuration. This innovation allows more detailed investigations of the sheared flow stabilizing effect, and it allows compression to much higher densities than previously achieved on ZaP by reducing the linear density and increasing the pinch current. Experimental results and

  15. Novel Structural Components Contribute to the High Thermal Stability of Acyl Carrier Protein from Enterococcus faecalis.

    Science.gov (United States)

    Park, Young-Guen; Jung, Min-Cheol; Song, Heesang; Jeong, Ki-Woong; Bang, Eunjung; Hwang, Geum-Sook; Kim, Yangmee

    2016-01-22

    Enterococcus faecalis is a Gram-positive, commensal bacterium that lives in the gastrointestinal tracts of humans and other mammals. It causes severe infections because of high antibiotic resistance. E. faecalis can endure extremes of temperature and pH. Acyl carrier protein (ACP) is a key element in the biosynthesis of fatty acids responsible for acyl group shuttling and delivery. In this study, to understand the origin of high thermal stabilities of E. faecalis ACP (Ef-ACP), its solution structure was investigated for the first time. CD experiments showed that the melting temperature of Ef-ACP is 78.8 °C, which is much higher than that of Escherichia coli ACP (67.2 °C). The overall structure of Ef-ACP shows the common ACP folding pattern consisting of four α-helices (helix I (residues 3-17), helix II (residues 39-53), helix III (residues 60-64), and helix IV (residues 68-78)) connected by three loops. Unique Ef-ACP structural features include a hydrophobic interaction between Phe(45) in helix II and Phe(18) in the α1α2 loop and a hydrogen bonding between Ser(15) in helix I and Ile(20) in the α1α2 loop, resulting in its high thermal stability. Phe(45)-mediated hydrophobic packing may block acyl chain binding subpocket II entry. Furthermore, Ser(58) in the α2α3 loop in Ef-ACP, which usually constitutes a proline in other ACPs, exhibited slow conformational exchanges, resulting in the movement of the helix III outside the structure to accommodate a longer acyl chain in the acyl binding cavity. These results might provide insights into the development of antibiotics against pathogenic drug-resistant E. faecalis strains.

  16. Hydrodynamic Instabilities in High-Energy-Density Settings

    Science.gov (United States)

    Smalyuk, Vladimir

    2016-10-01

    Our understanding of hydrodynamic instabilities, such as the Rayleigh-Taylor (RT), Richtmyer-Meshkov (RM), and Kelvin-Helmholtz (KH) instabilities, in high-energy-density (HED) settings over past two decades has progressed enormously. The range of conditions where hydrodynamic instabilities are experimentally observed now includes direct and indirect drive inertial confinement fusion (ICF) where surprises continue to emerge, linear and nonlinear regimes, classical interfaces vs. stabilized ablation fronts, tenuous ideal plasmas vs. high density Fermi degenerate plasmas, bulk fluid interpenetration vs. mixing down to the atomic level, in the presence of magnetic fields and/or intense radiation, and in solid state plastic flow at high pressures and strain rates. Regimes in ICF can involve extreme conditions of matter with temperatures up to kilovolts, densities of a thousand times solid densities, and time scales of nanoseconds. On the other hand, scaled conditions can be generated that map to exploding stars (supernovae) with length and time scales of millions of kilometers and hours to days or even years of instability evolution, planetary formation dynamics involving solid-state plastic flow which severely modifies the RT growth and continues to challenge reliable theoretical descriptions. This review will look broadly at progress in probing and understanding hydrodynamic instabilities in these very diverse HED settings, and then will examine a few cases in more depth to illustrate the detailed science involved. Experimental results on large-scale HED facilities such as the Omega, Nike, Gekko, and Shenguang lasers will be reviewed and the latest developments at the National Ignition Facility (NIF) and Z machine will be covered. Finally, current overarching questions and challenges will be summarized to motivate research directions for future. This work was performed under the auspices of the U.S. Department of Energy by LLNL under Contract DE-AC52-07NA27344.

  17. Aromatic Polyurea Possessing High Electrical Energy Density and Low Loss

    Science.gov (United States)

    Thakur, Yash; Lin, Minren; Wu, Shan; Zhang, Q. M.

    2016-10-01

    We report the development of a dielectric polymer, poly (ether methyl ether urea) (PEMEU), which possesses a dielectric constant of 4 and is thermally stable up to 150°C. The experimental results show that the ether units are effective in softening the rigid polymer and making it thermally processable, while the high dipole moment of urea units and glass structure of the polymer leads to a low dielectric loss and low conduction loss. As a result, PEMEU high quality thin films can be fabricated which exhibit exceptionally high breakdown field of >1.5 GV/m, and a low conduction loss at fields up to the breakdown. Consequently, the PEMEU films exhibit a high charge-discharge efficiency of 90% and a high discharged energy density of 36 J/cm3.

  18. High power density reactors based on direct cooled particle beds

    Science.gov (United States)

    Powell, J. R.; Horn, F. L.

    Reactors based on direct cooled High Temperature Gas Cooled Reactor (HTGR) type particle fuel are described. The small diameter particle fuel is packed between concentric porous cylinders to make annular fuel elements, with the inlet coolant gas flowing inwards. Hot exit gas flows out along the central channel of each element. Because of the very large heat transfer area in the packed beds, power densities in particle bed reactors (PBRs) are extremely high resulting in compact, lightweight systems. Coolant exit temperatures are high, because of the ceramic fuel temperature capabilities, and the reactors can be ramped to full power and temperature very rapidly. PBR systems can generate very high burst power levels using open cycle hydrogen coolant, or high continuous powers using closed cycle helium coolant. PBR technology is described and development requirements assessed.

  19. High-density cervical ureaplasma urealyticum colonization in pregnant women

    Directory of Open Access Journals (Sweden)

    Ranđelović Gordana

    2006-01-01

    Full Text Available Background/aim: Ureaplasma urealyticum, a common commensal of the female lower genital tract, has been observed as an important opportunistic pathogen during pregnancy. The aims of this study were to determine the degree of cervical colonization with U. urealyticum in pregnant women with risk pregnancy and in pregnant women with normal term delivery and to evaluate the correlation between high-density cervical U. urealyticum colonization and premature rupture of membranes (PROM as well. Methods. This research was conducted on the samples comprising 130 hospitalized pregnant women with threatening preterm delivery and premature rupture of membranes. The control group consisted of 39 pregnant women with term delivery without PROM. In addition to standard bacteriological examination and performing direct immunofluorescence test to detect Chlamydia trachomatis, cervical swabs were also examined for the presence of U. urealyticum and Mycoplasma hominis by commercially available Mycofast Evolution 2 test (International Microbio, France. Results. The number of findings with isolated high-density U. urealyticum in the target group was 69 (53.08%, while in the control group was 14 (35.90%. Premature rupture of membranes (PROM occurred in 43 (33.08% examinees: 29 were pPROM, and 14 were PROM. The finding of U.urealyticum ≥104 was determined in 25 (58.14% pregnant women with rupture, 17 were pPROM, and 8 were PROM. There was statistically significant difference in the finding of high-density U. urealyticum between the pregnant women with PROM and the control group (χ² = 4.06, p < 0.05. U. urealyticum was predominant bacterial species found in 62.79% of isolates in the PROM cases, while in 32.56% it was isolated alone. Among the 49 pregnant women with preterm delivery, pPROM occurred in 29 (59.18% examinees, and in 70.83% of pregnant women with findings of high-density U. urealyticum pPROM was observed. Conclusion. Cervical colonization with U

  20. High Density Thermal Energy Storage with Supercritical Fluids

    Science.gov (United States)

    Ganapathi, Gani B.; Wirz, Richard

    2012-01-01

    A novel approach to storing thermal energy with supercritical fluids is being investigated, which if successful, promises to transform the way thermal energy is captured and utilized. The use of supercritical fluids allows cost-affordable high-density storage with a combination of latent heat and sensible heat in the two-phase as well as the supercritical state. This technology will enhance penetration of several thermal power generation applications and high temperature water for commercial use if the overall cost of the technology can be demonstrated to be lower than the current state-of-the-art molten salt using sodium nitrate and potassium nitrate eutectic mixtures.

  1. Areal density optimizations for heat-assisted magnetic recording of high-density media

    Science.gov (United States)

    Vogler, Christoph; Abert, Claas; Bruckner, Florian; Suess, Dieter; Praetorius, Dirk

    2016-06-01

    Heat-assisted magnetic recording (HAMR) is hoped to be the future recording technique for high-density storage devices. Nevertheless, there exist several realization strategies. With a coarse-grained Landau-Lifshitz-Bloch model, we investigate in detail the benefits and disadvantages of a continuous and pulsed laser spot recording of shingled and conventional bit-patterned media. Additionally, we compare single-phase grains and bits having a bilayer structure with graded Curie temperature, consisting of a hard magnetic layer with high TC and a soft magnetic one with low TC, respectively. To describe the whole write process as realistically as possible, a distribution of the grain sizes and Curie temperatures, a displacement jitter of the head, and the bit positions are considered. For all these cases, we calculate bit error rates of various grain patterns, temperatures, and write head positions to optimize the achievable areal storage density. Within our analysis, shingled HAMR with a continuous laser pulse moving over the medium reaches the best results and thus has the highest potential to become the next-generation storage device.

  2. Path to Efficient Lower Hybrid Current Drive at High Density

    Science.gov (United States)

    Baek, S. G.; Bonoli, P. T.; Brunner, D.; Faust, I.; Labombard, B. L.; Parker, R. R.; Shiraiwa, S.; Wallace, G. M.; Wukitch, S.

    2015-11-01

    Recovery of lower hybrid current drive (LHCD) efficiency at high density was demonstrated on Alcator C-Mod by modifying the scrape-off layer (SOL) plasma. RF probe measurements around the C-Mod tokamak indicate that the LH wave amplitude at the high field side wall significantly attenuates with plasma density. This is interpreted as enhanced collisional loss due to the increase in the SOL density and width. By taking advantage of the narrower SOL width by doubling plasma current to 1.1 MA, it is found that the LH wave amplitude maintains its strength, and an effective current drive is extended to above 1x10e20 m-3. An order of magnitude increase in non-thermal Bremsstrahlung emission is consistent with ray-tracing results which take into account the change of SOL profiles with current. In the coming campaign, a further investigation on the role of the SOL plasma is planned by raising plasma current above 1.1 MA. This will be aided with newly developed RF magnetic loop antennas mounted on a radially movable probe head. This system is expected to intercept the LH resonance cone on the first pass, allowing us to measure radial profiles of both the wave amplitude and dominant parallel wavenumber in the SOL for the first time. These data will be compared with the GENRAY ray-tracing code. Work supported by USDoE awards DE-FC02-99ER54512.

  3. Patterned Platinum Etching Studies in an Argon High Density Plasma

    Science.gov (United States)

    Delprat, Sébastien; Chaker, Mohamed; Margot, Joëlle; Pépin, Henri; Tan, Liang; Smy, Tom

    1998-10-01

    A high-density surface-wave Ar plasma operated in the low pressure regime is used to study pure physical etching characteristics of platinum thin films. The platinum samples are RF biased so as to obtain a maximum DC self-bias voltage of 150 V. The sputter-etching characteristics are investigated as a function of the magnetic field intensity, the self-bias voltage and the gas pressure. At 1 mtorr, the etch rate is found to be a unique linear function of both the self-bias voltage and the ion density, independently of the magnetic field intensity value. However, even though the ion density increases, the etch rate is found to decrease with increasing pressure. In the low pressure regime, etch rates as high as 2000 A/min are obtained with a good selectivity over resist. Without any optimization of the etching process, we were able to etch 0.5 micron Pt trenches, 0.6 micron thick yielding fence-free profiles and sidewall angles (75º) that already meets the present industrial requirements of NVRAM technology.

  4. Manipulating charge density waves in 1 T -TaS2 by charge-carrier doping: A first-principles investigation

    Science.gov (United States)

    Shao, D. F.; Xiao, R. C.; Lu, W. J.; Lv, H. Y.; Li, J. Y.; Zhu, X. B.; Sun, Y. P.

    2016-09-01

    The transition-metal dichalcogenide 1 T -TaS2 exhibits a rich set of charge-density-wave (CDW) orders. Recent investigations suggested that using light or an electric field can manipulate the commensurate CDW (CCDW) ground state. Such manipulations are considered to be determined by charge-carrier doping. Here we use first-principles calculations to simulate the carrier-doping effect on the CCDW in 1 T -TaS2 . We investigate the charge-doping effects on the electronic structures and phonon instabilities of the 1 T structure, and we analyze the doping-induced energy and distortion ratio variations in the CCDW structure. We found that both in bulk and monolayer 1 T -TaS2 , the CCDW is stable upon electron doping, while hole doping can significantly suppress the CCDW, implying different mechanisms of such reported manipulations. Light or positive perpendicular electric-field-induced hole doping increases the energy of the CCDW, so that the system transforms to a nearly commensurate CDW or a similar metastable state. On the other hand, even though the CCDW distortion is more stable upon in-plane electric-field-induced electron injection, some accompanied effects can drive the system to cross over the energy barrier from the CCDW to a nearly commensurate CDW or a similar metastable state. We also estimate that hole doping can introduce potential superconductivity with a Tc of 6-7 K. Controllable switching of different states such as a CCDW/Mott insulating state, a metallic state, and even a superconducting state can be realized in 1 T -TaS2 . As a result, this material may have very promising applications in future electronic devices.

  5. High Power Density Power Electronic Converters for Large Wind Turbines

    DEFF Research Database (Denmark)

    Senturk, Osman Selcuk

    In large wind turbines (in MW and multi-MW ranges), which are extensively utilized in wind power plants, full-scale medium voltage (MV) multi-level (ML) voltage source converters (VSCs) are being more preferably employed nowadays for interfacing these wind turbines with electricity grids...... assessments of these specific VSCs so that their power densities and reliabilities are quantitatively determined, which requires extensive utilization of the electro-thermal models of the VSCs under investigation. In this thesis, the three-level neutral-point-clamped VSCs (3L-NPC-VSCs), which are classified......-HB-VSCs). As the switch technology for realizing these 3L-VSCs, press-pack IGBTs are chosen to ensure high power density and reliability. Based on the selected 3L-VSCs and switch technology, the converter electro-thermal models are developed comprehensively, implemented practically, and validated via a full-scale 3L...

  6. Calcium isotopic composition of high-latitude proxy carrier Neogloboquadrina pachyderma (sin.

    Directory of Open Access Journals (Sweden)

    A. Eisenhauer

    2009-01-01

    Full Text Available The accurate reconstruction of sea surface temperature (SST history in climate-sensitive regions (e.g. tropical and polar oceans became a challenging task in palaeoceanographic research. Biogenic shell carbonate SST proxies successfully developed for tropical regions often fail in cool water environments. Their major regional shortcomings and the cryptic diversity now found within the major high latitude proxy carrier Neogloboquadrina pachyderma (sin. highlight an urgent need to explore complementary SST proxies for these cool-water regions. Here we incorporate the genetic component into a calibration study of a new SST proxy for the high latitudes. We found that the calcium isotopic composition (δ44/40Ca of calcite from genotyped net catches and core-top samples of the planktonic foraminifera Neogloboquadrina pachyderma (sin. is related to temperature and unaffected by genetic variations. The temperature sensitivity has been found to be 0.17 (±0.02‰ per 1°C, highlighting its potential for downcore applications in open marine cool-water environments. Our results further indicate that in extreme polar environments, below a critical threshold temperature of 2.0 (±0.5°C associated with salinities below 33.0 (±0.5‰, a prominent shift in biomineralization affects the δ44/40Ca of genotyped and core-top N. pachyderma (sin., becoming insensitive to temperature. These findings highlight the need of more systematic calibration studies on single planktonic foraminiferal species in order to unravel species-specific factors influencing the temperature sensitivity of Ca isotope fractionation and to validate the proxies' applicability.

  7. Microelectromechanical high-density energy storage/rapid release system

    Science.gov (United States)

    Rodgers, M. Steven; Allen, James J.; Meeks, Kent D.; Jensen, Brian D.; Miller, Samuel L.

    1999-08-01

    One highly desirable characteristic of electrostatically driven microelectromechanical systems (MEMS) is that they consume very little power. The corresponding drawback is that the force they produce may be inadequate for many applications. It has previously been demonstrated that gear reduction units or microtransmissions can substantially increase the torque generated by microengines. Operating speed, however, is also reduced by the transmission gear ratio. Some applications require both high speed and high force. If this output is only required for a limited period of time, then energy could be stored in a mechanical system and rapidly released upon demand. We have designed, fabricated, and demonstrated a high-density energy storage/rapid release system that accomplishes this task. Built using a 5-level surface micromachining technology, the assembly closely resembles a medieval crossbow. Energy releases on the order of tens of nanojoules have already been demonstrated, and significantly higher energy systems are under development.

  8. Toward Low-Cost, High-Energy Density, and High-Power Density Lithium-Ion Batteries

    Science.gov (United States)

    Li, Jianlin; Du, Zhijia; Ruther, Rose E.; AN, Seong Jin; David, Lamuel Abraham; Hays, Kevin; Wood, Marissa; Phillip, Nathan D.; Sheng, Yangping; Mao, Chengyu; Kalnaus, Sergiy; Daniel, Claus; Wood, David L.

    2017-06-01

    Reducing cost and increasing energy density are two barriers for widespread application of lithium-ion batteries in electric vehicles. Although the cost of electric vehicle batteries has been reduced by 70% from 2008 to 2015, the current battery pack cost (268/kWh in 2015) is still >2 times what the USABC targets (125/kWh). Even though many advancements in cell chemistry have been realized since the lithium-ion battery was first commercialized in 1991, few major breakthroughs have occurred in the past decade. Therefore, future cost reduction will rely on cell manufacturing and broader market acceptance. This article discusses three major aspects for cost reduction: (1) quality control to minimize scrap rate in cell manufacturing; (2) novel electrode processing and engineering to reduce processing cost and increase energy density and throughputs; and (3) material development and optimization for lithium-ion batteries with high-energy density. Insights on increasing energy and power densities of lithium-ion batteries are also addressed.

  9. Toward Low-Cost, High-Energy Density, and High-Power Density Lithium-Ion Batteries

    Science.gov (United States)

    Li, Jianlin; Du, Zhijia; Ruther, Rose E.; AN, Seong Jin; David, Lamuel Abraham; Hays, Kevin; Wood, Marissa; Phillip, Nathan D.; Sheng, Yangping; Mao, Chengyu; Kalnaus, Sergiy; Daniel, Claus; Wood, David L.

    2017-09-01

    Reducing cost and increasing energy density are two barriers for widespread application of lithium-ion batteries in electric vehicles. Although the cost of electric vehicle batteries has been reduced by 70% from 2008 to 2015, the current battery pack cost (268/kWh in 2015) is still >2 times what the USABC targets (125/kWh). Even though many advancements in cell chemistry have been realized since the lithium-ion battery was first commercialized in 1991, few major breakthroughs have occurred in the past decade. Therefore, future cost reduction will rely on cell manufacturing and broader market acceptance. This article discusses three major aspects for cost reduction: (1) quality control to minimize scrap rate in cell manufacturing; (2) novel electrode processing and engineering to reduce processing cost and increase energy density and throughputs; and (3) material development and optimization for lithium-ion batteries with high-energy density. Insights on increasing energy and power densities of lithium-ion batteries are also addressed.

  10. Multifractal analysis of high resolution solar wind proton density measurements

    Science.gov (United States)

    Sorriso-Valvo, Luca; Carbone, Francesco; Leonardis, Ersilia; Chen, Christopher H. K.; Šafránková, Jana; Němeček, Zdenek

    2017-03-01

    The solar wind is a highly turbulent medium, with a high level of field fluctuations throughout a broad range of scales. These include an inertial range where a turbulent cascade is assumed to be active. The solar wind cascade shows intermittency, which however may depend on the wind conditions. Recent observations have shown that ion-scale magnetic turbulence is almost self-similar, rather than intermittent. A similar result was observed for the high resolution measurements of proton density provided by the spacecraft Spektr-R. Intermittency may be interpreted as the result of the multifractal properties of the turbulent cascade. In this perspective, this paper is devoted to the description of the multifractal properties of the high resolution density measurements. In particular, we have used the standard coarse-graining technique to evaluate the generalized dimensions Dq , and from these the multifractal spectrum f (α) , in two ranges of scale. A fit with the p-model for intermittency provided a quantitative measure of multifractality. Such indicator was then compared with alternative measures: the width of the multifractal spectrum, the peak of the kurtosis, and its scaling exponent. The results indicate that the small-scale fluctuations are multifractal, and suggest that different measures of intermittency are required to fully understand the small scale cascade.

  11. Ultra-Stretchable Interconnects for High-Density Stretchable Electronics

    Directory of Open Access Journals (Sweden)

    Salman Shafqat

    2017-09-01

    Full Text Available The exciting field of stretchable electronics (SE promises numerous novel applications, particularly in-body and medical diagnostics devices. However, future advanced SE miniature devices will require high-density, extremely stretchable interconnects with micron-scale footprints, which calls for proven standardized (complementary metal-oxide semiconductor (CMOS-type process recipes using bulk integrated circuit (IC microfabrication tools and fine-pitch photolithography patterning. Here, we address this combined challenge of microfabrication with extreme stretchability for high-density SE devices by introducing CMOS-enabled, free-standing, miniaturized interconnect structures that fully exploit their 3D kinematic freedom through an interplay of buckling, torsion, and bending to maximize stretchability. Integration with standard CMOS-type batch processing is assured by utilizing the Flex-to-Rigid (F2R post-processing technology to make the back-end-of-line interconnect structures free-standing, thus enabling the routine microfabrication of highly-stretchable interconnects. The performance and reproducibility of these free-standing structures is promising: an elastic stretch beyond 2000% and ultimate (plastic stretch beyond 3000%, with <0.3% resistance change, and >10 million cycles at 1000% stretch with <1% resistance change. This generic technology provides a new route to exciting highly-stretchable miniature devices.

  12. High Density Culture of Porphyridium cruentum in a 42 L Internal Airlift Loop Photobioreactor

    Institute of Scientific and Technical Information of China (English)

    王长海; 王逸云; 田志立

    2003-01-01

    The key limiting factors to high-density culture of Porphyridium cruentum are the uptake of light energy and nutrient by the microalgal cells. Under the optimal conditions of carrier culture, both cell mass and cell density were increased significantly up to 5.2 g/L (DW) and 5.2×107/ml. Furthermore,the effects of the liquid circulation velocity, light intensity and initial cell density on cell mass productivity of P. cruentum were investigated in a 42 L internal loop airlift photobioreactor. Although the light intensity was as low as 100 μmol/(m2@s), the light damage or the photoinhibition phenomenon was observed under the culture condition of low initial cell mass (0.10 g/L, DW) and high liquid circulation velocity (0.30 m/s). However, a higher cell growth rate and a high cell mass productivity were achieved with the same conditions only at high initial cell mass (about 0.80 g/L, DW). Under the optimal conditions, the cell specific growth rate, cell mass volumetric and areal output rate reached to 0.95 d-1,0.80 g/(L@d) and 42.5 g/(m2@d) respectively. Finally, a method of nutrient feeding and gradual increase of light intensity in different cultural stages was developed, which further improved the cell mass, cell mass volumetric and areal output rate to 5.9 g/L, 1.2 g/(L@d) and 61.7 g/(m2@d) respectively.

  13. Recycling Gene Carrier with High Efficiency and Low Toxicity Mediated by L-Cystine-Bridged Bis(β-cyclodextrin)s

    Science.gov (United States)

    Zhang, Yu-Hui; Chen, Yong; Zhang, Ying-Ming; Yang, Yang; Chen, Jia-Tong; Liu, Yu

    2014-12-01

    Constructing safe and effective gene delivery carriers is becoming highly desirable for gene therapy. Herein, a series of supramolecular crosslinking system were prepared through host-guest binding of adamantyl-modified low molecular weight of polyethyleneimine with L-cystine-bridged bis(β-cyclodextrin)s and characterized by 1H NMR titration, electron microscopy, zeta potential, dynamic light-scattering, gel electrophoresis, flow cytometry and confocal fluorescence microscopy. The results showed that these nanometersized supramolecular crosslinking systems exhibited higher DNA transfection efficiencies and lower cytotoxicity than the commercial DNA carrier gold standard (25 kDa bPEI) for both normal cells and cancer cells, giving a very high DNA transfection efficiency up to 54% for 293T cells. Significantly, this type of supramolecular crosslinking system possesses a number of enzyme-responsive disulfide bonds, which can be cleaved by reductive enzyme to promote the DNA release but recovered by oxidative enzyme to make the carrier renewable. These results demonstrate that these supramolecular crosslinking systems can be used as promising gene carriers.

  14. Pistachio intake increases high density lipoprotein levels and inhibits low-density lipoprotein oxidation in rats.

    Science.gov (United States)

    Aksoy, Nur; Aksoy, Mehmet; Bagci, Cahit; Gergerlioglu, H Serdar; Celik, Hakim; Herken, Emine; Yaman, Abdullah; Tarakcioglu, Mehmet; Soydinc, Serdar; Sari, Ibrahim; Davutoglu, Vedat

    2007-05-01

    There is increasing evidence that nuts have protective effects against coronary artery disease by improving lipid profile and inhibiting lipid oxidation. However, data about pistachio nuts are limited, and to our knowledge, there is no study investigating the effects of pistachio intake on lipid oxidation and serum antioxidant levels. This study, therefore, sought to determine the effects of pistachio intake on serum lipids and determine whether consumption of pistachio would alter serum antioxidant levels. Rats were randomly divided into three groups (n=12 for each): control group fed basic diet for 10 weeks and treated groups fed basic diet plus pistachio which constituted 20% and 40% of daily caloric intake, respectively. Consumption of pistachio as 20% of daily caloric intake increased high-density lipoprotein (HDL) levels and decreased total cholesterol (TC)/HDL ratio, compared with those not taking pistachio. However, TC, low-density lipoprotein (LDL) cholesterol and triglyceride levels were unaffected by pistachio consumption. Consumption of pistachio as 20% of daily caloric intake increased serum paraoxonase activity by 35% and arylesterase activity by 60%, which are known to inhibit LDL cholesterol oxidation, compared with the control group. However, increased antioxidant activity was blunted when pistachio intake was increased to 40% of daily caloric intake. In conclusion, the present results show that consumption of pistachio as 20% of daily caloric intake leads to significant improvement in HDL and TC/HDL ratio and inhibits LDL cholesterol oxidation. These results suggest that pistachio may be beneficial for both prevention and treatment of coronary artery disease.

  15. High energy density capacitors using nano-structure multilayer technology

    Energy Technology Data Exchange (ETDEWEB)

    Barbee, T.W. Jr.; Johnson, G.W.; O`Brien, D.W.

    1992-08-01

    Today, many pulse power and industrial applications are limited by capacitor performance. While incremental improvements are anticipated from existing capacitor technologies, significant advances are needed in energy density to enable these applications for both the military and for American economic competitiveness. We propose a program to research and develop a novel technology for making high voltage, high energy density capacitors. Nano-structure multilayer technologies developed at LLNL may well provide a breakthrough in capacitor performance. Our controlled sputtering techniques are capable of laying down extraordinarily smooth sub-micron layers of dielectric and conductor materials. With this technology, high voltage capacitors with an order of magnitude improvement in energy density may be achievable. Well-understood dielectrics and new materials will be investigated for use with this technology. Capacitors developed by nano-structure multilayer technology are inherently solid state, exhibiting extraordinary mechanical and thermal properties. The conceptual design of a Notepad capacitor is discussed to illustrate capacitor and capacitor bank design and performance with this technology. We propose a two phase R&D program to address DNA`s capacitor needs for electro-thermal propulsion and similar pulse power programs. Phase 1 will prove the concept and further our understanding of dielectric materials and design tradeoffs with multilayers. Nano-structure multilayer capacitors will be developed and characterized. As our materials research and modeling prove successful, technology insertion in our capacitor designs will improve the possibility for dramatic performance improvements. In Phase 2, we will make Notepad capacitors, construct a capacitor bank and demonstrate its performance in a meaningful pulse power application. We will work with industrial partners to design full scale manufacturing and move this technology to industry for volume production.

  16. The Pulsed High Density Experiment (PHDX) Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Slough, John P. [Univ. of Washington, Seattle, WA (United States); Andreason, Samuel [Univ. of Washington, Seattle, WA (United States)

    2017-04-27

    The purpose of this paper is to present the conclusions that can be drawn from the Field Reversed Configuration (FRC) formation experiments conducted on the Pulsed High Density experiment (PHD) at the University of Washington. The experiment is ongoing. The experimental goal for this first stage of PHD was to generate a stable, high flux (>10 mWb), high energy (>10 KJ) target FRC. Such results would be adequate as a starting point for several later experiments. This work focuses on experimental implementation and the results of the first four month run. Difficulties were encountered due to the initial on-axis plasma ionization source. Flux trapping with this ionization source acting alone was insufficient to accomplish experimental objectives. Additional ionization methods were utilized to overcome this difficulty. A more ideal plasma source layout is suggested and will be explored during a forthcoming work.

  17. High fructose intake fails to induce symptomatic adaptation but may induce intestinal carriers

    Directory of Open Access Journals (Sweden)

    Debra Heilpern

    2010-01-01

    Full Text Available Fructose has several interactions in man, including intolerance and promotion of some diseases. However, fructose in fruits and in prebiotics may be associated with benefits. Adaptation to regular fructose ingestion as defined for lactose could support a beneficial rather than a deleterious effect. This study was undertaken to evaluate symptomatic response and potential underlying mechanisms of fecal bacterial change and breath hydrogen response to short term regular fructose supplementation. Forty-five participants were recruited for a 3 day recall diet questionnaire and a 50 g fructose challenge. Breath hydrogen was measured for 4.5 hrs and symptoms were recorded. Thirty-eight subjects provided stool samples for analysis by selective culture of 4 groups of bacteria, including bifidobacteria and lactobacilli. Intolerant subjects returned a second time 15 days later. Ten of these served as controls and 16 received 30 g fructose twice a day. Ten of the latter returned 27 days later, after stopping fructose for a third challenge test. Student’s paired, unpaired t-tests and Pearson correlations were used. Significance was accepted at P<0.05. After fructose rechallenge there were no significant reductions in symptoms scores in volunteers in either the fructose supplemented or non supplemented groups. However, total breath hydrogen was reduced between test 1 and test 2 (P=0.03 or test 3 (P=0.04 in the group given fructose then discontinued, compared with controls. There were no statistically significant changes in bacterial numbers between test 2 and 1. This study shows that regular consumption of high dose fructose does not follow the lactose model of adaptation. Observed changes in hydrogen breath tests raise the possibility that intestinal carriers of fructose may be induced potentially aggravating medical problems attributed to fructose.

  18. Introduction of high nitrogen doped graphene as a new cationic carrier in electromembrane extraction.

    Science.gov (United States)

    Atarodi, Atefe; Chamsaz, Mahmoud; Moghaddam, Ali Zeraatkar; Tabani, Hadi

    2016-05-01

    This paper proposes for the first time, the use of high nitrogen doped graphene (HND-G) as a new cationic carrier for the enhancement of electromembrane extraction (EME) performance. Sensitivity of EME was improved by the modification of supported liquid membrane composition through the addition of HND-G into 1-octanol for the extraction of naproxen and sodium diclofenac as model acidic drugs. The comparison between HND-G-modified EME and conventional EME showed that HND-G could increase the overall partition coefficient of acidic drugs in the membrane due to the fact that HND-G acts as an ion pair reagent and there is an electrostatic interaction between positively charged HND-G and acidic drugs with negative charge. During the extraction, model acidic drugs migrated from a 10 mL aqueous sample solution (pH 9.6) through a thin layer of 1-octanol containing 0.6% w/v of HND-G that was impregnated in the pores of a hollow fiber, into a 30 μL basic aqueous acceptor solution (pH 12.3) present in the lumen of the hollow fiber. Equilibrium extraction conditions were obtained after 16 min of operation with the whole assembly agitated at 1000 rpm. Under the optimized conditions, the enrichment factors were between 238 and 322 and also the LODs ranged from 0.1 to 0.7 ng/mL in different samples. Finally, the applicability of this method was evaluated by the extraction and determination of drugs of interest in real urine samples. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. [Residual risk: The roles of triglycerides and high density lipoproteins].

    Science.gov (United States)

    Grammer, Tanja; Kleber, Marcus; Silbernagel, Günther; Scharnagl, Hubert; März, Winfried

    2016-06-01

    In clinical trials, the reduction of LDL-cholesterol (LDL-C) with statins reduces the incidence rate of cardiovascular events by approximately one third. This means, that a sizeable "residual risk" remains. Besides high lipoprotein (a), disorders in the metabolism of triglyceride-rich lipoproteins and high density liproteins have been implicated as effectors of the residual risk. Both lipoprotein parameters correlate inversely with each other. Therefore, the etiological contributions of triglycerides and / or of HDL for developing cardiovascular disease can hardly be estimated from either observational studies or from intervention studies. The largely disappointing results of intervention studies with inhibitors of the cholesteryl ester transfer protein and in particular the available set of genetically-epidemiological studies suggest that in the last decade, the importance of HDL cholesterol has been overvalued, while the importance of triglycerides has been underestimated. High triglycerides not always atherogenic, but only if they are associated with the accumulation relatively cholesterol-enriched, incompletely catabolized remnants of chylomicrons and very low density lipoproteins (familial type III hyperlipidemia, metabolic syndrome, diabetes mellitus). The normalization of the concentration of triglycerides and remnants by inhibiting the expression of apolipoprotein C3 is hence a new, promising therapeutic target.

  20. Metal hydrides based high energy density thermal battery

    Energy Technology Data Exchange (ETDEWEB)

    Fang, Zhigang Zak, E-mail: zak.fang@utah.edu [Department of Metallurgical Engineering, The University of Utah, 135 South 1460 East, Room 412, Salt Lake City, UT 84112-0114 (United States); Zhou, Chengshang; Fan, Peng [Department of Metallurgical Engineering, The University of Utah, 135 South 1460 East, Room 412, Salt Lake City, UT 84112-0114 (United States); Udell, Kent S. [Department of Metallurgical Engineering, The University of Utah, 50 S. Central Campus Dr., Room 2110, Salt Lake City, UT 84112-0114 (United States); Bowman, Robert C. [Department of Metallurgical Engineering, The University of Utah, 135 South 1460 East, Room 412, Salt Lake City, UT 84112-0114 (United States); Vajo, John J.; Purewal, Justin J. [HRL Laboratories, LLC, 3011 Malibu Canyon Road, Malibu, CA 90265 (United States); Kekelia, Bidzina [Department of Metallurgical Engineering, The University of Utah, 50 S. Central Campus Dr., Room 2110, Salt Lake City, UT 84112-0114 (United States)

    2015-10-05

    Highlights: • The principle of the thermal battery using advanced metal hydrides was demonstrated. • The thermal battery used MgH{sub 2} and TiMnV as a working pair. • High energy density can be achieved by the use of MgH{sub 2} to store thermal energy. - Abstract: A concept of thermal battery based on advanced metal hydrides was studied for heating and cooling of cabins in electric vehicles. The system utilized a pair of thermodynamically matched metal hydrides as energy storage media. The pair of hydrides that was identified and developed was: (1) catalyzed MgH{sub 2} as the high temperature hydride material, due to its high energy density and enhanced kinetics; and (2) TiV{sub 0.62}Mn{sub 1.5} alloy as the matching low temperature hydride. Further, a proof-of-concept prototype was built and tested, demonstrating the potential of the system as HVAC for transportation vehicles.

  1. A New Hard Switching Bidirectional Converter With High Power Density

    Directory of Open Access Journals (Sweden)

    Bahador Fani

    2010-01-01

    Full Text Available In this paper, a new isolated dc-dc bidirectional converter is proposed. This converter consists of two transformers (flyback and forward and only one switch in primary side and one switch in secondary side of transformers. In this converter energy transfers to the output in both on and off switch states so power density of this converter is high This converter controlled by PWM signal. Also this converter operates over a wide input voltage range. Theoretical analysis is presented and computer simulation and experimental results verify the converter analysis.

  2. On high-order perturbative calculations at finite density

    CERN Document Server

    Ghisoiu, Ioan

    2017-01-01

    We discuss the prospects of performing high-order perturbative calculations in systems characterized by a vanishing temperature but finite density. In particular, we show that the determination of generic Feynman integrals containing fermionic chemical potentials can be reduced to the evaluation of three-dimensional phase space integrals over vacuum on-shell amplitudes. Applications of these rules will be discussed in the context of the thermodynamics of cold and dense QCD, where it is argued that they facilitate an extension of the Equation of State of cold quark matter to higher perturbative orders.

  3. On high-order perturbative calculations at finite density

    Science.gov (United States)

    Ghişoiu, Ioan; Gorda, Tyler; Kurkela, Aleksi; Romatschke, Paul; Säppi, Matias; Vuorinen, Aleksi

    2017-02-01

    We discuss the prospects of performing high-order perturbative calculations in systems characterized by a vanishing temperature but finite density. In particular, we show that the determination of generic Feynman integrals containing fermionic chemical potentials can be reduced to the evaluation of three-dimensional phase space integrals over vacuum on-shell amplitudes - a result reminiscent of a previously proposed "naive real-time formalism" for vacuum diagrams. Applications of these rules are discussed in the context of the thermodynamics of cold and dense QCD, where it is argued that they facilitate an extension of the Equation of State of cold quark matter to higher perturbative orders.

  4. Ultra High Energy Density Cathodes with Carbon Nanotubes

    Science.gov (United States)

    2013-12-10

    34Enhanced Capacity and Rate Capability of Carbon Nanotube Based Anodes with Titanium Contacts for Lithium Ion Batteries," ACS Nano, vol. 4, pp. 6121- 6131...2010/10/26 2010. [2] S. L. Chou, et al., "Silicon/Single-Walled Carbon Nanotube Composite Paper as a Flexible Anode Material for Lithium Ion...AFRL-RV-PS- AFRL-RV-PS- TR-2013-0170 TR-2013-0170 ULTRA HIGH ENERGY DENSITY CATHODES WITH CARBON NANOTUBES Brian J. Landi, et al. Rochester

  5. High density QCD and entropy production at heavy ion colliders

    CERN Document Server

    Kinder-Geiger, Klaus

    1994-01-01

    The role of entropy production in the context of probing QCD properties at high densities and finite temperatures in ultra-relativistic collisions of heavy nuclei is inspected. It is argued that the entropy generated in these reactions provides a powerful tool to investigate the space-time evolution and the question whether and how a deconfined plasma of quarks and gluons is formed. I will address the questions how entropy is produced, and how it is measurable. The uncertainties in predicting the different contributions to the total entropy and particle multiplicities during the course of heavy ion collisions are also discussed.

  6. Method for providing a low density high strength polyurethane foam

    Science.gov (United States)

    Whinnery, Jr., Leroy L.; Goods, Steven H.; Skala, Dawn M.; Henderson, Craig C.; Keifer, Patrick N.

    2013-06-18

    Disclosed is a method for making a polyurethane closed-cell foam material exhibiting a bulk density below 4 lbs/ft.sup.3 and high strength. The present embodiment uses the reaction product of a modified MDI and a sucrose/glycerine based polyether polyol resin wherein a small measured quantity of the polyol resin is "pre-reacted" with a larger quantity of the isocyanate in a defined ratio such that when the necessary remaining quantity of the polyol resin is added to the "pre-reacted" resin together with a tertiary amine catalyst and water as a blowing agent, the polymerization proceeds slowly enough to provide a stable foam body.

  7. The physics of ultra-high-density magnetic recording

    CERN Document Server

    Ek, Johannes; Weller, Dieter

    2001-01-01

    In this book, 17 experts in magnetic recording focus on the underlying physical mechanisms that play crucial roles in medium and transducer development for high areal density disk drives. In 11 chapters, an examination is made of the fundamental physical concepts and their impact on recording mechanisms, with special emphasis on thin-film longitudinal, perpendicular, patterned and nanoparticle media. Theoretical and experimental investigations are presented which serve to enhance our basic understanding of thin-film dynamics, medium dynamics and thermal effects. Fundamental aspects of magnetotransport are discussed and an overview is given of recording head designs.

  8. Antarctic marine gravity field from high-density satellite altimetry

    Science.gov (United States)

    Sandwell, David T.

    1992-01-01

    High-density (about 2-km profile spacing) Geosat/GM altimetry profiles were obtained for Antarctic waters (6-deg S to 72 deg S) and converted to vertical gravity gradient, using Laplace's equation to directly calculate gravity gradient from vertical deflection grids and Fourier analysis to construct gravity anomalies from two vertical deflection grids. The resultant gravity grids have resolution and accuracy comparable to shipboard gravity profiles. The obtained gravity maps display many interesting and previously uncharted features, such as a propagating rift wake and a large 'leaky transform' along the Pacific-Antarctic Rise.

  9. A Cherenkov Radiation Detector with High Density Aerogels

    CERN Document Server

    Cremaldi, Lucien; Sonnek, Peter; Summers, Donald J; Reidy, Jim

    2009-01-01

    We have designed a threshold Cherenkov detector at the Rutherford-Appleton Laboratory to identify muons with momenta between 230 and 350 MeV/c. We investigated the properties of three aerogels for the design. The nominal indexes of refraction were n = 1.03, 1.07, 1.12, respectively. Two of the samples are of high density aerogel not commonly used for Cherenkov light detection. We present results of an examination of some optical properties of the aerogel samples and present basic test beam results.

  10. Biomimetic High Density Lipoprotein Nanoparticles For Nucleic Acid Delivery

    Science.gov (United States)

    McMahon, Kaylin M.; Mutharasan, R. Kannan; Tripathy, Sushant; Veliceasa, Dorina; Bobeica, Mariana; Shumaker, Dale K.; Luthi, Andrea J.; Helfand, Brian T.; Ardehali, Hossein; Mirkin, Chad A.; Volpert, Olga; Thaxton, C. Shad

    2014-01-01

    We report a gold nanoparticle-templated high density lipoprotein (HDL AuNP) platform for gene therapy which combines lipid-based nucleic acid transfection strategies with HDL biomimicry. For proof-of-concept, HDL AuNPs are shown to adsorb antisense cholesterylated DNA. The conjugates are internalized by human cells, can be tracked within cells using transmission electron microscopy (TEM), and regulate target gene expression. Overall, the ability to directly image the AuNP core within cells, the chemical tailorability of the HDL AuNP platform, and the potential for cell-specific targeting afforded by HDL biomimicry make this platform appealing for nucleic acid delivery. PMID:21319839

  11. Transmutation of minor actinides discharged from LMFBR spent fuel in a high power density fusion reactor

    Energy Technology Data Exchange (ETDEWEB)

    Uebeyli, Mustafa E-mail: mubeyli@gazi.edu.tr

    2004-12-01

    Significant amounts of nuclear wastes consisting of plutonium, minor actinides and long lived fission products are produced during the operation of commercial nuclear power plants. Therefore, the destruction of these wastes is very important with respect to public health, environment and also the future of nuclear energy. In this study, transmutation of minor actinides (MAs) discharged from LMFBR spent fuel in a high power density fusion reactor has been investigated under a neutron wall load of 10 MW/m{sup 2} for an operation period of 10 years. Also, the effect of MA percentage on the transmutation has been examined. The fuel zone, containing MAs as spheres cladded with W-5Re, has been located behind the first wall to utilize the high neutron flux for transmutation effectively. Helium at 40 atm has been used as an energy carrier. At the end of the operation period, the total burning and transmutation are greater than the total buildups in all investigated cases, and very high burnups (420-470 GWd/tHM) are reached, depending on the MA content. The total transmutation rate values are 906 and 979 kg/GW{sub th} year at startup and decrease to 140 and 178 kg/GW{sub th} year at the end of the operation for fuel with 10% and 20% MA, respectively. Over an operation period of 10 years, the effective half lives decrease from 2.38, 2.21 and 3.08 years to 1.95, 1.80 and 2.59 years for {sup 237}Np, {sup 241}Am and {sup 243}Am, respectively. Total atomic densities decrease exponentially during the operation period. The reductions in the total atomic densities with respect to the initial ones are 79%, 81%, 82%, 83%, 85% and 86% for 10%, 12%, 14%, 16%, 18% and 20% MAs, respectively.

  12. Scalable Sub-micron Patterning of Organic Materials Toward High Density Soft Electronics.

    Science.gov (United States)

    Kim, Jaekyun; Kim, Myung-Gil; Kim, Jaehyun; Jo, Sangho; Kang, Jingu; Jo, Jeong-Wan; Lee, Woobin; Hwang, Chahwan; Moon, Juhyuk; Yang, Lin; Kim, Yun-Hi; Noh, Yong-Young; Jaung, Jae Yun; Kim, Yong-Hoon; Park, Sung Kyu

    2015-09-28

    The success of silicon based high density integrated circuits ignited explosive expansion of microelectronics. Although the inorganic semiconductors have shown superior carrier mobilities for conventional high speed switching devices, the emergence of unconventional applications, such as flexible electronics, highly sensitive photosensors, large area sensor array, and tailored optoelectronics, brought intensive research on next generation electronic materials. The rationally designed multifunctional soft electronic materials, organic and carbon-based semiconductors, are demonstrated with low-cost solution process, exceptional mechanical stability, and on-demand optoelectronic properties. Unfortunately, the industrial implementation of the soft electronic materials has been hindered due to lack of scalable fine-patterning methods. In this report, we demonstrated facile general route for high throughput sub-micron patterning of soft materials, using spatially selective deep-ultraviolet irradiation. For organic and carbon-based materials, the highly energetic photons (e.g. deep-ultraviolet rays) enable direct photo-conversion from conducting/semiconducting to insulating state through molecular dissociation and disordering with spatial resolution down to a sub-μm-scale. The successful demonstration of organic semiconductor circuitry promise our result proliferate industrial adoption of soft materials for next generation electronics.

  13. Trade-off between morphology, extended defects, and compositional fluctuation induced carrier localization in high In-content InGaN films

    Science.gov (United States)

    Ju, James Zi-Jian; Loitsch, Bernhard; Stettner, Thomas; Schuster, Fabian; Stutzmann, Martin; Koblmüller, Gregor

    2014-08-01

    We elucidate the role of growth parameters (III/N flux ratio, temperature TG) on the morphological and structural properties, as well as compositional homogeneity and carrier localization effects of high In-content (x(In) > 0.75) In-polar InGaN films grown by plasma-assisted molecular beam epitaxy (PAMBE). Variations in III/N flux ratio evidence that higher excess of In yields higher threading dislocation densities as well as larger compositional inhomogeneity as measured by x-ray diffraction. Most interestingly, by variation of growth temperature TG we find a significant trade-off between improved morphological quality and compositional homogeneity at low-TG (˜450-550 °C) versus improved threading dislocation densities at high-TG (˜600-630 °C), as exemplified for InGaN films with x(In) = 0.9. The enhanced compositional homogeneity mediated by low-TG growth is confirmed by systematic temperature-dependent photoluminescence (PL) spectroscopy data, such as lower PL peakwidths, >5× higher PL efficiency (less temperature-induced quenching) and a distinctly different temperature-dependent S-shape behavior of the PL peak energy. From these, we find that the carrier localization energy is as low as ˜20 meV for low-TG grown films (TG = 550 °C), while it rises to ˜70 meV for high-TG grown films (TG = 630 °C) right below the onset of In-N dissociation. These findings point out that for the kinetically limited metal-rich PAMBE growth of high In-content InGaN a III/N flux ratio of ˜1 and low-to-intermediate TG are required to realize optically more efficient materials.

  14. Biominetic High Density Lipoproteins for the Delivery of Therapeutic Oligonucleotides

    Science.gov (United States)

    Tripathy, Sushant

    Advances in nanotechnology have brought about novel inorganic and hybrid nanoparticles with unique physico-chemical properties that make them suitable for a broad range of applications---from nano-circuitry to drug delivery. A significant part of those advancements have led to ground-breaking discoveries that have changed the approaches to formulation of therapeutics against diseases, such as cancer. Now-a-days the focus does not lie solely on finding a candidate small-molecule therapeutic with minimal adverse effects, but researchers are looking up to nanoparticles to improve biodistribution and biocompatibility profile of clinically proven therapeutics. The plethora of conjugation chemistries offered by currently extant inorganic nanoparticles have, in recent years, led to great leaps in the field of biomimicry---a modality that promises high biocompatibility. Further, in the pursuit of highly specific therapeutic molecules, researchers have turned to silencing oligonucleotides and some have already brought together the strengths of nanoparticles and silencing oligonucleotides in search of an efficacious therapy for cancer with minimal adverse effects. This dissertation work focuses on such a biomimetic platform---a gold nanoparticle based high density lipoprotein biomimetic (HDL NP), for the delivery of therapeutic oligonucleotides. The first chapter of this body of work introduces the molecular target of the silencing oligonucleotides---VEGFR2, and its role in the progression of solid tumor cancers. The background information also covers important aspects of natural high density lipoproteins (HDL), especially their innate capacity to bind and deliver exogenous and endogenous silencing oligonucleotides to tissues that express their high affinity receptor SRB1. We subsequently describe the synthesis of the biomimetic HDL NP and its oligonucleotide conjugates, and establish their biocompatibility. Further on, experimental data demonstrate the efficacy of silencing

  15. A three-dimensional nitrogen-doped graphene structure: a highly efficient carrier of enzymes for biosensors.

    Science.gov (United States)

    Guo, Jingxing; Zhang, Tao; Hu, Chengguo; Fu, Lei

    2015-01-28

    In recent years, graphene-based enzyme biosensors have received considerable attention due to their excellent performance. Enormous efforts have been made to utilize graphene oxide and its derivatives as carriers of enzymes for biosensing. However, the performance of these sensors is limited by the drawbacks of graphene oxide such as slow electron transfer rate, low catalytic area and poor conductivity. Here, we report a new graphene-based enzyme carrier, i.e. a highly conductive 3D nitrogen-doped graphene structure (3D-NG) grown by chemical vapour deposition, for highly effective enzyme-based biosensors. Owing to the high conductivity, large porosity and tunable nitrogen-doping ratio, this kind of graphene framework shows outstanding electrical properties and a large surface area for enzyme loading and biocatalytic reactions. Using glucose oxidase (GOx) as a model enzyme and chitosan (CS) as an efficient molecular binder of the enzyme, our 3D-NG based biosensors show extremely high sensitivity for the sensing of glucose (226.24 μA mM(-1) m(-2)), which is almost an order of magnitude higher than those reported in most of the previous studies. The stable adsorption and outstanding direct electrochemical behaviour of the enzyme on the nanocomposite indicate the promising application of this 3D enzyme carrier in high-performance electrochemical biosensors or biofuel cells.

  16. Simulating deposition of high density tailings using smoothed particle hydrodynamics

    Science.gov (United States)

    Babaoglu, Yagmur; Simms, Paul H.

    2017-08-01

    Tailings are a slurry of silt-sized residual material derived from the milling of rock. High density (HD) tailings are tailings that have been sufficiently dewatered to a point where they exhibit a yield stress upon deposition. They form gently sloped stacks on the surface when deposited; this eliminates or minimizes the need for dams or embankments for containment. Understanding the flow behaviour of high density tailings is essential for estimating the final stack geometry and overall slope angle. This paper focuses on modelling the flow behaviour of HD tailings using smoothed particle hydrodynamics (SPH) method incorporating a `bi-viscosity' model to simulate the non-Newtonian behaviour. The model is validated by comparing the numerical results with bench scale experiments simulating single or multi-layer deposits in two-dimensions. The results indicate that the model agreed fairly well with the experimental work, excepting some repulsion of particles away from the bottom boundary closer to the toe of the deposits. Novel aspects of the work, compared to other simulation of Bingham fluids by SPH, are the simulation of multilayer deposits and the use of a stopping criteria to characterize the rest state.

  17. Multiple parton interactions in high-density QCD matter

    CERN Document Server

    Srivastava, D K; Srivastava, Dinesh K.; Geiger, Klaus

    1999-01-01

    Multiple interactions of quarks and gluons in high-energy heavy-ion collisions may give rise to interesting phemomena of color charges propagating in high-density QCD matter. We study the dynamics of multi-parton systems produced in nucleus-nucleus collisions at energies corresponding the the CERN SPS and the future BNL RHIC experiments. Due to the complexity of the multi-particle dynamics we choose to employ the parton cascade model in order to simulate the development of multiple parton scatterings and associated stimulated emision processes. Our results indicate a non-linear increase with nuclear mass A of, e.g., parton multiplicity, energy density, strangeness, and contrast a linear A-scaling as in Glauber-type approaches. If multiple interactions are suppressed and only single parton scatterings (no re-interactions) are considered, we recover such a linear behavior. It remains to be studied whether these results on the parton level can be experimentally seen in final-state observables, such as the charge...

  18. Development Status of High-Thrust Density Electrostatic Engines

    Science.gov (United States)

    Patterson, Michael J.; Haag, Thomas W.; Foster, John E.; Young, Jason A.; Crofton, Mark W.

    2017-01-01

    Ion thruster technology offers the highest performance and efficiency of any mature electric propulsion thruster. It has by far the highest demonstrated total impulse of any technology option, demonstrated at input power levels appropriate for primary propulsion. It has also been successfully implemented for primary propulsion in both geocentric and heliocentric environments, with excellent ground/in-space correlation of both its performance and life. Based on these attributes there is compelling reasoning to continue the development of this technology: it is a leading candidate for high power applications; and it provides risk reduction for as-yet unproven alternatives. As such it is important that the operational limitations of ion thruster technology be critically examined and in particular for its application to primary propulsion its capabilities relative to thrust the density and thrust-to-power ratio be understood. This publication briefly addresses some of the considerations relative to achieving high thrust density and maximizing thrust-to-power ratio with ion thruster technology, and discusses the status of development work in this area being executed under a collaborative effort among NASA Glenn Research Center, the Aerospace Corporation, and the University of Michigan.

  19. Strongly Interacting Matter at Very High Energy Density

    Energy Technology Data Exchange (ETDEWEB)

    McLerran, L.

    2011-06-05

    The authors discuss the study of matter at very high energy density. In particular: what are the scientific questions; what are the opportunities to makes significant progress in the study of such matter and what facilities are now or might be available in the future to answer the scientific questions? The theoretical and experimental study of new forms of high energy density matter is still very much a 'wild west' field. There is much freedom for developing new concepts which can have order one effects on the way we think about such matter. It is also a largely 'lawless' field, in that concepts and methods are being developed as new information is generated. There is also great possibility for new experimental discovery. Most of the exciting results from RHIC experiments were unanticipated. The methods used for studying various effects like flow, jet quenching, the ridge, two particle correlations etc. were developed as experiments evolved. I believe this will continue to be the case at LHC and as we use existing and proposed accelerators to turn theoretical conjecture into tangible reality. At some point this will no doubt evolve into a precision science, and that will make the field more respectable, but for my taste, the 'wild west' times are the most fun.

  20. High Energy Density Science at the Linac Coherent Light Source

    Energy Technology Data Exchange (ETDEWEB)

    Lee, R W

    2007-10-19

    High energy density science (HEDS), as a discipline that has developed in the United States from National Nuclear Security Agency (NNSA)-sponsored laboratory research programs, is, and will remain, a major component of the NNSA science and technology strategy. Its scientific borders are not restricted to NNSA. 'Frontiers in High Energy Density Physics: The X-Games of Contemporary Science' identified numerous exciting scientific opportunities in this field, while pointing to the need for a overarching interagency plan for its evolution. Meanwhile, construction of the first x-ray free-electron laser, the Office-of-Science-funded Linear Coherent Light Source-LCLS: the world's first free electron x-ray laser, with 100-fsec time resolution, tunable x-ray energies, a high rep rate, and a 10 order-of-magnitude increase in brightness over any other x-ray source--led to the realization that the scientific needs of NNSA and the broader scientific community could be well served by an LCLS HEDS endstation employing both short-pulse and high-energy optical lasers. Development of this concept has been well received in the community. NNSA requested a workshop on the applicability of LCLS to its needs. 'High Energy Density Science at the LCLS: NNSA Defense Programs Mission Need' was held in December 2006. The workshop provided strong support for the relevance of the endstation to NNSA strategic requirements. The range of science that was addressed covered a wide swath of the vast HEDS phase space. The unique possibilities provided by the LCLS in areas of intense interest to NNSA Defense Programs were discussed. The areas of focus included warm dense matter and equations of state, hot dense matter, and behavior of high-pressure materials under conditions of high strain-rate and extreme dynamic loading. Development of new and advanced diagnostic techniques was also addressed. This report lays out the relevant science, as brief summaries (Ch. II), expanded

  1. Diagnostics for ion beam driven high energy density physics experiments.

    Science.gov (United States)

    Bieniosek, F M; Henestroza, E; Lidia, S; Ni, P A

    2010-10-01

    Intense beams of heavy ions are capable of heating volumetric samples of matter to high energy density. Experiments are performed on the resulting warm dense matter (WDM) at the NDCX-I ion beam accelerator. The 0.3 MeV, 30 mA K(+) beam from NDCX-I heats foil targets by combined longitudinal and transverse neutralized drift compression of the ion beam. Both the compressed and uncompressed parts of the NDCX-I beam heat targets. The exotic state of matter (WDM) in these experiments requires specialized diagnostic techniques. We have developed a target chamber and fielded target diagnostics including a fast multichannel optical pyrometer, optical streak camera, laser Doppler-shift interferometer (Velocity Interferometer System for Any Reflector), beam transmission diagnostics, and high-speed gated cameras. We also present plans and opportunities for diagnostic development and a new target chamber for NDCX-II.

  2. Diagnostics for ion beam driven high energy density physics experimentsa)

    Science.gov (United States)

    Bieniosek, F. M.; Henestroza, E.; Lidia, S.; Ni, P. A.

    2010-10-01

    Intense beams of heavy ions are capable of heating volumetric samples of matter to high energy density. Experiments are performed on the resulting warm dense matter (WDM) at the NDCX-I ion beam accelerator. The 0.3 MeV, 30 mA K+ beam from NDCX-I heats foil targets by combined longitudinal and transverse neutralized drift compression of the ion beam. Both the compressed and uncompressed parts of the NDCX-I beam heat targets. The exotic state of matter (WDM) in these experiments requires specialized diagnostic techniques. We have developed a target chamber and fielded target diagnostics including a fast multichannel optical pyrometer, optical streak camera, laser Doppler-shift interferometer (Velocity Interferometer System for Any Reflector), beam transmission diagnostics, and high-speed gated cameras. We also present plans and opportunities for diagnostic development and a new target chamber for NDCX-II.

  3. Targeted Delivery of Small Interfering RNA Using Reconstituted High-Density Lipoprotein Nanoparticles

    Directory of Open Access Journals (Sweden)

    Mian M.K. Shahzad

    2011-04-01

    Full Text Available RNA interference holds tremendous potential as a therapeutic approach, especially in the treatment of malignant tumors. However, efficient and biocompatible delivery methods are needed for systemic delivery of small interfering RNA (siRNA. To maintain a high level of growth, tumor cells scavenge high-density lipoprotein (HDL particles by overexpressing its receptor: scavenger receptor type B1 (SR-B1. In this study, we exploited this cellular characteristic to achieve efficient siRNA delivery and established a novel formulation of siRNA by incorporating it into reconstituted HDL (rHDL nanoparticles. Here, we demonstrate that rHDL nanoparticles facilitate highly efficient systemic delivery of siRNA in vivo, mediated by the SR-B1. Moreover, in therapeutic proof-of-concept studies, these nanoparticles were effective in silencing the expression of two proteins that are key to cancer growth and metastasis (signal transducer and activator of transcription 3 and focal adhesion kinase in orthotopic mouse models of ovarian and colorectal cancer. These data indicate that an rHDL nanoparticle is a novel and highly efficient siRNA carrier, and therefore, this novel technology could serve as the foundation for new cancer therapeutic approaches.

  4. Exploring high-density baryonic matter: Maximum freeze-out density

    Energy Technology Data Exchange (ETDEWEB)

    Randrup, Joergen [Lawrence Berkeley National Laboratory, Nuclear Science Division, Berkeley, CA (United States); Cleymans, Jean [University of Cape Town, UCT-CERN Research Centre and Department of Physics, Rondebosch (South Africa)

    2016-08-15

    The hadronic freeze-out line is calculated in terms of the net baryon density and the energy density instead of the usual T and μ{sub B}. This analysis makes it apparent that the freeze-out density exhibits a maximum as the collision energy is varied. This maximum freeze-out density has μ{sub B} = 400 - 500 MeV, which is above the critical value, and it is reached for a fixed-target bombarding energy of 20-30 GeV/N well within the parameters of the proposed NICA collider facility. (orig.)

  5. Development of high energy density electrical double layer capacitors

    Science.gov (United States)

    Devarajan, Thamarai selvi

    Electrochemical Double Layer capacitors (EDLCs) have shown themselves as a viable energy storage alternative. EDLCs have high power density, faster charge/discharge, wide operating temperature and long cycle life compared to batteries since it stores charge by physical separation. Despites all their advantages, their low energy density stand as a bottleneck for capacitors. This research aims to increase the energy density of EDLC without compromising the power density. Energy is proportional to the square of cell voltage. Cell voltage is mainly dependent on electrolyte breakdown. Electrolytes also provide ions for charge separation and conduction. Therefore various electrolytes (Solutes and Solvents) which can give high concentration, solubility and decomposition potential were characterized in the first part of the research. In that study, a novel ionic liquid OPBF4 had higher capacitance and comparable voltage window compared to commercial TEABF4 in Acetonitrile. However, the increased polarity of the fixed ring O-atom and the ion-ion interaction in OPBF4 was responsible for lowering its conductivity. Oxygenated ionic compounds with alkyl groups had lower stability due to beta elimination between two electron withdrawing atoms. Volume based thermodynamics and quantum chemical calculations were used to calculate ion size, HOMO/LUMO energies, and free energy changes and establish relationship with capacitance, redox potential and melting points respectively. In addition free energy of fusion was used to predict the melting point. Ion size had correlation with capacitance due to compact double layer formation. Free energy changes did not explain the differences in melting point and predicted dielectric constant was inconsistent with the polarity. This is presumably due to using Van der Waals volume instead of crystal structure volume and insufficient incorporation of polarization term. The HOMO/LUMO energies gave direct relation between oxidation and reduction

  6. Perpendicular patterned media for high density magnetic storage

    Science.gov (United States)

    Wong, Joyce Y.

    2000-11-01

    Current longitudinal thin-film media in magnetic hard- disk drives are facing an oncoming limit caused by the superparamagnetic effect, in which the individual grains in the medium become so small that they are no longer stable against thermal fluctuation. This situation is undesirable as the stored information may be lost within an unexpectedly short time frame. There have been several proposed solutions in addressing the superparamagnetic limit, and one of them is perpendicular patterned media. In this approach, a periodic array of magnetic pillars is defined lithographically on a non-magnetic substrate. Binary data of ``1'' or ``0'' can be stored in each of these elements, which have two possible magnetization directions perpendicular to the plane of the medium. In our perpendicular patterned media design, Ni columns of 150-230nm diameter with a 6:1 aspect ratio are embedded in an (AlGa)2O 3/GaAs substrate. The fabrication procedure uses a combination of high resolution electron beam lithography, dry etching, and electroplating. The high aspect ratio in the column is achieved by taking advantage of the high etching rate and selectivity of AlGaAs/GaAs over (AlGa)2O 3 in the Cl2 chemically assisted ion beam etching process. In addition to being a robust etching mask, the (AlGa)2O3 layer also plays an important role in the chemical mechanical polishing procedure to remove the overplated Ni mushrooms. Once the Ni columns are fabricated, magnetic characterization is performed using magnetic force microscopy and scanning magnetoresistance microscopy. The former measurement confirms that the electroplated Ni columns are magnetic while the latter determines whether the individual columns are stable enough to retain the recorded information. We have successfully demonstrated recording in our 170nm diameter Ni column array arranged in a square format using a commercial read/write head. This is the first demonstration of single magnetic column per bit data storage in a

  7. High Stocking Density Controls Phillyrea Angustifolia in Mediterranean Grasslands

    Science.gov (United States)

    Mesléard, François; Yavercovski, Nicole; Lefebvre, Gaétan; Willm, Loic; Bonis, Anne

    2017-03-01

    Extensive grazing applied in the form of low instantaneous pressure over a long period is a widespread management practice in protected areas. However this kind of stocking method does not always achieve the expected results, in particular because it fails to limit colonization by woody plants.This is the case in the relict xero-halophytic grasslands of the northern Mediterranean coastal region, subjected to widespread colonization by the shrub Phillyrea angustifolia despite the presence of extensive grazing. In this study, we investigated, for an equal annual stocking rate, the respective impact of high stocking density applied over a short period (mob grazing) and low stocking density applied over a long period on both P. angustifolia and herbaceous cover, using an in situ experimental design run for 7 years. Only mob grazing was effective both in controlling the establishment and increasing the mortality of P. angustifolia individuals. We did not find any difference after the 7 years of experimentation between the two stocking methods with regard to the herbaceous community parameters tested: species richness, diversity, evenness, contribution of annual characteristic species. By contrast, the exclusion of domestic grazing led to a strong reduction of these values.The use of mob grazing may be well suited for meeting conservation goals such as maintaining open habitats in these grasslands.

  8. High density collinear holographic data storage system (Conference Presentation)

    Science.gov (United States)

    Tan, Xiaodi; Horimai, Hideyoshi; Arai, Ryo; Ikeda, Junichi; Inoue, Mitsuteru; Lin, Xiao; Xu, Ke; Liu, Jinpeng; Huang, Yong

    2016-09-01

    Collinear holography has been good candidate for a volumetric recording technology of holographic data storage system (HDSS), because of there are not only large storage capacities, high transfer rates, but also the unique configuration, in which the information and reference beams are modulated co-axially by the same spatial light modulator, as a new read/write method for HDSS are very promising. The optical pickup can be designed as small as DVDs, and can be placed on one side of the recording media (disc). In the disc structure, the preformatted reflective layer is used for the focus/tracking servo and reading address information, and a dichroic mirror layer is used for detecting holographic recording information without interfering with the preformatted information. A 2-dimensional digital page data format is used and the shift-multiplexing method is employed to increase recording density. As servo technologies are being introduced to control the objective lens to be maintained precisely to the disc in the recording and reconstructing process, a vibration isolator is no longer necessary. In this paper, we introduced the principle of the collinear holography and its media structure of disc. Some results of experimental and theoretical studies suggest that it is a very effective method. We also discussed some methods to increase the recording density and data transfer rates of collinear holography using phase modulated page data format.

  9. High Current Density 2D/3D Esaki Tunnel Diodes

    CERN Document Server

    Krishnamoorthy, Sriram; Lee, Choong Hee; Zhang, Yuewei; McCulloch, William D; Johnson, Jared M; Hwang, Jinwoo; Wu, Yiying; Rajan, Siddharth

    2016-01-01

    The integration of two-dimensional materials such as transition metal dichalcogenides with bulk semiconductors offer interesting opportunities for 2D/3D heterojunction-based novel device structures without any constraints of lattice matching. By exploiting the favorable band alignment at the GaN/MoS2 heterojunction, an Esaki interband tunnel diode is demonstrated by transferring large area, Nb-doped, p-type MoS2 onto heavily n-doped GaN. A peak current density of 446 A/cm2 with repeatable room temperature negative differential resistance, peak to valley current ratio of 1.2, and minimal hysteresis was measured in the MoS2/GaN non-epitaxial tunnel diode. A high current density of 1 kA/cm2 was measured in the Zener mode (reverse bias) at -1 V bias. The GaN/MoS2 tunnel junction was also modeled by treating MoS2 as a bulk semiconductor, and the electrostatics at the 2D/3D interface was found to be crucial in explaining the experimentally observed device characteristics.

  10. Formation of FRCs on the Pulsed High Density Experiment

    Science.gov (United States)

    Andreason, Samuel; Slough, John

    2008-11-01

    The Pulsed High Density (PHD) experiment has been reassembled at a new facility with sufficient space to continue through the full acceleration and compression stages to reach breakeven. The intention here is to produce a large FRC, but remain in the kinetic regime where the FRC is stable and the transport sufficiently low that a Q > 1 plasma can be attained at moderate densities ˜ 10^23 m-3. During reassembly a more complete analysis of previous experimental results has been made. One of the issues in the early phase of the experiment was inefficient flux trapping during field reversal due to the large scale of the FRC source (0.4 m radius). The on-axis seed plasma was unable to diffuse out to the walls on a timescale commensurate with the introduction of bias fields. This resulted in more than half of the initial bias flux lost before sheath formation halted flux loss. An annular array of plasma sources has been constructed that solves this problem and greatly enhances the flux retention. Dynamic formation has been employed on PHD and analysis tools capable of interpreting the magnetic loop diagnostic array have been developed. Results with comparison to numerical models will be presented.

  11. OLEOPHOBIC AND HYDROPHOBIC FEATURE EXPERIMENTS OF FLUORINATED HIGH DENSITY POLYETHYLENE

    Institute of Scientific and Technical Information of China (English)

    杨宏伟; 魏贤勇; 费逸伟; 孙世安; 李晓越

    2013-01-01

    The surface performances of directly fluorinated high density polyethylene (HDPE) are studied with Fourier transform infrared (FT-IR) spectra ,scanning electron microscopy (SEM) and contact angle (CA) system . The SEM images show that there is a three-layer structure called the reaction ,virgin and boundary layer structure . The depth of fluorinated layer is 5.75 μm with 1 h fluorination time and 7.86 μm with 2 h . The depths are 5.46 μm and 5.07 μm when fluorine density is 2% and 1% ,respectively .CA indicates that the HDPE surface property becomes more hydrophobic with the increasing water contact angle from 78.5° to 104.5° .Oleophobic and hydrophobic features of HDPE are identified by comparison of mass change experiments .It is shown that the in-crement rate of fluorinated HDPE is much lower than that of un-fluorinated HDPE filled in neither distilled water nor jet fuel .

  12. Carrier lifetimes in thin-film photovoltaics

    Science.gov (United States)

    Baek, Dohyun

    2015-09-01

    The carrier lifetimes in thin-film solar cells are reviewed and discussed. Shockley-Read-Hall recombination is dominant at low carrier density, Auger recombination is dominant under a high injection condition and high carrier density, and surface recombination is dominant under any conditions. Because the surface photovoltage technique is insensitive to the surface condition, it is useful for bulk lifetime measurements. The photoconductance decay technique measures the effective recombination lifetime. The time-resolved photoluminescence technique is very useful for measuring thin-film semiconductor or solar-cell materials lifetime, because the sample is thin, other techniques are not suitable for measuring the lifetime. Many papers have provided time-resolved photoluminescence (TRPL) lifetimes for copper-indium-gallium-selenide (CIGS) and CdTe thin-film solar cell. The TRPL lifetime strongly depends on open-circuit voltage and conversion efficiency; however, the TRPL life time is insensitive to the short-circuit current.

  13. High intrinsic carrier mobility and photon absorption in the perovskite CH3NH3PbI3.

    Science.gov (United States)

    Wang, Youwei; Zhang, Yubo; Zhang, Peihong; Zhang, Wenqing

    2015-05-07

    The carrier transport and optical properties of the hybrid organic-inorganic perovskite CH3NH3PbI3 are investigated using first-principles approaches. We found that the electron and hole mobilities could reach surprisingly high values of 7-30 × 10(3) and 1.5-5.5 × 10(3) cm(2) V(-1) s(-1), respectively, and both are estimated to be much higher than the current experimental measurements. The high carrier mobility is ascribed to the intrinsically small effective masses of anti-bonding band-edge states. The above results imply that there is still space to improve the performance of related solar cells. This material also has a sharp photon absorption edge and an absorption coefficient as high as 10(5) cm(-1), both of which contribute to effective utilization of solar radiation. Although band-edge states are mainly derived from the inorganic ions of Pb and I, thermal movement of the organic base has indirect influences on the bandgap and carrier effective masses, resulting in the temperature-dependent solar cell efficiencies.

  14. High short-circuit current density CdTe solar cells using all-electrodeposited semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Echendu, O.K., E-mail: oechendu@yahoo.com; Fauzi, F.; Weerasinghe, A.R.; Dharmadasa, I.M.

    2014-04-01

    CdS/CdTe and ZnS/CdTe n–n heterojunction solar cells have been fabricated using all-electrodeposited semiconductors. The best devices show remarkable high short-circuit current densities of 38.5 mAcm{sup −2} and 47.8 mAcm{sup −2}, open-circuit voltages of 630 mV and 646 mV and conversion efficiencies of 8.0% and 12.0% respectively. The major strength of these device structures lies in the combination of n–n heterojunction with a large Schottky barrier at the n-CdTe/metal back contact which provides the required band bending for the separation of photo-generated charge carriers. This is in addition to the use of a high quality n-type CdTe absorber layer with high electron mobility. The potential barrier heights estimated for these devices from the current–voltage characteristics exceed 1.09 eV and 1.13 eV for CdS/CdTe and ZnS/CdTe cells respectively. The diode rectification factors of both devices are in excess of four orders of magnitude with reverse saturation current densities of 1.0 × 10{sup −7} Acm{sup −2} and 4.0 × 10{sup −7} Acm{sup −2} respectively. These all-electrodeposited solar cell device structures are currently being studied and developed as an alternative to the well-known p–n junction structures which utilise chemical bath-deposited CdS. The preliminary material growth, device fabrication and assessment results are presented in this paper. - Highlights: • Two-electrode deposition. • High J{sub sc} Schottky barrier solar cells. • CdCl{sub 2} + CdF{sub 2} treatment.

  15. Electronic characteristics of p-type transparent SnO monolayer with high carrier mobility

    Science.gov (United States)

    Du, Juan; Xia, Congxin; Liu, Yaming; Li, Xueping; Peng, Yuting; Wei, Shuyi

    2017-04-01

    More recently, two-dimensional (2D) SnO nanosheets are attaching great attention due to its excellent carrier mobility and transparent characteristics. Here, the stability, electronic structures and carrier mobility of SnO monolayer are investigated by using first-principles calculations. The calculations of the phonon dispersion spectra indicate that SnO monolayer is dynamically stable. Moreover, the band gap values are decreased from 3.93 eV to 2.75 eV when the tensile strain is applied from 0% to 12%. Interestingly, SnO monolayer is a p-type transparent semiconducting oxide with hole mobility of 641 cm2 V-1 s-1, which is much higher than that of MoS2 monolayer. These findings make SnO monolayer becomes a promising 2D material for applications in nanoelectronic devices.

  16. Device Architecture and Materials for Organic Light-Emitting Devices Targeting High Current Densities and Control of the Triplet Concentration

    CERN Document Server

    Schols, Sarah

    2011-01-01

    Device Architecture and Materials for Organic Light-Emitting Devices focuses on the design of new device and material concepts for organic light-emitting devices, thereby targeting high current densities and an improved control of the triplet concentration. A new light-emitting device architecture, the OLED with field-effect electron transport, is demonstrated. This device is a hybrid between a diode and a field-effect transistor. Compared to conventional OLEDs, the metallic cathode is displaced by one to several micrometers from the light-emitting zone, reducing optical absorption losses. The electrons injected by the cathode accumulate at an organic heterojunction and are transported to the light-emission zone by field-effect. High mobilities for charge carriers are achieved in this way, enabling a high current density and a reduced number of charge carriers in the device. Pulsed excitation experiments show that pulses down to 1 µs can be applied to this structure without affecting the light intensity, sug...

  17. Highly immunogenic and fully synthetic peptide-carrier constructs targetting GnRH

    DEFF Research Database (Denmark)

    Beekman, N.J.C.M.; Schaaper, W.M.M.; Turkstra, J.A.;

    1999-01-01

    using a tandem GnRH peptide as a branched polylysine construct, a lipo-thioester, a lipo-amide or a KLH conjugate in CFA, and the lipoamide peptide in an immuno-stimulating complex (ISCOM). We found the lipo-thioester and the branched polylysine constructs to be the most effective carrier molecules...... for the induction of antibodies against GnRH and immunocastration of pigs....

  18. Strongly interacting matter at high densities with a soliton model

    Science.gov (United States)

    Johnson, Charles Webster

    1998-12-01

    One of the major goals of modern nuclear physics is to explore the phase diagram of strongly interacting matter. The study of these 'extreme' conditions is the primary motivation for the construction of the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory which will accelerate nuclei to a center of mass (c.m.) energy of about 200 GeV/nucleon. From a theoretical perspective, a test of quantum chromodynamics (QCD) requires the expansion of the conditions examined from one phase point to the entire phase diagram of strongly-interacting matter. In the present work we focus attention on what happens when the density is increased, at low excitation energies. Experimental results from the Brookhaven Alternating Gradient Synchrotron (AGS) indicate that this regime may be tested in the 'full stopping' (maximum energy deposition) scenario achieved at the AGS having a c.m. collision energy of about 2.5 GeV/nucleon for two equal- mass heavy nuclei. Since the solution of QCD on nuclear length-scales is computationally prohibitive even on today's most powerful computers, progress in the theoretical description of high densities has come through the application of models incorporating some of the essential features of the full theory. The simplest such model is the MIT bag model. We use a significantly more sophisticated model, a nonlocal confining soliton model developed in part at Kent. This model has proven its value in the calculation of the properties of individual mesons and nucleons. In the present application, the many-soliton problem is addressed with the same model. We describe nuclear matter as a lattice of solitons and apply the Wigner-Seitz approximation to the lattice. This means that we consider spherical cells with one soliton centered in each, corresponding to the average properties of the lattice. The average density is then varied by changing the size of the Wigner-Seitz cell. To arrive at a solution, we need to solve a coupled set of

  19. A ferroelectric DRAM cell for high-density NVRAM's

    Science.gov (United States)

    Moazzami, Reza; Hu, Chenming; Shepherd, William H.

    1990-10-01

    The operation of a ferroelectric DRAM (dynamic random-access memory) cell for nonvolatile RAM (NVRAM) applications is described. Because polarization reversal only occurs during nonvolatile store/recall operations and not during read/write operations, ferroelectric fatigue is not a serious endurance problem. For a 3-V power supply, the worst-case effective silicon dioxide thickness of the unoptimized lead zirconate titanate film studied is less than 1.7 nm. The resistivity and endurance properties of ferroelectric films can be optimized by modifying the composition of the film. This cell can be the basis of a very-high-density NVRAM with practically no read/write cycle limit and at least 10 to the 10th nonvolatile store/recall cycles.

  20. [Cholesterol in serum high density lipoprotein fraction (author's transl)].

    Science.gov (United States)

    Schatz, C; Jeanblanc, B; Offner, M

    1980-11-22

    The risk of atheroma can be assessed and valid epidemiological surveys can be carried out by measuring cholesterol in serum high density lipoprotein fraction (HDL) and calculating the HDL cholesterol: VLDL + LDL ratio. This was done in 39 patients free from surgically confirmed atheromatous lesions and in 51 patients presenting with such lesions. Of the four different techniques used for separation in these patients (ultracentrifugation, precipitation with heparin-Mn2+, precipitation with phosphotungstate-Mg2+ and electrophoresis), precipitation with phosphotungstate-Mg/2+ seems to be the most suitable, since there is no degradation of the HDL fraction as during electrophoresis on polyacrylamide gel, and less floculation of the supernatant after separation. Contrary to ultracentrifugation, which requires sophisticated equipment and good technical skill, the technique is easily carried out.

  1. High-density polyethylene dosimetry by transvinylene FTIR analysis

    DEFF Research Database (Denmark)

    McLaughlin, W.L.; Silverman, J.; Al-Sheikhly, M.

    1999-01-01

    . The transvinylene response in air to gamma radiation is linear with dose and has relatively low yield compared with the response to electrons, whereas the response in deaerated polyethylene samples is also linear, but is more sensitive, and has negligible dose-rate dependence in its response to gamma rays...... and electrons. The useful dose range of 0.053 cm thick high-density polyethylene film (rho = 0.961 g cm(-3); melt index = 0.8 dg min(-1)), for irradiations by (60)Co gamma radiation and 2.0 and 0.4 MeV electron beams in deaerated atmosphere (Na gas), is about 50-10(3) kGy for FTIR transvinylene...

  2. 5th International conference on High Energy Density Laboratory Astrophysics

    CERN Document Server

    Kyrala, G.A

    2005-01-01

    During the past several years, research teams around the world have developed astrophysics-relevant utilizing high energy-density facilities such as intense lasers and z-pinches. Research is underway in many areas, such as compressible hydrodynamic mixing, strong shock phenomena, radiation flow, radiative shocks and jets, complex opacities, equations o fstat, and relativistic plasmas. Beyond this current research and the papers it is producing, plans are being made for the application, to astrophysics-relevant research, of the 2 MJ National Ignition Facility (NIF) laser at Lawrence Livermore National Laboratory; the 600 kj Ligne d'Intergration Laser (LIL) and the 2 MJ Laser Megajoule (LMJ) in Bordeaux, France; petawatt-range lasers now under construction around the world; and current and future Z pinches. The goal of this conference and these proceedings is to continue focusing and attention on this emerging research area. The conference brought together different scientists interested in this emerging new fi...

  3. Scoping study. High density polyethylene (HDPE) in salstone service

    Energy Technology Data Exchange (ETDEWEB)

    Phifer, Mark A. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2005-02-18

    An evaluation of the use of high density polyethylene (HDPE) geomembranes in Saltstone service has been conducted due to the potential benefits that could be derived from such usage. HDPE is one of the simplest hydrocarbon polymers and one of the most common polymers utilized in the production of geomembranes, which means that its costs are relatively low. Additionally, HDPE geomembranes have an extremely low permeability and an extremely low water vapor diffusional flux, which means that it is a good barrier to contaminant transport. The primary consideration in association with HDPE geomembranes in Saltstone service is the potential impact of Saltstone on the degradation of the HDPE geomembranes. Therefore, the evaluation documented herein has primarily focused upon the potential HDPE degradation in Saltstone service.

  4. The alterations in high density polyethylene properties with gamma irradiation

    Science.gov (United States)

    Zaki, M. F.; Elshaer, Y. H.; Taha, Doaa. H.

    2017-10-01

    In the present investigation, high density polyethylene (HDPE) polymer has been used to study the alterations in its properties under gamma-irradiation. Physico-chemical properties have been investigated with different spectroscopy techniques, Fourier Transform Infrared spectroscopy (FTIR), X-ray diffraction (XRD), biocompatibility properties, as well as, mechanical properties change. The FT-IR analysis shows the formation of new band at 1716 cm-1 that is attributed to the oxidation of irradiated polymer chains, which is due to the formation of carbonyl groups (C˭O). XRD patterns show that a decrease in the crystallite size and increase in the Full Width at Half Maximum (FWHM). This means that the crystallinity of irradiated samples is decreased with increase in gamma dose. The contact angle measurements show an increase in the surface free energy as the gamma irradiation increases. The measurements of mechanical properties of irradiated HDPE samples were discussed.

  5. Ultracold molecular Rydberg physics in a high density environment

    CERN Document Server

    Eiles, Matthew T; Robicheaux, F; Greene, Chris H

    2016-01-01

    Sufficiently high densities in Bose-Einstein condensates provide favorable conditions for the production of ultralong-range polyatomic molecules consisting of one Rydberg atom and a number of neutral ground state atoms. The chemical binding properties and electronic wave functions of these exotic molecules are investigated analytically via hybridized diatomic states. The effects of the molecular geometry on the system's properties are studied through comparisons of the adiabatic potential curves and electronic structures for both symmetric and randomly configured molecular geometries. General properties of these molecules with increasing numbers of constituent atoms and in different geometries are presented. These polyatomic states have spectral signatures that lead to non-Lorentzian line-profiles.

  6. Single-Readout High-Density Memristor Crossbar

    KAUST Repository

    Zidan, M. A.

    2016-01-07

    High-density memristor-crossbar architecture is a very promising technology for future computing systems. The simplicity of the gateless-crossbar structure is both its principal advantage and the source of undesired sneak-paths of current. This parasitic current could consume an enormous amount of energy and ruin the readout process. We introduce new adaptive-threshold readout techniques that utilize the locality and hierarchy properties of the computer-memory system to address the sneak-paths problem. The proposed methods require a single memory access per pixel for an array readout. Besides, the memristive crossbar consumes an order of magnitude less power than state-of-the-art readout techniques.

  7. Characterization of high density through silicon vias with spectral reflectometry.

    Science.gov (United States)

    Ku, Yi-Sha; Huang, Kuo Cheng; Hsu, Weite

    2011-03-28

    Measurement and control is an important step for production-worthy through silicon vias etch. We demonstrate the use and enhancement of an existing wafer metrology tool, spectral reflectometer by implementing novel theoretical model and measurement algorithm for high density through-silicon via (HDTSV) inspection. It is capable of measuring depth and depth variations of array vias by Discrete Fourier Transform (DFT) analysis in one shot measurement. Surface roughness of via bottom can also be extracted by scattering model fitting. Our non-destructive solution can measure TSV profile diameters as small as 5 μm and aspect ratios greater than 13:1. The measurement precision is in the range of 0.02 μm. Metrology results from actual 3D interconnect processing wafers are presented.

  8. Ultra-high current density thin-film Si diode

    Science.gov (United States)

    Wang, Qi

    2008-04-22

    A combination of a thin-film .mu.c-Si and a-Si:H containing diode structure characterized by an ultra-high current density that exceeds 1000 A/cm.sup.2, comprising: a substrate; a bottom metal layer disposed on the substrate; an n-layer of .mu.c-Si deposited the bottom metal layer; an i-layer of .mu.c-Si deposited on the n-layer; a buffer layer of a-Si:H deposited on the i-layer, a p-layer of .mu.c-Si deposited on the buffer layer; and a top metal layer deposited on the p-layer.

  9. Sulfurized activated carbon for high energy density supercapacitors

    Science.gov (United States)

    Huang, Yunxia; Candelaria, Stephanie L.; Li, Yanwei; Li, Zhimin; Tian, Jianjun; Zhang, Lili; Cao, Guozhong

    2014-04-01

    Sulfurized activated carbon (SAC), made by coating the pore surface with thiophenic sulfur functional groups from the pyrolysis of sulfur flakes, were characterized and tested for supercapacitor applications. From X-ray photoelectron spectroscopy (XPS), the sulfur content in the SAC was found to be 2.7 at%. Electrochemical properties from potentiostatic and galvanostatic measurements, and electrochemical impedance spectroscopy (EIS) were used to evaluate the effect of sulfur on porous carbon electrodes. The SAC electrode exhibits better conductivity, and an obvious increase in specific capacitance that is almost 40% higher than plain activated carbons (ACs) electrode at a high current density of 1.4 A g-1. The proposed mechanism for improved conductivity and capacitive performance due to the sulfur functional groups on ACs will be discussed.

  10. High-density avalanche chambers for positron emission tomography

    Energy Technology Data Exchange (ETDEWEB)

    Manfrass, P.; Enghardt, W.; Fromm, W.D.; Wohlfarth, D.; Hohmuth, K.

    1988-12-15

    A positron tomograph for radiopharmaceutical and medical research is under construction. In its final stage it will cover six high-density avalanche chambers (HIDAC) in a hexagonal arrangement. Each detector with a sensitive area of 50x28 cm/sup 2/ will consist of a stack of four pairs of multihole photon-to-electron converters with a multiwire proportional counter (MWPC) in between. An experimental investigation of detector properties as time and spatial resolutions as well as detector efficiency in dependence to converter structure, electric field strength and counting gas mixture preceded the final design of these detectors. Results of these studies are outlined. Furthermore, longitudinal tomograms taken with a stationary test camera are presented.

  11. High-density percutaneous chronic connector for neural prosthetics

    Science.gov (United States)

    Shah, Kedar G.; Bennett, William J.; Pannu, Satinderpall S.

    2015-09-22

    A high density percutaneous chronic connector, having first and second connector structures each having an array of magnets surrounding a mounting cavity. A first electrical feedthrough array is seated in the mounting cavity of the first connector structure and a second electrical feedthrough array is seated in the mounting cavity of the second connector structure, with a feedthrough interconnect matrix positioned between a top side of the first electrical feedthrough array and a bottom side of the second electrical feedthrough array to electrically connect the first electrical feedthrough array to the second electrical feedthrough array. The two arrays of magnets are arranged to attract in a first angular position which connects the first and second connector structures together and electrically connects the percutaneously connected device to the external electronics, and to repel in a second angular position to facilitate removal of the second connector structure from the first connector structure.

  12. CENTER FOR PULSED POWER DRIVEN HIGH ENERGY DENSITY PLASMA STUDIES

    Energy Technology Data Exchange (ETDEWEB)

    Professor Bruce R. Kusse; Professor David A. Hammer

    2007-04-18

    This annual report summarizes the activities of the Cornell Center for Pulsed-Power-Driven High-Energy-Density Plasma Studies, for the 12-month period October 1, 2005-September 30, 2006. This period corresponds to the first year of the two-year extension (awarded in October, 2005) to the original 3-year NNSA/DOE Cooperative Agreement with Cornell, DE-FC03-02NA00057. As such, the period covered in this report also corresponds to the fourth year of the (now) 5-year term of the Cooperative Agreement. The participants, in addition to Cornell University, include Imperial College, London (IC), the University of Nevada, Reno (UNR), the University of Rochester (UR), the Weizmann Institute of Science (WSI), and the P.N. Lebedev Physical Institute (LPI), Moscow. A listing of all faculty, technical staff and students, both graduate and undergraduate, who participated in Center research activities during the year in question is given in Appendix A.

  13. Methods and systems for rapid prototyping of high density circuits

    Science.gov (United States)

    Palmer, Jeremy A.; Davis, Donald W.; Chavez, Bart D.; Gallegos, Phillip L.; Wicker, Ryan B.; Medina, Francisco R.

    2008-09-02

    A preferred embodiment provides, for example, a system and method of integrating fluid media dispensing technology such as direct-write (DW) technologies with rapid prototyping (RP) technologies such as stereolithography (SL) to provide increased micro-fabrication and micro-stereolithography. A preferred embodiment of the present invention also provides, for example, a system and method for Rapid Prototyping High Density Circuit (RPHDC) manufacturing of solderless connectors and pilot devices with terminal geometries that are compatible with DW mechanisms and reduce contact resistance where the electrical system is encapsulated within structural members and manual electrical connections are eliminated in favor of automated DW traces. A preferred embodiment further provides, for example, a method of rapid prototyping comprising: fabricating a part layer using stereolithography and depositing thermally curable media onto the part layer using a fluid dispensing apparatus.

  14. Thermolysis of High-Density Polyethylene to Petroleum Products

    Directory of Open Access Journals (Sweden)

    Sachin Kumar

    2013-01-01

    Full Text Available Thermal degradation of plastic polymers is becoming an increasingly important method for the conversion of plastic materials into valuable chemicals and oil products. In this work, virgin high-density polyethylene (HDPE was chosen as a material for pyrolysis. A simple pyrolysis reactor system has been used to pyrolyse virgin HDPE with an objective to optimize the liquid product yield at a temperature range of 400°C to 550°C. The chemical analysis of the HDPE pyrolytic oil showed the presence of functional groups such as alkanes, alkenes, alcohols, ethers, carboxylic acids, esters, and phenyl ring substitution bands. The composition of the pyrolytic oil was analyzed using GC-MS, and it was found that the main constituents were n-Octadecane, n-Heptadecane, 1-Pentadecene, Octadecane, Pentadecane, and 1-Nonadecene. The physical properties of the obtained pyrolytic oil were close to those of mixture of petroleum products.

  15. Flexible asymmetric supercapacitors with high energy and high power density in aqueous electrolytes.

    Science.gov (United States)

    Cheng, Yingwen; Zhang, Hongbo; Lu, Songtao; Varanasi, Chakrapani V; Liu, Jie

    2013-02-07

    Supercapacitors with both high energy and high power densities are critical for many practical applications. In this paper, we discuss the design and demonstrate the fabrication of flexible asymmetric supercapacitors based on nanocomposite electrodes of MnO(2), activated carbon, carbon nanotubes and graphene. The combined unique properties of each of these components enable highly flexible and mechanically strong films that can serve as electrodes directly without using any current collectors or binders. Using these flexible electrodes and a roll-up approach, asymmetric supercapacitors with 2 V working voltage were successfully fabricated. The fabricated device showed excellent rate capability, with 78% of the original capacitance retained when the scan rate was increased from 2 mV s(-1) to 500 mV s(-1). Owing to the unique composite structure, these supercapacitors were able to deliver high energy density (24 W h kg(-1)) under high power density (7.8 kW kg(-1)) conditions. These features could enable supercapacitor based energy storage systems to be very attractive for a variety of critical applications, such as the power sources in hybrid electric vehicles and the back-up powers for wind and solar energy, where both high energy density and high power density are required.

  16. Extended MHD Effects in High Energy Density Experiments

    Science.gov (United States)

    Seyler, Charles

    2016-10-01

    The MHD model is the workhorse for computational modeling of HEDP experiments. Plasma models are inheritably limited in scope, but MHD is expected to be a very good model for studying plasmas at the high densities attained in HEDP experiments. There are, however, important ways in which MHD fails to adequately describe the results, most notably due to the omission of the Hall term in the Ohm's law (a form of extended MHD or XMHD). This talk will discuss these failings by directly comparing simulations of MHD and XMHD for particularly relevant cases. The methodology is to simulate HEDP experiments using a Hall-MHD (HMHD) code based on a highly accurate and robust Discontinuous Galerkin method, and by comparison of HMHD to MHD draw conclusions about the impact of the Hall term. We focus on simulating two experimental pulsed power machines under various scenarios. We examine the MagLIF experiment on the Z-machine at Sandia National Laboratories and liner experiments on the COBRA machine at Cornell. For the MagLIF experiment we find that power flow in the feed leads to low density plasma ablation into the region surrounding the liner. The inflow of this plasma compresses axial magnetic flux onto the liner. In MHD this axial flux tends to resistively decay, whereas in HMHD a force-free current layer sustains the axial flux on the liner leading to a larger ratio of axial to azimuthal flux. During the liner compression the magneto-Rayleigh-Taylor instability leads to helical perturbations due to minimization of field line bending. Simulations of a cylindrical liner using the COBRA machine parameters can under certain conditions exhibit amplification of an axial field due to a force-free low-density current layer separated by some distance from the liner. This results in a configuration in which there is predominately axial field on the liner inside the current layer and azimuthal field outside the layer. We are currently attempting to experimentally verify the simulation

  17. Modulation of low-density lipoprotein-induced inhibition of intercellular communication by antioxidants and high-density lipoproteins

    NARCIS (Netherlands)

    Zwijsen, R M; de Haan, L. H. J.; Kuivenhoven, J A; Nusselder, I C

    1991-01-01

    In order to study the capacity of antioxidants and high-density lipoproteins (HDL) to modulate the effects of low-density lipoprotein (LDL) on intercellular communication, arterial smooth muscle cells and a dye transfer method were used. LDL, in contrast to HDL, inhibited the communication between a

  18. Modulation of low-density lipoprotein-induced inhibition of intercellular communication by antioxidants and high-density lipoproteins

    NARCIS (Netherlands)

    Zwijsen, R M; de Haan, L. H. J.; Kuivenhoven, J A; Nusselder, I C

    In order to study the capacity of antioxidants and high-density lipoproteins (HDL) to modulate the effects of low-density lipoprotein (LDL) on intercellular communication, arterial smooth muscle cells and a dye transfer method were used. LDL, in contrast to HDL, inhibited the communication between

  19. Low-temperature carrier dynamics in high-mobility organic transistors of alkylated dinaphtho-thienothiophene as investigated by electron spin resonance

    Energy Technology Data Exchange (ETDEWEB)

    Kinoshita, Yutaro; Tanaka, Hisaaki, E-mail: htanaka@nuap.nagoya-u.ac.jp; Kuroda, Shin-ichi [Department of Applied Physics, Nagoya University, Chikusa, Nagoya 464-8603 (Japan); Shimoi, Yukihiro [Nanosystem Research Institute (NRI), National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568 (Japan); Takimiya, Kazuo [Emergent Molecular Function Research Group, RIKEN Center for Emergent Matter Science (CEMS), Wako, Saitama 351-0198 (Japan)

    2014-07-21

    Charge carriers in high-mobility organic thin-film transistors of alkylated dinaphtho-thienothiophene (C{sub 10}-DNTT) have been directly observed by field-induced electron spin resonance (FI-ESR) down to 4 K. FI-ESR spectra of π-electron hole carriers of C{sub 10}-DNTT exhibited clear anisotropy, indicating a highly organized end-on molecular orientation at the device interface. The intra-grain and inter-grain carrier motion were probed by the motional narrowing effect of the ESR spectra. The intra-grain motion was clearly observed even at 4 K, showing intrinsically high mobility of C{sub 10}-DNTT crystallites. On the other hand, significantly low activation energy of ∼10 meV for inter-grain carrier hopping, compared with pristine DNTT, was observed, which shows that the alkyl substitution drastically enhances the carrier mobility of DNTT system.

  20. Numerical methods for high-dimensional probability density function equations

    Science.gov (United States)

    Cho, H.; Venturi, D.; Karniadakis, G. E.

    2016-01-01

    In this paper we address the problem of computing the numerical solution to kinetic partial differential equations involving many phase variables. These types of equations arise naturally in many different areas of mathematical physics, e.g., in particle systems (Liouville and Boltzmann equations), stochastic dynamical systems (Fokker-Planck and Dostupov-Pugachev equations), random wave theory (Malakhov-Saichev equations) and coarse-grained stochastic systems (Mori-Zwanzig equations). We propose three different classes of new algorithms addressing high-dimensionality: The first one is based on separated series expansions resulting in a sequence of low-dimensional problems that can be solved recursively and in parallel by using alternating direction methods. The second class of algorithms relies on truncation of interaction in low-orders that resembles the Bogoliubov-Born-Green-Kirkwood-Yvon (BBGKY) framework of kinetic gas theory and it yields a hierarchy of coupled probability density function equations. The third class of algorithms is based on high-dimensional model representations, e.g., the ANOVA method and probabilistic collocation methods. A common feature of all these approaches is that they are reducible to the problem of computing the solution to high-dimensional equations via a sequence of low-dimensional problems. The effectiveness of the new algorithms is demonstrated in numerical examples involving nonlinear stochastic dynamical systems and partial differential equations, with up to 120 variables.

  1. Numerical methods for high-dimensional probability density function equations

    Energy Technology Data Exchange (ETDEWEB)

    Cho, H. [Department of Mathematics, University of Maryland College Park, College Park, MD 20742 (United States); Venturi, D. [Department of Applied Mathematics and Statistics, University of California Santa Cruz, Santa Cruz, CA 95064 (United States); Karniadakis, G.E., E-mail: gk@dam.brown.edu [Division of Applied Mathematics, Brown University, Providence, RI 02912 (United States)

    2016-01-15

    In this paper we address the problem of computing the numerical solution to kinetic partial differential equations involving many phase variables. These types of equations arise naturally in many different areas of mathematical physics, e.g., in particle systems (Liouville and Boltzmann equations), stochastic dynamical systems (Fokker–Planck and Dostupov–Pugachev equations), random wave theory (Malakhov–Saichev equations) and coarse-grained stochastic systems (Mori–Zwanzig equations). We propose three different classes of new algorithms addressing high-dimensionality: The first one is based on separated series expansions resulting in a sequence of low-dimensional problems that can be solved recursively and in parallel by using alternating direction methods. The second class of algorithms relies on truncation of interaction in low-orders that resembles the Bogoliubov–Born–Green–Kirkwood–Yvon (BBGKY) framework of kinetic gas theory and it yields a hierarchy of coupled probability density function equations. The third class of algorithms is based on high-dimensional model representations, e.g., the ANOVA method and probabilistic collocation methods. A common feature of all these approaches is that they are reducible to the problem of computing the solution to high-dimensional equations via a sequence of low-dimensional problems. The effectiveness of the new algorithms is demonstrated in numerical examples involving nonlinear stochastic dynamical systems and partial differential equations, with up to 120 variables.

  2. Probucol alleviates atherosclerosis and improves high density lipoprotein function

    Directory of Open Access Journals (Sweden)

    Zhong Jian-Kai

    2011-11-01

    Full Text Available Abstract Background Probucol is a unique hypolipidemic agent that decreases high density lipoprotein cholesterol (HDL-C. However, it is not definite that whether probucol hinders the progression of atherosclerosis by improving HDL function. Methods Eighteen New Zealand White rabbits were randomly divided into the control, atherosclerosis and probucol groups. Control group were fed a regular diet; the atherosclerosis group received a high fat diet, and the probucol group received the high fat diet plus probucol. Hepatocytes and peritoneal macrophages were isolated for [3H] labeled cholesterol efflux rates and expression of ABCA1 and SR-B1 at gene and protein levels; venous blood was collected for serum paraoxonase 1, myeloperoxidase activity and lipid analysis. Aorta were prepared for morphologic and immunohistochemical analysis after 12 weeks. Results Compared to the atherosclerosis group, the paraoxonase 1 activity, cholesterol efflux rates, expression of ABCA1 and SR-BI in hepatocytes and peritoneal macrophages, and the level of ABCA1 and SR-BI in aortic lesions were remarkably improved in the probucol group, But the serum HDL cholesterol concentration, myeloperoxidase activity, the IMT and the percentage plaque area of aorta were significantly decreased. Conclusion Probucol alleviated atherosclerosis by improving HDL function. The mechanisms include accelerating the process of reverse cholesterol transport, improving the anti-inflammatory and anti-oxidant functions.

  3. Acrolein impairs the cholesterol transport functions of high density lipoproteins.

    Science.gov (United States)

    Chadwick, Alexandra C; Holme, Rebecca L; Chen, Yiliang; Thomas, Michael J; Sorci-Thomas, Mary G; Silverstein, Roy L; Pritchard, Kirkwood A; Sahoo, Daisy

    2015-01-01

    High density lipoproteins (HDL) are considered athero-protective, primarily due to their role in reverse cholesterol transport, where they transport cholesterol from peripheral tissues to the liver for excretion. The current study was designed to determine the impact of HDL modification by acrolein, a highly reactive aldehyde found in high abundance in cigarette smoke, on the cholesterol transport functions of HDL. HDL was chemically-modified with acrolein and immunoblot and mass spectrometry analyses confirmed apolipoprotein crosslinking, as well as acrolein adducts on apolipoproteins A-I and A-II. The ability of acrolein-modified HDL (acro-HDL) to serve as an acceptor of free cholesterol (FC) from COS-7 cells transiently expressing SR-BI was significantly decreased. Further, in contrast to native HDL, acro-HDL promotes higher neutral lipid accumulation in murine macrophages as judged by Oil Red O staining. The ability of acro-HDL to mediate efficient selective uptake of HDL-cholesteryl esters (CE) into SR-BI-expressing cells was reduced compared to native HDL. Together, the findings from our studies suggest that acrolein modification of HDL produces a dysfunctional particle that may ultimately promote atherogenesis by impairing functions that are critical in the reverse cholesterol transport pathway.

  4. SELDI-TOF mass spectrometry of High-Density Lipoprotein

    Directory of Open Access Journals (Sweden)

    Rezaee Farhad

    2007-09-01

    Full Text Available Abstract Background High-Density Lipoprotein (HDL, one of the main plasma lipoproteins, serves as a docking station for proteins involved in inflammation, coagulation, and lipid metabolism. Methods To elucidate the protein composition of HDL, we employed SELDI-TOF mass spectrometry as a potential high-throughput proteomic candidate for protein profiling of HDL. HDL derived from normolipemic individuals was captured on PS20 protein-chips using covalently bound antibodies against apo A-I or A-II. Results After optimisation, on-chip capture of HDL particles directly from plasma or from pre-purified HDL resulted in comparable fingerprints confirming specific capture of HDL. Depending on the capture antibody some differences in the fingerprint were observed. The most detailed fingerprint was observed up to 50 kDa; approximately 95 peaks were detected in the 3–50 kDa molecular mass range. Between 50 and 160 kDa, 27 more peaks were detected. Conclusion Based on these results, SELDI-TOF MS may be a suitable high-throughput candidate for HDL protein profiling and marker search. This approach may be used to i investigate the underlying mechanisms that lead to increased atherothrombotic risk and ii to investigate the atherothrombotic state of an individual.

  5. High-Density Infrared Surface Treatments of Refractories

    Energy Technology Data Exchange (ETDEWEB)

    Tiegs, T.N.

    2005-03-31

    Refractory materials play a crucial role in all energy-intensive industries and are truly a crosscutting technology for the Industries of the Future (IOF). One of the major mechanisms for the degradation of refractories and a general decrease in their performance has been the penetration and corrosion by molten metals or glass. Methods and materials that would reduce the penetration, wetting, and corrosive chemistry would significantly improve refractory performance and also maintain the quality of the processed liquid, be it metal or glass. This report presents the results of an R&D project aimed at investigating the use of high-density infrared (HDI) heating to surface treat refractories to improve their performance. The project was a joint effort between Oak Ridge National Laboratory (ORNL) and the University of Missouri-Rolla (UMR). HDI is capable of heating the near-surface region of materials to very high temperatures where sintering, diffusion, and melting can occur. The intended benefits of HDI processing of refractories were to (1) reduce surface porosity (by essentially sealing the surface to prevent liquid penetration), (2) allow surface chemistry changes to be performed by bonding an adherent coating onto the underlying refractory (in order to inhibit wetting and/or improve corrosion resistance), and (3) produce noncontact refractories with high-emissivity surface coatings.

  6. Aircraft Carriers

    DEFF Research Database (Denmark)

    Nødskov, Kim; Kværnø, Ole

    There are many indications that China is actively researching the design of an aircraft carrier. It is unknown whether China will initiate the actual acquisition of a carrier, but the indications that are available of their research into aircraft carriers and carrier-capable aircraft, as well...... as their purchases of aircraft carrier systems, makes it more than likely that the country is preparing such an acquisition. China has territorial disputes in the South China Sea over the Spratly Islands and is also worried about the security of its sea lines of communications, by which China transports the majority...... of its foreign trade, as well as its oil imports, upon which the country is totally dependent. China therefore has good reasons for acquiring an aircraft carrier to enable it to protect its national interests. An aircraft carrier would also be a prominent symbol of China’s future status as a great power...

  7. High carrier mobility of CoPc wires based field-effect transistors using bi-layer gate dielectric

    Directory of Open Access Journals (Sweden)

    Murali Gedda

    2013-11-01

    Full Text Available Polyvinyl alcohol (PVA and anodized Al2O3 layers were used as bi-layer gate for the fabrication of cobalt phthalocyanine (CoPc wire base field-effect transistors (OFETs. CoPc wires were grown on SiO2 surfaces by organic vapor phase deposition method. These devices exhibit a field-effect carrier mobility (μEF value of 1.11 cm2/Vs. The high carrier mobility for CoPc molecules is attributed to the better capacitive coupling between the channel of CoPc wires and the gate through organic-inorganic dielectric layer. Our measurements also demonstrated the way to determine the thicknesses of the dielectric layers for a better process condition of OFETs.

  8. Single Carrier Cyclic Prefix-Assisted CDMA System with Frequency Domain Equalization for High Data Rate Transmission

    Directory of Open Access Journals (Sweden)

    Chin Francois

    2004-01-01

    Full Text Available Multiple-access interference and interfinger interference limit the capacity of conventional single-carrier DS-CDMA systems. Even though multicarrier CDMA posses the advantages of conventional CDMA and OFDM, it suffers from two major implementation difficulties such as peak-to-average power ratio and high sensitivity to frequency offset and RF phase noise. A novel approach based on single-carrier cyclic prefix-assisted CDMA has been proposed to overcome the disadvantages of single-carrier CDMA and multicarrier modulation. The usefulness of the proposed approach for high-speed packet access with simplified channel estimation procedures are investigated in this paper. The paper also proposes a data-dependent pilot structure for the downlink transmission of the proposed system for enhancing pilot-assisted channel estimation in frequency domain. The performance of the proposed pilot structure is compared against the data-independent common pilot structure. The proposed system is extensively simulated for different channel parameters with different channel estimation and equalization methods and the results are compared against conventional multicarrier CDMA systems with identical system specifications.

  9. Single Carrier Cyclic Prefix-Assisted CDMA System with Frequency Domain Equalization for High Data Rate Transmission

    Directory of Open Access Journals (Sweden)

    Madhukumar A. S.

    2004-01-01

    Full Text Available Multiple-access interference and interfinger interference limit the capacity of conventional single-carrier DS-CDMA systems. Even though multicarrier CDMA posses the advantages of conventional CDMA and OFDM, it suffers from two major implementation difficulties such as peak-to-average power ratio and high sensitivity to frequency offset and RF phase noise. A novel approach based on single-carrier cyclic prefix-assisted CDMA has been proposed to overcome the disadvantages of single-carrier CDMA and multicarrier modulation. The usefulness of the proposed approach for high-speed packet access with simplified channel estimation procedures are investigated in this paper. The paper also proposes a data-dependent pilot structure for the downlink transmission of the proposed system for enhancing pilot-assisted channel estimation in frequency domain. The performance of the proposed pilot structure is compared against the data-independent common pilot structure. The proposed system is extensively simulated for different channel parameters with different channel estimation and equalization methods and the results are compared against conventional multicarrier CDMA systems with identical system specifications.

  10. The indicating FTA elute cartridge a solid sample carrier to detect high-risk HPV and high-grade cervical lesions

    NARCIS (Netherlands)

    Bie, R.P. de; Schmeink, C.E.; Bakkers, J.M.J.E.; Snijders, P.J.L.M.; Quint, W.G.V.; Massuger, L.F.A.G.; Bekkers, R.L.M.; Melchers, W.J.G.

    2011-01-01

    The clinically validated high-risk human papillomavirus (hrHPV) Hybrid Capture 2 (HC2) and GP5+/6+-PCR assays were analyzed on an Indicating FTA Elute cartridge (FTA cartridge). The FTA cartridge is a solid dry carrier that allows safe transport of cervical samples. FTA cartridge samples were

  11. Urban malaria in the Brazilian Western Amazon Region I: high prevalence of asymptomatic carriers in an urban riverside district is associated with a high level of clinical malaria

    Directory of Open Access Journals (Sweden)

    Mauro Shugiro Tada

    2007-06-01

    Full Text Available Cross sectional studies on malaria prevalence was performed in 2001, 2002, and 2004 in Vila Candelária, an urban riverside area of Porto Velho, Rondônia, in the Brazilian Western Amazon, followed by longitudinal surveys on malaria incidence. Vila Candelária is a working class district, provided with electricity, water supply, and basic sanitation. Previous preliminary surveys indicated high malaria incidence in this community. At the end of year 2000 regular diagnostic and treatment measures for malaria were introduced, with active search of febrile cases among residents. Despite of both rapid treatment of cases and relative good sanitary and housing conditions, the malaria incidence persisted at high levels during the following years with an annual parasite index of 150 to 300/1000 inhabitants. Parasite surveys in 2001, 2002, and 2004 achieved through microscopy and polymerase chain reaction to diagnose malaria showed a constant high prevalence of asymptomatic carriers for both Plasmodium falciparum and P. vivax parasites. It was concluded that asymptomatic carriers represent an important reservoirs of parasites and that the carriers might contribute to maintaining the high level of transmission. Comparing our findings to similar geo-demographic situations found in other important urban communities of the Brazilian Amazon, we propose that asymptomatic carriers could explain malaria's outbreaks like the one recently observed in Manaus.

  12. First-principle theory of high field carrier transport in semiconductors with application to the study of avalanche photodiodes

    Science.gov (United States)

    Moresco, Michele

    2011-12-01

    The objective of this thesis work is twofold: to present a theoretical framework to study high-field carrier transport in semiconductor materials and to provide a deep understanding of the transport properties of GaN and HgCdTe. The validation of this model is performed by applying it to the study of Avalanche Photodiodes. The model we developed is based on Monte Carlo techniques and it includes the full details of the band structure, derived from the empirical pseudopotential method (EPM), and a numerically calculated impact ionization transition rate based on a wave-vector dependent dielectric function. The nonpolar carrier-phonon interaction is treated within the framework of the rigid pseudoion (RPI) approximation using ab initio techniques to determine the phonon dispersion relation. The calculated phonon scattering rates are consistent with the electronic structure and the phonon dispersion relation thus removing adjustable parameters such as deformation potential coefficients. Band-to-band carrier tunneling has been treated by solving the time-dependent multiband Schroedinger equation. The multiband description predicts a considerable increase of the impact ionization coefficients compared with simulations not considering tunneling. Specifically, the present model has been applied to the study of two distinct semiconductor materials: GaN and HgCdTe. The former is a wide bandgap while the second is a narrow bandgap semiconductor. In spite of their constantly increasing technological reliability both materials lack theoretical understanding of high-field carrier transport. Avalanche photodiodes (APDs) offer an ideal environment to test and validate the model developed in this thesis work because of the large electric field involved in these devices. APDs based on both GaN and HgCdTe are investigated, consistently with the physics-based models described above. Key quantities such as gain, breakdown voltage, bandwidth and noise characteristics are estimated. The

  13. Cyclic Oxidation of High Mo, Reduced Density Superalloys

    Directory of Open Access Journals (Sweden)

    James L. Smialek

    2015-11-01

    Full Text Available Cyclic oxidation was characterized as part of a statistically designed, 12-alloy compositional study of 2nd generation single crystal superalloys as part of a broader study to co-optimize density, creep strength, and cyclic oxidation. The primary modification was a replacement of 5 wt. % W by 7% or 12% Mo for density reductions of 2%–7%. Compositions at two levels of Mo, Cr, Co, and Re were produced, along with a midpoint composition. Initially, polycrystalline vacuum induction samples were screened in 1100 °C cyclic furnace tests using 1 h cycles for 200 h. The behavior was primarily delimited by Cr content, producing final weight changes of −40 mg/cm2 to −10 mg/cm2 for 0% Cr alloys and −2 mg/cm2 to +1 mg/cm2 for 5% Cr alloys. Accordingly, a multiple linear regression fit yielded an equation showing a strong positive Cr effect and lesser negative effects of Co and Mo. The results for 5% Cr alloys compare well to −1 mg/cm2, and +0.5 mg/cm2 for Rene′ N4 and Rene′ N5 (or Rene′ N6, respectively. Scale phases commonly identified were Al2O3, NiAl2O4, NiTa2O6, and NiO, with (Ni,CoMoO4 found only on the least resistant alloys having 0% Cr and 12% Mo. Scale microstructures were complex and reflected variations in the regional spallation history. Large faceted NiO grains and fine NiTa2O6 particles distributed along NiAl2O4 grain boundaries were typical distinctive features. NiMoO4 formation, decomposition, and volatility occurred for a few high Mo compositions. A creep, density, phase stability, and oxidation balanced 5% Cr, 10% Co, 7% Mo, and 3% Re alloy was selected to be taken forward for more extensive evaluations in single crystal form.

  14. A statin-loaded reconstituted high-density lipoprotein nanoparticle inhibits atherosclerotic plaque inflammation

    Science.gov (United States)

    Duivenvoorden, Raphaël; Tang, Jun; Cormode, David P.; Mieszawska, Aneta J.; Izquierdo-Garcia, David; Ozcan, Canturk; Otten, Maarten J.; Zaidi, Neeha; Lobatto, Mark E.; van Rijs, Sarian M.; Priem, Bram; Kuan, Emma L.; Martel, Catherine; Hewing, Bernd; Sager, Hendrik; Nahrendorf, Matthias; Randolph, Gwendalyn J.; Stroes, Erik S. G.; Fuster, Valentin; Fisher, Edward A.; Fayad, Zahi A.; Mulder, Willem J. M.

    2014-01-01

    Inflammation is a key feature of atherosclerosis and a target for therapy. Statins have potent anti-inflammatory properties but these cannot be fully exploited with oral statin therapy due to low systemic bioavailability. Here we present an injectable reconstituted high-density lipoprotein (rHDL) nanoparticle carrier vehicle that delivers statins to atherosclerotic plaques. We demonstrate the anti-inflammatory effect of statin-rHDL in vitro and show that this effect is mediated through the inhibition of the mevalonate pathway. We also apply statin-rHDL nanoparticles in vivo in an apolipoprotein E-knockout mouse model of atherosclerosis and show that they accumulate in atherosclerotic lesions in which they directly affect plaque macrophages. Finally, we demonstrate that a 3-month low-dose statin-rHDL treatment regimen inhibits plaque inflammation progression, while a 1-week high-dose regimen markedly decreases inflammation in advanced atherosclerotic plaques. Statin-rHDL represents a novel potent atherosclerosis nanotherapy that directly affects plaque inflammation.

  15. Effects of gamma irradiation on polypropylene, polypropylene + high density polyethylene and polypropylene + high density polyethylene + wood flour

    Energy Technology Data Exchange (ETDEWEB)

    Reyes, J.; Albano, C.; Davidson, E.; Poleo, R. [Universidad Central de Venezuela, Caracas (Venezuela). Escuela de Quimica; Gonzalez, J.; Ichazo, M. [Universidad Simon Bolivar, Dept. de Mecanica, Caracas (Venezuela); Chipara, M. [Research Institute for Electrotechnics, Bucharest (Romania)

    2001-04-01

    The effect of the gamma-irradiation on the mechanical properties of the composites, Polypropylene (PP), PP+high density Polyethylene (HDPE), PP+ HDPE+wood flour, where HDPE is virgin and recycled, was studied. This paper discusses the behavior of the composites after exposure to various doses of gamma irradiation (1-7 MRads) in the presence of oxygen. The dependence of mechanical properties on the integral dose for a constant dose rate of 0.48 MRads/h confirms the influence of the irradiation. Strong effects on the elongation at break and break strength is noticed. The mathematical analysis suggests for the PP+r-HDPE a bimolecular process of the elongation at break. On the order hand, for the PP+HDPE a complex process is represented for a three exponential equation. (orig.)

  16. Individual tree detection based on densities of high points of high resolution airborne lidar

    NARCIS (Netherlands)

    Abd Rahman, M.Z.; Gorte, B.G.H.

    2008-01-01

    The retrieval of individual tree location from Airborne LiDAR has focused largely on utilizing canopy height. However, high resolution Airborne LiDAR offers another source of information for tree detection. This paper presents a new method for tree detection based on high points’ densities from a

  17. Tree crown delineation from high resolution airborne LiDAR based on densities of high points

    NARCIS (Netherlands)

    Rahman, M.Z.A.; Gorte, B.G.H.

    2009-01-01

    Tree detection and tree crown delineation from Airborne LiDAR has been focusing mostly on utilizing the canopy height model (CHM). This paper presents a method for individual tree crown delineation based on densities of high points (DHP) from the high resolution Airborne LiDAR. The DHP method relies

  18. A theory of density-of-states effective masses in heavily doped silicon at high temperatures and its applications

    Science.gov (United States)

    Van Cong, H.

    2007-01-01

    A theory of density-of-states effective masses in the n(p)-type heavily doped silicon at high temperatures, T, was developed, taking into account the effects of nonparabolicity in the band and Fermi-Dirac statistics. It was applied to determine the intrinsic carrier density at 200⩽ T (K)⩽500 accurate to within 4.8%, and at 300 K semi-empirical forms for band gap narrowing (BGN) and apparent BGN with an accuracy of 17% and for optical gap with a precision of 1%, giving rise to a satisfactory description of both electrical and optical data. Furthermore, at 280⩽ T (K)⩽400, the BGN can be assumed to be T-independent, with a precision of 8.8%.

  19. High-density myoelectric pattern recognition toward improved stroke rehabilitation.

    Science.gov (United States)

    Zhang, Xu; Zhou, Ping

    2012-06-01

    Myoelectric pattern-recognition techniques have been developed to infer user's intention of performing different functional movements. Thus electromyogram (EMG) can be used as control signals of assisted devices for people with disabilities. Pattern-recognition-based myoelectric control systems have rarely been designed for stroke survivors. Aiming at developing such a system for improved stroke rehabilitation, this study assessed detection of the affected limb's movement intention using high-density surface EMG recording and pattern-recognition techniques. Surface EMG signals comprised of 89 channels were recorded from 12 hemiparetic stroke subjects while they tried to perform 20 different arm, hand, and finger/thumb movements involving the affected limb. A series of pattern-recognition algorithms were implemented to identify the intended tasks of each stroke subject. High classification accuracies (96.1% ± 4.3%) were achieved, indicating that substantial motor control information can be extracted from paretic muscles of stroke survivors. Such information may potentially facilitate improved stroke rehabilitation.

  20. High-Density Carbon (HDC) Ablator for NIC Ignition Capsules

    Science.gov (United States)

    Ho, D.; Haan, S.; Salmonson, J.; Milovich, J.; Callahan, D.

    2012-10-01

    HDC ablators show high performance based on simulations, despite the fact that the shorter pulses for HDC capsules result in higher M-band radiation compared to that for plastic capsules. HDC capsules have good 1-D performance because HDC has relatively high density (3.5 g/cc), which results in a thinner ablator that absorbs more radiation. HDC ablators have good 2-D performance because the ablator surface is more than an order-of-magnitude smoother than Be or plastic ablators. Refreeze of the ablator near the fuel region can be avoided by appropriate dopant placement. Here we present two HDC ignition designs doped with W and Si. For the design with maximum W concentration of 1.0 at% (and respectively with maximum Si concentration of 2.0 at%): peak velocity = 0.395 (0.397) mm/ns, mass weighted fuel entropy = 0.463 (0.469) kJ/mg/eV, peak core hydrodynamic stagnation pressure = 690 (780) Gbar, and yield = 17.3 (20.2) MJ. 2-D simulations show that yield is close to 80% YoC even with 2.5x of nominal surface roughness on all surfaces. The clean fuel fraction is about 75% at peak velocity. Doping HDC with the required concentration of W and Si is in progress. A first undoped HDC Symcap is scheduled to be fielded later this year.

  1. Alcohol consumption, TaqIB polymorphism of cholesteryl ester transfer protein, high-density lipoprotein cholesterol, and risk of coronary heart disease in men and women

    DEFF Research Database (Denmark)

    Jensen, Majken K; Mukamal, Kenneth J; Overvad, Kim;

    2008-01-01

    AIMS: To investigate whether a common polymorphism in the cholesteryl ester transfer protein (CETP) gene modifies the relationship of alcohol intake with high-density lipoprotein cholesterol (HDL-C) and risk of coronary heart disease (CHD). METHODS AND RESULTS: Parallel nested case-control studies...... among women [Nurses' Health Study (NHS)] and men [Health Professionals Follow-up Study (HPFS)] where 246 women and 259 men who developed incident CHD were matched to controls (1:2) on age and smoking. The TaqIB variant and alcohol consumption were associated with higher HDL-C, with the most pronounced...... effects of alcohol among B2 carriers. In the NHS we did not find an inverse association between alcohol and CHD in B2 non-carriers (P trend: 0.5), but did among B2 carriers (P trend

  2. Towards high charge carrier mobilities by rational design of organic semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Andrienko, Denis; Ruehle, Victor; Baumeier, Bjoern; Vehoff, Thorsten; Lukyanov, Alexander; Kremer, Kurt [Max Planck Institute for Polymer Research, Mainz (Germany); Marcon, Valentina [Technische Universitaet Darmstadt (Germany); Kirkpatrick, James; Nelson, Jenny [Imperial College London (United Kingdom); Lennartz, Christian [BASF AG, Ludwigshafen (Germany)

    2010-07-01

    The role of material morphology on charge carrier mobility in partially disordered organic semiconductors is discussed for several classes of materials: derivatives of hexabenzocoronenens, perylenediimides, triangularly-shaped polyaromatic hydrocarbons, and Alq{sub 3}. Simulations are performed using a package developed by Imperial College, London and Max Planck Institute for Polymer Research, Mainz (votca.org). This package combines several techniques into one scheme: quantum chemical methods for the calculation of molecular electronic structures and reorganization energies; molecular dynamics and systematic coarse-graining approaches for simulation of self-assembly and relative positions and orientations of molecules on large scales; kinetic Monte Carlo and master equation for studies of charge transport.

  3. Measurement of high carrier mobility in graphene in an aqueous electrolyte environment

    Science.gov (United States)

    Brown, Morgan A.; Crosser, Michael S.; Leyden, Matthew R.; Qi, Yabing; Minot, Ethan D.

    2016-08-01

    Graphene is a promising material for applications in aqueous electrolyte environments. To explore the impact of such environments on graphene's electrical properties, we performed Hall bar measurements on electrolyte-gated graphene. Assuming a Drude model, we find that the room temperature carrier mobility in water-gated, SiO2-supported graphene reaches 7000 cm2/Vs, comparable to the best dry SiO2-supported graphene devices. Our results show that the electrical performance of graphene is robust, even in the presence of dissolved ions that introduce an additional mechanism for Coulomb scattering.

  4. Clock and carrier recovery in high-speed coherent optical communication systems

    Science.gov (United States)

    Amado, Sofia B.; Ferreira, Ricardo; Costa, Pedro S.; Guiomar, Fernando P.; Ziaie, Somayeh; Teixeira, António L.; Muga, Nelson J.; Pinto, Armando N.

    2014-08-01

    In this paper, the implementations of clock and carrier recovery in digital domain are analyzed. Hardware implementation details, resources estimation and real-time results are presented. Analog-to-Digital Converters (ADC), operating at 1.25Gsa/s, and a Virtex-6 Field-Programmable Gate Array (FPGA), have been used, allowing the implementation of a real-time Quadrature Phase Shift Keying (QPSK) system operating at 1.25Gb/s. The real-time mode operation is successfully demonstrated over 80 km of Standard Single Mode Fiber (SSMF).

  5. Altered activation of endothelial anti- and proapoptotic pathways by high-density lipoprotein from patients with coronary artery disease: role of high-density lipoprotein-proteome remodeling

    National Research Council Canada - National Science Library

    Riwanto, Meliana; Rohrer, Lucia; Roschitzki, Bernd; Besler, Christian; Mocharla, Pavani; Mueller, Maja; Perisa, Damir; Heinrich, Kathrin; Altwegg, Lukas; von Eckardstein, Arnold; Lüscher, Thomas F; Landmesser, Ulf

    2013-01-01

    ...). High-density lipoprotein from healthy subjects (HDL(Healthy)) has been proposed to exert endothelial antiapoptotic effects that may represent an important antiatherogenic property of the lipoprotein...

  6. Correlation between Photoluminescence and Carrier Transport and a Simple In Situ Passivation Method for High-Bandgap Hybrid Perovskites.

    Science.gov (United States)

    Stoddard, Ryan J; Eickemeyer, Felix T; Katahara, John K; Hillhouse, Hugh W

    2017-07-20

    High-bandgap mixed-halide hybrid perovskites have higher open-circuit voltage deficits and lower carrier diffusion lengths than their lower-bandgap counterparts. We have developed a ligand-assisted crystallization (LAC) technique that introduces additives in situ during the solvent wash and developed a new method to dynamically measure the absolute intensity steady-state photoluminescence and the mean carrier diffusion length simultaneously. The measurements reveal four distinct regimes of material changes and show that photoluminescence brightening often coincides with losses in carrier transport, such as in degradation or phase segregation. Further, the measurements enabled optimization of LAC on the 1.75 eV bandgap FA0.83Cs0.17Pb(I0.66Br0.34)3, resulting in an enhancement of the photoluminescence quantum yield (PLQY) of over an order of magnitude, an increase of 80 meV in the quasi-Fermi level splitting (to 1.29 eV), an increase in diffusion length by a factor of 3.5 (to over 1 μm), and enhanced open-circuit voltage and short-circuit current from photovoltaics fabricated from the LAC-treated films.

  7. Optimizing the Dopant and Carrier Concentration of Ca5Al2Sb6 for High Thermoelectric Efficiency

    Science.gov (United States)

    Yan, Yuli; Zhang, Guangbiao; Wang, Chao; Peng, Chengxiao; Zhang, Peihong; Wang, Yuanxu; Ren, Wei

    2016-01-01

    The effects of doping on the transport properties of Ca5Al2Sb6 are investigated using first-principles electronic structure methods and Boltzmann transport theory. The calculated results show that a maximum ZT value of 1.45 is achieved with an optimum carrier concentration at 1000 K. However, experimental studies have shown that the maximum ZT value is no more than 1 at 1000 K. By comparing the calculated Seebeck coefficient with experimental values, we find that the low dopant solubility in this material is not conductive to achieve the optimum carrier concentration, leading a smaller experimental value of the maximum ZT. Interestingly, the calculated dopant formation energies suggest that optimum carrier concentrations can be achieved when the dopants and Sb atoms have similar electronic configurations. Therefore, it might be possible to achieve a maximum ZT value of 1.45 at 1000 K with suitable dopants. These results provide a valuable theoretical guidance for the synthesis of high-performance bulk thermoelectric materials through dopants optimization. PMID:27406178

  8. Symmetry energy systematics and its high density behavior

    CERN Document Server

    Chen, Lie-Wen

    2015-01-01

    We explore the systematics of the density dependence of nuclear matter symmetry energy in the ambit of microscopic calculations with various energy density functionals, and find that the symmetry energy from subsaturation density to supra-saturation density can be well determined by three characteristic parameters of the symmetry energy at saturation density $\\rho_0 $, i.e., the magnitude $E_{\\text{sym}}({\\rho_0 })$, the density slope $L$ and the density curvature $K_{\\text{sym}}$. This finding opens a new window to constrain the supra-saturation density behavior of the symmetry energy from its (sub-)saturation density behavior. In particular, we obtain $L=46.7 \\pm 12.8$ MeV and $K_{\\text{sym}}=-166.9 \\pm 168.3$ MeV as well as $E_{\\text{sym}}({2\\rho _{0}}) \\approx 40.2 \\pm 12.8$ MeV and $L({2\\rho _{0}}) \\approx 8.9 \\pm 108.7$ MeV based on the present knowledge of $E_{\\text{sym}}({\\rho_{0}}) = 32.5 \\pm 0.5$ MeV, $E_{\\text{sym}}({\\rho_c}) = 26.65 \\pm 0.2$ MeV and $L({\\rho_c}) = 46.0 \\pm 4.5$ MeV at $\\rho_{\\rm{c...

  9. High-density lipoprotein proteome dynamics in human endotoxemia

    Directory of Open Access Journals (Sweden)

    Stroes Erik SG

    2011-06-01

    Full Text Available Abstract Background A large variety of proteins involved in inflammation, coagulation, lipid-oxidation and lipid metabolism have been associated with high-density lipoprotein (HDL and it is anticipated that changes in the HDL proteome have implications for the multiple functions of HDL. Here, SELDI-TOF mass spectrometry (MS was used to study the dynamic changes of HDL protein composition in a human experimental low-dose endotoxemia model. Ten healthy men with low HDL cholesterol (0.7+/-0.1 mmol/L and 10 men with high HDL cholesterol levels (1.9+/-0.4 mmol/L were challenged with endotoxin (LPS intravenously (1 ng/kg bodyweight. We previously showed that subjects with low HDL cholesterol are more susceptible to an inflammatory challenge. The current study tested the hypothesis that this discrepancy may be related to differences in the HDL proteome. Results Plasma drawn at 7 time-points over a 24 hour time period after LPS challenge was used for direct capture of HDL using antibodies against apolipoprotein A-I followed by subsequent SELDI-TOF MS profiling. Upon LPS administration, profound changes in 21 markers (adjusted p-value Conclusions This study shows that the semi-quantitative differences in the HDL proteome as assessed by SELDI-TOF MS cannot explain why subjects with low HDL cholesterol are more susceptible to a challenge with LPS than those with high HDL cholesterol. Instead the results indicate that hierarchical clustering could be useful to predict HDL functionality in acute phase responses towards LPS.

  10. High density plasmas and new diagnostics: An overview (invited)

    Energy Technology Data Exchange (ETDEWEB)

    Celona, L., E-mail: celona@lns.infn.it; Gammino, S.; Mascali, D. [Istituto Nazionale di Fisica Nucleare—Laboratori Nazionali del Sud, Via S. Sofia 62, 95123 Catania (Italy)

    2016-02-15

    One of the limiting factors for the full understanding of Electron Cyclotron Resonance Ion Sources (ECRISs) fundamental mechanisms consists of few types of diagnostic tools so far available for such compact machines. Microwave-to-plasma coupling optimisation, new methods of density overboost provided by plasma wave generation, and magnetostatic field tailoring for generating a proper electron energy distribution function, suitable for optimal ion beams formation, require diagnostic tools spanning across the entire electromagnetic spectrum from microwave interferometry to X-ray spectroscopy; these methods are going to be implemented including high resolution and spatially resolved X-ray spectroscopy made by quasi-optical methods (pin-hole cameras). The ion confinement optimisation also requires a complete control of cold electrons displacement, which can be performed by optical emission spectroscopy. Several diagnostic tools have been recently developed at INFN-LNS, including “volume-integrated” X-ray spectroscopy in low energy domain (2-30 keV, by using silicon drift detectors) or high energy regime (>30 keV, by using high purity germanium detectors). For the direct detection of the spatially resolved spectral distribution of X-rays produced by the electronic motion, a “pin-hole camera” has been developed also taking profit from previous experiences in the ECRIS field. The paper will give an overview of INFN-LNS strategy in terms of new microwave-to-plasma coupling schemes and advanced diagnostics supporting the design of new ion sources and for optimizing the performances of the existing ones, with the goal of a microwave-absorption oriented design of future machines.

  11. High density plasmas and new diagnostics: An overview (invited).

    Science.gov (United States)

    Celona, L; Gammino, S; Mascali, D

    2016-02-01

    One of the limiting factors for the full understanding of Electron Cyclotron Resonance Ion Sources (ECRISs) fundamental mechanisms consists of few types of diagnostic tools so far available for such compact machines. Microwave-to-plasma coupling optimisation, new methods of density overboost provided by plasma wave generation, and magnetostatic field tailoring for generating a proper electron energy distribution function, suitable for optimal ion beams formation, require diagnostic tools spanning across the entire electromagnetic spectrum from microwave interferometry to X-ray spectroscopy; these methods are going to be implemented including high resolution and spatially resolved X-ray spectroscopy made by quasi-optical methods (pin-hole cameras). The ion confinement optimisation also requires a complete control of cold electrons displacement, which can be performed by optical emission spectroscopy. Several diagnostic tools have been recently developed at INFN-LNS, including "volume-integrated" X-ray spectroscopy in low energy domain (2-30 keV, by using silicon drift detectors) or high energy regime (>30 keV, by using high purity germanium detectors). For the direct detection of the spatially resolved spectral distribution of X-rays produced by the electronic motion, a "pin-hole camera" has been developed also taking profit from previous experiences in the ECRIS field. The paper will give an overview of INFN-LNS strategy in terms of new microwave-to-plasma coupling schemes and advanced diagnostics supporting the design of new ion sources and for optimizing the performances of the existing ones, with the goal of a microwave-absorption oriented design of future machines.

  12. Ultra-high Density SNParray in Neuroblastoma Molecular Diagnostics

    Directory of Open Access Journals (Sweden)

    Inge M. Ambros

    2014-08-01

    Full Text Available Neuroblastoma serves as a paradigm for applying tumor genomic data for determining patient prognosis and thus for treatment allocation. MYCN status, i.e. amplified vs. non-amplified, was one of the very first biomarkers in oncology to discriminate aggressive from less aggressive or even favorable clinical courses of neuroblastoma. However, MYCN amplification is by far not the only genetic change associated with unfavorable clinical courses: so called segmental chromosomal aberrations, i.e. gains or losses of chromosomal fragments, can also indicate tumor aggressiveness. The clinical use of these genomic aberrations has, however, been hampered for many years by methodical and interpretational problems. Only after reaching worldwide consensus on markers, methodology, and data interpretation, information on SCAs has recently been implemented in clinical studies. Now, a number of collaborative studies within COG, GPOH and SIOPEN use genomic information to stratify therapy for patients with localized and metastatic disease. Recently, new types of DNA based aberrations influencing the clinical behavior of neuroblastomas have been described. Deletions or mutations of genes like ATRX and a phenomenon referred to as chromothripsis are all assumed to correlate with an unfavorable clinical behavior. However, these genomic aberrations need to be scrutinized in larger studies applying the most appropriate techniques. Single nucleotide polymorphism (SNP arrays have proven successful in deciphering genomic aberrations of cancer cells; these techniques, however, are usually not applied in the daily routine. Here, we present an ultra-high density (UHD SNParray technique which is, because of its high specificity and sensitivity and the combined copy number and allele information, highly appropriate for the genomic diagnosis of neuroblastoma and other malignancies.

  13. Plasma behaviour at high beta and high density in the Madison Symmetric Torus RFP

    Energy Technology Data Exchange (ETDEWEB)

    Wyman, M. [University of Wisconsin, Madison; Chapman, B. E. [University of Wisconsin, Madison; Ahn, J. W. [University of Wisconsin, Madison; Almagri, A. F. [University of Wisconsin, Madison; Anderson, J. [University of Wisconsin, Madison; Bonomo, F. [Consorzio RFX, Italy; Bower, D L [University of California, Los Angeles; Combs, Stephen Kirk [ORNL; Craig, D. [University of Wisconsin, Madison; Foust, Charles R [ORNL

    2009-01-01

    Pellet fuelling of improved confinement Madison Symmetric Torus (MST) plasmas has resulted in high density and high plasma beta. The density in improved confinement discharges has been increased fourfold, and a record plasma beta (beta(tot) = 26%) for the improved confinement reversed-field pinch (RFP) has been achieved. At higher beta, a new regime for instabilities is accessed in which local interchange and global tearing instabilities are calculated to be linearly unstable, but experimentally, no severe effect, e. g., a disruption, is observed. The tearing instability, normally driven by the current gradient, is driven by the pressure gradient in this case, and there are indications of increased energy transport ( as compared with low-density improved confinement). Pellet fuelling is also compared with enhanced edge fuelling of standard confinement RFP discharges for the purpose of searching for a density limit in MST. In standard-confinement discharges, pellet fuelling peaks the density profile where edge fuelling cannot, but transport appears unchanged. For a limited range of plasma current, MST discharges with edge fuelling are constrained to a maximum density corresponding to the Greenwald limit. This limit is surpassed in pellet-fuelled improved confinement discharges.

  14. Fundamental properties of high-quality carbon nanofoam: from low to high density

    Directory of Open Access Journals (Sweden)

    Natalie Frese

    2016-12-01

    Full Text Available Highly uniform samples of carbon nanofoam from hydrothermal sucrose carbonization were studied by helium ion microscopy (HIM, X-ray photoelectron spectroscopy (XPS, and Raman spectroscopy. Foams with different densities were produced by changing the process temperature in the autoclave reactor. This work illustrates how the geometrical structure, electron core levels, and the vibrational signatures change when the density of the foams is varied. We find that the low-density foams have very uniform structure consisting of micropearls with ≈2–3 μm average diameter. Higher density foams contain larger-sized micropearls (≈6–9 μm diameter which often coalesced to form nonspherical μm-sized units. Both, low- and high-density foams are comprised of predominantly sp2-type carbon. The higher density foams, however, show an advanced graphitization degree and a stronger sp3-type electronic contribution, related to the inclusion of sp3 connections in their surface network.

  15. Interfacial Study To Suppress Charge Carrier Recombination for High Efficiency Perovskite Solar Cells.

    Science.gov (United States)

    Adhikari, Nirmal; Dubey, Ashish; Khatiwada, Devendra; Mitul, Abu Farzan; Wang, Qi; Venkatesan, Swaminathan; Iefanova, Anastasiia; Zai, Jiantao; Qian, Xuefeng; Kumar, Mukesh; Qiao, Qiquan

    2015-12-09

    We report effects of an interface between TiO2-perovskite and grain-grain boundaries of perovskite films prepared by single step and sequential deposited technique using different annealing times at optimum temperature. Nanoscale kelvin probe force microscopy (KPFM) measurement shows that charge transport in a perovskite solar cell critically depends upon the annealing conditions. The KPFM results of single step and sequential deposited films show that the increase in potential barrier suppresses the back-recombination between electrons in TiO2 and holes in perovskite. Spatial mapping of the surface potential within perovskite film exhibits higher positive potential at grain boundaries compared to the surface of the grains. The average grain boundary potential of 300-400 mV is obtained upon annealing for sequentially deposited films. X-ray diffraction (XRD) spectra indicate the formation of a PbI2 phase upon annealing which suppresses the recombination. Transient analysis exhibits that the optimum device has higher carrier lifetime and short carrier transport time among all devices. An optimum grain boundary potential and proper band alignment between the TiO2 electron transport layer (ETL) and the perovskite absorber layer help to increase the overall device performance.

  16. High energy density interpenetrating networks from ionic networks and silicone

    DEFF Research Database (Denmark)

    Yu, Liyun; Madsen, Frederikke Bahrt; Hvilsted, Søren;

    2015-01-01

    The energy density of dielectric elastomers (DEs) is sought increased for better exploitation of the DE technology since an increased energy density means that the driving voltage for a certain strain can be lowered in actuation mode or alternatively that more energy can be harvested in generator...

  17. Matter composition at high density by effective scaled lagrangian

    Energy Technology Data Exchange (ETDEWEB)

    Hyun, Chang Ho; Min, Dong Pil [Dept. of Physics, Seoul National Univ., Seoul (Korea, Republic of)

    1998-06-01

    We investigate the matter composition at around the neutron star densities with a model lagrangian satisfying Brown-Rho scaling law. We calculate the neutron star properties such as maximum mass, radius, hyperon compositions and central density. We compare our results with those of Walecka model. (orig.)

  18. Calvarial reconstruction using high-density porous polyethylene cranial hemispheres

    Directory of Open Access Journals (Sweden)

    Nitin J Mokal

    2011-01-01

    Full Text Available Aims: Cranial vault reconstruction can be performed with a variety of autologous or alloplastic materials. We describe our experience using high-density porous polyethylene (HDPE cranial hemisphere for cosmetic and functional restoration of skull defects. The porous nature of the implant allows soft tissue ingrowth, which decreases the incidence of infection. Hence, it can be used in proximity to paranasal sinuses and where previous alloplastic cranioplasties have failed due to implant infection. Materials and Methods: We used the HDPE implant in seven patients over a three-year period for reconstruction of moderate to large cranial defects. Two patients had composite defects, which required additional soft tissue in the form of free flap and tissue expansion. Results: In our series, decompressive craniectomy following trauma was the commonest aetiology and all defects were located in the fronto-parieto-temporal region. The defect size was 10 cm on average in the largest diameter. All patients had good post-operative cranial contour and we encountered no infections, implant exposure or implant migration. Conclusions: Our results indicate that the biocompatibility and flexibility of the HDPE cranial hemisphere implant make it an excellent alternative to existing methods of calvarial reconstruction.

  19. Stability of discoidal high-density lipoprotein particles

    Science.gov (United States)

    Maleki, Mohsen; Fried, Eliot

    Motivated by experimental and numerical studies revealing that discoidal high-density lipoprotein (HDL) particles may adopt flat elliptical and nonplanar saddle-like configurations, it is hypothesized that these might represent stabilized configurations of initially unstable flat circular particles. A variational description is developed to explore the stability of a flat circular discoidal HDL particle. While the lipid bilayer is modeled as two-dimensional fluid film endowed with surface tension and bending elasticity, the apoA-I belt is modeled as one-dimensional inextensible twist-free chain endowed with bending elasticity. Stability is investigated using the second variation of the underlying energy functional. Various planar and nonplanar instability modes are predicted and corresponding nondimensional critical values of salient dimensionless parameters are obtained. The results predict that the first planar and nonplanar unstable modes occur due to in-plane elliptical and transverse saddle-like perturbations. Based on available data, detailed stability diagrams indicate the range of input parameters for which a flat circular discoidal HDL particle is linearly stable or unstable.

  20. High-density matter: current status and future challenges

    Science.gov (United States)

    Stone, J. R.

    2015-05-01

    There are many fascinating processes in the Universe which we observe in more and more in detail thanks to increasingly sophisticated technology. One of the most interesting phenomena is the life cycle of stars, their birth, evolution and death. If the stars are massive enough, they end their lives in the core-collapse supernova explosion, the one of the most violent events in the Universe. As the result, the densest objects in the Universe, neutron stars and/or black holes are created. Naturally, the physical basis of these events should be understood in line with observation. The current status of our knowledge of processes in the life of stars is far from adequate for their true understanding. We show that although many models have been constructed their detailed ability to describe observations is limited or non-existent. Furthermore the general failure of all models means that we cannot tell which are heading in the right direction. A possible way forward in modeling of high-density matter is outlined, exemplified by the quark-meson-coupling model (QMC). This model has a natural explanation for the saturation of nuclear forces and depends on very few adjustable parameters, strongly constrained by the underlying physics. Latest QMC results for compact objects and finite nuclei are presented.

  1. Properties of Raphia Palm Interspersed Fibre Filled High Density Polyethylene

    Directory of Open Access Journals (Sweden)

    Henry C. Obasi

    2013-01-01

    Full Text Available Blends of nonbiodegradable and biodegradable polymers can promote a reduction in the volume of plastic waste when they undergo partial degradation. In this study, properties of raphia palm interspersed fibre (RPIF filled high density polyethylene (HDPE have been investigated at different levels of filler loadings, 0 to 60 wt.%. Maleic anhydride-graft polyethylene was used as a compatibilizer. Raphia palm interspersed fibre was prepared by grinding and sieved to a particle size of 150 µm. HDPE blends were prepared in a corotating twin screw extruder. Results showed that the tensile strength and elongation at break of the blends decreased with increase in RPI loadings and addition of MA-g-PE was found to improve these properties. However, the Young’s modulus increased with increase in the amount of RPI into HDPE and compatibilization further increased the Young’s modulus. The water absorption indices and weight loss for RPI/HDPE composites were found to increase with RPI loadings but were decreased on addition of MA-g-PE.

  2. Anti-Viral Antibody Profiling by High Density Protein Arrays

    Science.gov (United States)

    Bian, Xiaofang; Wiktor, Peter; Kahn, Peter; Brunner, Al; Khela, Amritpal; Karthikeyan, Kailash; Barker, Kristi; Yu, Xiaobo; Magee, Mitch; Wasserfall, Clive H.; Gibson, David; Rooney, Madeleine E; Qiu, Ji; LaBaer, Joshua

    2015-01-01

    Viral infections elicit anti-viral antibodies and have been associated with various chronic diseases. Detection of these antibodies can facilitate diagnosis, treatment of infection and understanding of the mechanisms of virus associated diseases. In this work, we assayed anti-viral antibodies using a novel high density-nucleic acid programmable protein array (HD-NAPPA) platform. Individual viral proteins were expressed in situ directly from plasmids encoding proteins in an array of microscopic reaction chambers. Quality of protein display and serum response was assured by comparing intra- and inter- array correlation within or between printing batches with average correlation coefficients of 0.91 and 0.96, respectively. HD-NAPPA showed higher signal to background (S/B) ratio compared with standard NAPPA on planar glass slides and ELISA. Antibody responses to 761 antigens from 25 different viruses were profiled among patients with juvenile idiopathic arthritis (JIA) and type 1 diabetes (T1D). Common as well as unique antibody reactivity patterns were detected between patients and healthy controls. We believe HD-viral-NAPPA will enable the study of host-pathogen interactions at unprecedented dimensions and elucidate the role of pathogen infections in disease development. PMID:25758251

  3. High-density matter: current status and future challenges

    Directory of Open Access Journals (Sweden)

    Stone J. R.

    2015-01-01

    Full Text Available There are many fascinating processes in the Universe which we observe in more and more in detail thanks to increasingly sophisticated technology. One of the most interesting phenomena is the life cycle of stars, their birth, evolution and death. If the stars are massive enough, they end their lives in the core-collapse supernova explosion, the one of the most violent events in the Universe. As the result, the densest objects in the Universe, neutron stars and/or black holes are created. Naturally, the physical basis of these events should be understood in line with observation. The current status of our knowledge of processes in the life of stars is far from adequate for their true understanding. We show that although many models have been constructed their detailed ability to describe observations is limited or non-existent. Furthermore the general failure of all models means that we cannot tell which are heading in the right direction. A possible way forward in modeling of high-density matter is outlined, exemplified by the quark-meson-coupling model (QMC. This model has a natural explanation for the saturation of nuclear forces and depends on very few adjustable parameters, strongly constrained by the underlying physics. Latest QMC results for compact objects and finite nuclei are presented.

  4. Effect of substrates on crystallization of high density polyethylene

    Institute of Scientific and Technical Information of China (English)

    范毓润; 林渊; 阮绵照

    2008-01-01

    The experimental observations about remarkable influence of the substrates on the isothermal crystallization rate of a high density polyethylene(HDPE) were presented.Two methods were used to characterize the crystallization rate:the change of turbidity of the HDPE specimen and the changes of the complex viscosity and storage modulus measured by a rotational rheometer,which gave consistent results showing that the isothermal crystallization rate decreased in sequence as the specimen contacted with aluminum,brass and stainless steel plates,respectively.As to the dominant influence factor,the chemical composition of the substrates can be excluded via insulating the plate by an aluminum foil.Instead,we propose the plate’s ability of removing the latent heat of crystallization from the specimen.Rheological measurement is sensitive to the crystallization process.The colloid like model proposed by BOUTAHAR et al for the crystallization of HDPE gives reasonable predictions of the crystallized fraction from the measured storage modulus.

  5. Upgrading of biorenewables to high energy density fuels

    Energy Technology Data Exchange (ETDEWEB)

    Gordon, John C [Los Alamos National Laboratory; Batista, Enrique R [Los Alamos National Laboratory; Chen, Weizhong [Los Alamos National Laboratory; Currier, Robert P [Los Alamos National Laboratory; Dirmyer, Matthew R [Los Alamos National Laboratory; John, Kevin D [Los Alamos National Laboratory; Kim, Jin K [Los Alamos National Laboratory; Keith, Jason [Los Alamos National Laboratory; Martin, Richard L [Los Alamos National Laboratory; Pierpont, Aaron W [Los Alamos National Laboratory; Silks Ill, L. A. " " Pete [Los Alamos National Laboratory; Smythe, Mathan C [Los Alamos National Laboratory; Sutton, Andrew D [Los Alamos National Laboratory; Taw, Felicia L [Los Alamos National Laboratory; Trovitch, Ryan J [Los Alamos National Laboratory; Vasudevan, Kalyan V [Los Alamos National Laboratory; Waidmann, Christopher R [Los Alamos National Laboratory; Wu, Ruilian [Los Alamos National Laboratory; Baker, R. Thomas [UNIV OF OTTAWWA; Schlaf, Marcel [UNIV OF GUELPH

    2010-12-07

    According to a recent report, lignocellulose is the most abundant renewable biological resource on earth, with an annual production of {approx} 200 x 10{sup 9} tons. Conversion of lignocellulosics derived from wood, agricultural wastes, and woody grasses into liquid fuels and value-added chemical feedstocks is an active area of research that has seen an explosion of effort due to the need to replace petroleum based sources. The carbohydrates D-glucose (C{sub 6}), L-arabinose (C{sub 5}), and D-xylose (C{sub 5}) are readily obtained from the hydrolysis of lignocellulose and constitute the most abundant renewable organic carbon source on the planet. Because they are naturally produced on such a large scale, these sugars have the greatest potential to displace petrochemical derived transportation fuel. Recent efforts in our laboratories aimed towards the production of high energy density transportation fuels from carbohydrates have been structured around the parameters of selective carbohydrate carbon chain extension chemistries, low reaction temperatures, and the desired use of water or neat substrate as the solvent. Some of our efforts in this regard will be presented.

  6. Nuclear isomers as ultra-high-energy-density materials

    Science.gov (United States)

    Poppe, C. H.; Weiss, M. S.; Anderson, J. D.

    1992-09-01

    A major energy advance could result if the enormous potential of nuclear energy storage could be tapped without the penalty of radioactive by-products. Recent research has uncovered a new method for nuclear energy storage with high energy density and no residual radioactivity. Nuclear isomers are metastable states of atomic nuclei which release their energy in a prompt burst of electromagnetic radiation; in many cases the product remaining after decay of isomer is stable and no activity is produced by the electromagnetic decay. Two kinds of nuclear isomers are known: spin isomers and shape isomers. The former lacks a release mechanism. Theory has predicted the existence of shape isomers in the mass range around mercury and gold where decay by fission is prohibited. Experiments on the existence of fissionless shape isomers have resulted in evidence for 27 different shape isomers in isotopes of mercury, lead, and thallium. Three potential candidates for release mechanisms have been identified to date: neutron catalysis (Hf- 178), laser-electron-nuclear coupling (Th-229), and Stark-shift-induced mixing (speculative). Ways of producing nonfissioning shape isomers are discussed.

  7. High Density Lipoprotein: A Therapeutic Target in Type 2 Diabetes

    Directory of Open Access Journals (Sweden)

    Philip J. Barter

    2013-09-01

    Full Text Available High density lipoproteins (HDLs have a number of properties that have the potential to inhibit the development of atherosclerosis and thus reduce the risk of having a cardiovascular event. These protective effects of HDLs may be reduced in patients with type 2 diabetes, a condition in which the concentration of HDL cholesterol is frequently low. In addition to their potential cardioprotective properties, HDLs also increase the uptake of glucose by skeletal muscle and stimulate the synthesis and secretion of insulin from pancreatic β cells and may thus have a beneficial effect on glycemic control. This raises the possibility that a low HDL concentration in type 2 diabetes may contribute to a worsening of diabetic control. Thus, there is a double case for targeting HDLs in patients with type 2 diabetes: to reduce cardiovascular risk and also to improve glycemic control. Approaches to raising HDL levels include lifestyle factors such as weight reduction, increased physical activity and stopping smoking. There is an ongoing search for HDL-raising drugs as agents to use in patients with type 2 diabetes in whom the HDL level remains low despite lifestyle interventions.

  8. High-density lipoprotein endocytosis in endothelial cells

    Institute of Scientific and Technical Information of China (English)

    Stefanie; Fruhwürth; Margit; Pavelka; Robert; Bittman; Werner; J; Kovacs; Katharina; M; Walter; Clemens; Rhrl; Herbert; Stangl

    2013-01-01

    AIM: To describe the way stations of high-density lipoprotein(HDL) uptake and its lipid exchange in endothelial cells in vitro and in vivo. METHODS: A combination of fluorescence microscopy using novel fluorescent cholesterol surrogates and electron microscopy was used to analyze HDL endocytosis in great detail in primary human endothelial cells. Further, HDL uptake was quantified using radio-labeled HDL particles. To validate the in vitro findings mice were injected with fluorescently labeled HDL and particle uptake in the liver was analyzed using fluorescencemicroscopy. RESULTS: HDL uptake occurred via clathrin-coated pits, tubular endosomes and multivesicular bodies in human umbilical vein endothelial cells. During uptake and resecretion, HDL-derived cholesterol was exchanged at a faster rate than cholesteryl oleate, resembling the HDL particle pathway seen in hepatic cells. In addition, lysosomes were not involved in this process and thus HDL degradation was not detectable. In vivo, we found HDL mainly localized in mouse hepatic endothelial cells. HDL was not detected in parenchymal liver cells, indicating that lipid transfer from HDL to hepatocytes occurs primarily via scavenger receptor, class B, type Ⅰ mediated selective uptake without concomitant HDL endocytosis. CONCLUSION: HDL endocytosis occurs via clathrincoated pits, tubular endosomes and multivesicular bodies in human endothelial cells. Mouse endothelial cells showed a similar HDL uptake pattern in vivo indicating that the endothelium is one major site of HDL endocytosis and transcytosis.

  9. Crystallographic alignment of high-density gallium nitride nanowire arrays.

    Science.gov (United States)

    Kuykendall, Tevye; Pauzauskie, Peter J; Zhang, Yanfeng; Goldberger, Joshua; Sirbuly, Donald; Denlinger, Jonathan; Yang, Peidong

    2004-08-01

    Single-crystalline, one-dimensional semiconductor nanostructures are considered to be one of the critical building blocks for nanoscale optoelectronics. Elucidation of the vapour-liquid-solid growth mechanism has already enabled precise control over nanowire position and size, yet to date, no reports have demonstrated the ability to choose from different crystallographic growth directions of a nanowire array. Control over the nanowire growth direction is extremely desirable, in that anisotropic parameters such as thermal and electrical conductivity, index of refraction, piezoelectric polarization, and bandgap may be used to tune the physical properties of nanowires made from a given material. Here we demonstrate the use of metal-organic chemical vapour deposition (MOCVD) and appropriate substrate selection to control the crystallographic growth directions of high-density arrays of gallium nitride nanowires with distinct geometric and physical properties. Epitaxial growth of wurtzite gallium nitride on (100) gamma-LiAlO(2) and (111) MgO single-crystal substrates resulted in the selective growth of nanowires in the orthogonal [1\\[Evec]0] and [001] directions, exhibiting triangular and hexagonal cross-sections and drastically different optical emission. The MOCVD process is entirely compatible with the current GaN thin-film technology, which would lead to easy scale-up and device integration.

  10. Survival of charged rho condensation at high temperature and density

    CERN Document Server

    Liu, Hao; Huang, Mei

    2015-01-01

    The charged vector $\\rho$ mesons in the presence of external magnetic fields at finite temperature $T$ and chemical potential $\\mu$ have been investigated in the framework of the Nambu--Jona-Lasinio model. We compute the masses of charged $\\rho$ mesons numerically as a function of the magnetic field for different values of temperature and chemical potential. The self-energy of the $\\rho$ meson contains the quark-loop contribution, i.e. the leading order contribution in $1/N_c$ expansion. The charged $\\rho$ meson mass decreases with the magnetic field and drops to zero at a critical magnetic field $eB_c$, which means that the charged vector meson condensation, i.e. the electromagnetic superconductor can be induced above the critical magnetic field. Surprisingly, it is found that the charged $\\rho$ condensation can even survive at high temperature and density. At zero temperature, the critical magnetic field just increases slightly with the chemical potential, which indicates that the charged $\\rho$ condensatio...

  11. Low fasting low high-density lipoprotein and postprandial lipemia

    Directory of Open Access Journals (Sweden)

    Sorodila Konstandina

    2004-07-01

    Full Text Available Abstract Background Low levels of high density lipoprotein (HDL cholesterol and disturbed postprandial lipemia are associated with coronary heart disease. In the present study, we evaluated the variation of triglyceride (TG postprandially in respect to serum HDL cholesterol levels. Results Fifty two Greek men were divided into 2 main groups: a the low HDL group (HDL p = 0.002. The low HDL group had significantly higher TG at 4, 6 and 8 h postprandially compared to the controls (p = 0.006, p = 0.002, and p p = 0.017 compared to the matched-control group. ROC analysis showed that fasting TG ≥ 121 mg/dl have 100% sensitivity and 81% specificity for an abnormal TG response (auc = 0.962, p Conclusions The delayed TG clearance postprandially seems to result in low HDL cholesterol even in subjects with low fasting TG. The fasting TG > 121 mg/dl are predictable for abnormal response to fatty meal.

  12. High-density lipoprotein (HDL) metabolism and bone mass.

    Science.gov (United States)

    Papachristou, Nicholaos I; Blair, Harry C; Kypreos, Kyriakos E; Papachristou, Dionysios J

    2017-05-01

    It is well appreciated that high-density lipoprotein (HDL) and bone physiology and pathology are tightly linked. Studies, primarily in mouse models, have shown that dysfunctional and/or disturbed HDL can affect bone mass through many different ways. Specifically, reduced HDL levels have been associated with the development of an inflammatory microenvironment that affects the differentiation and function of osteoblasts. In addition, perturbation in metabolic pathways of HDL favors adipoblastic differentiation and restrains osteoblastic differentiation through, among others, the modification of specific bone-related chemokines and signaling cascades. Increased bone marrow adiposity also deteriorates bone osteoblastic function and thus bone synthesis, leading to reduced bone mass. In this review, we present the current knowledge and the future directions with regard to the HDL-bone mass connection. Unraveling the molecular phenomena that underline this connection will promote the deeper understanding of the pathophysiology of bone-related pathologies, such as osteoporosis or bone metastasis, and pave the way toward the development of novel and more effective therapies against these conditions. © 2017 Society for Endocrinology.

  13. Preface to Special Topic: High-Energy Density Laboratory Astrophysics

    Energy Technology Data Exchange (ETDEWEB)

    Glenzer, Siegfried H.; /SLAC

    2017-04-01

    In the 1990s, when the large inertial confinement fusion facilities in the United States became accessible for discovery-class research, physicists soon realized that the combination of these energetic drivers with precision plasmas diagnostics would allow the unprecedented experimental study of astrophysical problems. These facilities routinely produce states of matter in the high-energy density physics regime, i.e., pressures above a million atmospheres, 1011 J/m3, and employ a suite of temporally and spatially resolving imaging and scattering measurements that were originally developed to understand the behavior of inertial confinement fusion plasmas. These capabilities bring to the field of astrophysics critical experimental tests of simulations in relevant regimes that are far from the conditions that can otherwise be routinely produced on earth.5 These astrophysical motivated studies are now finding their way into the laboratory plasma community. Further, laboratory astrophysics helped to motivate the development of new precision experimental capabilities; the latest being the world-class Linac Coherent Light Source (LCLS) x-ray laser at the Matter in Extreme Conditions instrument at Stanford that is dedicated to fundamental research.

  14. Iatrogenic severe depression of high-density lipoprotein cholesterol.

    Science.gov (United States)

    Mymin, D; Dembinski, T; Friesen, M H

    2009-07-01

    The authors present 5 cases of paradoxical depression of high-density lipoprotein (HDL) cholesterol induced by fibrate drugs. In a 24-month review of all cases seen in one physician's practice at the Winnipeg Health Sciences Centre Lipid Clinic, 492 patients made a total of 1187 visits. Sixty-eight of them were given a fibrate drug (14%). Ten patients had HDL cholesterol levels that were less than 0.5 mmol/L (2%), and of these, 5 cases were due to exposure to fenofibrate (1%). These 5 cases comprised 7.4% of the 68 patients who were given any fibrate drug during that period. Mean levels were as follows: HDL cholesterol on fenofibrate 0.27, off fenofibrate 1.0 mmol/L and apo A1 on fenofibrate 0.41, off fenofibrate 1.17 g/L. A literature review revealed documented cases in 37 patients involving fibrates alone or in combination with other drugs known to cause decreased HDL cholesterol levels. In 13 patients, exposure was to fibrate therapy alone; in those exposed to combinations, the effect was clearly attributable to fibrates in 9; in 14, the nonfibrates (mostly rosiglitazone) were the attributable drugs; and in 1, it was impossible to tell. Thus, fibrate therapy should always be suspected as a cause of profoundly depressed HDL cholesterol.

  15. Properties of recycled high density polyethylene and coffee dregs composites

    Directory of Open Access Journals (Sweden)

    Sibele Piedade Cestari

    2013-01-01

    Full Text Available Composites of recycled high density polyethylene (HDPE-R and coffee dregs (COFD were elaborated. The blends were made at the proportions of 100-0, 90-10, 80-20, 70-30, 60-40, 50-50 and 40-60% polymer-filler ratio. The materials were evaluated through scanning electron microscopy (SEM, differential scanning calorimetry (DSC, thermogravimetry/derivative thermogravimetry (TGA, and compressive resistance test. The compounding was done using a two-stage co-kneader system extruder, and then cylindrical specimens were injection molded. All composites had a fine dispersion of the COFD into the polymeric matrix. The composites degraded in two steps. The first one was in a temperature lower than the neat HDPE, but higher than the average processing temperature of the polymer. The melting temperature and the degree of crystallinity of the composites resulted similar to the neat HDPE ones. The compressive moduli of the composites resulted similar to the neat polymer one. The results show that these composites have interesting properties as a building material.

  16. Improving Robotic Assembly of Planar High Energy Density Targets

    Science.gov (United States)

    Dudt, D.; Carlson, L.; Alexander, N.; Boehm, K.

    2016-10-01

    Increased quantities of planar assemblies for high energy density targets are needed with higher shot rates being implemented at facilities such as the National Ignition Facility and the Matter in Extreme Conditions station of the Linac Coherent Light Source. To meet this growing demand, robotics are used to reduce assembly time. This project studies how machine vision and force feedback systems can be used to improve the quantity and quality of planar target assemblies. Vision-guided robotics can identify and locate parts, reducing laborious manual loading of parts into precision pallets and associated teaching of locations. On-board automated inspection can measure part pickup offsets to correct part drop-off placement into target assemblies. Force feedback systems can detect pickup locations and apply consistent force to produce more uniform glue bond thickness, thus improving the performance of the targets. System designs and performance evaluations will be presented. Work supported in part by the US DOE under the Science Undergraduate Laboratory Internships Program (SULI) and ICF Target Fabrication DE-NA0001808.

  17. A system verification platform for high-density epiretinal prostheses.

    Science.gov (United States)

    Chen, Kuanfu; Lo, Yi-Kai; Yang, Zhi; Weiland, James D; Humayun, Mark S; Liu, Wentai

    2013-06-01

    Retinal prostheses have restored light perception to people worldwide who have poor or no vision as a consequence of retinal degeneration. To advance the quality of visual stimulation for retinal implant recipients, a higher number of stimulation channels is expected in the next generation retinal prostheses, which poses a great challenge to system design and verification. This paper presents a system verification platform dedicated to the development of retinal prostheses. The system includes primary processing, dual-band power and data telemetry, a high-density stimulator array, and two methods for output verification. End-to-end system validation and individual functional block characterization can be achieved with this platform through visual inspection and software analysis. Custom-built software running on the computers also provides a good way for testing new features before they are realized by the ICs. Real-time visual feedbacks through the video displays make it easy to monitor and debug the system. The characterization of the wireless telemetry and the demonstration of the visual display are reported in this paper using a 256-channel retinal prosthetic IC as an example.

  18. Liquid lithium for high power density fragmentation targets

    Science.gov (United States)

    Nolen, J. A.; Reed, C. B.; Hassanein, A.; Morrissey, D. J.; Ottarson, J. H.; Sherrill, B. M.

    2001-10-01

    Windowless liquid lithium targets for in-flight fragmentation or fission of high power heavy ion beams are being developed for the U.S. RIA project. With uranium beam power of 100 kW and a beam spot diameter of 1 mm the power density in the target is over 1 MW/cm3. Thermal analysis for this example indicates a very low peak temperature for the lithium when flowing at a linear velocity of 10 m/s. A vacuum test chamber is under construction at Argonne at an existing liquid lithium facility to demonstrate a 2 cm thick windowless target. As a first step towards using liquid lithium target technology at a nuclear physics fragmentation facility, a lower power target is being constructed for use at the NSCL. This target will use beryllium windows with flowing lithium. It is designed for beams between oxygen and calcium with beam power above 3 kW. The tapered beryllium windows are each 1 mm thick for the calcium beams and 7 mm thick for the oxygen beams. The lithium is 5 mm thick. This gives an overall target thickness ranging from about 1 g/cm2 to 3 g/cm2 which is adjusted by moving the target vertically. The designs of these targets and the status of the prototypes will be discussed.

  19. High density 3D printed microfluidic valves, pumps, and multiplexers.

    Science.gov (United States)

    Gong, Hua; Woolley, Adam T; Nordin, Gregory P

    2016-07-07

    In this paper we demonstrate that 3D printing with a digital light processor stereolithographic (DLP-SLA) 3D printer can be used to create high density microfluidic devices with active components such as valves and pumps. Leveraging our previous work on optical formulation of inexpensive resins (RSC Adv., 2015, 5, 106621), we demonstrate valves with only 10% of the volume of our original 3D printed valves (Biomicrofluidics, 2015, 9, 016501), which were already the smallest that have been reported. Moreover, we show that incorporation of a thermal initiator in the resin formulation along with a post-print bake can dramatically improve the durability of 3D printed valves up to 1 million actuations. Using two valves and a valve-like displacement chamber (DC), we also create compact 3D printed pumps. With 5-phase actuation and a 15 ms phase interval, we obtain pump flow rates as high as 40 μL min(-1). We also characterize maximum pump back pressure (i.e., maximum pressure the pump can work against), maximum flow rate (flow rate when there is zero back pressure), and flow rate as a function of the height of the pump outlet. We further demonstrate combining 5 valves and one DC to create a 3-to-2 multiplexer with integrated pump. In addition to serial multiplexing, we also show that the device can operate as a mixer. Importantly, we illustrate the rapid fabrication and test cycles that 3D printing makes possible by implementing a new multiplexer design to improve mixing, and fabricate and test it within one day.

  20. Experimental study of high density foods for the Space Operations Center

    Science.gov (United States)

    Ahmed, S. M.

    1981-01-01

    The experimental study of high density foods for the Space Operations Center is described. A sensory evaluation of the high density foods was conducted first to test the acceptability of the products. A shelf-life study of the high density foods was also conducted for three different time lengths at three different temperatures. The nutritional analysis of the high density foods is at present incomplete.

  1. High-Density Plasma Reactors: Simulations for Design

    Science.gov (United States)

    Hash, David B.; Meyyappan, Meyya; Arnold, James O. (Technical Monitor)

    1998-01-01

    The development of improved and more efficient plasma reactors is a costly process for the semiconductor industry. Until five years ago, the Industry made most of its advancements through a trial and error approach. More recently, the role of computational modeling in the design process has increased. Both conventional computational fluid dynamics (CFD) techniques like Navier-Stokes solvers as well as particle simulation methods are used to model plasma reactor flowfields. However, since high-density plasma reactors generally operate at low gas pressures on the order of 1 to 10 mTorr, a particle simulation may be necessary because of the failure of CFD techniques to model rarefaction effects. The direct simulation Monte Carlo method is the most widely accepted and employed particle simulation tool and has previously been used to investigate plasma reactor flowfields. A plasma DSMC code is currently under development at NASA Ames Research Center with its foundation as the object-oriented parallel Cornell DSMC code, MONACO. The present investigation is a follow up of a neutral flow investigation of the effects of process parameters as well as reactor design on etch rate and etch rate uniformity. The previous work concentrated on silicon etch of a chlorine flow in a configuration typical of electron cyclotron resonance (ECR) or helical resonator type reactors. The effects of the plasma on the dissociation chemistry were modeled by making assumptions about the electron temperature and number density. The electrons or ions themselves were not simulated.The present work extends these results by simulating the charged species.The electromagnetic fields are calculated such that power deposition is modeled self-consistently. Electron impact reactions are modeled along with mechanisms for charge exchange. An bipolar diffusion assumption is made whereby electrons remain tied to the ions. However, the velocities of tile electrons are allowed to be modified during collisions

  2. High-density cell systems incorporating polymer microspheres as microenvironmental regulators in engineered cartilage tissues.

    Science.gov (United States)

    Solorio, Loran D; Vieregge, Eran L; Dhami, Chirag D; Alsberg, Eben

    2013-06-01

    To address the significant clinical need for tissue-engineered therapies for the repair and regeneration of articular cartilage, many systems have recently been developed using bioactive polymer microspheres as regulators of the chondrogenic microenvironment within high-density cell cultures. In this review, we highlight various densely cellular systems utilizing polymer microspheres as three-dimensional (3D) structural elements within developing engineered cartilage tissue, carriers for cell expansion and delivery, vehicles for spatiotemporally controlled growth factor delivery, and directors of cell behavior via regulation of cell-biomaterial interactions. The diverse systems described herein represent a shift from the more traditional tissue engineering approach of combining cells and growth factors within a biomaterial scaffold, to the design of modular systems that rely on the assembly of cells and bioactive polymer microspheres as building blocks to guide the creation of articular cartilage. Cell-based assembly of 3D microsphere-incorporated structures represents a promising avenue for the future of tissue engineering.

  3. High thermal power density heat transfer apparatus providing electrical isolation at high temperature using heat pipes

    Science.gov (United States)

    Morris, J. F. (Inventor)

    1985-01-01

    This invention is directed to transferring heat from an extremely high temperature source to an electrically isolated lower temperature receiver. The invention is particularly concerned with supplying thermal power to a thermionic converter from a nuclear reactor with electric isolation. Heat from a high temperature heat pipe is transferred through a vacuum or a gap filled with electrically nonconducting gas to a cooler heat pipe. If the receiver requires gratr thermal power density, geometries are used with larger heat pipe areas for transmitting and receiving energy than the area for conducting the heat to the thermionic converter. In this way the heat pipe capability for increasing thermal power densities compensates for the comparative low thermal power densities through the electrically nonconducting gap between the two heat pipes.

  4. Generation of tunable, high repetition rate frequency combs with equalized spectra using carrier injection based silicon modulators

    Science.gov (United States)

    Nagarjun, K. P.; Selvaraja, Shankar Kumar; Supradeepa, V. R.

    2016-03-01

    High repetition-rate frequency combs with tunable repetition rate and carrier frequency are extensively used in areas like Optical communications, Microwave Photonics and Metrology. A common technique for their generation is strong phase modulation of a CW-laser. This is commonly implemented using Lithium-Niobate based modulators. With phase modulation alone, the combs have poor spectral flatness and significant number of missing lines. To overcome this, a complex cascade of multiple intensity and phase modulators are used. A comb generator on Silicon based on these principles is desirable to enable on-chip integration with other functionalities while reducing power consumption and footprint. In this work, we analyse frequency comb generation in carrier injection based Silicon modulators. We observe an interesting effect in these comb generators. Enhanced absorption accompanying carrier injection, an undesirable effect in data modulators, shapes the amplitude here to enable high quality combs from a single modulator. Thus, along with reduced power consumption to generate a specific number of lines, the complexity has also been significantly reduced. We use a drift-diffusion solver and mode solver (Silvaco TCAD) along with Soref-Bennett relations to calculate the variations in refractive indices and absorption of an optimized Silicon PIN - waveguide modulator driven by an unbiased high frequency (10 Ghz) voltage signal. Our simulations demonstrate that with a device length of 1 cm, a driving voltage of 2V and minor shaping with a passive ring-resonator filter, we obtain 37 lines with a flatness better than 5-dB across the band and power consumption an order of magnitude smaller than Lithium-Niobate modulators.

  5. Anisotropic charge carrier mobilities in bulk silicon at high electric fields

    CERN Document Server

    Becker, Julian; Klanner, Robert

    2010-01-01

    The mobility of electrons and holes in silicon depends on many parameters. Two of them are the electric field and the temperature. It has been observed previously that the mobility in the transition region between ohmic transport and saturation velocities is a function of the orientation of the crystal lattice. This paper presents a new set of parameters for the mobility as function of temperature and electric field for $$ and $$ crystal orientation. These parameters are derived from time of flight measurements of drifting charge carriers in planar p$^+$nn$^+$ diodes in the temperature range between -30$^\\circ$C and 50$^\\circ$C and electric fields of 2$\\times$10$^3$~V/cm to 2$\\times$10$^4$~V/cm.

  6. High-performance evanescently-coupled uni-traveling-carrier photodiodes

    Institute of Scientific and Technical Information of China (English)

    Zhang Yun-Xiao; Liao Zai-Yi; Wang Wei

    2009-01-01

    A new evanescently-coupled uni-traveling-carrier photodiode (EC-UTC PD) based on a multimode diluted waveguide (MDW) structure is fabricated, analysed and characterized. Optical and electrical characteristics of the device are investigated. The excellent characteristics are demonstrated such as a responsivity of 0.36 A/W, a bandwidth of 11.5 GHz and a small-signal 1-dB compression current greater than 18 mA at 10 GHz. The saturation current is significantly improved compared with those of similar evanescently-coupled pin photodiodes. The radio frequency (RF)bandwidth can be further improved by eliminating RF losses induced by the cables, the probe and the bias tee between the photodiode and the spectrum analyzer.

  7. Terahertz study of ultrafast carrier dynamics in InGaN/GaN multiple quantum wells

    Science.gov (United States)

    Porte, H. P.; Turchinovich, D.; Cooke, D. G.; Jepsen, P. Uhd

    2009-11-01

    Ultrafast carrier dynamics in InGaN/GaN multiple quantum wells is measured by time-resolved terahertz spectroscopy. The built-in piezoelectric field is initially screened by photoexcited, polarized carriers, and is gradullay restored as the carriers recombine. We observe a nonexponential decay of the carrier density. Time-integrated photoluminescence spectra have shown a complete screening of the built-in piezoelectric field at high excitation fluences. We also observe that the terahertz conductivity spectra differs from simple Drude conductivity, describing the response of free carriers, and are well fitted by the Drude-Smith model.

  8. Terahertz study of ultrafast carrier dynamics in InGaN/GaN multiple quantum wells

    Energy Technology Data Exchange (ETDEWEB)

    Porte, H P; Turchinovich, D; Cooke, D G; Jepsen, P Uhd, E-mail: hpor@fotonik.dtu.d [DTU Fotonik, Department of Photonics Engineering, Technical University of Denmark, Oersteds Plads 343, DK 2800 Kongens Lyngby (Denmark)

    2009-11-15

    Ultrafast carrier dynamics in InGaN/GaN multiple quantum wells is measured by time-resolved terahertz spectroscopy. The built-in piezoelectric field is initially screened by photoexcited, polarized carriers, and is gradullay restored as the carriers recombine. We observe a nonexponential decay of the carrier density. Time-integrated photoluminescence spectra have shown a complete screening of the built-in piezoelectric field at high excitation fluences. We also observe that the terahertz conductivity spectra differs from simple Drude conductivity, describing the response of free carriers, and are well fitted by the Drude-Smith model.

  9. A New Multilevel Converter Structure For High-Power Applications using Multi-carrier PWM Switching Strategy

    Directory of Open Access Journals (Sweden)

    Rasoul Shalchi Alishah

    2015-06-01

    Full Text Available In recent, several numbers of multilevel inverter structures have been introduced that the numbers of circuit devices have been reduced.  This paper introduces a new structure for multilevel inverter which can be used in high-power applications. The proposed topology is based on cascaded connection of basic units. This topology consists of minimum number of circuit components such as IGBT, gate driver circuit and antiparallel diode. For proposed topology, two methods are presented for determination of dc voltage sources values. Multi-carrier PWM method for 25-level proposed topology is used. Verification of the analytical results is done using MATLAB simulation.

  10. Analytical Estimation of Carrier Phase Recovery Approaches in Long-Haul High-Speed Optical Communication Systems

    CERN Document Server

    Xu, Tianhua

    2016-01-01

    The analytical study on the carrier phase estimation (CPE) approaches, involving a one-tap normalized least-mean-square (NLMS) algorithm, a block-wise average (BWA) algorithm, and a Viterbi-Viterbi (VV) algorithm has been investigated in the long-haul high-speed n-level phase shift keying (n-PSK) coherent optical fiber communication systems. The close-form predictions for the bit-error-rate (BER) performance have been derived and analyzed by considering both the intrinsic laser phase noise and the equalization enhanced phase noise (EEPN).

  11. Queuing Theory Based Co-Channel Interference Analysis Approach for High-Density Wireless Local Area Networks

    Science.gov (United States)

    Zhang, Jie; Han, Guangjie; Qian, Yujie

    2016-01-01

    Increased co-channel interference (CCI) in wireless local area networks (WLANs) is bringing serious resource constraints to today’s high-density wireless environments. CCI in IEEE 802.11-based networks is inevitable due to the nature of the carrier sensing mechanism however can be reduced by resource optimization approaches. That means the CCI analysis is basic, but also crucial for an efficient resource management. In this article, we present a novel CCI analysis approach based on the queuing theory, which considers the randomness of end users’ behavior and the irregularity and complexity of network traffic in high-density WLANs that adopts the M/M/c queuing model for CCI analysis. Most of the CCIs occur when multiple networks overlap and trigger channel contentions; therefore, we use the ratio of signal-overlapped areas to signal coverage as a probabilistic factor to the queuing model to analyze the CCI impacts in highly overlapped WLANs. With the queuing model, we perform simulations to see how the CCI influences the quality of service (QoS) in high-density WLANs. PMID:27563896

  12. Queuing Theory Based Co-Channel Interference Analysis Approach for High-Density Wireless Local Area Networks.

    Science.gov (United States)

    Zhang, Jie; Han, Guangjie; Qian, Yujie

    2016-08-23

    Increased co-channel interference (CCI) in wireless local area networks (WLANs) is bringing serious resource constraints to today's high-density wireless environments. CCI in IEEE 802.11-based networks is inevitable due to the nature of the carrier sensing mechanism however can be reduced by resource optimization approaches. That means the CCI analysis is basic, but also crucial for an efficient resource management. In this article, we present a novel CCI analysis approach based on the queuing theory, which considers the randomness of end users' behavior and the irregularity and complexity of network traffic in high-density WLANs that adopts the M/M/c queuing model for CCI analysis. Most of the CCIs occur when multiple networks overlap and trigger channel contentions; therefore, we use the ratio of signal-overlapped areas to signal coverage as a probabilistic factor to the queuing model to analyze the CCI impacts in highly overlapped WLANs. With the queuing model, we perform simulations to see how the CCI influences the quality of service (QoS) in high-density WLANs.

  13. Integration of high capacity materials into interdigitated mesostructured electrodes for high energy and high power density primary microbatteries

    Science.gov (United States)

    Pikul, James H.; Liu, Jinyun; Braun, Paul V.; King, William P.

    2016-05-01

    Microbatteries are increasingly important for powering electronic systems, however, the volumetric energy density of microbatteries lags behind that of conventional format batteries. This paper reports a primary microbattery with energy density 45.5 μWh cm-2 μm-1 and peak power 5300 μW cm-2 μm-1, enabled by the integration of large volume fractions of high capacity anode and cathode chemistry into porous micro-architectures. The interdigitated battery electrodes consist of a lithium metal anode and a mesoporous manganese oxide cathode. The key enabler of the high energy and power density is the integration of the high capacity manganese oxide conversion chemistry into a mesostructured high power interdigitated bicontinuous cathode architecture and an electrodeposited dense lithium metal anode. The resultant energy density is greater than previously reported three-dimensional microbatteries and is comparable to commercial conventional format lithium-based batteries.

  14. Chemically and Thermally Stable High Energy Density Silicone Composites Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Thermal energy storage systems with 300 ? 1000 kJ/kg energy density through either phase changes or chemical heat absorption are sought by NASA. This proposed effort...

  15. Feasibility of high-speed power line carrier system to Japanese overhead low voltage distribution lines; Teiatsu haidensen hanso no kosokuka no kanosei (hanso sningo denpa purogram no kanosei)

    Energy Technology Data Exchange (ETDEWEB)

    Suzuki, T.; Takeshita, K.; Ishino, R.

    2000-06-01

    The high-speed distribution line carrier systems on underground distribution lines are being developed in Germany. To estimate these systems on Japanese overhead low voltage distribution lines, the Carrier Propagation Program has been developed and applicability of OFDM system was roughly estimated. 1. Carrier Propagation Program Carrier Propagation Program that calculates the carrier propagation characteristics of any line structure was developed. 2. Carrier propagation characteristics Carrier propagation characteristics on typical Japanese overhead low voltage distribution lines were calculated 3.Rough estimation of OFDM system Electric fields caused by carrier at near point were calculated on the basis on carrier propagation characteristics. Results of rough estimation are as follows: - Electric field caused by carrier of more than 2Mbps system exceeds the value of the regulation. (author)

  16. High-energy side-peak emission of exciton-polariton condensates in high density regime.

    Science.gov (United States)

    Horikiri, Tomoyuki; Yamaguchi, Makoto; Kamide, Kenji; Matsuo, Yasuhiro; Byrnes, Tim; Ishida, Natsuko; Löffler, Andreas; Höfling, Sven; Shikano, Yutaka; Ogawa, Tetsuo; Forchel, Alfred; Yamamoto, Yoshihisa

    2016-05-19

    In a standard semiconductor laser, electrons and holes recombine via stimulated emission to emit coherent light, in a process that is far from thermal equilibrium. Exciton-polariton condensates-sharing the same basic device structure as a semiconductor laser, consisting of quantum wells coupled to a microcavity-have been investigated primarily at densities far below the Mott density for signatures of Bose-Einstein condensation. At high densities approaching the Mott density, exciton-polariton condensates are generally thought to revert to a standard semiconductor laser, with the loss of strong coupling. Here, we report the observation of a photoluminescence sideband at high densities that cannot be accounted for by conventional semiconductor lasing. This also differs from an upper-polariton peak by the observation of the excitation power dependence in the peak-energy separation. Our interpretation as a persistent coherent electron-hole-photon coupling captures several features of this sideband, although a complete understanding of the experimental data is lacking. A full understanding of the observations should lead to a development in non-equilibrium many-body physics.

  17. Transport analysis of high radiation and high density plasmas in the ASDEX Upgrade tokamak

    Directory of Open Access Journals (Sweden)

    Casali L.

    2014-01-01

    Full Text Available Future fusion reactors, foreseen in the “European road map” such as DEMO, will operate under more demanding conditions compared to present devices. They will require high divertor and core radiation by impurity seeding to reduce heat loads on divertor target plates. In addition, DEMO will have to work at high core densities to reach adequate fusion performance. The performance of fusion reactors depends on three essential parameters: temperature, density and energy confinement time. The latter characterizes the loss rate due to both radiation and transport processes. The DEMO foreseen scenarios described above were not investigated so far, but are now addressed at the ASDEX Upgrade tokamak. In this work we present the transport analysis of such scenarios. Plasma with high radiation by impurity seeding: transport analysis taking into account the radiation distribution shows no change in transport during impurity seeding. The observed confinement improvement is an effect of higher pedestal temperatures which extend to the core via stiffness. A non coronal radiation model was developed and compared to the bolometric measurements in order to provide a reliable radiation profile for transport calculations. High density plasmas with pellets: the analysis of kinetic profiles reveals a transient phase at the start of the pellet fuelling due to a slower density build up compared to the temperature decrease. The low particle diffusion can explain the confinement behaviour.

  18. How High Local Charge Carrier Mobility and an Energy Cascade in a Three-Phase Bulk Heterojunction Enable >90% Quantum Efficiency

    KAUST Repository

    Burke, Timothy M.

    2013-12-27

    Charge generation in champion organic solar cells is highly efficient in spite of low bulk charge-carrier mobilities and short geminate-pair lifetimes. In this work, kinetic Monte Carlo simulations are used to understand efficient charge generation in terms of experimentally measured high local charge-carrier mobilities and energy cascades due to molecular mixing. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Differential analysis for high density tiling microarray data

    Directory of Open Access Journals (Sweden)

    Kapranov Philipp

    2007-09-01

    Full Text Available Abstract Background High density oligonucleotide tiling arrays are an effective and powerful platform for conducting unbiased genome-wide studies. The ab initio probe selection method employed in tiling arrays is unbiased, and thus ensures consistent sampling across coding and non-coding regions of the genome. These arrays are being increasingly used to study the associated processes of transcription, transcription factor binding, chromatin structure and their association. Studies of differential expression and/or regulation provide critical insight into the mechanics of transcription and regulation that occurs during the developmental program of a cell. The time-course experiment, which comprises an in-vivo system and the proposed analyses, is used to determine if annotated and un-annotated portions of genome manifest coordinated differential response to the induced developmental program. Results We have proposed a novel approach, based on a piece-wise function – to analyze genome-wide differential response. This enables segmentation of the response based on protein-coding and non-coding regions; for genes the methodology also partitions differential response with a 5' versus 3' versus intra-genic bias. Conclusion The algorithm built upon the framework of Significance Analysis of Microarrays, uses a generalized logic to define regions/patterns of coordinated differential change. By not adhering to the gene-centric paradigm, discordant differential expression patterns between exons and introns have been identified at a FDR of less than 12 percent. A co-localization of differential binding between RNA Polymerase II and tetra-acetylated histone has been quantified at a p-value -13. The prototype R code has been made available as supplementary material [see Additional file 1]. Additional file 1 gsam_prototypercode.zip. File archive comprising of prototype R code for gSAM implementation including readme and examples. Click here for file

  20. Differential analysis for high density tiling microarray data.

    Science.gov (United States)

    Ghosh, Srinka; Hirsch, Heather A; Sekinger, Edward A; Kapranov, Philipp; Struhl, Kevin; Gingeras, Thomas R

    2007-09-24

    High density oligonucleotide tiling arrays are an effective and powerful platform for conducting unbiased genome-wide studies. The ab initio probe selection method employed in tiling arrays is unbiased, and thus ensures consistent sampling across coding and non-coding regions of the genome. These arrays are being increasingly used to study the associated processes of transcription, transcription factor binding, chromatin structure and their association. Studies of differential expression and/or regulation provide critical insight into the mechanics of transcription and regulation that occurs during the developmental program of a cell. The time-course experiment, which comprises an in-vivo system and the proposed analyses, is used to determine if annotated and un-annotated portions of genome manifest coordinated differential response to the induced developmental program. We have proposed a novel approach, based on a piece-wise function - to analyze genome-wide differential response. This enables segmentation of the response based on protein-coding and non-coding regions; for genes the methodology also partitions differential response with a 5' versus 3' versus intra-genic bias. The algorithm built upon the framework of Significance Analysis of Microarrays, uses a generalized logic to define regions/patterns of coordinated differential change. By not adhering to the gene-centric paradigm, discordant differential expression patterns between exons and introns have been identified at a FDR of less than 12 percent. A co-localization of differential binding between RNA Polymerase II and tetra-acetylated histone has been quantified at a p-value < 0.003; it is most significant at the 5' end of genes, at a p-value < 10-13. The prototype R code has been made available as supplementary material [see Additional file 1].

  1. Atlas Pulsed Power Facility for High Energy Density Physics Experiments

    Energy Technology Data Exchange (ETDEWEB)

    Miller, R.B.; Ballard, E.O.; Barr, G.W.; Bowman, D.W.; Chochrane, J.C.; Davis, H.A.; Elizondo, J.M.; Gribble, R.F.; Griego, J.R.; Hicks, R.D.; Hinckley, W.B.; Hosack, K.W.; Nielsen, K.E.; Parker, J.V.; Parsons, M.O.; Rickets, R.L.; Salazar, H.R.; Sanchez, P.G.; Scudder, D.W.; Shapiro, C.; Thompson, M.C.; Trainor, R.J.; Valdez, G.A.; Vigil, B.N.; Watt, R.G.; Wysock, F.J.

    1999-06-07

    The Atlas facility, now under construction at Los Alamos National Laboratory (LANL), will provide a unique capability for performing high-energy-density experiments in support of weapon-physics and basic-research programs. It is intended to be an international user facility, providing opportunities for researchers from national laboratories and academic institutions around the world. Emphasizing institutions around the world. Emphasizing hydrodynamic experiments, Atlas will provide the capability for achieving steady shock pressures exceeding 10-Mbar in a volume of several cubic centimeters. In addition, the kinetic energy associated with solid liner implosion velocities exceeding 12 km/s is sufficient to drive dense, hydrodynamic targets into the ionized regime, permitting the study of complex issues associated with strongly-coupled plasmas. The primary element of Atlas is a 23-MJ capacitor bank, comprised of 96 separate Marx generators housed in 12 separate oil-filled tanks, surrounding a central target chamber. Each tank will house two, independently-removable maintenance units, with each maintenance unit consisting of four Marx modules. Each Marx module has four capacitors that can each be charged to a maximum of 60 kilovolts. When railgap switches are triggered, the marx modules erect to a maximum of 240 kV. The parallel discharge of these 96 Marx modules will deliver a 30-MA current pulse with a 4-5-{micro}s risetime to a cylindrical, imploding liner via 24 vertical, tri-plate, oil-insulated transmission lines. An experimental program for testing and certifying all Marx and transmission line components has been completed. A complete maintenance module and its associated transmission line (the First Article) are now under construction and testing. The current Atlas schedule calls for construction of the machine to be complete by August, 2000. Acceptance testing is scheduled to begin in November, 2000, leading to initial operations in January, 2001.

  2. Surface interactions involved in flashover with high density electronegative gases.

    Energy Technology Data Exchange (ETDEWEB)

    Hodge, Keith Conquest; Warne, Larry Kevin; Jorgenson, Roy Eberhardt; Wallace, Zachariah Red; Lehr, Jane Marie

    2010-01-01

    This report examines the interactions involved with flashover along a surface in high density electronegative gases. The focus is on fast ionization processes rather than the later time ionic drift or thermalization of the discharge. A kinetic simulation of the gas and surface is used to examine electron multiplication and includes gas collision, excitation and ionization, and attachment processes, gas photoionization and surface photoemission processes, as well as surface attachment. These rates are then used in a 1.5D fluid ionization wave (streamer) model to study streamer propagation with and without the surface in air and in SF6. The 1.5D model therefore includes rates for all these processes. To get a better estimate for the behavior of the radius we have studied radial expansion of the streamer in air and in SF6. The focus of the modeling is on voltage and field level changes (with and without a surface) rather than secondary effects, such as, velocities or changes in discharge path. An experiment has been set up to carry out measurements of threshold voltages, streamer velocities, and other discharge characteristics. This setup includes both electrical and photographic diagnostics (streak and framing cameras). We have observed little change in critical field levels (where avalanche multiplication sets in) in the gas alone versus with the surface. Comparisons between model calculations and experimental measurements are in agreement with this. We have examined streamer sustaining fields (field which maintains ionization wave propagation) in the gas and on the surface. Agreement of the gas levels with available literature is good and agreement between experiment and calculation is good also. Model calculations do not indicate much difference between the gas alone versus the surface levels. Experiments have identified differences in velocity between streamers on the surface and in the gas alone (the surface values being larger).

  3. High-density lipoprotein and atherosclerosis: Roles of lipid transporters

    Institute of Scientific and Technical Information of China (English)

    Yoshinari; Uehara; Keijiro; Saku

    2014-01-01

    Various previous studies have found a negative cor-relation between the risk of cardiovascular events and serum high-density lipoprotein(HDL) cholesterol levels. The reverse cholesterol transport, a pathway of choles-terol from peripheral tissue to liver which has several potent antiatherogenic properties. For instance, the particles of HDL mediate to transport cholesterol from cells in arterial tissues, particularly from atherosclerotic plaques, to the liver. Both ATP-binding cassette trans-porters(ABC) A1 and ABCG1 are membrane cholesterol transporters and have been implicated in mediating cholesterol effluxes from cells in the presence of HDL and apolipoprotein A-I, a major protein constituent of HDL. Previous studies demonstrated that ABCA1 and ABCG1 or the interaction between ABCA1 and ABCG1 exerted antiatherosclerotic effects. As a therapeutic approach for increasing HDL cholesterol levels, much focus has been placed on increasing HDL cholesterol levels as well as enhancing HDL biochemical functions. HDL therapies that use injections of reconstituted HDL, apoA-I mimetics, or full-length apoA-I have shown dramatic effectiveness. In particular, a novel apoA-I mi-metic peptide, Fukuoka University ApoA-I Mimetic Pep-tide, effectively removes cholesterol via specific ABCA1 and other transporters, such as ABCG1, and has an an-tiatherosclerotic effect by enhancing the biological func-tions of HDL without changing circulating HDL choles-terol levels. Thus, HDL-targeting therapy has significant atheroprotective potential, as it uses lipid transporter-targeting agents, and may prove to be a therapeutic tool for atherosclerotic cardiovascular diseases.

  4. Self-sustained focusing of high-density streaming plasma

    Science.gov (United States)

    Bugaev, A.; Dobrovolskiy, A.; Goncharov, A.; Gushenets, V.; Litovko, I.; Naiko, I.; Oks, E.

    2017-01-01

    We describe our observations of the transport through an electrostatic plasma lens of a wide-aperture, high-current, low energy, metal-ion plasma flow produced by a cathodic arc discharge. The lens input aperture was 80 mm, the length of the lens was 140 mm, and there were three electrostatic ring electrodes located in a magnetic field formed by permanent magnets. The lens outer electrodes were grounded and the central electrode was biased up to -3 kV. The plasma was a copper plasma with directed (streaming) ion energy 20-40 eV, and the equivalent ion current was up to several amperes depending on the potential applied to the central lens electrode. We find that when the central lens electrode is electrically floating, the current density of the plasma flow at the lens focus increases by up to 40%-50%, a result that is in good agreement with a theoretical treatment based on plasma-optical principles of magnetic insulation of electrons and equipotentialization along magnetic field lines. When the central lens electrode is biased negatively, an on-axis stream of energetic electrons is formed, which can also provide a mechanism for focusing of the plasma flow. Optical emission spectra under these conditions show an increase in intensity of lines corresponding to both copper atoms and singly charged copper ions, indicating the presence of fast electrons within the lens volume. These energetic electrons, as well as accumulating on-axis and providing ion focusing, can also assist in reducing the microdroplet component in the dense, low-temperature, metal plasma.

  5. Study on the saturation characteristics of high-speed uni-traveling-carrier photodiodes based on field screening analysis

    Institute of Scientific and Technical Information of China (English)

    Tuo Shi; Bing Xiong; Changzheng Sun; Yi Luo

    2011-01-01

    A back-illuminated mesa-Structure InGaAs/InP charge-compensated uni-traveling-carrier (UTC) photodi-ode (PD) is fabricated, and its saturation characteristics are investigated. The responsivity of the 40-μm-diameter PD is as high as 0.83 A/W, and the direct current (DC) saturation current is up to 275 mA. The 1-dB compression point at the 3-dB cutoff frequency of 9 GHz is measured to be 100 mA, corresponding to an output radio frequency (RP) power of up to 20.1 dBm. According to the calculated electric field distributions in the depleted region under both DC and alternating current (AC) conditions, the saturation of the UTC-PD is caused by complete field screening at high optical injection levels.%@@ A back-illuminated mesa-structure InGaAs/InP charge-compensated uni-traveling-carrier(UTC) photodiode(PD) is fabricated,and its saturation characteristics are investigated.The responsivity of the 40-μmdiameter PD is as high as 0.83 A/W,and the direct current(DC) saturation current is up to 275 Ma.

  6. Compensated readout for high-density MOS-gated memristor crossbar array

    KAUST Repository

    Zidan, Mohammed A.

    2015-01-01

    Leakage current is one of the main challenges facing high-density MOS-gated memristor arrays. In this study, we show that leakage current ruins the memory readout process for high-density arrays, and analyze the tradeoff between the array density and its power consumption. We propose a novel readout technique and its underlying circuitry, which is able to compensate for the transistor leakage-current effect in the high-density gated memristor array.

  7. Studies of high power density, pico-second rise-time light-activated semiconductor switch. Final report, 1 September 1987-31 December 1988

    Energy Technology Data Exchange (ETDEWEB)

    Yu, P.L.

    1988-12-31

    The carrier dynamics of the diode which is related to its electrical power switching behaviors is investigated in this program. A model is developed where the carrier transport and Maxwell equations are incorporated and self-consistent electrical-field profiles, current density and carrier are obtained in the PIN diode. Both low- and high-level optical excitations as well as low and high applied bias situations can be described by this model. The transient behavior of the diode switch at different optical energy levels is now well understood, while conventional theory for photodiodes at low-level excitation and at low bias cannot be applied to cases for high-level excitation and high bias. As a circuit element, the rise time of the switch under these circumstances depends on the time the internal field is cancelled out by mobile carriers generated. The predicted input-energy dependence and the transmission line impedance dependence of the rise time compare well with experimental results. The model also suggests the experimental configuration for obtaining power in the GW range. Finally, a preliminary investigation is made on the effects of avalanche multiplication on the performance of the diode switch.

  8. Superfluid and normal fluid density in high- Tc superconductors

    Science.gov (United States)

    Tanner, D. B.; Liu, H. L.; Quijada, M. A.; Zibold, A. M.; Berger, H.; Kelley, R. J.; Onellion, M.; Chou, F. C.; Johnston, D. C.; Rice, J. P.; Ginsberg, D. M.; Markert, J. T.

    1998-01-01

    The electronic properties of the cuprate superconductors have been studied by measuring the reflectance over the frequency range from the far-infrared to the near-ultraviolet(roughly, 10 meV-5 eV). There is an interesting behavior in both the normal state and the superconducting state. In the normal state, there is the well-known non-Drude distribution of the doping-induced spectral weight. In the superconducting state, the spectral weight of the superconducting condensate correlates with Tc in a variety of materials. Remarkably, in optimally doped superconductors, only about 20% of the doping-induced carriers joins the superfluid; the rest of the spectral weight remains at finite frequencies.

  9. The viscosity and density of sour gas fluids at high temperatures and high pressures

    Energy Technology Data Exchange (ETDEWEB)

    Giri, B.R.; Marriott, R.A.; Blais, P.; Clark, P.D. [Alberta Sulphur Research Ltd., Calgary, AB (Canada); Calgary Univ., AB (Canada). Dept. of Chemistry

    2010-01-15

    This poster session discussed an experiment designed to measure the viscosity and density of sour gas fluids at high temperatures and pressures. An option for disposing acid gases while enhancing the production of oil and gas fields is the re-injection of gases rich in hydrogen sulphide/carbon dioxide (H{sub 2}S/CO{sub 2}) into reservoirs up to very high pressures, but issues with respect to corrosion, compression, pumping, and transport need addressing, and the reliable high-density/high-pressure data needed to arrive at an optimum process concept and the design of pumps, compressors, and transport lines had up to this point been lacking. The experimental set up involved the use of a Vibrating Tube Densimeter and a Cambridge Viscometer. Working with toxic gases at very high pressures and obtaining highly accurate data in a wide range of conditions were two of the challenges faced during the experiment. The experiment resulted in physical property measurement systems being recalibrated and a new daily calibration routine being adopted for accuracy. The densities and viscosities of pure CO{sub 2} and sulphur dioxide (SO{sub 2}) in a wide pressure and temperature range were determined. 1 tab., 9 figs.

  10. Two-dimensional double-quantum spectroscopy: peak shapes as a sensitive probe of carrier interactions in quantum wells

    CERN Document Server

    Tollerud, Jonathan O

    2016-01-01

    We identify carrier scattering at densities below which it has previously been observed in semiconductor quantum wells. These effects are evident in the peakshapes of 2D double-quantum spectra, which change as a function of excitation density. At high excitation densities ($\\geq 10^{9}$ carriers/,cm$^{-2}$) we observe untilted peaks similar to those reported in previous experiments. At low excitation densities (<$10^{8}$ carriers cm$^{-2}$) we observe narrower, tilted peaks. Using a simple simulation, we show that tilted peak-shapes are expected in double-quantum spectra when inhomogeneous broadening is much larger than homogeneous broadening, and that fast pure-decoherence of the double-quantum coherence can obscure this peak tilt. These results show that carrier interactions are important at lower densities than previously expected, and that the `natural' double-quantum peakshapes are hidden by carrier interactions at the excitation densities typically used. Furthermore, these results demonstrate that an...

  11. High Current, High Density Arc Plasma as a New Source for WiPAL

    Science.gov (United States)

    Waleffe, Roger; Endrizzi, Doug; Myers, Rachel; Wallace, John; Clark, Mike; Forest, Cary; WiPAL Team

    2016-10-01

    The Wisconsin Plasma Astrophysics Lab (WiPAL) has installed a new array of nineteen plasma sources (plasma guns) on its 3 m diameter, spherical vacuum vessel. Each gun is a cylindrical, molybdenum, washer-stabilized, arc plasma source. During discharge, the guns are maintained at 1.2 kA across 100 V for 10 ms by the gun power supply establishing a high density plasma. Each plasma source is fired independently allowing for adjustable plasma parameters, with densities varying between 1018 -1019 m-3 and electron temperatures of 5-15 eV. Measurements were characterized using a 16 tip Langmuir probe. The plasma source will be used as a background plasma for the magnetized coaxial plasma gun (MCPG), the Terrestrial Reconnection Experiment (TREX), and as the plasma source for a magnetic mirror experiment. Temperature, density, and confinement results will be presented. This work is supported by the DoE and the NSF.

  12. Particle control in high power, high density long pulses on Tore Supra

    Energy Technology Data Exchange (ETDEWEB)

    Bucalossi, J.; Brosset, C.; Dufour, E.; Loarer, T.; Pegourie, B.; Tsitrone, E.; Basiuk, V.; Bremond, S.; Chantant, M.; Colas, L.; Commaux, N.; Geraud, A.; Grosman, A.; Guirlet, R.; Gunn, J.; Hertout, P.; Hoang, G.T.; Kazarian, F.; Mazon, D.; Maget, P.; Mitteau, R.; Monier-Garbet, P.; Moreau, P.; Saint-Laurent, F.; Schunke, B.; Vallet, J.C

    2005-07-01

    The plasma density and impurity level (Z(eff) {approx} 2) are perfectly controlled all along the 6 minute long discharges, the main limitation coming from the LH (lower hybrid) power source. After 60 s, the particle injection rate and the particle exhaust rate are constant. Therefore the retention rate, defined as the difference between these 2 quantities, is also constant at about 3.10{sup 20} D/s. These discharges were performed at low density and with LHCD (lower hybrid current drive). A new scenario has been recently developed combining ICRH (ion cyclotron resonance heating) and LHCD up to a total power of 10 MW at higher density and limited in time to 60 s by the capability of the ICRH heating systems. The infrared imaging protection system reveals lots of hot spots on the plasma facing components. These localized heat loads are attributed mainly to the fast particles which are accelerated in the near field generated by the IC and LH launchers. The gas injection rate necessary to maintain the plasma density in the high power high density scenarios (LHCD + ICRH) is substantially increased (up to a factor 3). Particle balance analysis based on pressure measurements shows that the absolute in-vessel retention rate, computed after 30 s of plasma is roughly equivalent in both scenarios (3.10{sup 20} D/s), whatever the ICRH power (from 0 to 4 MW) and the line integrated plasma density (from 2.5 to 4.10{sup 19} m{sup -2}) are. This result could indicate that the retention mechanisms could be dominated by wall processes such as diffusion in carbon porosities rather than plasma processes such as co-deposition, dependent on edge conditions. (A.C.)

  13. Study of high mobility carriers in Ni-doped CdO films

    Indian Academy of Sciences (India)

    A A Dakhel

    2013-10-01

    Cadmium oxide (CdO) doped with different amounts of nickel ion thin films have been prepared on silicon and glass substrates by vacuum evaporation technique. The effects of nickel doping on the structural, electrical, optical and optoelectronic properties of the host CdO films were systematically studied. The sample elemental composition was determined by the X-ray fluorescence spectroscopy method. The X-ray diffraction method was used to study the crystalline structure of the samples. It shows that some of Ni3+ ions occupy mainly locations when in interstitial positions and Cd2+-ion vacancies of CdO lattice. The bandgap of Ni-doped CdO suffers narrowing till 10–12% compared to undoped CdO. Such bandgap narrowing was studied within the framework of the available models. The electrical behaviours show that all the prepared Ni-doped CdO films are degenerate semiconductors. However, the nickel doping influences all the optoelectrical properties of CdO. Their d.c. conductivity, carrier concentration and mobility increased compared to undoped CdO film. The largest mobility of 112.6 cm2/V.s was measured for 1–2% Ni-doped CdO film. From optoelectronics point of view, Ni-doped CdO can be used in infrared-transparent-conducting-oxide (NIR–TCO) applications.

  14. Ultra-high cell-density silicon photomultipliers with high detection efficiency

    Science.gov (United States)

    Acerbi, Fabio; Gola, Alberto; Regazzoni, Veronica; Paternoster, Giovanni; Borghi, Giacomo; Piemonte, Claudio; Zorzi, Nicola

    2017-05-01

    Silicon photomultipliers (SiPMs) are arrays of many single-photon avalanche diodes (SPADs), all connected in parallel. Each SPAD is sensitive to single photons and the SiPM gives an output proportional to the number of detected photons. These sensors are becoming more and more popular in different applications, from high-energy physics to spectroscopy, and they have been significantly improved over last years, decreasing the noise, increasing the cell fill-factor (FF) and thus achieving very high photon-detection efficiency (PDE). In FBK (Trento, Italy), we developed new SiPM technologies with high-density (HD) and, more recently, ultra-high-density (UHD) of cells (i.e. density of SPADs). These technologies employ deep-trenches between cells, for electrical and optical isolation. As an extreme case the smallest-cell, SiPM, i.e. with 5μm cell pitch, has about 40000 SPADs per squared millimeter. Such small SPAD dimensions gives a significantly high dynamic range to the SiPM. These small-cells SiPM have a lower correlated noise (including lower afterpulsing probability) and a faster recharge time (in the order of few nanoseconds), and they also preserve a very good detection efficiency (despite the small SPAD dimension).

  15. High energy-density liquid rocket fuel performance

    Science.gov (United States)

    Rapp, Douglas C.

    1990-01-01

    A fuel performance database of liquid hydrocarbons and aluminum-hydrocarbon fuels was compiled using engine parametrics from the Space Transportation Engine Program as a baseline. Propellant performance parameters are introduced. General hydrocarbon fuel performance trends are discussed with respect to hydrogen-to-carbon ratio and heat of formation. Aluminum-hydrocarbon fuel performance is discussed with respect to aluminum metal loading. Hydrocarbon and aluminum-hydrocarbon fuel performance is presented with respect to fuel density, specific impulse and propellant density specific impulse.

  16. Current-voltage curve of a bipolar membrane at high current density

    NARCIS (Netherlands)

    Aritomi, T.; Boomgaard, van den Th.; Strathmann, H.

    1996-01-01

    The potential drop across a bipolar membrane was measured as a function of the applied current density. As a result, an inflection point was observed in the obtained current-voltage curve at high current density. This inflection point indicates that at high current densities water supply from outsid

  17. Current-voltage curve of a bipolar membrane at high current density

    NARCIS (Netherlands)

    Aritomi, T.; van den Boomgaard, Anthonie; Strathmann, H.

    1996-01-01

    The potential drop across a bipolar membrane was measured as a function of the applied current density. As a result, an inflection point was observed in the obtained current-voltage curve at high current density. This inflection point indicates that at high current densities water supply from

  18. OXIDATION OF DRY HYDROCARBONS AT HIGH-POWER DENSITY ANODES

    Energy Technology Data Exchange (ETDEWEB)

    K.Krist; O. Spaldon-Stewart; R. Remick

    2004-03-01

    This work builds upon discoveries by the University of Pennsylvania and others pertaining to the oxidation of dry hydrocarbon fuels in high temperature solid oxide fuel cells. The work reported here was restricted primarily to dry methane and confirms that YSZ-based cells, having ceria in the anode as a catalyst and copper in the anode as a current collector, can operate on dry methane for extended periods. Thirty-three lab-scale cells of various designs were fabricated and operated under a variety of conditions. The longest-lived cell gave stable performance on dry methane at 800 C for over 305 hours. Only slight carbon deposition was noted at the completion of the test. A corresponding nickel/YSZ-based anode would have lasted for less than an hour under these test conditions (which included open circuit potential measurements) before carbon fouling essentially destroyed the cell. The best performing cell achieved 112 mW/cm{sub 2} on dry methane at 800 C. Several problems were encountered with carbon fouling and declining open circuit voltages in many of the test cells after switching from operation on hydrogen to dry methane. Although not rigorously confirmed by experimentation, the results suggested that air infiltration through less than perfect perimeter seals or pinholes in the electrolytes, or both gave rise to conditions that caused the carbon fouling and OCV decline. Small amounts of air reacting with methane in a partial oxidation reaction could produce carbon monoxide that, in turn, would deposit the carbon. If this mechanism is confirmed, it implies that near perfect hardware is required for extended operation. Some evidence was also found for the formation of electrical shorts, probably from carbon deposits bridging the electrolyte. Work with odorized methane and with methane containing 100-ppm hydrogen sulfide confirmed that copper is stable at 800 C in dry hydrocarbon fuels in the presence of sulfur. In a number of cases, but not exclusively, the

  19. Biofuels Barrier Properties of Polyamide 6 and High Density Polyethylene

    Directory of Open Access Journals (Sweden)

    Fillot L.-A.

    2015-02-01

    Full Text Available In this paper, a comparison of the biofuels barrier properties of PolyAmide 6 (PA6 and High Density PolyEthylene (HDPE is presented. Model fuels were prepared as mixtures of toluene, isooctane and ethanol, the ethanol volume fraction varying between 0% and 100%. Barrier properties were determined at 40°C by gravimetric techniques or gas chromatography measurements, and it was shown that polyamide 6 permeability is lower than that of polyethylene on a wide range of ethanol contents up to 85% of ethanol (E85 in the biofuel, permeability of PA6 being 100 times lower than that of HDPE for low ethanol content fuels (E5, E0. The time-lags were also compared, and on the whole range of ethanol contents, HDPE permeation kinetics appears to be much faster than that of PA6, the time lag for a 1 mm thick specimens in presence of E10 being 50 days for PA6 and 0.5 days for HDPE. The compositions of the solvent fluxes were analyzed by FID gas chromatography, and it turned out that the solvent flux was mainly made up of ethanol (minimum 95% in the case of PA6, whereas in the case of HDPE, solvent flux was mainly made up of hydrocarbons. The implication of this difference in the solvent flux composition is discussed in the present article, and a side effect called the “fuel exhaustion process” is presented. The influence of the sample thickness was then studied, and for the different biofuels compositions, the pervaporation kinetics of polyamide 6 appeared to evolve with the square of the thickness, a long transitory regime being highlighted in the case of PA6. This result implies that the time needed to characterize the steady state permeability of thick PA6 parts such as fuel tanks can be very long (one year or more, this duration being far superior to the Euros 5 or Euro 6 standard emission measurements time scale. The influence of temperature on the permeability was finally assessed, and the activation energy that is the signature of the temperature

  20. Human endothelial progenitor cells internalize high-density lipoprotein.

    Science.gov (United States)

    Srisen, Kaemisa; Röhrl, Clemens; Meisslitzer-Ruppitsch, Claudia; Ranftler, Carmen; Ellinger, Adolf; Pavelka, Margit; Neumüller, Josef

    2013-01-01

    Endothelial progenitor cells (EPCs) originate either directly from hematopoietic stem cells or from a subpopulation of monocytes. Controversial views about intracellular lipid traffic prompted us to analyze the uptake of human high density lipoprotein (HDL), and HDL-cholesterol in human monocytic EPCs. Fluorescence and electron microscopy were used to investigate distribution and intracellular trafficking of HDL and its associated cholesterol using fluorescent surrogates (bodipy-cholesterol and bodipy-cholesteryl oleate), cytochemical labels and fluorochromes including horseradish peroxidase and Alexa Fluor® 568. Uptake and intracellular transport of HDL were demonstrated after internalization periods from 0.5 to 4 hours. In case of HDL-Alexa Fluor® 568, bodipy-cholesterol and bodipy-cholesteryl oleate, a photooxidation method was carried out. HDL-specific reaction products were present in invaginations of the plasma membrane at each time of treatment within endocytic vesicles, in multivesicular bodies and at longer periods of uptake, also in lysosomes. Some HDL-positive endosomes were arranged in form of "strings of pearl"- like structures. HDL-positive multivesicular bodies exhibited intensive staining of limiting and vesicular membranes. Multivesicular bodies of HDL-Alexa Fluor® 568-treated EPCs showed multilamellar intra-vacuolar membranes. At all periods of treatment, labeled endocytic vesicles and organelles were apparent close to the cell surface and in perinuclear areas around the Golgi apparatus. No HDL-related particles could be demonstrated close to its cisterns. Electron tomographic reconstructions showed an accumulation of HDL-containing endosomes close to the trans-Golgi-network. HDL-derived bodipy-cholesterol was localized in endosomal vesicles, multivesicular bodies, lysosomes and in many of the stacked Golgi cisternae and the trans-Golgi-network Internalized HDL-derived bodipy-cholesteryl oleate was channeled into the lysosomal intraellular

  1. Human endothelial progenitor cells internalize high-density lipoprotein.

    Directory of Open Access Journals (Sweden)

    Kaemisa Srisen

    Full Text Available Endothelial progenitor cells (EPCs originate either directly from hematopoietic stem cells or from a subpopulation of monocytes. Controversial views about intracellular lipid traffic prompted us to analyze the uptake of human high density lipoprotein (HDL, and HDL-cholesterol in human monocytic EPCs. Fluorescence and electron microscopy were used to investigate distribution and intracellular trafficking of HDL and its associated cholesterol using fluorescent surrogates (bodipy-cholesterol and bodipy-cholesteryl oleate, cytochemical labels and fluorochromes including horseradish peroxidase and Alexa Fluor® 568. Uptake and intracellular transport of HDL were demonstrated after internalization periods from 0.5 to 4 hours. In case of HDL-Alexa Fluor® 568, bodipy-cholesterol and bodipy-cholesteryl oleate, a photooxidation method was carried out. HDL-specific reaction products were present in invaginations of the plasma membrane at each time of treatment within endocytic vesicles, in multivesicular bodies and at longer periods of uptake, also in lysosomes. Some HDL-positive endosomes were arranged in form of "strings of pearl"- like structures. HDL-positive multivesicular bodies exhibited intensive staining of limiting and vesicular membranes. Multivesicular bodies of HDL-Alexa Fluor® 568-treated EPCs showed multilamellar intra-vacuolar membranes. At all periods of treatment, labeled endocytic vesicles and organelles were apparent close to the cell surface and in perinuclear areas around the Golgi apparatus. No HDL-related particles could be demonstrated close to its cisterns. Electron tomographic reconstructions showed an accumulation of HDL-containing endosomes close to the trans-Golgi-network. HDL-derived bodipy-cholesterol was localized in endosomal vesicles, multivesicular bodies, lysosomes and in many of the stacked Golgi cisternae and the trans-Golgi-network Internalized HDL-derived bodipy-cholesteryl oleate was channeled into the lysosomal

  2. Test of high density UC targets development at Gatchina for neutron rich radioactive beam facilities

    CERN Document Server

    Lhersonneau, G; Lanchais, A; Rizzi, V; Tecchio, L.B; Bajeat, O; Essabaa, S; Lau, C; Cheikh Mhamed, M; Roussière, B; Barzakh, A.E; Fedorov, D.V; lonan, A.M; lvanov, V.S; Mezilev, K.A; Moroz, F.V; Orlov, S.YU; Panteleevc, V.N; Volkovc, YU.M; Dubois, M; Eléon, C; Gaubert, G; Jardin, P; Leroy, R; Saint Laurent, M.G; Villari, A.C.C; Stroe, L; 10.1016/j.nimb.2008.05.033

    2008-01-01

    Production of on-line mass separator neutron rich isotopes using fission induced by 1 GeV protons on high density uranium carbide has been investigate and results compared with the low density targets yields.

  3. Stability Of Rubble Mound Breakwaters Using High Density Rock

    DEFF Research Database (Denmark)

    Burcharth, H. F.; Beck, J. B.

    2000-01-01

    The present paper discusses the effect of mass density on stability of rubble mound breakwaters. A short literature review of existing knowledge is give to establish a background for the ongoing research. Furthermore, several model tests are described in which the stability of rubble mound breakw...

  4. Formation of Los Angeles's low density and high car dependence

    Institute of Scientific and Technical Information of China (English)

    DAI Te-qi; JIN Feng-jun

    2009-01-01

    As a typical car-dependent city, Los Angeles (LA) is extensively used as an example in research to illustrate car influences on city form. Focusing on the features of LA's geologic conditions and civil circumstances, we argued that the relationship between LA's low-density pattern and car dependence is more involved than previously deemed simple causality. The low density should be primarily credited to the spacious requirement of the mining industry, frequent earthquakes and multiethnic population of the city. Oil reserves in LA fueled its economic boom and fast urbanization that coincided with the start of mass production of cheap cars, and cars became medium-priced consumables for average families. Politicians preference for short construction-peried projects enabled fast establishment of LA's highway infrastructure. The popularity of car use in return faciliatated further development of the low-density pattern of the city. The low-density urban form and car dependence created environmental and social problems for LA. Looking at P. R. China's motorization and urban development, we found that the trajectory of Beijing's motorization between 1978 and 2003 coincides with that of the U.S. in the 1910s and 1920s. Lessons from LA's urban and transportation development should be suggestive to China's urban and transportation planning.

  5. Patterned magnetic thin films for ultra high density recording

    NARCIS (Netherlands)

    Lodder, J.C.; Haast, M.A.M.; Abelmann, L.; Hadjipanayis, G.C.

    2001-01-01

    The areal bit density of magnetic disk recording has increased since 1990 60% per year and even in the last years 100%. Extrapolation of these rates leads to recording parameters not likely to be achieved without changes in the present way of storing hard disk data. One of the possible solutions is

  6. Short minority carrier lifetimes in highly nitrogen-doped 4H-SiC epilayers for suppression of the stacking fault formation in PiN diodes

    Science.gov (United States)

    Tawara, T.; Miyazawa, T.; Ryo, M.; Miyazato, M.; Fujimoto, T.; Takenaka, K.; Matsunaga, S.; Miyajima, M.; Otsuki, A.; Yonezawa, Y.; Kato, T.; Okumura, H.; Kimoto, T.; Tsuchida, H.

    2016-09-01

    We investigated the dependency of minority carrier lifetimes on the nitrogen concentration, temperature, and the injected carrier concentration for highly nitrogen-doped 4H-SiC epilayers. The minority carrier lifetimes greatly shortened when the nitrogen concentration exceeded 1018 cm-3 through enhancing direct band-to-band and Auger recombination and showed a slight variation in the temperature range from room temperature (RT) to 250 °C. The epilayer with a nitrogen concentration of 9.3 × 1018 cm-3 exhibited a very short minority carrier lifetime of 38 ns at RT and 43 ns at 250 °C. The short minority carrier lifetimes of the highly nitrogen-doped epilayer were confirmed to maintain the values even after the subsequent annealing of 1700 °C. 4H-SiC PiN diodes were fabricated by depositing a highly nitrogen-doped epilayer as a "recombination enhancing layer" between an n- drift layer free from basal plane dislocations and the substrate. The PiN diodes showed no formation of stacking faults and no increase in forward voltage during current conduction of 600 A/cm2 (DC), demonstrating that a highly nitrogen-doped buffer layer with a short minority carrier lifetime successfully suppresses the "bipolar degradation" phenomenon.

  7. ADX: a high field, high power density, Advanced Divertor test eXperiment

    Science.gov (United States)

    Vieira, R.; Labombard, B.; Marmar, E.; Irby, J.; Shiraiwa, S.; Terry, J.; Wallace, G.; Whyte, D. G.; Wolfe, S.; Wukitch, S.; ADX Team

    2014-10-01

    The MIT PSFC and collaborators are proposing an advanced divertor experiment (ADX) - a tokamak specifically designed to address critical gaps in the world fusion research program on the pathway to FNSF/DEMO. This high field (6.5 tesla, 1.5 MA), high power density (P/S ~ 1.5 MW/m2) facility would utilize Alcator magnet technology to test innovative divertor concepts for next-step DT fusion devices (FNSF, DEMO) at reactor-level boundary plasma pressures and parallel heat flux densities while producing high performance core plasma conditions. The experimental platform would also test advanced lower hybrid current drive (LHCD) and ion-cyclotron range of frequency (ICRF) actuators and wave physics at the plasma densities and magnetic field strengths of a DEMO, with the unique ability to deploy launcher structures both on the low-magnetic-field side and the high-field side - a location where energetic plasma-material interactions can be controlled and wave physics is most favorable for efficient current drive, heating and flow drive. This innovative experiment would perform plasma science and technology R&D necessary to inform the conceptual development and accelerate the readiness-for-deployment of FNSF/DEMO - in a timely manner, on a cost-effective research platform. Supported by DE-FC02-99ER54512.

  8. Guiding and collimating the fast electrons by using a low-density-core target with buried high density layers

    Science.gov (United States)

    Lv, Chong; Wan, Feng; Hou, Ya-Juan; Jia, Mo-Ran; Sang, Hai-Bo; Xie, Bai-Song; Liu, Shi-Bing

    2017-02-01

    A low-density-core target with buried high density layers is proposed to improve the transport of fast electrons and involved problems are investigated by using two-dimensional particle-in-cell simulations. It is demonstrated that this target can collimate the fast electrons efficiently and lead to a better beam quality. The enhancement is attributed to the weakening of the two stream instability and the better collimation by the self-generated multilayer megagauss magnetic field as well as the baroclinic magnetic field. Comparing this to that without buried high density layers, the energy flux of fast electrons is increased by a factor of about 1.8 and has a narrower transverse distribution in space. Besides, the dependence of the efficiency on the target parameters is examined, and the optimal target parameters are also obtained. Such a target can be useful to many applications, such as fast ignition in inertial fusion.

  9. Advanced and flexible multi-carrier receiver architecture for high-count multi-core fiber based space division multiplexed applications

    Science.gov (United States)

    Asif, Rameez

    2016-06-01

    Space division multiplexing (SDM), incorporating multi-core fibers (MCFs), has been demonstrated for effectively maximizing the data capacity in an impending capacity crunch. To achieve high spectral-density through multi-carrier encoding while simultaneously maintaining transmission reach, benefits from inter-core crosstalk (XT) and non-linear compensation must be utilized. In this report, we propose a proof-of-concept unified receiver architecture that jointly compensates optical Kerr effects, intra- and inter-core XT in MCFs. The architecture is analysed in multi-channel 512 Gbit/s dual-carrier DP-16QAM system over 800 km 19-core MCF to validate the digital compensation of inter-core XT. Through this architecture: (a) we efficiently compensates the inter-core XT improving Q-factor by 4.82 dB and (b) achieve a momentous gain in transmission reach, increasing the maximum achievable distance from 480 km to 1208 km, via analytical analysis. Simulation results confirm that inter-core XT distortions are more relentless for cores fabricated around the central axis of cladding. Predominantly, XT induced Q-penalty can be suppressed to be less than 1 dB up-to ‑11.56 dB of inter-core XT over 800 km MCF, offering flexibility to fabricate dense core structures with same cladding diameter. Moreover, this report outlines the relationship between core pitch and forward-error correction (FEC).

  10. N-Linked Glycans Are Assembled on Highly Reduced Dolichol Phosphate Carriers in the Hyperthermophilic Archaea Pyrococcus furiosus.

    Science.gov (United States)

    Chang, Michelle M; Imperiali, Barbara; Eichler, Jerry; Guan, Ziqiang

    2015-01-01

    In all three domains of life, N-glycosylation begins with the assembly of glycans on phosphorylated polyisoprenoid carriers. Like eukaryotes, archaea also utilize phosphorylated dolichol for this role, yet whereas the assembled oligosaccharide is transferred to target proteins from dolichol pyrophosphate in eukaryotes, archaeal N-linked glycans characterized to date are derived from a dolichol monophosphate carrier, apart from a single example. In this study, glycan-charged dolichol phosphate from the hyperthermophile Pyrococcus furiosus was identified and structurally characterized. Normal and reverse phase liquid chromatography-electrospray ionization mass spectrometry revealed the existence of dolichol phosphate charged with the heptasaccharide recently described in in vitro studies of N-glycosylation on this species. As with other described archaeal dolichol phosphates, the α- and ω-terminal isoprene subunits of the P. furiosus lipid are saturated, in contrast to eukaryal phosphodolichols that present only a saturated α-position isoprene subunit. Interestingly, an additional 1-4 of the 12-14 isoprene subunits comprising P. furiosus dolichol phosphate are saturated, making this lipid not only the longest archaeal dolichol phosphate described to date but also the most highly saturated.

  11. N-Linked Glycans Are Assembled on Highly Reduced Dolichol Phosphate Carriers in the Hyperthermophilic Archaea Pyrococcus furiosus.

    Directory of Open Access Journals (Sweden)

    Michelle M Chang

    Full Text Available In all three domains of life, N-glycosylation begins with the assembly of glycans on phosphorylated polyisoprenoid carriers. Like eukaryotes, archaea also utilize phosphorylated dolichol for this role, yet whereas the assembled oligosaccharide is transferred to target proteins from dolichol pyrophosphate in eukaryotes, archaeal N-linked glycans characterized to date are derived from a dolichol monophosphate carrier, apart from a single example. In this study, glycan-charged dolichol phosphate from the hyperthermophile Pyrococcus furiosus was identified and structurally characterized. Normal and reverse phase liquid chromatography-electrospray ionization mass spectrometry revealed the existence of dolichol phosphate charged with the heptasaccharide recently described in in vitro studies of N-glycosylation on this species. As with other described archaeal dolichol phosphates, the α- and ω-terminal isoprene subunits of the P. furiosus lipid are saturated, in contrast to eukaryal phosphodolichols that present only a saturated α-position isoprene subunit. Interestingly, an additional 1-4 of the 12-14 isoprene subunits comprising P. furiosus dolichol phosphate are saturated, making this lipid not only the longest archaeal dolichol phosphate described to date but also the most highly saturated.

  12. Achieving high carrier mobility exceeding 70 cm2/Vs in amorphous zinc tin oxide thin-film transistors

    Science.gov (United States)

    Kim, Sang Tae; Shin, Yeonwoo; Yun, Pil Sang; Bae, Jong Uk; Chung, In Jae; Jeong, Jae Kyeong

    2017-09-01

    This paper proposes a new defect engineering concept for low-cost In- and Ga-free zinc tin oxide (ZTO) thin-film transistors (TFTs). This concept is comprised of capping ZTO films with tantalum (Ta) and a subsequent modest thermal annealing treatment at 200 °C. The Ta-capped ZTO TFTs exhibited a remarkably high carrier mobility of 70.8 cm2/Vs, low subthreshold gate swing of 0.18 V/decade, threshold voltage of -1.3 V, and excellent ION/OFF ratio of 2 × 108. The improvement (> two-fold) in the carrier mobility compared to the uncapped ZTO TFT can be attributed to the effective reduction of the number of adverse tailing trap states, such as hydroxyl groups or oxygen interstitial defects, which stems from the scavenging effect of the Ta capping layer on the ZTO channel layer. Furthermore, the Ta-capped ZTO TFTs showed excellent positive and negative gate bias stress stabilities. [Figure not available: see fulltext.

  13. Cooling Concepts for High Power Density Magnetic Devices

    Science.gov (United States)

    Biela, Juergen; Kolar, Johann W.

    In the area or power electronics there is a general trend to higher power densities. In order to increase the power density the systems must be designed optimally concerning topology, semiconductor selection, etc. and the volume of the components must be decreased. The decreasing volume comes along with a reduced surface for cooling. Consequently, new cooling methods are required. In the paper an indirect air cooling system for magnetic devices which combines the transformer with a heat sink and a heat transfer component is presented. Moreover, an analytic approach for calculating the temperature distribution is derived and validated by measurements. Based on these equations a transformer with an indirect air cooling system is designed for a 10kW telecom power supply.

  14. High Volumetric Energy Density Hybrid Supercapacitors Based on Reduced Graphene Oxide Scrolls.

    Science.gov (United States)

    Rani, Janardhanan R; Thangavel, Ranjith; Oh, Se-I; Woo, Jeong Min; Chandra Das, Nayan; Kim, So-Yeon; Lee, Yun-Sung; Jang, Jae-Hyung

    2017-07-12

    The low volumetric energy density of reduced graphene oxide (rGO)-based electrodes limits its application in commercial electrochemical energy storage devices that require high-performance energy storage capacities in small volumes. The volumetric energy density of rGO-based electrode materials is very low due to their low packing density. A supercapacitor with enhanced packing density and high volumetric energy density is fabricated using doped rGO scrolls (GFNSs) as the electrode material. The restacking of rGO sheets is successfully controlled through synthesizing the doped scroll structures while increasing the packing density. The fabricated cell exhibits an ultrahigh volumetric energy density of 49.66 Wh/L with excellent cycling stability (>10 000 cycles). This unique design strategy for the electrode material has significant potential for the future supercapacitors with high volumetric energy densities.

  15. Trade-off between morphology, extended defects, and compositional fluctuation induced carrier localization in high In-content InGaN films

    Energy Technology Data Exchange (ETDEWEB)

    Ju, James; Loitsch, Bernhard; Stettner, Thomas; Schuster, Fabian; Stutzmann, Martin; Koblmüller, Gregor, E-mail: Gregor.Koblmueller@wsi.tum.de [Walter Schottky Institut and Physik Department, Technische Universität München, Garching 85748 (Germany)

    2014-08-07

    We elucidate the role of growth parameters (III/N flux ratio, temperature T{sub G}) on the morphological and structural properties, as well as compositional homogeneity and carrier localization effects of high In-content (x(In) > 0.75) In–polar InGaN films grown by plasma–assisted molecular beam epitaxy (PAMBE). Variations in III/N flux ratio evidence that higher excess of In yields higher threading dislocation densities as well as larger compositional inhomogeneity as measured by x-ray diffraction. Most interestingly, by variation of growth temperature T{sub G} we find a significant trade-off between improved morphological quality and compositional homogeneity at low–T{sub G} (∼450–550 °C) versus improved threading dislocation densities at high–T{sub G} (∼600–630 °C), as exemplified for InGaN films with x(In) = 0.9. The enhanced compositional homogeneity mediated by low–T{sub G} growth is confirmed by systematic temperature-dependent photoluminescence (PL) spectroscopy data, such as lower PL peakwidths, >5× higher PL efficiency (less temperature-induced quenching) and a distinctly different temperature-dependent S-shape behavior of the PL peak energy. From these, we find that the carrier localization energy is as low as ∼20 meV for low–T{sub G} grown films (T{sub G} = 550 °C), while it rises to ∼70 meV for high–T{sub G} grown films (T{sub G} = 630 °C) right below the onset of In–N dissociation. These findings point out that for the kinetically limited metal-rich PAMBE growth of high In-content InGaN a III/N flux ratio of ∼1 and low-to-intermediate T{sub G} are required to realize optically more efficient materials.

  16. Publications of Proceedings for the RF 2005 7th Workshop on High Energy Density and High Power RF

    Energy Technology Data Exchange (ETDEWEB)

    Luhmann, Jr, N C

    2006-01-01

    The University of California, Davis hosted the High Energy Density and High Power RF 7th Workshop on High Energy Density and High Power RF in Kalamata, Greece, 13-17 June, 2005. The Proceedings cost was supported by these funds from the U.S. Department of Energy. The Proceedings was published through the American Institute of Physics.

  17. Experimental and Ab Initio Ultrafast Carrier Dynamics in Plasmonic Nanoparticles

    Science.gov (United States)

    Brown, Ana M.; Sundararaman, Ravishankar; Narang, Prineha; Schwartzberg, Adam M.; Goddard, William A.; Atwater, Harry A.

    2017-02-01

    Ultrafast pump-probe measurements of plasmonic nanostructures probe the nonequilibrium behavior of excited carriers, which involves several competing effects obscured in typical empirical analyses. Here we present pump-probe measurements of plasmonic nanoparticles along with a complete theoretical description based on first-principles calculations of carrier dynamics and optical response, free of any fitting parameters. We account for detailed electronic-structure effects in the density of states, excited carrier distributions, electron-phonon coupling, and dielectric functions that allow us to avoid effective electron temperature approximations. Using this calculation method, we obtain excellent quantitative agreement with spectral and temporal features in transient-absorption measurements. In both our experiments and calculations, we identify the two major contributions of the initial response with distinct signatures: short-lived highly nonthermal excited carriers and longer-lived thermalizing carriers.

  18. Experimental and ab initio ultrafast carrier dynamics in plasmonic nanoparticles

    CERN Document Server

    Brown, Ana M; Narang, Prineha; Schwartzberg, Adam M; Goddard, William A; Atwater, Harry A

    2016-01-01

    Ultrafast pump-probe measurements of plasmonic nanostructures probe the non-equilibrium behavior of excited carriers, which involves several competing effects obscured in typical empirical analyses. Here we present pump-probe measurements of plasmonic nanoparticles along with a complete theoretical description based on first-principles calculations of carrier dynamics and optical response, free of any fitting parameters. We account for detailed electronic-structure effects in the density of states, excited carrier distributions, electron-phonon coupling, and dielectric functions which allow us to avoid effective electron temperature approximations. Using this calculation method, we obtain excellent quantitative agreement with spectral and temporal features in transient-absorption measurements. In both our experiments and calculations, we identify the two major contributions of the initial response with distinct signatures: short-lived highly non-thermal excited carriers and longer-lived thermalizing carriers.

  19. Extract of mangosteen increases high density lipoprotein levels in rats fed high lipid

    Directory of Open Access Journals (Sweden)

    Dwi Laksono Adiputro

    2015-12-01

    Full Text Available BACKGROUND In cardiovascular medicine, Garcinia mangostana has been used as an antioxidant to inhibit oxidation of low density lipoproteins and as an antiobesity agent. The effect of Garcinia mangostana on hyperlipidemia is unknown. The aim of this study was to evaluate the effect of an ethanolic extract of Garcinia mangostana pericarp on lipid profile in rats fed a high lipid diet. METHODS A total of 40 rats were divided into five groups control, high lipid diet, and high lipid diet + ethanolic extract of Garcinia mangostana pericarp at dosages of 200, 400, and 800 mg/kg body weight. The control group received a standard diet for 60 days. The high lipid diet group received standard diet plus egg yolk, goat fat, cholic acid, and pig fat for 60 days with or without ethanolic extract of Garcinia mangostana pericarp by the oral route. After 60 days, rats were anesthesized with ether for collection of blood by cardiac puncture. Analysis of blood lipid profile comprised colorimetric determination of cholesterol, triglyceride, low density lipoprotein (LDL, and high density lipoprotein (HDL. RESULTS From the results of one-way ANOVA it was concluded that there were significant between-group differences in cholesterol, trygliceride, LDL, and HDL levels (p=0.000. Ethanolic extract of Garcinia mangostana pericarp significantly decreased cholesterol, trygliceride, and LDL levels, starting at 400 mg/kg body weight (p=0.000. Ethanolic extract of Garcinia mangostana pericarp significantly increased HDL level starting at 200 mg/kg body weight (p=0.000. CONCLUSION Ethanolic extract of Garcinia mangostana pericarp has a beneficial effect on lipid profile in rats on a high lipid diet.

  20. Effects of high density on spacing behaviour and reproduction in Akodon azarae: A fencing experiment

    Science.gov (United States)

    Ávila, Belén; Bonatto, Florencia; Priotto, José; Steinmann, Andrea R.

    2016-01-01

    We studied the short term spacing behavioural responses of Pampean grassland mouse (Akodon azarae) with regard to population density in four 0.25 ha enclosures (two control and two experimental) in the 2011 breeding season. Based on the hypothesis that A. azarae breeding females exhibit spacing behaviour, and breeding males show a fusion spatial response, we tested the following predictions: (1) home range size and intrasexual overlap degree of females are independent of population density values; (2) at high population density, home range size of males decreases and the intrasexual home range overlap degree increases. To determine if female reproductive success decreases at high population density, we analyzed pregnancy rate, size and weight of litters, and period until fecundation in both low and high enclosure population density. We found that both males and females varied their home range size in relation to population density. Although male home ranges were always bigger than those of females in populations with high density, home range sizes of both sexes decreased. Females kept exclusive home ranges independent of density values meanwhile males decreased home range overlap in high breeding density populations. Although females produced litters of similar size in both treatments, weight of litter, pregnant rate and period until fecundation varied in relation to population density. Our results did not support the hypothesis that at high density females of A. azarae exhibit spacing behaviour neither that males exhibit a fusion spatial response.