WorldWideScience

Sample records for enhanced andreev transport

  1. Enhanced Andreev reflection in gapped graphene

    Science.gov (United States)

    Majidi, Leyla; Zareyan, Malek

    2012-08-01

    We theoretically demonstrate unusual features of superconducting proximity effect in gapped graphene that presents a pseudospin symmetry-broken ferromagnet with a net pseudomagnetization. We find that the presence of a band gap makes the Andreev conductance of graphene superconductor/pseudoferromagnet (S/PF) junction to behave similar to that of a graphene ferromagnet-superconductor junction. The energy gap ΔN can enhance the pseudospin inverted Andreev conductance of S/PF junction to reach a limiting maximum value for ΔN≫μ, which depending on the bias voltage can be larger than the value for the corresponding junction with no energy gap. We further demonstrate a damped-oscillatory behavior for the local density of states of the PF region of S/PF junction and a long-range crossed Andreev reflection process in PF/S/PF structure with antiparallel alignment of pseudomagnetizations of PFs, which confirm that, in this respect, the gapped normal graphene behaves like a ferromagnetic graphene.

  2. Photon-assisted Andreev transport and sub-gap structures

    DEFF Research Database (Denmark)

    Wildt, M; Kutchinsky, Jonatan; Taboryski, Rafael Jozef

    2000-01-01

    We report new measurements of microwave-induced perturbations of the sub-harmonic energy gap structures in the current-voltage characteristics of superconductor-semiconductor-superconductor junctions. Around the sub-gap bias voltages associated with the enhanced quasi-particle transfer mediated...... by multiple Andreev reflection processes we observe microwave induced satellites, shifted in voltage by multiples of hf/en, where hf is the photon energy and n is the number of quasi-particle traversals as determined by the Andreev processes. The observed behavior is the analogue of the so-called photon...

  3. Magnetoanisotropic spin-triplet Andreev reflection in ferromagnet-Ising superconductor junctions

    Science.gov (United States)

    Lv, Peng; Zhou, Yan-Feng; Yang, Ning-Xuan; Sun, Qing-Feng

    2018-04-01

    We theoretically study the electronic transport through a ferromagnet-Ising superconductor junction. A tight-binding Hamiltonian describing the Ising superconductor is presented. Then by combining the nonequilibrium Green's function method, the expressions of Andreev reflection coefficient and conductance are obtained. A strong magnetoanisotropic spin-triplet Andreev reflection is shown, and the magnetoanisotropic period is π instead of 2 π as in the conventional magnetoanisotropic system. We demonstrate a significant increase of the spin-triplet Andreev reflection for the single-band Ising superconductor. Furthermore, the dependence of the Andreev reflection on the incident energy and incident angle are also investigated. A complete Andreev reflection can occur when the incident energy is equal to the superconducting gap, regardless of the Fermi energy (spin polarization) of the ferromagnet. For the suitable oblique incidence, the spin-triplet Andreev reflection can be strongly enhanced. In addition, the conductance spectroscopies of both zero bias and finite bias are studied, and the influence of gate voltage, exchange energy, and spin-orbit coupling on the conductance spectroscopy are discussed in detail. The conductance exhibits a strong magnetoanisotropy with period π as the Andreev reflection coefficient. When the magnetization direction is parallel to the junction plane, a large conductance peak always emerges at the superconducting gap. This work offers a comprehensive and systematic study of the spin-triplet Andreev reflection and has an underlying application of π -periodic spin valve in spintronics.

  4. Decay Lengths for Diffusive Transport Activated by Andreev Reflections in Al/n-GaAs/Al Superconductor-Semiconductor-Superconductor Junctions

    DEFF Research Database (Denmark)

    Kutchinsky, Jonatan; Taboryski, Rafael Jozef; Clausen, Thomas

    1997-01-01

    In a highly doped GaAs semiconductor with superconducting contacts of Al, clear conductance peaks are observed at zero voltage bias and at V = +/-2 Delta/e, +/-Delta/e. The subharmonic energy gap structure originates from Andreev scattering with diffusive, but energy conserving, transport in the ...

  5. Experimental investigation of supercurrent enhancement in S-N-S junctions by non-equilibrium injection into supercurrent-carrying bound Andreev states

    DEFF Research Database (Denmark)

    Kutchinsky, Jonatan; Taboryski, Rafael Jozef; Sørensen, C B

    2001-01-01

    We report measurements on three-terminal superconductor-semiconductor-superconductor injection devices demonstrating enhancement of the supercurrent by injection from a superconducting injector electrode. Two other electrodes were used to form the detector junction. Applying a small voltage...... of enhancement of the supercurrent by non-equilibrium injection into bound supercurrent-carrying Andreev states. The effect persists to temperatures where the equilibrium supercurrent has vanished. (C) 2001 Elsevier Science B.V. All rights reserved....

  6. Specular Andreev reflection in graphene-based superconducting junction with substate-induced spin orbit interaction

    Energy Technology Data Exchange (ETDEWEB)

    Bai, Chunxu, E-mail: chunxu_bai@semi.ac.cn [School of Physics, Anyang Normal University, Anyang 455000 (China); Yang, Yanling [School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China); School of Physics, Anyang Normal University, Anyang 455000 (China)

    2016-08-26

    Based on the Dirac–Bogoliubov–de Gennes equation, the chirality-resolved transport properties through a ballistic graphene-based superconducting heterojunction with both the Rashba and the Dresselhaus spin orbit interaction have been investigated. Our results show that, in contrast to the retro-Andreev reflection suppressed by the spin orbit interaction (SOI), the specular Andreev reflection (SAR) can be enhanced largely by the SOI. Moreover, the Fabry–Perot interferences in the barrier region lead to the oscillating feature of the tunneling conductance. It is anticipated to apply the qualitative different results to diagnose the SAR in single layer graphene in the presence of both kinds of the SOI. - Highlights: • The retro-Andreev reflection in graphene is suppressed by the spin orbit interaction. • The specular Andreev reflection in graphene can be enhanced largely by the spin orbit interaction. • The Fabry–Perot interferences in the graphene-based barrier lead to the oscillating feature of the tunneling conductance. • The spin orbit interaction is also vital in diagnosing the specular Andreev reflection in graphene.

  7. Specular Andreev reflection in graphene-based superconducting junction with substate-induced spin orbit interaction

    International Nuclear Information System (INIS)

    Bai, Chunxu; Yang, Yanling

    2016-01-01

    Based on the Dirac–Bogoliubov–de Gennes equation, the chirality-resolved transport properties through a ballistic graphene-based superconducting heterojunction with both the Rashba and the Dresselhaus spin orbit interaction have been investigated. Our results show that, in contrast to the retro-Andreev reflection suppressed by the spin orbit interaction (SOI), the specular Andreev reflection (SAR) can be enhanced largely by the SOI. Moreover, the Fabry–Perot interferences in the barrier region lead to the oscillating feature of the tunneling conductance. It is anticipated to apply the qualitative different results to diagnose the SAR in single layer graphene in the presence of both kinds of the SOI. - Highlights: • The retro-Andreev reflection in graphene is suppressed by the spin orbit interaction. • The specular Andreev reflection in graphene can be enhanced largely by the spin orbit interaction. • The Fabry–Perot interferences in the graphene-based barrier lead to the oscillating feature of the tunneling conductance. • The spin orbit interaction is also vital in diagnosing the specular Andreev reflection in graphene.

  8. Andreev reflection in monolayer MoS2

    Science.gov (United States)

    Majidi, Leyla; Rostami, Habib; Asgari, Reza

    2014-01-01

    Andreev reflection in a monolayer molybdenum disulfide superconducting-normal (S/N) hybrid junction is investigated. We find, by using a modified Dirac Hamiltonian and the scattering formalism, that the perfect Andreev reflection happens at normal incidence with p-doped S and N regions. The probability of the Andreev reflection and the resulting Andreev conductance, in this system, are demonstrated to be large in comparison with the corresponding gapped graphene structure. We further investigate the effect of a topological term (β ) in the Hamiltonian and show that it results in an enhancement of the Andreev conductance with p-doped S and N regions, while in the corresponding structure with an n-doped S region it is strongly reducible in comparison. This effect can be explained in terms of the dependence of the Andreev reflection probability on the sign of β and the chemical potential in the superconducting region.

  9. Coherence-enhanced phase-dependent dissipation in long SNS Josephson junctions: Revealing Andreev bound state dynamics

    Science.gov (United States)

    Dassonneville, B.; Murani, A.; Ferrier, M.; Guéron, S.; Bouchiat, H.

    2018-05-01

    One of the best known causes of dissipation in ac-driven quantum systems stems from photon absorption causing transitions between levels. Dissipation can also be caused by the retarded response to the time-dependent excitation, and in general gives insight into the system's relaxation times and mechanisms. Here we address the dissipation in a mesoscopic normal wire with superconducting contacts, that sustains a dissipationless supercurrent at zero frequency and that may therefore naively be expected to remain dissipationless at a frequency lower than the superconducting gap. We probe the high-frequency linear response of such a normal metal/superconductor (NS) ring to a time-dependent flux by coupling it to a highly sensitive multimode microwave resonator. Far from being the simple, dissipationless derivative of the supercurrent-versus-phase relation, the ring's ac susceptibility also displays a dissipative component whose phase dependence is a signature of the dynamical processes occurring within the Andreev spectrum. We show how dissipation is driven by the competition between two mechanisms. The first is the relaxation of the Andreev level distribution function, while the second corresponds to microwave-induced transitions within the spectrum. Depending on the relative strength of those contributions, dissipation can be maximal at π , a phase at which the proximity-induced minigap closes, or can be maximal near π /2 , a phase at which the dc supercurrent is maximal. We also find that the dissipative response paradoxically increases at low temperature and can even exceed the normal-state conductance. The results are successfully confronted with theoretical predictions of the Kubo linear response and time-dependent Usadel equations, derived from the Bogoliubov-de Gennes Hamiltonian describing the SNS junction. These experiments thus demonstrate the power of the ac susceptibility measurement of individual hybrid mesoscopic systems in probing in a controlled way

  10. Direct observation of ballistic Andreev reflection

    Science.gov (United States)

    Klapwijk, T. M.; Ryabchun, S. A.

    2014-12-01

    An overview is presented of experiments on ballistic electrical transport in inhomogeneous superconducting systems which are controlled by the process of Andreev reflection. The initial experiments based on the coexistence of a normal phase and a superconducting phase in the intermediate state led to the concept itself. It was followed by a focus on geometrically inhomogeneous systems like point contacts, which provided a very clear manifestation of the energy and direction dependence of the Andreev reflection process. The point contacts have recently evolved towards the atomic scale owing to the use of mechanical break-junctions, revealing a very detailed dependence of Andreev reflection on the macroscopic phase of the superconducting state. In present-day research, the superconducting in homogeneity is constructed by clean room technology and combines superconducting materials, for example, with low-dimensional materials and topological insulators. Alternatively, the superconductor is combined with nano-objects, such as graphene, carbon nanotubes, or semiconducting nanowires. Each of these "inhomogeneous systems" provides a very interesting range of properties, all rooted in some manifestation of Andreev reflection.

  11. Proximity effect and Andreev reflection in single-C{sub 60} junctions

    Energy Technology Data Exchange (ETDEWEB)

    Brand, Jonathan; Neel, Nicolas; Kroeger, Joerg [Institut fuer Physik, Technische Universitaet Ilmenau, D-98693 Ilmenau (Germany)

    2016-07-01

    Single C{sub 60} molecules deposited on an ultrathin oxide film on Nb(110) were investigated using a low-temperature scanning tunnelling microscope. Spectroscopy of the differential conductance (dI/dV) in the tunnelling range indicates proximity-induced superconductivity in junctions comprising the oxide layer as well as single C{sub 60} molecules. Andreev reflection is enhanced upon controlled fabrication of tip-surface contacts. With decreasing electrode separation the Bardeen-Cooper-Schrieffer energy gap gradually evolves into a zero-bias peak in dI/dV spectra reflecting the spectroscopic signature of Andreev reflection. The current-voltage characteristics of the tunnelling and contact junctions are well described by the Blonder-Tinkham-Klapwijk theory. Our spectroscopic data evidence the influence of the electrodes' atomic-scale structure on electron transport across normal metal-superconductor interfaces.

  12. Supercurrent Spectroscopy of Andreev States

    Directory of Open Access Journals (Sweden)

    L. Bretheau

    2013-12-01

    Full Text Available We measure the excitation spectrum of a superconducting atomic contact. In addition to the usual continuum above the superconducting gap, the single-particle excitation spectrum contains discrete, spin-degenerate Andreev levels inside the gap. Quasiparticle excitations are induced by a broadband on-chip microwave source and detected by measuring changes in the supercurrent flowing through the atomic contact. Since microwave photons excite quasiparticles in pairs, two types of transitions are observed: Andreev transitions, which consist of putting two quasiparticles in an Andreev level, and transitions to odd states with a single quasiparticle in an Andreev level and the other one in the continuum. In contrast to absorption spectroscopy, supercurrent spectroscopy allows detection of long-lived odd states.

  13. Fano effect and Andreev bound states in T-shape double quantum dots

    International Nuclear Information System (INIS)

    Calle, A.M.; Pacheco, M.; Orellana, P.A.

    2013-01-01

    In this Letter, we investigate the transport through a T-shaped double quantum dot coupled to two normal metal leads left and right and a superconducting lead. Analytical expressions of Andreev transmission and local density of states of the system at zero temperature have been obtained. We study the role of the superconducting lead in the quantum interferometric features of the double quantum dot. We report for first time the Fano effect produced by Andreev bound states in a side quantum dot. Our results show that as a consequence of quantum interference and proximity effect, the transmission from normal to normal lead exhibits Fano resonances due to Andreev bound states. We find that this interference effect allows us to study the Andreev bound states in the changes in the conductance between two normal leads. - Highlights: • Transport properties of a double quantum dot coupled in T-shape configuration to conducting and superconducting leads are studied. • We report Fano antiresonances in the normal transmission due to the Andreev reflections in the superconducting lead. • We report for first time the Fano effect produced by Andreev bound states in a side quantum dot. • Fano effect allows us to study the Andreev bound states in the changes in the conductance between two normal leads. • Andreev bound states survives even for strong dot-superconductor coupling

  14. Toy models of crossed Andreev reflection

    International Nuclear Information System (INIS)

    Melin, R; Jirari, H; Peysson, S

    2003-01-01

    We propose toy models of crossed Andreev reflection in multiterminal hybrid structures containing out-of-equilibrium conductors. We apply the description to two possible experiments: (i) to a device containing a large quantum dot inserted in a crossed Andreev reflection circuit, and (ii) to a device containing an Aharonov-Bohm loop inserted in a crossed Andreev reflection circuit

  15. Transmission and Andreev reflection in one-dimensional chain with randomly doped superconducting grains

    International Nuclear Information System (INIS)

    Hu Dongsheng; Xiong Shijie

    2002-01-01

    We investigate the transport properties and Andreev reflection in one-dimensional (1D) systems with randomly doped superconducting grains. The superconducting grains are described by the Bogoliubov-de Gene Hamiltonian and the conductance is calculated by using the transfer matrix method and Landauer-Buettiker formula. It is found that although the quasiparticle states are localized due to the randomness and the low dimensionality, the conductance is still kept finite in the thermodynamical limit due to the Andreev reflection. We also investigate the effect of correlation of disorder in such systems and the results show the delocalization of quasiparticle states and suppression of Andreev reflection in a wide energy window

  16. Fano-Andreev effect in Quantum Dots in Kondo regime

    Science.gov (United States)

    Orellana, Pedro; Calle, Ana Maria; Pacheco, Monica; Apel, Victor

    In the present work, we investigate the transport through a T-shaped double quantum dot system coupled to two normal leads and to a superconducting lead. We study the role of the superconducting lead in the quantum interferometric features of the double quantum dot and by means of a slave boson mean field approximation at low temperature regime. We inquire into the influence of intradot interactions in the electronic properties of the system as well. Our results show that Fano resonances due to Andreev bound states are exhibited in the transmission from normal to normal lead as a consequence of quantum interference and proximity effect. This Fano effect produced by Andreev bound states in a side quantum dot was called Fano-Andreev effect, which remains valid even if the electron-electron interaction are taken into account, that is, the Fano-Andreev effect is robust against e-e interactions even in Kondo regime. We acknowledge the financial support from FONDECYT program Grants No. 3140053 and 11400571.

  17. Andreev molecules in semiconductor nanowire double quantum dots.

    Science.gov (United States)

    Su, Zhaoen; Tacla, Alexandre B; Hocevar, Moïra; Car, Diana; Plissard, Sébastien R; Bakkers, Erik P A M; Daley, Andrew J; Pekker, David; Frolov, Sergey M

    2017-09-19

    Chains of quantum dots coupled to superconductors are promising for the realization of the Kitaev model of a topological superconductor. While individual superconducting quantum dots have been explored, control of longer chains requires understanding of interdot coupling. Here, double quantum dots are defined by gate voltages in indium antimonide nanowires. High transparency superconducting niobium titanium nitride contacts are made to each of the dots in order to induce superconductivity, as well as probe electron transport. Andreev bound states induced on each of dots hybridize to define Andreev molecular states. The evolution of these states is studied as a function of charge parity on the dots, and in magnetic field. The experiments are found in agreement with a numerical model.Quantum dots in a nanowire are one possible approach to creating a solid-state quantum simulator. Here, the authors demonstrate the coupling of electronic states in a double quantum dot to form Andreev molecule states; a potential building block for longer chains suitable for quantum simulation.

  18. Acoustically enhanced heat transport

    Energy Technology Data Exchange (ETDEWEB)

    Ang, Kar M.; Hung, Yew Mun; Tan, Ming K., E-mail: tan.ming.kwang@monash.edu [School of Engineering, Monash University Malaysia, 47500 Bandar Sunway, Selangor (Malaysia); Yeo, Leslie Y. [Micro/Nanophysics Research Laboratory, RMIT University, Melbourne, VIC 3001 (Australia); Friend, James R. [Department of Mechanical and Aerospace Engineering, University of California, San Diego, California 92093 (United States)

    2016-01-15

    We investigate the enhancement of heat transfer in the nucleate boiling regime by inducing high frequency acoustic waves (f ∼ 10{sup 6} Hz) on the heated surface. In the experiments, liquid droplets (deionized water) are dispensed directly onto a heated, vibrating substrate. At lower vibration amplitudes (ξ{sub s} ∼ 10{sup −9} m), the improved heat transfer is mainly due to the detachment of vapor bubbles from the heated surface and the induced thermal mixing. Upon increasing the vibration amplitude (ξ{sub s} ∼ 10{sup −8} m), the heat transfer becomes more substantial due to the rapid bursting of vapor bubbles happening at the liquid-air interface as a consequence of capillary waves travelling in the thin liquid film between the vapor bubble and the air. Further increases then lead to rapid atomization that continues to enhance the heat transfer. An acoustic wave displacement amplitude on the order of 10{sup −8} m with 10{sup 6} Hz order frequencies is observed to produce an improvement of up to 50% reduction in the surface temperature over the case without acoustic excitation.

  19. Andreev reflection through a ferromagnet-quantum dot-superconductor system with intradot Coulomb correlations

    Directory of Open Access Journals (Sweden)

    Rudziński Wojciech

    2013-01-01

    Full Text Available Spin-dependent tunneling through a quantum dot coupled to one ferromagnetic and one superconducting electrodes is studied in the Andreev reflection (AR regime. Electrical conductance is calculated within the nonequilibrium Green function technique. Effects due to a competition between the Coulomb correlations on the dot and intradot spin-flip processes are considered in the linear transport regime and for different coupling strengths between the dot and the external electrodes. It is shown that when a coherent spin rotation is present on the dot, Coulomb interactions may lead to a significant enhancement of the AR tunneling current and even to the perfect AR transmission. Origin of occurrence of a variety of the multipeak structure of the linear conductance is also discussed.

  20. Gate-tunable Andreev bound states in InSb nanowire Josephson junction

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Ning; Li, Sen; Fan, Dingxun; Xu, Hongqi [Key Laboratory for the Physics and Chemistry of Nanodevices, Department of Electronics, Peking University, Beijing 100871 (China); Caroff, Philippe [Division of Solid State Physics, Lund University, P. O. Box 118, S-221 00 Lund (Sweden)

    2016-07-01

    Hybrid InSb nanowire-superconductor devices are promising candidates for investigating Majorana modes in solid-state devices and future technologies of topological quantum manipulation. Here, we report low-temperature transport measurements on an individual InSb nanowire quantum dot coupled to superconducting contacts that exhibit an interplay between the Kondo effects and superconductivity. We observed two types of subgap resonance states within the superconducting gap, which can be attributed to gate-tunable Andreev bound states in Coulomb valleys with different Kondo temperatures. The presence of the gate-tunable 0 and pi junction allow us to investigate the fundamental 0- pi transition. Detailed magnetic field and temperature evolution of level spectroscopy demonstrate different behavior of two types of the Andreev bound states. Our results exhibit that the InSb nanowires can provide a promising platform for exploring phase coherence transport and the effect of spin-orbit coupling in semiconductor nanowire-superconductor hybrid device.

  1. Andreev bound states. Some quasiclassical reflections

    International Nuclear Information System (INIS)

    Lin, Y.; Leggett, A. J.

    2014-01-01

    We discuss a very simple and essentially exactly solvable model problem which illustrates some nice features of Andreev bound states, namely, the trapping of a single Bogoliubov quasiparticle in a neutral s-wave BCS superfluid by a wide and shallow Zeeman trap. In the quasiclassical limit, the ground state is a doublet with a splitting which is proportional to the exponentially small amplitude for “normal” reflection by the edges of the trap. We comment briefly on a prima facie paradox concerning the continuity equation and conjecture a resolution to it

  2. Andreev bound states. Some quasiclassical reflections

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Y., E-mail: yiriolin@illinois.edu; Leggett, A. J. [University of Illinois at Urhana-Champaign, Dept. of Physics (United States)

    2014-12-15

    We discuss a very simple and essentially exactly solvable model problem which illustrates some nice features of Andreev bound states, namely, the trapping of a single Bogoliubov quasiparticle in a neutral s-wave BCS superfluid by a wide and shallow Zeeman trap. In the quasiclassical limit, the ground state is a doublet with a splitting which is proportional to the exponentially small amplitude for “normal” reflection by the edges of the trap. We comment briefly on a prima facie paradox concerning the continuity equation and conjecture a resolution to it.

  3. Andreev Reflection Spectroscopy of Nb-doped Bi2Se3 Topological Insulator

    Science.gov (United States)

    Kurter, C.; Finck, A. D. K.; Qiu, Y.; Huemiller, E.; Weis, A.; Atkinson, J.; Medvedeva, J.; Hor, Y. S.; van Harlingen, D. J.

    2015-03-01

    Doped topological insulators are speculated to realize p-wave superconductivity with unusual low energy quasiparticles, such as surface Andreev bound states. We present point contact spectroscopy of thin exfoliated flakes of Nb-doped Bi2Se3 where superconductivity persists up to ~ 1 K, compared to 3.2 K in bulk crystals. The critical magnetic field is strongly anisotropic, consistent with quasi-2D behavior. Andreev reflection measurements of devices with low resistance contacts result in prominent BTK-like behavior with an enhanced conductance plateau at low bias. For high resistance contacts, we observe a split zero bias conductance anomaly and additional features at the superconducting gap. Our results suggest that this material is a promising platform for studying topological superconductivity. We acknowledge support from Microsoft Project Q.

  4. 23 CFR 710.511 - Transportation enhancements.

    Science.gov (United States)

    2010-04-01

    ... 23 Highways 1 2010-04-01 2010-04-01 false Transportation enhancements. 710.511 Section 710.511 Highways FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION RIGHT-OF-WAY AND ENVIRONMENT RIGHT-OF-WAY AND REAL ESTATE Property Acquisition Alternatives § 710.511 Transportation enhancements. (a...

  5. Specular Andreev reflection in thin films of topological insulators

    Science.gov (United States)

    Majidi, Leyla; Asgari, Reza

    2016-05-01

    We theoretically reveal the possibility of specular Andreev reflection in a thin film topological insulator normal-superconductor (N/S) junction in the presence of a gate electric field. The probability of specular Andreev reflection increases with the electric field, and electron-hole conversion with unit efficiency happens in a wide experimentally accessible range of the electric field. We show that perfect specular Andreev reflection can occur for all angles of incidence with a particular excitation energy value. In addition, we find that the thermal conductance of the structure displays exponential dependence on the temperature. Our results reveal the potential of the proposed topological insulator thin-film-based N/S structure for the realization of intraband specular Andreev reflection.

  6. Andreev bound states probed in three-terminal quantum dots

    Science.gov (United States)

    Gramich, J.; Baumgartner, A.; Schönenberger, C.

    2017-11-01

    Andreev bound states (ABSs) are well-defined many-body quantum states that emerge from the hybridization of individual quantum dot (QD) states with a superconductor and exhibit very rich and fundamental phenomena. We demonstrate several electron transport phenomena mediated by ABSs that form on three-terminal carbon nanotube (CNT) QDs, with one superconducting (S) contact in the center and two adjacent normal-metal (N) contacts. Three-terminal spectroscopy allows us to identify the coupling to the N contacts as the origin of the Andreev resonance (AR) linewidths and to determine the critical coupling strengths to S, for which a ground state (or quantum phase) transition in such S-QD systems can occur. In addition, we ascribe replicas of the lowest-energy ABS resonance to transitions between the ABS and odd-parity excited QD states, a process we call excited state ABS resonances. In the conductance between the two N contacts we find a characteristic pattern of positive and negative differential subgap conductance, which we explain by considering two nonlocal processes, the creation of Cooper pairs in S by electrons from both N terminals, and a transport mechanism we call resonant ABS tunneling, possible only in multiterminal QD devices. In the latter process, electrons are transferred via the ABS without effectively creating Cooper pairs in S. The three-terminal geometry also allows spectroscopy experiments with different boundary conditions, for example by leaving S floating. Surprisingly, we find that, depending on the boundary conditions and the device parameters, the experiments either show single-particle Coulomb blockade resonances, ABS characteristics, or both in the same measurements, seemingly contradicting the notion of ABSs replacing the single-particle states as eigenstates of the QD. We qualitatively explain these results as originating from the finite time scale required for the coherent oscillations between the superposition states after a single

  7. Phase Coherence and Andreev Reflection in Topological Insulator Devices

    Directory of Open Access Journals (Sweden)

    A. D. K. Finck

    2014-11-01

    Full Text Available Topological insulators (TIs have attracted immense interest because they host helical surface states. Protected by time-reversal symmetry, they are robust to nonmagnetic disorder. When superconductivity is induced in these helical states, they are predicted to emulate p-wave pairing symmetry, with Majorana states bound to vortices. Majorana bound states possess non-Abelian exchange statistics that can be probed through interferometry. Here, we take a significant step towards Majorana interferometry by observing pronounced Fabry-Pérot oscillations in a TI sandwiched between a superconducting and a normal lead. For energies below the superconducting gap, we observe a doubling in the frequency of the oscillations, arising from an additional phase from Andreev reflection. When a magnetic field is applied perpendicular to the TI surface, a number of very sharp and gate-tunable conductance peaks appear at or near zero energy, which has consequences for interpreting spectroscopic probes of Majorana fermions. Our results demonstrate that TIs are a promising platform for exploring phase-coherent transport in a solid-state system.

  8. Andreev reflections and the quantum physics of black holes

    Science.gov (United States)

    Manikandan, Sreenath K.; Jordan, Andrew N.

    2017-12-01

    We establish an analogy between superconductor-metal interfaces and the quantum physics of a black hole, using the proximity effect. We show that the metal-superconductor interface can be thought of as an event horizon and Andreev reflection from the interface is analogous to the Hawking radiation in black holes. We describe quantum information transfer in Andreev reflection with a final state projection model similar to the Horowitz-Maldacena model for black hole evaporation. We also propose the Andreev reflection analogue of Hayden and Preskill's description of a black hole final state, where the black hole is described as an information mirror. The analogy between crossed Andreev reflections and Einstein-Rosen bridges is discussed: our proposal gives a precise mechanism for the apparent loss of quantum information in a black hole by the process of nonlocal Andreev reflection, transferring the quantum information through a wormhole and into another universe. Given these established connections, we conjecture that the final quantum state of a black hole is exactly the same as the ground state wave function of the superconductor/superfluid in the Bardeen-Cooper-Schrieffer (BCS) theory of superconductivity; in particular, the infalling matter and the infalling Hawking quanta, described in the Horowitz-Maldacena model, forms a Cooper pairlike singlet state inside the black hole. A black hole evaporating and shrinking in size can be thought of as the analogue of Andreev reflection by a hole where the superconductor loses a Cooper pair. Our model does not suffer from the black hole information problem since Andreev reflection is unitary. We also relate the thermodynamic properties of a black hole to that of a superconductor, and propose an experiment which can demonstrate the negative specific heat feature of black holes in a growing/evaporating condensate.

  9. Localized excitations in superconducting point contacts: probing the Andreev doublet

    International Nuclear Information System (INIS)

    Bretheau, L.

    2013-01-01

    The Josephson effect describes the coherent coupling between superconductors and the resulting supercurrent. Microscopically, it arises from the existence of discrete quasiparticle states, localized at the weak link, the Andreev bound states. They come in doublets in each conduction channel of the weak link, with energies symmetric about the Fermi energy and opposite supercurrents. Each Andreev doublet gives rise to four states: the ground state |-> and the excited state |+>, with even parity, and the excited odd states |↑> and |↓>. Is it possible to address and control Andreev doublets? This thesis describes two sets of experiments designed to answer this question using the most basic Josephson element, a one-atom contact between two superconducting electrodes. In a first experiment, we have observed and characterized the excited odd states |↑> and |↓>. As expected for a spin-degenerate system, they do not carry supercurrent. In this experiment the excitation was uncontrolled and resulted from trapping of spurious quasiparticles. We have measured the lifetime of the odd states: under some condition, it is found to exceed 100 μs. The second experiment is a photon-absorption spectroscopy of the Andreev doublet. It was performed by using a Josephson junction as an integrated on-chip microwave emitter and detector. The observed Andreev transitions correspond to excitation from the ground state |->to the excited even state |+>, and are well accounted for by our quantum model. This result opens the way to coherent manipulation of this two level system. The direct observation of the excited Andreev state, either by quasiparticle-injection or photon-absorption, strongly supports the mesoscopic theory of the Josephson effect. It shows that in addition to the phase difference, each channel of a Josephson weak link possesses an internal fermionic degree of freedom. It could be used to code information in a novel type of superconducting qubit. (author) [fr

  10. Angle dependence of Andreev scattering at semiconductor-superconductor interfaces

    DEFF Research Database (Denmark)

    Mortensen, Asger; Flensberg, Karsten; Jauho, Antti-Pekka

    1999-01-01

    We study the angle dependence of the Andreev scattering at a semiconductor-superconductor interface, generalizing the one-dimensional theory of Blonder, Tinkham, and Klapwijk (BTK),An increase of the momentum parallel to the interface leads to suppression of the probability of Andreev reflection...... and increase of the probability of normal reflection. We show that in the presence of a Fermi velocity mismatch between the semiconductor and the superconductor the angles of incidence and transmission are related according to the well-known Snell's law in optics. As a consequence there is a critical angle...

  11. Andreev reflection properties in a parallel mesoscopic circuit with Majorana bound states

    Energy Technology Data Exchange (ETDEWEB)

    Mu, Jin-Tao; Han, Yu [Physics Department, Liaoning University, Shenyang 110036 (China); Gong, Wei-Jiang, E-mail: gwj@mail.neu.edu.cn [College of Sciences, Northeastern University, Shenyang 110819 (China)

    2017-03-15

    We investigate the Andreev reflection in a parallel mesoscopic circuit with Majorana bound states (MBSs). It is found that in such a structure, the Andreev current can be manipulated in a highly efficient way, by the adjustment of bias voltage, dot levels, inter-MBS coupling, and the applied magnetic flux. Besides, the dot-MBS coupling manner is an important factor to modulate the Andreev current, because it influences the period of the conductance oscillation. By discussing the underlying quantum interference mechanism, the Andreev-reflection property is explained in detail. We believe that all the results can assist to understand the nontrivial role of the MBSs in driving the Andreev reflection.

  12. Probing Andreev bound states in one-atom superconducting contacts

    Energy Technology Data Exchange (ETDEWEB)

    Pothier, Hugues; Janvier, Camille; Tosi, Leandro; Girit, Caglar; Goffman, Marcelo; Esteve, Daniel; Urbina, Cristian [Quantronics Group, SPEC, CEA-Saclay (France)

    2015-07-01

    Superconductors are characterized by a dissipationless current. Since the work of Josephson 50 years ago, it is known that a supercurrent can even flow through tunnel junctions between superconductors. This Josephson effect also occurs through any type of ''weak links'' between superconductors: non-superconducting materials, constrictions,.. A unified understanding of the Josephson effect has emerged from a mesoscopic description of weak links. It relies on the existence of doublets of localized states that have energies below the superconducting gap: the Andreev bound states. I will present experiments performed on the simplest conductor possible, a single-atom contact between superconductors, that illustrate these concepts. The most recent work demonstrates time-domain manipulation of quantum superpositions of Andreev bound states.

  13. Shooting quasiparticles from Andreev bound states in a superconducting constriction

    Energy Technology Data Exchange (ETDEWEB)

    Riwar, R.-P.; Houzet, M.; Meyer, J. S. [University of Grenoble Alpes, INAC-SPSMS (France); Nazarov, Y. V., E-mail: Y.V.Nazarov@tudelft.nl [Delft University of Technology, Kavli Institute of NanoScience (Netherlands)

    2014-12-15

    A few-channel superconducting constriction provides a set of discrete Andreev bound states that may be populated with quasiparticles. Motivated by recent experimental research, we study the processes in an a.c. driven constriction whereby a quasiparticle is promoted to the delocalized states outside the superconducting gap and flies away. We distinguish two processes of this kind. In the process of ionization, a quasiparticle present in the Andreev bound state is transferred to the delocalized states leaving the constriction. The refill process involves two quasiparticles: one flies away while another one appears in the Andreev bound state. We notice an interesting asymmetry of these processes. The electron-like quasiparticles are predominantly emitted to one side of the constriction while the hole-like ones are emitted to the other side. This produces a charge imbalance of accumulated quasiparticles, that is opposite on opposite sides of the junction. The imbalance may be detected with a tunnel contact to a normal metal lead.

  14. Enhancing Thermoelectric Performance Using Nonlinear Transport Effects

    Science.gov (United States)

    Jiang, Jian-Hua; Imry, Yoseph

    2017-06-01

    We study nonlinear transport effects on the maximum efficiency and power for both inelastic and elastic thermoelectric generators. The former device refers to phonon-assisted hopping in double quantum dots, while the latter device is represented by elastic tunneling through a single quantum dot. We find that nonlinear thermoelectric transport can lead to enhanced efficiency and power for both types of devices. A comprehensive survey of various quantum-dot energy, temperature, and parasitic heat conduction reveals that the nonlinear transport-induced improvements of the maximum efficiency and power are overall much more significant for inelastic devices than for elastic devices, even for temperature biases as small as Th=1.2 Tc (Th and Tc are the temperatures of the hot and cold reservoirs, respectively). The underlying mechanism is revealed as due to the fact that, unlike the Fermi distribution, the Bose distribution is not bounded when the temperature bias increases. A large flux density of absorbed phonons leads to a great enhancement of the electrical current, output power, and energy efficiency, dominating over the concurrent increase of the parasitic heat current. Our study reveals that nonlinear transport effects can be a useful tool for improving thermoelectric performance.

  15. The effect of radioactive waste storage in Andreev Bay on contamination of the Barents Sea ecosystem

    Science.gov (United States)

    Matishov, G. G.; Ilyin, G. V.; Usyagina, I. S.; Moiseev, D. V.; Dahle, Salve; Kasatkina, N. E.; Valuyskaya, D. A.

    2017-02-01

    The effect of temporary radioactive waste storage on the ecological status of the sea and biota in the littoral of Andreev and Malaya Andreev bays and near the shore of Motovskii Gulf (including the mouth part of the Zapadnaya Litsa Bay) was analyzed. The littoral sediments contaminated by the 137Cs, 90Sr, 238Pu, and 239,240Pu isotopes are located in the zones of constant groundwater discharge on the shores of Andreev and Malaya Andreev bays. The littoral slopes and bottom depressions of the bays accumulate finely dispersed terrigenous material and 137Cs. The investigations have shown that the storage does not exert a significant adverse effect on the radioactive conditions and the status of the sea ecosystems beyond Andreev Bay.

  16. What can Andreev bound states tell us about superconductors?

    Science.gov (United States)

    Millo, Oded; Koren, Gad

    2018-08-06

    Zero-energy Andreev bound states, which manifest themselves in the tunnelling spectra as zero-bias conductance peaks (ZBCPs), are abundant at interfaces between superconductors and other materials and on the nodal surface of high-temperature superconductors. In this review, we focus on the information such excitations can provide on the properties of superconductor systems. First, a general introduction to the physics of Andreev bound states in superconductor/normal metal interfaces is given with a particular emphasis on why they appear at zero energy in d -wave superconductors. Then, specific spectroscopic tunnelling studies of thin films, bilayers and junctions are described, focusing on the corresponding ZBCP features. Scanning tunnelling spectroscopy (STS) studies show that the ZBCPs on the c -axis YBa 2 Cu 3 O 7- δ (YBCO) films are correlated with the surface morphology and appear only in proximity to (110) facets. STS on c -axis La 1.88 Sr 0.12 CuO 4 (LSCO) films exhibiting the 1/8 anomaly shows spatially modulated peaks near zero bias associated with the anti-phase ordering of the d -wave order parameter predicted at this doping level. ZBCPs were also found in micrometre-size edge junctions of YBCO/SrRuO 3 /YBCO, where SrRuO 3 is ferromagnetic. Here, the results are consistent with a crossed Andreev reflection effect (CARE) at the narrow domain walls of the SrRuO 3 ZBCPs measured in STS studies of manganite/cuprate bilayers could not be attributed to CARE because the manganite's domain wall is much larger than the coherence length in YBCO, and instead are attributed to proximity-induced triplet-pairing superconductivity with non-conventional symmetry. And finally, ZBCPs found in junctions of non-intentionally doped topological insulator films of Bi 2 Se 3 and the s -wave superconductor NbN are attributed to proximity-induced p x  + ip y triplet order parameter in the topological material.This article is part of the theme issue 'Andreev bound states'.

  17. Coulomb Blockade and Multiple Andreev Reflection in a Superconducting Single-Electron Transistor

    Science.gov (United States)

    Lorenz, Thomas; Sprenger, Susanne; Scheer, Elke

    2018-06-01

    In superconducting quantum point contacts, multiple Andreev reflection (MAR), which describes the coherent transport of m quasiparticles each carrying an electron charge with m≥3, sets in at voltage thresholds eV = 2Δ /m. In single-electron transistors, Coulomb blockade, however, suppresses the current at low voltage. The required voltage for charge transport increases with the square of the effective charge eV∝ ( me) ^2. Thus, studying the charge transport in all-superconducting single-electron transistors (SSETs) sets these two phenomena into competition. In this article, we present the fabrication as well as a measurement scheme and transport data for a SSET with one junction in which the transmission and thereby the MAR contributions can be continuously tuned. All regimes from weak to strong coupling are addressed. We extend the Orthodox theory by incorporating MAR processes to describe the observed data qualitatively. We detect a new transport process the nature of which is unclear at present. Furthermore, we observe a renormalization of the charging energy when approaching the strong coupling regime.

  18. Ripple enhanced transport of suprathermal alpha particles

    International Nuclear Information System (INIS)

    Tani, K.; Takizuka, T.; Azumi, M.

    1986-01-01

    The ripple enhanced transport of suprathermal alpha particles has been studied by the newly developed Monte-Carlo code in which the motion of banana orbit in a toroidal field ripple is described by a mapping method. The existence of ripple-resonance diffusion has been confirmed numerically. We have developed another new code in which the radial displacement of banana orbit is given by the diffusion coefficients from the mapping code or the orbit following Monte-Carlo code. The ripple loss of α particles during slowing down has been estimated by the mapping model code as well as the diffusion model code. From the comparison of the results with those from the orbit-following Monte-Carlo code, it has been found that all of them agree very well. (author)

  19. Supercurrent and multiple Andreev reflections in micrometer-long ballistic graphene Josephson junctions.

    Science.gov (United States)

    Zhu, Mengjian; Ben Shalom, Moshe; Mishchsenko, Artem; Fal'ko, Vladimir; Novoselov, Kostya; Geim, Andre

    2018-02-08

    Ballistic Josephson junctions are predicted to support a number of exotic physics processess, providing an ideal system to inject the supercurrent in the quantum Hall regime. Herein, we demonstrate electrical transport measurements on ballistic superconductor-graphene-superconductor junctions by contacting graphene to niobium with a junction length up to 1.5 μm. Hexagonal boron nitride encapsulation and one-dimensional edge contacts guarantee high-quality graphene Josephson junctions with a mean free path of several micrometers and record-low contact resistance. Transports in normal states including the observation of Fabry-Pérot oscillations and Sharvin resistance conclusively witness the ballistic propagation in the junctions. The critical current density J C is over one order of magnitude larger than that of the previously reported junctions. Away from the charge neutrality point, the I C R N product (I C is the critical current and R N the normal state resistance of junction) is nearly a constant, independent of carrier density n, which agrees well with the theory for ballistic Josephson junctions. Multiple Andreev reflections up to the third order are observed for the first time by measuring the differential resistance in the micrometer-long ballistic graphene Josephson junctions.

  20. Josephson current and Andreev level dynamics in nanoscale superconducting weak links

    Energy Technology Data Exchange (ETDEWEB)

    Brunetti, Aldo

    2014-11-15

    In this thesis we focus on the interplay between proximity induced superconducting correlations and Coulomb interactions in a Josephson junction: i.e., in a system where two superconductors modeled as two s-wave superconductors at a phase difference φ are contacted by means of a weak link, in our case a quantum dot located in the contact. In the first part we study the Josephson current-phase relation for a multi-level quantum dot tunnel-contacted by two conventional s-waves superconductors. We determine in detail the conditions for observing a finite anomalous Josephson current, i.e. a supercurrent flowing at zero phase difference in a two-level dot with spin-orbit interactions, a weak magnetic (Zeeman) field, and in the presence of Coulomb interactions. This leads to an onset behavior I{sub a}∝sgn(B), interpreted as the sign of an incipient spontaneous breakdown of time-reversal symmetry. Moreover, we will provide conditions for realizing spatially separated - but topologically unprotected - Majorana bound states, whose signature in the system will be detectable via the current-phase relation. In the second part of the thesis, we address the Andreev bound state population dynamics in superconducting weak links (a superconducting 'atomic contact'), in which a poisoning mechanism due to the trapping of single quasiparticles can occur. Our motivation is that quantum coherent superconducting circuits are the most promising candidates for future large-scale quantum information processing devices. Moreover, quasiparticle poisoning has recently been observed in devices which contain a short superconducting weak link with few transport channels. We discuss a novel charge imbalance effect in the continuum quasiparticle population, which is due to phase fluctuations of the environment weakly coupled to the superconducting contact. This coupling enters the system as a transition rate connecting continuum quasiparticles and the Andreev bound state system. The

  1. Majorana fermion modulated nonequilibrium transport through double quantum dots

    International Nuclear Information System (INIS)

    Deng, Ming-Xun; Wang, Rui-Qiang; Ai, Bao-Quan; Yang, Mou; Hu, Liang-Bin; Zhong, Qing-Hu; Wang, Guang-Hui

    2014-01-01

    Nonequilibrium electronic transports through a double-QD-Majorana coupling system are studied with a purpose to extract the information to identify Majorana bound states (MBSs). It is found that MBSs can help form various transport processes, including the nonlocal crossed Andreev reflection, local resonant Andreev reflection, and cotunneling, depending on the relative position of two dot levels. These processes enrich the signature of average currents and noise correlations to probe the nature of MBSs. We further demonstrate the switching between the current peaks of crossed Andreev reflection and cotunneling, which is closely related to the nonlocal nature of Majorana fermions. We also propose effective physical pictures to understand these Majorana-assisted transports. - Highlights: • Majorana fermions are characterized in the signature of currents and noises. • Three types of tunneling mechanisms are realized separately. • The switching of crossed Andreev reflection and cotunneling is realized. • Concrete physical pictures are proposed to understand Majorana-assisted transports

  2. Majorana fermion modulated nonequilibrium transport through double quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Deng, Ming-Xun [Laboratory of Quantum Engineering and Quantum Materials, ICMP and SPTE, South China Normal University, Guangzhou 510006 (China); Wang, Rui-Qiang, E-mail: rqwanggz@163.com [Laboratory of Quantum Engineering and Quantum Materials, ICMP and SPTE, South China Normal University, Guangzhou 510006 (China); Ai, Bao-Quan; Yang, Mou; Hu, Liang-Bin; Zhong, Qing-Hu [Laboratory of Quantum Engineering and Quantum Materials, ICMP and SPTE, South China Normal University, Guangzhou 510006 (China); Wang, Guang-Hui [Laboratory of Nanophotonic Functional Materials and Devices, South China Normal University, Guangzhou 510006 (China)

    2014-06-13

    Nonequilibrium electronic transports through a double-QD-Majorana coupling system are studied with a purpose to extract the information to identify Majorana bound states (MBSs). It is found that MBSs can help form various transport processes, including the nonlocal crossed Andreev reflection, local resonant Andreev reflection, and cotunneling, depending on the relative position of two dot levels. These processes enrich the signature of average currents and noise correlations to probe the nature of MBSs. We further demonstrate the switching between the current peaks of crossed Andreev reflection and cotunneling, which is closely related to the nonlocal nature of Majorana fermions. We also propose effective physical pictures to understand these Majorana-assisted transports. - Highlights: • Majorana fermions are characterized in the signature of currents and noises. • Three types of tunneling mechanisms are realized separately. • The switching of crossed Andreev reflection and cotunneling is realized. • Concrete physical pictures are proposed to understand Majorana-assisted transports.

  3. Enhancing disease surveillance reporting using public transport in ...

    African Journals Online (AJOL)

    Enhancing disease surveillance reporting using public transport in Dodoma District, Central Tanzania. ... LEG Mboera, SF Rumisha, EJ Mwanemile, E Mziwanda, PK Mmbuji ... Full Text: EMAIL FREE FULL TEXT EMAIL FREE FULL TEXT

  4. Mixing enhancement and transport reduction in chaotic advection

    OpenAIRE

    Benzekri , Tounsia; Chandre , Cristel; Leoncini , Xavier; Lima , Ricardo; Vittot , Michel

    2005-01-01

    We present a method for reducing chaotic transport in a model of chaotic advection due to time-periodic forcing of an oscillating vortex chain. We show that by a suitable modification of this forcing, the modified model combines two effects: enhancement of mixing within the rolls and suppression of chaotic transport along the channel.

  5. Nonlocal Andreev reflection and spin current in a three-terminal Aharonov–Bohm interferometer

    International Nuclear Information System (INIS)

    Ju, Peng; Hua-Ling, Yu; Zhi-Guo, Wang

    2009-01-01

    This paper theoretically reports the nonlocal Andreev reflection and spin current in a normal metal-ferromagnetic metal-superconducting Aharonov–Bohm interferometer. It is found that the electronic current and spin current are sensitive to systematic parameters, such as the gate voltage of quantum dots and the external magnetic flux. The electronic current in the normal metal lead results from two competing processes: quasiparticle transmission and nonlocal Andreev reflection. The appearance of zero spin-up electronic current (or spin-down electronic current) signals the existence of nonlocal Andreev reflection, and the presence of zero electronic current results in the appearance of pure spin current. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  6. Signature of a Crossed Andreev Reflection effect (CARE) in YBaCuO/SrRuO3/YBaCuO junctions

    International Nuclear Information System (INIS)

    Aronov, P.; Gad Koren, G.

    2005-01-01

    Full Text:Magnetic properties of SFS and SF ramp-type junctions with Y Ba 2 Cu 3 O 7 -YBaCuO-δ electrodes (S), and the itinerant ferromagnet SrRuO 3 (SrO - F), were investigated. We looked for a crossed Andreev reflection effect (CARE) in which an electron from one magnetic domain in F is Andreev reflected as a hole into an adjacent, oppositely polarized, domain while a pair is transmitted into S. CARE is possible in SrO since the width of its domain walls is of the order of the YBaCuO coherence length (2-3nm). Our junctions behave as typical magnetic tunneling junctions, as the conductance spectra were always asymmetric, and a few showed bound state peaks at finite bias which shifted with field according to the classical Tedrow and Meservey theory. In many of our SFS junctions with a barrier thickness of 10-20nm, a prominent zero bias conductance peak (ZBCP) has been observed. This peak was found to decrease linearly with magnetic field, as expected for Andreev and CARE scattering. In contrast, in SF junctions, the observed ZBCP was found to decrease versus field almost exponentially, in agreement with the Anderson-Appelbaum theory of scattering by magnetic states in F. Thus, transport in our SFS and SF junctions depends strongly on the size of the F layer. We also found that in both cases, the ZBCP height at zero field decreased with increasing magnetic order of the domains in F, in agreement with the CARE mechanism

  7. Giant Andreev backscattering and reentrant resistance in a 2- dimensional electron gas coupled to superconductors

    NARCIS (Netherlands)

    den Hartog, Sander; Wees, B.J. van; Nazarov, Yu.V.; Klapwijk, T.M.; Borghs, G.

    1998-01-01

    We have investigated the superconducting-phase modulated reduction in the resistance of a ballistic quantum point contact (QPC) connected via a disordered 2-dimensional electron gas (2DEG) to superconductors. We show that this reduction is caused by coherent Andreev back scattering of holes through

  8. Andreev spectrum with high spin-orbit interactions: Revealing spin splitting and topologically protected crossings

    Science.gov (United States)

    Murani, A.; Chepelianskii, A.; Guéron, S.; Bouchiat, H.

    2017-10-01

    In order to point out experimentally accessible signatures of spin-orbit interaction, we investigate numerically the Andreev spectrum of a multichannel mesoscopic quantum wire (N) with high spin-orbit interaction coupled to superconducting electrodes (S), contrasting topological and nontopological behaviors. In the nontopological case (square lattice with Rashba interactions), we find that the Kramers degeneracy of Andreev levels is lifted by a phase difference between the S reservoirs except at multiples of π , when the normal quantum wires can host several conduction channels. The level crossings at these points invariant by time-reversal symmetry are not lifted by disorder. Whereas the dc Josephson current is insensitive to these level crossings, the high-frequency admittance (susceptibility) at finite temperature reveals these level crossings and the lifting of their degeneracy at π by a small Zeeman field. We have also investigated the hexagonal lattice with intrinsic spin-orbit interaction in the range of parameters where it is a two-dimensional topological insulator with one-dimensional helical edges protected against disorder. Nontopological superconducting contacts can induce topological superconductivity in this system characterized by zero-energy level crossing of Andreev levels. Both Josephson current and finite-frequency admittance carry then very specific signatures at low temperature of this disorder-protected Andreev level crossing at π and zero energy.

  9. Issues in tokamak/stellarator transport and confinement enhancement mechanisms

    International Nuclear Information System (INIS)

    Perkins, F.W.

    1990-08-01

    At present, the mechanism for anomalous energy transport in low-β toroidal plasmas -- tokamaks and stellarators -- remains unclear, although transport by turbulent E x B velocities associated with nonlinear, fine-scale microinstabilities is a leading candidate. This article discusses basic theoretical concepts of various transport and confinement enhancement mechanisms as well as experimental ramifications which would enable one to distinguish among them and hence identify a dominant transport mechanism. While many of the predictions of fine-scale turbulence are born out by experiment, notable contradictions exist. Projections of ignition margin rest both on the scaling properties of the confinement mechanism and on the criteria for entering enhanced confinement regimes. At present, the greatest uncertainties lie with the basis for scaling confinement enhancement criteria. A series of questions, to be answered by new experimental/theoretical work, is posed to resolve these outstanding contradictions (or refute the fine-scale turbulence model) and to establish confinement enhancement criteria. 73 refs., 4 figs., 5 tabs

  10. Manipulatable Andreev reflection due to the interplay between the DIII-class topological and s-wave superconductors

    Science.gov (United States)

    Wang, Xiao-Qi; Yi, Guang-Yu; Han, Yu; Jiang, Cui; Gong, Wei-Jiang

    2018-07-01

    We construct one mesoscopic circuit in which one quantum dot couples to one DIII-class topological superconductor and one s-wave superconductor, in addition to its connection with the metallic lead. And then, the Andreev reflection current in the metallic lead is evaluated. It is found that the two kinds of superconductors drive the Andreev reflection in the constructive manner. Next as finite superconducting phase difference is taken into account, the Andreev reflection oscillates in period π/2, and it can be suppressed in the low-energy region if the superconducting phase difference is (n + 1/2) π/2 (n ∈ Integer). Such a result is almost independent of the increase of the intradot Coulomb interaction. Therefore, this structure can assist to realize the manipulation of the Andreev reflection. Also, the result in this work provides useful information for understanding the property of the DIII-class topological superconductor.

  11. Superfluid {sup 3}He, a two-fluid system, with the normal-fluid dynamics dominated by Andreev reflection

    Energy Technology Data Exchange (ETDEWEB)

    Pickett, G. R., E-mail: g.pickett@lancaster.ac.uk [Lancaster University, Department of Physics (United Kingdom)

    2014-12-15

    As a specific offering towards his festschrift, we present a review the various properties of the excitation gas in superfluid {sup 3}He, which depend on Andreev reflection. This phenomenon dominates many of the properties of the normal fluid, especially at the lowest temperatures. We outline the ideas behind this dominance and describe a sample of the many experiments in this system which the operation of Andreev reflection has made possible, from temperature measurement, particle detection, vortex imaging to cosmological analogues.

  12. Dependence of enhanced asymmetry-induced transport on collision frequency

    Science.gov (United States)

    Eggleston, D. L.

    2014-07-01

    A single-particle code with collisional effects is used to study how asymmetry-induced radial transport in a non-neutral plasma depends on collision frequency. For asymmetries of the form ϕ1(r) cos(kz) cos(ωt-lθ), two sources for the transport have been identified: resonant particles and axially trapped particles. The simulation shows that this latter type, which occurs near the radius where ω matches the azimuthal rotation frequency ωR, is usually dominant at low collision frequency ν but becomes negligible at higher ν. This behavior can be understood by noting that axially trapped particles have a lower trapping frequency than resonant particles. In the low ν (banana) regime, the radial oscillations have amplitude Δr ≈ vr/ωT, so axially trapped particles dominate, and the transport may even exceed the resonant particle plateau regime level. As ν increases, collisions start to interrupt the slower axially trapped particle oscillations, while the resonant particles are still in the banana regime, so the axially trapped particle contribution to the transport decreases. At the largest ν values, axially trapped particle transport is negligible and the observed diffusion coefficient matches that given by plateau regime resonant particle theory. Heuristic models based on these considerations give reasonable agreement with the observed scaling laws for the value of the collision frequency where axially trapped particle transport starts to decrease and for the enhancement of the diffusion coefficient produced by axially trapped particles.

  13. Dependence of enhanced asymmetry-induced transport on collision frequency

    International Nuclear Information System (INIS)

    Eggleston, D. L.

    2014-01-01

    A single-particle code with collisional effects is used to study how asymmetry-induced radial transport in a non-neutral plasma depends on collision frequency. For asymmetries of the form ϕ 1 (r) cos(kz) cos(ωt−lθ), two sources for the transport have been identified: resonant particles and axially trapped particles. The simulation shows that this latter type, which occurs near the radius where ω matches the azimuthal rotation frequency ω R , is usually dominant at low collision frequency ν but becomes negligible at higher ν. This behavior can be understood by noting that axially trapped particles have a lower trapping frequency than resonant particles. In the low ν (banana) regime, the radial oscillations have amplitude Δr ≈ v r /ω T , so axially trapped particles dominate, and the transport may even exceed the resonant particle plateau regime level. As ν increases, collisions start to interrupt the slower axially trapped particle oscillations, while the resonant particles are still in the banana regime, so the axially trapped particle contribution to the transport decreases. At the largest ν values, axially trapped particle transport is negligible and the observed diffusion coefficient matches that given by plateau regime resonant particle theory. Heuristic models based on these considerations give reasonable agreement with the observed scaling laws for the value of the collision frequency where axially trapped particle transport starts to decrease and for the enhancement of the diffusion coefficient produced by axially trapped particles

  14. Nonlinearly-enhanced energy transport in many dimensional quantum chaos

    KAUST Repository

    Brambila, D. S.; Fratalocchi, Andrea

    2013-01-01

    By employing a nonlinear quantum kicked rotor model, we investigate the transport of energy in multidimensional quantum chaos. This problem has profound implications in many fields of science ranging from Anderson localization to time reversal of classical and quantum waves. We begin our analysis with a series of parallel numerical simulations, whose results show an unexpected and anomalous behavior. We tackle the problem by a fully analytical approach characterized by Lie groups and solitons theory, demonstrating the existence of a universal, nonlinearly-enhanced diffusion of the energy in the system, which is entirely sustained by soliton waves. Numerical simulations, performed with different models, show a perfect agreement with universal predictions. A realistic experiment is discussed in two dimensional dipolar Bose-Einstein-Condensates (BEC). Besides the obvious implications at the fundamental level, our results show that solitons can form the building block for the realization of new systems for the enhanced transport of matter.

  15. Nonlinearly-enhanced energy transport in many dimensional quantum chaos

    KAUST Repository

    Brambila, D. S.

    2013-08-05

    By employing a nonlinear quantum kicked rotor model, we investigate the transport of energy in multidimensional quantum chaos. This problem has profound implications in many fields of science ranging from Anderson localization to time reversal of classical and quantum waves. We begin our analysis with a series of parallel numerical simulations, whose results show an unexpected and anomalous behavior. We tackle the problem by a fully analytical approach characterized by Lie groups and solitons theory, demonstrating the existence of a universal, nonlinearly-enhanced diffusion of the energy in the system, which is entirely sustained by soliton waves. Numerical simulations, performed with different models, show a perfect agreement with universal predictions. A realistic experiment is discussed in two dimensional dipolar Bose-Einstein-Condensates (BEC). Besides the obvious implications at the fundamental level, our results show that solitons can form the building block for the realization of new systems for the enhanced transport of matter.

  16. Weyl nodes in Andreev spectra of multiterminal Josephson junctions: Chern numbers, conductances, and supercurrents

    Science.gov (United States)

    Xie, Hong-Yi; Vavilov, Maxim G.; Levchenko, Alex

    2018-02-01

    We consider mesoscopic four-terminal Josephson junctions and study emergent topological properties of the Andreev subgap bands. We use symmetry-constrained analysis for Wigner-Dyson classes of scattering matrices to derive band dispersions. When the scattering matrix of the normal region connecting superconducting leads is energy independent, the determinant formula for Andreev spectrum can be reduced to a palindromic equation that admits a complete analytical solution. Band topology manifests with an appearance of the Weyl nodes which serve as monopoles of finite Berry curvature. The corresponding fluxes are quantified by Chern numbers that translate into a quantized nonlocal conductance that we compute explicitly for the time-reversal-symmetric scattering matrix. The topological regime can also be identified by supercurrents as Josephson current-phase relationships exhibit pronounced nonanalytic behavior and discontinuities near Weyl points that can be controllably accessed in experiments.

  17. Full counting statistics of multiple Andreev reflections in incoherent diffusive superconducting junctions

    International Nuclear Information System (INIS)

    Samuelsson, P.

    2007-01-01

    We present a theory for the full distribution of current fluctuations in incoherent diffusive superconducting junctions, subjected to a voltage bias. This theory of full counting statistics of incoherent multiple Andreev reflections is valid for an arbitrary applied voltage. We present a detailed discussion of the properties of the first four cumulants as well as the low and high voltage regimes of the full counting statistics. (orig.)

  18. 78 FR 53790 - Public Forum-Safety Culture: Enhancing Transportation Safety

    Science.gov (United States)

    2013-08-30

    ... NATIONAL TRANSPORTATION SAFETY BOARD Public Forum--Safety Culture: Enhancing Transportation Safety On Tuesday and Wednesday, September 10-11, 2013, the National Transportation Safety Board (NTSB) will convene a forum titled, ``Safety Culture: Enhancing Transportation Safety.'' The forum will begin at 9:00...

  19. Irradiation-enhanced and-induced mass transport

    International Nuclear Information System (INIS)

    Rehn, L.E.

    1989-01-01

    Irradiation can be used to enhance diffusion, that is, to increase the rate at which equilibrium is attained, as well as to induce nonequilibrium changes. The main factors influencing whether irradiation will drive a material toward or away from equilibrium are the initial specimen microstructure and geometry, irradiation temperature, and primary recoil spectrum. This paper summarizes known effects of irradiation temperature and primary recoil spectrum on mass transport during irradiation. In comparison to either electron or heavy-ion irradiation, it is concluded that relatively low-energy, light-ion bombardment at intermediate temperatures offers the greatest potential to enhance the rate at which equilibrium is attained. The greatest departures from equilibrium can be expected from irradiation with similar particles at very low temperatures

  20. Transport analysis of pellet-enhanced ICRH plasma in JET

    International Nuclear Information System (INIS)

    Hammett, G.W.; Colestock, P.L.; Granetz, R.S.; McCune, D.C.; Phillips, C.K.; Schmidt, G.L.; Smithe, D.N.; Kupschus, P.

    1989-01-01

    Performance of JET ICRH heated discharges has been significantly enhanced by using pellet fueling to produce a peaked density target for ICRH. The central T i is observed to increase by up to 80%, central T e by up to 40%, and the neutron rate by up to 400%, over their no-pellet values (which are already in the enhanced 'monster-sawtooth' regime). In this paper we describe the transport analysis of these discharges using the TRANSP code. These results indicate that the thermal diffusivities χ i and χ e are reduced by a factor of ∼2 near the plasma center where the pellets have increased the density gradient. The paper focuses on JET discharge 16211 which is documented more fully in a companion paper. (author) 6 refs., 8 figs

  1. Oxygen transport enhancement by functionalized magnetic nanoparticles (FMP) in bioprocesses

    Science.gov (United States)

    Ataide, Filipe Andre Prata

    The enhancement of fluid properties, namely thermal conductivity and mass diffusivity for a wide range of applications, through the use of nanosized particles' suspensions has been gathering increasing interest in the scientific community. In previous studies, Olle et al. (2006) showed an enhancement in oxygen absorption to aqueous solutions of up to 6-fold through the use of functionalized nanosized magnetic particles with oleic acid coating. Krishnamurthy et al. (2006) showed a remarkable 26-fold enhancement in dye diffusion in water. These two publications are landmarks in mass transfer enhancement in chemical systems through the use of nanoparticles. The central goal of this Ph.D. thesis was to develop functionalized magnetic nanoparticles to enhance oxygen transport in bioprocesses. The experimental protocol for magnetic nanoparticles synthesis and purification adopted in this thesis is a modification of that reported by Olle et al. (2006). This is facilitated by employing twice the quantity of ammonia, added at a slower rate, and by filtering the final nanoparticle solution in a cross-flow filtration modulus against 55 volumes of distilled water. This modification in the protocol resulted in improved magnetic nanoparticles with measurably higher mass transfer enhancement. Magnetic nanoparticles with oleic acid and Hitenol-BC coating were screened for oxygen transfer enhancement, since these particles are relatively inexpensive and easy to synthesize. A glass 0.5-liter reactor was custom manufactured specifically for oxygen transport studies in magnetic nanoparticles suspensions. The reactor geometry, baffles and Rushton impeller are of standard dimensions. Mass transfer tests were conducted through the use of the sulphite oxidation method, applying iodometric back-titration. A 3-factor central composite circumscribed design (CCD) was adopted for design of experiments in order to generate sufficiently informative data to model the effect of magnetic

  2. Natural organic matter to enhance electrokinetic transport of PAH

    Energy Technology Data Exchange (ETDEWEB)

    Suer, P.; Joensson, S.; Allard, B. [Man-Technology-Environment Research Centre, Oerebro Univ. (Sweden)

    2001-07-01

    The remediation of contaminated soil can be enhanced with natural organic matter (NOM) as a complexing agent for pollutants. NOM has both hydrophobic and acidic properties, so that it is charged and thus subject to electroremediation. At the same time many contaminants have a high affinity for organic matter. Organic matter was produced in situ in an electric field or added in solute form. The resulting dissolved organic matter was transported towards the cathode, probably by cationic colloids. Produced dissolved organic matter included high molecular weight molecules near the cathode, at the site of pH buffering. Pyrene and phenanthrene were likewise transported towards the cathode. Movement was small but distinctive in 2-day experiments. Clay influence the soil/water distribution of the PAH but no effect on the total transport could be discerned. The presence of solid organic matter in the soil removed all PAH from the water phase, even though the concentration of organic matter in the water phase was high as well. (orig.)

  3. Quantum-confined nanowires as vehicles for enhanced electrical transport

    International Nuclear Information System (INIS)

    Mohammad, S Noor

    2012-01-01

    Electrical transport in semiconductor nanowires taking quantum confinement and dielectric confinement into account has been studied. A distinctly new route has been employed for the study. The fundamental science underlying the model is based on a relationship between the quantum confinement and the structural disorder of the nanowire surface. The role of surface energy and thermodynamic imbalance in nanowire structural disorder has been described. A model for the diameter dependence of energy bandgap of nanowires has been developed. Ionized impurity scattering, dislocation scattering and acoustic phonon scattering have been taken into account to study carrier mobility. A series of calculations on silicon nanowires show that carrier mobility in nanowires can be greatly enhanced by quantum confinement and dielectric confinement. The electron mobility can, for example, be a factor of 2–10 higher at room temperature than the mobility in a free-standing silicon nanowire. The calculated results agree well with almost all experimental and theoretical results available in the literature. They successfully explain experimental observations not understood before. The model is general and applicable to nanowires from all possible semiconductors. It is perhaps the first physical model highlighting the impact of both quantum confinement and dielectric confinement on carrier transport. It underscores the basic causes of thin, lowly doped nanowires in the temperature range 200 K ≤ T ≤ 500 K yielding very high carrier mobility. It suggests that the scattering by dislocations (stacking faults) can be very detrimental for carrier mobility. (paper)

  4. Andreev Bound States Formation and Quasiparticle Trapping in Quench Dynamics Revealed by Time-Dependent Counting Statistics.

    Science.gov (United States)

    Souto, R Seoane; Martín-Rodero, A; Yeyati, A Levy

    2016-12-23

    We analyze the quantum quench dynamics in the formation of a phase-biased superconducting nanojunction. We find that in the absence of an external relaxation mechanism and for very general conditions the system gets trapped in a metastable state, corresponding to a nonequilibrium population of the Andreev bound states. The use of the time-dependent full counting statistics analysis allows us to extract information on the asymptotic population of even and odd many-body states, demonstrating that a universal behavior, dependent only on the Andreev state energy, is reached in the quantum point contact limit. These results shed light on recent experimental observations on quasiparticle trapping in superconducting atomic contacts.

  5. Enhancing Physician Empathy: Optimizing Learner Potential for Narrative Transportation

    Directory of Open Access Journals (Sweden)

    Casey Hester

    2016-12-01

    Full Text Available This article argues for the pedagogical usefulness of engaging with literary texts in the formal training of physicians and healthcare workers. It suggests that particular “skills” in reading and engaging with narrative are as readily teachable to healthcare students as are skills in reading x-rays or in diagnosing symptoms. It focuses on three phenomena associated with literary (and other forms of narrative – namely, the recognition of characters, vicarious experience, and the experience of fellow feeling – and relates them to three categories in cognitive psychology: Theory of Mind, Narrative Transportation, and Empathy. It presents a survey of empirical studies in cognitive psychology that demonstrates the effectiveness of literary narrative in producing these psychological states, and ends by demonstrating how the teaching of a literary narrative – Bastard Out of Carolina – has enhanced these states in students planning on a career in medicine. Such enhancement, the article suggests, are produced by literary features such as imagery, defamiliarization, and patterned organization on the levels of phonology, semantics, and story structure.

  6. Heat Transport Enhancement of Turbulent Thermal Convection by Inserted Channels

    Science.gov (United States)

    Xia, Ke-Qing; Zhang, Lu

    2017-11-01

    We report an experimental study on the heat transport properties of turbulent Rayleigh Benard Convection (RBC) in a rectangular cell with two types of 3D-printed structures inserted inside. The first one splits the original rectangular cell into 60 identical sub cells whose aspect ratio is 1:1:10 (length, width, height). The second one splits the cell into 30 sub cells, each with a 1:2:10 aspect ratio and a baffle in the center. We find that for large Rayleigh numbers (Ra), the Nusselt numbers (Nu) of both structures increase compared with that of the empty rectangular cell. An enhancement in Nu as much as 20% is found for the second type of insertion at Rayleigh number 2 ×109 . Moreover, the Nu-Ra scaling shows a transition with both geometries. The particle image velocimetry (PIV) measurement within a single sub unit indicates that the transition may be related to the laminar to turbulent transition in flow field. Direct numerical simulations (DNS) confirm the experimental results. Our results demonstrate the potential in using insertions to enhance passive heat transfer. This work was supported by the Research Grants Council (RGC) of HKSAR (Nos. CUHK404513 and CUHK14301115).

  7. Thin porphyrin composite membranes with enhanced organic solvent transport

    KAUST Repository

    Phuoc, Duong

    2018-05-01

    Extending the stability of polymeric membranes in organic solvents is important for applications in chemical and pharmaceutical industry. Thin-film composite membranes with enhanced solvent permeance are proposed, using porphyrin as a building block. Hybrid polyamide films are formed by interfacial polymerization of 5,10,15,20-(tetra-4-aminophenyl)porphyrin/m-phenylene diamine (MPD) mixtures with trimesoyl chloride. Porphyrin is a non-planar molecule, containing a heterocyclic tetrapyrrole unit. Its incorporation into a polyamide film leads to higher free volume than that of a standard polyamide film. Polyamide films derived from porphyrin and MPD amines with a fixed total amine concentration of 1wt% and various porphyrin/MPD ratios were fabricated and characterized. The porphyrin/MPD polyamide film was complexed with Cu(II), due to the binding capacity of porphyrin to metal ions. By coupling scanning transmission electron microscopy (STEM) with electron energy-loss spectroscopy (EELS), Cu mapping was obtained, revealing the distribution of porphyrin in the interfacial polymerized layer. By using porphyrin as amine-functionalized monomer a membrane with thin selective skin and enhanced solvent transport is obtained, with good dye selectivity in the nanofiltration range. For instance, an ultra-fast hexane permeance, 40-fold increased, was confirmed when using 0.5/0.5 porphyrin/MPD mixtures, instead of only MPD as amine monomer. A rejection of 94.2% Brilliant Blue R (826g/mol) in methanol was measured.

  8. 78 FR 59880 - Enhanced Consumer Protections for Charter Air Transportation

    Science.gov (United States)

    2013-09-30

    ... Protections for Charter Air Transportation AGENCY: Office of the Secretary (OST), U.S. Department of... charter air transportation. First, this proposal would require air taxis and commuter air carriers that sell charter air transportation but rely on others to perform that air transportation to make certain...

  9. Unconventional Andreev reflection on the quasi-one-dimensional superconductor Nb2PdxSe5

    Directory of Open Access Journals (Sweden)

    Yeping Jiang

    2016-04-01

    Full Text Available We have carried out Andreev reflection measurements on point contact junctions between normal metal and single crystals of the quasi-one-dimensional (Q1D superconductor Nb2PdxSe5 (Tc ∼ 5.5 K. The contacts of the junctions were made on either self-cleaved surfaces or crystal edges so that the current flow directions in the two types of junctions are different, and the measurements provide a directional probe for the order parameter of the superconductor. Junctions made in both configurations show typical resistances of ∼20-30 Ohms, and a clear double-gap Andreev reflection feature was consistently observed at low temperatures. Quantitative analysis of the conductance spectrum based on a modified Blonder-Tinkham-Klapwijk (BTK model suggests that the amplitudes of two order parameters may have angular dependence in the a-c plane. Moreover, the gap to transition temperature ratio (Δ/TC for the larger gap is substantially higher than the BCS ratio expected for phonon-mediated s-wave superconductors. We argue that the anisotropic superconducting order parameter and the extremely large gap to transition temperature ratio may be associated with an unconventional pairing mechanism in the inorganic Q1D superconductor.

  10. Enhanced cellular transport and drug targeting using dendritic nanostructures

    Science.gov (United States)

    Kannan, R. M.; Kolhe, Parag; Kannan, Sujatha; Lieh-Lai, Mary

    2003-03-01

    Dendrimers and hyperbranched polymers possess highly branched architectures, with a large number of controllable, tailorable, peripheral' functionalities. Since the surface chemistry of these materials can be modified with relative ease, these materials have tremendous potential in targeted drug delivery. The large density of end groups can also be tailored to create enhanced affinity to targeted cells, and can also encapsulate drugs and deliver them in a controlled manner. We are developing tailor-modified dendritic systems for drug delivery. Synthesis, drug/ligand conjugation, in vitro cellular and in vivo drug delivery, and the targeting efficiency to the cell are being studied systematically using a wide variety of experimental tools. Results on PAMAM dendrimers and polyol hyperbranched polymers suggest that: (1) These materials complex/encapsulate a large number of drug molecules and release them at tailorable rates; (2) The drug-dendrimer complex is transported very rapidly through a A549 lung epithelial cancel cell line, compared to free drug, perhaps by endocytosis. The ability of the drug-dendrimer-ligand complexes to target specific asthma and cancer cells is currently being explored using in vitro and in vivo animal models.

  11. Surfactant-enhanced flushing enhances colloid transport and alters macroporosity in diesel-contaminated soil.

    Science.gov (United States)

    Guan, Zhuo; Tang, Xiang-Yu; Nishimura, Taku; Katou, Hidetaka; Liu, Hui-Yun; Qing, Jing

    2018-02-01

    Soil contamination by diesel has been often reported as a result of accidental spillage, leakage and inappropriate use. Surfactant-enhanced soil flushing is a common remediation technique for soils contaminated by hydrophobic organic chemicals. In this study, soil flushing with linear alkylbenzene sulfonates (LAS, an anionic surfactant) was conducted for intact columns (15cm in diameter and 12cm in length) of diesel-contaminated farmland purple soil aged for one year in the field. Dynamics of colloid concentration in column outflow during flushing, diesel removal rate and resulting soil macroporosity change by flushing were analyzed. Removal rate of n-alkanes (representing the diesel) varied with the depth of the topsoil in the range of 14%-96% while the n-alkanes present at low concentrations in the subsoil were completely removed by LAS-enhanced flushing. Much higher colloid concentrations and larger colloid sizes were observed during LAS flushing in column outflow compared to water flushing. The X-ray micro-computed tomography analysis of flushed and unflushed soil cores showed that the proportion of fine macropores (30-250μm in diameter) was reduced significantly by LAS flushing treatment. This phenomenon can be attributed to enhanced clogging of fine macropores by colloids which exhibited higher concentration due to better dispersion by LAS. It can be inferred from this study that the application of LAS-enhanced flushing technique in the purple soil region should be cautious regarding the possibility of rapid colloid-associated contaminant transport via preferential pathways in the subsurface and the clogging of water-conducting soil pores. Copyright © 2017. Published by Elsevier B.V.

  12. Enhanced heat transport in environmental systems using microencapsulated phase change materials

    Science.gov (United States)

    Colvin, D. P.; Mulligan, J. C.; Bryant, Y. G.

    1992-01-01

    A methodology for enhanced heat transport and storage that uses a new two-component fluid mixture consisting of a microencapsulated phase change material (microPCM) for enhanced latent heat transport is outlined. SBIR investigations for NASA, USAF, SDIO, and NSF since 1983 have demonstrated the ability of the two-component microPCM coolants to provide enhancements in heat transport up to 40 times over that of the carrier fluid alone, enhancements of 50 to 100 percent in the heat transfer coefficient, practically isothermal operation when the coolant flow is circulated in an optimal manner, and significant reductions in pump work.

  13. Probing spin-polarized edge state superconductivity by Andreev reflection in in-plane magnetic fields

    Energy Technology Data Exchange (ETDEWEB)

    Reinthaler, Rolf W.; Tkachov, Grigory; Hankiewicz, Ewelina M. [Faculty of Physics and Astrophysics, University of Wuerzburg, Wuerzburg (Germany)

    2015-07-01

    Finding signatures of unconventional superconductivity in Quantum Spin Hall systems is one of the challenges of solid state physics. Here we induce superconductivity in a 3D topological insulator thin film to cause the formation of helical edge states, which are protected against backscattering even in finite magnetic fields. Above a critical in-plane magnetic field, which is much smaller than the critical field of typical superconductors, the quasi-particle gap closes, giving rise to energy-dependent spin polarization. In this regime the spin-polarized edge state superconductivity can be detected by Andreev reflection. We propose measurement setups to experimentally observe the spin-dependent excess current and dI/dV characteristics.

  14. Los Alamos neutral particle transport codes: New and enhanced capabilities

    International Nuclear Information System (INIS)

    Alcouffe, R.E.; Baker, R.S.; Brinkley, F.W.; Clark, B.A.; Koch, K.R.; Marr, D.R.

    1992-01-01

    We present new developments in Los Alamos discrete-ordinates transport codes and introduce THREEDANT, the latest in the series of Los Alamos discrete ordinates transport codes. THREEDANT solves the multigroup, neutral-particle transport equation in X-Y-Z and R-Θ-Z geometries. THREEDANT uses computationally efficient algorithms: Diffusion Synthetic Acceleration (DSA) is used to accelerate the convergence of transport iterations, the DSA solution is accelerated using the multigrid technique. THREEDANT runs on a wide range of computers, from scientific workstations to CRAY supercomputers. The algorithms are highly vectorized on CRAY computers. Recently, the THREEDANT transport algorithm was implemented on the massively parallel CM-2 computer, with performance that is comparable to a single-processor CRAY-YMP We present the results of THREEDANT analysis of test problems

  15. North Dakota wheat transportation knowledge for market enhancement.

    Science.gov (United States)

    2010-07-01

    North Dakota wheat producers are located long distances from major consumer and export markets. Understanding the competitive position of their products is important to focusing efforts for market development and transportation investments. Research ...

  16. Water induced sediment levitation enhances downslope transport on Mars.

    Science.gov (United States)

    Raack, Jan; Conway, Susan J; Herny, Clémence; Balme, Matthew R; Carpy, Sabrina; Patel, Manish R

    2017-10-27

    On Mars, locally warm surface temperatures (~293 K) occur, leading to the possibility of (transient) liquid water on the surface. However, water exposed to the martian atmosphere will boil, and the sediment transport capacity of such unstable water is not well understood. Here, we present laboratory studies of a newly recognized transport mechanism: "levitation" of saturated sediment bodies on a cushion of vapor released by boiling. Sediment transport where this mechanism is active is about nine times greater than without this effect, reducing the amount of water required to transport comparable sediment volumes by nearly an order of magnitude. Our calculations show that the effect of levitation could persist up to ~48 times longer under reduced martian gravity. Sediment levitation must therefore be considered when evaluating the formation of recent and present-day martian mass wasting features, as much less water may be required to form such features than previously thought.

  17. Direct observation of the Andreev reflection of a quasiparticle beam by quantum turbulence in superfluid 3He-B

    International Nuclear Information System (INIS)

    Bradley, D.I.; Fisher, S.N.; Guenault, A.M.; Lowe, M.R.; Pickett, G.R.; Rahm, A.

    2003-01-01

    A beam of quasiparticles from a black-body radiator is directed at a localized region of quantum turbulence generated by a vibrating wire resonator driven at super-critical velocity. We are able to measure directly the fraction of the incident quasiparticle beam which is retro-reflected from the turbulence by Andreev processes. Combining these measurements with previous measurements on the spatial extent of the turbulence may allow us to infer the vortex line density

  18. Gate-voltage control of equal-spin Andreev reflection in half-metal/semiconductor/superconductor junctions

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Xiuqiang, E-mail: xianqiangzhe@126.com [National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093 (China); Meng, Hao, E-mail: menghao1982@shu.edu.cn [School of Physics and Telecommunication Engineering, Shanxi University of Technology, Hanzhong 723001 (China)

    2016-04-22

    With the Blonder–Tinkham–Klapwijk (BTK) approach, we investigate conductance spectrum in Ferromagnet/Semiconductor/Superconductor (FM/Sm/SC) double tunnel junctions where strong Rashba spin–orbit interaction (RSOI) is taken into account in semiconductors. For the half-metal limit, we find that the in-gap conductance becomes finite except at zero voltage when inserting a ferromagnetic insulator (FI) at the Sm/SC interface, which means that the appearance of a long-range triplet states in the half-metal. This is because of the emergence of the unconventional equal-spin Andreev reflection (ESAR). When the FI locates at the FM/Sm interface, however, we find the vanishing in-gap conductance due to the absence of the ESAR. Moreover, the non-zero in-gap conductance shows a nonmonotonic dependence on RSOI which can be controlled by applying an external gate voltage. Our results can be used to generate and manipulate the long-range spin triplet correlation in the nascent field of superconducting spintronics. - Highlights: • We study the equal-spin Andreev reflection in half-metal/semiconductor/superconductor (HM/Sm/SC) junctions. • The equal-spin Andreev reflection appearance when inserting a ferromagnetic insulator at the Sm/SC interface. • The finite in-gap conductance is attributed to the emergence of the equal-spin Andreev reflection. • The finite in-gap conductance shows a nonmonotonic dependence on Rashba spin–orbit interaction. • The finite in-gap conductance can be controlled by applying an external gate voltage.

  19. Enhanced bulk conductivity and bipolar transport in mixtures of MoOx and organic hole transport materials

    International Nuclear Information System (INIS)

    Tian, Baolin; Ban, Dayan; Aziz, Hany

    2013-01-01

    We study the conductivity of thin films of molybdenum oxide (MoO x ) mixed with an organic hole transport material, such as N,N′-bis(naphthalen-1-yl)-N,N′-bis (phenyl)benzidine or 4′,4″-tri(N-carbazolyl)triphenylamine, in lateral test devices. Contrary to previous reports, the conductivity of the mixture is found to exceed that of neat MoO x , exhibiting ∼ 5 orders of magnitude higher conductivity in comparison to the neat films. Studies also show that the mixing enhances both hole and electron transport. The higher conductivity may be attributed to a higher concentration of “free” carriers in the mixture, as a result of the formation of a charge transfer complex between the MoO x and the hole transport material. The findings shed light on the potential of hybrid composites of inorganic and organic materials in realizing enhanced conductivity. - Highlights: • We investigate the conductivity of mixtures of MoO x and hole transport material (HTM). • Materials are studied in lateral devices instead of conventional vertical devices. • Mixing MoO x with HTM brings > 5 orders of magnitude increase in bulk conductivity. • The mixture of MoO x and HTM enhances both hole and electron transport

  20. Enhancement of In Vitro Skin Transport and In Vivo Hypoglycemic ...

    African Journals Online (AJOL)

    ... (PVP) for the enhancement of the transdermal delivery of glimepiride (GMD). Methods: Matrix-type transdermal patches containing GMD, drug coprecipitate ... evaluation of the formulations was conducted using automated diffusion system.

  1. Thin porphyrin composite membranes with enhanced organic solvent transport

    KAUST Repository

    Phuoc, Duong; Anjum, Dalaver H.; Peinemann, Klaus-Viktor; Nunes, Suzana Pereira

    2018-01-01

    Extending the stability of polymeric membranes in organic solvents is important for applications in chemical and pharmaceutical industry. Thin-film composite membranes with enhanced solvent permeance are proposed, using porphyrin as a building block

  2. Theory of the Andreev reflection and the density of states in proximity contact normal-superconducting infinite double-layer

    International Nuclear Information System (INIS)

    Nagato, Yasushi; Nagai, Katsuhiko

    1993-01-01

    Proximity contact N-S double-layer with infinite layer widths is studied in the clean limit. The finite reflection at the interface is taken into account. Starting from a recent theory of finite width double-layer by Ashida et al., the authors obtain explicit expressions for the quasi-classical Green's function which already satisfy the boundary condition and include no exploding terms at infinities. The self-consistent pair potentials are obtained numerically with sufficient accuracy. The Andreev reflection at the N-S interface is discussed on the basis of the self-consistent pair potential. It is shown that there exists a resonance state in a potential valley formed between the depressed pair potential and the partially reflecting interface, which leads to a peak of the Andreev reflection coefficient with the height unity slightly below the bulk superconductor energy gap. They also find general relationship between the Andreev reflection coefficient and the local density of states of the superconductor just at the interface

  3. Enhanced water transport and salt rejection through hydrophobic zeolite pores

    Science.gov (United States)

    Humplik, Thomas; Lee, Jongho; O'Hern, Sean; Laoui, Tahar; Karnik, Rohit; Wang, Evelyn N.

    2017-12-01

    The potential of improvements to reverse osmosis (RO) desalination by incorporating porous nanostructured materials such as zeolites into the selective layer in the membrane has spurred substantial research efforts over the past decade. However, because of the lack of methods to probe transport across these materials, it is still unclear which pore size or internal surface chemistry is optimal for maximizing permeability and salt rejection. We developed a platform to measure the transport of water and salt across a single layer of zeolite crystals, elucidating the effects of internal wettability on water and salt transport through the ≈5.5 Å pores of MFI zeolites. MFI zeolites with a more hydrophobic (i.e., less attractive) internal surface chemistry facilitated an approximately order of magnitude increase in water permeability compared to more hydrophilic MFI zeolites, while simultaneously fully rejecting both potassium and chlorine ions. However, our results also demonstrated approximately two orders of magnitude lower permeability compared to molecular simulations. This decreased performance suggests that additional transport resistances (such as surface barriers, pore collapse or blockages due to contamination) may be limiting the performance of experimental nanostructured membranes. Nevertheless, the inclusion of hydrophobic sub-nanometer pores into the active layer of RO membranes should improve both the water permeability and salt rejection of future RO membranes (Fasano et al 2016 Nat. Commun. 7 12762).

  4. Enhancing Transportation Education Using Mobile Devices and Applications

    Science.gov (United States)

    Gallup, Jennifer; Lamothe, Saron N.; Gallup, Adam

    2015-01-01

    The most salient aspect of independent living and successful post-high school transition to employment is having the ability to independently use transportation. Adolescents and young adults with disabilities continue to experience significantly lower employment rates than their peers without disabilities (Wagner et al., 2003). One way to support…

  5. Enhanced water transport and salt rejection through hydrophobic zeolite pores.

    Science.gov (United States)

    Humplik, Thomas; Lee, Jongho; O'Hern, Sean; Laoui, Tahar; Karnik, Rohit; Wang, Evelyn N

    2017-12-15

    The potential of improvements to reverse osmosis (RO) desalination by incorporating porous nanostructured materials such as zeolites into the selective layer in the membrane has spurred substantial research efforts over the past decade. However, because of the lack of methods to probe transport across these materials, it is still unclear which pore size or internal surface chemistry is optimal for maximizing permeability and salt rejection. We developed a platform to measure the transport of water and salt across a single layer of zeolite crystals, elucidating the effects of internal wettability on water and salt transport through the ≈5.5 Å pores of MFI zeolites. MFI zeolites with a more hydrophobic (i.e., less attractive) internal surface chemistry facilitated an approximately order of magnitude increase in water permeability compared to more hydrophilic MFI zeolites, while simultaneously fully rejecting both potassium and chlorine ions. However, our results also demonstrated approximately two orders of magnitude lower permeability compared to molecular simulations. This decreased performance suggests that additional transport resistances (such as surface barriers, pore collapse or blockages due to contamination) may be limiting the performance of experimental nanostructured membranes. Nevertheless, the inclusion of hydrophobic sub-nanometer pores into the active layer of RO membranes should improve both the water permeability and salt rejection of future RO membranes (Fasano et al 2016 Nat. Commun. 7 12762).

  6. Lifetime-Enhanced Transport in Silicon due to Spin and Valley Blockade

    NARCIS (Netherlands)

    Lansbergen, G.P.; Rahman, R.; Verduijn, J.; Tettamanzi, G.C.; Collaert, N.; Biesemans, S.; Klimeck, G.; Hollenberg, L.C.L.; Rogge, S.

    2011-01-01

    We report the observation of lifetime-enhanced transport (LET) based on perpendicular valleys in silicon by transport spectroscopy measurements of a two-electron system in a silicon transistor. The LET is manifested as a peculiar current step in the stability diagram due to a forbidden transition

  7. Persistent wind-induced enhancement of diffusive CO2 transport in a mountain forest snowpack

    Science.gov (United States)

    D. R. Bowling; W. J. Massman

    2011-01-01

    Diffusion dominates the transport of trace gases between soil and the atmosphere. Pressure gradients induced by atmospheric flow and wind interacting with topographical features cause a small but persistent bulk flow of air within soil or snow. This forcing, called pressure pumping or wind pumping, leads to a poorly quantified enhancement of gas transport beyond the...

  8. Enhanced energy deposition symmetry by hot electron transport

    International Nuclear Information System (INIS)

    Wilson, D.; Mack, J.; Stover, E.; VanHulsteyn, D.; McCall, G.; Hauer, A.

    1981-01-01

    High energy electrons produced by resonance absorption carry the CO 2 laser energy absorbed in a laser fusion pellet. The symmetrization that can be achieved by lateral transport of the hot electrons as they deposit their energy is discussed. A K/sub α/ experiment shows a surprising symmetrization of energy deposition achieved by adding a thin layer of plastic to a copper sphere. Efforts to numerically model this effect are described

  9. Andreev spectroscopy of FeSe{sub x}Te{sub 1−x}

    Energy Technology Data Exchange (ETDEWEB)

    Fujioka, Naoya, E-mail: f-naoya@moegi.waseda.jp; Shirai, Yoshiki; Miyamoto, Yukihiro; Tachibana, Hironori; Matsuda, Azusa

    2015-11-15

    Highlights: • We fabricated FeSe{sub 0.2}Te{sub 0.8}/oxide/Pb and FeSe{sub 0.2}Te{sub 0.8}/Al/Al{sub 2}O{sub 3}/Pb junctions. • These junctions show anomalous conductance spectra and no Josephson current. • These spectra are explained by S/N interface model with extraordinarily gaps. • Except for anomalous gap values, the result is consistent with s+− symmetry. - Abstract: We fabricated two types of junctions on the c-axis plane of FeSe{sub 0.2}Te{sub 0.8} (Fe[Se,Te], T{sub c} ∼ 13 K) crystals. In the superconductor/oxide/superconductor heterojunctions with a Pb film as a counter electrode, we found a large conductance peak centered at 0 V, and a gap-like feature, which has a much higher energy scale than those reported as a gap energy of Fe[Se,Te]. In spite of a large energy scale, their temperature dependence approximately follows a BCS curve, indicating they come from superconductivity of Fe[Se,Te]. Since these structures can be understood as the results of Andreev bound state at the S/N boundary and the interference effect in the normal metal [1], we tried to identify the effect of a normal layer by fabricating Fe[Se,Te]/Al/Al{sub 2}O{sub 3}/Pb junction. Here, we could realize a clean controlled S/N interface and the tunnel junction to investigate electronic properties of the Al slab. We found similar conductance spectra as those junctions without Al layer, giving a support that the anomalous conductance spectra come from the effect of the S/N interface. As expected, the energy scale of the observed features was reduced when the thickness of the normal metal was increased. The absence of Josephson current and the existence of an Andreev bound state may be a signature of the sign-reversal paring in Fe[Se,Te].

  10. Enhancement of In Vitro Skin Transport and In Vivo Hypoglycemic ...

    African Journals Online (AJOL)

    Methods: Matrix-type transdermal patches containing GMD, drug coprecipitate or its inclusion complex ... influence of pH and motility; avoid hepatic first- pass effect; and reduce .... The enhancement factor (EF) was calculated ... Pharmacokinetic evaluation of GMD patches .... comparison of in vivo performance of GMD (2.5.

  11. How could intelligent safety transport systems enhance safety ?

    NARCIS (Netherlands)

    Wiethoff, M. Heijer, T. & Bekiaris, E.

    2017-01-01

    In Europe, many deaths and injured each years are the cost of today's road traffic. Therefore, it is wise to look for possible solutions for enhancing traffic safety. Some Advanced Driver Assistance Systems (ADAS) are expected to increase safety, but they may also evoke new safety hazards. Only

  12. An evolved xylose transporter from Zymomonas mobilis enhances sugar transport in Escherichia coli

    Directory of Open Access Journals (Sweden)

    Zhang Jingqing

    2009-12-01

    Full Text Available Abstract Background Xylose is a second most abundant sugar component of lignocellulose besides glucose. Efficient fermentation of xylose is important for the economics of biomass-based biorefineries. However, sugar mixtures are sequentially consumed in xylose co-fermentation with glucose due to carbon catabolite repression (CCR in microorganisms. As xylose transmembrance transport is one of the steps repressed by CCR, it is therefore of interest to develop a transporter that is less sensitive to the glucose inhibition or CCR. Results The glucose facilitator protein Glf transporter from Zymomonas mobilis, also an efficient transporter for xylose, was chosen as the target transporter for engineering to eliminate glucose inhibition on xylose uptake. The evolution of Glf transporter was carried out with a mixture of glucose and xylose in E. coli. Error-prone PCR and random deletion were employed respectively in two rounds of evolution. Aided by a high-throughput screening assay using xylose analog p-nitrophenyl-β-D-xylopyranoside (pNPX in 96-well plates, a best mutant 2-RD5 was obtained that contains several mutations, and a deletion of 134 residues (about 28% of total residues, or three fewer transmembrane sections (TMSs. It showed a 10.8-fold improvement in terms of pNPX transport activity in the presence of glucose. The fermentation performance results showed that this mutant improved xylose consumption by 42% with M9 minimal medium containing 20 g L-1 xylose only, while with the mixture sugar of xylose and glucose, 28% more glucose was consumed, but no obvious co-utilization of xylose was observed. Further glucose fed-batch experiments suggested that the intracellular metabolism of xylose was repressed by glucose. Conclusions Through random mutagenesis and partial deletion coupled with high-throughput screening, a mutant of the Glf transporter (2-RD5 was obtained that relieved the inhibition of xylose transport by glucose. The fermentation

  13. Surface Andreev Bound States and Odd-Frequency Pairing in Topological Superconductor Junctions

    Science.gov (United States)

    Tanaka, Yukio; Tamura, Shun

    2018-04-01

    In this review, we summarize the achievement of the physics of surface Andreev bound states (SABS) up to now. The route of this activity has started from the physics of SABS of unconventional superconductors where the pair potential has a sign change on the Fermi surface. It has been established that SABS can be regarded as a topological edge state with topological invariant defined in the bulk Hamiltonian. On the other hand, SABS accompanies odd-frequency pairing like spin-triplet s-wave or spin-singlet p-wave. In a spin-triplet superconductor junction, induced odd-frequency pairing can penetrate into a diffusive normal metal (DN) attached to the superconductor. It causes so called anomalous proximity effect where the local density of states of quasiparticle in DN has a zero energy peak. When bulk pairing symmetry is spin-triplet px-wave, the anomalous proximity effect becomes prominent and the zero bias voltage conductance is always quantized independent of the resistance in DN and interface. Finally, we show that the present anomalous proximity effect is realized in an artificial topological superconducting system, where a nanowire with spin-orbit coupling and Zeeman field is put on the conventional spin-singlet s-wave superconductor.

  14. Energy gap in MgB2 superconductor: Andreev reflection studies

    International Nuclear Information System (INIS)

    Aswal, D.K.

    2003-01-01

    To investigate the nature of energy gap in MgB 2 superconductor, we have performed Andreev-reflection studies on MgB 2 / Ag planar junctions. The differential resistance (dV/dI) versus voltage (V) characteristics were recorded as a function of temperature, magnetic field and junction-type. The dV/dI vs V characteristic recorded at low temperature and zero-field for a clean MgB 2 / Ag planar junction exhibited several interesting features, such as, zero bias anomaly, a distinct double-minima, sharp resonance peaks near the energy gap etc. The data, however, could not be explained using Blonder-Tinkham-Klapwijk theory of isotropic superconductor, which indicated that energy gap in MgB 2 is not consistent with the weak-coupling BCS theory. This is further supported by unusual temperature and magnetic field dependence of the tunneling characteristics. The results indicate several possibilities for the energy gap in MgB 2 , such as, an anisotropic energy gap, two-energy or an unconventional gap scenario. (author)

  15. Enhancing of optic phonon contribution in hydrodynamic phonon transport

    Science.gov (United States)

    de Tomas, C.; Cantarero, A.; Lopeandia, A. F.; Alvarez, F. X.

    2015-10-01

    In the framework of the kinetic-collective model of phonon heat transport, we analyze how each range of the phonon frequency spectrum contributes to the total thermal conductivity both in the macro and the nanoscale. For this purpose, we use two case study samples: naturally occurring bulk silicon and a 115 nm of diameter silicon nanowire. We show that the contribution of high-energy phonons (optic branches) is non-negligible only when N-collisions are strongly present. This contribution increases when the effective size of the sample decreases, and it is found to be up to a 10% at room temperature for the 115 nm nanowire, corroborating preliminar ab-initio predictions.

  16. Quantum transport in graphene normal-metal superconductor- normal-metal structures

    Directory of Open Access Journals (Sweden)

    H. Mohammadpour

    2008-06-01

    Full Text Available  We study the transport of electrons in a graphene NSN structure in which two normal regions are connected by a superconducting strip of thickness d. Within Dirac-Bogoliubov-de Gennes equations we describe the transmission through the contact in terms of different scattering processes consisting of quasiparticle cotunneling, local and crossed Andreev reflections. Compared to a fully normal structure we show that the angular dependence of the transmission probability is significantly modified by the presence of superconducting correlations. This modifation can be explained in terms of the interplay between Andreev reflection and Klein tunneling of chiral quasiparticles. We further analyze the energy dependence of the resulting differential conductance of the structure. The subgap differential conductance shows features of Andreev reflection and cotunelling processes, which tends to the values of an NS structure for large ds. Above the gap, the differential conductance shows an oscillatory behavior with energy even at very large ds.

  17. Binding proteins enhance specific uptake rate by increasing the substrate-transporter encounter rate.

    Science.gov (United States)

    Bosdriesz, Evert; Magnúsdóttir, Stefanía; Bruggeman, Frank J; Teusink, Bas; Molenaar, Douwe

    2015-06-01

    Microorganisms rely on binding-protein assisted, active transport systems to scavenge for scarce nutrients. Several advantages of using binding proteins in such uptake systems have been proposed. However, a systematic, rigorous and quantitative analysis of the function of binding proteins is lacking. By combining knowledge of selection pressure and physiochemical constraints, we derive kinetic, thermodynamic, and stoichiometric properties of binding-protein dependent transport systems that enable a maximal import activity per amount of transporter. Under the hypothesis that this maximal specific activity of the transport complex is the selection objective, binding protein concentrations should exceed the concentration of both the scarce nutrient and the transporter. This increases the encounter rate of transporter with loaded binding protein at low substrate concentrations, thereby enhancing the affinity and specific uptake rate. These predictions are experimentally testable, and a number of observations confirm them. © 2015 FEBS.

  18. Flux-based transport enhancement as a plausible unifying mechanism for auxin transport in meristem development.

    Directory of Open Access Journals (Sweden)

    Szymon Stoma

    2008-10-01

    Full Text Available Plants continuously generate new organs through the activity of populations of stem cells called meristems. The shoot apical meristem initiates leaves, flowers, and lateral meristems in highly ordered, spiralled, or whorled patterns via a process called phyllotaxis. It is commonly accepted that the active transport of the plant hormone auxin plays a major role in this process. Current hypotheses propose that cellular hormone transporters of the PIN family would create local auxin maxima at precise positions, which in turn would lead to organ initiation. To explain how auxin transporters could create hormone fluxes to distinct regions within the plant, different concepts have been proposed. A major hypothesis, canalization, proposes that the auxin transporters act by amplifying and stabilizing existing fluxes, which could be initiated, for example, by local diffusion. This convincingly explains the organised auxin fluxes during vein formation, but for the shoot apical meristem a second hypothesis was proposed, where the hormone would be systematically transported towards the areas with the highest concentrations. This implies the coexistence of two radically different mechanisms for PIN allocation in the membrane, one based on flux sensing and the other on local concentration sensing. Because these patterning processes require the interaction of hundreds of cells, it is impossible to estimate on a purely intuitive basis if a particular scenario is plausible or not. Therefore, computational modelling provides a powerful means to test this type of complex hypothesis. Here, using a dedicated computer simulation tool, we show that a flux-based polarization hypothesis is able to explain auxin transport at the shoot meristem as well, thus providing a unifying concept for the control of auxin distribution in the plant. Further experiments are now required to distinguish between flux-based polarization and other hypotheses.

  19. Multifunctional superparamagnetic nanoparticles for enhanced drug transport in cystic fibrosis

    Science.gov (United States)

    Armijo, Leisha M.; Brandt, Yekaterina I.; Rivera, Antonio C.; Cook, Nathaniel C.; Plumley, John B.; Withers, Nathan J.; Kopciuch, Michael; Smolyakov, Gennady A.; Huber, Dale L.; Smyth, Hugh D.; Osinski, Marek

    2012-10-01

    Iron oxide colloidal nanoparticles (ferrofluids) are investigated for application in the treatment of cystic fibrosis lung infections, the leading cause of mortality in cystic fibrosis patients. We investigate the use of iron oxide nanoparticles to increase the effectiveness of administering antibiotics through aerosol inhalation using two mechanisms: directed particle movement in the presence of an inhomogeneous static external magnetic field and magnetic hyperthermia. Magnetic hyperthermia is an effective method for decreasing the viscosity of the mucus and biofilm, thereby enhancing drug, immune cell, and antibody penetration to the affected area. Iron oxide nanoparticles of various sizes and morphologies were synthesized and tested for specific losses (heating power). Nanoparticles in the superparamagnetic to ferromagnetic size range exhibited excellent heating power. Additionally, iron oxide / zinc selenide core/shell nanoparticles were prepared, in order to enable imaging of the iron oxide nanoparticles. We also report on synthesis and characterization of MnSe/ZnSeS alloyed quantum dots.

  20. Reclaimed wastewater quality enhancement by oxygen injection during transportation.

    Science.gov (United States)

    Rodríguez-Gómez, L E; Alvarez, M; Rodríguez-Sevilla, J; Marrero, M C; Hernández, A

    2011-01-01

    In-sewer treatments have been studied in sewer systems, but few have been carried out on reclaimed wastewater systems. A study of oxygen injection has been performed in a completely filled gravity pipe, 0.6 m in diameter and 62 km long, in cast iron with concrete inside coating, which is part of the reclaimed wastewater reuse scheme of Tenerife (Spain). A high pressure oxygen injection system was installed at 16.0 km from pipe inlet and a constant dosage of 30 mg/L O(2) has been injected during six months, under three different operational modes (low COD, 63 mg/L; high COD, 91 mg/L; and partially nitrified water). Oxygen has been consumed in nitrification and organic matter reduction. Generally, nitrification is clearly favored instead of the organic matter oxidation. Nitrification occurs, in general, with nitrite accumulation due to the presence of free ammonia above 1 mg/L. Denitrification is in all cases incomplete due to a limitation of easily biodegradable organic matter content, inhibiting the appearance of anaerobic conditions and sulfide generation. A notable reduction of organic matter parameters is achieved (TSS below 10 mg/L), which is significantly higher than that observed under the ordinary transport conditions without oxygen. This leads to a final cost reduction, and the oxygen injection system helps water reuse managers to maintain a final good water quality in the case of a treatment plant malfunction.

  1. Surface plasmon enhanced quantum transport in a hybrid metal nanoparticle array

    International Nuclear Information System (INIS)

    Sun, Lin; Nan, Yali; Xu, Shang; Zhang, Sishi; Han, Min

    2014-01-01

    Hybrid Pd–Ag nanoparticle arrays composed of randomly distributed Pd nanoparticles in dense packing and a small number of dispersed Ag nanoparticles were fabricated with controlled coverage. Photo-enhanced conductance was observed in the nanoparticle arrays. Largest enhancement, which can be higher than 20 folds, was obtained with 450 nm light illumination. This wavelength was found to correlate with the surface plasmon resonance of the Ag nanoparticles. Electron transport measurements showed there were significant Coulomb blockade in the nanoparticle arrays and the blockade could be overcome with the surface plasmon enhanced local field of Ag nanoparticles induced by light illumination. - Highlights: • We study photo-enhanced electron conductance of a hybrid Pd–Ag nanoparticle array. • The light-induced conductance enhancement is as high as 20 folds at 10 K. • The enhancement is correlate with the surface plasmon resonance of Ag nanoparticles. • Coulomb blockades is overcome with the surface plasmon enhanced local field

  2. Transportation Security : federal action needed to enhance security efforts : statement of Peter Guerrero, Director, Physical Infrastructure Issues

    Science.gov (United States)

    2003-09-09

    Mr. Guerrero's testimony examines (1) challenges in securing the nation's transportation system; (2) actions transportation operators, as well as state and local governments, have taken since September 11 to enhance security; (3) the federal role in ...

  3. Drug-induced GABA transporter currents enhance GABA release to induce opioid withdrawal behaviors.

    Science.gov (United States)

    Bagley, Elena E; Hacker, Jennifer; Chefer, Vladimir I; Mallet, Christophe; McNally, Gavan P; Chieng, Billy C H; Perroud, Julie; Shippenberg, Toni S; Christie, MacDonald J

    2011-10-30

    Neurotransmitter transporters can affect neuronal excitability indirectly via modulation of neurotransmitter concentrations or directly via transporter currents. A physiological or pathophysiological role for transporter currents has not been described. We found that GABA transporter 1 (GAT-1) cation currents directly increased GABAergic neuronal excitability and synaptic GABA release in the periaqueductal gray (PAG) during opioid withdrawal in rodents. In contrast, GAT-1 did not indirectly alter GABA receptor responses via modulation of extracellular GABA concentrations. Notably, we found that GAT-1-induced increases in GABAergic activity contributed to many PAG-mediated signs of opioid withdrawal. Together, these data support the hypothesis that GAT-1 activity directly produces opioid withdrawal signs through direct hyperexcitation of GABAergic PAG neurons and nerve terminals, which presumably enhances GABAergic inhibition of PAG output neurons. These data provide, to the best of our knowledge, the first evidence that dysregulation of a neurotransmitter transporter current is important for the maladaptive plasticity that underlies opiate withdrawal.

  4. Giant Andreev Backscattering through a Quantum Point Contact Coupled via a Disordered Two-Dimensional Electron Gas to Superconductors

    International Nuclear Information System (INIS)

    den Hartog, S.G.; van Wees, B.J.; Klapwijk, T.M.; Nazarov, Y.V.; Borghs, G.

    1997-01-01

    We have investigated the superconducting-phase-modulated reduction in the resistance of a ballistic quantum point contact (QPC) connected via a disordered two-dimensional electron gas (2DEG) to superconductors. We show that this reduction is caused by coherent Andreev backscattering of holes through the QPC, which increases monotonically by reducing the bias voltage to zero. In contrast, the magnitude of the phase-dependent resistance of the disordered 2DEG displays a nonmonotonic reentrant behavior versus bias voltage. copyright 1997 The American Physical Society

  5. Enhancement of transport properties of a Brownian particle due to quantum effects: Smoluchowski limit

    International Nuclear Information System (INIS)

    Shit, Anindita; Chattopadhyay, Sudip; Chaudhuri, Jyotipratim Ray

    2012-01-01

    Graphical abstract: By invoking physically motivated coordinate transformation into quantum Smoluchowski equation, we have presented a transparent treatment for the determination of the effective diffusion coefficient and current of a quantum Brownian particle. Substantial enhancement in the efficiency of the diffusive transport is envisaged due to the quantum correction effects. Highlights:: ► Transport of a quantum Brownian particle in a periodic potential has been addressed. ► Governing quantum Smoluchowski equation (QSE) includes state dependent diffusion. ► A coordinate transformation is used to recast QSE with constant diffusion. ► Transport properties increases in comparison to the corresponding classical result. ► This enhancement is purely a quantum effect. - Abstract: The transport property of a quantum Brownian particle that interacts strongly with a bath (in which a typical damping constant by far exceeds a characteristic frequency of the isolated system) under the influence of a tilted periodic potential has been studied by solving quantum Smoluchowski equation (QSE). By invoking physically motivated coordinate transformation into QSE, we have presented a transparent treatment for the determination of the effective diffusion coefficient of a quantum Brownian particle and the current (the average stationary velocity). Substantial enhancement in the efficiency of the diffusive transport is envisaged due to the quantum correction effects only if the bath temperature hovers around an appropriate range of intermediate values. Our findings also confirm the results obtained in the classical cases.

  6. Enhanced quantum interference transport in gold films with random antidot arrays

    Directory of Open Access Journals (Sweden)

    Zhaoguo Li

    2016-09-01

    Full Text Available We report on the quantum interference transport of randomly distributed antidot arrays, which were prepared on gold films via the focused ion beam direct writing method. The temperature dependence of the gold films’ resistances with and without random antidot arrays were described via electron–phonon interaction theory. Compared with the pristine gold films, we observed an unexpected enhancement of the weak localization signature in the random antidot array films. The physical mechanism behind this enhancement may originate from the enhancement of electron–electron interactions or the suppression of electron–phonon interactions; further evidence is required to determine the exact mechanism.

  7. Webcams, Crowdsourcing, and Enhanced Crosswalks: Developing a Novel Method to Analyze Active Transportation.

    Science.gov (United States)

    Hipp, J Aaron; Manteiga, Alicia; Burgess, Amanda; Stylianou, Abby; Pless, Robert

    2016-01-01

    Active transportation opportunities and infrastructure are an important component of a community's design, livability, and health. Features of the built environment influence active transportation, but objective study of the natural experiment effects of built environment improvements on active transportation is challenging. The purpose of this study was to develop and present a novel method of active transportation research using webcams and crowdsourcing, and to determine if crosswalk enhancement was associated with changes in active transportation rates, including across a variety of weather conditions. The 20,529 publicly available webcam images from two street intersections in Washington, DC, USA were used to examine the impact of an improved crosswalk on active transportation. A crowdsource, Amazon Mechanical Turk, annotated image data. Temperature data were collected from the National Oceanic and Atmospheric Administration, and precipitation data were annotated from images by trained research assistants. Summary analyses demonstrated slight, bi-directional differences in the percent of images with pedestrians and bicyclists captured before and after the enhancement of the crosswalks. Chi-square analyses revealed these changes were not significant. In general, pedestrian presence increased in images captured during moderate temperatures compared to images captured during hot or cold temperatures. Chi-square analyses indicated the crosswalk improvement may have encouraged walking and biking in uncomfortable outdoor conditions (P < 0.5). The methods employed provide an objective, cost-effective alternative to traditional means of examining the effects of built environment changes on active transportation. The use of webcams to collect active transportation data has applications for community policymakers, planners, and health professionals. Future research will work to validate this method in a variety of settings as well as across different built

  8. Webcams, crowdsourcing, and enhanced crosswalks: Developing a novel method to analyze active transportation

    Directory of Open Access Journals (Sweden)

    J. Aaron eHipp

    2016-05-01

    Full Text Available Introduction: Active transportation opportunities and infrastructure are an important component of a community’s design, livability, and health. Features of the built environment influence active transportation, but objective study of the natural experiment effects of built environment improvements on active transportation is challenging. The purpose of this study was to develop and present a novel method of active transportation research using webcams and crowdsourcing, and to determine if crosswalk enhancement was associated with changes in active transportation rates, including across a variety of weather conditions. Methods: 20,529 publicly available webcam images from two street intersections in Washington, D.C., were used to examine the impact of an improved crosswalk on active transportation. A crowdsource, Amazon Mechanical Turk, annotated image data. Temperature data was collected from the National Oceanic and Atmospheric Administration, and precipitation data was annotated from images by trained research assistants. Results: Summary analyses demonstrated slight, bi-directional differences in the percent of images with pedestrians and bicyclists captured before and after the enhancement of the crosswalks. Chi-square analyses revealed these changes were not significant. In general, pedestrian presence increased in images captured during moderate temperatures compared to images captured during hot or cold temperatures. Chi-square analyses indicated the crosswalk improvement may have encouraged walking and biking in uncomfortable outdoor conditions (p<0.5. Conclusion: The methods employed provide an objective, cost-effective alternative to traditional means of examining the effects of built environment changes on active transportation. The use of webcams to collect active transportation data has applications for community policymakers, planners, and health professionals. Future research will work to validate this method in a variety of

  9. Nanoscale radiation transport and clinical beam modeling for gold nanoparticle dose enhanced radiotherapy (GNPT) using X-rays.

    Science.gov (United States)

    Zygmanski, Piotr; Sajo, Erno

    2016-01-01

    We review radiation transport and clinical beam modelling for gold nanoparticle dose-enhanced radiotherapy using X-rays. We focus on the nanoscale radiation transport and its relation to macroscopic dosimetry for monoenergetic and clinical beams. Among other aspects, we discuss Monte Carlo and deterministic methods and their applications to predicting dose enhancement using various metrics.

  10. Enhancing electron transport in Si:P delta-doped devices by rapid thermal anneal

    International Nuclear Information System (INIS)

    Goh, K. E. J.; Augarten, Y.; Oberbeck, L.; Simmons, M. Y.

    2008-01-01

    We address the use of rapid thermal anneal (RTA) to enhance electron mobility and phase coherent transport in Si:P δ-doped devices encapsulated by low temperature Si molecular beam epitaxy while minimizing dopant diffusion. RTA temperatures of 500-700 deg. C were applied to δ-doped layers encapsulated at 250 deg. C. From 4.2 K magnetotransport measurements, we find that the improved crystal quality after RTA increases the mobility/mean free path by ∼40% and the phase coherence length by ∼25%. Our results suggest that the initial capping layer has near optimal crystal quality and transport improvement achieved by a RTA is limited

  11. Carrier Transport Enhancement in Conjugated Polymers through Interfacial Self-Assembly of Solution-State Aggregates

    KAUST Repository

    Zhao, Kui

    2016-07-13

    We demonstrate that local and long range orders of poly(3-hexylthiophene) (P3HT) semicrystalline films can be synergistically improved by combining chemical functionalization of the dielectric surface with solution-state disentanglement and pre-aggregation of P3HT in a theta solvent, leading to a very significant enhancement of the field effect carrier mobility. The pre-aggregation and surface functionalization effects combine to enhance the carrier mobility nearly 100-fold as compared with standard film preparation by spin-coating, and nearly 10-fold increase over the benefits of pre-aggregation alone. In situ quartz crystal microbalance with dissipation (QCM-D) experiments reveal enhanced deposition of pre-aggregates on surfaces modified with an alkyl-terminated self-assembled monolayer (SAM) in comparison to un-aggregated polymer chains. Additional investigations reveal the combined pre-aggregation and surface functionalization significantly enhances local order of the conjugated polymer through planarization and extension of the conjugated backbone of the polymer which clearly translate to significant improvements of carrier transport at the semiconductor-dielectric interface in organic thin film transistors. This study points to opportunities in combining complementary routes, such as well-known pre-aggregation with substrate chemical functionalization, to enhance the polymer self-assembly and improve its interfacial order with benefits for transport properties.

  12. Inhibition or knockdown of ABC transporters enhances susceptibility of adult and juvenile schistosomes to Praziquantel.

    Directory of Open Access Journals (Sweden)

    Ravi S Kasinathan

    2014-10-01

    parasite ABC multidrug transporters might serve as important targets for enhancing the action of PZQ. They also suggest a potentially novel and readily-available strategy for overcoming reduced PZQ susceptibility of schistosomes.

  13. Nonlinear 2D convection and enhanced cross-field plasma transport near the MHD instability threshold

    International Nuclear Information System (INIS)

    Pastukhov, V.P.; Chudin, N.V.

    2003-01-01

    Results of theoretical study and computer simulations of nonlinear 2D convection induced by a convective MHD instability near its threshold in FRC-like non-paraxial magnetic confinement system are presented. An appropriate closed set of weakly nonideal reduced MHD equations is derived to describe the self-consistent plasma dynamics. It is shown that the convection forms nonlinear large scale stochastic vortices (convective cells), which tend to restore and to maintain the marginally stable pressure pro e and result in an essentially nonlocal enhanced heat transport. A large amount of data on the structure of the nascent convective flows is obtained and analyzed. The computer simulations of long time plasma evolutions demonstrate such features of the resulting anomalous transport as pro e consistency, L-H transition, external transport barrier, pinch of impurities, etc. (author)

  14. Heat transport in the XXZ spin chain: from ballistic to diffusive regimes and dephasing enhancement

    International Nuclear Information System (INIS)

    Mendoza-Arenas, J J; Al-Assam, S; Clark, S R; Jaksch, D

    2013-01-01

    In this work we study the heat transport in an XXZ spin-1/2 Heisenberg chain with homogeneous magnetic field, incoherently driven out of equilibrium by reservoirs at the boundaries. We focus on the effect of bulk dephasing (energy-dissipative) processes in different parameter regimes of the system. The non-equilibrium steady state of the chain is obtained by simulating its evolution under the corresponding Lindblad master equation, using the time evolving block decimation method. In the absence of dephasing, the heat transport is ballistic for weak interactions, while being diffusive in the strongly interacting regime, as evidenced by the heat current scaling with the system size. When bulk dephasing takes place in the system, diffusive transport is induced in the weakly interacting regime, with the heat current monotonically decreasing with the dephasing rate. In contrast, in the strongly interacting regime, the heat current can be significantly enhanced by dephasing for systems of small size. (paper)

  15. Glutamate transporter activity promotes enhanced Na+/K+-ATPase -mediated extracellular K+ management during neuronal activity

    DEFF Research Database (Denmark)

    Larsen, Brian R; Holm, Rikke; Vilsen, Bente

    2016-01-01

    , in addition, Na+ /K+ -ATPase-mediated K+ clearance could be governed by astrocytic [Na+ ]i . During most neuronal activity, glutamate is released in the synaptic cleft and is re-absorbed by astrocytic Na+ -coupled glutamate transporters, thereby elevating [Na+ ]i . It thus remains unresolved whether...... the different Na+ /K+ -ATPase isoforms are controlled by [K+ ]o or [Na+ ]i during neuronal activity. Hippocampal slice recordings of stimulus-induced [K+ ]o transients with ion-sensitive microelectrodes revealed reduced Na+ /K+ -ATPase-mediated K+ management upon parallel inhibition of the glutamate transporter......+ affinity to the α1 and α2 isoforms than the β2 isoform. In summary, enhanced astrocytic Na+ /K+ -ATPase-dependent K+ clearance was obtained with parallel glutamate transport activity. The astrocytic Na+ /K+ -ATPase isoform constellation α2β1 appeared to be specifically geared to respond to the [Na+ ]i...

  16. Reactive Transport Modeling of Microbe-mediated Fe (II) Oxidation for Enhanced Oil Recovery

    Science.gov (United States)

    Surasani, V.; Li, L.

    2011-12-01

    Microbially Enhanced Oil Recovery (MEOR) aims to improve the recovery of entrapped heavy oil in depleted reservoirs using microbe-based technology. Reservoir ecosystems often contain diverse microbial communities those can interact with subsurface fluids and minerals through a network of nutrients and energy fluxes. Microbe-mediated reactions products include gases, biosurfactants, biopolymers those can alter the properties of oil and interfacial interactions between oil, brine, and rocks. In addition, the produced biomass and mineral precipitates can change the reservoir permeability profile and increase sweeping efficiency. Under subsurface conditions, the injection of nitrate and Fe (II) as the electron acceptor and donor allows bacteria to grow. The reaction products include minerals such as Fe(OH)3 and nitrogen containing gases. These reaction products can have large impact on oil and reservoir properties and can enhance the recovery of trapped oil. This work aims to understand the Fe(II) oxidation by nitrate under conditions relevant to MEOR. Reactive transport modeling is used to simulate the fluid flow, transport, and reactions involved in this process. Here we developed a complex reactive network for microbial mediated nitrate-dependent Fe (II) oxidation that involves both thermodynamic controlled aqueous reactions and kinetic controlled Fe (II) mineral reaction. Reactive transport modeling is used to understand and quantify the coupling between flow, transport, and reaction processes. Our results identify key parameter controls those are important for the alteration of permeability profile under field conditions.

  17. Enhancing the design of in situ chemical barriers with multicomponent reactive transport modeling

    International Nuclear Information System (INIS)

    Sevougian, S.D.; Steefel, C.I.; Yabusaki, S.B.

    1994-11-01

    This paper addresses the need for systematic control of field-scale performance in the emplacement and operation of in situ chemical treatment barriers; in particular, it addresses the issue of how the local coupling of reaction kinetics and material heterogeneities at the laboratory or bench scale can be accurately upscaled to the field. The authors have recently developed modeling analysis tools that can explicitly account for all relevant chemical reactions that accompany the transport of reagents and contaminants through a chemically and physically heterogeneous subsurface rock or soil matrix. These tools are incorporated into an enhanced design methodology for in situ chemical treatment technologies, and the new methodology is demonstrated in the ongoing design of a field experiment for the In Situ Redox Manipulation (ISRM) project at the U.S. Department of Energy (DOE) Hanford Site. The ISRM design approach, which systematically integrates bench-scale and site characterization information, provides an ideal test for the new reactive transport techniques. The need for the enhanced chemistry capability is demonstrated by an example that shows how intra-aqueous redox kinetics can affect the transport of reactive solutes. Simulations are carried out on massively parallel computer architectures to resolve the influence of multiscale heterogeneities on multicomponent, multidimensional reactive transport. The technology will soon be available to design larger-scale remediation schemes

  18. Amplified CPEs enhancement of chorioamnion membrane mass transport by encapsulation in nano-sized PLGA particles.

    Science.gov (United States)

    Azagury, Aharon; Amar-Lewis, Eliz; Appel, Reut; Hallak, Mordechai; Kost, Joseph

    2017-08-01

    Chemical penetration enhancers (CPEs) have long been used for mass transport enhancement across membranes. Many CPEs are used in a solution or gel and could be a solvent. The use of CPEs is mainly limited due to their toxicity/irritation levels. This study presents the evaluation of encapsulated CPEs in nano-sized polymeric particles on the chorioamnion (CA) membrane mass transport. CPEs' mass encapsulated in nanoparticles was decreased by 10,000-fold. Interestingly, this approach resulted in a 6-fold increase in mass transport across the CA. This approach may also be used with other CPEs' base applications necessitating lower CPE concentration. Applying Ultrasound (US) has shown to increase the release rate of and also the mass transport across the CA membrane. It is proposed that encapsulated CPEs penetrate into the CA membrane thus prolonging their exposure, possibly extending their penetration into the CA membrane, while insonation also deepens their penetration into the CA membrane. Copyright © 2017 Elsevier B.V. All rights reserved.

  19. Enhancement in transport properties of seeded melt-textured YBCO by Cu-site doping

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Yu X. [Department of Physics, Hong Kong Baptist University, Kowloon (China); Texas Center for Superconductivity and Department of Mechanical Engineering, University of Houston, Houston, TX (United States); Lo, W.; Salama, Kamel [Texas Center for Superconductivity and Department of Mechanical Engineering, University of Houston, Houston, TX (United States); Tang, Tong B. [Department of Physics, Hong Kong Baptist University, Kowloon (China)

    2002-05-01

    A significant research effort has been made worldwide to introduce nanometre-scale weak superconducting regions into seeded melt-textured superconductors to enhance their critical current density, trapped magnetic field and levitation force. The enhancement in these properties is dependent on the pinning forces exerted on the magnetic flux lines. In this paper we present a substantial improvement in the transport properties of these materials by optimizing the fabrication conditions, controlling the oxygen deficiency, as well as adjusting the doping level of Zn in YBa{sub 2}(Cu{sub 1-x}Zn{sub x}){sub 3}O{sub 7-}{delta} large grains. The enhancement is found to be as much as 30% by doping between about x=0.001 25 and 0.002 53. The results strongly indicate that the introduction of local nanometre-scale weak superconducting regions by Zn substitution for Cu in the CuO{sub 2} plane enhances the transport properties. Due to the simplicity of the processing conditions, these doping techniques can have a significant potential for a variety of engineering applications. (author)

  20. Carbon materials for enhancing charge transport in the advancements of perovskite solar cells

    Science.gov (United States)

    Hu, Ruiyuan; Chu, Liang; Zhang, Jian; Li, Xing'ao; Huang, Wei

    2017-09-01

    Organic-inorganic halide perovskite solar cells (PSCs) have become a new favorite in the photovoltaic field, due to the boosted efficiency up to 22.1%. Despite a flow of achievements, there are certain challenges to simultaneously meet high efficiency, large scale, low cost and high stability. Due to the low cost, extensive sources, high electrical conductivity and chemical stability, carbon materials have made undeniable contributions to play positive roles in developing PSCs. Carbon materials not only have the favorable conductivity but also bipolar advantage, which can transfer both electrons and holes. In this review, we will discuss how the carbon materials transfer charge or accelerate charge transport by incorporation in PSCs. Carbon materials can replace transparent conductive oxide layers, and enhance electron transport in electron transport layers. Moreover, carbon materials with continuous structure, especially carbon nanotubes and graphene, can provide direct charge transport channel that make them suitable additives or even substitutes in hole transport layers. Especially, the successful application of carbon materials as counter electrodes makes the devices full-printable, low temperature and high stability. Finally, a brief outlook is provided on the future development of carbon materials for PSCs, which are expected to devote more contributions in the future photovoltaic market.

  1. Transport through hybrid superconducting/normal nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Futterer, David

    2013-01-29

    We mainly investigate transport through interacting quantum dots proximized by superconductors. For this purpose we extend an existing theory to describe transport through proximized quantum dots coupled to normal and superconducting leads. It allows us to study the influence of a strong Coulomb interaction on Andreev currents and Josephson currents. This is a particularly interesting topic because it combines two competing properties: in superconductors Cooper pairs are formed by two electrons which experience an attractive interaction while two electrons located on a quantum dot repel each other due to the Coulomb interaction. It seems at first glance that transport processes involving Cooper pairs should be suppressed because of the two competing interactions. However, it is possible to proximize the dot in nonequilibrium situations. At first, we study a setup composed of a quantum dot coupled to one normal, one ferromagnetic, and one superconducting lead in the limit of an infinitely-large superconducting gap. Within this limit the coupling between dot and superconductor is described exactly by the presented theory. It leads to the formation of Andreev-bound states (ABS) and an additional bias scheme opens in which a pure spin current, i.e. a spin current with a vanishing associated charge current, can be generated. In a second work, starting from the infinite-gap limit, we perform a systematic expansion of the superconducting gap around infinity and investigate Andreev currents and Josephson currents. This allows us to estimate the validity of infinite-gap calculations for real systems in which the superconducting gap is usually a rather small quantity. We find indications that a finite gap renormalizes the ABS and propose a resummation approach to explore the finite-gap ABS. Despite the renormalization effects the modifications of transport by finite gaps are rather small. This result lets us conclude that the infinite-gap calculation is a valuable tool to

  2. Transport through hybrid superconducting/normal nanostructures

    International Nuclear Information System (INIS)

    Futterer, David

    2013-01-01

    We mainly investigate transport through interacting quantum dots proximized by superconductors. For this purpose we extend an existing theory to describe transport through proximized quantum dots coupled to normal and superconducting leads. It allows us to study the influence of a strong Coulomb interaction on Andreev currents and Josephson currents. This is a particularly interesting topic because it combines two competing properties: in superconductors Cooper pairs are formed by two electrons which experience an attractive interaction while two electrons located on a quantum dot repel each other due to the Coulomb interaction. It seems at first glance that transport processes involving Cooper pairs should be suppressed because of the two competing interactions. However, it is possible to proximize the dot in nonequilibrium situations. At first, we study a setup composed of a quantum dot coupled to one normal, one ferromagnetic, and one superconducting lead in the limit of an infinitely-large superconducting gap. Within this limit the coupling between dot and superconductor is described exactly by the presented theory. It leads to the formation of Andreev-bound states (ABS) and an additional bias scheme opens in which a pure spin current, i.e. a spin current with a vanishing associated charge current, can be generated. In a second work, starting from the infinite-gap limit, we perform a systematic expansion of the superconducting gap around infinity and investigate Andreev currents and Josephson currents. This allows us to estimate the validity of infinite-gap calculations for real systems in which the superconducting gap is usually a rather small quantity. We find indications that a finite gap renormalizes the ABS and propose a resummation approach to explore the finite-gap ABS. Despite the renormalization effects the modifications of transport by finite gaps are rather small. This result lets us conclude that the infinite-gap calculation is a valuable tool to

  3. Mass transport enhancement in redox flow batteries with corrugated fluidic networks

    Science.gov (United States)

    Lisboa, Kleber Marques; Marschewski, Julian; Ebejer, Neil; Ruch, Patrick; Cotta, Renato Machado; Michel, Bruno; Poulikakos, Dimos

    2017-08-01

    We propose a facile, novel concept of mass transfer enhancement in flow batteries based on electrolyte guidance in rationally designed corrugated channel systems. The proposed fluidic networks employ periodic throttling of the flow to optimally deflect the electrolytes into the porous electrode, targeting enhancement of the electrolyte-electrode interaction. Theoretical analysis is conducted with channels in the form of trapezoidal waves, confirming and detailing the mass transport enhancement mechanism. In dilute concentration experiments with an alkaline quinone redox chemistry, a scaling of the limiting current with Re0.74 is identified, which compares favourably against the Re0.33 scaling typical of diffusion-limited laminar processes. Experimental IR-corrected polarization curves are presented for high concentration conditions, and a significant performance improvement is observed with the narrowing of the nozzles. The adverse effects of periodic throttling on the pumping power are compared with the benefits in terms of power density, and an improvement of up to 102% in net power density is obtained in comparison with the flow-by case employing straight parallel channels. The proposed novel concept of corrugated fluidic networks comes with facile fabrication and contributes to the improvement of the transport characteristics and overall performance of redox flow battery systems.

  4. Atrial Natriuretic Peptide Stimulates Dopamine Tubular Transport by Organic Cation Transporters: A Novel Mechanism to Enhance Renal Sodium Excretion

    Science.gov (United States)

    Kouyoumdzian, Nicolás M.; Rukavina Mikusic, Natalia L.; Kravetz, María C.; Lee, Brenda M.; Carranza, Andrea; Del Mauro, Julieta S.; Pandolfo, Marcela; Gironacci, Mariela M.; Gorzalczany, Susana; Toblli, Jorge E.; Fernández, Belisario E.

    2016-01-01

    The aim of this study was to demonstrate the effects of atrial natriuretic peptide (ANP) on organic cation transporters (OCTs) expression and activity, and its consequences on dopamine urinary levels, Na+, K+-ATPase activity and renal function. Male Sprague Dawley rats were infused with isotonic saline solution during 120 minutes and randomized in nine different groups: control, pargyline plus tolcapone (P+T), ANP, dopamine (DA), D-22, DA+D-22, ANP+D-22, ANP+DA and ANP+DA+D-22. Renal functional parameters were determined and urinary dopamine concentration was quantified by HPLC. Expression of OCTs and D1-receptor in membrane preparations from renal cortex tissues were determined by western blot and Na+, K+-ATPase activity was determined using in vitro enzyme assay. 3H-DA renal uptake was determined in vitro. Compared to P+T group, ANP and dopamine infusion increased diuresis, urinary sodium and dopamine excretion significantly. These effects were more pronounced in ANP+DA group and reversed by OCTs blockade by D-22, demonstrating that OCTs are implied in ANP stimulated-DA uptake and transport in renal tissues. The activity of Na+, K+-ATPase exhibited a similar fashion when it was measured in the same experimental groups. Although OCTs and D1-receptor protein expression were not modified by ANP, OCTs-dependent-dopamine tubular uptake was increased by ANP through activation of NPR-A receptor and protein kinase G as signaling pathway. This effect was reflected by an increase in urinary dopamine excretion, natriuresis, diuresis and decreased Na+, K+-ATPase activity. OCTs represent a novel target that links the activity of ANP and dopamine together in a common mechanism to enhance their natriuretic and diuretic effects. PMID:27392042

  5. Enhanced transport currents in Cu-sheathed MgB{sub 2} wires

    Energy Technology Data Exchange (ETDEWEB)

    Eisterer, M; Weber, H W [Atomic Institute of the Austrian Universities, Vienna (Austria); Glowacki, B A [Department of Materials Science and Metallurgy, University of Cambridge, Cambridge (United Kingdom); Pacific Northwest National Laboratory, Richland, WA (United States); Greenwood, L R [Pacific Northwest National Laboratory, Richland, WA (United States); Majoros, M [Interdisciplinary Research Centre in Superconductivity, University of Cambridge, Cambridge (United Kingdom)

    2002-07-01

    Copper-sheathed MgB{sub 2} wires, prepared by an in-situ process, were exposed to neutron radiation in order to introduce defects into the superconductor. The high level of disorder (4.6x10{sup -2} dpa) leads to a decrease of the transition temperature by more than 4 K, but to an increase of the slope of the irreversibility line, thus resulting in higher irreversibility fields at low temperatures. The transport currents are significantly enhanced at 4.2 K for fields above 2 T. (author)

  6. Glutamine deprivation enhances antitumor activity of 3-bromopyruvate through the stabilization of monocarboxylate transporter-1.

    Science.gov (United States)

    Cardaci, Simone; Rizza, Salvatore; Filomeni, Giuseppe; Bernardini, Roberta; Bertocchi, Fabio; Mattei, Maurizio; Paci, Maurizio; Rotilio, Giuseppe; Ciriolo, Maria Rosa

    2012-09-01

    Anticancer drug efficacy might be leveraged by strategies to target certain biochemical adaptations of tumors. Here we show how depriving cancer cells of glutamine can enhance the anticancer properties of 3-bromopyruvate, a halogenated analog of pyruvic acid. Glutamine deprival potentiated 3-bromopyruvate chemotherapy by increasing the stability of the monocarboxylate transporter-1, an effect that sensitized cells to metabolic oxidative stress and autophagic cell death. We further elucidated mechanisms through which resistance to chemopotentiation by glutamine deprival could be circumvented. Overall, our findings offer a preclinical proof-of-concept for how to employ 3-bromopyruvate or other monocarboxylic-based drugs to sensitize tumors to chemotherapy. ©2012 AACR.

  7. Enhanced ionic transport in fine-grained scandia-stabilized zirconia ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Abdala, Paula M.; Lamas, Diego G. [CINSO (Centro de Investigaciones en Solidos), CONICET-CITEFA, J.B. de La Salle 4397 (B1603ALO) Villa Martelli, Pcia. de Buenos Aires (Argentina); Custo, Graciela S. [Gerencia de Area Seguridad Nuclear y Ambiente, Gerencia Quimica, Departamento Quimica Analitica, Centro Atomico Constituyentes, Comision Nacional de Energia Atomica, Av. Constituyentes 1499 (B1650KNA) San Martin, Pcia. de Buenos Aires (Argentina)

    2010-06-01

    In this work, the transport properties of fine-grained scandia-stabilized zirconia ceramics with low Si content have been investigated. These materials were prepared from ZrO{sub 2}-6 mol% Sc{sub 2}O{sub 3} nanopowders synthesized by a nitrate-lysine gel-combustion route. High relative densities and excellent electrical properties were obtained, even for sintering temperatures as low as 1350 C. Our electrochemical impedance spectroscopy study showed that both the volume fraction of grain boundaries and the specific grain-boundary conductivity are significantly enhanced with decreasing grain size, resulting in a higher total ionic conductivity. (author)

  8. The role of polymer dots on efficiency enhancement of organic solar cells: Improving charge transport property

    Science.gov (United States)

    Li, Jinfeng; Zhang, Xinyuan; Liu, Chunyu; Li, Zhiqi; He, Yeyuan; Zhang, Zhihui; Shen, Liang; Guo, Wenbin; Ruan, Shengping

    2017-07-01

    In this work, poly(9,9-dioctylfluorene)-co-(4,7-di-2-thienyl-2,1,3-benzothiadiazole) (PF-5DTBT) and copolymer poly(styrene-co-maleic anhydride) (PSMA) dots were prepared as additive for active layer doping to enhance the power conversion efficiency (PCE) of organic solar cells (OSCs), which based on poly[N-9″-hepta-decanyl-2,7-carbazole-alt-5,5-(4‧,7‧-di-2-thienyl-2‧,1‧,3‧-benzothiadiazole) (PCDTBT) and [6,6]-phenyl C71 butyric acid methyl-ester (PC71BM). A high efficiency of 7.40% was achieved due to increase of short-circuit current (Jsc) and fill factor (FF). The operation mechanism of OSCs doping with polymer dots was investigated, which demonstrated that the efficiency enhancement ascribes to improvement of electrical properties, such as exciton generation, exction dissociation, charge transport, and charge collection.

  9. 14C/C measurements support Andreev's internode method to determine lichen growth rates in Cladina stygia (Fr.) Ahti

    Energy Technology Data Exchange (ETDEWEB)

    Holt, E; Bench, G

    2007-12-05

    Growth rates and the ability to date an organism can greatly contribute to understanding its population biology and community dynamics. 1n 1954, Andreev proposed a method to date Cladina, a fruticose lichen, using total thallus length and number of internodes. No research, however, has demonstrated the reliability of this technique or compared its estimates to those derived by other means. In this study, we demonstrate the utility of {sup 14}C/C ratios to determine lichen age and growth rate in Cladina stygia (Fr.) Ahti collected from northwestern Alaska, USA. The average growth rate using {sup 14}C/C ratios was 6.5 mm {center_dot} yr{sup -1}, which was not significantly different from growth rates derived by Andreev's internode method (average = 6.2 mm {center_dot} yr{sup -1}); thus, suggesting the reliability of Andreev's simple field method for dating lichens. In addition, we found lichen growth rates appeared to differ with geographic location, yet did not seem related to ambient temperature and total precipitation.

  10. Surfactant-Enhanced Size-Excluded Transport of Bacteria Through Unsaturated Porous Media.

    Science.gov (United States)

    Zhu, J.

    2017-12-01

    US domestic waste water is rich in surfactants because of the intensive usage of surfactants-containing household product. It results in a surfactants presence environment when this untreated waste water released into subsurface. It was reported that surfactants enhance the colloidal transport in porous media, which have significant effect on issues such as subsurface pathogens contamination and biodegradation. In this study, soil column experiments were conducted. The soil column was remained unsaturated and with a steady flow passing through it. Escherichia coli K-12 transported in the soil column and its breakthrough data was collected in presence of surfactant anionic surfactant linear alkylbenzene sulfonate (LAS) concentration range over 0, 0.25, 0.5, 0.75, 1, and 2 times Critical Micelle Concentration (CMC). It was found that the increase in LAS concentration greatly increases breakthrough concentration C/C0 and decreases breakthrough time tb until LAS concentration reaches 1 xCMC. Numerical models were built simulating and investigating this phenomenon. The goodness of model fitting was greatly improved by adding exclusion factor into the model, which indicated that the presence of surfactant might enhance the exclusion effect. The relationships between LAS concentration and the two coefficients, deposition rate coefficient k and exclusion effect coefficient θim, were found can be fitted by a quasi-Langmuir equation. And the model validation with observed data showed that the model has an acceptable reliability.

  11. Helium transport and exhaust studies in enhanced confinement regimes in DIII-D

    International Nuclear Information System (INIS)

    Wade, M.R.; Hillis, D.L.; Hogan, J.T.; Mahdavi, M.A.; Maingi, R.; West, W.P.; Burrell, K.H.; Finkenthal, D.F.; Gohil, P.; Groebner, R.J.

    1995-02-01

    A better understanding of helium transport in the plasma core and edge in enhanced confinement regimes is now emerging from recent experimental studies on DIII-D. Overall, the results are encouraging. Significant helium exhaust (τ* He /τ E ∼ 11) has been obtained in a diverted, ELMing H-mode plasma simultaneous with a central source of helium. Detailed analysis of the helium profile evolution indicates that the exhaust rate is limited by the exhaust efficiency of the pump (∼5%) and not by the intrinsic helium transport properties of the plasma. Perturbative helium transport studies using gas puffing have shown that D He /X eff ∼1 in all confinement regimes studied to date (including H-mode and VH-mode). Furthermore, there is no evidence of preferential accumulation of helium in any of these regimes. However, measurements in the core and pumping plenum show a significant dilution of helium as it flows from the plasma core to the pumping plenum. Such dilution could be the limiting factor in the overall removal rate of helium in a reactor system

  12. Copper Complexes with Tetradentate Ligands for Enhanced Charge Transport in Dye-Sensitized Solar Cells

    Directory of Open Access Journals (Sweden)

    Hannes Michaels

    2018-05-01

    Full Text Available In dye-sensitized solar cells (DSCs, the redox mediator is responsible for the regeneration of the oxidized dye and for the hole transport towards the cathode. Here, we introduce new copper complexes with tetradentate 6,6′-bis(4-(S-isopropyl-2-oxazolinyl-2,2′-bipyridine ligands, Cu(oxabpy, as redox mediators. Copper coordination complexes with a square-planar geometry show low reorganization energies and thus introduce smaller losses in photovoltage. Slow recombination kinetics of excited electrons between the TiO2 and CuII(oxabpy species lead to an exceptionally long electron lifetime, a high Fermi level in the TiO2, and a high photovoltage of 920 mV with photocurrents of 10 mA∙cm−2 and 6.2% power conversion efficiency. Meanwhile, a large driving force remains for the dye regeneration of the Y123 dye with high efficiencies. The square-planar Cu(oxabpy complexes yield viscous gel-like solutions. The unique charge transport characteristics are attributed to a superposition of diffusion and electronic conduction. An enhancement in charge transport performance of 70% despite the higher viscosity is observed upon comparison of Cu(oxabpy to the previously reported Cu(tmby2 redox electrolyte.

  13. Dopant controlled trap-filling and conductivity enhancement in an electron-transport polymer

    Energy Technology Data Exchange (ETDEWEB)

    Higgins, Andrew, E-mail: aehiggin@princeton.edu, E-mail: kahn@princeton.edu; Kahn, Antoine, E-mail: aehiggin@princeton.edu, E-mail: kahn@princeton.edu [Department of Electrical Engineering, Princeton University, Princeton, New Jersey 08544-5263 (United States); Mohapatra, Swagat K.; Barlow, Stephen; Marder, Seth R. [Center for Organic Photonics and Electronics and School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30332-0400 (United States)

    2015-04-20

    Charge transport in organic semiconductors is often inhibited by the presence of tail states that extend into the band gap of a material and act as traps for charge carriers. This work demonstrates the passivation of acceptor tail states by solution processing of ultra-low concentrations of a strongly reducing air-stable organometallic dimer, the pentamethylrhodocene dimer, [RhCp*Cp]{sub 2}, into the electron transport polymer poly([N,N′-bis(2-octyldodecyl)-naphthalene-1,4,5,8-bis(dicarboximide) -2,6-diyl]-alt-5,5′-(2,2′-bithiophene)), P(NDI{sub 2}OD-T{sub 2}). Variable-temperature current-voltage measurements of n-doped P(NDI{sub 2}OD-T{sub 2}) are presented with doping concentration varied through two orders of magnitude. Systematic variation of the doping parameter is shown to lower the activation energy for hopping transport and enhance film conductivity and electron mobility.

  14. Facile synthesis of mesostructured ZSM-5 zeolite with enhanced mass transport and catalytic performances

    Energy Technology Data Exchange (ETDEWEB)

    Li, Chao; Ren, Yanqun [School of Chemistry and Chemical Engineering, South China University of Technology, 381 Wushan Road, Tianhe District, Guangzhou 510641 (China); Gou, Jinsheng [College Material Science and Technology, Beijing Forestry University, Key Laboratory of Wooden Material Science and Application, Ministry of Education, 35 Tsinghua East Road, Haidian District, Beijing 100083 (China); Liu, Baoyu [School of Chemistry and Chemical Engineering, South China University of Technology, 381 Wushan Road, Tianhe District, Guangzhou 510641 (China); Xi, Hongxia, E-mail: cehxxi@scut.edu.cn [School of Chemistry and Chemical Engineering, South China University of Technology, 381 Wushan Road, Tianhe District, Guangzhou 510641 (China)

    2017-01-15

    Highlights: • A mesostructured MFI zeolite was synthesized via dual-functional surfactant approach. • Mass transport was investigated by applying zero length column technique. • The catalyst exhibited excellent catalytic activity and long lifetime. • Gaussian DFT was employed to study the role of surfactant in crystallization process. - Abstract: A mesostructured ZSM-5 zeolite with multilamellar structure was successfully synthesized by employing a tetra-headgroup rigid bolaform quaternary ammonium surfactant. It was characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM), nitrogen adsorption/desorption isotherms, amines temperature programmed desorption (amines-TPD), and computer simulation. These results indicated that the dual-functional amphiphilic surfactants play a critical role for directing the multilamellar structure with high mesoporosity. The mass transport and catalytic performances of the zeolite were investigated by zero length column (ZLC) technique and aldol condensation reactions to evaluate the structure-property relationship. These results clearly indicated that the mass transport of selected molecules in hierarchical zeolite can be accelerated by introducing mesoporous structure with mesostructure with reduced diffusion length and an overall enhanced resistance against deactivation in reactions involving large molecules. Furthermore, the dual-functional surfactant approach of making hierarchical zeolite with MFI nanosheets framework would open up new opportunities for design and synthesis of hierarchical zeolites with controllable mesoporous structures.

  15. Cationic amino acid transporter 2 enhances innate immunity during Helicobacter pylori infection.

    Directory of Open Access Journals (Sweden)

    Daniel P Barry

    Full Text Available Once acquired, Helicobacter pylori infection is lifelong due to an inadequate innate and adaptive immune response. Our previous studies indicate that interactions among the various pathways of arginine metabolism in the host are critical determinants of outcomes following infection. Cationic amino acid transporter 2 (CAT2 is essential for transport of L-arginine (L-Arg into monocytic immune cells during H. pylori infection. Once within the cell, this amino acid is utilized by opposing pathways that lead to elaboration of either bactericidal nitric oxide (NO produced from inducible NO synthase (iNOS, or hydrogen peroxide, which causes macrophage apoptosis, via arginase and the polyamine pathway. Because of its central role in controlling L-Arg availability in macrophages, we investigated the importance of CAT2 in vivo during H. pylori infection. CAT2(-/- mice infected for 4 months exhibited decreased gastritis and increased levels of colonization compared to wild type mice. We observed suppression of gastric macrophage levels, macrophage expression of iNOS, dendritic cell activation, and expression of granulocyte-colony stimulating factor in CAT2(-/- mice suggesting that CAT2 is involved in enhancing the innate immune response. In addition, cytokine expression in CAT2(-/- mice was altered from an antimicrobial Th1 response to a Th2 response, indicating that the transporter has downstream effects on adaptive immunity as well. These findings demonstrate that CAT2 is an important regulator of the immune response during H. pylori infection.

  16. Facile synthesis of mesostructured ZSM-5 zeolite with enhanced mass transport and catalytic performances

    International Nuclear Information System (INIS)

    Li, Chao; Ren, Yanqun; Gou, Jinsheng; Liu, Baoyu; Xi, Hongxia

    2017-01-01

    Highlights: • A mesostructured MFI zeolite was synthesized via dual-functional surfactant approach. • Mass transport was investigated by applying zero length column technique. • The catalyst exhibited excellent catalytic activity and long lifetime. • Gaussian DFT was employed to study the role of surfactant in crystallization process. - Abstract: A mesostructured ZSM-5 zeolite with multilamellar structure was successfully synthesized by employing a tetra-headgroup rigid bolaform quaternary ammonium surfactant. It was characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM), nitrogen adsorption/desorption isotherms, amines temperature programmed desorption (amines-TPD), and computer simulation. These results indicated that the dual-functional amphiphilic surfactants play a critical role for directing the multilamellar structure with high mesoporosity. The mass transport and catalytic performances of the zeolite were investigated by zero length column (ZLC) technique and aldol condensation reactions to evaluate the structure-property relationship. These results clearly indicated that the mass transport of selected molecules in hierarchical zeolite can be accelerated by introducing mesoporous structure with mesostructure with reduced diffusion length and an overall enhanced resistance against deactivation in reactions involving large molecules. Furthermore, the dual-functional surfactant approach of making hierarchical zeolite with MFI nanosheets framework would open up new opportunities for design and synthesis of hierarchical zeolites with controllable mesoporous structures.

  17. Transepithelial Transport of Curcumin in Caco-2 Cells Is significantly Enhanced by Micellar Solubilisation.

    Science.gov (United States)

    Frank, Jan; Schiborr, Christina; Kocher, Alexa; Meins, Jürgen; Behnam, Dariush; Schubert-Zsilavecz, Manfred; Abdel-Tawab, Mona

    2017-03-01

    Curcumin, the active constituent of Curcuma longa L. (family Zingiberaceae), has gained increasing interest because of its anti-cancer, anti-inflammatory, anti-diabetic, and anti-rheumatic properties associated with good tolerability and safety up to very high doses of 12 g. Nanoscaled micellar formulations on the base of Tween 80 represent a promising strategy to overcome its low oral bioavailability. We therefore aimed to investigate the uptake and transepithelial transport of native curcumin (CUR) vs. a nanoscaled micellar formulation (Sol-CUR) in a Caco-2 cell model. Sol-CUR afforded a higher flux than CUR (39.23 vs. 4.98 μg min -1  cm -2 , respectively). This resulted in a higher P app value of 2.11 × 10 -6  cm/s for Sol-CUR compared to a P app value of 0.56 × 10 -6  cm/s for CUR. Accordingly a nearly 9.5 fold higher amount of curcumin was detected on the basolateral side at the end of the transport experiments after 180 min with Sol-CUR compared to CUR. The determined 3.8-fold improvement in the permeability of curcumin is in agreement with an up to 185-fold increase in the AUC of curcumin observed in humans following the oral administration of the nanoscaled micellar formulation compared to native curcumin. The present study demonstrates that the enhanced oral bioavailability of micellar curcumin formulations is likely a result of enhanced absorption into and increased transport through small intestinal epithelial cells.

  18. Enhanced Boron Tolerance in Plants Mediated by Bidirectional Transport Through Plasma Membrane Intrinsic Proteins.

    Science.gov (United States)

    Mosa, Kareem A; Kumar, Kundan; Chhikara, Sudesh; Musante, Craig; White, Jason C; Dhankher, Om Parkash

    2016-02-23

    High boron (B) concentration is toxic to plants that limit plant productivity. Recent studies have shown the involvement of the members of major intrinsic protein (MIP) family in controlling B transport. Here, we have provided experimental evidences showing the bidirectional transport activity of rice OsPIP1;3 and OsPIP2;6. Boron transport ability of OsPIP1;3 and OsPIP2;6 were displayed in yeast HD9 mutant strain (∆fps1∆acr3∆ycf1) as a result of increased B sensitivity, influx and accumulation by OsPIP1;3, and rapid efflux activity by OsPIP2;6. RT-PCR analysis showed strong upregulation of OsPIP1;3 and OsPIP2;6 transcripts in roots by B toxicity. Transgenic Arabidopsis lines overexpressing OsPIP1;3 and OsPIP2;6 exhibited enhanced tolerance to B toxicity. Furthermore, B concentration was significantly increased after 2 and 3 hours of tracer boron ((10)B) treatment. Interestingly, a rapid efflux of (10)B from the roots of the transgenic plants was observed within 1 h of (10)B treatment. Boron tolerance in OsPIP1;3 and OsPIP2;6 lines was inhibited by aquaporin inhibitors, silver nitrate and sodium azide. Our data proved that OsPIP1;3 and OsPIP2;6 are indeed involved in both influx and efflux of boron transport. Manipulation of these PIPs could be highly useful in improving B tolerance in crops grown in high B containing soils.

  19. Caveolin-1 enhances resveratrol-mediated cytotoxicity and transport in a hepatocellular carcinoma model

    Directory of Open Access Journals (Sweden)

    Yang Hui-ling

    2009-03-01

    Full Text Available Abstract Background Resveratrol (RES, an estrogen analog, is considered as a potential cancer chemo-preventive agent. However, it remains unclear how RES is transported into cells. In this study, we observed that Caveolin-1(CAV1 expression can increase the cytotoxic and pro-apoptotic activity of RES in a dose- and time-dependent manner both in vitro and in vivo in a Hepatocellular Carcinoma animal model. Methods High performance liquid chromatography (HPLC demonstrated that RES intra-cellular concentration is increased about 2-fold in cells stably expressing CAV1 or CAVM1 (a scaffolding domain (81-101AA-defective CAV1 mutant compared to the untransduced human Hepatoblastoma cell line (HepG2 or after transduction with the green fluorescent protein (GFP control vector. The increased intra-cellular transport of RES was abolished in cells stably expressing CAVM2 (a cholesterol shuttle domain (143-156AA-defective CAV1 mutant or CAVRNAi. In order to further characterize CAV1-dependent RES transport, we synthesized RES-dansyl chloride derivatives as fluorescent probes to visualize the transport process, which demonstrated a distribution consistent with that of CAV1 in HepG2 cells. Results In addition, RES endocytosis was not mediated by estrogen receptor (ER α and β, as suggested by lack of competitive inhibition by estrogen or Tamoxifen. Pathway analysis showed that RES can up-regulate the expression of endogenous CAV1; this activates further the MAPK pathway and caspase-3 expression. Discussion This study provides novel insights about the role played by CAV1 in modulating cellular sensitivity to RES through enhancement of its internalization and trafficking.

  20. Enhanced neuronal glucose transporter expression reveals metabolic choice in a HD Drosophila model.

    Science.gov (United States)

    Besson, Marie Thérèse; Alegría, Karin; Garrido-Gerter, Pamela; Barros, Luis Felipe; Liévens, Jean-Charles

    2015-01-01

    Huntington's disease is a neurodegenerative disorder caused by toxic insertions of polyglutamine residues in the Huntingtin protein and characterized by progressive deterioration of cognitive and motor functions. Altered brain glucose metabolism has long been suggested and a possible link has been proposed in HD. However, the precise function of glucose transporters was not yet determined. Here, we report the effects of the specifically-neuronal human glucose transporter expression in neurons of a Drosophila model carrying the exon 1 of the human huntingtin gene with 93 glutamine repeats (HQ93). We demonstrated that overexpression of the human glucose transporter in neurons ameliorated significantly the status of HD flies by increasing their lifespan, reducing their locomotor deficits and rescuing eye neurodegeneration. Then, we investigated whether increasing the major pathways of glucose catabolism, glycolysis and pentose-phosphate pathway (PPP) impacts HD. To mimic increased glycolytic flux, we overexpressed phosphofructokinase (PFK) which catalyzes an irreversible step in glycolysis. Overexpression of PFK did not affect HQ93 fly survival, but protected from photoreceptor loss. Overexpression of glucose-6-phosphate dehydrogenase (G6PD), the key enzyme of the PPP, extended significantly the lifespan of HD flies and rescued eye neurodegeneration. Since G6PD is able to synthesize NADPH involved in cell survival by maintenance of the redox state, we showed that tolerance to experimental oxidative stress was enhanced in flies co-expressing HQ93 and G6PD. Additionally overexpressions of hGluT3, G6PD or PFK were able to circumvent mitochondrial deficits induced by specific silencing of genes necessary for mitochondrial homeostasis. Our study confirms the involvement of bioenergetic deficits in HD course; they can be rescued by specific expression of a glucose transporter in neurons. Finally, the PPP and, to a lesser extent, the glycolysis seem to mediate the hGluT3

  1. Enhanced neuronal glucose transporter expression reveals metabolic choice in a HD Drosophila model.

    Directory of Open Access Journals (Sweden)

    Marie Thérèse Besson

    Full Text Available Huntington's disease is a neurodegenerative disorder caused by toxic insertions of polyglutamine residues in the Huntingtin protein and characterized by progressive deterioration of cognitive and motor functions. Altered brain glucose metabolism has long been suggested and a possible link has been proposed in HD. However, the precise function of glucose transporters was not yet determined. Here, we report the effects of the specifically-neuronal human glucose transporter expression in neurons of a Drosophila model carrying the exon 1 of the human huntingtin gene with 93 glutamine repeats (HQ93. We demonstrated that overexpression of the human glucose transporter in neurons ameliorated significantly the status of HD flies by increasing their lifespan, reducing their locomotor deficits and rescuing eye neurodegeneration. Then, we investigated whether increasing the major pathways of glucose catabolism, glycolysis and pentose-phosphate pathway (PPP impacts HD. To mimic increased glycolytic flux, we overexpressed phosphofructokinase (PFK which catalyzes an irreversible step in glycolysis. Overexpression of PFK did not affect HQ93 fly survival, but protected from photoreceptor loss. Overexpression of glucose-6-phosphate dehydrogenase (G6PD, the key enzyme of the PPP, extended significantly the lifespan of HD flies and rescued eye neurodegeneration. Since G6PD is able to synthesize NADPH involved in cell survival by maintenance of the redox state, we showed that tolerance to experimental oxidative stress was enhanced in flies co-expressing HQ93 and G6PD. Additionally overexpressions of hGluT3, G6PD or PFK were able to circumvent mitochondrial deficits induced by specific silencing of genes necessary for mitochondrial homeostasis. Our study confirms the involvement of bioenergetic deficits in HD course; they can be rescued by specific expression of a glucose transporter in neurons. Finally, the PPP and, to a lesser extent, the glycolysis seem to

  2. Coherent diffusive transport mediated by Andreev reflections at V=Delta/e in a mesoscopic superconductor/semiconductor/superconductor junction

    DEFF Research Database (Denmark)

    Kutchinsky, Jonatan; Taboryski, Rafael Jozef; Kuhn, Oliver

    1997-01-01

    We present experiments revealing a singularity in the coherent current across a superconductor/semiconductor/superconductor (SSmS) junction at the bias voltage corresponding to the superconducting energy gap V=Delta/e. The SSmS structure consists of highly doped GaAs with superconducting electrodes...

  3. Coherent diffusive transport mediated by Andreev reflections at V=Δ/e in a mesoscopic superconductor/semiconductor/superconductor junction

    International Nuclear Information System (INIS)

    Kutchinsky, J.; Taboryski, R.; Kuhn, O.; So/rensen, C.B.; Lindelof, P.E.; Kristensen, A.; Hansen, J.B.; Jacobsen, C.S.; Skov, J.L.

    1997-01-01

    We present experiments revealing a singularity in the coherent current across a superconductor/semiconductor/superconductor (SSmS) junction at the bias voltage corresponding to the superconducting energy gap V=Δ/e. The SSmS structure consists of highly doped GaAs with superconducting electrodes of aluminum configured as an interferometer. The phase-coherent component of the current is probed as the amplitude of h/2e vs magnetic-field oscillations in the differential resistance of the interferometer. copyright 1997 The American Physical Society

  4. Transport activity of the sodium bicarbonate cotransporter NBCe1 is enhanced by different isoforms of carbonic anhydrase.

    Directory of Open Access Journals (Sweden)

    Christina Schueler

    Full Text Available Transport metabolons have been discussed between carbonic anhydrase II (CAII and several membrane transporters. We have now studied different CA isoforms, expressed in Xenopus oocytes alone and together with the electrogenic sodium bicarbonate cotransporter 1 (NBCe1, to determine their catalytic activity and their ability to enhance NBCe1 transport activity. pH measurements in intact oocytes indicated similar activity of CAI, CAII and CAIII, while in vitro CAIII had no measurable activity and CAI only 30% of the activity of CAII. All three CA isoforms increased transport activity of NBCe1, as measured by the transport current and the rate of intracellular sodium rise in oocytes. Two CAII mutants, altered in their intramolecular proton pathway, CAII-H64A and CAII-Y7F, showed significant catalytic activity and also enhanced NBCe1 transport activity. The effect of CAI, CAII, and CAII mutants on NBCe1 activity could be reversed by blocking CA activity with ethoxyzolamide (EZA, 10 µM, while the effect of the less EZA-sensitive CAIII was not reversed. Our results indicate that different CA isoforms and mutants, even if they show little enzymatic activity in vitro, may display significant catalytic activity in intact cells, and that the ability of CA to enhance NBCe1 transport appears to depend primarily on its catalytic activity.

  5. Intradot spin-flip Andreev reflection tunneling through a ferromagnet-quantum dot-superconductor system with ac field

    International Nuclear Information System (INIS)

    Song Hongyan; Zhou Shiping

    2008-01-01

    We investigate Andreev reflection (AR) tunneling through a ferromagnet-quantum dot-superconductor (F-QD-S) system in the presence of an external ac field. The intradot spin-flip scattering in the QD is involved. Using the nonequilibrium Green function and BCS quasiparticle spectrum for superconductor, time-averaged AR conductance is formulated. The competition between the intradot spin-flip scattering and photon-assisted tunneling dominates the resonant behaviors of the time-averaged AR conductance. For weak intradot spin-flip scattering strengths, the AR conductance shows a series of equal interval resonant levels. However, the single-peak at main resonant level develops into a well-resolved double-peak resonance at a strong intradot spin-flip scattering strength. Remarkable, multiple-photon-assisted tunneling that generates photonic sideband peaks with a variable interval has been found. In addition, the AR conductance-bias voltage characteristic shows a transition between the single-peak to double-peak resonance as the ratio of the two tunneling strengths varies

  6. Detection and control of broken symmetries with Andreev bound state tunneling spectroscopy: effects of atomic-scale disorder

    International Nuclear Information System (INIS)

    Greene, L.H.; Hentges, P.J.; Aubin, H.; Aprili, M.; Badica, E.; Covington, M.; Pafford, M.M.; Westwood, G.; Klemperer, W.G.; Jian, Sha; Hinks, D.G.

    2004-01-01

    Quasiparticle planar tunneling spectroscopy is used to study unconventional superconductivity in YBa 2 Cu 3 O 7 (YBCO) thin films and Bi 2 Sr 2 CaCu 2 O 8 (BSCCO) single crystals. Tunneling conductances are obtained as a function of crystallographic orientation, applied magnetic field (magnitude and orientation), atomic substitution and surface damage. Our systematic studies confirm that the observed zero-bias conductance peak (ZBCP), a measure of the near-surface quasiparticle (QP) density of states (DoS), is comprised of Andreev bound states (ABS) resulting directly from the sign change of the d-wave order parameter (OP) at the Fermi surface. Our data, plus a literature search, reveals a consistency in the observation of the splitting of the ZBCP in optimally-doped materials. We note that the splitting of the ZBCP observed in applied field, and the spontaneous splitting observed at lower temperatures in zero field, occur concomitantly in a given junction, and that observation of this splitting is dependent upon two parameters: (1) the magnitude of the tunneling cone and (2) the degree of atomic-scale disorder at the interface

  7. DEVELOPMENT OF MICROORGANISMS WITH IMPROVED TRANSPORT AND BIOSURFACTANT ACTIVITY FOR ENHANCED OIL RECOVERY

    Energy Technology Data Exchange (ETDEWEB)

    M.J. McInerney; N. Youssef; T. Fincher; S.K. Maudgalya; M.J. Folmsbee; R. Knapp; D. Nagle

    2004-05-31

    Diverse microorganisms were screened for biosurfactant production and anaerobic growth at elevated salt concentrations to obtain candidates most suitable for microbial oil recovery. Seventy percent of the 205 strains tested, mostly strains of Bacillus mojavensis, Bacillus subtilis, Bacillus licheniformis, and Bacillus sonorensis, produced biosurfactants aerobically and 41% of the strains had biosurfactant activity greater than Bacillus mojavensis JF-2, the current candidate for oil recovery. Biosurfactant activity varied with the percentage of the 3-hydroxy-tetradecanoate isomers in the fatty acid portion of the biosurfactant. Changing the medium composition by incorporation of different precursors of 3-hydroxy tetradecanoate increased the activity of biosurfactant. The surface tension and critical micelle concentration of 15 different, biosurfactant-producing Bacillus strains was determined individually and in combination with other biosurfactants. Some biosurfactant mixtures were found to have synergistic effect on surface tension (e.g. surface tension was lowered from 41 to 31 mN/m in some cases) while others had a synergistic effect on CMD-1 values. We compared the transport abilities of spores from three Bacillus strains using a model porous system to study spore recovery and transport. Sand-packed columns were used to select for spores or cells with the best transport abilities through brine-saturated sand. Spores of Bacillus mojavensis strains JF-2 and ROB-2 and a natural recombinant, strain C-9, transported through sand at very high efficiencies. The earliest cells/spores that emerged from the column were re-grown, allowed to sporulate, and applied to a second column. This procedure greatly enhanced the transport of strain C-9. Spores with enhanced transport abilities can be easily obtained and that the preparation of inocula for use in MEOR is feasible. Tertiary oil recovery experiments showed that 10 to 40 mg/l of JF-2 biosurfactant in the presence of 0

  8. [Monocarboxylate transporter 1 enhances the sensitivity of breast cancer cells to 3-bromopyruvate in vitro].

    Science.gov (United States)

    Li, Qi-Xiang; Zhang, Pei; Liu, Fang; Wang, Xian-Zhi; Li, Lu; Wang, Zhong-Kun; Jiang, Chen-Chen; Zheng, Hai-Lun; Liu, Hao

    2017-05-20

    To investigate the role of monocarboxylate transporter 1 (MCT1) in enhancing the sensitivity of breast cancer cells to 3-bromopyruvate (3-BrPA). The inhibitory effect of 3-BrPA on the proliferation of breast cancer cells was assessed with MTT assay, and brominated propidium bromide single staining flow cytometry was used for detecting the cell apoptosis. An ELISA kit was used to detect the intracellular levels of hexokinase II, lactate dehydrogenase, lactate, and adenosine triphosphate, and Western blotting was performed to detect the expression of MCT1. MDA-MB-231 cells were transiently transfected with MCT1 cDNA for over-expressing MCT1, and the effect of 3-BrPA on the cell proliferation and adenosine triphosphate level was deteced. 3-BrPA did not produce significant effects on the proliferation and apoptosis of MDA-MB-231 cells, and the cells treated with 200 µmol/L 3-BrPA for 24 h showed an inhibition rate and an apoptosis rate of only 8.72% and 7.8%, respectively. The same treatment, however, produced an inhibition rate and an apoptosis rate of 84.6% and 82.3% in MCF-7 cells, respectively. In MDA-MB-231 cells with MCT1 overexpression, 200 µmol/L 3-BrPA resulted in an inhibition rate of 72.44%, significantly higher than that in the control cells (P<0.05); treatment of the cells with 25, 50, 100, and 200 µmol/L 3-BrPA for 6 h resulted in intracellular adenosine triphosphate levels of 96.98%, 88.44%, 43.3% and 27.56% relative to the control level respectively. MCT1 can enhance the sensitivity of breast cancer cells to 3-BrPA possibly by transporting 3-BrPA into cells to inhibit cell glycolysis.

  9. Electrical transport properties of graphene nanowalls grown at low temperature using plasma enhanced chemical vapor deposition

    Science.gov (United States)

    Zhao, Rong; Ahktar, Meysam; Alruqi, Adel; Dharmasena, Ruchira; Jasinski, Jacek B.; Thantirige, Rukshan M.; Sumanasekera, Gamini U.

    2017-05-01

    In this work, we report the electrical transport properties of uniform and vertically oriented graphene (graphene nanowalls) directly synthesized on multiple substrates including glass, Si/SiO2 wafers, and copper foils using radio-frequency plasma enhanced chemical vapor deposition (PECVD) with methane (CH4) as the precursor at relatively low temperatures. The temperature for optimum growth was established with the aid of transmission electron microscopy, scanning electron microscopy, and Raman spectroscopy. This approach offers means for low-cost graphene nanowalls growth on an arbitrary substrate with the added advantage of transfer-free device fabrication. The temperature dependence of the electrical transport properties (resistivity and thermopower) were studied in the temperature range, 30-300 K and analyzed with a combination of 2D-variable range hopping (VRH) and thermally activated (TA) conduction mechanisms. An anomalous temperature dependence of the thermopower was observed for all the samples and explained with a combination of a diffusion term having a linear temperature dependence plus a term with an inverse temperature dependence.

  10. Butyrate transcriptionally enhances peptide transporter PepT1 expression and activity.

    Directory of Open Access Journals (Sweden)

    Guillaume Dalmasso

    Full Text Available BACKGROUND: PepT1, an intestinal epithelial apical di/tripeptide transporter, is normally expressed in the small intestine and induced in colon during chronic inflammation. This study aimed at investigating PepT1 regulation by butyrate, a short-chain fatty acid produced by commensal bacteria and accumulated inside inflamed colonocyte. RESULTS: We found that butyrate treatment of human intestinal epithelial Caco2-BBE cells increased human PepT1 (hPepT1 promoter activity in a dose- and time-dependent manner, with maximal activity observed in cells treated with 5 mM butyrate for 24 h. Under this condition, hPepT1 promoter activity, mRNA and protein expression levels were increased as assessed by luciferase assay, real-time RT-PCR and Western blot, respectively. hPepT1 transport activity was accordingly increased by approximately 2.5-fold. Butyrate did not alter hPepT1 mRNA half-life indicating that butyrate acts at the transcriptional level. Molecular analyses revealed that Cdx2 is the most important transcription factor for butyrate-induced increase of hPepT1 expression and activity in Caco2-BBE cells. Butyrate-activated Cdx2 binding to hPepT1 promoter was confirmed by gel shift and chromatin immunoprecipitation. Moreover, Caco2-BBE cells overexpressing Cdx2 exhibited greater hPepT1 expression level than wild-type cells. Finally, treatment of mice with 5 mM butyrate added to drinking water for 24 h increased colonic PepT1 mRNA and protein expression levels, as well as enhanced PepT1 transport activity in colonic apical membranes vesicles. CONCLUSIONS: Collectively, our results demonstrate that butyrate increases PepT1 expression and activity in colonic epithelial cells, which provides a new understanding of PepT1 regulation during chronic inflammation.

  11. Vacuolar iron transporter BnMEB2 is involved in enhancing iron tolerance of Brassica napus

    Directory of Open Access Journals (Sweden)

    Wei Zhu

    2016-09-01

    Full Text Available Iron toxicity is a major nutrient disorder that severely affects crop development and yield. Vacuolar detoxification of metal stress is an important strategy for plants to survive and adapt to this adverse environment. Vacuolar iron transporter (VIT members are involved in this process and play essential roles in iron storage and transport. In this study, a rapeseed VIT gene BnMEB2 (BnaC07g30170D was identified. BnMEB2 is a homolog to Arabidopsis MEB2 (At5g24290 and acts as a detoxifier in vacuolar sequestration of divalent metal. Transient expression analysis revealed that BnMEB2 was localized to the vacuolar membrane. Q-PCR detection showed a high expression of BnMEB2 in mature (60-day-old leaves and could be obviously induced by exogenous iron stress in both roots and leaves. Over-expressed BnMEB2 in both Arabidopsis wild type and meb2 mutant seedlings resulted in greatly improved iron tolerability with no significant changes in the expression level of other vacuolar iron transporter genes. The mutant meb2 grew slowly and its root hair elongation was inhibited under high iron concentration condition while BnMEB2 over-expressed transgenic plants of the mutant restored the phenotypes with apparently higher iron storage in roots and dramatically increased iron content in the whole plant. Taken together, these results suggested that BnMEB2 was a VIT gene in rapeseed which was necessary for safe storage and vacuole detoxification function of excess iron to enhance the tolerance of iron toxicity. This research sheds light on a potentially new strategy for attenuating hazardous metal stress from environment and improving iron biofortification in Brassicaceae crops.

  12. Insights from the Fungus Fusarium oxysporum Point to High Affinity Glucose Transporters as Targets for Enhancing Ethanol Production from Lignocellulose

    Science.gov (United States)

    Ali, Shahin S.; Nugent, Brian; Mullins, Ewen; Doohan, Fiona M.

    2013-01-01

    Ethanol is the most-widely used biofuel in the world today. Lignocellulosic plant biomass derived from agricultural residue can be converted to ethanol via microbial bioprocessing. Fungi such as Fusarium oxysporum can simultaneously saccharify straw to sugars and ferment sugars to ethanol. But there are many bottlenecks that need to be overcome to increase the efficacy of microbial production of ethanol from straw, not least enhancement of the rate of fermentation of both hexose and pentose sugars. This research tested the hypothesis that the rate of sugar uptake by F. oxysporum would enhance the ethanol yields from lignocellulosic straw and that high affinity glucose transporters can enhance ethanol yields from this substrate. We characterized a novel hexose transporter (Hxt) from this fungus. The F. oxysporum Hxt represents a novel transporter with homology to yeast glucose signaling/transporter proteins Rgt2 and Snf3, but it lacks their C-terminal domain which is necessary for glucose signalling. Its expression level decreased with increasing glucose concentration in the medium and in a glucose uptake study the Km(glucose) was 0.9 mM, which indicated that the protein is a high affinity glucose transporter. Post-translational gene silencing or over expression of the Hxt in F. oxysporum directly affected the glucose and xylose transport capacity and ethanol yielded by F. oxysporum from straw, glucose and xylose. Thus we conclude that this Hxt has the capacity to transport both C5 and C6 sugars and to enhance ethanol yields from lignocellulosic material. This study has confirmed that high affinity glucose transporters are ideal candidates for improving ethanol yields from lignocellulose because their activity and level of expression is high in low glucose concentrations, which is very common during the process of consolidated processing. PMID:23382943

  13. Insights from the fungus Fusarium oxysporum point to high affinity glucose transporters as targets for enhancing ethanol production from lignocellulose.

    Directory of Open Access Journals (Sweden)

    Shahin S Ali

    Full Text Available Ethanol is the most-widely used biofuel in the world today. Lignocellulosic plant biomass derived from agricultural residue can be converted to ethanol via microbial bioprocessing. Fungi such as Fusarium oxysporum can simultaneously saccharify straw to sugars and ferment sugars to ethanol. But there are many bottlenecks that need to be overcome to increase the efficacy of microbial production of ethanol from straw, not least enhancement of the rate of fermentation of both hexose and pentose sugars. This research tested the hypothesis that the rate of sugar uptake by F. oxysporum would enhance the ethanol yields from lignocellulosic straw and that high affinity glucose transporters can enhance ethanol yields from this substrate. We characterized a novel hexose transporter (Hxt from this fungus. The F. oxysporum Hxt represents a novel transporter with homology to yeast glucose signaling/transporter proteins Rgt2 and Snf3, but it lacks their C-terminal domain which is necessary for glucose signalling. Its expression level decreased with increasing glucose concentration in the medium and in a glucose uptake study the Km((glucose was 0.9 mM, which indicated that the protein is a high affinity glucose transporter. Post-translational gene silencing or over expression of the Hxt in F. oxysporum directly affected the glucose and xylose transport capacity and ethanol yielded by F. oxysporum from straw, glucose and xylose. Thus we conclude that this Hxt has the capacity to transport both C5 and C6 sugars and to enhance ethanol yields from lignocellulosic material. This study has confirmed that high affinity glucose transporters are ideal candidates for improving ethanol yields from lignocellulose because their activity and level of expression is high in low glucose concentrations, which is very common during the process of consolidated processing.

  14. Investigation of transfection efficacy with transcatheter arterial transporting transferring to enhance p53 gene

    International Nuclear Information System (INIS)

    Lu Qin; Niu Huanzhang; Zhu Guangyu; An Yanli; Qiu Dinghong; Teng Gaojun

    2007-01-01

    Objective: To investigate the function of transferrin-DNA complex, transported by transferrin(Tf) and trans-arterial injection via interventional approach be the duel-target-orientated delivery and the transferring into malignant cells to get more effective therapy. Methods: p53-LipofectAMINE ligand with different concentrations of Tf (0, 10, 25, 50, 100 μg)transfected the 4 strains including LM6,Hep3B,YY and L02 in vitro to evaluate the gene transfection efficiency through western blot. Then, after setting up the VX2 hepatocarcinoma models, we delivered the Tf-p53-LipofectAMlNE complex into the hepatic arteries via interventional techniques to analyse the transfection efficiency in vivo. Results: Tf, within the range of l0 100 μg, could increase gene transfection efficiency mediated by liposome, and the efficiency increases with the raise of Tf concentration. Combination with interventional technique to inject Tf-DNA complex into tumor arteries, gene transfection efficiency was enhanced in rabbit models. Conclusion: Tf can enhance gene-liposome transfection efficiency, furthermore with combination of interventional catheter technique, there would be a potential duel-target-orientated gene therapy method. (authors)

  15. Overexpression of a bacterial mercury transporter MerT in Arabidopsis enhances mercury tolerance.

    Science.gov (United States)

    Xu, Sheng; Sun, Bin; Wang, Rong; He, Jia; Xia, Bing; Xue, Yong; Wang, Ren

    2017-08-19

    The phytoremediation by using of green plants in the removal of environmental pollutant is an environment friendly, green technology that is cost effective and energetically inexpensive. By using Agrobacterium-mediated gene transfer, we generated transgenic Arabidopsis plants ectopically expressing mercuric transport protein gene (merT) from Pseudomonas alcaligenes. Compared with wild-type (WT) plants, overexpressing PamerT in Arabidopsis enhanced the tolerance to HgCl 2 . Further results showed that the enhanced total activities or corresponding transcripts of antioxidant enzymes, including superoxide dismutase (SOD), catalase (CAT) and guaiacol peroxidase (POD) were observed in transgenic Arabidopsis under HgCl 2 stress. These results were confirmed by the alleviation of oxidative damage, as indicated by the decrease of thiobarbituric acid reactive substances (TBARS) contents and reactive oxygen species (ROS) accumulation. In addition, localization analysis of PaMerT in Arabidopsis protoplast showed that it is likely to be associated with vacuole. In all, PamerT increased mercury (Hg) tolerance in transgenic Arabidopsis, and decreased production of Hg-induced ROS, thereby protecting plants from oxidative damage. The present study has provided further evidence that bacterial MerT plays an important role in the plant tolerance to HgCl 2 and in reducing the production of ROS induced by HgCl 2 . Copyright © 2017 Elsevier Inc. All rights reserved.

  16. Impairment of GABA transporter GAT-1 terminates cortical recurrent network activity via enhanced phasic inhibition

    Directory of Open Access Journals (Sweden)

    Daniel Simon Razik

    2013-09-01

    Full Text Available In the central nervous system, GABA transporters (GATs very efficiently clear synaptically released GABA from the extracellular space, and thus exert a tight control on GABAergic inhibition. In neocortex, GABAergic inhibition is heavily recruited during recurrent phases of spontaneous action potential activity which alternate with neuronally quiet periods. Therefore, such activity should be quite sensitive to minute alterations of GAT function. Here, we explored the effects of a gradual impairment of GAT-1 and GAT-2/3 on spontaneous recurrent network activity – termed network bursts and silent periods – in organotypic slice cultures of rat neocortex. The GAT-1 specific antagonist NO-711 depressed activity already at nanomolar concentrations (IC50 for depression of spontaneous multiunit firing rate of 42 nM, reaching a level of 80% at 500-1000 nM. By contrast, the GAT-2/3 preferring antagonist SNAP-5114 had weaker and less consistent effects. Several lines of evidence pointed towards an enhancement of phasic GABAergic inhibition as the dominant activity-depressing mechanism: network bursts were drastically shortened, phasic GABAergic currents decayed slower, and neuronal excitability during ongoing activity was diminished. In silent periods, NO-711 had little effect on neuronal excitability or membrane resistance, quite in contrast to the effects of muscimol, a GABA mimetic which activates GABAA receptors tonically. Our results suggest that an enhancement of phasic GABAergic inhibition efficiently curtails cortical recurrent activity and may mediate antiepileptic effects of therapeutically relevant concentrations of GAT-1 antagonists.

  17. Investigation of transfection efficacy with transcatheter arterial transporting transferring to enhance p53 gene

    Energy Technology Data Exchange (ETDEWEB)

    Qin, Lu; Huanzhang, Niu; Guangyu, Zhu; Yanli, An; Dinghong, Qiu; Gaojun, Teng [Radiologic Department, Zhongda Hospital, Southeast Univ., Nanjing (China)

    2007-02-15

    Objective: To investigate the function of transferrin-DNA complex, transported by transferrin(Tf) and trans-arterial injection via interventional approach be the duel-target-orientated delivery and the transferring into malignant cells to get more effective therapy. Methods: p53-LipofectAMINE ligand with different concentrations of Tf (0, 10, 25, 50, 100 {mu}g)transfected the 4 strains including LM6,Hep3B,YY and L02 in vitro to evaluate the gene transfection efficiency through western blot. Then, after setting up the VX2 hepatocarcinoma models, we delivered the Tf-p53-LipofectAMlNE complex into the hepatic arteries via interventional techniques to analyse the transfection efficiency in vivo. Results: Tf, within the range of l0 100 {mu}g, could increase gene transfection efficiency mediated by liposome, and the efficiency increases with the raise of Tf concentration. Combination with interventional technique to inject Tf-DNA complex into tumor arteries, gene transfection efficiency was enhanced in rabbit models. Conclusion: Tf can enhance gene-liposome transfection efficiency, furthermore with combination of interventional catheter technique, there would be a potential duel-target-orientated gene therapy method. (authors)

  18. Enhancement of Bacterial Transport in Aerobic and Anaerobic Environments: Assessing the Effect of Metal Oxide Chemical Heterogeneities

    International Nuclear Information System (INIS)

    T.C. Onstott

    2005-01-01

    The goal of our research was to understand the fundamental processes that control microbial transport in physically and chemically heterogeneous aquifers and from this enhanced understanding determine the requirements for successful, field-scale delivery of microorganisms to metal contaminated subsurface sites. Our specific research goals were to determine; (1) the circumstances under which the preferential adsorption of bacteria to Fe, Mn, and Al oxyhydroxides influences field-scale bacterial transport, (2) the extent to which the adhesion properties of bacterial cells affect field-scale bacterial transport, (3) whether microbial Fe(III) reduction can enhance field-scale transport of Fe reducing bacteria (IRB) and other microorganisms and (4) the effect of field-scale physical and chemical heterogeneity on all three processes. Some of the spin-offs from this basic research that can improve biostimulation and bioaugmentation remediation efforts at contaminated DOE sites have included; (1) new bacterial tracking tools for viable bacteria; (2) an integrated protocol which combines subsurface characterization, laboratory-scale experimentation, and scale-up techniques to accurately predict field-scale bacterial transport; and (3) innovative and inexpensive field equipment and methods that can be employed to enhance Fe(III) reduction and microbial transport and to target microbial deposition under both aerobic and anaerobic conditions

  19. Intelligent transportation systems at international borders : a cross-cutting study : facilitating trade and enhancing transportation safety

    Science.gov (United States)

    2001-04-01

    The International Border Clearance (IBC) program was initiated under the provisions of the Intermodal Surface Transportation Efficiency Act (ISTEA) of 1991. The program was originally conceived as a means to test the feasibility of utilizing Intellig...

  20. Biogeochemical Processes Responsible for the Enhanced Transport of Plutonium Under transient Unsaturated Ground Water Conditions

    Energy Technology Data Exchange (ETDEWEB)

    Fred J. Molz, III

    2010-05-28

    To better understand longer-term vadose zone transport in southeastern soils, field lysimeter experiments were conducted at the Savannah River Site (SRS) near Aiken, SC, in the 1980s. Each of the three lysimeters analyzed herein contained a filter paper spiked with different Pu solutions, and they were left exposed to natural environmental conditions (including the growth of annual weed grasses) for 11 years. The resulting Pu activity measurements from each lysimeter core showed anomalous activity distributions below the source, with significant migration of Pu above the source. Such results are not explainable by adsorption phenomena alone. A transient variably saturated flow model with root water uptake was developed and coupled to a soil reactive transport model. Somewhat surprisingly, the fully transient analysis showed results nearly identical to those of a much simpler steady flow analysis performed previously. However, all phenomena studied were unable to produce the upward Pu transport observed in the data. This result suggests another transport mechanism such as Pu uptake by roots and upward transport due to transpiration. Thus, the variably saturated flow and reactive transport model was extended to include uptake and transport of Pu within the root xylem, along with computational methodology and results. In the extended model, flow velocity in the soil was driven by precipitation input along with transpiration and drainage. Water uptake by the roots determined the flow velocity in the root xylem, and this along with uptake of Pu in the transpiration stream drove advection and dispersion of the two Pu species in the xylem. During wet periods with high potential evapotranspiration, maximum flow velocities through the xylem would approached 600 cm/hr, orders of magnitude larger that flow velocities in the soil. Values for parameters and the correct conceptual viewpoint for Pu transport in plant xylem was uncertain. This motivated further experiments devoted

  1. Biogeochemical Processes Responsible for the Enhanced Transport of Plutonium Under transient Unsaturated Ground Water Conditions

    International Nuclear Information System (INIS)

    Molz, Fred J. III

    2010-01-01

    To better understand longer-term vadose zone transport in southeastern soils, field lysimeter experiments were conducted at the Savannah River Site (SRS) near Aiken, SC, in the 1980s. Each of the three lysimeters analyzed herein contained a filter paper spiked with different Pu solutions, and they were left exposed to natural environmental conditions (including the growth of annual weed grasses) for 11 years. The resulting Pu activity measurements from each lysimeter core showed anomalous activity distributions below the source, with significant migration of Pu above the source. Such results are not explainable by adsorption phenomena alone. A transient variably saturated flow model with root water uptake was developed and coupled to a soil reactive transport model. Somewhat surprisingly, the fully transient analysis showed results nearly identical to those of a much simpler steady flow analysis performed previously. However, all phenomena studied were unable to produce the upward Pu transport observed in the data. This result suggests another transport mechanism such as Pu uptake by roots and upward transport due to transpiration. Thus, the variably saturated flow and reactive transport model was extended to include uptake and transport of Pu within the root xylem, along with computational methodology and results. In the extended model, flow velocity in the soil was driven by precipitation input along with transpiration and drainage. Water uptake by the roots determined the flow velocity in the root xylem, and this along with uptake of Pu in the transpiration stream drove advection and dispersion of the two Pu species in the xylem. During wet periods with high potential evapotranspiration, maximum flow velocities through the xylem would approached 600 cm/hr, orders of magnitude larger that flow velocities in the soil. Values for parameters and the correct conceptual viewpoint for Pu transport in plant xylem was uncertain. This motivated further experiments devoted

  2. Transportation

    National Research Council Canada - National Science Library

    Adams, James; Carr, Ron; Chebl, Maroun; Coleman, Robert; Costantini, William; Cox, Robert; Dial, William; Jenkins, Robert; McGovern, James; Mueller, Peter

    2006-01-01

    ...., trains, ships, etc.) and maximizing intermodal efficiency. A healthy balance must be achieved between the flow of international commerce and security requirements regardless of transportation mode...

  3. Enhancement of transport of curcumin to brain in mice by poly(n-butylcyanoacrylate) nanoparticle

    Energy Technology Data Exchange (ETDEWEB)

    Sun Min; Gao Yan; Guo Chenyu; Cao Fengliang; Song Zhimei; Xi Yanwei; Yu Aihua; Li Aiguo; Zhai Guangxi, E-mail: professorzhai@yeah.ne [Shandong University, Department of Pharmaceutics, College of Pharmacy (China)

    2010-10-15

    Curcumin, a widely used coloring agent and spice in food, has a potential in blocking brain tumor formation and curing Alzheimer's disease. Due to the specific properties of blood-brain barrier (BBB), only traces of curcumin were transported across BBB. The aim of the present study was to design and characterize curcumin loaded polybutylcyanoacrylate nanoparticles (PBCN) coated with polysorbate 80, and to evaluate the effect of PBCN as a delivery system on carrying curcumin across BBB. Curcumin loaded nanoparticles were prepared by an anionic polymerization method, and they presented in a core-shell spherical shape under transmission electron microscopy, with an average diameter of 152.0 nm. The average drug loading was 21.1%. Physicochemical status of curcumin in the nanoparticles was confirmed with differential scanning colorimetry and Fourier transform infrared spectroscopy. The in vitro release behavior of drug from the nanoparticles was fitted to a double phase kinetics model. The studies of pharmacokinetic and bio-distribution to brain were conducted in mice after intravenous administration of the nanoparticle formulation at the dose of 5 mg/kg and curcumin solution at the dose of 10 mg/kg via the tail vein. The results showed that in plasma, the area under concentration-time curve (AUC{sub 0-{infinity}}) for curcumin loaded nanoparticles was greater than that for the control solution, moreover, the mean residence time of curcumin loaded nanoparticles was 14-fold that of the control solution. In brain, AUC{sub 0-{infinity}} for curcumin loaded nanoparticles was 2.53-fold that for the control solution. In conclusion, the present study demonstrated that PBCN could enhance the transport of curcumin to brain and have a potential as a delivery system to cross the BBB.

  4. Enhancement of transport of curcumin to brain in mice by poly( n-butylcyanoacrylate) nanoparticle

    Science.gov (United States)

    Sun, Min; Gao, Yan; Guo, Chenyu; Cao, Fengliang; Song, Zhimei; Xi, Yanwei; Yu, Aihua; Li, Aiguo; Zhai, Guangxi

    2010-10-01

    Curcumin, a widely used coloring agent and spice in food, has a potential in blocking brain tumor formation and curing Alzheimer's disease. Due to the specific properties of blood-brain barrier (BBB), only traces of curcumin were transported across BBB. The aim of the present study was to design and characterize curcumin loaded polybutylcyanoacrylate nanoparticles (PBCN) coated with polysorbate 80, and to evaluate the effect of PBCN as a delivery system on carrying curcumin across BBB. Curcumin loaded nanoparticles were prepared by an anionic polymerization method, and they presented in a core-shell spherical shape under transmission electron microscopy, with an average diameter of 152.0 nm. The average drug loading was 21.1%. Physicochemical status of curcumin in the nanoparticles was confirmed with differential scanning colorimetry and Fourier transform infrared spectroscopy. The in vitro release behavior of drug from the nanoparticles was fitted to a double phase kinetics model. The studies of pharmacokinetic and bio-distribution to brain were conducted in mice after intravenous administration of the nanoparticle formulation at the dose of 5 mg/kg and curcumin solution at the dose of 10 mg/kg via the tail vein. The results showed that in plasma, the area under concentration-time curve (AUC0-∞) for curcumin loaded nanoparticles was greater than that for the control solution, moreover, the mean residence time of curcumin loaded nanoparticles was 14-fold that of the control solution. In brain, AUC0-∞ for curcumin loaded nanoparticles was 2.53-fold that for the control solution. In conclusion, the present study demonstrated that PBCN could enhance the transport of curcumin to brain and have a potential as a delivery system to cross the BBB.

  5. Enhancement of transport of curcumin to brain in mice by poly(n-butylcyanoacrylate) nanoparticle

    International Nuclear Information System (INIS)

    Sun Min; Gao Yan; Guo Chenyu; Cao Fengliang; Song Zhimei; Xi Yanwei; Yu Aihua; Li Aiguo; Zhai Guangxi

    2010-01-01

    Curcumin, a widely used coloring agent and spice in food, has a potential in blocking brain tumor formation and curing Alzheimer's disease. Due to the specific properties of blood-brain barrier (BBB), only traces of curcumin were transported across BBB. The aim of the present study was to design and characterize curcumin loaded polybutylcyanoacrylate nanoparticles (PBCN) coated with polysorbate 80, and to evaluate the effect of PBCN as a delivery system on carrying curcumin across BBB. Curcumin loaded nanoparticles were prepared by an anionic polymerization method, and they presented in a core-shell spherical shape under transmission electron microscopy, with an average diameter of 152.0 nm. The average drug loading was 21.1%. Physicochemical status of curcumin in the nanoparticles was confirmed with differential scanning colorimetry and Fourier transform infrared spectroscopy. The in vitro release behavior of drug from the nanoparticles was fitted to a double phase kinetics model. The studies of pharmacokinetic and bio-distribution to brain were conducted in mice after intravenous administration of the nanoparticle formulation at the dose of 5 mg/kg and curcumin solution at the dose of 10 mg/kg via the tail vein. The results showed that in plasma, the area under concentration-time curve (AUC 0-∞ ) for curcumin loaded nanoparticles was greater than that for the control solution, moreover, the mean residence time of curcumin loaded nanoparticles was 14-fold that of the control solution. In brain, AUC 0-∞ for curcumin loaded nanoparticles was 2.53-fold that for the control solution. In conclusion, the present study demonstrated that PBCN could enhance the transport of curcumin to brain and have a potential as a delivery system to cross the BBB.

  6. Transport Pathways and Enhancement Mechanisms within Localized and Non-Localized Transport Regions in Skin Treated with Low-Frequency Sonophoresis and Sodium Lauryl Sulfate

    OpenAIRE

    Polat, Baris E.; Figueroa, Pedro L.; Blankschtein, Daniel; Langer, Robert

    2010-01-01

    Recent advances in transdermal drug delivery utilizing low-frequency sonophoresis (LFS) and sodium lauryl sulfate (SLS) have revealed that skin permeability enhancement is not homogenous across the skin surface. Instead, highly perturbed skin regions, known as localized transport regions (LTRs), exist. Despite these findings, little research has been conducted to identify intrinsic properties and formation mechanisms of LTRs and the surrounding less-perturbed non-LTRs. By independently analyz...

  7. Transportation

    International Nuclear Information System (INIS)

    Anon.

    1998-01-01

    Here is the decree of the thirtieth of July 1998 relative to road transportation, to trade and brokerage of wastes. It requires to firms which carry out a road transportation as well as to traders and to brokers of wastes to declare their operations to the prefect. The declaration has to be renewed every five years. (O.M.)

  8. Do buoyant plumes enhance cross-shelf transport in the Black Sea?

    Science.gov (United States)

    Sedakov, Roman; Zavialov, Peter; Izhitsky, Alexander

    2017-04-01

    either constant and different within each layer or a linear function of depth. In each case we obtain an analytical solution and derive a relation between seaward/shoreward transport and eddy viscosity. Both 2D and 3D models indicate that the stratified conditions damping vertical mixing lead to an increase of transport in the surface layer. This result corresponds well with the in situ observations, showing that buoyant plumes may indeed enhance advection of plume waters across shelf areas.

  9. Enhancing oxygen transport through Mixed-Ionic-and-Electronic-Conducting ceramic membranes

    Science.gov (United States)

    Yu, Anthony S.

    Ceramic membranes based on Mixed-Ionic-and-Electronic-Conducting (MIEC) oxides are capable of separating oxygen from air in the presence of an oxygen partial-pressure gradient. These MIEC membranes show great promise for oxygen consuming industrial processes, such as the production of syngas from steam reforming of natural gas (SRM), as well as for electricity generation in Solid Oxide Fuel Cells (SOFC). For both applications, the overall performance is dictated by the rate of oxygen transport across the membrane. Oxygen transport across MIEC membranes is composed of a bulk oxygen-ion diffusion process and surface processes, such as surface reactions and adsorption/desorption of gaseous reactants/products. The main goal of this thesis was to determine which process is rate-limiting in order to significantly enhance the overall rate of oxygen transport in MIEC membrane systems. The rate-limiting step was determined by evaluating the total resistance to oxygen transfer, Rtot. Rtot is the sum of a bulk diffusion resistance in the membrane itself, Rb, and interfacial loss components, Rs. Rb is a function of the membrane's ionic conductivity and thickness, while Rs arises primarily from slow surface-exchange kinetics that cause the P(O2) at the surfaces of the membrane to differ from the P(O 2) in the adjacent gas phases. Rtot can be calculated from the Nernst potential across the membrane and the measured oxygen flux. The rate-limiting process can be determined by evaluating the relative contributions of the various losses, Rs and Rb, to Rtot. Using this method, this thesis demonstrates that for most membrane systems, Rs is the dominating factor. In the development of membrane systems with high oxygen transport rates, thin membranes with high ionic conductivities are required to achieve fast bulk oxygen-ion diffusion. However, as membrane thickness is decreased, surface reaction kinetics become more important in determining the overall transport rate. The two

  10. Two gap superconductivity in Ba0.55K0.45Fe2As2 single crystals studied by the directional point-contact Andreev reflection spectroscopy

    International Nuclear Information System (INIS)

    Szabo, P.; Pribulova, Z.; Pristas, G.; Bud'ko, S.L.; Canfield, P.C.; Samuely, P.

    2009-01-01

    First directional point-contact Andreev reflection spectroscopy on the Ba 0.55 K 0.45 Fe 2 As 2 single crystals is presented. The spectra show significant differences when measured in the ab plane in comparison with those measured in the c direction. In the latter case no traces of superconducting energy gap could be found, just a reduced point-contact conductance persisting up to about 100 K and indicating reduced density of states. On the other hand within the ab plane two nodeless superconducting energy gaps Δ S ∼2-5 meV and Δ L ∼9-11 meV are detected.

  11. Development of Microorganisms with Improved Transport and Biosurfactant Activity for Enhanced Oil Recovery

    Energy Technology Data Exchange (ETDEWEB)

    M.J. McInerney; K.E. Duncan; N. Youssef; T. Fincher; S.K. Maudgalya; M.J. Folmsbee; R. Knapp; Randy R. Simpson; N.Ravi; D. Nagle

    2005-08-15

    growth at elevated salt concentrations to obtain candidates most suitable for microbial oil recovery. Seventy percent of the 205 strains tested, mostly strains of Bacillus mojavensis, Bacillus subtilis, Bacillus licheniformis, and Bacillus sonorensis, produced biosurfactants aerobically and 41% of the strains had biosurfactant activity greater than Bacillus mojavensis JF-2, the current candidate for oil recovery. Biosurfactant activity varied with the percentage of the 3-hydroxy-tetradecanoate isomers in the fatty acid portion of the biosurfactant. Changing the medium composition by incorporation of different precursors of 3-hydroxy tetradecanoate increased the activity of biosurfactant. The surface tension and critical micelle concentration of 15 different, biosurfactant-producing Bacillus strains was determined individually and in combination with other biosurfactants. Some biosurfactant mixtures were found to have synergistic effect on surface tension (e.g. surface tension was lowered from 41 to 31 mN/m in some cases) while others had a synergistic effect on CMD-1 values. We compared the transport abilities of spores from three Bacillus strains using a model porous system to study spore recovery and transport. Sand-packed columns were used to select for spores or cells with the best transport abilities through brine-saturated sand. Spores of Bacillus mojavensis strains JF-2 and ROB-2 and a natural recombinant, strain C-9, transported through sand at very high efficiencies. The earliest cells/spores that emerged from the column were regrown, allowed to sporulate, and applied to a second column. This procedure greatly enhanced the transport of strain C-9. Spores with enhanced transport abilities can be easily obtained and that the preparation of inocula for use in MEOR is feasible. We conducted a push-pull test to study in-situ biosurfactant production by exogenous biosurfactant producers to aid in oil recovery from depleted reservoirs. Five wells from the same

  12. Assembled microneedle arrays enhance the transport of compounds varying over a large range of molecular weight across human dermatomed skin

    NARCIS (Netherlands)

    Verbaan, F.J.; Bal, S.M.; van den Berg, D.J.; Groenink, W.H.H.; Verpoorten, H.; Lüttge, Regina; Bouwstra, J.A.

    2007-01-01

    In this study, we demonstrate the feasibility to use microneedle arrays manufactured from commercially available 30G hypodermal needles to enhance the transport of compounds up to a molecular weight of 72 kDa. Piercing of human dermatomed skin with microneedle arrays was studied by Trypan Blue

  13. Targeted PEG-based bioconjugates enhance the cellular uptake and transport of a HIV-1 TAT nonapeptide.

    Science.gov (United States)

    Ramanathan, S; Qiu, B; Pooyan, S; Zhang, G; Stein, S; Leibowitz, M J; Sinko, P J

    2001-12-13

    We previously described the enhanced cell uptake and transport of R.I-K(biotin)-Tat9, a large ( approximately 1500 Da) peptidic inhibitor of HIV-1 Tat protein, via SMVT, the intestinal biotin transporter. The aim of the present study was to investigate the feasibility of targeting biotinylated PEG-based conjugates to SMVT in order to enhance cell uptake and transport of Tat9. The 29 kDa peptide-loaded bioconjugate (PEG:(R.I-Cys-K(biotin)-Tat9)8) used in these studies contained eight copies of R.I-K(biotin)-Tat9 appended to PEG by means of a cysteine linkage. The absorptive transport of biotin-PEG-3400 (0.6-100 microM) and the bioconjugate (0.1-30 microM) was studied using Caco-2 cell monolayers. Inhibition of biotin-PEG-3400 by positive controls (biotin, biocytin, and desthiobiotin) was also determined. Uptake of these two compounds was also determined in CHO cells transfected with human SMVT (CHO/hSMVT) and control cells (CHO/pSPORT) over the concentration ranges of 0.05-12.5 microM and 0.003-30 microM, respectively. Nonbiotinylated forms of these two compounds, PEG-3350 and PEG:(R.I-Cys-K-Tat9)8, were used in the control studies. Biotin-PEG-3400 transport was found to be concentration-dependent and saturable in Caco-2 cells (K(m)=6.61 microM) and CHO/hSMVT cells (K(m)=1.26 microM). Transport/uptake was significantly inhibited by positive control substrates of SMVT. PEG:(R.I-Cys-K(biotin)Tat9)8 also showed saturable transport kinetics in Caco-2 cells (K(m)=6.13 microM) and CHO/hSMVT cells (K(m)=8.19 microM). Maximal uptake in molar equivalents of R.I-Cys-K(biotin)Tat9 was 5.7 times greater using the conjugate versus the biotinylated peptide alone. Transport of the nonbiotinylated forms was significantly lower (PPEG-3400 and PEG:(R.I-Cys-K(biotin)Tat9)8 interact with human SMVT to enhance the cellular uptake and transport of these larger molecules and that targeted bioconjugates may have potential for enhancing the cellular uptake and transport of small peptide

  14. Enhancing light absorption within the carrier transport length in quantum junction solar cells.

    Science.gov (United States)

    Fu, Yulan; Hara, Yukihiro; Miller, Christopher W; Lopez, Rene

    2015-09-10

    Colloidal quantum dot (CQD) solar cells have attracted tremendous attention because of their tunable absorption spectrum window and potentially low processing cost. Recently reported quantum junction solar cells represent a promising approach to building a rectifying photovoltaic device that employs CQD layers on each side of the p-n junction. However, the ultimate efficiency of CQD solar cells is still highly limited by their high trap state density in both p- and n-type CQDs. By modeling photonic structures to enhance the light absorption within the carrier transport length and by ensuring that the carrier generation and collection efficiencies were both augmented, our work shows that overall device current density could be improved. We utilized a two-dimensional numerical model to calculate the characteristics of patterned CQD solar cells based on a simple grating structure. Our calculation predicts a short circuit current density as high as 31  mA/cm2, a value nearly 1.5 times larger than that of the conventional flat design, showing the great potential value of patterned quantum junction solar cells.

  15. Giant larvaceans: biologically equivalent flapping flexible foils exhibit bending modes that enhance fluid transport

    Science.gov (United States)

    Katija, Kakani; Sherman, Alana; Robison, Bruce

    2016-11-01

    The midwater region of the ocean (below the euphotic zone and above the benthos) is one of the largest ecosystems on our planet, yet remains one of the least explored. Little-known marine organisms that inhabit midwater have developed life strategies that contribute to their evolutionary success, and may inspire engineering solutions for societally relevant challenges. A group of midwater organisms, known as giant larvaceans (genus Bathochordaeus), beat their tails to drive food and particle-laden water through complex, mucus filtering structures to feed. Giant larvaceans, whose motion and kinematics resemble flapping flexible foils, range in size from 1 to 10 cm in length, and can be found between the surface and 400 m. Using remotely-operated vehicles and DeepPIV, an instrument that enables in situ particle image velocimetry (PIV) measurements, the filtration rates and kinematics of giant larvaceans were investigated. These measurements yielded filtration rates for giant larvaceans as high as 80 L/hr, which exceeds expected filtration rates by a factor of 2 when compared with other larvacean groups. Comparing tail kinematics between Bathochordeaus and smaller larvaceans reveals differences in tail bending modes, where a hinge is present throughout the tail beat in giant larvaceans. Using laboratory PIV measurements with swimming animals and soft-bodied mechanical mimics, we reveal how these differences in tail kinematics can lead to enhanced fluid transport. This work has been supported by the Packard Foundation.

  16. Photoconductivity enhancement and charge transport properties in ruthenium-containing block copolymer/carbon nanotube hybrids.

    Science.gov (United States)

    Lo, Kin Cheung; Hau, King In; Chan, Wai Kin

    2018-04-05

    Functional polymer/carbon nanotube (CNT) hybrid materials can serve as a good model for light harvesting systems based on CNTs. This paper presents the synthesis of block copolymer/CNT hybrids and the characterization of their photocurrent responses by both experimental and computational approaches. A series of functional diblock copolymers was synthesized by reversible addition-fragmentation chain transfer polymerizations for the dispersion and functionalization of CNTs. The block copolymers contain photosensitizing ruthenium complexes and modified pyrene-based anchoring units. The photocurrent responses of the polymer/CNT hybrids were measured by photoconductive atomic force microscopy (PCAFM), from which the experimental data were analyzed by vigorous statistical models. The difference in photocurrent response among different hybrids was correlated to the conformations of the hybrids, which were elucidated by molecular dynamics simulations, and the electronic properties of polymers. The photoresponse of the block copolymer/CNT hybrids can be enhanced by introducing an electron-accepting block between the photosensitizing block and the CNT. We have demonstrated that the application of a rigorous statistical methodology can unravel the charge transport properties of these hybrid materials and provide general guidelines for the design of molecular light harvesting systems.

  17. Microfluidic Transduction Harnesses Mass Transport Principles to Enhance Gene Transfer Efficiency.

    Science.gov (United States)

    Tran, Reginald; Myers, David R; Denning, Gabriela; Shields, Jordan E; Lytle, Allison M; Alrowais, Hommood; Qiu, Yongzhi; Sakurai, Yumiko; Li, William C; Brand, Oliver; Le Doux, Joseph M; Spencer, H Trent; Doering, Christopher B; Lam, Wilbur A

    2017-10-04

    Ex vivo gene therapy using lentiviral vectors (LVs) is a proven approach to treat and potentially cure many hematologic disorders and malignancies but remains stymied by cumbersome, cost-prohibitive, and scale-limited production processes that cannot meet the demands of current clinical protocols for widespread clinical utilization. However, limitations in LV manufacture coupled with inefficient transduction protocols requiring significant excess amounts of vector currently limit widespread implementation. Herein, we describe a microfluidic, mass transport-based approach that overcomes the diffusion limitations of current transduction platforms to enhance LV gene transfer kinetics and efficiency. This novel ex vivo LV transduction platform is flexible in design, easy to use, scalable, and compatible with standard cell transduction reagents and LV preparations. Using hematopoietic cell lines, primary human T cells, primary hematopoietic stem and progenitor cells (HSPCs) of both murine (Sca-1 + ) and human (CD34 + ) origin, microfluidic transduction using clinically processed LVs occurs up to 5-fold faster and requires as little as one-twentieth of LV. As an in vivo validation of the microfluidic-based transduction technology, HSPC gene therapy was performed in hemophilia A mice using limiting amounts of LV. Compared to the standard static well-based transduction protocols, only animals transplanted with microfluidic-transduced cells displayed clotting levels restored to normal. Copyright © 2017 The Author(s). Published by Elsevier Inc. All rights reserved.

  18. 3-bromopyruvate enhanced daunorubicin-induced cytotoxicity involved in monocarboxylate transporter 1 in breast cancer cells.

    Science.gov (United States)

    Liu, Zhe; Sun, Yiming; Hong, Haiyu; Zhao, Surong; Zou, Xue; Ma, Renqiang; Jiang, Chenchen; Wang, Zhiwei; Li, Huabin; Liu, Hao

    2015-01-01

    Increasing evidence demonstrates that the hexokinase inhibitor 3-bromopyruvate (3-BrPA) induces the cell apoptotic death by inhibiting ATP generation in human cancer cells. Interestingly, some tumor cell lines are less sensitive to 3-BrPA-induced apoptosis than others. Moreover, the molecular mechanism of 3-BrPA-trigged apoptosis is unclear. In the present study, we examined the effects of 3-BrPA on the viability of the breast cancer cell lines MDA-MB-231 and MCF-7. We further investigated the potential roles of monocarboxylate transporter 1 (MCT1) in drug accumulation and efflux of breast cancer cells. Finally, we explored whether 3-BrPA enhanced daunorubicin (DNR)-induced cytotoxicity through regulation of MCT1 in breast cancer cells. MTT and colony formation assays were used to measure cell viability. Western blot analysis, flow cytometric analysis and fluorescent microscopy were used to determine the molecular mechanism of actions of MCT1 in different breast cancer cell lines. Whole-body bioluminescence imaging was used to investigate the effect of 3-BrPA in vivo. We found that 3-BrPA significantly inhibited cell growth and induced apoptosis in MCF-7 cell line, but not in MDA-MB-231 cells. Moreover, we observed that 3-BrPA efficiently enhanced DNR-induced cytotoxicity in MCF-7 cells by inhibiting the activity of ATP-dependent efflux pumps. We also found that MCT1 overexpression increased the efficacy of 3-BrPA in MDA-MB-231 cells. 3-BrPA markedly suppressed subcutaneous tumor growth in combination with DNR in nude mice implanted with MCF-7 cells. Lastly, our whole-body bioluminescence imaging data indicated that 3-BrPA promoted DNR accumulation in tumors. These findings collectively suggest that 3-BrPA enhanced DNR antitumor activity in breast cancer cells involved MCT-1, suggesting that inhibition of glycolysis could be an effective therapeutic approach for breast cancer treatment.

  19. Understanding and removing surface states limiting charge transport in TiO2 nanowire arrays for enhanced optoelectronic device performance.

    Science.gov (United States)

    Sheng, Xia; Chen, Liping; Xu, Tao; Zhu, Kai; Feng, Xinjian

    2016-03-01

    Charge transport within electrode materials plays a key role in determining the optoelectronic device performance. Aligned single-crystal TiO 2 nanowire arrays offer an ideal electron transport path and are expected to have higher electron mobility. Unfortunately, their transport is found not to be superior to that in nanoparticle films. Here we show that the low electron transport in rutile TiO 2 nanowires is mainly caused by surface traps in relatively deep energy levels, which cannot be removed by conventional approaches, such as oxygen annealing treatment. Moreover, we demonstrate an effective wet-chemistry approach to minimize these trap states, leading to over 20-fold enhancement in electron diffusion coefficient and 62% improvement in solar cell performance. On the basis of our results, the potential of TiO 2 NWs can be developed and well-utilized, which is significantly important for their practical applications.

  20. Transportation

    National Research Council Canada - National Science Library

    Allshouse, Michael; Armstrong, Frederick Henry; Burns, Stephen; Courts, Michael; Denn, Douglas; Fortunato, Paul; Gettings, Daniel; Hansen, David; Hoffman, D. W; Jones, Robert

    2007-01-01

    .... The ability of the global transportation industry to rapidly move passengers and products from one corner of the globe to another continues to amaze even those wise to the dynamics of such operations...

  1. 78 FR 60755 - Hazardous Materials: Enhanced Enforcement Procedures-Resumption of Transportation

    Science.gov (United States)

    2013-10-02

    ... material,'' we envisioned etiological agents, such as biological products, infectious substances, medical... accidents or incidents involving the transportation of hazardous material. In order to achieve a uniform... DEPARTMENT OF TRANSPORTATION Pipeline and Hazardous Materials Safety Administration 49 CFR Part...

  2. Electron and Cooper-pair transport across a single magnetic molecule explored with a scanning tunneling microscope

    Science.gov (United States)

    Brand, J.; Gozdzik, S.; Néel, N.; Lado, J. L.; Fernández-Rossier, J.; Kröger, J.

    2018-05-01

    A scanning tunneling microscope is used to explore the evolution of electron and Cooper-pair transport across single Mn-phthalocyanine molecules adsorbed on Pb(111) from tunneling to contact ranges. Normal-metal as well as superconducting tips give rise to a gradual transition of the Bardeen-Cooper-Schrieffer energy gap in the tunneling range into a zero-energy resonance close to and at contact. Supporting transport calculations show that in the normal-metal-superconductor junctions this resonance reflects the merging of in-gap Yu-Shiba-Rusinov states as well as the onset of Andreev reflection. For the superconductor-superconductor contacts, the zero-energy resonance is rationalized in terms of a finite Josephson current that is carried by phase-dependent Andreev and Yu-Shiba-Rusinov levels.

  3. Gadoxetate-enhanced MR imaging and compartmental modelling to assess hepatocyte bidirectional transport function in rats with advanced liver fibrosis

    Energy Technology Data Exchange (ETDEWEB)

    Giraudeau, Celine; Leporq, Benjamin; Doblas, Sabrina [University Paris Diderot, Sorbonne Paris Cite, Hopital Beaujon, Laboratory of Imaging Biomarkers, UMR1149 Inserm, Clichy (France); Lagadec, Matthieu; Daire, Jean-Luc; Van Beers, Bernard E. [University Paris Diderot, Sorbonne Paris Cite, Hopital Beaujon, Laboratory of Imaging Biomarkers, UMR1149 Inserm, Clichy (France); Beaujon University Hospital Paris Nord, Department of Radiology, Clichy (France); Pastor, Catherine M. [University Paris Diderot, Sorbonne Paris Cite, Hopital Beaujon, Laboratory of Imaging Biomarkers, UMR1149 Inserm, Clichy (France); Hopitaux Universitaires de Geneve, Departement d' Imagerie et des Sciences de l' Information Medicale, Geneva (Switzerland)

    2017-05-15

    Changes in the expression of hepatocyte membrane transporters in advanced fibrosis decrease the hepatic transport function of organic anions. The aim of our study was to assess if these changes can be evaluated with pharmacokinetic analysis of the hepatobiliary transport of the MR contrast agent gadoxetate. Dynamic gadoxetate-enhanced MRI was performed in 17 rats with advanced fibrosis and 8 normal rats. After deconvolution, hepatocyte three-compartmental analysis was performed to calculate the hepatocyte influx, biliary efflux and sinusoidal backflux rates. The expression of Oatp1a1, Mrp2 and Mrp3 organic anion membrane transporters was assessed with reverse transcription polymerase chain reaction. In the rats with advanced fibrosis, the influx and efflux rates of gadoxetate decreased and the backflux rate increased significantly (p = 0.003, 0.041 and 0.010, respectively). Significant correlations were found between influx and Oatp1a1 expression (r = 0.78, p < 0.001), biliary efflux and Mrp2 (r = 0.50, p = 0.016) and sinusoidal backflux and Mrp3 (r = 0.61, p = 0.002). These results show that changes in the bidirectional organic anion hepatocyte transport function in rats with advanced liver fibrosis can be assessed with compartmental analysis of gadoxetate-enhanced MRI. (orig.)

  4. Gadoxetate-enhanced MR imaging and compartmental modelling to assess hepatocyte bidirectional transport function in rats with advanced liver fibrosis

    International Nuclear Information System (INIS)

    Giraudeau, Celine; Leporq, Benjamin; Doblas, Sabrina; Lagadec, Matthieu; Daire, Jean-Luc; Van Beers, Bernard E.; Pastor, Catherine M.

    2017-01-01

    Changes in the expression of hepatocyte membrane transporters in advanced fibrosis decrease the hepatic transport function of organic anions. The aim of our study was to assess if these changes can be evaluated with pharmacokinetic analysis of the hepatobiliary transport of the MR contrast agent gadoxetate. Dynamic gadoxetate-enhanced MRI was performed in 17 rats with advanced fibrosis and 8 normal rats. After deconvolution, hepatocyte three-compartmental analysis was performed to calculate the hepatocyte influx, biliary efflux and sinusoidal backflux rates. The expression of Oatp1a1, Mrp2 and Mrp3 organic anion membrane transporters was assessed with reverse transcription polymerase chain reaction. In the rats with advanced fibrosis, the influx and efflux rates of gadoxetate decreased and the backflux rate increased significantly (p = 0.003, 0.041 and 0.010, respectively). Significant correlations were found between influx and Oatp1a1 expression (r = 0.78, p < 0.001), biliary efflux and Mrp2 (r = 0.50, p = 0.016) and sinusoidal backflux and Mrp3 (r = 0.61, p = 0.002). These results show that changes in the bidirectional organic anion hepatocyte transport function in rats with advanced liver fibrosis can be assessed with compartmental analysis of gadoxetate-enhanced MRI. (orig.)

  5. Evidence for Crossed Andreev Reflections in (100)YBa2Cu3O7+δ-SrRuO3 superconductor-ferromagnet bilayers

    International Nuclear Information System (INIS)

    Asulin, I.; Yuli, O.; Millo, O.; Koren, G.

    2005-01-01

    Full Text:Since the ferromagnetic side of a superconductor-ferromagnet junction is spin polarized, Andreev reflections are suppressed. Consequently, the proximity induced superconductor order parameter in the ferromagnet is expected to decay rapidly, on the order of a nm, the typical coherence length in a ferromagnet. Our scanning tunneling spectroscopy measurements on thin epitaxial (100)YBa 2 Cu 3 O 7+ δ-SrRuO 3 (YBaCuO-SrO) bilayers, where SrO is a ferromagnet, indeed show that on most of the junction area the superconductor order parameter vanishes in the SrO layers thicker than 8 nm. However, we find localized regions, arranged along narrow (< 10 nm) stripes, where the order parameter (superconductor-like gap structure) penetrates the ferromagnet over more than 20 nm. This is attributed to 'Crossed Andreev Reflections,' taking place at domain boundaries, where an electron from one magnetic domain is retro reflected as a hole with opposite spin in an adjacent domain. Our observation may account for the (not abundant) cases where a long-range proximity effect was found in superconductor-ferromagnet proximity systems

  6. Inhibition of serotonin transporters disrupts the enhancement of fear memory extinction by 3,4-methylenedioxymethamphetamine (MDMA).

    Science.gov (United States)

    Young, Matthew B; Norrholm, Seth D; Khoury, Lara M; Jovanovic, Tanja; Rauch, Sheila A M; Reiff, Collin M; Dunlop, Boadie W; Rothbaum, Barbara O; Howell, Leonard L

    2017-10-01

    3,4-Methylenedioxymethamphetamine (MDMA) persistently improves symptoms of post-traumatic stress disorder (PTSD) when combined with psychotherapy. Studies in rodents suggest that these effects can be attributed to enhancement of fear memory extinction. Therefore, MDMA may improve the effects of exposure-based therapy for PTSD, particularly in treatment-resistant patients. However, given MDMA's broad pharmacological profile, further investigation is warranted before moving to a complex clinical population. We aimed to inform clinical research by providing a translational model of MDMA's effect, and elucidating monoaminergic mechanisms through which MDMA enhances fear extinction. We explored the importance of monoamine transporters targeted by MDMA to fear memory extinction, as measured by reductions in conditioned freezing and fear-potentiated startle (FPS) in mice. Mice were treated with selective inhibitors of individual monoamine transporters prior to combined MDMA treatment and fear extinction training. MDMA enhanced the lasting extinction of FPS. Acute and chronic treatment with a 5-HT transporter (5-HTT) inhibitor blocked MDMA's effect on fear memory extinction. Acute inhibition of dopamine (DA) and norepinephrine (NE) transporters had no effect. 5-HT release alone did not enhance extinction. Blockade of MDMA's effect by 5-HTT inhibition also downregulated 5-HT 2A -mediated behavior, and 5-HT 2A antagonism disrupted MDMA's effect on extinction. We validate enhancement of fear memory extinction by MDMA in a translational behavioral model, and reveal the importance of 5-HTT and 5-HT 2A receptors to this effect. These observations support future clinical research of MDMA as an adjunct to exposure therapy, and provide important pharmacological considerations for clinical use in a population frequently treated with 5-HTT inhibitors.

  7. Modeling multi-component transport and enhanced anaerobic dechlorination processes in a single fracture-clay matrix system

    DEFF Research Database (Denmark)

    Chambon, Julie Claire Claudia; Broholm, Mette Martina; Binning, Philip John

    2010-01-01

    Clayey tills contaminated with chlorinated solvents are a threat to groundwater and are difficult to remediate. A numerical model is developed for assessing leaching processes and for simulating the remediation via enhanced anaerobic dechlorination. The model simulates the transport...... to the physical processes, mainly diffusion in the matrix, than to the biogeochemical processes, when dechlorination is assumed to take place in a limited reaction zone only. The inclusion of sequential dechlorination in clay fracture transport models is crucial, as the contaminant flux to the aquifer...

  8. International cooperation for the development of consistent and stable transportation regulations to promote and enhance safety and security

    International Nuclear Information System (INIS)

    Strosnider, J.

    2004-01-01

    International commerce of radioactive materials crosses national boundaries, linking separate regulatory institutions with a common purpose and making it necessary for these institutions to work together in order to achieve common safety goals in a manner that does not place an undue burden on industry and commerce. Widespread and increasing use of radioactive materials across the world has led to increases in the transport of radioactive materials. The demand for consistency in the oversight of international transport has also increased to prevent unnecessary delays and costs associated with incongruent or redundant regulatory requirements by the various countries through which radioactive material is transported. The International Atomic Energy Agency (IAEA) is the authority for international regulation of transportation of radioactive materials responsible for promulgation of regulations and guidance for the establishment of acceptable methods of transportation for the international community. As such, the IAEA is seen as the focal point for consensus building between its Member States to develop consistency in transportation regulations and reviews and to ensure the safe and secure transport of radioactive material. International cooperation is also needed to ensure stability in our regulatory processes. Changes to transportation regulations should be based on an anticipated safety benefit supported by risk information and insights gained from continuing experience, evaluation, and research studies. If we keep safety as the principle basis for regulatory changes, regulatory stability will be enhanced. Finally, as we endeavour to maintain consistency and stability in our international regulations, we must be mindful of the new security challenges that lay before the international community as a result of a changing terrorist environment. Terrorism is a problem of global concern that also requires international cooperation and support, as we look for ways to

  9. Optical imaging of the transport properties of S-Sm-S junctions

    International Nuclear Information System (INIS)

    Tsumura, K; Nomura, S; Akazaki, T; Takayanagi, H

    2009-01-01

    We study the optical effects on superconductor-normal metal superconductor (S-Sm-S) junctions composed of two-dimensional electron gas (2DEG) in a GaAs/AlGaAs heterostructure and NbN superconducting electrodes. When the whole junction area was illuminated at λ = 800 nm, we observe a reduction in the normal resistance due to an increase in the sheet carrier density of the 2DEG, and the enhancement of the Andreev reflection probability. To reveal its origin, we performed scanning photo-voltage measurement by employing an optical microscope. The obtained image plots show maxima and minima of the photo-voltage change along the S-Sm interfaces. Those structures are considered to reflect the modulation of the barrier height at S-Sm interface and the increase in the scattering by photo-generated carriers. It is demonstrated that the scanning photo-voltage measurement is one of the most powerful tools as a local probe of the transport properties of S-Sm-S junctions.

  10. Two-terminal charge tunneling: Disentangling Majorana zero modes from partially separated Andreev bound states in semiconductor-superconductor heterostructures

    Science.gov (United States)

    Moore, Christopher; Stanescu, Tudor D.; Tewari, Sumanta

    2018-04-01

    We show that a pair of overlapping Majorana bound states (MBSs) forming a partially separated Andreev bound state (ps-ABS) represents a generic low-energy feature in spin-orbit-coupled semiconductor-superconductor (SM-SC) hybrid nanowire in the presence of a Zeeman field. The ps-ABS interpolates continuously between the "garden variety" ABS, which consists of two MBSs sitting on top of each other, and the topologically protected Majorana zero modes (MZMs), which are separated by a distance given by the length of the wire. The really problematic ps-ABSs consist of component MBSs separated by a distance of the order of the characteristic Majorana decay length ξ , and have nearly zero energy in a significant range of control parameters, such as the Zeeman field and chemical potential, within the topologically trivial phase. Despite being topologically trivial, such ps-ABSs can generate signatures identical to MZMs in local charge tunneling experiments. In particular, the height of the zero-bias conductance peak (ZBCP) generated by ps-ABSs has the quantized value 2 e2/h , and it can remain unchanged in an extended range of experimental parameters, such as Zeeman field and the tunnel barrier height. We illustrate the formation of such low-energy robust ps-ABSs in two experimentally relevant situations: a hybrid SM-SC system consisting of a proximitized nanowire coupled to a quantum dot and the SM-SC system in the presence of a spatially varying inhomogeneous potential. We then show that, unlike local measurements, a two-terminal experiment involving charge tunneling at both ends of the wire is capable of distinguishing between the generic ps-ABSs and the non-Abelian MZMs. While the MZMs localized at the opposite ends of the wire generate correlated differential conduction spectra, including correlations in energy splittings and critical Zeeman fields associated with the emergence of the ZBCPs, such correlations are absent if the ZBCPs are due to ps-ABSs emerging in the

  11. Enhanced discreteness, renormalization, and anomalous transport in turbulent plasma. Final technical report, 15 September 1991--14 September 1992

    International Nuclear Information System (INIS)

    Johnston, S.

    1997-01-01

    The Principal Investigator, Professor Shayne Johnston, devoted 25% of his time during the academic year 1991--92 to this grant. The central idea underlying this project was a renormalized vision of a turbulent plasma in which electrons become microclumps, discreteness is thereby enhanced,and transport processes, still essentially classical, become anomalous. After two years of continued investigation, the PI believes strongly that this vision remains viable and compelling as an approach to electron heat conduction in the tokamak core. The simple analysis presented below shows that electrostatic waves can indeed correlate resonant repelling particles on length scales much shorter than a wavelength, thus causing enhanced discreteness within Debye clouds

  12. Enhancing Transportation Education through On-line Simulation using an Agent-Based Demand and Assignment Model

    OpenAIRE

    Shanjiang Zhu; Feng Xie; David Levinson

    2005-01-01

    This research explores the effectiveness of using simulation as a tool for enhancing classroom learning in the Civil Engineering Department of the University of Minnesota at Twin Cities. The authors developed a modern transportation planning software package, Agent-based Demand and Assignment Model (ADAM), that is consistent with our present understanding of travel behavior, that is platform independent, and that is easy to learn and is thus usable by students. An in-class project incorporate...

  13. En Route Care in Confined Spaces: Impact of Transport, Immobilization Practices, Space Constraints, and Medical Awareness Enhancements

    Science.gov (United States)

    2017-10-01

    physical space , ergonomics , and enhancement of medical awareness. Outcomes of the project will provide significant information and tools that can be...This group of research projects was designed to look at various aspects of transport, immobilization, optimal physical space , ergonomics , and...Devereux, J. 2002. The nature of work -related neck and upper limb musculoskeletal disorders. Applied Ergonomics . 33(3): 207-17. Chaffin, D.B

  14. Real-Time Transportation Mode Identification Using Artificial Neural Networks Enhanced with Mode Availability Layers: A Case Study in Dubai

    Directory of Open Access Journals (Sweden)

    Young-Ji Byon

    2017-09-01

    Full Text Available Traditionally, departments of transportation (DOTs have dispatched probe vehicles with dedicated vehicles and drivers for monitoring traffic conditions. Emerging assisted GPS (AGPS and accelerometer-equipped smartphones offer new sources of raw data that arise from voluntarily-traveling smartphone users provided that their modes of transportation can correctly be identified. By introducing additional raster map layers that indicate the availability of each mode, it is possible to enhance the accuracy of mode detection results. Even in its simplest form, an artificial neural network (ANN excels at pattern recognition with a relatively short processing timeframe once it is properly trained, which is suitable for real-time mode identification purposes. Dubai is one of the major cities in the Middle East and offers unique environments, such as a high density of extremely high-rise buildings that may introduce multi-path errors with GPS signals. This paper develops real-time mode identification ANNs enhanced with proposed mode availability geographic information system (GIS layers, firstly for a universal mode detection and, secondly for an auto mode detection for the particular intelligent transportation system (ITS application of traffic monitoring, and compares the results with existing approaches. It is found that ANN-based real-time mode identification, enhanced by mode availability GIS layers, significantly outperforms the existing methods.

  15. Transportation

    Science.gov (United States)

    2007-01-01

    Faculty ii INDUSTRY TRAVEL Domestic Assistant Deputy Under Secretary of Defense (Transportation Policy), Washington, DC Department of...developed between the railroad and trucking industries. Railroads: Today’s seven Class I freight railroad systems move 42% of the nation’s intercity ...has been successfully employed in London to reduce congestion and observed by this industry study during its travels . It is currently being

  16. Transport pathways and enhancement mechanisms within localized and non-localized transport regions in skin treated with low-frequency sonophoresis and sodium lauryl sulfate.

    Science.gov (United States)

    Polat, Baris E; Figueroa, Pedro L; Blankschtein, Daniel; Langer, Robert

    2011-02-01

    Recent advances in transdermal drug delivery utilizing low-frequency sonophoresis (LFS) and sodium lauryl sulfate (SLS) have revealed that skin permeability enhancement is not homogenous across the skin surface. Instead, highly perturbed skin regions, known as localized transport regions (LTRs), exist. Despite these findings, little research has been conducted to identify intrinsic properties and formation mechanisms of LTRs and the surrounding less-perturbed non-LTRs. By independently analyzing LTR, non-LTR, and total skin samples treated at multiple LFS frequencies, we found that the pore radii (r(pore)) within non-LTRs are frequency-independent, ranging from 18.2 to 18.5 Å, but significantly larger than r(pore) of native skin samples (13.6 Å). Conversely, r(pore) within LTRs increase significantly with decreasing frequency from 161 to 276 Å and to ∞ (>300 Å) for LFS/SLS-treated skin at 60, 40, and 20 kHz, respectively. Our findings suggest that different mechanisms contribute to skin permeability enhancement within each skin region. We propose that the enhancement mechanism within LTRs is the frequency-dependent process of cavitation-induced microjet collapse at the skin surface, whereas the increased r(pore) values in non-LTRs are likely due to SLS perturbation, with enhanced penetration of SLS into the skin resulting from the frequency-independent process of microstreaming. Copyright © 2010 Wiley-Liss, Inc.

  17. Transport Pathways and Enhancement Mechanisms within Localized and Non-Localized Transport Regions in Skin Treated with Low-Frequency Sonophoresis and Sodium Lauryl Sulfate

    Science.gov (United States)

    Polat, Baris E.; Figueroa, Pedro L.; Blankschtein, Daniel; Langer, Robert

    2011-01-01

    Recent advances in transdermal drug delivery utilizing low-frequency sonophoresis (LFS) and sodium lauryl sulfate (SLS) have revealed that skin permeability enhancement is not homogenous across the skin surface. Instead, highly perturbed skin regions, known as localized transport regions (LTRs), exist. Despite these findings, little research has been conducted to identify intrinsic properties and formation mechanisms of LTRs and the surrounding less-perturbed non-LTRs. By independently analyzing LTR, non-LTR, and total skin samples treated at multiple LFS frequencies, we found that the pore radii (rpore) within non-LTRs are frequency-independent, ranging from 18.2 – 18.5 Å, but significantly larger than rpore of native skin samples (13.6 Å). Conversely, rpore within LTRs increases significantly with decreasing frequency from 161 Å, to 276 Å, and to ∞ (>300Å) for LFS/SLS-treated skin at 60 kHz, 40 kHz, and 20 kHz, respectively. Our findings suggest that different mechanisms contribute to skin permeability enhancement within each skin region. We propose that the enhancement mechanism within LTRs is the frequency-dependent process of cavitation-induced microjet collapse at the skin surface, while the increased rpore values in non-LTRs are likely due to SLS perturbation, with enhanced penetration of SLS into the skin resulting from the frequency-independent process of microstreaming. PMID:20740667

  18. Thermal transport across solid-solid interfaces enhanced by pre-interface isotope-phonon scattering

    Science.gov (United States)

    Lee, Eungkyu; Luo, Tengfei

    2018-01-01

    Thermal transport across solid interfaces can play critical roles in the thermal management of electronics. In this letter, we use non-equilibrium molecular dynamics simulations to investigate the isotope effect on the thermal transport across SiC/GaN interfaces. It is found that engineered isotopes (e.g., 10% 15N or 71Ga) in the GaN layer can increase the interfacial thermal conductance compared to the isotopically pure case by as much as 23%. Different isotope doping features, such as the isotope concentration, skin depth of the isotope region, and its distance from the interface, are investigated, and all of them lead to increases in thermal conductance. Studies of spectral temperatures of phonon modes indicate that interfacial thermal transport due to low-frequency phonons (transport. This work may provide insights into interfacial thermal transport and useful guidance to practical material design.

  19. Enhancements to the Combinatorial Geometry Particle Tracker in the Mercury Monte Carlo Transport Code: Embedded Meshes and Domain Decomposition

    International Nuclear Information System (INIS)

    Greenman, G.M.; O'Brien, M.J.; Procassini, R.J.; Joy, K.I.

    2009-01-01

    Two enhancements to the combinatorial geometry (CG) particle tracker in the Mercury Monte Carlo transport code are presented. The first enhancement is a hybrid particle tracker wherein a mesh region is embedded within a CG region. This method permits efficient calculations of problems with contain both large-scale heterogeneous and homogeneous regions. The second enhancement relates to the addition of parallelism within the CG tracker via spatial domain decomposition. This permits calculations of problems with a large degree of geometric complexity, which are not possible through particle parallelism alone. In this method, the cells are decomposed across processors and a particles is communicated to an adjacent processor when it tracks to an interprocessor boundary. Applications that demonstrate the efficacy of these new methods are presented

  20. Silicon-enhanced resistance to cadmium toxicity in Brassica chinensis L. is attributed to Si-suppressed cadmium uptake and transport and Si-enhanced antioxidant defense capacity

    Energy Technology Data Exchange (ETDEWEB)

    Song Alin [College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095 (China); Li Zhaojun [Ministry of Agriculture Key Laboratory of Crop Nutrition and Fertilization, Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing 100081 (China); Zhang Jie [College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095 (China); Xue Gaofeng; Fan Fenliang [Ministry of Agriculture Key Laboratory of Crop Nutrition and Fertilization, Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing 100081 (China); Liang Yongchao, E-mail: ycliang@caas.ac.cn [College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095 (China); Ministry of Agriculture Key Laboratory of Crop Nutrition and Fertilization, Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing 100081 (China); Key Laboratory of Oasis Eco-Agriculture, College of Agriculture, Shihezi University, Shihezi 832003 (China)

    2009-12-15

    A series of hydroponics experiments were performed to investigate roles of silicon (Si) in enhancing cadmium (Cd) tolerance in two pakchoi (Brassica chinensis L.) cultivars: i.e. cv. Shanghaiqing, a Cd-sensitive cultivar, and cv. Hangyoudong, a Cd-tolerant cultivar. Plants were grown under 0.5 and 5 mg Cd L{sup -1} Cd stress without or with 1.5 mM Si. Plant growth of the Cd-tolerant cultivar was stimulated at the lower Cd level, but was decreased at the higher Cd level when plants were treated with Cd for one week. However, Plant growth was severely inhibited at both Cd levels as stress duration lasted for up to three weeks. Plant growth of the Cd-sensitive cultivar was severely inhibited at both Cd levels irrespective of Cd stress duration. Addition of Si increased shoot and root biomass of both cultivars at both Cd levels and decreased Cd uptake and root-to-shoot transport. Superoxide dismutase, catalase and ascorbate peroxidase activities decreased, but malondialdehyde and H{sub 2}O{sub 2} concentrations increased at the higher Cd level, which were counteracted by Si added. Ascorbic acid, glutathione and non-protein thiols concentrations increased at the higher Cd level, which were further intensified by addition of Si. The effects of Si and Cd on the antioxidant enzyme activity were further verified by isoenzyme analysis. Silicon was more effective in enhancing Cd tolerance in the Cd-tolerant cultivar than in the Cd-sensitive cultivar. It can be concluded that Si-enhanced Cd tolerance in B. chinensis is attributed mainly to Si-suppressed Cd uptake and root-to-shoot Cd transport and Si-enhanced antioxidant defense activity.

  1. Silicon-enhanced resistance to cadmium toxicity in Brassica chinensis L. is attributed to Si-suppressed cadmium uptake and transport and Si-enhanced antioxidant defense capacity

    International Nuclear Information System (INIS)

    Song Alin; Li Zhaojun; Zhang Jie; Xue Gaofeng; Fan Fenliang; Liang Yongchao

    2009-01-01

    A series of hydroponics experiments were performed to investigate roles of silicon (Si) in enhancing cadmium (Cd) tolerance in two pakchoi (Brassica chinensis L.) cultivars: i.e. cv. Shanghaiqing, a Cd-sensitive cultivar, and cv. Hangyoudong, a Cd-tolerant cultivar. Plants were grown under 0.5 and 5 mg Cd L -1 Cd stress without or with 1.5 mM Si. Plant growth of the Cd-tolerant cultivar was stimulated at the lower Cd level, but was decreased at the higher Cd level when plants were treated with Cd for one week. However, Plant growth was severely inhibited at both Cd levels as stress duration lasted for up to three weeks. Plant growth of the Cd-sensitive cultivar was severely inhibited at both Cd levels irrespective of Cd stress duration. Addition of Si increased shoot and root biomass of both cultivars at both Cd levels and decreased Cd uptake and root-to-shoot transport. Superoxide dismutase, catalase and ascorbate peroxidase activities decreased, but malondialdehyde and H 2 O 2 concentrations increased at the higher Cd level, which were counteracted by Si added. Ascorbic acid, glutathione and non-protein thiols concentrations increased at the higher Cd level, which were further intensified by addition of Si. The effects of Si and Cd on the antioxidant enzyme activity were further verified by isoenzyme analysis. Silicon was more effective in enhancing Cd tolerance in the Cd-tolerant cultivar than in the Cd-sensitive cultivar. It can be concluded that Si-enhanced Cd tolerance in B. chinensis is attributed mainly to Si-suppressed Cd uptake and root-to-shoot Cd transport and Si-enhanced antioxidant defense activity.

  2. Spiro-OMeTAD single crystals: Remarkably enhanced charge-carrier transport via mesoscale ordering

    KAUST Repository

    Shi, Dong; Qin, X.; Li, Yuan; He, Yao; Zhong, Cheng; Pan, Jun; Dong, H.; Xu, Wei; Li, T.; Hu, W.; Bredas, Jean-Luc; Bakr, Osman

    2016-01-01

    bottleneck for advancing cell efficiencies. We devised an antisolvent crystallization strategy to grow single crystals of spiro-OMeTAD, which allowed us to experimentally elucidate its molecular packing and transport properties. Electronic structure

  3. Intelligent products for enhancing the utilization of tracking technology in transportation

    NARCIS (Netherlands)

    Meyer, Gerben G.; Buijs, Paul; Szirbik, Nick B.; Wortmann, J.C.

    2014-01-01

    Purpose – Many transportation companies struggle to effectively utilize the information provided by tracking technology for performing operational control. The research as presented in this paper aims to identify the problems underlying the inability to utilize tracking technology within this

  4. Carrier Transport Enhancement in Conjugated Polymers through Interfacial Self-Assembly of Solution-State Aggregates

    KAUST Repository

    Zhao, Kui; Khan, Hadayat Ullah; Li, Ruipeng; Hu, Hanlin; Amassian, Aram

    2016-01-01

    and extension of the conjugated backbone of the polymer which clearly translate to significant improvements of carrier transport at the semiconductor-dielectric interface in organic thin film transistors. This study points to opportunities in combining

  5. Enhancing Transportation Equity Analysis for Long Range Planning and Decision Making

    OpenAIRE

    Bills, Tierra Suzan

    2013-01-01

    Metropolitan Planning Organizations (MPOs) regularly perform equity analyses for their long-range transportation plans, as this is required by Environmental Justice regulations. These regional-level plans may propose hundreds of transportation infrastructure and policy changes (e.g. highway and transit extensions, fare changes, pricing schemes, etc.) as well as land-use policy changes. The challenge is to assess the distribution of impacts from all the proposed changes across different popula...

  6. Environmental and thermodynamic evaluation of CO2 capture, transport and storage with and without enhanced resource recovery

    International Nuclear Information System (INIS)

    Iribarren, Diego; Petrakopoulou, Fontina; Dufour, Javier

    2013-01-01

    This study evaluates the environmental and thermodynamic performance of six coal-fired power plants with CO 2 capture and storage. The technologies examined are post-combustion capture using monoethanolamine, membrane separation, cryogenic fractionation and pressure swing adsorption, pre-combustion capture through coal gasification, and capture performing conventional oxy-fuel combustion. The incorporation of CO 2 capture is evaluated both on its own and in combination with CO 2 transport and geological storage, with and without beneficial use. Overall, we find that pre-combustion CO 2 capture and post-combustion through membrane separation present relatively low life-cycle environmental impacts and high exergetic efficiencies. When accounting for transport and storage, the environmental impacts increase and the efficiencies decrease. However, a better environmental performance can be achieved for CO 2 capture, transport and storage when incorporating beneficial use through enhanced oil recovery. The performance with enhanced coal-bed methane recovery, on the other hand, depends on the impact categories evaluated. The incorporation of methane recovery results in a better thermodynamic performance, when compared to the incorporation of oil recovery. The cumulative energy demand shows that the integration of enhanced resource recovery strategies is necessary to attain favourable life-cycle energy balances. - Highlights: ► Evaluation of six different CO 2 capture technologies for coal-fired power plants. ► Calculation of life-cycle environmental impacts and exergetic efficiencies. ► Suitability of post-combustion capture with membrane separation. ► Suitability of pre-combustion capture through coal gasification. ► Improved performance when incorporating enhanced resource recovery

  7. Energy gap and upper critical field of the new magnetic superconductor Mo3Sb7 found by the Andreev reflection method

    International Nuclear Information System (INIS)

    Dmitriev, V M; Rybaltchenko, L F; Ishchenko, L A; Khristenko, E V; Bukowski, Z; Troc, R

    2006-01-01

    We present the data of the point contact (PC) Andreev-reflection measurements on the new paramagnetic superconductor Mo 3 Sb 7 , which were used for finding the energy gap Δ and upper critical field H c2 for this compound. The maximum gap value, reduced to the zero temperature via the Bardeen-Cooper-Schrieffer (BCS) theory, turned out to be Δ (0) ≅ 0.32 meV, which is slightly smaller than that expected from the BCS theory, Δ BCS (0) ≅ 0.35 meV. The temperature dependence of the gap obeys the BCS theory approximately. The H c2 (0) value of about 16.5 kOe was obtained from fitting the experimental data to the conventional H(T) dependence, which is quadratic in temperature. This value is in close agreement with the result from magnetization measurements of 17.2 kOe

  8. Spiro-OMeTAD single crystals: Remarkably enhanced charge-carrier transport via mesoscale ordering

    KAUST Repository

    Shi, Dong

    2016-04-15

    We report the crystal structure and hole-transport mechanism in spiro-OMeTAD [2,2′,7,7′-tetrakis(N,N-di-p-methoxyphenyl-amine)9,9′-spirobifluorene], the dominant hole-transporting material in perovskite and solid-state dye-sensitized solar cells. Despite spiro-OMeTAD’s paramount role in such devices, its crystal structure was unknown because of highly disordered solution-processed films; the hole-transport pathways remained ill-defined and the charge carrier mobilities were low, posing a major bottleneck for advancing cell efficiencies. We devised an antisolvent crystallization strategy to grow single crystals of spiro-OMeTAD, which allowed us to experimentally elucidate its molecular packing and transport properties. Electronic structure calculations enabled us to map spiro-OMeTAD’s intermolecular charge-hopping pathways. Promisingly, single-crystal mobilities were found to exceed their thin-film counterparts by three orders of magnitude. Our findings underscore mesoscale ordering as a key strategy to achieving breakthroughs in hole-transport material engineering of solar cells.

  9. EGCG Enhances Cisplatin Sensitivity by Regulating Expression of the Copper and Cisplatin Influx Transporter CTR1 in Ovary Cancer.

    Directory of Open Access Journals (Sweden)

    Xuemin Wang

    Full Text Available Cisplatin is one of the first-line platinum-based chemotherapeutic agents for treatment of many types of cancer, including ovary cancer. CTR1 (copper transporter 1, a transmembrane solute carrier transporter, has previously been shown to increase the cellular uptake and sensitivity of cisplatin. It is hypothesized that increased CTR1 expression would enhance the sensitivity of cancer cells to cisplatin (cDDP. The present study demonstrates for the first time that (--epigallocatechin-3-gallate (EGCG, a major polyphenol from green tea, can enhance CTR1 mRNA and protein expression in ovarian cancer cells and xenograft mice. EGCG inhibits the rapid degradation of CTR1 induced by cDDP. The combination of EGCG and cDDP increases the accumulation of cDDP and DNA-Pt adducts, and subsequently enhances the sensitivity of ovarian cancer SKOV3 and OVCAR3 cells to the chemotherapeutic agent. In the OVCAR3 ovarian cancer xenograft nude mice model, the combination of the lower concentration of cDDP and EGCG strongly repressed the tumor growth and exhibited protective effect on the nephrotoxicity induced by cisplatin. Overall, these findings uncover a novel chemotherapy mechanism of EGCG as an adjuvant for the treatment of ovarian cancer.

  10. ENHANCING MOBILITY OF THE ELDERLY IN SUB-SAHARAN AFRICA CITIES THROUGH IMPROVED PUBLIC TRANSPORTATION

    Directory of Open Access Journals (Sweden)

    B. Olufemi ODUFUWA

    2006-01-01

    This paper analyzed the mobility of the elderly from the provision of public transport perspective and using mobility indicators-mean number of trips, time of travel, travel mode, accessibility and confortability of travel modes. The result shows that the available public transports in Nigeria cities are neither accessible nor convenient for the ageing population. As a result of economic hardship of the Nation for instance, most of the ageing population have no access to private means of mobility and thus they are increasingly dependent on the available public transport to meet their travel needs. Other findings reveals that the elderly makes more trips but with a selective time of travel. Nevertheless, the environmental emissions as well as exposure to traffic accident and long length of travel as a result of frequent traffic congestion have gross implications on the quality of life of the elderly.

  11. Ginsenoside Rg1 enhances lymphatic transport of intrapulmonary silica via VEGF-C/VEGFR-3 signaling in silicotic rats.

    Science.gov (United States)

    Yu, Jie; Mao, Lijun; Guan, Li; Zhang, Yanlin; Zhao, Jinyuan

    2016-03-25

    Ginsenoside Rg1, extracted mainly from Panax ginseng, has been shown to exert strong pro-angiogenic activities in vivo. But it is unclear whether ginsenoside Rg1 could promote lung lymphangiogenesis to improve lymphatic transport of intrapulmonary silica in silicotic rats. Here we investigated the effect of ginsenoside Rg1 on lymphatic transport of silica during experimental silicosis, and found that ginsenoside Rg1 treatment significantly raised the silicon content in tracheobronchial lymph nodes and serum to reduce the silicon level in lung interstitium, meanwhile increased pulmonary lymphatic vessel density by enhancing the protein and mRNA expressions of vascular endothelial growth factor-C (VEGF-C) and vascular endothelial growth factor receptor-3 (VEGFR-3). The stimulative effect of ginsenoside Rg1 on lymphatic transport of silica was actively correlated with its pro-lymphangiogenic identity. And VEGFR-3 inhibitor SAR131675 blocked these above effects of ginsenoside Rg1. These findings suggest that ginsenoside Rg1 exhibits good protective effect against lung burden of silica during experimental silicosis through improving lymphatic transport of intrapulmonary silica, which is potentially associated with the activation of VEGF-C/VEGFR-3 signaling pathway. Copyright © 2016 Elsevier Inc. All rights reserved.

  12. Enhanced safety margins during wet transport of irradiated fuel by catalytic recombination of radiolysis hydrogen and oxygen

    International Nuclear Information System (INIS)

    Spencer, J.T.; Bankhead, M.; Hodge, N.A.

    2004-01-01

    BNFL has developed and tested a new method for use in wet transport of irradiated fuel. The method uses a catalyst to recombine the hydrogen and oxygen produced from radiolysis. The catalyst is installed in the nitrogen ullage gas region. It has twin benefits as it eliminates a gas mixture that could, in principle, exceed the safe target levels set to ensure safety during Transport, and it also reduces overall gas pressure. Pure water radiolysis predictions, from experiment and theory, indicate very low levels of hydrogen and oxygen generation. BNFL's historic experience is that in some transport packages it is possible to produce higher levels of hydrogen and oxygen. This drives the need to improve on our existing ullage gas remediation technology. Our studies of the radiolysis science and our flask data suggest it is the interaction of the liquors and material surfaces that is giving rise to the enhanced levels of hydrogen and/or oxygen. This technical paper demonstrates the performance of the recombiner catalyst under normal and extreme conditions of transport. The paper will present experimental data that shows the recombiner catalyst working to manage the hydrogen and oxygen levels

  13. Can clouds enhance long-range transport of low volatile, ionizable and surface-active chemicals?

    DEFF Research Database (Denmark)

    Franco, Antonio; Trapp, Stefan

    2011-01-01

    Atmospheric partitioning and transport of low volatile organic compounds is strongly influenced by the presence of water (e.g. clouds) and its deposition velocity (e.g. rainfall, snow). It was identified that the assumption of continuous rainfall underestimates the residence time and the transport....... The longer residence time predicted for some compounds in the LMT is due to the capacity of clouds to sorb non-volatile molecules in the liquid water and at the interface of cloud droplets. The efficiency of wet deposition to remove low volatile organic pollutants from the atmosphere is limited primarily...

  14. Transport properties of field effect transistors with randomly networked single walled carbon nanotubes grown by plasma enhanced chemical vapour deposition

    International Nuclear Information System (INIS)

    Kim, Un Jeong; Park, Wanjun

    2009-01-01

    The transport properties of randomly networked single walled carbon nanotube (SWNT) transistors with different channel lengths of L c = 2-10 μm were investigated. Randomly networked SWNTs were directly grown for the two different densities of ρ ∼ 25 μm -2 and ρ ∼ 50 μm -2 by water plasma enhanced chemical vapour deposition. The field effect transport is governed mainly by formation of the current paths that is related to the nanotube density. On the other hand, the off-state conductivity deviates from linear dependence for both nanotube density and channel length. The field effect mobility of holes is estimated as 4-13 cm 2 V -1 s -1 for the nanotube transistors based on the simple MOS theory. The mobility is increased for the higher density without meaningful dependence on the channel lengths.

  15. Improving the Value Chain of Biofuel Manufacturing Operations by Enhancing Coproduct Transportation and Logistics

    Science.gov (United States)

    Biofuels, including corn-based ethanol, can partially meet the increasing demand for transportation fuels. The production of ethanol in the U.S. has dramatically increased; so too has the quantity of manufacturing coproducts. These nonfermentable residues (i.e., proteins, fibers, oils) are sold as...

  16. How tides and waves enhance aeolian sediment transport at the sand motor mega-nourishment

    NARCIS (Netherlands)

    Hoonhout, B.M.; Luijendijk, A.P.; de Vries, S.; Roelvink, D.; Aagaard, T.; Deigaard, R.; Fuhrman, D.

    2017-01-01

    Expanding knowledge concerning the close entanglement between subtidal and subaerial processes in coastal environments initiated the development of the open-source Windsurf modeling framework that enables us to simulate
    multi-fraction sediment transport due to subtidal and subaerial processes

  17. Assessment of the Ehlanzeni District health transport and logistics function: Enhancing rural healthcare delivery systems

    CSIR Research Space (South Africa)

    Mashiri, MAM

    2009-07-01

    Full Text Available This paper seeks to establish a baseline against which to assess the impacts of the ‘Ehlanzeni District Health Transport Function’ for the district’s healthcare service delivery output, and by extension, health and welfare outcomes. The main...

  18. Local synaptic signaling enhances the stochastic transport of motor-driven cargo in neurons

    KAUST Repository

    Newby, Jay; Bressloff, Paul C

    2010-01-01

    The tug-of-war model of motor-driven cargo transport is formulated as an intermittent trapping process. An immobile trap, representing the cellular machinery that sequesters a motor-driven cargo for eventual use, is located somewhere within a

  19. Enhanced transport phenomena in CO2 sequestration and CO2 EOR

    NARCIS (Netherlands)

    Farajzadeh, R.

    2009-01-01

    The results of this thesis give insight into the (mass)-transfer during flow of gases, especially CO2, in various gas-liquid systems. A number of experiments was performed to investigate the transport phenomena through interfaces with and without surfactant monolayers. The observed phenomena have

  20. Applying GPS to enhance understanding of transport-related physical activity.

    Science.gov (United States)

    Duncan, Mitch J; Badland, Hannah M; Mummery, W Kerry

    2009-09-01

    The purpose of the paper is to review the utility of the global positioning system (GPS) in the study of health-related physical activity. The paper draws from existing literature to outline the current work performed using GPS to examine transport-related physical activity, with a focus on the relative utility of the approach when combined with geographic information system (GIS) and other data sources including accelerometers. The paper argues that GPS, especially when used in combination with GIS and accelerometery, offers great promise in objectively measuring and studying the relationship of numerous environmental attributes to human behaviour in terms of physical activity and transport-related activity. Limitations to the use of GPS for the purpose of monitoring health-related physical activity are presented, and recommendations for future avenues of research are discussed.

  1. Enhancement of charge-transport characteristics in polymeric films using polymer brushes

    DEFF Research Database (Denmark)

    Whiting, G.L.; Snaith, H.J.; Khodabakhsh, S.

    2006-01-01

    We show that charge-transporting polymer chains in the brush conformation can be synthesized from a variety of substrates of interest, displaying a high degree of stretching and showing up to a 3 orders of magnitude increase in current density normal to the substrate as compared with a spin......-coated film. These nanostructured polymeric films may prove to be suitable for electronic devices based on molecular semiconductors as current fabrication techniques often provide little control over film structure....

  2. Leveraging Service Oriented Architecture to Enhance Information Sharing for Surface Transportation Security

    Science.gov (United States)

    2008-09-01

    Fire and Emergency Management Services, Suffolk County Sheriff’s Department, the U.S. Attorney’s Office, the Bureau of Alcohol, Tobacco and Firearms...mass transit services. These include express and regular bus service, a downtown Skyway monorail , a trolley service and the Stadium Shuttle for various...safety related incidents rather than security, including transportation disruptions due to derailments, accidents, fires , hazardous materials spills

  3. G3.5 PAMAM dendrimers enhance transepithelial transport of SN38 while minimizing gastrointestinal toxicity.

    Science.gov (United States)

    Goldberg, Deborah S; Vijayalakshmi, Nirmalkumar; Swaan, Peter W; Ghandehari, Hamidreza

    2011-03-30

    Poly(amido amine) (PAMAM) dendrimers have shown promise in oral drug delivery. Conjugation of SN38 to PAMAM dendrimers has the potential to improve its oral absorption while minimizing gastrointestinal toxicity. In this work we evaluated G3.5 PAMAM dendrimer-SN38 conjugates with ester-linked glycine and β-alanine spacers for their suitability in oral therapy of hepatic colorectal cancer metastases. G3.5-βAlanine-SN38 was mostly stable while G3.5-Glycine-SN38 showed 10%, 20%, and 56% SN38 release in simulated gastric, intestinal and liver environments for up to 6, 24 and 48 hours, respectively. Short-term treatment of Caco-2 cells with G3.5-SN38 conjugates did not reduce cell viability, while comparable concentrations of SN38 caused significant cytotoxicity. G3.5-Glycine-SN38 and G3.5-βAlanine-SN38 showed IC₅₀ values of 0.60 and 3.59 μM, respectively, in HT-29 cells treated for 48 h, indicating the efficacy of the drug delivery system in colorectal cancer cells with longer incubation time. Both conjugates increased SN38 transepithelial transport compared to the free drug. Transport of G3.5-Glycine-SN38 was highly concentration-dependent whereas transport of G3.5-βAlanine-SN38 was concentration-independent, highlighting the influence of drug loading and spacer chemistry on transport mechanism. Together these results show that PAMAM dendrimers have the potential to improve the oral bioavailability of potent anti-cancer drugs. Copyright © 2010 Elsevier B.V. All rights reserved.

  4. Enhanced transport of zerovalent iron nanoparticles in saturated porous media by guar gum

    International Nuclear Information System (INIS)

    Tiraferri, Alberto; Sethi, Rajandrea

    2009-01-01

    In order to ensure adequate mobility of zerovalent iron nanoparticles in natural aquifers, the use of a stabilizing agent is necessary. Polymers adsorbed on the nanoparticle surface will give rise to electrosteric stabilization and will decrease attachment to the surface soil grains. Water saturated sand-packed columns were used in this study to investigate the transport of iron nanoparticle suspensions, bare or modified with the green polymer guar gum. The suspensions were prepared at 154 mg/L particle concentration and 0.5 g/L polymer concentration. Transport experiments were conducted by varying the ionic strength, ionic composition, and approach velocity of the fluid. Nanoparticle deposition rates, attachment efficiencies, and travel distances were subsequently calculated based on the classical particle filtration theory. It was found that bare iron nanoparticles are basically immobile in sandy porous media. In contrast, guar gum is able to ensure significant nanoparticle transport at the tested conditions, regardless of the chemistry of the solution. Attachment efficiency values for guar gum-coated nanoparticles under the various conditions tested were smaller than 0.066. Although the calculated travel distances may not prove satisfactory for field application, the investigation attested the promising role of guar gum to ensure mobility of iron nanoparticles in the subsurface environment.

  5. Quality performance-based training enhances safe and effective transport operations

    International Nuclear Information System (INIS)

    McCall, D.L.

    1993-01-01

    If the hazardous materials transportation industry is to reduce human error, reduce accidents, and improve its public image, there must be assurance that transportation personnel are properly trained and qualified to perform their jobs in a safe and efficient manner. This training must make them intimately aware of the hazards and risks associated with transport activities, ensure understanding of responsibilities and liabilities unique to their job, and ensure that they can competently perform functional duties vital to safety. To ensure that trained and qualified personnel are on the job, it is essential that the training be performance-based and require trainees to demonstrate functional proficiency. Performance-based training has proven to be a highly effective means of ensuring personnel are qualified to conduct their assignments safely and efficiently. This training is designed around the basic premise that training must be provided that supplies the information necessary for each worker to perform their assigned duties at a predetermined and acceptable level of expertise and skill. (J.P.N.)

  6. Multigap superconductivity and strong electron-boson coupling in Fe-based superconductors: a point-contact Andreev-reflection study of Ba(Fe(1-x)Co(x))2As2 single crystals.

    Science.gov (United States)

    Tortello, M; Daghero, D; Ummarino, G A; Stepanov, V A; Jiang, J; Weiss, J D; Hellstrom, E E; Gonnelli, R S

    2010-12-03

    Directional point-contact Andreev-reflection measurements in Ba(Fe(1-x)Co(x))2As2 single crystals (T(c) = 24.5 K) indicate the presence of two superconducting gaps with no line nodes on the Fermi surface. The point-contact Andreev-reflection spectra also feature additional structures related to the electron-boson interaction, from which the characteristic boson energy Ω(b)(T) is obtained, very similar to the spin-resonance energy observed in neutron scattering experiments. Both the gaps and the additional structures can be reproduced within a three-band s ± Eliashberg model by using an electron-boson spectral function peaked at Ω(0) = 12 meV ≃ Ω(b)(0).

  7. Charge carrier transport and collection enhancement of copper indium diselenide photoactive nanoparticle-ink by laser crystallization

    Energy Technology Data Exchange (ETDEWEB)

    Nian, Qiong; Cheng, Gary J., E-mail: gjcheng@purdue.edu [Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47906 (United States); School of Industrial Engineering, Purdue University, West Lafayette, Indiana 47906 (United States); Zhang, Martin Y. [School of Industrial Engineering, Purdue University, West Lafayette, Indiana 47906 (United States); Wang, Yuefeng [Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47906 (United States); School of Materials Engineering, Purdue University, West Lafayette, Indiana 47906 (United States); Das, Suprem R.; Bhat, Venkataprasad S. [Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47906 (United States); Huang, Fuqiang [Shanghai Institute of Ceramics, Chinese Academy of Science, Shanghai 200050 (China)

    2014-09-15

    There has been increasing needs for cost-effective and high performance thin film deposition techniques for photovoltaics. Among all deposition techniques, roll-to-roll printing of nanomaterials has been a promising method. However, the printed thin film contains many internal imperfections, which reduce the charge-collection performance. Here, direct pulse laser crystallization (DPLC) of photoactive nanoparticles-inks is studied to meet this challenge. In this study, copper indium selenite (CIS) nanoparticle-inks is applied as an example. Enhanced crystallinity, densified structure in the thin film is resulted after DLPC under optimal conditions. It is found that the decreased film internal imperfections after DPLC results in reducing scattering and multi-trapping effects. Both of them contribute to better charge-collection performance of CIS absorber material by increasing extended state mobility and carrier lifetime, when carrier transport and kinetics are coupled. Charge carrier transport was characterized after DPLC, showing mobility increased by 2 orders of magnitude. Photocurrent under AM1.5 illumination was measured and shown 10 times enhancement of integrated power density after DPLC, which may lead to higher efficiency in photo-electric energy conversion.

  8. The enhanced spin-polarized transport behaviors through cobalt benzene-porphyrin-benzene molecular junctions: the effect of functional groups

    Science.gov (United States)

    Cheng, Jue-Fei; Zhou, Liping; Wen, Zhongqian; Yan, Qiang; Han, Qin; Gao, Lei

    2017-05-01

    The modification effects of the groups amino (NH2) and nitro (NO2) on the spin polarized transport properties of the cobalt benzene-porphyrin-benzene (Co-BPB) molecule coupled to gold (Au) nanowire electrodes are investigated by the nonequilibrium Green’s function method combined with the density functional theory. The calculation results show that functional groups can lead to the significant spin-filter effect, enhanced low-bias negative differential resistance (NDR) behavior and novel reverse rectifying effect in Co-BPB molecular junction. The locations and types of functional groups have distinct influences on spin-polarized transport performances. The configuration with NH2 group substituting H atom in central porphyrin ring has larger spin-down current compared to that with NO2 substitution. And Co-BPB molecule junction with NH2 group substituting H atom in side benzene ring shows reverse rectifying effect. Detailed analyses confirm that NH2 and NO2 group substitution change the spin-polarized transferred charge, which makes the highest occupied molecular orbitals (HOMO) of spin-down channel of Co-BPB closer to the Fermi level. And the shift of HOMO strengthens the spin-polarized coupling between the molecular orbitals and the electrodes, leading to the enhanced spin-polarized behavior. Our findings might be useful in the design of multi-functional molecular devices in the future.

  9. Electrohydrodynamic fibrillation governed enhanced thermal transport in dielectric colloids under a field stimulus.

    Science.gov (United States)

    Dhar, Purbarun; Maganti, Lakshmi Sirisha; Harikrishnan, A R

    2018-05-30

    Electrorheological (ER) fluids are known to exhibit enhanced viscous effects under an electric field stimulus. The present article reports the hitherto unreported phenomenon of greatly enhanced thermal conductivity in such electro-active colloidal dispersions in the presence of an externally applied electric field. Typical ER fluids are synthesized employing dielectric fluids and nanoparticles and experiments are performed employing an in-house designed setup. Greatly augmented thermal conductivity under a field's influence was observed. Enhanced thermal conduction along the fibril structures under the field effect is theorized as the crux of the mechanism. The formation of fibril structures has also been experimentally verified employing microscopy. Based on classical models for ER fluids, a mathematical formalism has been developed to predict the propensity of chain formation and statistically feasible chain dynamics at given Mason numbers. Further, a thermal resistance network model is employed to computationally predict the enhanced thermal conduction across the fibrillary colloid microstructure. Good agreement between the mathematical model and the experimental observations is achieved. The domineering role of thermal conductivity over relative permittivity has been shown by proposing a modified Hashin-Shtrikman (HS) formalism. The findings have implications towards better physical understanding and design of ER fluids from both 'smart' viscoelastic as well as thermally active materials points of view.

  10. OPTIMISATION OF BUFFER SIZE FOR ENHANCING QOS OF VIDEO TRAFFIC USING CROSS LAYERED HYBRID TRANSPORT LAYER PROTOCOL APPROACH

    Directory of Open Access Journals (Sweden)

    S. Matilda

    2011-03-01

    Full Text Available Video streaming is gaining importance, with the wide popularity of multimedia rich applications in the Internet. Video streams are delay sensitive and require seamless flow for continuous visualization. Properly designed buffers offer a solution to queuing delay. The diagonally opposite QoS metrics associated with video traffic poses an optimization problem, in the design of buffers. This paper is a continuation of our previous work [1] and deals with the design of buffers. It aims at finding the optimum buffer size for enhancing QoS offered to video traffic. Network-centric QoS provisioning approach, along with hybrid transport layer protocol approach is adopted, to arrive at an optimum size which is independent of RTT. In this combinational approach, buffers of routers and end devices are designed to satisfy the various QoS parameters at the transport layer. OPNET Modeler is used to simulate environments for testing the design. Based on the results of simulation it is evident that the hybrid transport layer protocol approach is best suited for transmitting video traffic as it supports the economical design.

  11. Enhance the sustainability of private land transport system at Ayer Keroh, Melaka

    Science.gov (United States)

    Loo, Heoy Shin; Chew, Boon Cheong; Hamid, Syaiful Rizal; Yang, Yu Xin Ou

    2017-03-01

    Ayer Keroh Toll that under the administration of Hang Tuah Jaya Municipal Council (HTJMC) is the main entrance for the people to enter to the city from North-South Expressway. This situation causes congestion to happen in this area especially during weekend and holiday and lead to air pollution. Hence, it is important to solve this problem beginning with the transport system and brings the city toward the sustainable way by learning the foreign city experience. In this research, the researchers start to revise the case study from foreign city councils on what and how they improve their cities transport system in term of sustainability. There are total of 17 case studies been studied including the cities that recognize with Sustainable Transport Award (STA) and other special activity and event that held worldwide. These cases studied are merged with the behavioral modification. There are four methods of changing behavior: positive reinforcement, negative reinforcement, punishment and extinction. Besides, the data from the administrative staff (HTJMC's officer) also important to success the planning. There are 16 officers that involved in this research and the data that obtained is used as the primary data resources. By knowing the behavioral modification and suggestion that brought by each case studies, the researchers will conclude whether the solution practicable in Ayer Keroh, Melaka or not. Throughout the research, the researchers can conclude that the not all the foreign experience is practical in Ayer, Keroh, Melaka due to the problem of weather, culture and technology that available in the city. The experience from foreign city cannot be exactly to implement in the city but need to redesign to match culture in the city.

  12. Percolated microstructures for multi-modal transport enhancement in porous active materials

    Energy Technology Data Exchange (ETDEWEB)

    McKay, Ian Salmon; Yang, Sungwoo; Wang, Evelyn N.; Kim, Hyunho

    2018-03-13

    A method of forming a composite material for use in multi-modal transport includes providing three-dimensional graphene having hollow channels, enabling a polymer to wick into the hollow channels of the three-dimensional graphene, curing the polymer to form a cured three-dimensional graphene, adding an active material to the cured three-dimensional graphene to form a composite material, and removing the polymer from within the hollow channels. A composite material formed according to the method is also provided.

  13. Stakeholder Transportation Scorecard: Reviewing Nevada's Recommendations for Enhancing the Safety and Security of Nuclear Waste Shipments - 13518

    Energy Technology Data Exchange (ETDEWEB)

    Dilger, Fred C. [Black Mountain Research, Henderson, NV 81012 (United States); Ballard, James D. [Department of Sociology, California State University, Northridge, CA 91330 (United States); Halstead, Robert J. [State of Nevada Agency for Nuclear Projects, Carson City, NV 80906 (United States)

    2013-07-01

    As a primary stakeholder in the Yucca Mountain program, the state of Nevada has spent three decades examining and considering national policy regarding spent nuclear fuel and high-level radioactive waste transportation. During this time, Nevada has identified 10 issues it believes are critical to ensuring the safety and security of any spent nuclear fuel transportation program, and achieving public acceptance. These recommendations are: 1) Ship the oldest fuel first; 2) Ship mostly by rail; 3) Use dual-purpose (transportable storage) casks; 4) Use dedicated trains for rail shipments; 5) Implement a full-scale cask testing program; 6) Utilize a National Environmental Policy Act (NEPA) process for the selection of a new rail spur to the proposed repository site; 7) Implement the Western Interstate Energy Board (WIEB) 'straw man' process for route selection; 8) Implement Section 180C assistance to affected States, Tribes and localities through rulemaking; 9) Adopt safety and security regulatory enhancements proposed states; and 10) Address stakeholder concerns about terrorism and sabotage. This paper describes Nevada's proposals in detail and examines their current status. The paper describes the various forums and methods by which Nevada has presented its arguments and sought to influence national policy. As of 2012, most of Nevada's recommendations have been adopted in one form or another, although not yet implemented. If implemented in a future nuclear waste program, the State of Nevada believes these recommendations would form the basis for a successful national transportation plan for shipments to a geologic repository and/or centralized interim storage facility. (authors)

  14. Stakeholder Transportation Scorecard: Reviewing Nevada's Recommendations for Enhancing the Safety and Security of Nuclear Waste Shipments - 13518

    International Nuclear Information System (INIS)

    Dilger, Fred C.; Ballard, James D.; Halstead, Robert J.

    2013-01-01

    As a primary stakeholder in the Yucca Mountain program, the state of Nevada has spent three decades examining and considering national policy regarding spent nuclear fuel and high-level radioactive waste transportation. During this time, Nevada has identified 10 issues it believes are critical to ensuring the safety and security of any spent nuclear fuel transportation program, and achieving public acceptance. These recommendations are: 1) Ship the oldest fuel first; 2) Ship mostly by rail; 3) Use dual-purpose (transportable storage) casks; 4) Use dedicated trains for rail shipments; 5) Implement a full-scale cask testing program; 6) Utilize a National Environmental Policy Act (NEPA) process for the selection of a new rail spur to the proposed repository site; 7) Implement the Western Interstate Energy Board (WIEB) 'straw man' process for route selection; 8) Implement Section 180C assistance to affected States, Tribes and localities through rulemaking; 9) Adopt safety and security regulatory enhancements proposed states; and 10) Address stakeholder concerns about terrorism and sabotage. This paper describes Nevada's proposals in detail and examines their current status. The paper describes the various forums and methods by which Nevada has presented its arguments and sought to influence national policy. As of 2012, most of Nevada's recommendations have been adopted in one form or another, although not yet implemented. If implemented in a future nuclear waste program, the State of Nevada believes these recommendations would form the basis for a successful national transportation plan for shipments to a geologic repository and/or centralized interim storage facility. (authors)

  15. Enhanced electrical transport and thermoelectric properties in Ni doped Cu3SbSe4

    Science.gov (United States)

    Kumar, Aparabal; Dhama, P.; Das, Anish; Sarkar, Kalyan Jyoti; Banerji, P.

    2018-05-01

    In this study, we report the enhanced thermoelectric performance of Cu3SbSe4 by Ni doping at Cu site. Cu3-xNixSbSe4 (x = 0, 0.01, 0.03, 0.05) were prepared by melt growth, ball milling followed by spark plasma sintering. Structural characterization, phase analysis and surface morphology were carried out using X-ray diffraction, field emission scanning electron microscopy and energy dispersive X-ray spectroscopy. Electrical and thermal properties of all the samples were investigated in the temperature range 300 - 650 K. Decrease in electrical resistivity with Ni doping due to increase in carrier concentration with enhanced Seebeck coefficient via increase in density of state near the Fermi level gives a remarkably high power factor. At the same time, thermal conductivity was found to decrease due to increased carrier-phonon scattering and acoustic phonon scattering. Consequently, a remarkable enhancement in the thermoelectric figure of merit (ZT˜ 0.65) of Cu3-xNixSbSe4 was achieved for x = 0.01 sample. Thus, Ni doping is an effective approach to improve the efficiency of Cu3SbSe4.

  16. Fusarium oxysporum volatiles enhance plant growth via affecting auxin transport and signaling

    Directory of Open Access Journals (Sweden)

    Vasileios eBitas

    2015-11-01

    Full Text Available Volatile organic compounds (VOCs have well-documented roles in plant-plant communication and directing animal behavior. In this study, we examine the less understood roles of VOCs in plant-fungal relationships. Phylogenetically and ecologically diverse strains of Fusarium oxysporum, a fungal species complex that often resides in the rhizosphere of assorted plants, produce volatile compounds that augment shoot and root growth of Arabidopsis thaliana and tobacco. Growth responses of A. thaliana hormone signaling mutants and expression patterns of a GUS reporter gene under the auxin-responsive DR5 promoter supported the involvement of auxin signaling in F. oxysporum volatile-mediated growth enhancement. In addition, 1-naphthylthalamic acid, an inhibitor of auxin efflux, negated F. oxysporum volatile-mediated growth enhancement in both plants. Comparison of the profiles of volatile compounds produced by F. oxysporum strains that differentially affected plant growth suggests that the relative compositions of both growth inhibitory and stimulatory compounds may determine the degree of plant growth enhancement. Volatile-mediated signaling between fungi and plants may represent a potentially conserved, yet mostly overlooked, mechanism underpinning plant-fungus interactions and fungal niche adaption.

  17. Directed transport by surface chemical potential gradients for enhancing analyte collection in nanoscale sensors.

    Science.gov (United States)

    Sitt, Amit; Hess, Henry

    2015-05-13

    Nanoscale detectors hold great promise for single molecule detection and the analysis of small volumes of dilute samples. However, the probability of an analyte reaching the nanosensor in a dilute solution is extremely low due to the sensor's small size. Here, we examine the use of a chemical potential gradient along a surface to accelerate analyte capture by nanoscale sensors. Utilizing a simple model for transport induced by surface binding energy gradients, we study the effect of the gradient on the efficiency of collecting nanoparticles and single and double stranded DNA. The results indicate that chemical potential gradients along a surface can lead to an acceleration of analyte capture by several orders of magnitude compared to direct collection from the solution. The improvement in collection is limited to a relatively narrow window of gradient slopes, and its extent strongly depends on the size of the gradient patch. Our model allows the optimization of gradient layouts and sheds light on the fundamental characteristics of chemical potential gradient induced transport.

  18. Dopant effects on charge transport to enhance performance of phosphorescent white organic light emitting diodes

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Liping; Chen, Jiangshan; Ma, Dongge, E-mail: mdg1014@ciac.ac.cn [State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Changchun 130022 (China)

    2015-11-07

    We compared the performance of phosphorescent white organic light emitting diodes (WOLEDs) with red-blue-green and green-blue-red sequent emissive layers. It was found that the influence of red and green dopants on electron and hole transport in emissive layers leads to the large difference in the efficiency of fabricated WOLEDs. This improvement mechanism is well investigated by the current density-voltage characteristics of single-carrier devices based on dopant doped emissive layers and the comparison of electroluminescent and photoluminescence spectra, and attributed to the different change of charge carrier transport by the dopants. The optimized device achieves a maximum power efficiency, current efficiency, and external quantum efficiency of 37.0 lm/W, 38.7 cd/A, and 17.7%, respectively, which are only reduced to 32.8 lm/W, 38.5 cd/A, and 17.3% at 1000 cd/m{sup 2} luminance. The critical current density is as high as 210 mA/cm{sup 2}. It can be seen that the efficiency roll-off in phosphorescent WOLEDs can be well improved by effectively designing the structure of emissive layers.

  19. The ABC transporter Rv1272c of Mycobacterium tuberculosis enhances the import of long-chain fatty acids in Escherichia coli.

    Science.gov (United States)

    Martin, Audrey; Daniel, Jaiyanth

    2018-02-05

    Mycobacterium tuberculosis (Mtb), which causes tuberculosis, is capable of accumulating triacylglycerol (TAG) by utilizing fatty acids from host cells. ATP-binding cassette (ABC) transporters are involved in transport processes in all organisms. Among the classical ABC transporters in Mtb none have been implicated in fatty acid import. Since the transport of fatty acids from the host cell is important for dormancy-associated TAG synthesis in the pathogen, mycobacterial ABC transporter(s) could potentially be involved in this process. Based on sequence identities with a bacterial ABC transporter that mediates fatty acid import for TAG synthesis, we identified Rv1272c, a hitherto uncharacterized ABC-transporter in Mtb that also shows sequence identities with a plant ABC transporter involved in fatty acid transport. We expressed Rv1272c in E. coli and show that it enhances the import of radiolabeled fatty acids. We also show that Rv1272c causes a significant increase in the metabolic incorporation of radiolabeled long-chain fatty acids into cardiolipin, a tetra-acylated phospholipid, and phosphatidylglycerol in E. coli. This is the first report on the function of Rv1272c showing that it displays a long-chain fatty acid transport function. Copyright © 2018 Elsevier Inc. All rights reserved.

  20. Enhanced vapor transport in membrane distillation via functionalized carbon nanotubes anchored into electrospun nanofibres

    KAUST Repository

    An, Alicia Kyoungjin; Lee, Eui-Jong; Guo, Jiaxin; Jeong, Sanghyun; Lee, Jung Gil; Ghaffour, NorEddine

    2017-01-01

    To ascertain membrane distillation (MD) as an emerging desalination technology to meet the global water challenge, development of membranes with ideal material properties is crucial. Functionalized carbon nanotubes (CNTs) were anchored to nanofibres of electrospun membranes. Covalent modification and fluorination of CNTs improved their dispersibility and interfacial interaction with the polymer membrane, resulting in well-aligned CNTs inside crystalline fibres with superhydrophobicity. Consideration for the chemical/physical properties of the CNT composite membranes and calculation of their theoretical fluxes revealed the mechanism of MD: CNTs facilitated the repulsive force for Knudsen and molecular diffusions, reduced the boundary-layer effect in viscous flow, and assisted surface diffusion, allowing for fast vapor transport with anti-wetting. This study shows that the role of CNTs and an optimal composite ratio can be used to reduce the gap between theoretical and experimental approaches to desalination.

  1. Enhanced vapor transport in membrane distillation via functionalized carbon nanotubes anchored into electrospun nanofibres

    KAUST Repository

    An, Alicia Kyoungjin

    2017-01-30

    To ascertain membrane distillation (MD) as an emerging desalination technology to meet the global water challenge, development of membranes with ideal material properties is crucial. Functionalized carbon nanotubes (CNTs) were anchored to nanofibres of electrospun membranes. Covalent modification and fluorination of CNTs improved their dispersibility and interfacial interaction with the polymer membrane, resulting in well-aligned CNTs inside crystalline fibres with superhydrophobicity. Consideration for the chemical/physical properties of the CNT composite membranes and calculation of their theoretical fluxes revealed the mechanism of MD: CNTs facilitated the repulsive force for Knudsen and molecular diffusions, reduced the boundary-layer effect in viscous flow, and assisted surface diffusion, allowing for fast vapor transport with anti-wetting. This study shows that the role of CNTs and an optimal composite ratio can be used to reduce the gap between theoretical and experimental approaches to desalination.

  2. Internal Flow Simulation of Enhanced Performance Solid Rocket Booster for the Space Transportation System

    Science.gov (United States)

    Ahmad, Rashid A.; McCool, Alex (Technical Monitor)

    2001-01-01

    An enhanced performance solid rocket booster concept for the space shuttle system has been proposed. The concept booster will have strong commonality with the existing, proven, reliable four-segment Space Shuttle Reusable Solid Rocket Motors (RSRM) with individual component design (nozzle, insulator, etc.) optimized for a five-segment configuration. Increased performance is desirable to further enhance safety/reliability and/or increase payload capability. Performance increase will be achieved by adding a fifth propellant segment to the current four-segment booster and opening the throat to accommodate the increased mass flow while maintaining current pressure levels. One development concept under consideration is the static test of a "standard" RSRM with a fifth propellant segment inserted and appropriate minimum motor modifications. Feasibility studies are being conducted to assess the potential for any significant departure in component performance/loading from the well-characterized RSRM. An area of concern is the aft motor (submerged nozzle inlet, aft dome, etc.) where the altered internal flow resulting from the performance enhancing features (25% increase in mass flow rate, higher Mach numbers, modified subsonic nozzle contour) may result in increased component erosion and char. To assess this issue and to define the minimum design changes required to successfully static test a fifth segment RSRM engineering test motor, internal flow studies have been initiated. Internal aero-thermal environments were quantified in terms of conventional convective heating and discrete phase alumina particle impact/concentration and accretion calculations via Computational Fluid Dynamics (CFD) simulation. Two sets of comparative CFD simulations of the RSRM and the five-segment (IBM) concept motor were conducted with CFD commercial code FLUENT. The first simulation involved a two-dimensional axi-symmetric model of the full motor, initial grain RSRM. The second set of analyses

  3. Phase coherent transport in hybrid superconductor-topological insulator devices

    Science.gov (United States)

    Finck, Aaron

    2015-03-01

    Heterostructures of superconductors and topological insulators are predicted to host unusual zero energy bound states known as Majorana fermions, which can robustly store and process quantum information. Here, I will discuss our studies of such heterostructures through phase-coherent transport, which can act as a unique probe of Majorana fermions. We have extensively explored topological insulator Josephson junctions through SQUID and single-junction diffraction patterns, whose unusual behavior give evidence for low-energy Andreev bound states. In topological insulator devices with closely spaced normal and superconducting leads, we observe prominent Fabry-Perot oscillations, signifying gate-tunable, quasi-ballistic transport that can elegantly interact with Andreev reflection. Superconducting disks deposited on the surface of a topological insulator generate Aharonov-Bohm-like oscillations, giving evidence for unusual states lying near the interface between the superconductor and topological insulator surface. Our results point the way towards sophisticated interferometers that can detect and read out the state of Majorana fermions in topological systems. This work was done in collaboration with Cihan Kurter, Yew San Hor, and Dale Van Harlingen. We acknowledge funding from Microsoft Project Q.

  4. Coherent transport through interacting quantum dots

    International Nuclear Information System (INIS)

    Hiltscher, Bastian

    2012-01-01

    the linear-conductance regime. The second work deals with the ratio of coherent processes in transport through quantum dots. To this end, a quantum dot is embedded in one of the arms of an Aharonov-Bohm interferometer. In former theoretical as well as experimental works it has been observed that an important source of decoherence are cotunneling processes that flip the dot's spin. In order to elucidate the role of spin in more detail, we assume one of the leads to be ferromagnetic and the other one to be normal. The main motivations of our work are the two questions: (1) What fraction of the total current through a single-level quantum dot weakly coupled to the electrodes is coherent? (2) How and under which circumstances can this fraction be extracted from a current measurement in an Aharonov-Bohm setup? The measurable quantity in such an experiment is the magnetic-flux dependent ratio of the total current. It turns out that the answers of the two questions strongly depend on the dot level position, the polarization of the ferromagnet, and the transport direction. Especially the flux-dependent and the coherent ratios are not necessarily the same. The main motivation of the third work is to identify crossed Andreev reflection in quantum dots, that is, a Cooper pair splits into two single electrons, which are transferred into different quantum dots in one coherent process. We consider a setup, where two quantum dots are tunnel coupled to the same superconductor and each dot is additionally coupled to a normal conductor. In previous works a bias voltage has been applied between the superconductor and the normal conductors. Then, three processes sustain transport. Beside crossed Andreev reflection also local Andreev reflection, where both electrons of the Cooper pair tunnel into the same dot, and single-particle tunneling occur. This complicates the identification of crossed Andreev reflection. Therefore, we propose the transport mechanism of adiabatic pumping in the

  5. Coherent transport through interacting quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Hiltscher, Bastian

    2012-10-05

    the linear-conductance regime. The second work deals with the ratio of coherent processes in transport through quantum dots. To this end, a quantum dot is embedded in one of the arms of an Aharonov-Bohm interferometer. In former theoretical as well as experimental works it has been observed that an important source of decoherence are cotunneling processes that flip the dot's spin. In order to elucidate the role of spin in more detail, we assume one of the leads to be ferromagnetic and the other one to be normal. The main motivations of our work are the two questions: (1) What fraction of the total current through a single-level quantum dot weakly coupled to the electrodes is coherent? (2) How and under which circumstances can this fraction be extracted from a current measurement in an Aharonov-Bohm setup? The measurable quantity in such an experiment is the magnetic-flux dependent ratio of the total current. It turns out that the answers of the two questions strongly depend on the dot level position, the polarization of the ferromagnet, and the transport direction. Especially the flux-dependent and the coherent ratios are not necessarily the same. The main motivation of the third work is to identify crossed Andreev reflection in quantum dots, that is, a Cooper pair splits into two single electrons, which are transferred into different quantum dots in one coherent process. We consider a setup, where two quantum dots are tunnel coupled to the same superconductor and each dot is additionally coupled to a normal conductor. In previous works a bias voltage has been applied between the superconductor and the normal conductors. Then, three processes sustain transport. Beside crossed Andreev reflection also local Andreev reflection, where both electrons of the Cooper pair tunnel into the same dot, and single-particle tunneling occur. This complicates the identification of crossed Andreev reflection. Therefore, we propose the transport mechanism of adiabatic pumping in

  6. Instability, Turbulence, and Enhanced Transport in Collisionless Black-Hole Accretion Flows

    Science.gov (United States)

    Kunz, Matthew

    Many astrophysical plasmas are so hot and diffuse that the collisional mean free path is larger than the system size. Perhaps the best examples of such systems are lowluminosity accretion flows onto black holes such as Sgr A* at the center of our own Galaxy, or M87 in the Virgo cluster. To date, theoretical models of these accretion flows are based on magnetohydrodynamics (MHD), a collisional fluid theory, sometimes (but rarely) extended with non-MHD features such as anisotropic (i.e. magnetic-field-aligned) viscosity and thermal conduction. While these extensions have been recognized as crucial, they require ad hoc assumptions about the role of microscopic kinetic instabilities (namely, firehose and mirror) in regulating the transport properties. These assumptions strongly affect the outcome of the calculations, and yet they have never been tested using more fundamental (i.e. kinetic) models. This proposal outlines a comprehensive first-principles study of the plasma physics of collisionless accretion flows using both analytic and state-of-the-art numerical models. The latter will utilize a new hybrid-kinetic particle-in-cell code, Pegasus, developed by the PI and Co-I specifically to study this problem. A comprehensive kinetic study of the 3D saturation of the magnetorotational instability in a collisionless plasma will be performed, in order to understand the interplay between turbulence, transport, and Larmor-scale kinetic instabilities such as firehose and mirror. Whether such instabilities alter the macroscopic saturated state, for example by limiting the transport of angular momentum by anisotropic pressure, will be addressed. Using these results, an appropriate "fluid" closure will be developed that can capture the multi-scale effects of plasma kinetics on magnetorotational turbulence, for use by the astrophysics community in building evolutionary models of accretion disks. The PI has already successfully performed the first three-dimensional kinetic

  7. Enhanced efficiency of organic solar cells by using ZnO as an electron-transport layer

    Science.gov (United States)

    Ullah, Irfan; Shah, Said Karim; Wali, Sartaj; Hayat, Khizar; Khattak, Shaukat Ali; Khan, Aurangzeb

    2017-12-01

    This paper reports the use of ZnO, processed by sol-gel, as an efficient electron-transport layer for inverted organic photovoltaic cells. The device with incorporated ZnO interlayer, annealed at 100 °C, between transparent electrode and blend film plays an effective role in enhancing photovoltaic properties: the short-circuit current density (J sc) doubles while open-circuit voltage (V oc) and fill factor increase by 0.12 V and 10 %, respectively. Power conversion efficiency (PCE) of solar cell increases, approximately, three times. The improvement in the PCE is attributed to the presence of ZnO which, being an electron-facilitating layer, provides an energy step for charge collection at electrodes.

  8. Transport phenomena and fouling in vacuum enhanced direct contact membrane distillation: Experimental and modelling

    KAUST Repository

    Naidu, Gayathri

    2016-08-27

    The application of vacuum to direct contact membrane distillation (vacuum enhanced direct contact membrane distillation, V-DCMD) removed condensable gasses and reduced partial pressure in the membrane pores, achieving 37.6% higher flux than DCMD at the same feed temperature. Transfer mechanism and temperature distribution profile in V-DCMD were studied. The empirical flux decline (EFD) model represented fouling profiles of V-DCMD. In a continuous V-DCMD operation with moderate temperature (55 degrees C) and permeate pressure (300 mbar) for treating wastewater ROC, a flux of 16.0 +/- 0.3 L/m(2) h and high quality distillate were achieved with water flushing, showing the suitability of V-DCMD for ROC treatment. (C) 2016 Elsevier B.V. All rights reserved.

  9. Transport phenomena and fouling in vacuum enhanced direct contact membrane distillation: Experimental and modelling

    KAUST Repository

    Naidu, Gayathri; Shim, Wang Geun; Jeong, Sanghyun; Choi, YoungKwon; Ghaffour, NorEddine; Vigneswaran, Saravanamuthu

    2016-01-01

    The application of vacuum to direct contact membrane distillation (vacuum enhanced direct contact membrane distillation, V-DCMD) removed condensable gasses and reduced partial pressure in the membrane pores, achieving 37.6% higher flux than DCMD at the same feed temperature. Transfer mechanism and temperature distribution profile in V-DCMD were studied. The empirical flux decline (EFD) model represented fouling profiles of V-DCMD. In a continuous V-DCMD operation with moderate temperature (55 degrees C) and permeate pressure (300 mbar) for treating wastewater ROC, a flux of 16.0 +/- 0.3 L/m(2) h and high quality distillate were achieved with water flushing, showing the suitability of V-DCMD for ROC treatment. (C) 2016 Elsevier B.V. All rights reserved.

  10. Local synaptic signaling enhances the stochastic transport of motor-driven cargo in neurons

    KAUST Repository

    Newby, Jay

    2010-08-23

    The tug-of-war model of motor-driven cargo transport is formulated as an intermittent trapping process. An immobile trap, representing the cellular machinery that sequesters a motor-driven cargo for eventual use, is located somewhere within a microtubule track. A particle representing a motor-driven cargo that moves randomly with a forward bias is introduced at the beginning of the track. The particle switches randomly between a fast moving phase and a slow moving phase. When in the slow moving phase, the particle can be captured by the trap. To account for the possibility that the particle avoids the trap, an absorbing boundary is placed at the end of the track. Two local signaling mechanisms-intended to improve the chances of capturing the target-are considered by allowing the trap to affect the tug-of-war parameters within a small region around itself. The first is based on a localized adenosine triphosphate (ATP) concentration gradient surrounding a synapse, and the second is based on a concentration of tau-a microtubule-associated protein involved in Alzheimer\\'s disease-coating the microtubule near the synapse. It is shown that both mechanisms can lead to dramatic improvements in the capture probability, with a minimal increase in the mean capture time. The analysis also shows that tau can cause a cargo to undergo random oscillations, which could explain some experimental observations. © 2010 IOP Publishing Ltd.

  11. Performance enhancement using power beaming for electric propulsion earth orbital transporters

    International Nuclear Information System (INIS)

    Dagle, J.E.

    1991-01-01

    An electric propulsion Earth orbital transport vehicle (EOTV) can effectively deliver large payloads using much less propellant than chemical transfer methods. By using an EOTV instead of a chemical upper stage, either a smaller launch vehicle can be used for the same satellite mass or a larger satellite can be deployed using the same launch vehicle. However, the propellant mass savings from using the higher specific impulse of electric propulsion may not be enough to overcome the disadvantage of the added mass and cost of the electric propulsion power source. Power system limitations have been a major factor delaying the acceptance and use of electric propulsion. This paper outlines the power requirements of electric propulsion technology being developed today, including arcjets, magnetoplasmadynamic (MPD) thrusters, and ion engines. Power supply characteristics are discussed for nuclear, solar, and power-beaming systems. Operational characteristics are given for each, as are the impacts of the power supply alternative on the overall craft performance. Because of its modular nature, the power-beaming approach is able to meet the power requirements of all three electric propulsion types. Also, commonality of approach allows different electric propulsion approaches to be powered by a single power supply approach. Power beaming exhibits better flexibility and performance than on-board nuclear or solar power systems

  12. Reverse Cholesterol Transport: Molecular Mechanisms and the Non-medical Approach to Enhance HDL Cholesterol

    Directory of Open Access Journals (Sweden)

    Leandro R. Marques

    2018-05-01

    Full Text Available Dyslipidemia (high concentrations of LDL-c and low concentrations of HDL-c is a major cause of cardiovascular events, which are the leading cause of death in the world. On the other hand, nutrition and regular exercise can be an interesting strategy to modulate lipid profile, acting as prevention or treatment, inhibiting the risk of diseases due to its anti-inflammatory and anti-atherogenic characteristics. Additionally, the possibility of controlling different training variables, such as type, intensity and recovery interval, can be used to maximize the benefits of exercise in promoting cardiovascular health. However, the mechanisms by which exercise and nutrients act in the regulation of cholesterol and its fractions, such as reverse cholesterol transport, receptors and transcription factors involved, such as PPARs and their role related to exercise, deserve further discussion. Therefore, the objective of this review is to debate about non-medical approaches to increase HDL-c, such as nutritional and training strategies, and to discuss the central mechanisms involved in the modulation of lipid profile during exercise, as well as that can be controlled by physical trainers or sports specialists in attempt to maximize the benefits promoted by exercise. The search for papers was performed in the databases: Medline (Pubmed, Science Direct, Scopus, Sport Discus, Web of Science, Scielo and Lilacs until February 2016.

  13. Enhanced interfacial thermal transport in pnictogen tellurides metallized with a lead-free solder alloy

    Energy Technology Data Exchange (ETDEWEB)

    Devender,; Ramanath, Ganpati, E-mail: Ramanath@rpi.edu [Department of Materials Science and Engineering, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States); Lofgreen, Kelly; Devasenathipathy, Shankar; Swan, Johanna; Mahajan, Ravi [Intel Corporation, Assembly Test and Technology Development, Chandler, Arizona 85226 (United States); Borca-Tasciuc, Theodorian [Department of Mechanical Aerospace and Nuclear Engineering, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States)

    2015-11-15

    Controlling thermal transport across metal–thermoelectric interfaces is essential for realizing high efficiency solid-state refrigeration and waste-heat harvesting power generation devices. Here, the authors report that pnictogen chalcogenides metallized with bilayers of Sn{sub 96.5}Ag{sub 3}Cu{sub 0.5} solder and Ni barrier exhibit tenfold higher interfacial thermal conductance Γ{sub c} than that obtained with In/Ni bilayer metallization. X-ray diffraction and x-ray spectroscopy indicate that reduced interdiffusion and diminution of interfacial SnTe formation due to Ni layer correlates with the higher Γ{sub c}. Finite element modeling of thermoelectric coolers metallized with Sn{sub 96.5}Ag{sub 3}Cu{sub 0.5}/Ni bilayers presages a temperature drop ΔT ∼ 22 K that is 40% higher than that obtained with In/Ni metallization. Our results underscore the importance of controlling chemical intermixing at solder–metal–thermoelectric interfaces to increase the effective figure of merit, and hence, the thermoelectric cooling efficiency. These findings should facilitate the design and development of lead-free metallization for pnictogen chalcogenide-based thermoelectrics.

  14. 7-ketocholesteryl-9-carboxynonanoate enhances ATP binding cassette transporter A1 expression mediated by PPARγ in THP-1 macrophages.

    Science.gov (United States)

    Chi, Yan; Wang, Le; Liu, Yuanyuan; Ma, Yanhua; Wang, Renjun; Han, Xiaofei; Qiao, Hui; Lin, Jiabin; Matsuura, Eiji; Liu, Shuqian; Liu, Qingping

    2014-06-01

    ATP binding cassette transporter A1 (ABCA1) is a member of the ATP-binding cassette transporter family. It plays an essential role in mediating the efflux of excess cholesterol. It is known that peroxisome proliferator-activated receptor gamma (PPARγ) promoted ABCA1 expression. We previously found 7-ketocholesteryl-9-carboxynonanoate (oxLig-1) upregulated ABCA1 partially through CD36 mediated signals. In the present study, we intended to test if PPARγ signally is involved in the upregulation mediated by oxLig-1. First, we docked oxLig-1 and the ligand-binding domain (LBD) of PPARγ by using AutoDock 3.05 and subsequently confirmed the binding by ELISA assay. Western blotting analyses showed that oxLig-1 induces liver X receptor alpha (LXRα), PPARγ and consequently ABCA1 expression. Furthermore, oxLig-1 significantly enhanced ApoA-I-mediated cholesterol efflux. Pretreatment with an inhibitor for PPARγ (GW9662) or/and LXRα (GGPP) attenuated oxLig-1-induced ABCA1 expression. Under PPARγ knockdown by using PPARγ-shRNA, oxLig-1-induced ABCA1 expression and cholesterol efflux in THP-1 macrophages was blocked by 62% and 25% respectively. These observations suggest that oxLig-1 is a novel PPARγ agonist, promoting ApoA-I-mediated cholesterol efflux from THP-1 macrophages by increasing ABCA1 expression via induction of PPARγ. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  15. BoALMT1, an Al-Induced Malate Transporter in Cabbage, Enhances Aluminum Tolerance in Arabidopsis thaliana

    Directory of Open Access Journals (Sweden)

    Lei Zhang

    2018-01-01

    Full Text Available Aluminum (Al is present in approximately 50% of the arable land worldwide and is regarded as the main limiting factor of crop yield on acidic soil. Al-induced root malate efflux plays an important role in the Al tolerance of plants. Here, the aluminum induced malate transporter BoALMT1 (KF322104 was cloned from cabbage (Brassica oleracea. BoALMT1 showed higher expression in roots than in shoots. The expression of BoALMT1 was specifically induced by Al treatment, but not the trivalent cations lanthanum (La, cadmium (Cd, zinc (Zn, or copper (Cu. Subcellular localization studies were performed in onion epidermal cells and revealed that BoALMT1 was localized at the plasma membrane. Scanning Ion-selective Electrode Technique was used to analyze H+ flux. Xenopus oocytes and Arabidopsis thaliana expressing BoALMT1 excreted more H+ under Al treatment. Overexpressing BoALMT1 in transgenic Arabidopsis resulted in enhanced Al tolerance and increased malate secretion. The results suggested that BoALMT1 functions as an Al-resistant gene and encodes a malate transporter. Expressing BoALMT1 in Xenopus oocytes or A. thaliana indicated that BoALMT1 could increase malate secretion and H+ efflux to resist Al tolerance.

  16. Evidence for a poloidally localized enhancement of radial transport in the scrape-off layer of the Tore Supra tokamak

    International Nuclear Information System (INIS)

    Gunn, J.P.; Boucher, C.; Dionne, M.; Duran, I.; Fuchs, V.; Loarer, T.; Nanobashvili, I.; Panek, R.; Pascal, J.-Y.; Saint-Laurent, F.; Stoeckel, J.; Rompuy, T. van; Zagorski, R.; Adamek, J.; Bucalossi, J.; Dejarnac, R.; Devynck, P.; Hertout, P.; Hron, M.; Lebrun, G.; Moreau, P.; Rimini, F.; Sarkissian, A.; Oost, G. van

    2007-01-01

    Near-sonic parallel flows are systematically observed in the far scrape-off layer (SOL) of the limiter tokamak Tore Supra, as in many L-mode X-point divertor tokamak plasmas. The poloidal variation of the parallel flow has been measured by moving the contact point of a small circular plasma onto limiters at different poloidal angles. The resulting variations of flow are consistent with the existence of a poloidally localized enhancement of radial transport concentrated in a 30 deg. sector near the outboard midplane. If the plasma contact point is placed on the inboard limiters, then the SOL expands to fill all the space between the plasma and the outboard limiters, with density decay lengths between 10 and 20 cm. On the other hand, if the contact point lies on the outboard limiters, the localized plasma outflux is scraped off and the SOL is very thin with decay lengths around 2-3 cm. The outboard radial transport would have to be about two orders of magnitude stronger than inboard to explain these results

  17. Enhancing Photovoltaic Performance of Inverted Planar Perovskite Solar Cells by Cobalt-Doped Nickel Oxide Hole Transport Layer.

    Science.gov (United States)

    Xie, Yulin; Lu, Kai; Duan, Jiashun; Jiang, Youyu; Hu, Lin; Liu, Tiefeng; Zhou, Yinhua; Hu, Bin

    2018-04-25

    Electron and hole transport layers have critical impacts on the overall performance of perovskite solar cells (PSCs). Herein, for the first time, a solution-processed cobalt (Co)-doped NiO X film was fabricated as the hole transport layer in inverted planar PSCs, and the solar cells exhibit 18.6% power conversion efficiency. It has been found that an appropriate Co-doping can significantly adjust the work function and enhance electrical conductivity of the NiO X film. Capacitance-voltage ( C- V) spectra and time-resolved photoluminescence spectra indicate clearly that the charge accumulation becomes more pronounced in the Co-doped NiO X -based photovoltaic devices; it, as a consequence, prevents the nonradiative recombination at the interface between the Co-doped NiO X and the photoactive perovskite layers. Moreover, field-dependent photoluminescence measurements indicate that Co-doped NiO X -based devices can also effectively inhibit the radiative recombination process in the perovskite layer and finally facilitate the generation of photocurrent. Our work indicates that Co-doped NiO X film is an excellent candidate for high-performance inverted planar PSCs.

  18. Enhanced Absorption and Growth Inhibition with Amino Acid Monoester Prodrugs of Floxuridine by Targeting hPEPT1 Transporters

    Directory of Open Access Journals (Sweden)

    Gordon L. Amidon

    2008-06-01

    Full Text Available A series of amino acid monoester prodrugs of floxuridine was synthesized and evaluated for the improvement of oral bioavailability and the feasibility of target drug delivery via oligopeptide transporters. All floxuridine 5′-amino acid monoester prodrugs exhibited PEPT1 affinity, with inhibition coefficients of Gly-Sar uptake (IC50 ranging from 0.7 – 2.3 mM in Caco-2 and 2.0 – 4.8 mM in AsPC-1 cells, while that of floxuridine was 7.3 mM and 6.3 mM, respectively. Caco-2 membrane permeabilities of floxuridine prodrugs (1.01 – 5.31 x 10-6 cm/sec and floxuridine (0.48 x 10-6 cm/sec were much higher than that of 5-FU (0.038 x 10-6 cm/sec. MDCK cells stably transfected with the human oligopeptide transporter PEPT1 (MDCK/hPEPT1 exhibited enhanced cell growth inhibition in the presence of the prodrugs. This prodrug strategy offers great potential, not only for increased drug absorption but also for improved tumor selectivity and drug efficacy.

  19. Enhanced absorption and growth inhibition with amino acid monoester prodrugs of floxuridine by targeting hPEPT1 transporters.

    Science.gov (United States)

    Tsume, Yasuhiro; Vig, Balvinder S; Sun, Jing; Landowski, Christopher P; Hilfinger, John M; Ramachandran, Chandrasekharan; Amidon, Gordon L

    2008-06-28

    A series of amino acid monoester prodrugs of floxuridine was synthesized and evaluated for the improvement of oral bioavailability and the feasibility of target drug delivery via oligopeptide transporters. All floxuridine 5'-amino acid monoester prodrugs exhibited PEPT1 affinity, with inhibition coefficients of Gly-Sar uptake (IC50) ranging from 0.7 - 2.3 mM in Caco-2 and 2.0 - 4.8 mM in AsPC-1 cells, while that of floxuridine was 7.3 mM and 6.3 mM, respectively. Caco-2 membrane permeabilities of floxuridine prodrugs (1.01 - 5.31 x 10(-6 )cm/sec) and floxuridine (0.48 x 10(-6 )cm/sec) were much higher than that of 5-FU (0.038 x 10(-6) cm/sec). MDCK cells stably transfected with the human oligopeptide transporter PEPT1 (MDCK/hPEPT1) exhibited enhanced cell growth inhibition in the presence of the prodrugs. This prodrug strategy offers great potential, not only for increased drug absorption but also for improved tumor selectivity and drug efficacy.

  20. Revisiting the Energy Budget of WASP-43b: Enhanced Day–Night Heat Transport

    Energy Technology Data Exchange (ETDEWEB)

    Keating, Dylan; Cowan, Nicolas B. [Department of Physics, McGill University, 3600 rue University, Montréal, QC H3A 2T8 (Canada)

    2017-11-01

    The large day–night temperature contrast of WASP-43b has so far eluded explanation. We revisit the energy budget of this planet by considering the impact of reflected light on dayside measurements and the physicality of implied nightside temperatures. Previous analyses of the infrared eclipses of WASP-43b have assumed reflected light from the planet is negligible and can be ignored. We develop a phenomenological eclipse model including reflected light, thermal emission, and water absorption, and we use it to fit published Hubble and Spitzer eclipse data. We infer a near-infrared geometric albedo of 24% ± 1% and a cooler dayside temperature of 1483 ± 10 K. Additionally, we perform light curve inversion on the three published orbital phase curves of WASP-43b and find that each suggests unphysical, negative flux on the nightside. By requiring non-negative brightnesses at all longitudes, we correct the unphysical parts of the maps and obtain a much hotter nightside effective temperature of 1076 ± 11 K. The cooler dayside and hotter nightside suggest a heat recirculation efficiency of 51% for WASP-43b, essentially the same as for HD 209458b, another hot Jupiter with nearly the same temperature. Our analysis therefore reaffirms the trend that planets with lower irradiation temperatures have more efficient day–night heat transport. Moreover, we note that (1) reflected light may be significant for many near-IR eclipse measurements of hot Jupiters, and (2) phase curves should be fit with physically possible longitudinal brightness profiles—it is insufficient to only require that the disk-integrated light curve be non-negative.

  1. Defect-Induced Photoluminescence Enhancement and Corresponding Transport Degradation in Individual Suspended Carbon Nanotubes

    Science.gov (United States)

    Wang, Bo; Shen, Lang; Yang, Sisi; Chen, Jihan; Echternach, Juliana; Dhall, Rohan; Kang, DaeJin; Cronin, Stephen

    2018-05-01

    This paper is a contribution to the Physical Review Applied collection in memory of Mildred S. Dresselhaus. The utilization of defects in carbon nanotubes to improve their photoluminescence efficiency has become a widespread study of the realization of efficient light-emitting devices. Here, we report a detailed comparison of the defects in nanotubes (quantified by Raman spectroscopy) and photoluminescence (PL) intensity of individual suspended carbon nanotubes (CNTs). We also evaluate the impact of these defects on the electron or hole transport in the nanotubes, which is crucial for the ultimate realization of optoelectronic devices. We find that brightly luminescent nanotubes exhibit a pronounced D-band in their Raman spectra, and vice versa, dimly luminescent nanotubes exhibit almost no D-band. Here, defects are advantageous for light emission by trapping excitons, which extend their lifetimes. We quantify this behavior by plotting the PL intensity as a function of the ID /IG -band Raman intensity ratio, which exhibits a Lorentzian distribution peaked at ID /IG=0.17 . For CNTs with a ID /IG ratio >0.25 , the PL intensity decreases, indicating that above some critical density, nonradiative recombination at defect sites dominates over the advantages of exciton trapping. In an attempt to fabricate optoelectronic devices based on these brightly luminescent CNTs, we transfer these suspended CNTs to platinum electrodes and find that the brightly photoluminescent nanotubes exhibit nearly infinite resistance due to these defects, while those without bright photoluminescence exhibit finite resistance. These findings indicate a potential limitation in the use of brightly luminescent CNTs for optoelectronic applications.

  2. Engineering of dendrimer surfaces to enhance transepithelial transport and reduce cytotoxicity.

    Science.gov (United States)

    Jevprasesphant, Rachaneekorn; Penny, Jeffrey; Attwood, David; McKeown, Neil B; D'Emanuele, Antony

    2003-10-01

    To evaluate the cytotoxicity, permeation, and transport mechanisms of PAMAM dendrimers and surface-modified cationic PAMAM dendrimers using monolayers of the human colon adenocarcinoma cell line, Caco-2. Cytotoxicity was determined using the MTT assay. The effect of dendrimers on monolayer integrity was determined from measurements of transepithelial electrical resistance (TEER) and [14C]mannitol apparent permeability coefficient (Papp). The Papp of dendrimers through monolayers was measured in both the apical (A)-to-basolateral (B) and B --> A directions at 4 degrees C and 37 degrees C and also in the presence and absence of ethylenediamine tetraacetic acid (EDTA) and colchicine. The cytotoxicity and permeation of dendrimers increased with both concentration and generation. The cytotoxicity of cationic dendrimers (G2, G3, G4) was greater than that of anionic dendrimers (G2.5, G3.5) but was reduced by conjugation with lauroyl chloride: the least cytotoxic conjugates were those with six attached lauroyl chains. At 37 degrees C the Papp of cationic dendrimers was higher than that of anionic dendrimers and, in general, increased with the number of attached lipid chains. Cationic dendrimers decreased TEER and significantly increased the Papp of mannitol. Modified dendrimers also reduced TEER and caused a more marked increase in the Papp of mannitol. The Papp values of dendrimers and modified dendrimers were higher in the presence of EDTA, lower in the presence of colchicine, and lower at 4 degrees C than at 37 degrees C. The properties of dendrimers may be significantly modified by surface engineering. Conjugation of cationic PAMAM dendrimers with lauroyl chloride decreased their cytotoxicity and increased their permeation through Caco-2 cell monolayers. Both PAMAM dendrimers and lauroyl-PAMAM dendrimer conjugates can cross epithelial monolayers by paracellular and transcellular pathways.

  3. Study of tunneling transport in Si-based tunnel field-effect transistors with ON current enhancement utilizing isoelectronic trap

    Science.gov (United States)

    Mori, Takahiro; Morita, Yukinori; Miyata, Noriyuki; Migita, Shinji; Fukuda, Koichi; Mizubayashi, Wataru; Masahara, Meishoku; Yasuda, Tetsuji; Ota, Hiroyuki

    2015-02-01

    The temperature dependence of the tunneling transport characteristics of Si diodes with an isoelectronic impurity has been investigated in order to clarify the mechanism of the ON-current enhancement in Si-based tunnel field-effect transistors (TFETs) utilizing an isoelectronic trap (IET). The Al-N complex impurity was utilized for IET formation. We observed three types of tunneling current components in the diodes: indirect band-to-band tunneling (BTBT), trap-assisted tunneling (TAT), and thermally inactive tunneling. The indirect BTBT and TAT current components can be distinguished with the plot described in this paper. The thermally inactive tunneling current probably originated from tunneling consisting of two paths: tunneling between the valence band and the IET trap and tunneling between the IET trap and the conduction band. The probability of thermally inactive tunneling with the Al-N IET state is higher than the others. Utilization of the thermally inactive tunneling current has a significant effect in enhancing the driving current of Si-based TFETs.

  4. Enhanced Electrochemical and Thermal Transport Properties of Graphene/MoS2 Heterostructures for Energy Storage: Insights from Multiscale Modeling.

    Science.gov (United States)

    Gong, Feng; Ding, Zhiwei; Fang, Yin; Tong, Chuan-Jia; Xia, Dawei; Lv, Yingying; Wang, Bin; Papavassiliou, Dimitrios V; Liao, Jiaxuan; Wu, Mengqiang

    2018-05-02

    Graphene has been combined with molybdenum disulfide (MoS 2 ) to ameliorate the poor cycling stability and rate performance of MoS 2 in lithium ion batteries, yet the underlying mechanisms remain less explored. Here, we develop multiscale modeling to investigate the enhanced electrochemical and thermal transport properties of graphene/MoS 2 heterostructures (GM-Hs) with a complex morphology. The calculated electronic structures demonstrate the greatly improved electrical conductivity of GM-Hs compared to MoS 2 . Increasing the graphene layers in GM-Hs not only improves the electrical conductivity but also stabilizes the intercalated Li atoms in GM-Hs. It is also found that GM-Hs with three graphene layers could achieve and maintain a high thermal conductivity of 85.5 W/(m·K) at a large temperature range (100-500 K), nearly 6 times that of pure MoS 2 [∼15 W/(m·K)], which may accelerate the heat conduction from electrodes to the ambient. Our quantitative findings may shed light on the enhanced battery performances of various graphene/transition-metal chalcogenide composites in energy storage devices.

  5. Decouple electronic and phononic transport in nanotwinned structures: a new strategy for enhancing the figure-of-merit of thermoelectrics.

    Science.gov (United States)

    Zhou, Yanguang; Gong, Xiaojing; Xu, Ben; Hu, Ming

    2017-07-20

    Thermoelectric (TE) materials manifest themselves to enable direct conversion of temperature differences to electric power and vice versa. Though remarkable advances have been achieved in the past decades for various TE systems, the energy conversion efficiency of TE devices, which is characterized by a dimensionless figure-of-merit (ZT = S 2 σT/(κ el + κ ph )), generally remains a poor factor that severely limits TE devices' competitiveness and range of employment. The bottleneck for substantially boosting the ZT coefficient lies in the strong interdependence of the physical parameters involved in electronic (S and σ, and κ el ) and phononic (κ ph ) transport. Herein, we propose a new strategy of incorporating nanotwinned structures to decouple electronic and phononic transport. Combining the new concept of nanotwinned structures with the previously widely used nanocrystalline approach, the power factor of the nanotwin-nanocrystalline Si heterostructures is enhanced by 120% compared to that of bulk crystalline Si, while the lattice thermal conductivity is reduced to a level well below the amorphous limit, yielding a theoretical limit of 0.52 and 0.9 for ZT coefficient at room temperature and 1100 K, respectively. This value is almost two orders of magnitude larger than that for bulk Si and twice that for polycrystalline Si. Even for the experimentally obtained nanotwin-nanocrystalline heterostructures (e.g. grain size of 5 nm), the ZT coefficient can be as high as 0.26 at room temperature and 0.7 at 1100 K, which is the highest ZT value among all Si-based bulk nanostructures found thus far. Such substantial improvement stems from two aspects: (1) the improvement in the power factor is caused due to an increase in the Seebeck coefficient (degeneracy of the band valley) and the enhancement of electrical conductivity (the reduction of the effective band mass) and (2) the significant reduction of the lattice thermal conductivity is mainly caused due to the

  6. Prior fear conditioning does not impede enhanced active avoidance in serotonin transporter knockout rats.

    Science.gov (United States)

    Schipper, Pieter; Henckens, Marloes J A G; Borghans, Bart; Hiemstra, Marlies; Kozicz, Tamas; Homberg, Judith R

    2017-05-30

    Stressors can be actively or passively coped with, and adequate adaption of the coping response to environmental conditions can reduce their potential deleterious effects. One major factor influencing stress coping behaviour is serotonin transporter (5-HTT) availability. Abolishment of 5-HTT is known to impair fear extinction but facilitates acquisition of signalled active avoidance (AA), a behavioural task in which an animal learns to avoid an aversive stimulus that is predicted by a cue. Flexibility in adapting coping behaviour to the nature of the stressor shapes resilience to stress-related disorders. Therefore, we investigated the relation between 5-HTT expression and ability to adapt a learned coping response to changing environmental conditions. To this end, we first established and consolidated a cue-conditioned passive fear response in 5-HTT -/- and wildtype rats. Next, we used the conditioned stimulus (CS) to signal oncoming shocks during signalled AA training in 5-HTT -/- and wildtype rats to study their capability to acquire an active coping response to the CS following fear conditioning. Finally, we investigated the behavioural response to the CS in a novel environment and measured freezing, exploration and self-grooming, behaviours reflective of stress coping strategy. We found that fear conditioned and sham conditioned 5-HTT -/- animals acquired the signalled AA response faster than wildtypes, while prior conditioning briefly delayed AA learning similarly in both genotypes. Subsequent exposure to the CS in the novel context reduced freezing and increased locomotion in 5-HTT -/- compared to wildtype rats. This indicates that improved AA performance in 5-HTT -/- rats resulted in a weaker residual passive fear response to the CS in a novel context. Fear conditioning prior to AA training did not affect freezing upon re-encountering the CS, although it did reduce locomotion in 5-HTT -/- rats. We conclude that independent of 5-HTT signalling, prior fear

  7. DEVELOPMENT OF MICROORGANISMS WITH IMPROVED TRANSPORT AND BIOSURFACTANT ACTIVITY FOR ENHANCED OIL RECOVERY

    Energy Technology Data Exchange (ETDEWEB)

    M.J. McInerney; R.M. Knapp; D.P. Nagle, Jr.; Kathleen Duncan; N. Youssef; M.J. Folmsbee; S. Maudgakya

    2003-06-26

    Biosurfactants enhance hydrocarbon biodegradation by increasing apparent aqueous solubility or affecting the association of the cell with poorly soluble hydrocarbon. Here, we show that a lipopeptide biosurfactant produced by Bacillus mojavensis strain JF-2 mobilized substantial amounts of residual hydrocarbon from sand-packed columns when a viscosifying agent and a low molecular weight alcohol were present. The amount of residual hydrocarbon mobilized depended on the biosurfactant concentration. One pore volume of cell-free culture fluid with 900 mg/l of the biosurfactant, 10 mM 2,3-butanediol and 1000 mg/l of partially hydrolyzed polyacrylamide polymer mobilized 82% of the residual hydrocarbon. Consistent with the high residual oil recoveries, we found that the bio-surfactant lowered the interfacial tension (IFT) between oil and water by nearly 2 orders of magnitude compared to typical IFT values of 28-29 mN/m. Increasing the salinity increased the IFT with or without 2,3-butanediol present. The lowest interfacial tension observed was 0.1 mN/m. The lipopeptide biosurfactant system may be effective in removing hydrocarbon contamination sources in soils and aquifers and for the recovery of entrapped oil from low production oil reservoirs. Previously, we reported that Proteose peptone was necessary for anaerobic growth and biosurfactant production by B. mojavensis JF-2. The data gathered from crude purification of the growth-enhancing factor in Proteose peptone suggested that it consisted of nucleic acids; however, nucleic acid bases, nucleotides or nucleosides did not replace the requirement for Proteose Peptone. Further studies revealed that salmon sperm DNA, herring sperm DNA, Echerichia coli DNA and synthetic DNA replaced the requirement for Proteose peptone. In addition to DNA, amino acids and nitrate were required for anaerobic growth and vitamins further improved growth. We now have a defined medium that can be used to manipulate growth and biosurfactant

  8. Enhancement of intestinal water absorption and sodium transport by glycerol in rats.

    Science.gov (United States)

    Wapnir, R A; Sia, M C; Fisher, S E

    1996-12-01

    Glycerol (Gly) is a hydrophilic, absorbable, and energy-rich solute that could make water absorption more efficient. We investigated the use of Gly in a high-energy beverage containing corn syrup (CS) by using a small intestine perfusion procedure in the rat, an approach shown earlier to provide good preclinical information. The effectiveness of several formulations with Gly and CS was compared with commercial products and to experimental formulas where Gly substituted for glucose (Glc). The CS-Gly combination was more effective than preparations on the market containing sucrose and Glc-fructose syrups (G-P and G-L, respectively) in maintaining a net water absorption balance in the test jejunal segment [CS-Gly = 0.21 +/- 0.226, G-L = -1.516 +/- 0.467, and G-P = -0.299 +/- 0.106 (SE) microliter.min-1.cm-1 (P = 0.0113)] and in reducing sodium release into the lumen [CS-Gly = -133.2 +/- 16.2, G-L = -226.7 +/- 25.2, and G-P = -245.6 +/- 23.4 nmol.min-1.cm-1 (P = 0.0022)]. In other preparations, at equal CS concentrations (60 and 80 g/l, respectively), Gly clearly improved net water absorption over a comparable Glc-containing product [CS60-Gly = 0.422 +/- 0.136 and CS80-Gly = 0.666 +/- 0.378 vs. CS60-Glc = -0.282 +/- 0.200 and CS80-Glc = -1.046 +/- 0.480 microliters.min-1.cm-1 (P = 0.0019)]. On the basis of the data of this rat intestine perfusion model, Gly could be a useful ingredient in energy-rich beverages and might enhance fluid absorption in humans.

  9. Coherent and correlated spin transport in nanoscale superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Morten, Jan Petter

    2008-03-15

    Motivated by the desire for better understanding of nano electronic systems, we theoretically study the conductance and noise characteristics of current flow between superconductors, ferromagnets, and normal-metals. Such nano structures can reveal information about superconductor proximity effects, spin-relaxation processes, and spintronic effects with potential applications for different areas of mesoscopic physics. We employ the quasiclassical theory of superconductivity in the Keldysh formalism, and calculate the nonequilibrium transport of spin and charge using various approaches like the circuit theory of quantum transport and full counting statistics. For two of the studied structures, we have been able to compare our theory to experimental data and obtain good agreement. Transport and relaxation of spin polarized current in superconductors is governed by energy-dependent transport coefficients and spin-flip rates which are determined by quantum interference effects. We calculate the resulting temperature-dependent spin flow in ferromagnet-superconductor devices. Experimental data for spin accumulation and spin relaxation in a superconducting nano wire is in agreement with the theory, and allows for a spin-flip spectroscopy that determines the dominant mechanism for spin-flip relaxation in the studied samples. A ferromagnet precessing under resonance conditions can give rise to pure spin current injection into superconductors. We find that the absorbed spin current is measurable as a temperature dependent Gilbert damping, which we calculate and compare to experimental data. Crossed Andreev reflection denotes superconducting pairing of electrons flowing from different normal-metal or ferromagnet terminals into a superconductor. We calculate the nonlocal currents resulting from this process in competition with direct electron transport between the normal-metal terminals. We take dephasing into account, and study the nonlocal current when the types of contact in

  10. Geometric dependence of Nb-Bi2Te3-Nb topological Josephson junction transport parameters

    International Nuclear Information System (INIS)

    Molenaar, C G; Leusink, D P; Brinkman, A; Wang, X L

    2014-01-01

    Superconductor-topological insulator–superconductor Josephson junctions have been fabricated in order to study the width dependence of the critical current, normal state resistance and flux periodicity of the critical current modulation in an external field. Previous literature reports suggest anomalous scaling in topological junctions due to the presence of Majorana bound states. However, for most realized devices, one would expect that trivial 2π-periodic Andreev levels dominate transport. We also observe anomalous scaling behaviour of junction parameters, but the scaling can be well explained by mere geometric effects, such as the parallel bulk conductivity shunt and flux focusing. (paper)

  11. Butyrate activates the monocarboxylate transporter MCT4 expression in breast cancer cells and enhances the antitumor activity of 3-bromopyruvate.

    Science.gov (United States)

    Queirós, Odília; Preto, Ana; Pacheco, António; Pinheiro, Céline; Azevedo-Silva, João; Moreira, Roxana; Pedro, Madalena; Ko, Young H; Pedersen, Peter L; Baltazar, Fátima; Casal, Margarida

    2012-02-01

    Most malignant tumors exhibit the Warburg effect, which consists in increased glycolysis rates with production of lactate, even in the presence of oxygen. Monocarboxylate transporters (MCTs), maintain these glycolytic rates, by mediating the influx and/or efflux of lactate and are overexpressed in several cancer cell types. The lactate and pyruvate analogue 3-bromopyruvate (3-BP) is an inhibitor of the energy metabolism, which has been proposed as a specific antitumor agent. In the present study, we aimed at determining the effect of 3-BP in breast cancer cells and evaluated the putative role of MCTs on this effect. Our results showed that the three breast cancer cell lines used presented different sensitivities to 3-BP: ZR-75-1 ER (+)>MCF-7 ER (+)>SK-BR-3 ER (-). We also demonstrated that 3-BP reduced lactate production, induced cell morphological alterations and increased apoptosis. The effect of 3-BP appears to be cytotoxic rather than cytostatic, as a continued decrease in cell viability was observed after removal of 3-BP. We showed that pre-incubation with butyrate enhanced significantly 3-BP cytotoxicity, especially in the most resistant breast cancer cell line, SK-BR-3. We observed that butyrate treatment induced localization of MCT1 in the plasma membrane as well as overexpression of MCT4 and its chaperone CD147. Our results thus indicate that butyrate pre-treatment potentiates the effect of 3-BP, most probably by increasing the rates of 3-BP transport through MCT1/4. This study supports the potential use of butyrate as adjuvant of 3-BP in the treatment of breast cancer resistant cells, namely ER (-).

  12. Carbon Dioxide Transport and Sorption Behavior in Confined Coal Cores for Enhanced Coalbed Methane and CO2 Sequestration

    Energy Technology Data Exchange (ETDEWEB)

    Jikich, S.A.; McLendon, T.R.; Seshadri, K.S.; Irdi, G.A.; Smith, D.H.

    2007-11-01

    Measurements of sorption isotherms and transport properties of CO2 in coal cores are important for designing enhanced coalbed methane/CO2 sequestration field projects. Sorption isotherms measured in the lab can provide the upper limit on the amount of CO2 that might be sorbed in these projects. Because sequestration sites will most likely be in unmineable coals, many of the coals will be deep and under considerable lithostatic and hydrostatic pressures. These lithostatic pressures may significantly reduce the sorption capacities and/or transport rates. Consequently, we have studied apparent sorption and diffusion in a coal core under confining pressure. A core from the important bituminous coal Pittsburgh #8 was kept under a constant, three-dimensional external stress; the sample was scanned by X-ray computer tomography (CT) before, then while it sorbed, CO2. Increases in sample density due to sorption were calculated from the CT images. Moreover, density distributions for small volume elements inside the core were calculated and analyzed. Qualitatively, the computerized tomography showed that gas sorption advanced at different rates in different regions of the core, and that diffusion and sorption progressed slowly. The amounts of CO2 sorbed were plotted vs. position (at fixed times) and vs. time (for various locations in the sample). The resulting sorption isotherms were compared to isotherms obtained from powdered coal from the same Pittsburgh #8 extended sample. The results showed that for this single coal at specified times, the apparent sorption isotherms were dependent on position of the volume element in the core and the distance from the CO2 source. Also, the calculated isotherms showed that less CO2 was sorbed than by a powdered (and unconfined) sample of the coal. Changes in density distributions during the experiment were also observed. After desorption, the density distribution of calculated volume elements differed from the initial distribution

  13. Adenoviral-mediated placental gene transfer of IGF-1 corrects placental insufficiency via enhanced placental glucose transport mechanisms.

    Directory of Open Access Journals (Sweden)

    Helen N Jones

    Full Text Available Previous work in our laboratory demonstrated that over-expression of human insulin-like growth factor -1 (hIGF-1 in the placenta corrects fetal weight deficits in mouse, rat, and rabbit models of intrauterine growth restriction without changes in placental weight. The underlying mechanisms of this effect have not been elucidated. To investigate the effect of intra-placental IGF-1 over-expression on placental function we examined glucose transporter expression and localization in both a mouse model of IUGR and a model of human trophoblast, the BeWo Choriocarcinoma cell line.At gestational day 18, animals were divided into four groups; sham-operated controls, uterine artery branch ligation (UABL, UABL+Ad-hIGF-1 (10(8 PFU, UABL+Ad-LacZ (10(8 PFU. At gestational day 20, pups and placentas were harvested by C-section. For human studies, BeWo choriocarcinoma cells were grown in F12 complete medium +10%FBS. Cells were incubated in serum-free control media ± Ad-IGF-1 or Ad-LacZ for 48 hours. MOIs of 10∶1 and 100∶1 were utilized. The RNA, protein expression and localization of glucose transporters GLUT1, 3, 8, and 9 were analyzed by RT-PCR, Western blot and immunohistochemistry.In both the mouse placenta and BeWo, GLUT1 regulation was linked to altered protein localization. GLUT3, localized to the mouse fetal endothelial cells, was reduced in placental insufficiency but maintained with Ad-I GF-1 treatment. Interestingly, GLUT8 expression was reduced in the UABL placenta but up-regulated following Ad-IGF-1 in both mouse and human systems. GLUT9 expression in the mouse was increased by Ad-IGF-1 but this was not reflected in the BeWo, where Ad-IGF-1 caused moderate membrane relocalization.Enhanced GLUT isoform transporter expression and relocalization to the membrane may be an important mechanism in Ad-hIGF-1mediated correction of placental insufficiency.

  14. Methotrexate loaded polyether-copolyester dendrimers for the treatment of gliomas: enhanced efficacy and intratumoral transport capability.

    Science.gov (United States)

    Dhanikula, Renu Singh; Argaw, Anteneh; Bouchard, Jean-Francois; Hildgen, Patrice

    2008-01-01

    Therapeutic benefit in glial tumors is often limited due to low permeability of delivery systems across the blood-brain barrier (BBB), drug resistance, and poor penetration into the tumor tissue. In an attempt to overcome these hurdles, polyether-copolyester (PEPE) dendrimers were evaluated as drug carriers for the treatment of gliomas. Dendrimers were conjugated to d-glucosamine as the ligand for enhancing BBB permeability and tumor targeting. The efficacy of methotrexate (MTX)-loaded dendrimers was established against U87 MG and U 343 MGa cells. Permeability of rhodamine-labeled dendrimers and MTX-loaded dendrimers across the in vitro BBB model and their distribution into avascular human glioma tumor spheroids was also studied. Glucosylated dendrimers were found to be endocytosed in significantly higher amounts than nonglucosylated dendrimers by both the cell lines. IC 50 of MTX after loading in dendrimers was lower than that of the free MTX, suggesting that loading MTX in PEPE dendrimers increased its potency. Similar higher activity of MTX-loaded glucosylated and nonglucosylated dendrimers was found in the reduction of tumor spheroid size. These MTX-loaded dendrimers were able to kill even MTX-resistant cells highlighting their ability to overcome MTX resistance. In addition, the amount of MTX-transported across BBB was three to five times more after loading in the dendrimers. Glucosylation further increased the cumulative permeation of dendrimers across BBB and hence increased the amount of MTX available across it. Glucosylated dendrimers distributed through out the avascular tumor spheroids within 6 h, while nonglucosylated dendrimers could do so in 12 h. The results show that glucosamine can be used as an effective ligand not only for targeting glial tumors but also for enhanced permeability across BBB. Thus, glucosylated PEPE dendrimers can serve as potential delivery system for the treatment of gliomas.

  15. Enhanced long-distance transport of periodic electron beams in an advanced double layer cone-channel target

    Science.gov (United States)

    Ji, Yanling; Duan, Tao; Zhou, Weimin; Li, Boyuan; Wu, Fengjuan; Zhang, Zhimeng; Ye, Bin; Wang, Rong; Wu, Chunrong; Tang, Yongjian

    2018-02-01

    An enhanced long-distance transport of periodic electron beams in an advanced double layer cone-channel target is investigated using two-dimensional particle-in-cell simulations. The target consists of a cone attached to a double-layer hollow channel with a near-critical-density inner layer. The periodic electron beams are generated by the combination of ponderomotive force and longitudinal laser electric field. Then a stable electron propagation is achieved in the double-layer channel over a much longer distance without evident divergency, compared with a normal cone-channel target. Detailed simulations show that the much better long-distance collimation and guidance of energetic electrons is attributed to the much stronger electromagnetic fields at the inner wall surfaces. Furthermore, a continuous electron acceleration is obtained by the more intense laser electric fields and extended electron acceleration length in the channel. Our investigation shows that by employing this advanced target, both the forward-going electron energy flux in the channel and the energy coupling efficiency from laser to electrons are about threefold increased in comparison with the normal case.

  16. Enhanced long-distance transport of periodic electron beams in an advanced double layer cone-channel target

    Directory of Open Access Journals (Sweden)

    Yanling Ji

    2018-02-01

    Full Text Available An enhanced long-distance transport of periodic electron beams in an advanced double layer cone-channel target is investigated using two-dimensional particle-in-cell simulations. The target consists of a cone attached to a double-layer hollow channel with a near-critical-density inner layer. The periodic electron beams are generated by the combination of ponderomotive force and longitudinal laser electric field. Then a stable electron propagation is achieved in the double-layer channel over a much longer distance without evident divergency, compared with a normal cone-channel target. Detailed simulations show that the much better long-distance collimation and guidance of energetic electrons is attributed to the much stronger electromagnetic fields at the inner wall surfaces. Furthermore, a continuous electron acceleration is obtained by the more intense laser electric fields and extended electron acceleration length in the channel. Our investigation shows that by employing this advanced target, both the forward-going electron energy flux in the channel and the energy coupling efficiency from laser to electrons are about threefold increased in comparison with the normal case.

  17. Enhanced

    Directory of Open Access Journals (Sweden)

    Martin I. Bayala

    2014-06-01

    Full Text Available Land Surface Temperature (LST is a key parameter in the energy balance model. However, the spatial resolution of the retrieved LST from sensors with high temporal resolution is not accurate enough to be used in local-scale studies. To explore the LST–Normalised Difference Vegetation Index relationship potential and obtain thermal images with high spatial resolution, six enhanced image sharpening techniques were assessed: the disaggregation procedure for radiometric surface temperatures (TsHARP, the Dry Edge Quadratic Function, the Difference of Edges (Ts∗DL and three models supported by the relationship of surface temperature and water stress of vegetation (Normalised Difference Water Index, Normalised Difference Infrared Index and Soil wetness index. Energy Balance Station data and in situ measurements were used to validate the enhanced LST images over a mixed agricultural landscape in the sub-humid Pampean Region of Argentina (PRA, during 2006–2010. Landsat Thematic Mapper (TM and Moderate Resolution Imaging Spectroradiometer (EOS-MODIS thermal datasets were assessed for different spatial resolutions (e.g., 960, 720 and 240 m and the performances were compared with global and local TsHARP procedures. Results suggest that the Ts∗DL technique is the most adequate for simulating LST to high spatial resolution over the heterogeneous landscape of a sub-humid region, showing an average root mean square error of less than 1 K.

  18. Direct observation of hopping induced spin polarization current in oxygen deficient Co-doped ZnO by Andreev reflection technique

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Kung-Shang; Huang, Tzu-Yu; Dwivedi, G.D. [Department of Physics, National Sun Yat-sen University, Kaohsiung, Taiwan (China); Lin, Lu-Kuei; Lee, Shang-Fan [Taiwan Institute of Physics, Academia Sinica, Taipei, Taiwan (China); Sun, Shih-Jye [Department of Applied Physics, National Kaohsiung University, Kaohsiung, Taiwan (China); Chou, Hsiung, E-mail: hchou@mail.nsysu.edu.tw [Department of Physics, National Sun Yat-sen University, Kaohsiung, Taiwan (China)

    2017-07-01

    Highlights: • Co-doped ZnO thin-films were grown with varying V{sub O} concentartion. • PCAR measurements were done to study the SPC. • High spin polarization was observed above a certain V{sub O} concentartion. • High V{sub O} samples provide a high density of completed percolation path. • This complete percolation path gives rise to high SPC. - Abstract: Oxygen vacancy induced ferromagnetic coupling in diluted magnetic oxide (DMO) semiconductors have been reported in several studies, but technologically more crucial spin-polarized current (SPC) is still under-developed in DMOs. Few studies have claimed that VRH mechanism can originate the SPC, but, how VRH mechanism associated with percolation path, is not clearly understood. We used Point-contact Andreev reflection (PCAR) technique to probe the SPC in Co-doped ZnO (CZO) films. Since the high resistance samples cause broadening in conductance(G)-voltage(V) curves, which may result in an unreliable evaluation of spin polarization, we include two extra parameters, (i) effective temperature and (ii) spreading resistance, for the simulation to avoid the uncertainty in extracting spin polarization. The effective G-V curves and higher spin polarization can be obtained above a certain oxygen vacancy concentration. The number of completed and fragmentary percolation paths is proportional to the concentration of oxygen vacancies. For low oxygen vacancy samples, the Pb-tip has a higher probability of covering fragmentary percolation paths than the complete ones, due to its small contact size. The completed paths may remain independent of one another and get polarized in different directions, resulting in lower spin-polarization value. High oxygen vacancy samples provide a high density of completed path, most of them link to one another by crossing over, and gives rise to high spin-polarization value.

  19. Sustained enhancement of OCTN1 transporter expression in association with hydroxyurea induced gamma-globin expression in erythroid progenitors

    OpenAIRE

    Walker, Aisha L.; Ofori-Acquah, Solomon

    2016-01-01

    The clinical benefits of hydroxyurea treatment in patients with sickle cell disease (SCD) are due largely to increased gamma-globin expression. However, mechanisms that control gamma-globin expression by hydroxyurea in erythroid progenitors are incompletely understood. Here, we investigated the role of two hydroxyurea transporters, urea transporter B (UTB) and organic cation/carnitine transporter 1 (OCTN1), in this process. Endogenous expression of both transporters peaked towards the end of ...

  20. Maritime transport safety enhancement

    Energy Technology Data Exchange (ETDEWEB)

    Samuelides, Manolis [National Technical University of Athens (Greece); University School of Naval Architecture and Marine Engineering, Zografos (Greece). Div. for Marine Structures

    2013-11-15

    As the density of sea traffic keeps growing, designing ship structures capable of withstanding accidental loads such as collisions or grounding without detrimental consequences proves an ever-greater challenge. Double hull designs play a major role in this respect, as explains Manolis Samuelides, Professor at the National Technical University of Athens. (orig.)

  1. Maritime transport safety enhancement

    International Nuclear Information System (INIS)

    Samuelides, Manolis; University School of Naval Architecture and Marine Engineering, Zografos

    2013-01-01

    As the density of sea traffic keeps growing, designing ship structures capable of withstanding accidental loads such as collisions or grounding without detrimental consequences proves an ever-greater challenge. Double hull designs play a major role in this respect, as explains Manolis Samuelides, Professor at the National Technical University of Athens. (orig.)

  2. Spin polarization of a Ferromagnetic Narrow Gap p-(In,Mn)As Obtained from Andreev Reflection Spectroscopy

    International Nuclear Information System (INIS)

    Akazaki, T.; Munekata, H.; Yokoyama, T.; Tanaka, Y.; Takayanagi, H.

    2011-01-01

    Spin-polarized carrier transport across Nb/p-(In,Mn)As junctions has been studied. Suppressions of conductance in the superconductor sub-gap region and conductance peaks at the bias voltage around the edge of the sub-gap are observed. These features are well reproduced by a newly modified BTK model including both spin polarization and the inverse proximity effect. The value of spin polarization in p-(In,Mn)As extracted by the calculation is P = 0.725 at 0.5 K with Z = 0.25

  3. Non-equilibrium spin and charge transport in superconducting heterojunctions

    Energy Technology Data Exchange (ETDEWEB)

    Thalmann, Marcel; Rudolf, Marcel; Braun, Julian; Pietsch, Torsten; Scheer, Elke [Department of Physics, University of Konstanz, Universitaetsstrasse 10, 78464 Konstanz (Germany)

    2015-07-01

    Ferromagnet Superconductance (F/S) junctions are rich in exciting quantum-physical-phenomena, which are still poorly understood but may provide bright prospects for new applications. In contrast to conventional normal-metal proximity systems, Andreev reflection is suppressed for singlet cooper pairs in F/S heterostructures. However, long-range triplet pairing may be observed in S/F systems with non-collinear magnetization or spin-active interfaces. Herein, we investigate non-equilibrium transport properties of lateral S/F heterojunctions, defined via electron beam lithography. In particular we focus microwave- and magneto-transport spectroscopy on conventional type-I (Al, Pb, Zn) and type-II (Nb) superconductors in combination with strong transition metal ferromagnets (Ni, Co, Fe). A cryogenic HF readout platform and advanced electronic filtering is developed and results on Al-based heterojunctions are shown.

  4. l-Arginine Uptake by Cationic Amino Acid Transporter Promotes Intra-Macrophage Survival of Leishmania donovani by Enhancing Arginase-Mediated Polyamine Synthesis

    Directory of Open Access Journals (Sweden)

    Abhishek Mandal

    2017-07-01

    Full Text Available The survival of intracellular protozoan parasite, Leishmania donovani, the causative agent of Indian visceral leishmaniasis (VL, depends on the activation status of macrophages. l-Arginine, a semi-essential amino acid plays a crucial regulatory role for activation of macrophages. However, the role of l-arginine transport in VL still remains elusive. In this study, we demonstrated that intra-macrophage survival of L. donovani depends on the availability of extracellular l-arginine. Infection of THP-1-derived macrophage/human monocyte-derived macrophage (hMDM with Leishmania, resulted in upregulation of l-arginine transport. While investigating the involvement of the transporters, we observed that Leishmania survival was greatly impaired when the transporters were blocked either using inhibitor or siRNA-mediated downregulation. CAT-2 was found to be the main isoform associated with l-arginine transport in L. donovani-infected macrophages. l-arginine availability and its transport regulated the host arginase in Leishmania infection. Arginase and inducible nitric oxide synthase (iNOS expression were reciprocally regulated when assayed using specific inhibitors and siRNA-mediated downregulation. Interestingly, induction of iNOS expression and nitric oxide production were observed in case of inhibition of arginase in infected macrophages. Furthermore, inhibition of l-arginine transport as well as arginase resulted in decreased polyamine production, limiting parasite survival inside macrophages. l-arginine availability and transport regulated Th1/Th2 cytokine levels in case of Leishmania infection. Upregulation of l-arginine transport, induction of host arginase, and enhanced polyamine production were correlated with increased level of IL-10 and decreased level of IL-12 and TNF-α in L. donovani-infected macrophages. Our findings provide clear evidence for targeting the metabolism of l-arginine and l-arginine-metabolizing enzymes as an important

  5. Investigation of diffusional transport of heat and its enhancement in phase-change thermal energy storage systems

    International Nuclear Information System (INIS)

    Saraswat, Amit; Bhattacharjee, Rajdeep; Verma, Ankit; Das, Malay K.; Khandekar, Sameer

    2017-01-01

    Thermal energy storage in general, and phase-change materials (PCMs) in particular, have been a major topic of research for the last thirty years. Due to their favorable thermo-dynamical characteristics, such as high density, specific heat and latent heat of fusion, PCMs are usually employed as working fluids for thermal storage. However, low thermal conductivities of organic PCMs have posed a continuous challenge in its large scale deployment. This study focuses on experimental and numerical investigation of the melting process of industrial grade paraffin wax inside a semi-cylindrical enclosure with a heating strip attached axially along the center of semi-cylinder. During the first part of the study, the solid-liquid interface location, the liquid flow patterns in the melt pool, and the spatial and temporal variation of PCM temperature were recorded. For numerical simulation of the system, open source library OpenFOAM® was used in order to solve the coupled Navier-Stokes and energy equations in the considered system. It is seen that the enthalpy-porosity technique implemented on OpenFOAM® is reasonably well suited for handling melting/solidification problems and can be employed for system level design. Next, to overcome the inherent thermal limitations of PCM storage material, the study further explored the potential of coupling the existing heat source with copper-water heat pipes, so as to help augment the rate of heat dissipation within the medium by increasing the effective system-level thermal conductivity. Integration of heat pipes led to enhanced transport, and hence, a substantial decrease in the total required melting time. The study provides a framework for designing of large systems with integration of heat pipes with PCM based thermal storage systems.

  6. Performance assessment of gate material engineered AlInN/GaN underlap DG MOSFET for enhanced carrier transport efficiency

    Science.gov (United States)

    Pardeshi, Hemant M.; Raj, Godwin; Pati, Sudhansu; Mohankumar, N.; Sarkar, Chandan Kumar

    2013-08-01

    In the work proposed, performance of dual material gate (DMG) AlInN/GaN underlap DG MOSFET has been analyzed and compared with the corresponding performance of single material gate (SMG) AlInN/GaN underlap DG MOSFET using Sentaurus TCAD device simulation. A systematic, quantitative investigation of key device metrics for DMG-DG device is presented and a comparison with SMG-DG device is done for a wide range of gate and underlap lengths. The key idea in this paper is to demonstrate the improved performance exhibited by DMG-DG device over SMG-DG device, due to enhanced carrier transport efficiency and suppressed short channel effect (SCE). Simulation reveals an improvement in drain current, drain induced barrier lowering (DIBL), Ion/Ioff, Delay and Energy Delay Product (EDP) for DMG-DG MOSFET as compared to SMG-DG MOSFET. Very high drain current of 6.7 mA/μm, low DIBL of 1.62 mV/V, high Ion/Ioff ratio of 4.044e107, low delay of 0.001 ps and low EDP of 1.37e-31 J s/μm are obtained for DGM-DG device. However, subthreshold slope (SS) for DMG-DG device is on higher side than SMG-DG. The proposed AlInN/GaN Heterostructure Underlap DGM-DG MOSFET shows excellent promise as one of the candidates to substitute present MOSFET for future high speed applications.

  7. Brain-derived neurotrophic factor (BDNF) enhances GABA transport by modulating the trafficking of GABA transporter-1 (GAT-1) from the plasma membrane of rat cortical astrocytes

    DEFF Research Database (Denmark)

    Vaz, Sandra H; Jørgensen, Trine Nygaard; Cristóvão-Ferreira, Sofia

    2011-01-01

    /MAPK pathway and requires active adenosine A(2A) receptors. Transport through GAT-3 is not affected by BDNF. To elucidate if BDNF affects trafficking of GAT-1 in astrocytes, we generated and infected astrocytes with a functional mutant of the rat GAT-1 (rGAT-1) in which the hemagglutinin (HA) epitope...

  8. Transportation librarian's toolkit

    Science.gov (United States)

    2007-12-01

    The Transportation Librarians Toolkit is a product of the Transportation Library Connectivity pooled fund study, TPF- 5(105), a collaborative, grass-roots effort by transportation libraries to enhance information accessibility and professional expert...

  9. Fentanyl Enhances Hepatotoxicity of Paclitaxel via Inhibition of CYP3A4 and ABCB1 Transport Activity in Mice

    Science.gov (United States)

    Pan, Jia-Hao; Bi, Bing-Tian; Feng, Kun-Yao; Huang, Wan; Zeng, Wei-An

    2015-01-01

    Fentanyl, a potent opioid analgesic that is used to treat cancer pain, is commonly administered with paclitaxel in advanced tumors. However, the effect of fentanyl on the hepatotoxicity of paclitaxel and its potential mechanism of action is not well studied. The purpose of this study was to investigate the effect of fentanyl on the hepatotoxicity of paclitaxel and its potential mechanisms of action. Pharmacokinetic parameters of paclitaxel were tested using reversed phase high-performance liquid chromatography (RP-HPLC). Aspartate transaminase (AST), alanine aminotransferase (ALT), and mouse liver histopathology were examined. Moreover, the cytotoxicity of anti-carcinogens was examined using 1-(4, 5-dimethylthiazol-2-yl)-3,5-diphenylformazan (MTT), and the intracellular accumulation of doxorubicin and rhodamine 123 was detected by flow cytometry. Furthermore, the expression of ABCB1 and the activity of ABCB1 ATPase and CYP3A4 were also examined. In this study, the co-administration of fentanyl and paclitaxel prolonged the half-life (t1/2) of paclitaxel from 1.455 hours to 2.344 hours and decreased the clearance (CL) from 10.997 ml/h to 7.014 ml/h in mice. Fentanyl significantly increased the levels of ALT in mice to 88.2 U/L, which is more than 2-fold higher than the level detected in the control group, and it increased the histological damage in mouse livers. Furthermore, fentanyl enhanced the cytotoxicity of anti-carcinogens that are ABCB1 substrates and increased the accumulation of doxorubicin and rhodamine 123. Additionally, fentanyl stimulated ABCB1 ATPase activity and inhibited CYP3A4 activity in the liver microsomes of mice. Our study indicates that the obvious hepatotoxicity during this co-administration was due to the inhibition of CYP3A4 activity and ABCB1 transport activity. These findings suggested that the accumulation-induced hepatotoxicity of paclitaxel when it is combined with fentanyl should be avoided. PMID:26633878

  10. Out-of-equilibrium spin transport in mesoscopic superconductors.

    Science.gov (United States)

    Quay, C H L; Aprili, M

    2018-08-06

    The excitations in conventional superconductors, Bogoliubov quasi-particles, are spin-[Formula: see text] fermions but their charge is energy-dependent and, in fact, zero at the gap edge. Therefore, in superconductors (unlike normal metals) spin and charge degrees of freedom may be separated. In this article, we review spin injection into conventional superconductors and focus on recent experiments on mesoscopic superconductors. We show how quasi-particle spin transport and out-of-equilibrium spin-dependent superconductivity can be triggered using the Zeeman splitting of the quasi-particle density of states in thin-film superconductors with small spin-mixing scattering. Finally, we address the spin dynamics and the feedback of quasi-particle spin imbalances on the amplitude of the superconducting energy gap.This article is part of the theme issue 'Andreev bound states'. © 2018 The Author(s).

  11. Co-Transport of Polycyclic Aromatic Hydrocarbons by Motile Microorganisms Leads to Enhanced Mass Transfer under Diffusive Conditions

    DEFF Research Database (Denmark)

    Gilbert, Dorthea; Jakobsen, Hans H.; Winding, Anne

    2014-01-01

    as sink and source for polycyclic aromatic hydrocarbons (PAHs). This resulted in stable concentration gradients in water (>24 h). Adding the model organism Tetrahymena pyriformis to the experimental system enhanced PAH mass transfer up to hundred-fold (benzo[a]pyrene). Increasing mass transfer enhancement...

  12. Enhanced charge transport and photovoltaic performance of PBDTTT-C-T/PC70BM solar cells via UV-ozone treatment.

    Science.gov (United States)

    Adhikary, Prajwal; Venkatesan, Swaminathan; Adhikari, Nirmal; Maharjan, Purna P; Adebanjo, Olusegun; Chen, Jihua; Qiao, Qiquan

    2013-10-21

    In this work, the electron transport layer of PBDTTT-C-T/PC70BM polymer solar cells were subjected to UV-ozone treatment, leading to improved cell performances from 6.46% to 8.34%. The solar cell efficiency reached a maximum of 8.34% after an optimal 5 minute UV-ozone treatment, and then decreased if treated for a longer time. To the best of our knowledge, the mechanism behind the effects of UV-ozone treatment on the improvement of charge transport and cell performance is not fully understood. We have developed a fundamental understanding of the UV-ozone treatment mechanism, which explains both the enhancements in charge transport and photovoltaic performance at an optimal treatment time, and also the phenomenon whereby further treatment time leads to a drop in cell efficiency. Transient photocurrent measurements indicated that the cell charge transport times were 1370 ns, 770 ns, 832 ns, 867 ns, and 1150 ns for the 0 min, 5 min, 10 min, 15 min, and 20 min UV-ozone treatment times, respectively. Therefore the 5 min UV-ozone treatment time led to the shortest transport time and the most efficient charge transport in the cells. The 5 min UV-ozone treated sample exhibited the highest peak intensity (E2) in the Raman spectra of the treated films, at about 437 cm(-1), indicating that it possessed the best wurtzite phase crystallinity of the ZnO films. Further increasing the UV-ozone treatment time from 5 to 20 min induced the formation of p-type defects (e.g. interstitial oxygen atoms), pushing the ZnO Fermi-level further away from the vacuum level, and decreasing the wurtzite crystallinity.

  13. Two phloem nitrate transporters, NRT1.11 and NRT1.12, are important for redistributing xylem-borne nitrate to enhance plant growth.

    Science.gov (United States)

    Hsu, Po-Kai; Tsay, Yi-Fang

    2013-10-01

    This study of the Arabidopsis (Arabidopsis thaliana) nitrate transporters NRT1.11 and NRT1.12 reveals how the interplay between xylem and phloem transport of nitrate ensures optimal nitrate distribution in leaves for plant growth. Functional analysis in Xenopus laevis oocytes showed that both NRT1.11 and NRT1.12 are low-affinity nitrate transporters. Quantitative reverse transcription-polymerase chain reaction and immunoblot analysis showed higher expression of these two genes in larger expanded leaves. Green fluorescent protein and β-glucuronidase reporter analyses indicated that NRT1.11 and NRT1.12 are plasma membrane transporters expressed in the companion cells of the major vein. In nrt1.11 nrt1.12 double mutants, more root-fed (15)NO3(-) was translocated to mature and larger expanded leaves but less to the youngest tissues, suggesting that NRT1.11 and NRT1.12 are required for transferring root-derived nitrate into phloem in the major veins of mature and larger expanded leaves for redistributing to the youngest tissues. Distinct from the wild type, nrt1.11 nrt1.12 double mutants show no increase of plant growth at high nitrate supply. These data suggested that NRT1.11 and NRT1.12 are involved in xylem-to-phloem transfer for redistributing nitrate into developing leaves, and such nitrate redistribution is a critical step for optimal plant growth enhanced by increasing external nitrate.

  14. Aloe vera enhances the innate immune response of pacu (Piaractus mesopotamicus) after transport stress and combined heat killed Aeromonas hydrophila infection.

    Science.gov (United States)

    Zanuzzo, Fábio S; Sabioni, Rafael E; Montoya, Luz Natalia F; Favero, Gisele; Urbinati, Elisabeth C

    2017-06-01

    In this study, pacu (Piaractus mesopotamicus) were fed with diets containing Aloe vera for 10 days prior to transport stress and infection with heat killed Aeromonas hydrophila. A. vera is popular around the world due to its medicinal properties, including immunostimulatory effects which was observed in this study. The results show that transport causes immunosuppression, an effect that was prevented by A. vera. Specifically, A. vera prevented reductions of both leukocyte respiratory burst and hemolytic activity of complement system caused by transport. Further, fish fed with A. vera also showed significantly higher leukocyte respiratory burst, serum lysozyme concentrations and activity of complement system 24 h after bacterial infection. Additionally, we observed that A. vera may modulate the innate response through activation of complement system during bacterial immune stimulation. In summary, A. vera extract enhanced innate immune parameters and consequently the ability of fish to cope with pathogens following transport stress. These findings show that A. vera has promise for use in aquaculture and add further evidence that medicinal herbs added to fish feed assist to prevent disease outbreaks. Copyright © 2017 Elsevier Ltd. All rights reserved.

  15. Creatine Monohydrate Enhances Energy Status and Reduces Glycolysis via Inhibition of AMPK Pathway in Pectoralis Major Muscle of Transport-Stressed Broilers.

    Science.gov (United States)

    Zhang, Lin; Wang, Xiaofei; Li, Jiaolong; Zhu, Xudong; Gao, Feng; Zhou, Guanghong

    2017-08-16

    Creatine monohydrate (CMH) contributes to reduce transport-induced muscle rapid glycolysis and improve meat quality of broilers, but the underlying mechanism is still unknown. Therefore, this study aimed to investigate the molecular mechanisms underlying the ameliorative effects of CMH on muscle glycolysis metabolism of transported broilers during summer. The results showed that 3 h transport during summer elevated chicken live weight loss and plasma corticosterone concentration; decreased muscle concentrations of ATP, creatine, and energy charge value; increased muscle AMP concentration and AMP/ATP ratio; and upregulated muscle mRNA expression of LKB1 and AMPKα2, as well as protein expression of p-LKB1 Thr189 and p-AMPKα Thr172 , which subsequently resulted in rapid glycolysis in the pectoralis major muscle and consequent reduction of meat quality. Dietary addition of CMH at 1200 mg/kg ameliorated transport-induced rapid muscle glycolysis and reduction of meat quality via enhancement of the energy-buffering capacity of intramuscular phosphocreatine/creatine system and inhibition of AMPK pathway.

  16. Transport and pairing properties of helical edges with proximity induced superconductivity and ferromagnetism

    Energy Technology Data Exchange (ETDEWEB)

    Keidel, Felix; Burset, Pablo; Trauzettel, Bjoern [Institute of Theoretical Physics and Astrophysics, University of Wuerzburg, 97074 Wuerzburg (Germany); Crepin, Francois [Laboratoire de Physique Theorique de la Matiere Condensee, UPMC, Sorbonne Universites, 75252 Paris (France)

    2016-07-01

    The scientific interest in Quantum Spin Hall systems is far from declining. While these certainly are fascinating by themselves, there is plenty of new and exciting physics to arise when superconductivity and ferromagnetism are brought into the game. The strong constraint of helicity in the edge states of a two-dimensional topological insulator is responsible for an intimate relation between the allowed scattering processes in a hybrid junction and the parameters of the system, namely the superconducting order parameter and the magnetic field. In our work, we study a helical liquid in proximity to a conventional s-wave superconductor and ferromagnetic insulators by means of a Green's function analysis. The ferromagnet gives rise to sub-gap Andreev/Majorana bound states and non-local crossed Andreev reflection (CAR), both of which decisively affect the pairing and transport properties of the junction. As a result, the simple s-wave symmetry of the superconductor is enriched and unconventional odd-frequency triplet superconductivity emerges. Strikingly, we have identified a setup that favors CAR over electron co-tunneling and may allow for the indirect measurement of the symmetries of the superconducting order parameter.

  17. Two gap superconductivity in Ba{sub 0.55}K{sub 0.45}Fe{sub 2}As{sub 2} single crystals studied by the directional point-contact Andreev reflection spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Szabo, P.; Pribulova, Z. [Centre of Low Temperature Physics, IEP Slovak Academy of Sciences and P.J.Safarik University, Watsonova 47, SK-04001 Kosice (Slovakia); Pristas, G.; Bud' ko, S.L.; Canfield, P.C. [Ames Laboratory and Iowa State University, Ames, IA 50011 (United States); Samuely, P., E-mail: samuely@saske.s [Centre of Low Temperature Physics, IEP Slovak Academy of Sciences and P.J.Safarik University, Watsonova 47, SK-04001 Kosice (Slovakia)

    2009-10-15

    First directional point-contact Andreev reflection spectroscopy on the Ba{sub 0.55}K{sub 0.45}Fe{sub 2}As{sub 2} single crystals is presented. The spectra show significant differences when measured in the ab plane in comparison with those measured in the c direction. In the latter case no traces of superconducting energy gap could be found, just a reduced point-contact conductance persisting up to about 100 K and indicating reduced density of states. On the other hand within the ab plane two nodeless superconducting energy gaps DELTA{sub S}approx2-5 meV and DELTA{sub L}approx9-11 meV are detected.

  18. Improved performance of porous bio-anodes in microbial electrolysis cells by enhancing mass and charge transport

    NARCIS (Netherlands)

    Sleutels, T.H.J.A.; Lodder, R.; Hamelers, H.V.M.; Buisman, C.J.N.

    2009-01-01

    To create an efficient MEC high current densities and high coulombic efficiencies are required. The aim of this study was to increase cur-rent densities and coulombic efficiencies by influencing mass and charge transport in porous electrodes by: (i) introduction of a forced flow through the anode to

  19. Effect of permeation enhancers on the iontophoretic transport of metoprolol tartrate and the drug retention in skin.

    Science.gov (United States)

    Nair, Anroop; Vyas, Hiral; Shah, Jigar; Kumar, Ashok

    2011-01-01

    Utilization of chemical penetration enhancers in conjunction with iontophoresis is regarded as the most effective method to enhance the passage of molecules across the skin barrier. A systematic approach to enhance the transdermal delivery of metoprolol tartrate and the subsequent release of the drug depot in the skin was investigated. Gel formulations with proximate viscosity were prepared and assessed for the effect of polymers (carbopol, hydroxypropyl methyl cellulose, and methyl cellulose), permeation enhancers (5% w/w, sodium lauryl sulfate (SLS), dimethyl formamide, n-methyl-2-pyrrolidone, and polyethylene glycol 400), and the combination approach (permeation enhancers with iontophoresis-0.5 mA/cm² on the drug delivery. The flux values observed in passive (4.59-5.89 µg/cm²/h) and iontophoresis (37.99-41.57 µg/cm²/h) processes revealed that the permeation of metoprolol was not influenced by the polymers studied, under similar conditions, and further studies were carried out using carbopol gel as a representative polymer. Appreciable enhancement (~5-fold) in drug delivery was observed with SLS in the passive process while the optimum iontophoretic delivery condition ensured better delivery (~7-fold). Combination of iontophoresis with SLS further enhanced the drug delivery (~9-fold) and leads to noticeable drug retention in the skin as well. Moreover, the drug retained in the cutaneous layer of the skin eventually released over a period of time (5 days) and followed a near first order profile. This study concludes that the combination of iontophoresis with SLS augmented the metoprolol delivery and rendered skin drug depot, which eventually released over a period of time.

  20. Role of field-induced nanostructures, zippering and size polydispersity on effective thermal transport in magnetic fluids without significant viscosity enhancement

    Science.gov (United States)

    Vinod, Sithara; Philip, John

    2017-12-01

    Magnetic nanofluids or ferrofluids exhibit extraordinary field dependant tunable thermal conductivity (k), which make them potential candidates for microelectronic cooling applications. However, the associated viscosity enhancement under an external stimulus is undesirable for practical applications. Further, the exact mechanism of heat transport and the role of field induced nanostructures on thermal transport is not clearly understood. In this paper, through systematic thermal, rheological and microscopic studies in 'model ferrofluids', we demonstrate for the first time, the conditions to achieve very high thermal conductivity to viscosity ratio. Highly stable ferrofluids with similar crystallite size, base fluid, capping agent and magnetic properties, but with slightly different size distributions, are synthesized and characterized by X-ray diffraction, small angle X-ray scattering, transmission electron microscopy, dynamic light scattering, vibrating sample magnetometer, Fourier transform infrared spectroscopy and thermo-gravimetry. The average hydrodynamic diameters of the particles were 11.7 and 10.1 nm and the polydispersity indices (σ), were 0.226 and 0.151, respectively. We observe that the system with smaller polydispersity (σ = 0.151) gives larger k enhancement (130% for 150 G) as compared to the one with σ = 0.226 (73% for 80 G). Further, our results show that dispersions without larger aggregates and with high density interfacial capping (with surfactant) can provide very high enhancement in thermal conductivity, with insignificant viscosity enhancement, due to minimal interfacial losses. We also provide experimental evidence for the effective heat conduction (parallel mode) through a large number of space filling linear aggregates with high aspect ratio. Microscopic studies reveal that the larger particles act as nucleating sites and facilitate lateral aggregation (zippering) of linear chains that considerably reduces the number density of space

  1. Magnetic Field Enhancement of Heat Transport in the 2D Heisenberg Antiferromagnet K_2V_3O_8

    Science.gov (United States)

    Sales, B. C.; Lumsden, M. D.; Nagler, S. E.; Mandrus, D.; Jin, R.

    2002-03-01

    The thermal conductivity and heat capacity of single crystals of the spin 1/2 quasi-2D Heisenberg antiferromagnet K_2V_3O8 have been measured from 1.9 to 300 K in magnetic fields from 0 to 8T. The data are consistent with resonant scattering of phonons by magnons near the zone boundary and heat transport by long wavelength magnons. The magnon heat transport only occurs after the small anisotropic gap at k=0 is closed by the application of a magnetic field. The low temperature thermal conductivity increases linearly with magnetic field after the gap has been closed. Oak Ridge National Laboratory is managed by UT-Battelle LLC for the U.S. Department of Energy under Contract No. DE-AC05-00R22725.

  2. Evidence for a poloidally localized enhancement of radial transport in the scrape-off layer of the Tore Supra tokamak

    Czech Academy of Sciences Publication Activity Database

    Gunn, J. P.; Boucher, C.; Dionne, M.; Ďuran, Ivan; Fuchs, Vladimír; Loarer, T.; Nanobashvili, I.; Pánek, Radomír; Pascal, J.-Y.; Saint-Laurent, F.; Stöckel, Jan; Van Rompuy, T.; Zagórski, R.; Adámek, Jiří; Bucalossi, J.; Dejarnac, Renaud; Devynck, P.; Hertout, P.; Hron, Martin; Lebrun, G.; Moreau, P.; Rimini, F.; Sarkissian, A.; Van Oost, G.

    363-365, - (2007), s. 484-490 ISSN 0022-3115. [International Conference on Plasma-Surface Interactions in Controlled Fusion Devices/17th./. Hefei, 22.05.2006-26.05. 2006] R&D Projects: GA ČR GP202/03/P062 Institutional research plan: CEZ:AV0Z20430508 Keywords : Cross-field transport * Edge plasma * Plasma flow * Tore Supra Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 1.643, year: 2007

  3. Development of Parallel Computing Framework to Enhance Radiation Transport Code Capabilities for Rare Isotope Beam Facility Design

    Energy Technology Data Exchange (ETDEWEB)

    Kostin, Mikhail [Michigan State Univ., East Lansing, MI (United States); Mokhov, Nikolai [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Niita, Koji [Research Organization for Information Science and Technology, Ibaraki-ken (Japan)

    2013-09-25

    A parallel computing framework has been developed to use with general-purpose radiation transport codes. The framework was implemented as a C++ module that uses MPI for message passing. It is intended to be used with older radiation transport codes implemented in Fortran77, Fortran 90 or C. The module is significantly independent of radiation transport codes it can be used with, and is connected to the codes by means of a number of interface functions. The framework was developed and tested in conjunction with the MARS15 code. It is possible to use it with other codes such as PHITS, FLUKA and MCNP after certain adjustments. Besides the parallel computing functionality, the framework offers a checkpoint facility that allows restarting calculations with a saved checkpoint file. The checkpoint facility can be used in single process calculations as well as in the parallel regime. The framework corrects some of the known problems with the scheduling and load balancing found in the original implementations of the parallel computing functionality in MARS15 and PHITS. The framework can be used efficiently on homogeneous systems and networks of workstations, where the interference from the other users is possible.

  4. Expression of TpNRAMP5, a metal transporter from Polish wheat (Triticum polonicum L.), enhances the accumulation of Cd, Co and Mn in transgenic Arabidopsis plants.

    Science.gov (United States)

    Peng, Fan; Wang, Chao; Zhu, Jianshu; Zeng, Jian; Kang, Houyang; Fan, Xing; Sha, Lina; Zhang, Haiqin; Zhou, Yonghong; Wang, Yi

    2018-06-01

    TpRNAMP5 is mainly expressed in the plasma membrane of roots and basal stems. It functions as a metal transporter for Cd, Mn and Co accumulation. Numerous natural resistance-associated macrophage proteins (NRAMPs) have been functionally identified in various plant species, including Arabidopsis, rice, soybean and tobacco, but no information is available on NRAMP genes in wheat. In this study, we isolated a TpNRAMP5 from dwarf Polish wheat (DPW, Triticum polonicum L.), a species with high tolerance to Cd and Zn. Expression pattern analysis revealed that TpNRAMP5 is mainly expressed in roots and basal stems of DPW. TpNRAMP5 was localized at the plasma membrane of Arabidopsis leaf protoplast. Expression of TpNRAMP5 in yeast significantly increased yeast sensitivity to Cd and Co, but not Zn, and enhanced Cd and Co concentrations. Expression of TpNRAMP5 in Arabidopsis significantly increased Cd, Co and Mn concentrations in roots, shoots and whole plants, but had no effect on Fe and Zn concentrations. These results indicate that TpNRAMP5 is a metal transporter enhancing the accumulation of Cd, Co and Mn, but not Zn and Fe. Genetic manipulation of TpNRAMP5 can be applied in the future to limit the transfer of Cd from soil to wheat grains, thereby protecting human health.

  5. Numerical modelling of biophysicochemical effects on multispecies reactive transport in porous media involving Pseudomonas putida for potential microbial enhanced oil recovery application.

    Science.gov (United States)

    Sivasankar, P; Rajesh Kanna, A; Suresh Kumar, G; Gummadi, Sathyanarayana N

    2016-07-01

    pH and resident time of injected slug plays a critical role in characterizing the reservoir for potential microbial enhanced oil recovery (MEOR) application. To investigate MEOR processes, a multispecies (microbes-nutrients) reactive transport model in porous media was developed by coupling kinetic and transport model. The present work differs from earlier works by explicitly determining parametric values required for kinetic model by experimental investigations using Pseudomonas putida at different pH conditions and subsequently performing sensitivity analysis of pH, resident time and water saturation on concentrations of microbes, nutrients and biosurfactant within reservoir. The results suggest that nutrient utilization and biosurfactant production are found to be maximum at pH 8 and 7.5 respectively. It is also found that the sucrose and biosurfactant concentrations are highly sensitive to pH rather than reservoir microbial concentration, while at larger resident time and water saturation, the microbial and nutrient concentrations were lesser due to enhanced dispersion. Copyright © 2016 Elsevier Ltd. All rights reserved.

  6. The B7-1 cytoplasmic tail enhances intracellular transport and mammalian cell surface display of chimeric proteins in the absence of a linear ER export motif.

    Directory of Open Access Journals (Sweden)

    Yi-Chieh Lin

    Full Text Available Membrane-tethered proteins (mammalian surface display are increasingly being used for novel therapeutic and biotechnology applications. Maximizing surface expression of chimeric proteins on mammalian cells is important for these applications. We show that the cytoplasmic domain from the B7-1 antigen, a commonly used element for mammalian surface display, can enhance the intracellular transport and surface display of chimeric proteins in a Sar1 and Rab1 dependent fashion. However, mutational, alanine scanning and deletion analysis demonstrate the absence of linear ER export motifs in the B7 cytoplasmic domain. Rather, efficient intracellular transport correlated with the presence of predicted secondary structure in the cytoplasmic tail. Examination of the cytoplasmic domains of 984 human and 782 mouse type I transmembrane proteins revealed that many previously identified ER export motifs are rarely found in the cytoplasmic tail of type I transmembrane proteins. Our results suggest that efficient intracellular transport of B7 chimeric proteins is associated with the structure rather than to the presence of a linear ER export motif in the cytoplasmic tail, and indicate that short (less than ~ 10-20 amino acids and unstructured cytoplasmic tails should be avoided to express high levels of chimeric proteins on mammalian cells.

  7. Effect of d-wave pairing symmetry in transport properties of silicene-based superconductor junction

    Science.gov (United States)

    Vosoughi-nia, S.; Rashedi, G.; hajati, Y.

    2018-06-01

    We theoretically study the tunneling conductance of a normal/d-wave superconductor silicene junction using Blonder-Tinkham-Klapwijk (BTK) formalism. We discuss how the conductance spectra are affected by changing the chemical potential (μN) in the normal silicene region. It is obtained that the amplitude of the spin/valley-dependent Andreev reflection (AR) and charge conductance (G) of the junction can be strongly modulated by the orientation angle of superconductive gap (β) and perpendicular electric field (Ez). We demonstrate that the charge conductance exhibits an oscillatory behavior as a function of β by a period of π/2. Remarkably, variation of μN strongly modifies the amplitude of the oscillations and periodically there are transport gaps in the G - β oscillations for a range of μN. These findings suggest that one may experimentally tune the transport properties of the junction through changing β, Ez and μN.

  8. Foxtail Millet [Setaria italica (L. Beauv.] Grown under Low Nitrogen Shows a Smaller Root System, Enhanced Biomass Accumulation, and Nitrate Transporter Expression

    Directory of Open Access Journals (Sweden)

    Faisal Nadeem

    2018-02-01

    Full Text Available Foxtail millet (FM [Setaria italica (L. Beauv.] is a grain and forage crop well adapted to nutrient-poor soils. To date little is known how FM adapts to low nitrogen (LN at the morphological, physiological, and molecular levels. Using the FM variety Yugu1, we found that LN led to lower chlorophyll contents and N concentrations, and higher root/shoot and C/N ratios and N utilization efficiencies under hydroponic culture. Importantly, enhanced biomass accumulation in the root under LN was in contrast to a smaller root system, as indicated by significant decreases in total root length; crown root number and length; and lateral root number, length, and density. Enhanced carbon allocation toward the root was rather for significant increases in average diameter of the LN root, potentially favorable for wider xylem vessels or other anatomical alterations facilitating nutrient transport. Lower levels of IAA and CKs were consistent with a smaller root system and higher levels of GA may promote root thickening under LN. Further, up-regulation of SiNRT1.1, SiNRT2.1, and SiNAR2.1 expression and nitrate influx in the root and that of SiNRT1.11 and SiNRT1.12 expression in the shoot probably favored nitrate uptake and remobilization as a whole. Lastly, more soluble proteins accumulated in the N-deficient root likely as a result of increases of N utilization efficiencies. Such “excessive” protein-N was possibly available for shoot delivery. Thus, FM may preferentially transport carbon toward the root facilitating root thickening/nutrient transport and allocate N toward the shoot maximizing photosynthesis/carbon fixation as a primary adaptive strategy to N limitation.

  9. Foxtail Millet [Setaria italica (L.) Beauv.] Grown under Low Nitrogen Shows a Smaller Root System, Enhanced Biomass Accumulation, and Nitrate Transporter Expression.

    Science.gov (United States)

    Nadeem, Faisal; Ahmad, Zeeshan; Wang, Ruifeng; Han, Jienan; Shen, Qi; Chang, Feiran; Diao, Xianmin; Zhang, Fusuo; Li, Xuexian

    2018-01-01

    Foxtail millet (FM) [ Setaria italica (L.) Beauv.] is a grain and forage crop well adapted to nutrient-poor soils. To date little is known how FM adapts to low nitrogen (LN) at the morphological, physiological, and molecular levels. Using the FM variety Yugu1, we found that LN led to lower chlorophyll contents and N concentrations, and higher root/shoot and C/N ratios and N utilization efficiencies under hydroponic culture. Importantly, enhanced biomass accumulation in the root under LN was in contrast to a smaller root system, as indicated by significant decreases in total root length; crown root number and length; and lateral root number, length, and density. Enhanced carbon allocation toward the root was rather for significant increases in average diameter of the LN root, potentially favorable for wider xylem vessels or other anatomical alterations facilitating nutrient transport. Lower levels of IAA and CKs were consistent with a smaller root system and higher levels of GA may promote root thickening under LN. Further, up-regulation of SiNRT1.1, SiNRT2.1, and SiNAR2.1 expression and nitrate influx in the root and that of SiNRT1.11 and SiNRT1.12 expression in the shoot probably favored nitrate uptake and remobilization as a whole. Lastly, more soluble proteins accumulated in the N-deficient root likely as a result of increases of N utilization efficiencies. Such "excessive" protein-N was possibly available for shoot delivery. Thus, FM may preferentially transport carbon toward the root facilitating root thickening/nutrient transport and allocate N toward the shoot maximizing photosynthesis/carbon fixation as a primary adaptive strategy to N limitation.

  10. Enhancing the intestinal absorption of low molecular weight chondroitin sulfate by conjugation with α-linolenic acid and the transport mechanism of the conjugates.

    Science.gov (United States)

    Xiao, Yuliang; Li, Pingli; Cheng, Yanna; Zhang, Xinke; Sheng, Juzheng; Wang, Decai; Li, Juan; Zhang, Qian; Zhong, Chuanqing; Cao, Rui; Wang, Fengshan

    2014-04-25

    The purpose of this report was to demonstrate the effect of amphiphilic polysaccharides-based self-assembling micelles on enhancing the oral absorption of low molecular weight chondroitin sulfate (LMCS) in vitro and in vivo, and identify the transepithelial transport mechanism of LMCS micelles across the intestinal barrier. α-Linolenic acid-low molecular weight chondroitin sulfate polymers(α-LNA-LMCS) were successfully synthesized, and characterized by FTIR, (1)HNMR, TGA/DSC, TEM, laser light scattering and zeta potential. The significant oral absorption enhancement and elimination half-life (t₁/₂) extension of LNA-LMCS2 in rats were evidenced by intragastric administration in comparison with CS and LMCS. Caco-2 transport studies demonstrated that the apparent permeability coefficient (Papp) of LNA-LMCS2 was significantly higher than that of CS and LMCS (p<0.001), and no significant effects on the overall integrity of the monolayer were observed during the transport process. In addition, α-LNA-LMCS micelles accumulated around the cell membrane and intercellular space observed by confocal laser scanning microscope (CLSM). Furthermore, evident alterations in the F-actin cytoskeleton were detected by CLSM observation following the treatment of the cell monolayers with α-LNA-LMCS micelles, which further certified the capacity of α-LNA-LMCS micelles to open the intercellular tight junctions rather than disrupt the overall integrity of the monolayer. Therefore, LNA-LMCS2 with low cytotoxicity and high bioavailability might be a promising substitute for CS in clinical use, such as treating osteoarthritis, atherosclerosis, etc. Copyright © 2014 Elsevier B.V. All rights reserved.

  11. BoALMT1, an Al-Induced Malate Transporter in Cabbage, Enhances Aluminum Tolerance in Arabidopsis thaliana

    OpenAIRE

    Zhang, Lei; Wu, Xin-Xin; Wang, Jinfang; Qi, Chuandong; Wang, Xiaoyun; Wang, Gongle; Li, Mingyue; Li, Xingsheng; Guo, Yang-Dong

    2018-01-01

    Aluminum (Al) is present in approximately 50% of the arable land worldwide and is regarded as the main limiting factor of crop yield on acidic soil. Al-induced root malate efflux plays an important role in the Al tolerance of plants. Here, the aluminum induced malate transporter BoALMT1 (KF322104) was cloned from cabbage (Brassica oleracea). BoALMT1 showed higher expression in roots than in shoots. The expression of BoALMT1 was specifically induced by Al treatment, but not the trivalent catio...

  12. Expression of Na+/glucose co-transporter 1 (SGLT1) is enhanced by supplementation of the diet of weaning piglets with artificial sweeteners.

    Science.gov (United States)

    Moran, Andrew W; Al-Rammahi, Miran A; Arora, Daleep K; Batchelor, Daniel J; Coulter, Erin A; Daly, Kristian; Ionescu, Catherine; Bravo, David; Shirazi-Beechey, Soraya P

    2010-09-01

    In an intensive livestock production, a shorter suckling period allows more piglets to be born. However, this practice leads to a number of disorders including nutrient malabsorption, resulting in diarrhoea, malnutrition and dehydration. A number of strategies have been proposed to overcome weaning problems. Artificial sweeteners, routinely included in piglets' diet, were thought to enhance feed palatability. However, it is shown in rodent models that when included in the diet, they enhance the expression of Na+/glucose co-transporter (SGLT1) and the capacity of the gut to absorb glucose. Here, we show that supplementation of piglets' feed with a combination of artificial sweeteners saccharin and neohesperidin dihydrochalcone enhances the expression of SGLT1 and intestinal glucose transport function. Artificial sweeteners are known to act on the intestinal sweet taste receptor T1R2/T1R3 and its partner G-protein, gustducin, to activate pathways leading to SGLT1 up-regulation. Here, we demonstrate that T1R2, T1R3 and gustducin are expressed together in the enteroendocrine cells of piglet intestine. Furthermore, gut hormones secreted by the endocrine cells in response to dietary carbohydrates, glucagon-like peptides (GLP)-1, GLP-2 and glucose-dependent insulinotrophic peptide (GIP), are co-expressed with type 1 G-protein-coupled receptors (T1R) and gustducin, indicating that L- and K-enteroendocrine cells express these taste elements. In a fewer endocrine cells, T1R are also co-expressed with serotonin. Lactisole, an inhibitor of human T1R3, had no inhibitory effect on sweetener-induced SGLT1 up-regulation in piglet intestine. A better understanding of the mechanism(s) involved in sweetener up-regulation of SGLT1 will allow the identification of nutritional targets with implications for the prevention of weaning-related malabsorption.

  13. Optimization of an Electron Transport Layer to Enhance the Power Conversion Efficiency of Flexible Inverted Organic Solar Cells

    Directory of Open Access Journals (Sweden)

    Lee Kang Hyuck

    2010-01-01

    Full Text Available Abstract The photovoltaic (PV performance of flexible inverted organic solar cells (IOSCs with an active layer consisting of a blend of poly(3-hexylthiophene and [6, 6]-phenyl C61-butlyric acid methyl ester was investigated by varying the thicknesses of ZnO seed layers and introducing ZnO nanorods (NRs. A ZnO seed layer or ZnO NRs grown on the seed layer were used as an electron transport layer and pathway to optimize PV performance. ZnO seed layers were deposited using spin coating at 3,000 rpm for 30 s onto indium tin oxide (ITO-coated polyethersulphone (PES substrates. The ZnO NRs were grown using an aqueous solution method at a low temperature (90°C. The optimized device with ZnO NRs exhibited a threefold increase in PV performance compared with that of a device consisting of a ZnO seed layer without ZnO NRs. Flexible IOSCs fabricated using ZnO NRs with improved PV performance may pave the way for the development of PV devices with larger interface areas for effective exciton dissociation and continuous carrier transport paths.

  14. Multi-year composite view of ozone enhancements and stratosphere-to-troposphere transport in dry intrusions of northern hemisphere extratropical cyclones

    Science.gov (United States)

    Jaegle, L.; Wood, R.; Wargan, K.

    2017-12-01

    We examine the role of extratropical cyclones in stratosphere-to-troposphere (STT) exchange by using cyclone-centric composites of O3 retrievals from the Microwave Limb Sounder (MLS) and the Tropospheric Emission Spectrometer (TES) onboard the Aura satellite and contrasting them to composites obtained with Modern-Era Retrospective-analysis for Research and Applications (MERRA and MERRA-2) as well as with the GEOS-Chem chemical transport model. MERRA sea level pressure fields are used to identify 15,978 extratropical cyclones in the northern hemisphere (NH) between 2005 and 2012. The lowermost stratosphere (261 hPa) and middle troposphere (424 hPa) composites of these cyclones feature a distinct 1,000 km wide O3 enhancement in the dry intrusion to the southwest of the cyclone center, coinciding with a lowered tropopause, enhanced potential vorticity, and decreased water vapor. In the lowermost stratosphere, MLS composites show that the dry intrusion O3 enhancements reach a 210 ppbv maximum in April. In the middle troposphere, TES composites display dry intrusion maximum O3 enhancements of 27 ppbv in May. The magnitude and seasonality of these enhancements are captured by MERRA and MERRA-2, but GEOS-Chem is a factor of two too low. The MERRA-2 composites show that the O3-rich dry intrusion forms a coherent and vertically aligned structure between 300 and 800 hPa, wrapping cyclonically with the warm conveyor belt. In winter and spring dry intrusions, O3 is enhanced by 100 pbbv or 100-130% relative to background conditions at 300 hPa, with a significant contribution reaching pressure altitudes below 500 hPa (6-20 ppbv or 15-30% enhancement). We calculate that extratropical cyclones result in a STT flux of 119 Tg O3 yr-1, accounting for 42% of the annual NH O3 extratropical STT flux. The STT flux in cyclones is highest in spring and displays a strong dependence on westerly 300 hPa wind speeds.

  15. SPIN1, negatively regulated by miR-148/152, enhances Adriamycin resistance via upregulating drug metabolizing enzymes and transporter in breast cancer.

    Science.gov (United States)

    Chen, Xu; Wang, Ya-Wen; Gao, Peng

    2018-05-09

    Spindlin1 (SPIN1), a protein highly expressed in several human cancers, has been correlated with tumorigenesis and development. Alterations of drug metabolizing enzymes and drug transporters are major determinants of chemoresistance in tumor cells. However, whether the metabolizing enzymes and transporters are under the control of SPIN1 in breast cancer chemoresistance has not yet been defined. SPIN1 expression in breast cancer cells and tissues was detected by quantitative real-time PCR (qRT-PCR) and immunohistochemistry. Chemosensitivity assays in vitro and in vivo were performed to determine the effect of SPIN1 on Adriamycin resistance. Downstream effectors of SPIN1 were screened by microarray and confirmed by qRT-PCR and Western blot. Luciferase assay and Western blot were used to identify miRNAs regulating SPIN1. We showed that SPIN1 was significantly elevated in drug-resistant breast cancer cell lines and tissues, compared with the chemosensitive ones. SPIN1 enhanced Adriamycin resistance of breast cancer cells in vitro, and downregulation of SPIN1 by miRNA could decrease Adriamycin resistance in vivo. Mechanistically, drug metabolizing enzymes and transporter CYP2C8, UGT2B4, UGT2B17 and ABCB4 were proven to be downstream effectors of SPIN1. Notably, SPIN1 was identified as a direct target of the miR-148/152 family (miR-148a-3p, miR-148b-3p and miR-152-3p). As expected, miR-148a-3p, miR-148b-3p or miR-152-3p could increase Adriamycin sensitivity in breast cancer cells in vitro. Moreover, high expression of SPIN1 or low expression of the miR-148/152 family predicted poorer survival in breast cancer patients. Our results establish that SPIN1, negatively regulated by the miR-148/152 family, enhances Adriamycin resistance in breast cancer via upregulating the expression of drug metabolizing enzymes and drug transporter.

  16. Enhanced rotation velocities and electric fields, sub-neoclassical energy transport and density pinch from revisited neoclassical theory

    International Nuclear Information System (INIS)

    Rogister, A.

    1998-01-01

    We show that the large negative radial electric fields which are measured in front of the separatrix in H-mode discharges are easily explainable on the basis of the rigorous 'revisited' neoclassical theory, including finite Larmor radii and inertia effects that was published earlier (Rogister A 1994 Phys. Plasmas 1 619); the same theory naturally leads to sub-neoclassical energy transport and novel particle pinch terms. The calculation has so far been developed only in the high collisionality regime: step sizes comparable to gradient-scale sizes are therefore not required to explain observed properties! Based on the analysis, we conclude that the radial electric field profile develops a well in front of the separatrix when the plasma is unable to sustain ambipolar flows otherwise. (author)

  17. Enhanced permanganate in situ chemical oxidation through MnO2 particle stabilization: evaluation in 1-D transport systems.

    Science.gov (United States)

    Crimi, Michelle; Quickel, Mark; Ko, Saebom

    2009-02-27

    In situ chemical oxidation using permanganate is an increasingly employed approach to organic contaminant remediation at hazardous waste sites. Manganese dioxide (MnO2) particles form as a by-product of the reaction of permanganate with contaminants and naturally-reduced subsurface materials. These particles are of interest because they have the potential to deposit in the subsurface and impact the flow regime in/around permanganate injection, including the well screen, filter pack, and the surrounding subsurface formation. Control of these particles can allow for improved oxidant injection and transport, and contact between the oxidant and contaminants of concern. Sodium hexametaphosphate (HMP) has previously been identified as a promising aid to stabilize MnO2 in solution when included in the oxidizing solution, increasing the potential to inhibit particle deposition and impact subsurface flow. The goal of the experimental studies described herein was to investigate the ability of HMP to prevent particle deposition in transport studies using four different types of porous media. Permanganate was delivered to a contaminant source zone (trichloroethylene) located within four different media types with variations in sand, clay, organic carbon, and iron oxides (as goethite) content. Deposition of MnO2 within the columns was quantified with distance from the source zone. Experiments were repeated in replicate columns with the inclusion of HMP directly with the oxidant delivery solution, and MnO2 deposition was again quantified. While total MnO2 deposition within the 60 cm columns did not change significantly with the addition of HMP, deposition within the contaminant source zone decreased by 25-85%, depending on the specific media type. The greatest differences in deposition were observed in the goethite-containing and clay-containing columns. Columns containing these two media types experienced completely plugged flow in the oxidant-only delivery systems; however

  18. Alternative transcription of sodium/bicarbonate transporter SLC4A7 gene enhanced by single nucleotide polymorphisms.

    Science.gov (United States)

    Park, Hae Jeong; Lee, Soojung; Ju, Eunji; Jones, Jayre A; Choi, Inyeong

    2017-03-01

    Genome-wide association studies have identified the single nucleotide polymorphism (SNP) rs3278 in the human SLC4A7 gene as one of the marker loci for addiction vulnerability. This marker is located in an intron of the gene, and its genomic role has been unknown. In this study, we examined rs3278 and three adjacent SNPs prevalent in alcoholics for their effects on an alternative promoter that would lead to the production of the NH 2 -terminally truncated protein NBCn1ΔN450, missing the first 450 amino acids. Analysis of the transcription start site database and a promoter prediction algorithm identified a cluster of three promoters in intron 7 and two short CpG-rich sites in intron 6. The promoter closest to rs3278 showed strong transcription activity in luciferase reporter gene assays. Major-to-minor allele substitution at rs3278 resulted in increased transcription activity. Equivalent substitutions at adjacent rs3772723 (intron 7) and rs13077400 (exon 8) had negligible effect; however, the substitution at nonsynonymous rs3755652 (exon 8) increased the activity by more than twofold. The concomitant substitution at rs3278/rs3755652 produced an additive effect. The rs3755652 had more profound effects on the promoter than the upstream regulatory CpG sites. The amino acid change E326K caused by rs3755652 had negligible effect on transporter function. In HEK 293 cells, NBCn1ΔN450 was expressed in plasma membranes, but at significantly lower levels than the nontruncated NBCn1-E. The pH change mediated by NBCn1ΔN450 was also low. We conclude that rs3278 and rs3755652 stimulate an alternative transcription of the SLC4A7 gene, increasing the production of a defective transporter. Copyright © 2017 the American Physiological Society.

  19. Enhancing Bioremediation of Oil-contaminated Soils by Controlling Nutrient Transport using Dual Characteristics of Soil Pore Structure

    Science.gov (United States)

    Mori, Y.; Suetsugu, A.; Matsumoto, Y.; Fujihara, A.; Suyama, K.; Miyamoto, T.

    2012-12-01

    Soil structure is heterogeneous with cracks or macropores allowing bypass flow, which may lead to applied chemicals avoiding interaction with soil particles or the contaminated area. We investigated the bioremediation efficiency of oil-contaminated soils by applying suction at the bottom of soil columns during bioremediation. Unsaturated flow conditions were investigated so as to avoid bypass flow and achieve sufficient dispersion of chemicals in the soil column. The boundary conditions at the bottom of the soil columns were 0 kPa and -3 kPa, and were applied to a volcanic ash soil with and without macropores. Unsaturated flow was achieved with -3 kPa and an injection rate of 1/10 of the saturated hydraulic conductivity. The resultant biological activities of the effluent increased dramatically in the unsaturated flow with macropores condition. Unsaturated conditions prevented bypass flow and allowed dispersion of the injected nutrients. Unsaturated flow achieved 60-80% of saturation, which enhanced biological activity in the soil column. Remediation results were better for unsaturated conditions because of higher biological activity. Moreover, unsaturated flow with macropores achieved uniform remediation efficiency from upper through lower positions in the column. Finally, taking the applied solution volume into consideration, unsaturated flow with -3 kPa achieved 10 times higher efficiency when compared with conventional saturated flow application. These results suggest that effective use of nutrients or remediation chemicals is possible by avoiding bypass flow and enhancing biological activity using relatively simple and inexpensive techniques.

  20. Enhanced THz emission from c-plane InxGa1-xN due to piezoelectric field-induced electron transport

    Science.gov (United States)

    Woodward, Nathaniel; Gallinat, C.; Rodak, L. E.; Metcalfe, G. D.; Shen, H.; Wraback, M.

    2012-05-01

    Enhanced terahertz emission from coherently strained InxGa1-xN epilayers on GaN is observed, which exceeds or is comparable to bulk InAs emission at pump wavelengths of 400 nm or 800 nm, respectively. The inverted terahertz waveform from the InxGa1-xN/GaN heterostructure indicates that the dominant terahertz generation mechanism is electron acceleration toward the InxGa1-xN surface in an internal electric field primarily associated with piezoelectric polarization charge at the heterointerface, rather than diffusive transport away from the surface typically observed in bulk semiconductors. The persistence of the inverted waveform for 266 nm excitation provides evidence of ultrafast electron relaxation via LO phonon emission.

  1. A chimeric protein of aluminum-activated malate transporter generated from wheat and Arabidopsis shows enhanced response to trivalent cations.

    Science.gov (United States)

    Sasaki, Takayuki; Tsuchiya, Yoshiyuki; Ariyoshi, Michiyo; Ryan, Peter R; Yamamoto, Yoko

    2016-07-01

    TaALMT1 from wheat (Triticum aestivum) and AtALMT1 from Arabidopsis thaliana encode aluminum (Al)-activated malate transporters, which confer acid-soil tolerance by releasing malate from roots. Chimeric proteins from TaALMT1 and AtALMT1 (Ta::At, At::Ta) were previously analyzed in Xenopus laevis oocytes. Those studies showed that Al could activate malate efflux from the Ta::At chimera but not from At::Ta. Here, functions of TaALMT1, AtALMT1 and the chimeric protein Ta::At were compared in cultured tobacco BY-2 cells. We focused on the sensitivity and specificity of their activation by trivalent cations. The activation of malate efflux by Al was at least two-fold greater in the chimera than the native proteins. All proteins were also activated by lanthanides (erbium, ytterbium, gadolinium, and lanthanum), but the chimera again released more malate than TaALMT1 or AtALMT1. In Xenopus oocytes, Al, ytterbium, and erbium activated inward currents from the native TaALMT1 and the chimeric protein, but gadolinium only activated currents from the chimera. Lanthanum inhibited currents from both proteins. These results demonstrated that function of the chimera protein was altered compared to the native proteins and was more responsive to a range of trivalent cations when expressed in plant cells. Copyright © 2016 Elsevier B.V. All rights reserved.

  2. Comparing FRACHEM and TOUGHREACT for reactive transport modelingof brine-rock interactions in enhanced geothermal systems (EGS)

    Energy Technology Data Exchange (ETDEWEB)

    Andre, L.; Spycher, N.; Xu, T.; Pruess, K.; Vuataz, F.-D.

    2005-11-15

    Coupled modelling of fluid flow and reactive transport ingeothermal systems is challenging because of reservoir conditions such ashigh temperatures, elevated pressures and sometimes high salinities ofthe formation fluids. Thermal hydrological-chemical (THC) codes, such asFRACHEM and TOUGHREACT, have been developed to evaluate the long-termhydrothermal and chemical evolution of exploited reservoirs. In thisstudy, the two codes were applied to model the same geothermal reservoir,to forecast reservoir evolution using respective thermodynamic andkinetic input data. A recent (unreleased) TOUGHREACT version allows theuse of either an extended Debye-Hu?ckel or Pitzer activity model forcalculating activity coefficients, while FRACHEM was designed to use thePitzer formalism. Comparison of models results indicate that differencesin thermodynamic equilibrium constants, activity coefficients andkinetics models can result in significant differences in predictedmineral precipitation behaviour and reservoir-porosity evolution.Differences in the calculation schemes typically produce less differencein model outputs than differences in input thermodynamic and kineticdata, with model results being particularly sensitive to differences inion-interaction parameters for highsalinity systems.

  3. d-Fructose Modification Enhanced Internalization of Mixed Micelles in Breast Cancer Cells via GLUT5 Transporters.

    Science.gov (United States)

    Zhou, Xu; Qin, Xianyan; Gong, Tao; Zhang, Zhi-Rong; Fu, Yao

    2017-07-01

    d-Fructose modified poly(ε-caprolactone)-polyethylene glycol (PCL-PEG-Fru) diblock amphiphile is synthesized via Cu(I)-catalyzed click chemistry, which self-assembles with D-α-tocopheryl polyethylene glycol 1000 succinate (TPGS) into PCL-PEG-Fru/TPGS mixed micelles (PPF MM). It has been proven that glucose transporter (GLUT)5 is overexpressed in MCF-7 cells other than L929 cells. In this study, PPF MM exhibit a significantly higher uptake efficiency than fructose-free PCL-PEG-N 3 /TPGS mixed micelles in both 2D MCF-7 cells and 3D tumor spheroids. Also, the presence of free d-fructose competitively inhibits the internalization of PPF MM in MCF-7 cells other than L929 cells. PPF MM show selective tumor accumulation in MCF-7 breast tumor bearing mice xenografts. Taken together, PPF MM represent a promising nanoscale carrier system to achieve GLUT5-mediated cell specific delivery in cancer therapy. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Molecular Dynamics Simulation for Surface and Transport Properties of Fluorinated Silica Nanoparticles in Water or Decane: Application to Gas Recovery Enhancement

    Directory of Open Access Journals (Sweden)

    Sepehrinia Kazem

    2017-05-01

    Full Text Available Determination of surface and transport properties of nanoparticles (NPs is essential for a variety of applications in enhanced oil and gas recoveries. In this paper, the impact of the surface chemistry of silica NPs on their hydro- and oleo-phobic properties as well as their transport properties are investigated in water or decane using molecular dynamics simulation. Trifluoromethyl or pentafluoroethyl groups as water and oil repellents are placed on the NPs. It is found that the density and residence time of liquid molecules around the NPs are modulated considerably with the existence of the functional groups on the NPs’ surfaces. Also, much larger density fluctuations for liquids close to the surface of the NPs are observed when the number of the groups on the NPs increases, indicating increased hydrophobicity. In addition, the diffusion coefficient of the NPs in either water or decane increases with increasing the number or length of the fluorocarbon chains, demonstrating non-Brownian behavior for the NPs. The surface chemistry imparts a considerable contribution on the diffusion coefficient of the NPs. Finally, potential of mean force calculations are undertaken. It is observed that the free energy of adsorption of the NPs on a mineral surface is more favorable than that of the aggregation of the NPs, which suggests the NPs adsorb preferably on the mineral surface.

  5. Transport Statistics - Transport - UNECE

    Science.gov (United States)

    Sustainable Energy Statistics Trade Transport Themes UNECE and the SDGs Climate Change Gender Ideas 4 Change UNECE Weekly Videos UNECE Transport Areas of Work Transport Statistics Transport Transport Statistics About us Terms of Reference Meetings and Events Meetings Working Party on Transport Statistics (WP.6

  6. Advances in applications of burnup credit to enhance spent fuel transportation, storage, reprocessing and disposition. Proceedings of a technical meeting

    International Nuclear Information System (INIS)

    2007-05-01

    Given a trend towards higher burnup power reactor fuel, the IAEA began an active programme in burnup credit (BUC) with major meetings in 1997 (IAEA-TECDOC-1013), 2000 (IAEA-TECDOC-1241) and 2002 (IAEA-TECDOC-1378) exploring worldwide interest in using BUC in spent fuel management systems. This publication contains the proceedings of the IAEA's 4th major BUC meeting, held in London. Sixty participants from 18 countries addressed calculation methodology, validation and criticality, safety criteria, procedural compliance with safety criteria, benefits of BUC applications, and regulatory aspects in BUC. This meeting encouraged the IAEA to continue its activities on burnup credit including dissemination of related information, given the number of Member States having to deal with increased spent fuel quantities and extended durations. A 5th major meeting on burnup credit is planned 2008. Burnup credit is a concept that takes credit for the reduced reactivity of fuel discharged from the reactor to improve loading density of irradiated fuel assemblies in storage, transportation, and disposal applications, relative to the assumption of fresh fuel nuclide inventories in loading calculations. This report has described a general four phase approach to be considered in burnup credit implementation. Much if not all of the background research and data acquisition necessary for successful burnup credit development in preparation for licensing has been completed. Many fuel types, facilities, and analysis methods are encompassed in the public knowledge base, such that in many cases this guidance will provide a means for rapid development of a burnup credit program. For newer assembly designs, higher enrichment fuels, and more extensive nuclide credit, additional research and development may be necessary, but even this work can build on the foundation that has been established to date. Those, it is hoped that this report will serve as a starting point with sufficient reference to

  7. Enhanced nutrient transport improves the depth-dependent properties of tri-layered engineered cartilage constructs with zonal co-culture of chondrocytes and MSCs.

    Science.gov (United States)

    Kim, Minwook; Farrell, Megan J; Steinberg, David R; Burdick, Jason A; Mauck, Robert L

    2017-08-01

    Biomimetic design in cartilage tissue engineering is a challenge given the complexity of the native tissue. While numerous studies have generated constructs with near-native bulk properties, recapitulating the depth-dependent features of native tissue remains a challenge. Furthermore, limitations in nutrient transport and matrix accumulation in engineered constructs hinders maturation within the central core of large constructs. To overcome these limitations, we fabricated tri-layered constructs that recapitulate the depth-dependent cellular organization and functional properties of native tissue using zonally derived chondrocytes co-cultured with MSCs. We also introduced porous hollow fibers (HFs) and HFs/cotton threads to enhance nutrient transport. Our results showed that tri-layered constructs with depth-dependent organization and properties could be fabricated. The addition of HFs or HFs/threads improved matrix accumulation in the central core region. With HF/threads, the local modulus in the deep region of tri-layered constructs nearly matched that of native tissue, though the properties in the central regions remained lower. These constructs reproduced the zonal organization and depth-dependent properties of native tissue, and demonstrate that a layer-by-layer fabrication scheme holds promise for the biomimetic repair of focal cartilage defects. Articular cartilage is a highly organized tissue driven by zonal heterogeneity of cells, extracellular matrix proteins and fibril orientations, resulting in depth-dependent mechanical properties. Therefore, the recapitulation of the functional properties of native cartilage in a tissue engineered construct requires such a biomimetic design of the morphological organization, and this has remained a challenge in cartilage tissue engineering. This study demonstrates that a layer-by-layer fabrication scheme, including co-cultures of zone-specific articular CHs and MSCs, can reproduce the depth-dependent characteristics

  8. Dark matter sterile neutrinos in stellar collapse: Alteration of energy/lepton number transport, and a mechanism for supernova explosion enhancement

    Science.gov (United States)

    Hidaka, Jun; Fuller, George M.

    2006-12-01

    We investigate matter-enhanced Mikheyev-Smirnov-Wolfenstein (MSW) active-sterile neutrino conversion in the νe⇌νs channel in the collapse of the iron core of a presupernova star. For values of sterile neutrino rest mass ms and vacuum mixing angle θ (specifically, 0.5keV5×10-12) which include those required for viable sterile neutrino dark matter, our one-zone in-fall phase collapse calculations show a significant reduction in core lepton fraction. This would result in a smaller homologous core and therefore a smaller initial shock energy, disfavoring successful shock reheating and the prospects for an explosion. However, these calculations also suggest that the MSW resonance energy can exhibit a minimum located between the center and surface of the core. In turn, this suggests a post-core-bounce mechanism to enhance neutrino transport and neutrino luminosities at the core surface and thereby augment shock reheating: (1) scattering-induced or coherent MSW νe→νs conversion occurs deep in the core, at the first MSW resonance, where νe energies are large (˜150MeV); (2) the high energy νs stream outward at near light speed; (3) they deposit their energy when they encounter the second MSW resonance νs→νe just below the proto-neutron star surface.

  9. Sol-gel-processed yttrium-doped NiO as hole transport layer in inverted perovskite solar cells for enhanced performance

    Science.gov (United States)

    Hu, Zijun; Chen, Da; Yang, Pan; Yang, Lijun; Qin, Laishun; Huang, Yuexiang; Zhao, Xiaochong

    2018-05-01

    In this work, high-performance inverted planar perovskite solar cells (PSCs) using sol-gel processed Y-doped NiO thin films as hole transport layer (HTL) were demonstrated. Y-doped NiO thin films containing different Y doping concentrations were successfully prepared through a simple sol-gel process. The Y doping could significantly improve the electrical conductivity of NiO thin film, and the photovoltaic performance of Y-doped NiO HTL-based PSC devices outperformed that of the pristine NiO HTL-based device. Notably, the PSC using a 5%Y-NiO HTL exhibited the champion performance with an open-circuit voltage (Voc) of 1.00 V, a short circuit current density (Jsc) of 23.82 mA cm-2, a fill factor (FF) of 68% and a power conversion efficiency (PCE) of 16.31%, resulting in a 27.62% enhancement in PCE in comparison with the NiO device. The enhanced performance of the Y-doped NiO device could be attributed to the improved hole mobility, the high quality compact active layer morphology, the more efficient charge extraction from perovskite absorber as well as the lower recombination probability of charge carriers. Thus, this work provides a simple and effective approach to improve the electrical conductivity of p-type NiO thin films for use as a promising HTL in high performance PSCs.

  10. Low-Magnitude High-Frequency Vibration Accelerated the Foot Wound Healing of n5-streptozotocin-induced Diabetic Rats by Enhancing Glucose Transporter 4 and Blood Microcirculation.

    Science.gov (United States)

    Yu, Caroline Oi-Ling; Leung, Kwok-Sui; Jiang, Jonney Lei; Wang, Tina Bai-Yan; Chow, Simon Kwoon-Ho; Cheung, Wing-Hoi

    2017-09-14

    Delayed wound healing is a Type 2 diabetes mellitus (DM) complication caused by hyperglycemia, systemic inflammation, and decreased blood microcirculation. Skeletal muscles are also affected by hyperglycemia, resulting in reduced blood flow and glucose uptake. Low Magnitude High Frequency Vibration (LMHFV) has been proven to be beneficial to muscle contractility and blood microcirculation. We hypothesized that LMHFV could accelerate the wound healing of n5-streptozotocin (n5-STZ)-induced DM rats by enhancing muscle activity and blood microcirculation. This study investigated the effects of LMHFV in an open foot wound created on the footpad of n5-STZ-induced DM rats (DM_V), compared with no-treatment DM (DM), non-DM vibration (Ctrl_V) and non-DM control rats (Ctrl) on Days 1, 4, 8 and 13. Results showed that the foot wounds of DM_V and Ctrl_V rats were significantly reduced in size compared to DM and Ctrl rats, respectively, at Day 13. The blood glucose level of DM_V rats was significantly reduced, while the glucose transporter 4 (GLUT4) expression and blood microcirculation of DM_V rats were significantly enhanced in comparison to those of DM rats. In conclusion, LMHFV can accelerate the foot wound healing process of n5-STZ rats.

  11. Enhanced thermoelectric transport in modulation-doped GaN/AlGaN core/shell nanowires

    International Nuclear Information System (INIS)

    Song, Erdong; Martinez, Julio A; Li, Qiming; Pan, Wei; Wang, George T; Swartzentruber, Brian

    2016-01-01

    The thermoelectric properties of unintentionally n-doped core GaN/AlGaN core/shell N-face nanowires are reported. We found that the temperature dependence of the electrical conductivity is consistent with thermally activated carriers with two distinctive donor energies. The Seebeck coefficient of GaN/AlGaN nanowires is more than twice as large as that for the GaN nanowires alone. However, an outer layer of GaN deposited onto the GaN/AlGaN core/shell nanowires decreases the Seebeck coefficient at room temperature, while the temperature dependence of the electrical conductivity remains the same. We attribute these observations to the formation of an electron gas channel within the heavily-doped GaN core of the GaN/AlGaN nanowires. The room-temperature thermoelectric power factor for the GaN/AlGaN nanowires can be four times higher than the GaN nanowires. Selective doping in bandgap engineered core/shell nanowires is proposed for enhancing the thermoelectric power. (paper)

  12. Enhanced thermoelectric transport in modulation-doped GaN/AlGaN core/shell nanowires.

    Science.gov (United States)

    Song, Erdong; Li, Qiming; Swartzentruber, Brian; Pan, Wei; Wang, George T; Martinez, Julio A

    2016-01-08

    The thermoelectric properties of unintentionally n-doped core GaN/AlGaN core/shell N-face nanowires are reported. We found that the temperature dependence of the electrical conductivity is consistent with thermally activated carriers with two distinctive donor energies. The Seebeck coefficient of GaN/AlGaN nanowires is more than twice as large as that for the GaN nanowires alone. However, an outer layer of GaN deposited onto the GaN/AlGaN core/shell nanowires decreases the Seebeck coefficient at room temperature, while the temperature dependence of the electrical conductivity remains the same. We attribute these observations to the formation of an electron gas channel within the heavily-doped GaN core of the GaN/AlGaN nanowires. The room-temperature thermoelectric power factor for the GaN/AlGaN nanowires can be four times higher than the GaN nanowires. Selective doping in bandgap engineered core/shell nanowires is proposed for enhancing the thermoelectric power.

  13. Exploitation of sub-micron cavitation nuclei to enhance ultrasound-mediated transdermal transport and penetration of vaccines.

    Science.gov (United States)

    Bhatnagar, Sunali; Kwan, James J; Shah, Apurva R; Coussios, Constantin-C; Carlisle, Robert C

    2016-09-28

    Inertial cavitation mediated by ultrasound has been previously shown to enable skin permeabilisation for transdermal drug and vaccine delivery, by sequentially applying the ultrasound then the therapeutic in liquid form on the skin surface. Using a novel hydrogel dosage form, we demonstrate that the use of sub-micron gas-stabilising polymeric nanoparticles (nanocups) to sustain and promote cavitation activity during simultaneous application of both drug and vaccine results in a significant enhancement of both the dose and penetration of a model vaccine, Ovalbumin (OVA), to depths of 500μm into porcine skin. The nanocups themselves exceeded the penetration depth of the vaccine (up to 700μm) due to their small size and capacity to 'self-propel'. In vivo murine studies indicated that nanocup-assisted ultrasound transdermal vaccination achieved significantly (pultrasound-assisted vaccine delivery in the presence of nanocups demonstrated substantially higher specific anti-OVA IgG antibody levels compared to other transdermal methods. Further optimisation can lead to a viable, safe and non-invasive delivery platform for vaccines with potential use in a primary care setting or personalized self-vaccination at home. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

  14. Shellac Films as a Natural Dielectric Layer for Enhanced Electron Transport in Polymer Field-Effect Transistors.

    Science.gov (United States)

    Baek, Seung Woon; Ha, Jong-Woon; Yoon, Minho; Hwang, Do-Hoon; Lee, Jiyoul

    2018-06-06

    copolymer-based OFETs, and the use of shellac as a dielectric layer facilitates electron transport at the interface with D-A-type copolymer channels.

  15. The effect of modafinil on the rat dopamine transporter and dopamine receptors D1-D3 paralleling cognitive enhancement in the radial arm maze

    Directory of Open Access Journals (Sweden)

    Yasemin eKarabacak

    2015-08-01

    Full Text Available A series of drugs have been reported to increase memory performance modulating the dopaminergic system and herein modafinil was tested for its working memory (WM enhancing properties. Reuptake inhibition of dopamine, serotonin (SERT and norepinephrine (NET by modafinil was tested. 60 male Sprague Dawley rats were divided into six groups (modafinil-treated 1-5-10 mg/kg body weight, trained and untrained and vehicle treated trained and untrained rats; daily injected intraperitoneally for a period of 10 days and tested in a radial arm maze (RAM, a paradigm for testing spatial WM. Hippocampi were taken six hours following the last day of training and complexes containing the unphosphorylated or phosphorylated dopamine transporter (DAT-CC and pDAT-CC and complexes containing the D1-3 dopamine receptor subunits (D1-D3-CC were determined. Modafinil was binding to the DAT but insignificantly to SERT or NET and dopamine reuptake was blocked specifically (IC50=11.11; SERT 1547; NET 182. From day 8 (day 9 for 1 mg/kg body weight modafinil was decreasing WM errors in the RAM significantly and remarkably at all doses tested as compared to the vehicle controls. WMEs were linked to the D2R-CC and the pDAT-CC. pDAT and D1-D3-CC levels were modulated significantly and modafinil was shown to enhance spatial WM in the rat in a well-documented paradigm at all the three doses and dopamine reuptake inhibition with subsequent modulation of D1-3-CC is proposed as a possible mechanism of action.

  16. Enhancement of Photovoltaic Performance by Utilizing Readily Accessible Hole Transporting Layer of Vanadium(V) Oxide Hydrate in a Polymer-Fullerene Blend Solar Cell.

    Science.gov (United States)

    Jiang, Youyu; Xiao, Shengqiang; Xu, Biao; Zhan, Chun; Mai, Liqiang; Lu, Xinhui; You, Wei

    2016-05-11

    Herein, a successful application of V2O5·nH2O film as hole transporting layer (HTL) instead of PSS in polymer solar cells is demonstrated. The V2O5·nH2O layer was spin-coated from V2O5·nH2O sol made from melting-quenching sol-gel method by directly using vanadium oxide powder, which is readily accessible and cost-effective. V2O5·nH2O (n ≈ 1) HTL is found to have comparable work function and smooth surface to that of PSS. For the solar cell containing V2O5·nH2O HTL and the active layer of the blend of a novel polymer donor (PBDSe-DT2PyT) and the acceptor of PC71BM, the PCE was significantly improved to 5.87% with a 30% increase over 4.55% attained with PSS HTL. Incorporation of V2O5·nH2O as HTL in the polymer solar cell was found to enhance the crystallinity of the active layer, electron-blocking at the anode and the light-harvest in the wavelength range of 400-550 nm in the cell. V2O5·nH2O HTL improves the charge generation and collection and suppress the charge recombination within the PBDSe-DT2PyT:PC71BM solar cell, leading to a simultaneous enhancement in Voc, Jsc, and FF. The V2O5·nH2O HTL proposed in this work is envisioned to be of great potential to fabricate highly efficient PSCs with low-cost and massive production.

  17. Engineering of CH 3 NH 3 PbI 3 Perovskite Crystals by Alloying Large Organic Cations for Enhanced Thermal Stability and Transport Properties

    KAUST Repository

    Peng, Wei

    2016-07-28

    The number of studies on organic–inorganic hybrid perovskites has soared in recent years. However, the majority of hybrid perovskites under investigation are based on a limited number of organic cations of suitable sizes, such as methylammonium and formamidinium. These small cations easily fit into the perovskite\\'s three-dimensional (3D) lead halide framework to produce semiconductors with excellent charge transport properties. Until now, larger cations, such as ethylammonium, have been found to form 2D crystals with lead halide. Here we show for the first time that ethylammonium can in fact be incorporated coordinately with methylammonium in the lattice of a 3D perovskite thanks to a balance of opposite lattice distortion strains. This inclusion results in higher crystal symmetry, improved material stability, and markedly enhanced charge carrier lifetime. This crystal engineering strategy of balancing opposite lattice distortion effects vastly increases the number of potential choices of organic cations for 3D perovskites, opening up new degrees of freedom to tailor their optoelectronic and environmental properties.

  18. Efficiency enhancement of tandem organic light-emitting devices by a combined charge generation layer and organic n-type bis(ethylenedithio)-tetrathiafulvalene-doped electron transport layer

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Jin Taek; Kim, Dae Hun; Koh, Eun Im; Kim, Tae Whan

    2014-11-03

    While the operating voltage of the tandem organic light-emitting devices (OLEDs) with both an organic p-type 1,4,5,8,9,11-hexaazatriphenylene hexacarbonitrile charge generation layer and a bis(ethylenedithio)-tetrathiafulvalene (BEDT-TTF)-doped 1,3,5-tris(N-phenylbenzimiazole-2-yl)benzene (TPBi) electron transport layer (ETL) was 1.3 V lower than that of the tandem OLEDs with a BEDT-TTF-undoped TPBi ETL. Luminance efficiency of the tandem OLEDs with a BEDT-TTF-doped TPBi ETL was 3.6 cd/A higher than that of the typical OLEDs. The increase in the luminance efficiency and the decrease in the operating voltage of the tandem OLEDs were attributed to improved electron injection due to the insertion of the BEDT-TTF-doped TPBi ETL. - Highlights: • Tandem organic light-emitting diodes (OLED) were fabricated. • OLED fabricated with an n-type bis(ethylenedithio)-tetrathiafulvalene. • Operating voltage of the tandem OLED was decreased from 19.8 to 18.5 V. • Luminance efficiency of the tandem OLED was increased from 31.8 to 35.4 cd/A. • Enhancement of the luminance efficiency in the tandem OLED was achieved.

  19. Engineering of CH 3 NH 3 PbI 3 Perovskite Crystals by Alloying Large Organic Cations for Enhanced Thermal Stability and Transport Properties

    KAUST Repository

    Peng, Wei; Miao, Xiaohe; Adinolfi, Valerio; Alarousu, Erkki; El Tall, Omar; Emwas, Abdul-Hamid M.; Zhao, Chao; Walters, Grant; Liu, Jiakai; Ouellette, Olivier; Pan, Jun; Banavoth, Murali; Sargent, Edward H.; Mohammed, Omar F.; Bakr, Osman

    2016-01-01

    The number of studies on organic–inorganic hybrid perovskites has soared in recent years. However, the majority of hybrid perovskites under investigation are based on a limited number of organic cations of suitable sizes, such as methylammonium and formamidinium. These small cations easily fit into the perovskite's three-dimensional (3D) lead halide framework to produce semiconductors with excellent charge transport properties. Until now, larger cations, such as ethylammonium, have been found to form 2D crystals with lead halide. Here we show for the first time that ethylammonium can in fact be incorporated coordinately with methylammonium in the lattice of a 3D perovskite thanks to a balance of opposite lattice distortion strains. This inclusion results in higher crystal symmetry, improved material stability, and markedly enhanced charge carrier lifetime. This crystal engineering strategy of balancing opposite lattice distortion effects vastly increases the number of potential choices of organic cations for 3D perovskites, opening up new degrees of freedom to tailor their optoelectronic and environmental properties.

  20. Investigation of enhanced cross-city transport and trapping of air pollutants by coastal and urban land-sea breeze circulations

    Science.gov (United States)

    Lo, Jeff C. F.; Lau, Alexis K. H.; Fung, Jimmy C. H.; Chen, Fei

    2006-07-01

    Recent satellite observations show that a layer of haze perpetually hangs over the Pearl River Delta (PRD) region and surface observations show numerous violations of the Hong Kong Air Quality Objective. This layer of haze mostly concentrates in the Pearl River Estuary and a narrow (20 km wide) band along the shoreline, in particular during weak wind situations. Although researchers suspect the land-sea breeze (LSB) circulations "concentrate" or "trap" various pollutants in this region, the physical mechanism of the phenomenon has never been fully explained or quantified. In this paper, a mesoscale atmospheric model (MM5) coupled with the Noah land surface model (LSM), which has bulk urban land use treatments along with a detailed Pearl River Delta land use map, is used to investigate the unique feature and mechanism of this land-sea breeze effect and the temporal evolution. A three-dimensional particle trajectory model is used to understand its associated pollutant transport, trapping and accumulation. A conceptual model is then developed for the perpetual air pollution phenomenon in the region. Further sensitivity experiments are used to illustrate the impact of urbanization and large-scale winds on the pollution processes. Results show that urbanization enhances the pollutant trapping and therefore contributes to the overall poor air quality in the region.

  1. Efficiency enhancement of tandem organic light-emitting devices by a combined charge generation layer and organic n-type bis(ethylenedithio)-tetrathiafulvalene-doped electron transport layer

    International Nuclear Information System (INIS)

    Cho, Jin Taek; Kim, Dae Hun; Koh, Eun Im; Kim, Tae Whan

    2014-01-01

    While the operating voltage of the tandem organic light-emitting devices (OLEDs) with both an organic p-type 1,4,5,8,9,11-hexaazatriphenylene hexacarbonitrile charge generation layer and a bis(ethylenedithio)-tetrathiafulvalene (BEDT-TTF)-doped 1,3,5-tris(N-phenylbenzimiazole-2-yl)benzene (TPBi) electron transport layer (ETL) was 1.3 V lower than that of the tandem OLEDs with a BEDT-TTF-undoped TPBi ETL. Luminance efficiency of the tandem OLEDs with a BEDT-TTF-doped TPBi ETL was 3.6 cd/A higher than that of the typical OLEDs. The increase in the luminance efficiency and the decrease in the operating voltage of the tandem OLEDs were attributed to improved electron injection due to the insertion of the BEDT-TTF-doped TPBi ETL. - Highlights: • Tandem organic light-emitting diodes (OLED) were fabricated. • OLED fabricated with an n-type bis(ethylenedithio)-tetrathiafulvalene. • Operating voltage of the tandem OLED was decreased from 19.8 to 18.5 V. • Luminance efficiency of the tandem OLED was increased from 31.8 to 35.4 cd/A. • Enhancement of the luminance efficiency in the tandem OLED was achieved

  2. Enhancing the connectivity of high speed rail in the Orlando-Tampa corridor with local public transportation systems : issues and opportunities.

    Science.gov (United States)

    2011-01-01

    High Speed Rail (HSR) will only be truly transformational if it has effective connections with as many other modes of transportation as possible. This project looks at local public transportation systems that have opportunities to connect to HSR stat...

  3. Surface transportation security : TSA has taken actions to manage risk, improve coordination, and measure performance, but additional actions would enhance its efforts, April 21, 2010.

    Science.gov (United States)

    2010-04-21

    Terrorist attacks on surface transportation facilities in Moscow, Mumbai, London, and Madrid caused casualties and highlighted the vulnerability of such systems. The Transportation Security Administration (TSA), within the Department of Homeland Secu...

  4. Water-transporting proteins

    DEFF Research Database (Denmark)

    Zeuthen, Thomas

    2010-01-01

    . In the K(+)/Cl(-) and the Na(+)/K(+)/2Cl(-) cotransporters, water is entirely cotransported, while water transport in glucose uniporters and Na(+)-coupled transporters of nutrients and neurotransmitters takes place by both osmosis and cotransport. The molecular mechanism behind cotransport of water...... transport. Epithelial water transport is energized by the movements of ions, but how the coupling takes place is uncertain. All epithelia can transport water uphill against an osmotic gradient, which is hard to explain by simple osmosis. Furthermore, genetic removal of aquaporins has not given support...... to osmosis as the exclusive mode of transport. Water cotransport can explain the coupling between ion and water transport, a major fraction of transepithelial water transport and uphill water transport. Aquaporins enhance water transport by utilizing osmotic gradients and cause the osmolarity...

  5. Aerosol optical characteristics and their vertical distributions under enhanced haze pollution events: effect of the regional transport of different aerosol types over eastern China

    Science.gov (United States)

    Sun, Tianze; Che, Huizheng; Qi, Bing; Wang, Yaqiang; Dong, Yunsheng; Xia, Xiangao; Wang, Hong; Gui, Ke; Zheng, Yu; Zhao, Hujia; Ma, Qianli; Du, Rongguang; Zhang, Xiaoye

    2018-03-01

    The climatological variation of aerosol properties and the planetary boundary layer (PBL) during 2013-2015 over the Yangtze River Delta (YRD) region were investigated by employing ground-based Micro Pulse Lidar (MPL) and CE-318 sun-photometer observations. Combining Moderate Resolution Imaging Spectroradiometer (MODIS) and Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) satellite products, enhanced haze pollution events affected by different types of aerosol over the YRD region were analyzed through vertical structures, spatial distributions, backward trajectories, and the potential source contribution function (PSCF) model. The results show that aerosols in the YRD are dominated by fine-mode particles, except in March. The aerosol optical depth (AOD) in June and September is higher due to high single scattering albedo (SSA) from hygroscopic growth, but it is lower in July and August due to wet deposition from precipitation. The PBL height (PBLH) is greater (means ranging from 1.23 to 1.84 km) and more variable in the warmer months of March to August, due to the stronger diurnal cycle and exchange of heat. Northern fine-mode pollutants are brought to the YRD at a height of 1.5 km. The SSA increases, blocking the radiation to the surface, and cooling the surface, thereby weakening turbulence, lowering the PBL, and in turn accelerating the accumulation of pollutants, creating a feedback to the cooling effect. Originated from the deserts in Xinjiang and Inner Mongolia, long-range transported dust masses are seen at heights of about 2 km over the YRD region with an SSA440 nm below 0.84, which heat air and raise the PBL, accelerating the diffusion of dust particles. Regional transport from biomass-burning spots to the south of the YRD region bring mixed aerosol particles at a height below 1.5 km, resulting in an SSA440 nm below 0.89. During the winter, the accumulation of the local emission layer is facilitated by stable weather conditions

  6. Aerosol optical characteristics and their vertical distributions under enhanced haze pollution events: effect of the regional transport of different aerosol types over eastern China

    Directory of Open Access Journals (Sweden)

    T. Sun

    2018-03-01

    Full Text Available The climatological variation of aerosol properties and the planetary boundary layer (PBL during 2013–2015 over the Yangtze River Delta (YRD region were investigated by employing ground-based Micro Pulse Lidar (MPL and CE-318 sun-photometer observations. Combining Moderate Resolution Imaging Spectroradiometer (MODIS and Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO satellite products, enhanced haze pollution events affected by different types of aerosol over the YRD region were analyzed through vertical structures, spatial distributions, backward trajectories, and the potential source contribution function (PSCF model. The results show that aerosols in the YRD are dominated by fine-mode particles, except in March. The aerosol optical depth (AOD in June and September is higher due to high single scattering albedo (SSA from hygroscopic growth, but it is lower in July and August due to wet deposition from precipitation. The PBL height (PBLH is greater (means ranging from 1.23 to 1.84 km and more variable in the warmer months of March to August, due to the stronger diurnal cycle and exchange of heat. Northern fine-mode pollutants are brought to the YRD at a height of 1.5 km. The SSA increases, blocking the radiation to the surface, and cooling the surface, thereby weakening turbulence, lowering the PBL, and in turn accelerating the accumulation of pollutants, creating a feedback to the cooling effect. Originated from the deserts in Xinjiang and Inner Mongolia, long-range transported dust masses are seen at heights of about 2 km over the YRD region with an SSA440 nm below 0.84, which heat air and raise the PBL, accelerating the diffusion of dust particles. Regional transport from biomass-burning spots to the south of the YRD region bring mixed aerosol particles at a height below 1.5 km, resulting in an SSA440 nm below 0.89. During the winter, the accumulation of the local emission layer is facilitated by

  7. Combining water-rock interaction experiments with reaction path and reactive transport modelling to predict reservoir rock evolution in an enhanced geothermal system

    Science.gov (United States)

    Kuesters, Tim; Mueller, Thomas; Renner, Joerg

    2016-04-01

    Reliably predicting the evolution of mechanical and chemical properties of reservoir rocks is crucial for efficient exploitation of enhanced geothermal systems (EGS). For example, dissolution and precipitation of individual rock forming minerals often result in significant volume changes, affecting the hydraulic rock properties and chemical composition of fluid and solid phases. Reactive transport models are typically used to evaluate and predict the effect of the internal feedback of these processes. However, a quantitative evaluation of chemo-mechanical interaction in polycrystalline environments is elusive due to poorly constrained kinetic data of complex mineral reactions. In addition, experimentally derived reaction rates are generally faster than reaction rates determined from natural systems, likely a consequence of the experimental design: a) determining the rate of a single process only, e.g. the dissolution of a mineral, and b) using powdered sample materials and thus providing an unrealistically high reaction surface and at the same time eliminating the restrictions on element transport faced in-situ for fairly dense rocks. In reality, multiple reactions are coupled during the alteration of a polymineralic rocks in the presence of a fluid and the rate determining process of the overall reactions is often difficult to identify. We present results of bulk rock-water interaction experiments quantifying alteration reactions between pure water and a granodiorite sample. The rock sample was chosen for its homogenous texture, small and uniform grain size (˜0.5 mm in diameter), and absence of pre-existing alteration features. The primary minerals are plagioclase (plg - 58 vol.%), quartz (qtz - 21 vol.%), K-feldspar (Kfs - 17 vol.%), biotite (bio - 3 vol.%) and white mica (wm - 1 vol.%). Three sets of batch experiments were conducted at 200 ° C to evaluate the effect of reactive surface area and different fluid path ways using (I) powders of the bulk rock with

  8. Enhanced photovoltaic performance of inverted hybrid bulk-heterojunction solar cells using TiO2/reduced graphene oxide films as electron transport layers

    Science.gov (United States)

    Morais, Andreia; Alves, João Paulo C.; Lima, Francisco Anderson S.; Lira-Cantu, Monica; Nogueira, Ana Flavia

    2015-01-01

    In this study, we investigated inverted hybrid bulk-heterojunction solar cells with the following configuration: fluorine-doped tin oxide (FTO) |TiO2/RGO|P3HT:PC61BM|V2O5 or PEDOT:PSS|Ag. The TiO2/GO dispersions were prepared by sol-gel method, employing titanium isopropoxide and graphene oxide (GO) as starting materials. The GO concentration was varied from 0.1 to 4.0 wt%. The corresponding dispersions were spin-coated onto FTO substrates and a thermal treatment was performed to remove organic materials and to reduce GO to reduced graphene oxide (RGO). The TiO2/RGO films were characterized by x-ray diffraction, Raman spectroscopy, and microscopy techniques. Atomic force microscopy (AFM) images showed that the addition of RGO significantly changes the morphology of the TiO2 films, with loss of uniformity and increase in surface roughness. Independent of the use of V2O5 or PEDOT: PSS films as the hole transport layer, the incorporation of 2.0 wt% of RGO into TiO2 films was the optimal concentration for the best organic photovoltaic performance. The solar cells based on TiO2/RGO (2.0 wt%) electrode exhibited a ˜22.3% and ˜28.9% short circuit current density (Jsc) and a power conversion efficiency enhancement, respectively, if compared with the devices based on pure TiO2 films. Kelvin probe force microscopy images suggest that the incorporation of RGO into TiO2 films can promote the appearance of regions with different charge dissipation capacities.

  9. Mesoporous anatase TiO_2 microspheres with interconnected nanoparticles delivering enhanced dye-loading and charge transport for efficient dye-sensitized solar cells

    International Nuclear Information System (INIS)

    Chu, Liang; Qin, Zhengfei; Zhang, Qiaoxia; Chen, Wei; Yang, Jian; Yang, Jianping; Li, Xing’ao

    2016-01-01

    Graphical abstract: The photoelectrodes of DSSCs consisted of mesoporous anatase TiO_2 microspheres with interconnected nanoparticles. The interconnected nanoparticles enhance dye-loading capacity and charge transport. - Highlights: • The mesoporous anatase TiO_2 microspheres were synthesized by a template-free, one-step fast solvothermal process. • The mesoporous anatase TiO_2 microspheres with interconnected nanoparticles have the advantages of large surface area and connected-structure for electron transfer. • The mesoporous anatase TiO_2 microspheres were further utilized as efficient photoelectrodes for dye-sensitized solar cells. - Abstract: Mesoporous anatase TiO_2 microspheres with interconnected nanostructures meet both large surface area and connected-structure for electron transfer as ideal nano/micromaterials for application in solar cells, energy storage, catalysis, water splitting and gas sensing. In this work, mesoporous anatase TiO_2 microspheres consisting of interconnected nanoparticles were synthesized by template-free, one-step fast solvothermal process, where urea was used as capping agent to control phase and promote oriented growth. The morphology was assembled by nucleation-growth-assembly-mechanism. The mesoporous anatase TiO_2 microspheres with interconnected nanoparticles were further utilized as efficient photoelectrodes of dye-sensitized solar cells (DSSCs), which were beneficial to capacity of dye loading and charge transfer. The power conversion efficiency (PCE) based on the optimized thickness of TiO_2 photoelectrodes was up to 7.13% under standard AM 1.5 G illumination (100 mW/cm"2).

  10. Quantum transport in nanowire-based hybrid devices

    Energy Technology Data Exchange (ETDEWEB)

    Guenel, Haci Yusuf

    2013-05-08

    We have studied the low-temperature transport properties of nanowires contacted by a normal metal as well as by superconducting electrodes. As a consequence of quantum coherence, we have demonstrated the electron interference effect in different aspects. The mesoscopic phase coherent transport properties were studied by contacting the semiconductor InAs and InSb nanowires with normal metal electrodes. Moreover, we explored the interaction of the microscopic quantum coherence of the nanowires with the macroscopic quantum coherence of the superconductors. In superconducting Nb contacted InAs nanowire junctions, we have investigated the effect of temperature, magnetic field and electric field on the supercurrent. Owing to relatively high critical temperature of superconducting Nb (T{sub c} ∝ 9 K), we have observed the supercurrent up to 4 K for highly doped nanowire-based junctions, while for low doped nanowire-based junctions a full control of the supercurrent was achieved. Due to low transversal dimension of the nanowires, we have found a monotonous decay of the critical current in magnetic field dependent measurements. The experimental results were analyzed within narrow junction model which has been developed recently. At high bias voltages, we have observed subharmonic energy gap structures as a consequence of multiple Andreev reflection. Some of the nanowires were etched, such that the superconducting Nb electrodes are connected to both ends of the nanowire rather than covering the surface of the nanowire. As a result of well defined nanowire-superconductor interfaces, we have examined quasiparticle interference effect in magnetotransport measurements. Furthermore, we have developed a new junction geometry, such that one of the superconducting Nb electrodes is replaced by a superconducting Al. Owing to the smaller critical magnetic field of superconducting Al (B{sub c} ∝ 15-50,mT), compared to superconducting Nb (B{sub c} ∝ 3 T), we were able to studied

  11. Coherent Charge Transport in Ballistic InSb Nanowire Josephson Junctions

    Science.gov (United States)

    Li, S.; Kang, N.; Fan, D. X.; Wang, L. B.; Huang, Y. Q.; Caroff, P.; Xu, H. Q.

    2016-01-01

    Hybrid InSb nanowire-superconductor devices are promising for investigating Majorana modes and topological quantum computation in solid-state devices. An experimental realisation of ballistic, phase-coherent superconductor-nanowire hybrid devices is a necessary step towards engineering topological superconducting electronics. Here, we report on a low-temperature transport study of Josephson junction devices fabricated from InSb nanowires grown by molecular-beam epitaxy and provide a clear evidence for phase-coherent, ballistic charge transport through the nanowires in the junctions. We demonstrate that our devices show gate-tunable proximity-induced supercurrent and clear signatures of multiple Andreev reflections in the differential conductance, indicating phase-coherent transport within the junctions. We also observe periodic modulations of the critical current that can be associated with the Fabry-Pérot interference in the nanowires in the ballistic transport regime. Our work shows that the InSb nanowires grown by molecular-beam epitaxy are of excellent material quality and hybrid superconducting devices made from these nanowires are highly desirable for investigation of the novel physics in topological states of matter and for applications in topological quantum electronics. PMID:27102689

  12. Modelling the impact of cyber attacks on the traffic control centre of an urban automobile transport system by means of enhanced cybersecurity

    Directory of Open Access Journals (Sweden)

    Ivanova Yoana

    2017-01-01

    Full Text Available This paper aims to show the major role means of protection play for strengthening the cybersecurity of critical transport infrastructure by using the advanced method of simulation modelling. The simulation model of a Traffic Control Centre (TTC of an urban Automobile Transport System (ATS is created by the author in the Riverbed Modeler Academic Edition 17.5 computer networks simulation system and is exposed to the impact of a Denial-of-Service attack. In addition, logical conclusions have been made on the basis of the experimental results obtained and evaluated by comparative analysis with results from analogous previous studies.

  13. Pulsed laser-assisted focused electron-beam-induced etching of titanium with XeF2: enhanced reaction rate and precursor transport.

    Science.gov (United States)

    Noh, J H; Fowlkes, J D; Timilsina, R; Stanford, M G; Lewis, B B; Rack, P D

    2015-02-25

    In order to enhance the etch rate of electron-beam-induced etching, we introduce a laser-assisted focused electron-beam-induced etching (LA-FEBIE) process which is a versatile, direct write nanofabrication method that allows nanoscale patterning and editing. The results demonstrate that the titanium electron stimulated etch rate via the XeF2 precursor can be enhanced up to a factor of 6 times with an intermittent pulsed laser assist. The evolution of the etching process is correlated to in situ stage current measurements and scanning electron micrographs as a function of time. The increased etch rate is attributed to photothermally enhanced Ti-F reaction and TiF4 desorption and in some regimes enhanced XeF2 surface diffusion to the reaction zone.

  14. Intelligent Freigth Transport Systems

    DEFF Research Database (Denmark)

    Overø, Helene Martine; Larsen, Allan; Røpke, Stefan

    2009-01-01

    is to enhance the efficiency and lower the environmental impact in freight transport. In this paper, a pilot project involving real-time waste collection at a Danish waste collection company is described, and a solution approach is proposed. The problem corresponds to the dynamic version of the waste collection......The Danish innovation project entitled “Intelligent Freight Transport Systems” aims at developing prototype systems integrating public intelligent transport systems (ITS) with the technology in vehicles and equipment as well as the IT-systems at various transport companies. The objective...

  15. Remote Loading of 64Cu2+ into Liposomes without the Use of Ion Transport Enhancers

    DEFF Research Database (Denmark)

    Henriksen, Jonas Rosager; Petersen, Anncatrine Luisa; Hansen, Anders Elias

    2015-01-01

    Due to low ion permeability of lipid bilayers, it has been and still is common practice to use transporter molecules such as ionophores or lipophilic chelators to increase transmembrane diffusion rates and loading efficiencies of radionuclides into liposomes. Here, we report a novel and very simple...

  16. Sodium-bicarbonate cotransporter NBCn1 in the kidney medullary thick ascending limb cell line is upregulated under acidic conditions and enhances ammonium transport.

    Science.gov (United States)

    Lee, Soojung; Lee, Hye Jeong; Yang, Han Soo; Thornell, Ian M; Bevensee, Mark O; Choi, Inyeong

    2010-09-01

    In this study, we examined the effect of bicarbonate transporters on ammonium/ammonia uptake in the medullary thick ascending limb cell line ST-1. Cells were treated with 1 mm ouabain and 0.2 mM bumetanide to minimize carrier-mediated NH(4)(+) transport, and the intracellular accumulation of (14)C-methylammonium/methylammonia ((14)C-MA) was determined. In CO(2)/HCO(3)(-)-free solution, cells at normal pH briefly accumulated (14)C-MA over 7 min and reached a plateau. In CO(2)/HCO(3)(-) solution, however, cells markedly accumulated (14)C-MA over the experimental period of 30 min. This CO(2)/HCO(3)(-)-dependent accumulation was reduced by the bicarbonate transporter blocker, 4,4-diisothiocyanatostilbene-2,2-disulfonate (DIDS; 0.5 mM). Replacing Cl(-) with gluconate reduced the accumulation, but the reduction was more substantial in the presence of DIDS. Incubation of cells at pH 6.8 (adjusted with NaHCO(3) in 5% CO(2)) for 24 h lowered the mean steady-state intracellular pH to 6.96, significantly lower than 7.28 for control cells. The presence of DIDS reduced (14)C-MA accumulation in control conditions but had no effect after acidic incubation. Immunoblotting showed that NBCn1 was upregulated after acidic incubation and in NH(4)Cl-containing media. The Cl(-)-HCO(3)(-) exchanger AE2 was present, but its expression remained unaffected by acidic incubation. Expressed in Xenopus oocytes, NBCn1 increased carrier-mediated (14)C-MA transport, which was abolished by replacing Na(+). Two-electrode voltage clamp of oocytes exhibited negligible current after NH(4)Cl application. These results suggest that DIDS-sensitive HCO(3)(-) extrusion normally governs NH(4)(+)/NH(3) uptake in the medullary thick ascending limb cells. We propose that, in acidic conditions, DIDS-sensitive HCO(3)(-) extrusion is inactivated, while NBCn1 is upregulated to stimulate NH(4)(+) transport.

  17. New airborne pathogen transport model for upper-room UVGI spaces conditioned by chilled ceiling and mixed displacement ventilation: Enhancing air quality and energy performance

    International Nuclear Information System (INIS)

    Kanaan, Mohamad; Ghaddar, Nesreen; Ghali, Kamel; Araj, Georges

    2014-01-01

    Highlights: • A model of bacteria transport is developed in CC/DV conditioned spaces with UVGI. • The model identifies buoyant, partially mixed, and fully mixed transport zones. • The predicted bacteria concentration agreed well with CFD results. • The higher the supply flow rate, the more restrictive is return air mixing ratio. • Upper-room UVGI results in higher return mixing and 33% in energy savings. - Abstract: The maximum allowable return air ratio in chilled ceiling (CC) and mixed displacement ventilation (DV) system for good air quality is regulated by acceptable levels of CO 2 concentration not to exceed 700 ppm and airborne bacterial count to satisfy World Health Organization (WHO) requirement for bacterial count not to exceed 500 CFU/m 3 . Since the CC/DV system relies on buoyancy effects for driving the contaminated air upwards, infectious particles will recirculate in the upper zone allowing effective utilization of upper-room ultraviolet germicidal irradiation (UVGI) to clean return air. The aim of this work is to develop a new airborne bacteria transport plume-multi-layer zonal model at low computational cost to predict bacteria concentration distribution in mixed CC/DV conditioned room without and with upper-room UVGI installed. The results of the simplified model were compared with layer-averaged concentration predictions of a detailed and experimentally-validated 3-D computational fluid dynamics (CFD) model. The comparison showed good agreement between bacteria transport model results and CFD predictions of room air bacteria concentration with maximum error of ±10.4 CFU/m 3 in exhaust air. The simplified model captured the vertical bacteria concentration distribution in room air as well as the locking effect of highest concentration happening at the stratification level. The developed bacteria transport model was used in a case study to determine the return air mixing ratio that minimizes energy consumption and maintains acceptable IAQ

  18. Quantum Dots and Andreev Reflections in Graphene

    NARCIS (Netherlands)

    Liu, X.L.

    2010-01-01

    Graphene is an exceptionally thin semiconductor that consists of only one atomic layer of carbon atoms. The electrons in graphene live in a strictly two-dimensional (2D) world. In addition to this remarkable 2Dness, it is also peculiar that the behavior of the electrons in graphene is governed by

  19. Defense Programs Transportation Risk Assessment

    International Nuclear Information System (INIS)

    Clauss, D.B.

    1994-01-01

    This paper provides an overview of the methodology used in a probabilistic transportation risk assessment conducted to assess the probabilities and consequences of inadvertent dispersal of radioactive materials arising from severe transportation accidents. The model was developed for the Defense Program Transportation Risk Assessment (DPTRA) study. The analysis incorporates several enhancements relative to previous risk assessments of hazardous materials transportation including newly-developed statistics on the frequencies and severities of tractor semitrailer accidents and detailed route characterization using the 1990 Census data

  20. Modelling of transport phenomena

    International Nuclear Information System (INIS)

    Itoh, Kimitaka; Itoh, Sanae; Fukuyama, Atsushi.

    1993-09-01

    In this review article, we discuss key features of the transport phenomena and theoretical modelling to understand them. Experimental observations have revealed the nature of anomalous transport, i.e., the enhancement of the transport coefficients by the gradients of the plasma profiles, the pinch phenomena, the radial profile of the anomalous transport coefficients, the variation of the transport among the Bohm diffusion, Pseudo-classical confinement, L-mode and variety of improved confinement modes, and the sudden jumps such as L-H transition. Starting from the formalism of the transport matrix, the modelling based on the low frequency instabilities are reviewed. Theoretical results in the range of drift wave frequency are examined. Problems in theories based on the quasilinear and mixing-length estimates lead to the renewal of the turbulence theory, and the physics picture of the self-sustained turbulence is discussed. The theory of transport using the fluid equation of plasma is developed, showing that the new approach is very promising in explaining abovementioned characteristics of anomalous transport in both L-mode and improved confinement plasmas. The interference of the fluxes is the key to construct the physics basis of the bifurcation theory for the L-H transition. The present status of theories on the mechanisms of improved confinement is discussed. Modelling on the nonlocal nature of transport is briefly discussed. Finally, the impact of the anomalous transport on disruptive phenomena is also described. (author) 95 refs

  1. Enhanced glycosylation of factor VIII:C in capillary endothelial cells following β-adrenoreceptor stimulation is not due to increased sugar transport

    International Nuclear Information System (INIS)

    Tavarez-Pagan, J.J.; Oliveira, C.M.; Banerjee, D.K.

    1990-01-01

    Factor VIII:C (Antihemophilia Factor A) in capillary endothelial cells from bovine adrenal medulla found to contain M r 200,000 and M r 46,000 dalton protein species when analyzed by SDS-PAGE under reduced condition. But the secretory FVIII:C under non-reduced condition gave rise to a protein of M r 270,000 dalton indicating that the heavy and light chains are held together by S-S bridge. Upon stimulation of these cells with β-agonist, isoproterenol (10 -7 M), a 2-fold increase in the ratio of [ 3 H]-mannose to [ 35 S]-methionine incorporation in immunoprecipitated FVIII:C was observed. In order to understand the molecular mechanism of this increase, a detail study of sugar transport was carried out. The transport of 2-deoxy-D-[ 3 H]-glucose in these cells was time and temperature dependent. Furthermore, inhibition of 2-deoxy-D-[ 3 H]-glucose uptake by cytochalasin B strongly supported for a carrier mediated process. However, when the transport studies were conducted in the presence of isoproterenol at 10 -5 M or 10 -7 M or 8 Br-cAMP (2 mM) no increase was observed. The kinetic studies indicated that the K m and V max for 2 deoxy-D-[ 3 H]-glucose were 0.24 mM and 0.88 nmol/mg protein/minute, respectively under normal conditions but these values were changed to 0.37 mM and 0.69 nmol/mg protein/minute when stimulated with isoproterenol (10 -7 M)

  2. Enhancement of charge transport properties of small molecule semiconductors by controlling fluorine substitution and effects on photovoltaic properties of organic solar cells and perovskite solar cells.

    Science.gov (United States)

    Yun, Jae Hoon; Park, Sungmin; Heo, Jin Hyuck; Lee, Hyo-Sang; Yoon, Seongwon; Kang, Jinback; Im, Sang Hyuk; Kim, Hyunjung; Lee, Wonmok; Kim, BongSoo; Ko, Min Jae; Chung, Dae Sung; Son, Hae Jung

    2016-11-01

    We prepared a series of small molecules based on 7,7'-(4,4-bis(2-ethylhexyl)-4 H -silolo[3,2- b :4,5- b ']dithiophene-2,6-diyl)bis(4-(5'-hexyl-[2,2'-bithiophene]-5-yl)benzo[ c ][1,2,5]thiadiazole) with different fluorine substitution patterns ( 0F-4F ). Depending on symmetricity and numbers of fluorine atoms incorporated in the benzo[ c ][1,2,5]thiadiazole unit, they show very different optical and morphological properties in a film. 2F and 4F , which featured symmetric and even-numbered fluorine substitution patterns, display improved molecular packing structures and higher crystalline properties in a film compared with 1F and 3F and thus, 2F achieved the highest OTFT mobility, which is followed by 4F . In the bulk heterojunction solar cell fabricated with PC 71 BM, 2F achieves the highest photovoltaic performance with an 8.14% efficiency and 0F shows the lowest efficiency of 1.28%. Moreover, the planar-type perovskite solar cell (PSC) prepared with 2F as a dopant-free hole transport material shows a high power conversion efficiency of 14.5% due to its high charge transporting properties, which were significantly improved compared with the corresponding PSC device obtained from 0F (8.5%). From the studies, it is demonstrated that low variation in the local dipole moment and the narrow distribution of 2F conformers make intermolecular interactions favorable, which may effectively drive crystal formations in the solid state and thus, higher charge transport properties compared with 1F and 3F .

  3. Radiation Transport

    Energy Technology Data Exchange (ETDEWEB)

    Urbatsch, Todd James [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-06-15

    We present an overview of radiation transport, covering terminology, blackbody raditation, opacities, Boltzmann transport theory, approximations to the transport equation. Next we introduce several transport methods. We present a section on Caseology, observing transport boundary layers. We briefly broach topics of software development, including verification and validation, and we close with a section on high energy-density experiments that highlight and support radiation transport.

  4. 3,4-Methylenedioxypyrovalerone prevents while methylone enhances methamphetamine-induced damage to dopamine nerve endings: β-ketoamphetamine modulation of neurotoxicity by the dopamine transporter

    Science.gov (United States)

    Anneken, John H.; Angoa-Pérez, Mariana; Kuhn, Donald M.

    2016-01-01

    Methylone, 3,4-methylenedioxypyrovalerone (MDPV), and mephedrone are psychoactive ingredients of ‘bath salts’ and their abuse represents a growing public health care concern. These drugs are cathinone derivatives and are classified chemically as β-ketoamphetamines. Because of their close structural similarity to the amphetamines, methylone, MDPV, and mephedrone share most of their pharmacological, neurochemical, and behavioral properties. One point of divergence in their actions is the ability to cause damage to the CNS. Unlike methamphetamine, the β-ketoamphetamines do not damage dopamine (DA) nerve endings. However, mephedrone has been shown to significantly accentuate methamphetamine neurotoxicity. Bath salt formulations contain numerous different psychoactive ingredients, and individuals who abuse bath salts also coabuse other illicit drugs. Therefore, we have evaluated the effects of methylone, MDPV, mephedrone, and methamphetamine on DA nerve endings. The β-ketoamphetamines alone or in all possible two-drug combinations do not result in damage to DA nerve endings but do cause hyperthermia. MDPV completely protects against the neurotoxic effects of methamphetamine while methylone accentuates it. Neither MDPV nor methylone attenuates the hyperthermic effects of methamphetamine. The potent neuroprotective effects of MDPV extend to amphetamine-, 3,4-methylenedioxymethamphetamine-, and MPTP-induced neurotoxicity. These results indicate that β-ketoamphetamine drugs that are non-substrate blockers of the DA transporter (i.e., MDPV) protect against methamphetamine neurotoxicity, whereas those that are substrates for uptake by the DA transporter and which cause DA release (i.e., methylone, mephedrone) accentuate neurotoxicity. PMID:25626880

  5. Enhanced efficiency and air-stability of NiOX-based perovskite solar cells via PCBM electron transport layer modification with Triton X-100.

    Science.gov (United States)

    Lee, Kisu; Ryu, Jaehoon; Yu, Haejun; Yun, Juyoung; Lee, Jungsup; Jang, Jyongsik

    2017-11-02

    We modified phenyl-C61-butyric acid methyl ester (PCBM) for use as a stable, efficient electron transport layer (ETL) in inverted perovskite solar cells (PSCs). PCBM containing a surfactant Triton X-100 acts as the ETL and NiO X nanocrystals act as a hole transport layer (HTL). Atomic force microscopy and scanning electron microscopy images showed that surfactant-modified PCBM (s-PCBM) forms a high-quality, uniform, and dense ETL on the rough perovskite layer. This layer effectively blocks holes and reduces interfacial recombination. Steady-state photoluminescence and electrochemical impedance spectroscopy analyses confirmed that Triton X-100 improved the electron extraction performance of PCBM. When the s-PCBM ETL was used, the average power conversion efficiency increased from 10.76% to 15.68%. This improvement was primarily caused by the increases in the open-circuit voltage and fill factor. s-PCBM-based PSCs also showed good air-stability, retaining 83.8% of their initial performance after 800 h under ambient conditions.

  6. Transport de paires EPR dans des structures mesoscopiques

    Science.gov (United States)

    Dupont, Emilie

    Dans cette these, nous nous sommes particulierement interesses a la propagation de paires EPR1 delocalisees et localisees, et a l'influence d'un supraconducteur sur le transport de ces paires. Apres une introduction de cette etude, ainsi que du cadre scientifique qu'est l'informatique quantique dans lequel elle s'inscrit, nous allons dans le chapitre 1 faire un rappel sur le systeme constitue de deux points quantiques normaux entoures de deux fils supraconducteurs. Cela nous permettra d'introduire une methode de calcul qui sera reutilisee par la suite, et de trouver egalement le courant Josephson produit par ce systeme transforme en SQUID-dc par l'ajout d'une jonction auxiliaire. Le SQUID permet de mesurer l'etat de spin (singulet ou triplet), et peut etre forme a partir d'autres systemes que nous etudierons ensuite. Dans le chapitre 2, nous rappellerons l'etude detaillee d'un intricateur d'Andreev faite par un groupe de Bale. La matrice T, permettant d'obtenir le courant dans les cas ou les electrons sont separes spatialement ou non, sera etudiee en detail afin d'en faire usage au chapitre suivant. Le chapitre 3 est consacre a l'etude de l'influence du bruit sur le fonctionnement de l'intricateur d'Andreev. Ce bruit modifie la forme du courant jusqu'a aboutir a d'autres conditions de fonctionnement de l'intricateur. En effet, le bruit present sur les points quantiques peut perturber le transport des paires EPR par l'intermediaire des degres de liberte. Nous montrerons que, du fait de l'"intrication" entre la charge de la paire et le bruit, la paire est detruite pour des temps longs. Cependant, le resultat le plus important sera que le bruit perturbe plus le transport des paires delocalisees, qui implique une resonance de Breit-Wigner a deux particules. Le transport parasite n'implique pour sa part qu'une resonance de Breit-Wigner a une particule. Dans le chapitre 4, nous reviendrons au systeme constitue de deux points quantiques entoures de deux fils

  7. Enhancement in transport critical current density of ex situ PIT Ag/(Ba, K)Fe2As2 tapes achieved by applying a combined process of flat rolling and uniaxial pressing

    Science.gov (United States)

    Togano, Kazumasa; Gao, Zhaoshun; Matsumoto, Akiyoshi; Kumakura, Hiroaki

    2013-11-01

    We report that the transport critical current density Jc of ex situ powder-in-tube (PIT) processed (Ba, K)Fe2As2 (Ba-122) tapes can be significantly enhanced by applying uniaxial cold pressing at the final stage of deformation. The tapes were prepared by packing high quality precursor powder into a Ag tube, cycles of rolling and intermediate annealing, and pressing followed by the final heat treatment for sintering. The Jc values in applied magnetic fields were increased by almost one order of magnitude compared to the tapes processed without pressing, exceeding 104 A cm-2 at 4.2 K. We achieved the highest Jc (at 4.2 K and 10 T) of 2.1×104 A cm-2 among PIT-processed Fe-based wires and tapes reported so far. The Jc-H curves measured at higher temperatures maintain small field dependence up to around 20 K, suggesting that these tapes are promising for applications at higher temperatures as well as at liquid helium temperature. The microstructure investigations reveal that there are two possible causes of the large Jc enhancement by pressing: one is densification and the other is the change of crack structure. Optimization of processing parameters such as the reduction ratio of rolling and pressing is expected to yield further Jc enhancement.

  8. Transport Properties of an Electron-Hole Bilayer in Contact with a Superconductor Hybrid Junction

    Science.gov (United States)

    Bercioux, D.; Klapwijk, T. M.; Bergeret, F. S.

    2017-08-01

    We investigate the transport properties of a junction consisting of an electron-hole bilayer in contact with normal and superconducting leads. The electron-hole bilayer is considered as a semimetal with two electronic bands. We assume that in the region between the contacts the system hosts an exciton condensate described by a BCS-like model with a gap Γ in the quasiparticle density of states. We first discuss how the subgap electronic transport through the junction is mainly governed by the interplay between two kinds of reflection processes at the interfaces: the standard Andreev reflection at the interface between the superconductor and the exciton condensate, and a coherent crossed reflection at the semimetal-exciton-condensate interface that converts electrons from one layer into the other. We show that the differential conductance of the junction shows a minimum at voltages of the order of Γ /e . Such a minimum can be seen as a direct hallmark of the existence of the gapped excitonic state.

  9. Chamber transport

    International Nuclear Information System (INIS)

    Olson, Craig L.

    2001-01-01

    Heavy ion beam transport through the containment chamber plays a crucial role in all heavy ion fusion (HIF) scenarios. Here, several parameters are used to characterize the operating space for HIF beams; transport modes are assessed in relation to evolving target/accelerator requirements; results of recent relevant experiments and simulations of HIF transport are summarized; and relevant instabilities are reviewed. All transport options still exist, including (1) vacuum ballistic transport, (2) neutralized ballistic transport, and (3) channel-like transport. Presently, the European HIF program favors vacuum ballistic transport, while the US HIF program favors neutralized ballistic transport with channel-like transport as an alternate approach. Further transport research is needed to clearly guide selection of the most attractive, integrated HIF system

  10. Control of ZnO Nanorod Defects to Enhance Carrier Transportation in p-Cu₂O/i-ZnO Nanorods/n-IGZO Heterojunction.

    Science.gov (United States)

    Ke, Nguyen Huu; Trinh, Le Thi Tuyet; Mung, Nguyen Thi; Loan, Phan Thi Kieu; Tuan, Dao Anh; Truong, Nguyen Huu; Tran, Cao Vinh; Hung, Le Vu Tuan

    2017-01-01

    The p-Cu₂O/i-ZnO nanorods/n-IGZO heterojunctions were fabricated by electrochemical and sputtering method. ZnO nanorods were grown on conductive indium gallium zinc oxide (IGZO) thin film and then p-Cu₂O layer was deposited on ZnO nanorods to form the heterojunction. ZnO nanorods play an important role in carrier transport mechanisms and performance of the junction. The changing of defects in ZnO nanorods by annealing samples in air and vacuum have studied. The XRD, photoluminescence (PL) spectroscopy, and FTIR were used to study about structure, and defects in ZnO nanorods. The SEM, i–V characteristics methods were also used to define structure, electrical properties of the heterojunctions layers. The results show that the defects in ZnO nanorods affected remarkably on performance of heterojunctions of solar cells.

  11. Observation of enhanced radial transport of energetic ion due to energetic particle mode destabilized by helically-trapped energetic ion in the Large Helical Device

    Science.gov (United States)

    Ogawa, K.; Isobe, M.; Kawase, H.; Nishitani, T.; Seki, R.; Osakabe, M.; LHD Experiment Group

    2018-04-01

    A deuterium experiment was initiated to achieve higher-temperature and higher-density plasmas in March 2017 in the Large Helical Device (LHD). The central ion temperature notably increases compared with that in hydrogen experiments. However, an energetic particle mode called the helically-trapped energetic-ion-driven resistive interchange (EIC) mode is often excited by intensive perpendicular neutral beam injections on high ion-temperature discharges. The mode leads to significant decrease of the ion temperature or to limiting the sustainment of the high ion-temperature state. To understand the effect of EIC on the energetic ion confinement, the radial transport of energetic ions is studied by means of the neutron flux monitor and vertical neutron camera newly installed on the LHD. Decreases of the line-integrated neutron profile in core channels show that helically-trapped energetic ions are lost from the plasma.

  12. Enhancement of marine cloud albedo via controlled sea spray injections: a global model study of the influence of emission rates, microphysics and transport

    Directory of Open Access Journals (Sweden)

    H. Korhonen

    2010-05-01

    Full Text Available Modification of cloud albedo by controlled emission of sea spray particles into the atmosphere has been suggested as a possible geoengineering option to slow global warming. Previous global studies have imposed changes in cloud drop concentration in low level clouds to explore the radiative and climatic effects. Here, we use a global aerosol transport model to quantify how an imposed flux of sea spray particles affects the natural aerosol processes, the particle size distribution, and concentrations of cloud drops. We assume that the proposed fleet of vessels emits sea spray particles with a wind speed-dependent flux into four regions of persistent stratocumulus cloud off the western coasts of continents. The model results show that fractional changes in cloud drop number concentration (CDNC vary substantially between the four regions because of differences in wind speed (which affects the spray efficiency of the vessels, transport and particle deposition rates, and because of variations in aerosols from natural and anthropogenic sources. Using spray emission rates comparable to those implied by previous studies we find that the predicted CDNC changes are very small (maximum 20% and in one of the four regions even negative. The weak or negative effect is because the added particles suppress the in-cloud supersaturation and prevent existing aerosol particles from forming cloud drops. A scenario with five times higher emissions (considerably higher than previously assumed increases CDNC on average by 45–163%, but median concentrations are still below the 375 cm−3 assumed in previous studies. An inadvertent effect of the spray emissions is that sulphur dioxide concentrations are suppressed by 1–2% in the seeded regions and sulphuric acid vapour by 64–68% due to chemical reactions on the additional salt particles. The impact of this suppression on existing aerosol is negligible in the model, but should be investigated further in

  13. Splitting efficiency and interference effects in a Cooper pair splitter based on a triple quantum dot with ferromagnetic contacts

    Science.gov (United States)

    Bocian, Kacper; Rudziński, Wojciech; Weymann, Ireneusz

    2018-05-01

    We theoretically study the spin-resolved subgap transport properties of a Cooper pair splitter based on a triple quantum dot attached to superconducting and ferromagnetic leads. Using the Keldysh Green's function formalism, we analyze the dependence of the Andreev conductance, Cooper pair splitting efficiency, and tunnel magnetoresistance on the gate and bias voltages applied to the system. We show that the system's transport properties are strongly affected by spin dependence of tunneling processes and quantum interference between different local and nonlocal Andreev reflections. We also study the effects of finite hopping between the side quantum dots on the Andreev current. This allows for identifying the optimal conditions for enhancing the Cooper pair splitting efficiency of the device. We find that the splitting efficiency exhibits a nonmonotonic dependence on the degree of spin polarization of the leads and the magnitude and type of hopping between the dots. An almost perfect splitting efficiency is predicted in the nonlinear response regime when the energies of the side quantum dots are tuned to the energies of the corresponding Andreev bound states. In addition, we analyzed features of the tunnel magnetoresistance (TMR) for a wide range of the gate and bias voltages, as well as for different model parameters, finding the corresponding sign changes of the TMR in certain transport regimes. The mechanisms leading to these effects are thoroughly discussed.

  14. Downregulation of eIF4G by microRNA-503 enhances drug sensitivity of MCF-7/ADR cells through suppressing the expression of ABC transport proteins.

    Science.gov (United States)

    Pan, Xia; Yang, Xiaoyan; Zang, Jinglei; Zhang, Si; Huang, Nan; Guan, Xinxin; Zhang, Jianhua; Wang, Zhihui; Li, Xi; Lei, Xiaoyong

    2017-06-01

    Overexpression of adenosine triphosphate-binding cassette (ABC) transport protein is emerging as a critical contributor to anticancer drug resistance. The eukaryotic translation initiation factor (eIF) 4F complex, the key modulator of mRNA translation, is regulated by the phosphoinositide 3-kinase-AKT-mammalian target of rapamycin pathway in anticancer drug-resistant tumors. The present study demonstrated the roles of ABC translation protein alterations in the acquisition of the Adriamycin (ADM)-resistant phenotype of MCF-7 human breast cells. Quantitative polymerase chain reaction and western blot analysis were applied to examine the differences in mRNA and protein levels, respectively. It was found that the expression of the ABC sub-family B member 1, ABC sub-family C member 1 and ABC sub-family G member 2 transport proteins were upregulated in MCF-7/ADR cells. An MTT assay was used to detect the cell viability, from the results MCF-7/ADR cells were less sensitive to ADM, tamoxifen (TAM) and taxol (TAX) treatment compared with MCF-7 cells. We predicted that the 3'-untranslated region of eukaryotic translation initiation factor 4-γ 1 (eIF4G) contains a potential miRNA binding site for microRNA (miR)-503 through using computational programs. These binding sites were confirmed by luciferase reporter assays. eIF4G mRNA degradation was accelerated in cells transfected with miR-503 mimics. Furthermore, it was demonstrated that eIF4G and ABC translation proteins were significantly downregulated in MCF-7/ADR cells after transfection with miR-503. It was found that miR-503 mimics could sensitize the cells to treatment with ADM, TAM and TAX. These findings demonstrated for the first time that eIF4G acted as a key factor in MCF-7/ADR cells, and may be an efficient agent for preventing and reversing multi-drug resistance in breast cancer.

  15. Effects of the gate dielectric on the subthreshold transport of carbon nanotube network transistors grown by using plasma-enhanced chemical vapor deposition

    International Nuclear Information System (INIS)

    Jeong, Seung Geun; Park, Wan Jun

    2010-01-01

    In this study, we investigated the subthreshold slope of random network carbon nanotube transistors with different geometries and passivations. Single-wall carbon nanotubes with lengths of 1-2 m were grown by using plasma-enhanced chemical vapor deposition to form the transistor channels. A critical channel length, where the subthreshold slope was saturated, of 7 μm was obtained. This was due to the percolational behavior of the nanotube random networks. With the dielectric passivation, the subthreshold slope was dramatically reduced from 9 V/decade to 0.9 V/decade by reducing interfacial trap sites, which then reduced the interface capacitance between the nanotube network and the gate dielectric.

  16. Enhancing the Performance of Quantum Dot Light-Emitting Diodes Using Room-Temperature-Processed Ga-Doped ZnO Nanoparticles as the Electron Transport Layer

    KAUST Repository

    Cao, Sheng

    2017-04-19

    Colloidal ZnO nanoparticle (NP) films are recognized as efficient electron transport layers (ETLs) for quantum dot light-emitting diodes (QD-LEDs) with good stability and high efficiency. However, because of the inherently high work function of such films, spontaneous charge transfer occurs at the QD/ZnO interface in such a QD-LED, thus leading to reduced performance. Here, to improve the QD-LED performance, we prepared Ga-doped ZnO NPs with low work functions and tailored band structures via a room-temperature (RT) solution process without the use of bulky organic ligands. We found that the charge transfer at the interface between the CdSe/ZnS QDs and the doped ZnO NPs was significantly weakened because of the incorporated Ga dopants. Remarkably, the as-assembled QD-LEDs, with Ga-doped ZnO NPs as the ETLs, exhibited superior luminances of up to 44 000 cd/m2 and efficiencies of up to 15 cd/A, placing them among the most efficient red-light QD-LEDs ever reported. This discovery provides a new strategy for fabricating high-performance QD-LEDs by using RT-processed Ga-doped ZnO NPs as the ETLs, which could be generalized to improve the efficiency of other optoelectronic devices.

  17. Doubling the CO{sub 2} concentration enhanced the activity of carbohydrate-metabolism enzymes, source carbohydrate production, photoassimilate transport, and sink strength for Opuntia ficus-indica

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Ning; Nobel, P.S. [Univ. of California, Los Angeles, CA (United States)

    1996-03-01

    After exposure to a doubled CO{sub 2} concentration of 750 {mu}mol mol{sup -1} air for about 3 months, glucose and starch in the chlorenchyma of basal cladodes of Opuntia ficus-indica increased 175 and 57%, respectively, compared with the current CO{sub 2} concentration of 370 {mu}mol mol{sup -1}, but sucrose content was virtually unaffected. Doubling the CO{sub 2} concentration increased the noncturnal malate production in basal cladodes by 75%, inorganic phosphate (Pi) by 32% soluble starch synthase activity by 30%, and sucrose-Pi synthase activity by 146%, but did not affect the activity of hexokinase. Doubling CO{sub 2} accelerated phloem transport of sucrose out of the basal cladodes, resulting in a 73% higher dry weight for the daughter cladodes. Doubling CO{sub 2} increased the glucose content in 14-d-old daughter cladodes by 167%, increased nocturnal malate production by 22%, decreased total amino acid content by 61%, and increased soluble starch synthase activity by 30% and sucrose synthase activity by 62%. No downward acclimation of photosynthesis during long-term exposure to elevated CO{sub 2} concentrations occurs for O. ficus-indica, consistent with its higher source capacity and sink strength than under current CO{sub 2}. These changes apparently do not result in Pi limitation of photosynthesis or suppression of genes governing photosynthesis for this perennial Crassulacean acid metabolism species, as occur for some annual crops.

  18. Induction of system A amino acid transport activity through long-term treatment with ouabain: possible correlation with enhanced (Na/sup +//K/sup +/)ATPase activity

    Energy Technology Data Exchange (ETDEWEB)

    Schenerman, M.A.; Leister, K.J.; Wang, S.Y.; Racker, E.

    1987-05-01

    Mouse embryo fibroblast cells (C3H-10T1/2) and the methylcholanthrene-transformed derivative (MCA-10T1/2) were treated with basal modified Eagles medium at varying ouabain concentrations ranging from 0.05 mM to 0.5 mM for 16 h in culture. After replacing the ouabain-containing medium with BME, System A (/sup 3/H-AlB uptake) and the (Na/sup +//K/sup +/)ATPase pump activity (ouabain-sensitive /sup 86/Rb/sup +/ uptake) was increased 10-fold and 3-fold, respectively (at 0.4 mM ouabain) in confluent C3H-10T1/2 cells. System A and the (Na/sup +//K/sup +/)ATPase activity was increased 15-fold and 5-fold, respectively in confluent MCA-10T1/2 cells but the increase was maximal at 0.2 mM ouabain. This treatment with ouabain increased the (Na/sup +/)/sub i//(K/sup +/)/sub i/ as measured by atomic absorption, and thereby decreased the Na/sup +/ and K/sup +/ electrochemical gradients. Their data show that the transformed cells were more sensitive to the internal ion inversion by ouabain than the C3H-10T1/2 cells. It appears, from data on hypertonicity and lipophilic cations that neither the chemical Na/sup +/ gradient nor the negative membrane potential are the primary driving forces of System A transport.

  19. Induction of system A amino acid transport activity through long-term treatment with ouabain: possible correlation with enhanced (Na+/K+)ATPase activity

    International Nuclear Information System (INIS)

    Schenerman, M.A.; Leister, K.J.; Wang, S.Y.; Racker, E.

    1987-01-01

    Mouse embryo fibroblast cells (C3H-10T1/2) and the methylcholanthrene-transformed derivative (MCA-10T1/2) were treated with basal modified Eagles medium at varying ouabain concentrations ranging from 0.05 mM to 0.5 mM for 16 h in culture. After replacing the ouabain-containing medium with BME, System A ( 3 H-AlB uptake) and the (Na + /K + )ATPase pump activity (ouabain-sensitive 86 Rb + uptake) was increased 10-fold and 3-fold, respectively (at 0.4 mM ouabain) in confluent C3H-10T1/2 cells. System A and the (Na + /K + )ATPase activity was increased 15-fold and 5-fold, respectively in confluent MCA-10T1/2 cells but the increase was maximal at 0.2 mM ouabain. This treatment with ouabain increased the [Na + ]/sub i//[K + ]/sub i/ as measured by atomic absorption, and thereby decreased the Na + and K + electrochemical gradients. Their data show that the transformed cells were more sensitive to the internal ion inversion by ouabain than the C3H-10T1/2 cells. It appears, from data on hypertonicity and lipophilic cations that neither the chemical Na + gradient nor the negative membrane potential are the primary driving forces of System A transport

  20. Enhanced Lithium Ion Transport by Superionic Pathways Formed on the Surface of Two-dimensional Structured Li0.85Na0.15V3O8 for High-Performance Lithium Ion Batteries

    International Nuclear Information System (INIS)

    Lu, Xuena; Shang, Yu; Zhang, Sen; Deng, Chao

    2015-01-01

    Highlights: • Li 0.85 Na 0.15 V 3 O 8 nanosheet with superionic conductive layer was constructed. • Li x V 2 O 5 surface layer provides facile pathways for lithium migration. • Li x V 2 O 5 -Li 0.85 Na 0.15 V 3 O 8 composite displays good high rate capability. - Abstract: Poor ion transport and rate capability are the main challenges for LiV 3 O 8 as cathode material for lithium ion batteries. Here we report a novel strategy for enhancing lithium ion transport by building superionic pathways on the surface of Li 0.85 Na 0.15 V 3 O 8 nanosheet. The two-dimensional Li 0.85 Na 0.15 V 3 O 8 nanoparticle with an ion conductive layer of Li x V 2 O 5 on its surface is constructed by a modified sol–gel strategy with carefully controlled sodium incorporation and elements stoichiometry. Ultrathin Li x V 2 O 5 surface layer not only provides facile pathways for lithium migration, but also increases the structure stability during cycling. The Li x V 2 O 5 -Li 0.85 Na 0.15 V 3 O 8 composite displays good high rate capability of 172.3 mAh g −1 at 5C and excellent cycling stability of 98.9% over fifty cycles. This superior electrochemical property is attributed to the occupation of lithium site by Na + in LiV 3 O 8 host crystals and the surface superionic pathways of Li x V 2 O 5 phase. Therefore, the advantages of both high ion transport and the structure stabilization in present study put forward a new strategy for achieving high-performance LiV 3 O 8 electrode material with tailored nanoarchitecture

  1. Transport phenomena

    International Nuclear Information System (INIS)

    Kirczenow, G.; Marro, J.

    1974-01-01

    Some simple remarks on the basis of transport theory. - Entropy, dynamics and scattering theory. - Response, relaxation and fluctuation. - Fluctuating hydrodynamics and renormalization of susceptibilities and transport coefficients. - Irreversibility of the transport equations. - Ergodic theory and statistical mechanics. - Correlation functions in Heisenberg magnets. - On the Enskog hard-sphere kinetic eqquation and the transport phenomena of dense simple gases. - What can one learn from Lorentz models. - Conductivity in a magnetic field. - Transport properties in gases in presence of external fields. - Transport properties of dilute gases with internal structure. (orig.) [de

  2. Does the low hole transport mass in and Si nanowires lead to mobility enhancements at high field and stress: A self-consistent tight-binding study

    Science.gov (United States)

    Kotlyar, R.; Linton, T. D.; Rios, R.; Giles, M. D.; Cea, S. M.; Kuhn, K. J.; Povolotskyi, Michael; Kubis, Tillmann; Klimeck, Gerhard

    2012-06-01

    The hole surface roughness and phonon limited mobility in the silicon , , and square nanowires under the technologically important conditions of applied gate bias and stress are studied with the self-consistent Poisson-sp3d5s*-SO tight-binding bandstructure method. Under an applied gate field, the hole carriers in a wire undergo a volume to surface inversion transition diminishing the positive effects of the high and valence band nonparabolicities, which are known to lead to the large gains of the phonon limited mobility at a zero field in narrow wires. Nonetheless, the hole mobility in the unstressed wires down to the 5 nm size remains competitive or shows an enhancement at high gate field over the large wire limit. Down to the studied 3 nm sizes, the hole mobility is degraded by strong surface roughness scattering in and wires. The channels are shown to experience less surface scattering degradation. The physics of the surface roughness scattering dependence on wafer and channel orientations in a wire is discussed. The calculated uniaxial compressive channel stress gains of the hole mobility are found to reduce in the narrow wires and at the high field. This exacerbates the stressed mobility degradation with size. Nonetheless, stress gains of a factor of 2 are obtained for wires down to 3 nm size at a 5×1012 cm-2 hole inversion density per gate area.

  3. Thermal Gradient During Vacuum-Deposition Dramatically Enhances Charge Transport in Organic Semiconductors: Toward High-Performance N-Type Organic Field-Effect Transistors.

    Science.gov (United States)

    Kim, Joo-Hyun; Han, Singu; Jeong, Heejeong; Jang, Hayeong; Baek, Seolhee; Hu, Junbeom; Lee, Myungkyun; Choi, Byungwoo; Lee, Hwa Sung

    2017-03-22

    A thermal gradient distribution was applied to a substrate during the growth of a vacuum-deposited n-type organic semiconductor (OSC) film prepared from N,N'-bis(2-ethylhexyl)-1,7-dicyanoperylene-3,4:9,10-bis(dicarboxyimide) (PDI-CN2), and the electrical performances of the films deployed in organic field-effect transistors (OFETs) were characterized. The temperature gradient at the surface was controlled by tilting the substrate, which varied the temperature one-dimensionally between the heated bottom substrate and the cooled upper substrate. The vacuum-deposited OSC molecules diffused and rearranged on the surface according to the substrate temperature gradient, producing directional crystalline and grain structures in the PDI-CN2 film. The morphological and crystalline structures of the PDI-CN2 thin films grown under a vertical temperature gradient were dramatically enhanced, comparing with the structures obtained from either uniformly heated films or films prepared under a horizontally applied temperature gradient. The field effect mobilities of the PDI-CN2-FETs prepared using the vertically applied temperature gradient were as high as 0.59 cm 2 V -1 s -1 , more than a factor of 2 higher than the mobility of 0.25 cm 2 V -1 s -1 submitted to conventional thermal annealing and the mobility of 0.29 cm 2 V -1 s -1 from the horizontally applied temperature gradient.

  4. Transportable hyperpolarized metabolites

    Science.gov (United States)

    Ji, Xiao; Bornet, Aurélien; Vuichoud, Basile; Milani, Jonas; Gajan, David; Rossini, Aaron J.; Emsley, Lyndon; Bodenhausen, Geoffrey; Jannin, Sami

    2017-01-01

    Nuclear spin hyperpolarization of 13C-labelled metabolites by dissolution dynamic nuclear polarization can enhance the NMR signals of metabolites by several orders of magnitude, which has enabled in vivo metabolic imaging by MRI. However, because of the short lifetime of the hyperpolarized magnetization (typically <1 min), the polarization process must be carried out close to the point of use. Here we introduce a concept that markedly extends hyperpolarization lifetimes and enables the transportation of hyperpolarized metabolites. The hyperpolarized sample can thus be removed from the polarizer and stored or transported for use at remote MRI or NMR sites. We show that hyperpolarization in alanine and glycine survives 16 h storage and transport, maintaining overall polarization enhancements of up to three orders of magnitude. PMID:28072398

  5. Origin and enhancement of spin polarized current in diluted magnetic oxides by oxygen vacancies

    Energy Technology Data Exchange (ETDEWEB)

    Chou, Hsiung, E-mail: hchou@mail.nsysu.edu.tw; Yang, Kung-Shang; Tsao, Yao-Chung; Dwivedi, G. D.; Lin, Cheng-Pang [Department of Physics, National Sun Yat-Sen University, 70, Lienhai Road, Gushan District, Kaohsiung 804, Taiwan (China); Sun, Shih-Jye [Department of Applied Physics, National Kaohsiung University, 700, Gaoxiongdaxue Rd., Nanzi District, Kaohsiung 811, Taiwan (China); Lin, L. K.; Lee, S. F. [Institute of Physics, Academia Sinica, 128 Academia Road, Section 2, Nankang, Taipei 115, Taiwan (China)

    2016-04-04

    Spin polarized current (SPC) is a crucial characteristic of diluted magnetic oxides due to the potential application of oxides in spintronic devices. However, most research has been focused on ferromagnetic properties rather than polarization of electric current, because direct measurements are difficult and the origin of SPC has yet to be fully understood. The method to increase the SPC percentage is beyond practical consideration at present. To address this problem, we focus on the role of oxygen vacancies (V{sub O}) on SPC, which are controlled by growing the Co-doped ZnO thin-films at room temperature in a reducing atmosphere [Ar + (1%–30%)H{sub 2}]. We found that the conductivity increases with an increase of V{sub O} via two independent channels: the variable range hopping (VRH) within localized states and the itinerant transport in the conduction band. The point contact Andreev reflection measurements at 4.2 K, where the electric conduction is governed only by the VRH mechanism, prove that the current flowing in the VRH hopping channel is SPC. The percentage of SPC increases with the introduction of V{sub O} and increase in its concentration. The transport measurement shows that by manipulating V{sub O}, one can control the percentage of VRH hopping conduction such that it can even dominate room temperature conduction. The highest achieved SPC ratio at room temperature was 80%.

  6. Capriccio For Strings: Collision-Mediated Parallel Transport in Curved Landscapes and Conifold-Enhanced Hierarchies among Mirror Quintic Flux Vacua

    Science.gov (United States)

    Eckerle, Kate

    This dissertation begins with a review of Calabi-Yau manifolds and their moduli spaces, flux compactification largely tailored to the case of type IIb supergravity, and Coleman-De Luccia vacuum decay. The three chapters that follow present the results of novel research conducted as a graduate student. Our first project is concerned with bubble collisions in single scalar field theories with multiple vacua. Lorentz boosted solitons traveling in one spatial dimension are used as a proxy to the colliding 3-dimensional spherical bubble walls. Recent work found that at sufficiently high impact velocities collisions between such bubble vacua are governed by "free passage" dynamics in which field interactions can be ignored during the collision, providing a systematic process for populating local minima without quantum nucleation. We focus on the time period that follows the bubble collision and provide evidence that, for certain potentials, interactions can drive significant deviations from the free passage bubble profile, thwarting the production of a new patch with different field value. However, for simple polynomial potentials a fine-tuning of vacuum locations is required to reverse the free passage kick enough that the field in the collision region returns to the original bubble vacuum. Hence we deem classical transitions mediated by free passage robust. Our second project continues with soliton collisions in the limit of relativistic impact velocity, but with the new feature of nontrivial field space curvature. We establish a simple geometrical interpretation of such collisions in terms of a double family of field profiles whose tangent vector fields stand in mutual parallel transport. This provides a generalization of the well-known limit in flat field space (free passage). We investigate the limits of this approximation and illustrate our analytical results with numerical simulations. In our third and final project we investigate the distribution of field

  7. Polymorphism in the Plasmodium falciparum chloroquine-resistance transporter protein links verapamil enhancement of chloroquine sensitivity with the clinical efficacy of amodiaquine

    Directory of Open Access Journals (Sweden)

    Warhurst David C

    2003-09-01

    Full Text Available Abstract Background Chloroquine accumulates in the acidic digestive vacuole of the intraerythrocytic malaria parasite, and prevents the detoxication of haematin released during haemoglobin digestion. Changes in protein PfCRT in the digestive vacuole membrane of growing intra-erythrocytic stages of Plasmodium falciparum are crucial for resistance. Expressed in yeast, PfCRT resembles an anion channel. Depressed anion channel function could increase intralysosomal pH to reduce entry of basic drug, or enhanced function could reduce drug interaction with target haematin. The most important resistance-associated change is from positively-charged lysine-76 to neutral threonine which could facilitate drug efflux through a putative channel. It has been proposed that the resistance-reversing effect of verapamil is due to hydrophobic binding to the mutated PfCRT protein, and replacement of the lost positive charge, which repels the access of 4-aminoquinoline cations, thus partially restoring sensitivity. Desethylamodiaquine, the active metabolite of amodiaquine, which has significant activity in chloroquine-resistance, may also act similarly on its own. Methods Changes in physicochemical parameters in different CQ-resistant PfCRT sequences are analysed, and correlations with drug activity on lines transfected with different alleles of the pfcrt gene are examined. Results and conclusions The results support the idea that PfCRT is a channel which, in resistant parasites, can allow efflux of chloroquine from the digestive vacuole. Activity of the chloroquine/verapamil combination and of desethylamodiaquine both correlate with the mean hydrophobicity of PfCRT residues 72-76. This may partly explain clinical-resistance to amodiaquine found in the first chloroquine-resistant malaria cases from South America and enables tentative prediction of amodiaquine's clinical activity against novel haplotypes of PfCRT.

  8. Transport, logistics and the region

    NARCIS (Netherlands)

    Langen, de P.W.

    2010-01-01

    Cargo transport and logistics have a huge impact on sustainable (regional) economic development. Two broad (policy) challenges are center stage: enhancing co-location of logistics activities and improving efficiency in intermodal transport chains. Academic research can provide relevant insights for

  9. Neurotransmitter transporters

    DEFF Research Database (Denmark)

    Gether, Ulrik; Andersen, Peter H; Larsson, Orla M

    2006-01-01

    The concentration of neurotransmitters in the extracellular space is tightly controlled by distinct classes of membrane transport proteins. This review focuses on the molecular function of two major classes of neurotransmitter transporter that are present in the cell membrane of neurons and....... Recent research has provided substantial insight into the structure and function of these transporters. In particular, the recent crystallizations of bacterial homologs are of the utmost importance, enabling the first reliable structural models of the mammalian neurotransmitter transporters...

  10. In vivo transport of Gd-DTPA2- into human meniscus and cartilage assessed with delayed gadolinium-enhanced MRI of cartilage (dGEMRIC)

    Science.gov (United States)

    2014-01-01

    Background Impaired stability is a risk factor in knee osteoarthritis (OA), where the whole joint and not only the joint cartilage is affected. The meniscus provides joint stability and is involved in the early pathological progress of OA. Delayed gadolinium-enhanced MRI of cartilage (dGEMRIC) has been used to identify pre-radiographic changes in the cartilage in OA, but has been used less commonly to examine the meniscus, and then using only a double dose of the contrast agent. The purpose of this study was to enable improved early OA diagnosis by investigate the temporal contrast agent distribution in the meniscus and femoral cartilage simultaneously, in healthy volunteers, using 3D dGEMRIC at two different doses of the contrast agent Gd-DTPA2-. Methods The right knee in 12 asymptomatic volunteers was examined using a 3D Look-Locker sequence on two occasions after an intravenous injection of a double or triple dose of Gd-DTPA2- (0.2 or 0.3 mmol/kg body weight). The relaxation time (T1) and relaxation rate (R1 = 1/T1) were measured in the meniscus and femoral cartilage before, and 60, 90, 120 and 180 minutes after injection, and the change in relaxation rate (ΔR1) was calculated. Paired t-test and Analysis of Variance (ANOVA) were used for statistical evaluation. Results The triple dose yielded higher concentrations of Gd-DTPA2- in the meniscus and cartilage than the double dose, but provided no additional information. The observed patterns of ΔR1 were similar for double and triple doses of the contrast agent. ΔR1 was higher in the meniscus than in femoral cartilage in the corresponding compartments at all time points after injection. ΔR1 increased until 90-180 minutes in both the cartilage and the meniscus (p meniscus at all time points (p meniscus, than in the avascular central part of the posterior medial meniscus during the first 60 minutes (p meniscus and cartilage simultaneously using dGEMRIC, preferably 90 minutes after the injection of a

  11. Quantum transport in new two-dimensional heterostructures: Thin films of topological insulators, phosphorene

    Science.gov (United States)

    Majidi, Leyla; Zare, Moslem; Asgari, Reza

    2018-06-01

    The unusual features of the charge and spin transport characteristics are investigated in new two-dimensional heterostructures. Intraband specular Andreev reflection is realized in a topological insulator thin film normal/superconducting junction in the presence of a gate electric field. Perfect specular electron-hole conversion is shown for different excitation energy values in a wide experimentally available range of the electric field and also for all angles of incidence when the excitation energy has a particular value. It is further demonstrated that the transmission probabilities of the incoming electrons from different spin subbands to the monolayer phosphorene ferromagnetic/normal/ferromagnetic (F/N/F) hybrid structure have different behavior with the angle of incidence and perfect transmission occurs at defined angles of incidence to the proposed structure with different length of the N region, and different alignments of magnetization vectors. Moreover, the sign change of the spin-current density is demonstrated by tuning the chemical potential and exchange field of the F region.

  12. Sustainable Transportation

    DEFF Research Database (Denmark)

    Hall, Ralph P.; Gudmundsson, Henrik; Marsden, Greg

    2014-01-01

    The transportation system is the backbone of economic and social progress and the means by which humans access goods and services and connect with one another. Yet, as the scale of transportation activities has grown worldwide, so too have the negative environmental, social, and economic impacts...... that relate to the construction and maintenance of transportation infrastructure and the operation or use of the different transportation modes. The concept of sustainable transportation emerged in response to these concerns as part of the broader notion of sustainable development. Given the transportation...... sector’s significant contribution to global challenges such as climate change, it is often said that sustainable development cannot be achieved without sustainable transportation....

  13. The Absence of the Transcription Factor Yrr1p, Identified from Comparative Genome Profiling, Increased Vanillin Tolerance Due to Enhancements of ABC Transporters Expressing, rRNA Processing and Ribosome Biogenesis in Saccharomyces cerevisiae.

    Science.gov (United States)

    Wang, Xinning; Liang, Zhenzhen; Hou, Jin; Shen, Yu; Bao, Xiaoming

    2017-01-01

    Enhancing the tolerance of Saccharomyces cerevisiae to inhibitors derived from lignocellulose is conducive to producing biofuel and chemicals using abundant lignocellulosic materials. Vanillin is a major type of phenolic inhibitor in lignocellulose hydrolysates for S. cerevisiae . In the present work, the factors beneficial to vanillin resistance in yeast were identified from the vanillin-resistant strain EMV-8, which was derived from strain NAN-27 by adaptive evolution. We found 450 SNPs and 44 genes with InDels in the vanillin-tolerant strain EMV-8 by comparing the genome sequences of EMV-8 and NAN-27. To investigate the effects of InDels, InDels were deleted in BY4741, respectively. We demonstrated that the deletion of YRR1 improved vanillin tolerance of strain. In the presence of 6 mM vanillin, deleting YRR1 increase the maximum specific growth rate and the vanillin consumption rate by 142 and 51%, respectively. The subsequent transcriptome analysis revealed that deleting YRR1 resulted in changed expression of over 200 genes in the presence of 5 mM vanillin. The most marked changes were the significant up-regulation of the dehydrogenase ADH7 , several ATP-binding cassette (ABC) transporters, and dozens of genes involved in ribosome biogenesis and rRNA processing. Coincidently, the crude enzyme solution of BY4741( yrr1 Δ) exhibited higher NADPH-dependent vanillin reduction activity than control. In addition, overexpressing the ABC transporter genes PDR5, YOR1 , and SNQ2 , as well as the RNA helicase gene DBP2 , increased the vanillin tolerance of strain. Interestingly, unlike the marked changes we mentioned above, under vanillin-free conditions, there are only limited transcriptional differences between wildtype and yrr1 Δ. This indicated that vanillin might act as an effector in Yrr1p-related regulatory processes. The new findings of the relationship between YRR1 and vanillin tolerance, as well as the contribution of rRNA processing and ribosome biogenesis to

  14. Light exposure enhances urea absorption in the fluted giant clam, Tridacna squamosa, and up-regulates the protein abundance of a light-dependent urea active transporter, DUR3-like, in its ctenidium.

    Science.gov (United States)

    Chan, Christabel Y L; Hiong, Kum C; Boo, Mel V; Choo, Celine Y L; Wong, Wai P; Chew, Shit F; Ip, Yuen K

    2018-04-19

    Giant clams live in nutrient-poor reef waters of the Indo-Pacific and rely on symbiotic dinoflagellates ( Symbiodinium spp., also known as zooxanthellae) for nutrients. As the symbionts are nitrogen deficient, the host clam has to absorb exogenous nitrogen and supply it to them. This study aimed to demonstrate light-enhanced urea absorption in the fluted giant clam, Tridacna squamosa , and to clone and characterize the urea active transporter DUR3-like from its ctenidium (gill). The results indicate that T. squamosa absorbs exogenous urea, and the rate of urea uptake in the light was significantly higher than that in darkness. The DUR3-like coding sequence obtained from its ctenidium comprised 2346 bp, encoding a protein of 782 amino acids and 87.0 kDa. DUR3-like was expressed strongly in the ctenidium, outer mantle and kidney. Twelve hours of exposure to light had no significant effect on the transcript level of ctenidial DUR3-like However, between 3 and 12 h of light exposure, DUR3-like protein abundance increased progressively in the ctenidium, and became significantly greater than that in the control at 12 h. DUR3-like had an apical localization in the epithelia of the ctenidial filaments and tertiary water channels. Taken together, these results indicate that DUR3-like might participate in light-enhanced urea absorption in the ctenidium of T. squamosa When made available to the symbiotic zooxanthellae that are known to possess urease, the absorbed urea can be metabolized to NH 3 and CO 2 to support amino acid synthesis and photosynthesis, respectively, during insolation. © 2018. Published by The Company of Biologists Ltd.

  15. Nuclear transport

    International Nuclear Information System (INIS)

    Anon.

    2003-01-01

    During january and february 2003, a unique event concerning nuclear transport was reported and rated 1 on the INES scale. This event concerns the absence of a maintenance operation on a shipping cask. This shipping cask was used for several years for nuclear transport inside La-hague site before being re-assigned to transport on public thoroughfare. The re-assignment of the cask should have been preceded and conditioned by a maintenance operation whose purpose is to check the efficiency of its radiation shield. During this period 2 on-site inspections concerning the transport of nuclear materials were performed. (A.C.)

  16. Ocean transportation

    National Research Council Canada - National Science Library

    Frankel, Ernst G; Marcus, Henry S

    1973-01-01

    .... This analysis starts with a review of ocean transportation demand and supply including projections of ship capacity demand and world shipbuilding capacity under various economic and political assumptions...

  17. Enhanced two dimensional electron gas transport characteristics in Al2O3/AlInN/GaN metal-oxide-semiconductor high-electron-mobility transistors on Si substrate

    International Nuclear Information System (INIS)

    Freedsman, J. J.; Watanabe, A.; Urayama, Y.; Egawa, T.

    2015-01-01

    The authors report on Al 2 O 3 /Al 0.85 In 0.15 N/GaN Metal-Oxide-Semiconductor High-Electron-Mobility Transistor (MOS-HEMT) on Si fabricated by using atomic layer deposited Al 2 O 3 as gate insulator and passivation layer. The MOS-HEMT with the gate length of 2 μm exhibits excellent direct-current (dc) characteristics with a drain current maximum of 1270 mA/mm at a gate bias of 3 V and an off-state breakdown voltage of 180 V for a gate-drain spacing of 4 μm. Also, the 1 μm-gate MOS-HEMT shows good radio-frequency (rf) response such as current gain and maximum oscillation cut-off frequencies of 10 and 34 GHz, respectively. The capacitance-voltage characteristics at 1 MHz revealed significant increase in two-dimensional electron gas (2DEG) density for the MOS-HEMT compared to conventional Schottky barrier HEMTs. Analyses using drain-source conductivity measurements showed improvements in 2DEG transport characteristics for the MOS-HEMT. The enhancements in dc and rf performances of the Al 2 O 3 /Al 0.85 In 0.15 N/GaN MOS-HEMT are attributed to the improvements in 2DEG characteristics

  18. Neutron transport

    International Nuclear Information System (INIS)

    Berthoud, Georges; Ducros, Gerard; Feron, Damien; Guerin, Yannick; Latge, Christian; Limoge, Yves; Santarini, Gerard; Seiler, Jean-Marie; Vernaz, Etienne; Coste-Delclaux, Mireille; M'Backe Diop, Cheikh; Nicolas, Anne; Andrieux, Catherine; Archier, Pascal; Baudron, Anne-Marie; Bernard, David; Biaise, Patrick; Blanc-Tranchant, Patrick; Bonin, Bernard; Bouland, Olivier; Bourganel, Stephane; Calvin, Christophe; Chiron, Maurice; Damian, Frederic; Dumonteil, Eric; Fausser, Clement; Fougeras, Philippe; Gabriel, Franck; Gagnier, Emmanuel; Gallo, Daniele; Hudelot, Jean-Pascal; Hugot, Francois-Xavier; Dat Huynh, Tan; Jouanne, Cedric; Lautard, Jean-Jacques; Laye, Frederic; Lee, Yi-Kang; Lenain, Richard; Leray, Sylvie; Litaize, Olivier; Magnaud, Christine; Malvagi, Fausto; Mijuin, Dominique; Mounier, Claude; Naury, Sylvie; Nicolas, Anne; Noguere, Gilles; Palau, Jean-Marc; Le Pallec, Jean-Charles; Peneliau, Yannick; Petit, Odile; Poinot-Salanon, Christine; Raepsaet, Xavier; Reuss, Paul; Richebois, Edwige; Roque, Benedicte; Royer, Eric; Saint-Jean, Cyrille de; Santamarina, Alain; Serot, Olivier; Soldevila, Michel; Tommasi, Jean; Trama, Jean-Christophe; Tsilanizara, Aime; Behar, Christophe; Provitina, Olivier; Lecomte, Michael; Forestier, Alain; Bender, Alexandra; Parisot, Jean-Francois; Finot, Pierre

    2013-10-01

    This bibliographical note presents a reference book which addresses the study of neutron transport in matter, the study of conditions for a chain reaction and the study of modifications of matter composition due to nuclear reactions. This book presents the main nuclear data, their measurement, assessment and processing, and the spallation. It proposes an overview of methods applied for the study of neutron transport: basic equations and their derived forms, deterministic methods and Monte Carlo method of resolution of the Boltzmann equation, methods of resolution of generalized Bateman equations, methods of time resolution of space kinetics coupled equations. It presents the main calculation codes, discusses the qualification and experimental aspects, and gives an overview of neutron transport applications: neutron transport calculation of reactors, neutron transport coupled with other disciplines, physics of fuel cycle, criticality

  19. Large orbit neoclassical transport

    International Nuclear Information System (INIS)

    Lin, Z.; Tang, W.M.; Lee, W.W.

    1997-01-01

    Neoclassical transport in the presence of large ion orbits is investigated. The study is motivated by the recent experimental results that ion thermal transport levels in enhanced confinement tokamak plasmas fall below the open-quotes irreducible minimum levelclose quotes predicted by standard neoclassical theory. This apparent contradiction is resolved in the present analysis by relaxing the basic neoclassical assumption that the ions orbital excursions are much smaller than the local toroidal minor radius and the equilibrium scale lengths of the system. Analytical and simulation results are in agreement with trends from experiments. The development of a general formalism for neoclassical transport theory with finite orbit width is also discussed. copyright 1997 American Institute of Physics

  20. Animal Transports

    Directory of Open Access Journals (Sweden)

    Diana Ludrovcová

    2016-08-01

    Full Text Available Purpose and Originality: The research is aimed to the animal transports issue, from two points of view – first is the animal cruelty and second is the policy and economic consideration. The goal is to acquaint the readers with the transports risks and its cruelty and evaluation of the economic, political aspects for he involved countries. The study is oriented on more points of view, what is rare in works with a similar theme. Method: This paper examines many issues and examinations from different authors and subsequently summarized the findings with authors own knowledge to one expanded unit. Results: Results proves, that livestock transports have negative impact on animal´s health, environment. Number of transported animals is rising every year. Society: Research familiarize the society with the animal transports, cruelty against animals during them, and influence of transports on some countries, their economy, policy. People get better informed and can form their own opinion on this topic. They may start acting, undertaking some steps to improve the present situation, what could help a lot to animals and environment. Limitations / further research: Future research could show progress and improvement of transports, quality of food supply and economics.

  1. Enhanced two dimensional electron gas transport characteristics in Al{sub 2}O{sub 3}/AlInN/GaN metal-oxide-semiconductor high-electron-mobility transistors on Si substrate

    Energy Technology Data Exchange (ETDEWEB)

    Freedsman, J. J., E-mail: freedy54@gmail.com; Watanabe, A.; Urayama, Y. [Research Center for Nano-Devices and Advanced Materials, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466 8555 (Japan); Egawa, T., E-mail: egawa.takashi@nitech.ac.jp [Research Center for Nano-Devices and Advanced Materials, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466 8555 (Japan); Innovation Center for Multi-Business of Nitride Semiconductors, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466 8555 (Japan)

    2015-09-07

    The authors report on Al{sub 2}O{sub 3}/Al{sub 0.85}In{sub 0.15}N/GaN Metal-Oxide-Semiconductor High-Electron-Mobility Transistor (MOS-HEMT) on Si fabricated by using atomic layer deposited Al{sub 2}O{sub 3} as gate insulator and passivation layer. The MOS-HEMT with the gate length of 2 μm exhibits excellent direct-current (dc) characteristics with a drain current maximum of 1270 mA/mm at a gate bias of 3 V and an off-state breakdown voltage of 180 V for a gate-drain spacing of 4 μm. Also, the 1 μm-gate MOS-HEMT shows good radio-frequency (rf) response such as current gain and maximum oscillation cut-off frequencies of 10 and 34 GHz, respectively. The capacitance-voltage characteristics at 1 MHz revealed significant increase in two-dimensional electron gas (2DEG) density for the MOS-HEMT compared to conventional Schottky barrier HEMTs. Analyses using drain-source conductivity measurements showed improvements in 2DEG transport characteristics for the MOS-HEMT. The enhancements in dc and rf performances of the Al{sub 2}O{sub 3}/Al{sub 0.85}In{sub 0.15}N/GaN MOS-HEMT are attributed to the improvements in 2DEG characteristics.

  2. Ocean transportation

    National Research Council Canada - National Science Library

    Frankel, Ernst G; Marcus, Henry S

    1973-01-01

    .... The discussion of technology considers the ocean transportation system as a whole, and the composite subsystems such as hull, outfit, propulsion, cargo handling, automation, and control and interface technology...

  3. Ocean transportation

    National Research Council Canada - National Science Library

    Frankel, Ernst G; Marcus, Henry S

    1973-01-01

    .... In ocean transportation economics we present investment and operating costs as well as the results of a study of financing of shipping. Similarly, a discussion of government aid to shipping is presented.

  4. Nicaragua - Transportation

    Data.gov (United States)

    Millennium Challenge Corporation — The evaluation examines impacts of the Transportation Project in three ways. First, we calculate economic rates of return associated with reduced user costs for each...

  5. Sediment Transport

    DEFF Research Database (Denmark)

    Liu, Zhou

    Flow and sediment transport are important in relation to several engineering topics, e.g. erosion around structures, backfilling of dredged channels and nearshore morphological change. The purpose of the present book is to describe both the basic hydrodynamics and the basic sediment transport...... mechanics. Chapter 1 deals with fundamentals in fluid mechanics with emphasis on bed shear stress by currents, while chapter 3 discusses wave boundary layer theory. They are both written with a view to sediment transport. Sediment transport in rivers, cross-shore and longshore are dealt with in chapters 2......, 4 and 5, respectively. It is not the intention of the book to give a broad review of the literature on this very wide topic. The book tries to pick up information which is of engineering importance. An obstacle to the study of sedimentation is the scale effect in model tests. Whenever small...

  6. Collisional transport in nonneutral plasmas

    International Nuclear Information System (INIS)

    Dubin, D.H.E.

    1999-01-01

    Classical transport theory grossly underestimates collisionally-driven cross-field transport for plasmas in the parameter regime of r c D , where r c ≡ v-bar/Ω c , λ D 2 ≡ T/4πe 2 n. In current experiments operating in this regime, cross-field test particle transport is observed to be a factor of 10 larger than the prediction of classical theory. Heat conduction is enhanced by up to 300 times over classical theory, and viscosity is up to 10 4 times larger. New guiding center theories of transport due to long-range collisions have been developed that agree with the measurements. Theory also predicts that emission and absorption of plasma waves may further enhance the thermal conduction and viscosity, providing a possible mechanism for anomalous thermal conductivity in the electron channel of fusion plasmas. (author)

  7. RF transport

    International Nuclear Information System (INIS)

    Choroba, Stefan

    2013-01-01

    This paper deals with the techniques of transport of high-power radiofrequency (RF) power from a RF power source to the cavities of an accelerator. Since the theory of electromagnetic waves in waveguides and of waveguide components is very well explained in a number of excellent text books it will limit itself on special waveguide distributions and on a number of, although not complete list of, special problems which sometimes occur in RF power transportation systems. (author)

  8. Public transport

    OpenAIRE

    Lethbridge, Jane

    2008-01-01

    Public transport plays an essential role in enabling people from low income and other disadvantaged groups to access employment and services. It also contributes to the development of social networks and social capital, by helping people to visit friends and relatives and take part in community and other social activities. Public policy makers have begun to recognise that adequate public transport provision can play an important role in reducing social exclusion. [Taken from introductory para...

  9. Orbital transport

    International Nuclear Information System (INIS)

    Oertel, H. Jr.; Koerner, H.

    1993-01-01

    The Third Aerospace Symposium in Braunschweig presented, for the first time, the possibility of bringing together the classical disciplines of aerospace engineering and the natural science disciplines of meteorology and air chemistry in a european setting. In this way, aspects of environmental impact on the atmosphere could be examined quantitatively. An essential finding of the european conference, is the unrestricted agreement of the experts that the given launch frequencies of the present orbital transport result in a negligible amount of pollutants being released in the atmosphere. The symposium does, however, call attention to the increasing need to consider the effect of orbital and atmospheric environmental impact of a future increase in launch frequencies of orbital transport in connection with future space stations. The Third Aerospace Symposium, 'Orbital Transport, Technical, Meteorological and Chemical Aspects', constituted a first forum of discussion for engineers and scientists. Questions of new orbital transport technologies and their environmental impact were to be discussed towards a first consensus. Through the 34 reports and articles, the general problems of space transportation and environmental protection were addressed, as well as particular aspects of high temperatures during reentry in the atmosphere of the earth, precision navigation of flight vehicles or flow behavior and air chemistry in the stratosphere. (orig./CT). 342 figs

  10. Gas transport in porous media

    CERN Document Server

    Ho, Clifford K

    2006-01-01

    This book presents a compilation of state-of-the art studies on gas and vapor transport processes in porous and fractured media. A broad set of models and processes are presented, including advection/diffusion, the Dusty Gas Model, enhanced vapor diffusion, phase change, coupled processes, solid/vapor sorption, and vapor-pressure lowering. Numerous applications are also presented that illustrate these processes and models in current problems facing the scientific community. This book fills a gap in the general area of transport in porous and fractured media; an area that has historically been dominated by studies of liquid-phase flow and transport. This book identifies gas and vapor transport processes that may be important or dominant in various applications, and it exploits recent advances in computational modeling and experimental methods to present studies that distinguish the relative importance of various mechanisms of transport in complex media.

  11. The serotonin transporter: Examination of the changes in transporter affinity induced by ligand binding

    International Nuclear Information System (INIS)

    Humphreys, C.J.

    1989-01-01

    The plasmalemmal serotonin transporter uses transmembrane gradients of Na + , Cl - and K + to accumulate serotonin within blood platelets. Transport is competitively inhibited by the antidepressant imipramine. Like serotonin transport, imipramine binding requires Na + . Unlike serotonin, however, imipramine does not appear to be transported. To gain insight into the mechanism of serotonin transport the author have analyzed the influences of Na + and Cl - , the two ions cotransported with serotonin, on both serotonin transport and the interaction of imipramine and other antidepressant drugs with the plasmalemmal serotonin transporter of human platelets. Additionally, the author have synthesized, purified and characterized the binding of 2-iodoimipramine to the serotonin transporter. Finally, the author have conducted a preliminary study of the inhibition of serotonin transport and imipramine binding produced by dicyclohexylcarbodiimide. My results reveal many instances of positive heterotropic cooperativity in ligand binding to the serotonin transporter. Na + binding enhances the transporters affinity for imipramine and several other antidepressant drugs, and also increases the affinity for Cl - . Cl - enhances the transporters affinity for imipramine, as well as for Na + . At concentrations in the range of its K M for transport serotonin is a competitive inhibitor of imipramine binding. At much higher concentrations, however, serotonin also inhibits imipramines dissociation rate constant. This latter effect which is Na + -independent and species specific, is apparently produced by serotonin binding at a second, low affinity site on, or near, the transporter complex. Iodoimipramine competitively inhibit both [ 3 H]imipramine binding and [ 3 H]serotonin transport

  12. Arterial intelligent transportation systems : infrastructure elements and traveler information requirements.

    Science.gov (United States)

    2009-08-01

    Applying Intelligent Transportation Systems (ITS) to arterial systems allows TxDOT to significantly enhance : transportation system operation efficiency and improve traffic mobility. However, no guidelines are available to : assist TxDOT staff in sel...

  13. Travel and transport

    DEFF Research Database (Denmark)

    Bill, Jan; Roesdahl, Else

    2007-01-01

    On the interrelationship between travel, transport and society; on land transport, sea and river transport, and on winter transport;  on the related technologies and their developments......On the interrelationship between travel, transport and society; on land transport, sea and river transport, and on winter transport;  on the related technologies and their developments...

  14. Transport system

    NARCIS (Netherlands)

    Drenth, K.F.

    1999-01-01

    The transport system comprises at least one road surface (2) and at least one vehicle (4) on wheels (6). The road surface (2) has a substantially bowl-shaped cross section and the vehicle (4) is designed so that the wheels (6) run directly on the road surface (2) while the road surface (2) acts as a

  15. Optimal transport

    CERN Document Server

    Eckmann, B

    2008-01-01

    At the close of the 1980s, the independent contributions of Yann Brenier, Mike Cullen and John Mather launched a revolution in the venerable field of optimal transport founded by G Monge in the 18th century, which has made breathtaking forays into various other domains of mathematics ever since. The author presents a broad overview of this area.

  16. Nuclear transport

    International Nuclear Information System (INIS)

    Anon.

    2001-01-01

    Here is given the decree (2001/1199) of the 10. of december 2001 relative to the passing of safety rules concerning the maritime transport of spent fuels, plutonium and high-level radioactive wastes contained in packages. (O.M.)

  17. Transport fuel

    DEFF Research Database (Denmark)

    Ronsse, Frederik; Jørgensen, Henning; Schüßler, Ingmar

    2014-01-01

    Worldwide, the use of transport fuel derived from biomass increased four-fold between 2003 and 2012. Mainly based on food resources, these conventional biofuels did not achieve the expected emission savings and contributed to higher prices for food commod - ities, especially maize and oilseeds...

  18. 77 FR 71430 - New Agency Information Collection Activity Under OMB Review: Public Transportation Baseline...

    Science.gov (United States)

    2012-11-30

    ... DEPARTMENT OF HOMELAND SECURITY Transportation Security Administration New Agency Information Collection Activity Under OMB Review: Public Transportation Baseline Assessment for Security Enhancement... voluntary site visits with security and operating officials of public transportation systems. This program...

  19. Dwight David Eisenhower Transportation Fellowship Program System -

    Data.gov (United States)

    Department of Transportation — DDETFP is a web-based application used to measure the performance of the DDETFP program, enhance reporting, and evaluate the programs' effectiveness in meeting goals...

  20. Developing strategies for successful communication at public meetings and open houses to enhance the conceptual understanding and awareness of need and purpose, transportation deficiencies, and consequences of not implementing improvements associated with GDOT’s proposed Work program.

    Science.gov (United States)

    2017-01-01

    The research projects purpose was to determine the most effective strategies, methods, and formats to inform the public about Georgia Department of Transportations (GDOT) Work Program. The researchers investigated the United States Department o...

  1. Rail security : some actions taken to enhance passenger and freight rail security, but significant challenges remain : testimony before the Committee on Commerce, Science, and Transportation, U.S. Senate

    Science.gov (United States)

    2004-03-23

    Passenger and freight rail services are important links in the nation's transportation system. Terrorist attacks on passenger and/or freight rail services have the potential to cause widespread injury, loss of life, and economic disruption. The recen...

  2. Transportation Statistics Annual Report 1997

    Energy Technology Data Exchange (ETDEWEB)

    Fenn, M.

    1997-01-01

    This document is the fourth Transportation Statistics Annual Report (TSAR) prepared by the Bureau of Transportation Statistics (BTS) for the President and Congress. As in previous years, it reports on the state of U.S. transportation system at two levels. First, in Part I, it provides a statistical and interpretive survey of the system—its physical characteristics, its economic attributes, aspects of its use and performance, and the scale and severity of unintended consequences of transportation, such as fatalities and injuries, oil import dependency, and environment impacts. Part I also explores the state of transportation statistics, and new needs of the rapidly changing world of transportation. Second, Part II of the report, as in prior years, explores in detail the performance of the U.S. transportation system from the perspective of desired social outcomes or strategic goals. This year, the performance aspect of transportation chosen for thematic treatment is “Mobility and Access,” which complements past TSAR theme sections on “The Economic Performance of Transportation” (1995) and “Transportation and the Environment” (1996). Mobility and access are at the heart of the transportation system’s performance from the user’s perspective. In what ways and to what extent does the geographic freedom provided by transportation enhance personal fulfillment of the nation’s residents and contribute to economic advancement of people and businesses? This broad question underlies many of the topics examined in Part II: What is the current level of personal mobility in the United States, and how does it vary by sex, age, income level, urban or rural location, and over time? What factors explain variations? Has transportation helped improve people’s access to work, shopping, recreational facilities, and medical services, and in what ways and in what locations? How have barriers, such as age, disabilities, or lack of an automobile, affected these

  3. Nuclear transport

    International Nuclear Information System (INIS)

    Anon.

    2002-01-01

    During September and October 2001, 1 event has been reported and classified at the first level of the INES scale. This incident concerns the violation of the European regulation that imposes to any driver of radioactive matter of being the holder of a certificate asserting that he attended a special training. During this period, 13 in-site inspections have been made in places related to nuclear transport. (A.C.)

  4. Hijacking membrane transporters for arsenic phytoextraction

    Science.gov (United States)

    LeBlanc, Melissa S.; McKinney, Elizabeth C.; Meagher, Richard B.; Smith, Aaron P.

    2012-01-01

    Arsenic is a toxic metalloid and recognized carcinogen. Arsenate and arsenite are the most common arsenic species available for uptake by plants. As an inorganic phosphate (Pi) analog, arsenate is acquired by plant roots through endogenous Pi transport systems. Inside the cell, arsenate is reduced to the thiol-reactive form arsenite. Glutathione (GSH)-conjugates of arsenite may be extruded from the cell or sequestered in vacuoles by members of the ATP-binding cassette (ABC) family of transporters. In the present study we sought to enhance both plant arsenic uptake through Pi transporter overexpression, and plant arsenic tolerance through ABC transporter overexpression. We demonstrate that Arabidopsis thaliana plants overexpressing the high-affinity Pi transporter family members, AtPht1;1 or AtPht1;7, are hypersensitive to arsenate due to increased arsenate uptake. These plants do not exhibit increased sensitivity to arsenite. Co-overexpression of the yeast ABC transporter YCF1 in combination with AtPht1;1 or AtPht1;7 suppresses the arsenate-sensitive phenotype while further enhancing arsenic uptake. Taken together, our results support an arsenic transport mechanism in which arsenate uptake is increased through Pi transporter overexpression, and arsenic tolerance is enhanced through YCF1-mediated vacuolar sequestration. This work substantiates the viability of coupling enhanced uptake and vacuolar sequestration as a means for developing a prototypical engineered arsenic hyperaccumulator. PMID:23108027

  5. Transportation System Concept of Operations

    Energy Technology Data Exchange (ETDEWEB)

    N. Slater-Thompson

    2006-08-16

    The Nuclear Waste Policy Act of 1982 (NWPA), as amended, authorized the DOE to develop and manage a Federal system for the disposal of SNF and HLW. OCRWM was created to manage acceptance and disposal of SNF and HLW in a manner that protects public health, safety, and the environment; enhances national and energy security; and merits public confidence. This responsibility includes managing the transportation of SNF and HLW from origin sites to the Repository for disposal. The Transportation System Concept of Operations is the core high-level OCRWM document written to describe the Transportation System integrated design and present the vision, mission, and goals for Transportation System operations. By defining the functions, processes, and critical interfaces of this system early in the system development phase, programmatic risks are minimized, system costs are contained, and system operations are better managed, safer, and more secure. This document also facilitates discussions and understanding among parties responsible for the design, development, and operation of the Transportation System. Such understanding is important for the timely development of system requirements and identification of system interfaces. Information provided in the Transportation System Concept of Operations includes: the functions and key components of the Transportation System; system component interactions; flows of information within the system; the general operating sequences; and the internal and external factors affecting transportation operations. The Transportation System Concept of Operations reflects OCRWM's overall waste management system policies and mission objectives, and as such provides a description of the preferred state of system operation. The description of general Transportation System operating functions in the Transportation System Concept of Operations is the first step in the OCRWM systems engineering process, establishing the starting point for the lower

  6. Transport through hybrid superconducting/ferromagnetic double-path junction

    Energy Technology Data Exchange (ETDEWEB)

    Facio, T.J.S. [Departamento de Física e Química, Universidade Estadual Paulista – UNESP, 15385-000, Ilha Solteira, SP (Brazil); Orellana, P.A. [Departamento de Física, Universidad Técnica Federico Santa Maria, Av. Vicuña Mackenna, 3939, Santiago (Chile); Jurelo, A.R. [Departamento de Física, Universidade Estadual de Ponta Grossa – UEPG, 84030-000, Ponta Grossa, PR (Brazil); Figueira, M.S. [Instituto de Física, Universidade Federal Fluminense, 24210-340, Niterói, RJ (Brazil); Cabrera, G.G. [Instituto de Física ‘Gleb Wataghin’, Universidade Estadual de Campinas – UNICAMP, 13083-859, Campinas, SP (Brazil); Siqueira, E.C., E-mail: ecosta@utfpr.edu.br [Departamento de Física, Universidade Tecnológica Federal do Paraná – UTFPR, 84016-210, Ponta Grossa, PR (Brazil)

    2017-02-05

    In this paper we study a double-path junction formed by a ferromagnetic and a superconductor lead. The first path connects the superconductor and ferromagnet directly while the second path connects these metals through a quantum dot. The whole system works as an Aharonov–Bohm interferometer allowing the study of the interference between these two paths under the presence of spin imbalance and Andreev bound states. We considered the effect of Fano interference on the electronic transmittance through the quantum dot and observed two regimes of conduction depending on the strength of the direct coupling. For the weak coupling regime, the transmittance presented the usual four resonances due to the Andreev bound states whereas for the strong coupling regime the profile was inverted and resonances became anti-resonances. However, even in the strong coupling regime it was possible to observe a central resonance due to the interference between the Andreev bound states. We have also studied the signatures of Fano interference on the average occupation within the quantum dot. The spin accumulation was analyzed and how it depends on the direct coupling and an external magnetic field applied to the system. The results obtained may be used in a possible experimental implementation of this system in order to probe spin related effects in ferromagnetic superconductor nanostructures. - Highlights: • An Aharonov–Bohm interferometer composed by a quantum-dot coupled to a superconductor and ferromagnetic lead is studied. • The transmittance through the QD is determined by the interplay between Andreev and Fano interference. • Spin accumulation within the quantum dot is studied as a function of bias/gate voltages and an external magnetic flux.

  7. Michigan transportation facts & figures : public transportation

    Science.gov (United States)

    2002-08-16

    This on-line document is part of a series, Transportation Facts & Figures, by the Michigan Department of Transportation (MDOT). The Public Transit section of Transportation Facts & Figures cover such topics as intercity bus service, intercity rail se...

  8. Analysis of transport administrators and sustainable transport ...

    African Journals Online (AJOL)

    Analysis of transport administrators and sustainable transport development in Lagos, Ogun and Oyo States, Nigeria. ... A good transportation system planning and management is considered vital for ... EMAIL FULL TEXT EMAIL FULL TEXT

  9. Transporter Classification Database (TCDB)

    Data.gov (United States)

    U.S. Department of Health & Human Services — The Transporter Classification Database details a comprehensive classification system for membrane transport proteins known as the Transporter Classification (TC)...

  10. Dose of 3-methylcholanthrene enhances vitamin C accumulation and mRNA expression of its transporter in the liver of ODS rats and in HepG2 cells.

    Science.gov (United States)

    Sone, Yasuko; Ueta, Etsuko; Sannomaru, Yasuko; Miyake, Noriko; Sone, Hirohito; Otsuka, Yuzuru; Kondo, Kazuo; Kurata, Tadao; Suzuki, Emiko

    2011-01-01

    Polycyclic aromatic hydrocarbon (PAH) compounds including 3-methylcholanthrene induce harmful reactive intermediates and reactive oxygen species. This study reports the effect of 3-methylcholanthrene on the accumulation of vitamin C and the expression of vitamin C transporters. ODS rats were given l-ascorbic acid daily and intraperitoneal injections of 10 mg 3-methylcholanthrene in total. On day 10, vitamin C concentrations and the expression of vitamin C transporter in the tissues were measured. As a result, the levels of sodium-dependent vitamin C transporter (SVCTs) 1 and the l-ascorbic acid concentration in 3-methylcholanthrene-treated livers and hepatocytes have increased significantly. However, the content of vitamin C in the urine and TBARS in the liver have not changed. These results suggest that the administration of 3-methylcholanthrene elevates the requirement for vitamin C via (SVCTs) 1 due to xenobitics-metabolizing, such as the induction of cytochrome P450 family. Copyright © 2011 Wiley Periodicals, Inc.

  11. Energy transport

    International Nuclear Information System (INIS)

    Anon.

    1982-01-01

    The measurement of primary interaction cross sections and the incorporation of these data into Monte Carlo calculations provide detailed information about the initial spatial distribution of absorbed dose. Our theoretical energy transport studies have focused on the use of this information to predict the evolution of chemical species formed as a result of the energy deposition. This effort has led to a stochastic approach to diffusion kinetics that can account for the influence of track structure on the yield of free radicals in the radiolysis of water. Fluorescence studies with pulsed alpha particle and proton beams provided the first experimental test of our stochastic model of tract structure effects. Our experimental studies use time-resolved emission spectroscopy to investigate the mechanism of energy transport in nonpolar liquids. Studies of the concentration dependence of time-resolved emission from solutions of benzene in cyclohexane also show the importance of using low benzene concentrations to minimize the influence of benzene dimers on the emission kinetics

  12. Lymphatic transport and lymph node targeting of methotrexate-conjugated PEGylated dendrimers are enhanced by reducing the length of the drug linker or masking interactions with the injection site.

    Science.gov (United States)

    Ryan, Gemma M; McLeod, Victoria M; Mehta, Dharmini; Kelly, Brian D; Stanislawski, Pauline C; Owen, David J; Kaminskas, Lisa M; Porter, Christopher J H

    2017-11-01

    Drug conjugation to dendrimer-based delivery systems has been shown to enhance delivery to the lymphatic system after subcutaneous administration. Dendrimer interaction with components of the interstitium at the injection site, however, may prevent drainage from the injection site. The current study sought to vary the length of a linker employed to conjugate methotrexate (MTX) to a PEGylated dendrimer, in an attempt to reduce MTX interaction with interstitial binding sites and enhance lymphatic drainage. Dendrimers with shorter linkers resulted in higher lymphatic drainage, presumably via shielding of interaction sites by the PEG mantle, but were not retained in lymph nodes. Improved drainage of dendrimers with longer linkers was achieved through coadministration with dextran to mask interactions at the injection site while maintaining retention within the node. Enhanced drug exposure to the lymph node has the potential to enhance the treatment of lymph-node resident cancer metastases. Copyright © 2017 Elsevier Inc. All rights reserved.

  13. National transportation statistics 2011

    Science.gov (United States)

    2011-04-01

    Compiled and published by the U.S. Department of Transportation's Bureau of Transportation Statistics : (BTS), National Transportation Statistics presents information on the U.S. transportation system, including : its physical components, safety reco...

  14. National Transportation Statistics 2008

    Science.gov (United States)

    2009-01-08

    Compiled and published by the U.S. Department of Transportations Bureau of Transportation Statistics (BTS), National Transportation Statistics presents information on the U.S. transportation system, including its physical components, safety record...

  15. State Transportation Statistics 2012

    Science.gov (United States)

    2013-08-15

    The Bureau of Transportation Statistics (BTS), a part of the U.S. Department of Transportation's (USDOT) Research and Innovative Technology Administration (RITA), presents State Transportation Statistics 2012, a statistical profile of transportation ...

  16. National Transportation Statistics 2009

    Science.gov (United States)

    2010-01-21

    Compiled and published by the U.S. Department of Transportation's Bureau of Transportation Statistics (BTS), National Transportation Statistics presents information on the U.S. transportation system, including its physical components, safety record, ...

  17. State Transportation Statistics 2014

    Science.gov (United States)

    2014-12-15

    The Bureau of Transportation Statistics (BTS) presents State Transportation Statistics 2014, a statistical profile of transportation in the 50 states and the District of Columbia. This is the 12th annual edition of State Transportation Statistics, a ...

  18. Transport device of spent fuel

    International Nuclear Information System (INIS)

    Watanabe, Takashi.

    1976-01-01

    Object: To provide a transport device of spent fuel particularly used in a fast breeder, which can enhance accessibility to travelling mechanism portions and exchangeability thereof to facilitate maintenance in the event of failure. Structure: On a travelling floor, which has a function to shield radioactive rays, extending in a direction of transporting spent fuel and being formed with a break passing through in a direction wall thickness, a travelling body is moved along the break. The travelling body has a support rod member mounted thereon, and the support rod member is moved within the break, the support rod member having a fuel support pocket suspended therefrom. (Furukawa, Y.)

  19. Transport of radioactive substances

    International Nuclear Information System (INIS)

    2014-12-01

    The report on the transport of radioactive substances covers the following topics: facts on radioactive materials transport, safety of the transport of radioactive substances, legal regulations and guidelines: a multiform but consistent system, transport of nuclear fuels, safety during the transport of nuclear fuel, future transport of spent fuel elements and high-level radioactive wastes in Germany.

  20. Formation and collapse of internal transport barrier

    International Nuclear Information System (INIS)

    Fukuyama, A.; Itoh, K.; Itoh, S.I.; Yagi, M.

    1999-01-01

    A theoretical model of internal transport barrier (ITB) is developed. The transport model based on the self-sustained turbulence theory of the current-diffusive ballooning mode is extended to include the effects of ExB rotation shear. Delayed formation of ITB is observed in transport simulations. The influence of finite gyroradius is also discussed. Simulation of the current ramp-up experiment successfully described the radial profile of density, temperature and safety factor. A model of ITB collapse due to magnetic braiding is proposed. Sudden enhancement of transport triggered by overlapping of magnetic islands terminates ITB. The possibility of destabilizing global low-n modes is also discussed. (author)

  1. Speed Limits for Nonvesicular Intracellular Sterol Transport.

    Science.gov (United States)

    Dittman, Jeremy S; Menon, Anant K

    2017-02-01

    Sterol transport between the endoplasmic reticulum (ER) and plasma membrane (PM) occurs by nonvesicular mechanisms requiring sterol transport proteins (STPs). Here we examine the idea that transport is enhanced at membrane contact sites where the ER is closely apposed to the PM. We conclude that sterol desorption from the membrane, rather than STP-mediated diffusion, is rate limiting in the cellular context, so there is no apparent kinetic benefit to having STP-mediated sterol transfer occur at contact sites. Contact sites may instead compartmentalize lipid synthesis or transport machinery, providing opportunities for regulation. Copyright © 2016 Elsevier Ltd. All rights reserved.

  2. Formation and collapse of internal transport barrier

    International Nuclear Information System (INIS)

    Fukuyama, A.; Itoh, K.; Itoh, S.-I.; Yagi, M.

    2001-01-01

    A theoretical model of internal transport barrier (ITB) is developed. The transport model based on the self-sustained turbulence theory of the current-diffusive ballooning mode is extended to include the effects of ExB rotation shear. Delayed formation of ITB is observed in transport simulations. The influence of finite gyroradius is also discussed. Simulation of the current ramp-up experiment successfully described the radial profile of density, temperature and safety factor. A model of ITB collapse due to magnetic braiding is proposed. Sudden enhancement of transport triggered by overlaping of magnetic islands terminates ITB. The possibility of destabilizing global low-n modes is also discussed. (author)

  3. Theory of anomalous transport in toroidal helical plasmas

    International Nuclear Information System (INIS)

    Itoh, K.; Itoh, S.; Fukuyama, A.

    1992-03-01

    Theoretical model of the anomalous transport in Torsatron/Heliotron plasmas is developed, based on the current-diffusive interchange instability which is destabilized due to the averaged magnetic hill near edge. Analytic formula of transport coefficient is derived. This model explains the high edge transport, the power degradation and energy confinement scaling law and the enhanced heat-pulse thermal conduction. (author)

  4. Performativity and the project: enacting urban transport security in Europe

    NARCIS (Netherlands)

    Hoijtink, M.

    2015-01-01

    In April 2011, a large consortium of European rail and security suppliers, transport operators and research organisations launched the Secured Urban Transportation - European Demonstration (SECUR-ED) project with the objective of providing public transport operators with the means to enhance urban

  5. On radio frequency wave induced radial transport and wave helicity

    International Nuclear Information System (INIS)

    Petrzilka, V.

    1992-09-01

    Expressions for wave induced radial transport are derived allowing simple estimates. The transport is enhanced due to the presence of poloidal magnetostatic field and in the vicinity of the ion cyclotron resonance. The direction of the wave induced transport depends also on the wave polarization. (author) 19 refs

  6. Chemical transport reactions

    CERN Document Server

    Schäfer, Harald

    2013-01-01

    Chemical Transport Reactions focuses on the processes and reactions involved in the transport of solid or liquid substances to form vapor phase reaction products. The publication first offers information on experimental and theoretical principles and the transport of solid substances and its special applications. Discussions focus on calculation of the transport effect of heterogeneous equilibria for a gas motion between equilibrium spaces; transport effect and the thermodynamic quantities of the transport reaction; separation and purification of substances by means of material transport; and

  7. Beam transport

    International Nuclear Information System (INIS)

    1988-01-01

    Considerable experience has now been gained with the various beam transport lines, and a number of minor changes have been made to improve the ease of operation. These include: replacement of certain little-used slits by profile monitors (harps or scanners); relocation of steering magnets, closer to diagnostic harps or profile scanners; installation of a scanner inside the isocentric neutron therapy system; and conversion of a 2-doublet quadrupole telescope (on the neutron therapy beamline) to a 2-triplet telescope. The beam-swinger project has been delayed by very late delivery of the magnet iron to the manufacturer, but is now progressing smoothly. The K=600 spectrometer magnets have now been delivered and are being assembled for field mapping. The x,y-table with its associated mapping equipment is complete, together with the driver software. One of the experimental areas has been dedicated to the production of collimated neutron beams and has been equipped with a bending magnet and beam dump, together with steel collimators fixed at 4 degrees intervals from 0 degrees to 16 degrees. Changes to the target cooling and shielding system for isotope production have led to a request for much smaller beam spot sizes on target, and preparations have been made for rearrangement of the isotope beamline to permit installation of quadrupole triplets on the three beamlines after the switching magnet. A practical system of quadrupoles for matching beam properties to the spectrometer has been designed. 6 figs

  8. Tip enhancement

    CERN Document Server

    Kawata, Satoshi

    2007-01-01

    This book discusses the recent advances in the area of near-field Raman scattering, mainly focusing on tip-enhanced and surface-enhanced Raman scattering. Some of the key features covered here are the optical structuring and manipulations, single molecule sensitivity, analysis of single-walled carbon nanotubes, and analytic applications in chemistry, biology and material sciences. This book also discusses the plasmonic materials for better enhancement, and optical antennas. Further, near-field microscopy based on second harmonic generation is also discussed. Chapters have been written by some of the leading scientists in this field, who present some of their recent work in this field.·Near-field Raman scattering·Tip-enhanced Raman spectroscopy·Surface-enhanced Raman spectroscopy·Nano-photonics·Nanoanalysis of Physical, chemical and biological materials beyond the diffraction limits·Single molecule detection

  9. Magnon transport through microwave pumping

    OpenAIRE

    Nakata Kouki; Simon Pascal; Loss Daniel

    2015-01-01

    We present a microscopic theory of magnon transport in ferromagnetic insulators (FIs). Using magnon injection through microwave pumping, we propose a way to generate magnon dc currents and show how to enhance their amplitudes in hybrid ferromagnetic insulating junctions. To this end focusing on a single FI, we first revisit microwave pumping at finite (room) temperature from the microscopic viewpoint of magnon injection. Next, we apply it to two kinds of hybrid ferromagnetic insulating juncti...

  10. Plant Transporter Identification

    DEFF Research Database (Denmark)

    Larsen, Bo

    Membrane transport proteins (transporters) play a critical role for numerous biological processes, by controlling the movements of ions and molecules in and out of cells. In plants, transporters thus function as gatekeepers between the plant and its surrounding environment and between organs......, tissues, cells and intracellular compartments. Since plants are highly compartmentalized organisms with complex transportation infrastructures, they consequently have many transporters. However, the vast majority of predicted transporters have not yet been experimentally verified to have transport...... activity. This project contains a review of the implemented methods, which have led to plant transporter identification, and present our progress on creating a high-throughput functional genomics transporter identification platform....

  11. Glucose transport in brain - effect of inflammation.

    Science.gov (United States)

    Jurcovicova, J

    2014-01-01

    membrane to transport glucose into cells, and GLUT8 from cytosol to rough endoplasmic reticulum to recover redundant glucose to cytosol after protein glycosylation. In autoimmune diseases, the enhanced glucose uptake was found in inflamed peripheral tissue, mainly due to proliferating fibroblasts and activated macrophages. In our experimental model of rheumatoid arthritis (adjuvant arthritis), enhanced 2-deoxy-2[F-18]fluoro-D-glucose was found in the hippocampus and amygdala two days after the induction of the disease which, similarly as in the peripheral joints, can be ascribed to the activated macrophages. The knowledge on the glucose transport and the role of glucose transporters in the brain during systemic autoimmune inflammation is still incomplete and needs further investigations.

  12. Analysis of colloid transport

    International Nuclear Information System (INIS)

    Travis, B.J.; Nuttall, H.E.

    1985-01-01

    The population balance methodology is described and applied to the transport and capture of polydispersed colloids in packed columns. The transient model includes particle growth, capture, convective transport, and dispersion. We also follow the dynamic accumulation of captured colloids on the solids. The multidimensional parabolic partial differential equation was solved by a recently enhanced method of characteristics technique. This computational technique minimized numerical dispersion and is computationally very fast. The FORTRAN 77 code ran on a VAX-780 in less than a minute and also runs on an IBM-AT using the Professional FORTRAN compiler. The code was extensively tested against various simplified cases and against analytical models. The packed column experiments by Saltelli et al. were re-analyzed incorporating the experimentally reported size distribution of the colloid feed material. Colloid capture was modeled using a linear size dependent filtration function. The effects of a colloid size dependent filtration factor and various initial colloid size distributions on colloid migration and capture were investigated. Also, we followed the changing colloid size distribution as a function of position in the column. Some simple arguments are made to assess the likelihood of colloid migration at a potential NTS Yucca Mountain waste disposal site. 10 refs., 3 figs., 1 tab

  13. Transport of Radioactive Materials

    International Nuclear Information System (INIS)

    2001-01-01

    This address overviews the following aspects: concepts on transport of radioactive materials, quantities used to limit the transport, packages, types of packages, labeling, index transport calculation, tags, labeling, vehicle's requirements and documents required to authorize transportation. These requirements are considered in the regulation of transport of radioactive material that is in drafting step

  14. Transportation and the environment.

    NARCIS (Netherlands)

    Banister, D.; Anderton, K.; Bonilla, D.; Givoni, M.; Schwanen, T.

    2011-01-01

    The growth of CO2-intensive transport, mobility and the impact of transport on the environment are reviewed. The recent global exponential growth in transport is unsustainable and must end unless the transport sector can decarbonize. The paper examines solutions for low-carbon transport systems; the

  15. The FORATOM Transport Working Group

    International Nuclear Information System (INIS)

    Lehmann, P.

    2000-01-01

    35% of the electricity in western Europe is taking on growing importance at a time when it is becoming clear that nuclear power has definite advantages in terms of economics, security of supply and environment protection. The prospect of new countries joining the European Union in the foreseeable future is also enhancing these concerns. Transport is an essential link in the nuclear industry and safe transport of radioactive material is a major issue because any disruption of transport has serious consequences for the management of the power generation. The challenges are double, on the one hand to maintain the economic and safe operation of nuclear transport, on the other to ensure that the community and its leaders fully appreciate the contribution of the industry in this field. Both are part of the tasks of the FORATOM Transport Working Group. (author)

  16. Biocatalyst Enhancement

    Science.gov (United States)

    The increasing availability of enzyme collections has assisted attempts by pharmaceutical producers to adopt green chemistry approaches to manufacturing. A joint effort between an enzyme producer and a pharmaceutical manufacturer has been enhanced over the past three years by ena...

  17. Andreev levels in a single-channel conductor

    DEFF Research Database (Denmark)

    Titov, M.; Mortensen, Asger; Schomerus, H.

    2001-01-01

    We calculate the subgap density of states of a disordered single-channel normal metal connected to a superconductor at one end (normal-metal-superconductor junction) or at both ends [superconductor-normal-metal-superconductor (SNS) junction]. The probability distribution of the energy of a bound ...

  18. Observation of conductance doubling in an Andreev quantum point contact

    Science.gov (United States)

    Kjaergaard, M.; Nichele, F.; Suominen, H.; Nowak, M.; Wimmer, M.; Akhmerov, A.; Folk, J.; Flensberg, K.; Shabani, J.; Palmstrom, C.; Marcus, C.

    One route to study the non-Abelian nature of excitations in topological superconductors is to realise gateable two dimensional (2D) semiconducting systems, with spin-orbit coupling in proximity to an s-wave superconductor. Previous work on coupling 2D electron gases (2DEG) with superconductors has been hindered by a non-ideal interface and unstable gateability. We report measurements on a gateable 2DEG coupled to superconductors through a pristine interface, and use aluminum grown in situ epitaxially on an InGaAs/InAs electron gas. We demonstrate quantization in units of 4e2 / h in a quantum point contact (QPC) in such hybrid systems. Operating the QPC as a tunnel probe, we observe a hard superconducting gap, overcoming the soft-gap problem in 2D superconductor/semiconductor systems. Our work paves way for a new and highly scalable system in which to pursue topological quantum information processing. Research supported by Microsoft Project Q and the Danish National Research Foundation.

  19. Advanced Transportation Institute 2008.

    Science.gov (United States)

    2009-02-01

    The seventh version of the Advanced Transportation Institute (ATI-08) was conducted in 2008 to encourage high school students to pursue careers in the field of transportation engineering. The University Transportation Center for Alabama partnered wit...

  20. Advanced Transportation Institute 2009.

    Science.gov (United States)

    2009-09-01

    The eighth version of the Advanced Transportation Institute (ATI-09) was conducted in 2009 to encourage high school students to pursue careers in the field of transportation engineering. The University Transportation Center for Alabama partnered with...

  1. Innovative Technologies in Transportation

    Science.gov (United States)

    2004-12-01

    An historical overview of the transportation infrastructure of the United States and Texas is provided. Data for trends in transportation is analyzed and projections for the future are postulated. A survey of current technologies in transportation is...

  2. State Transportation Statistics 2010

    Science.gov (United States)

    2011-09-14

    The Bureau of Transportation Statistics (BTS), a part of DOTs Research and Innovative Technology Administration (RITA), presents State Transportation Statistics 2010, a statistical profile of transportation in the 50 states and the District of Col...

  3. State transportation statistics 2009

    Science.gov (United States)

    2009-01-01

    The Bureau of Transportation Statistics (BTS), a part of DOTs Research and : Innovative Technology Administration (RITA), presents State Transportation : Statistics 2009, a statistical profile of transportation in the 50 states and the : District ...

  4. State Transportation Statistics 2011

    Science.gov (United States)

    2012-08-08

    The Bureau of Transportation Statistics (BTS), a part of DOTs Research and Innovative Technology Administration (RITA), presents State Transportation Statistics 2011, a statistical profile of transportation in the 50 states and the District of Col...

  5. State Transportation Statistics 2013

    Science.gov (United States)

    2014-09-19

    The Bureau of Transportation Statistics (BTS), a part of the U.S. Department of Transportations (USDOT) Research and Innovative Technology Administration (RITA), presents State Transportation Statistics 2013, a statistical profile of transportatio...

  6. Overview of TFTR transport studies

    International Nuclear Information System (INIS)

    Hawryluk, R.J.; Arunasalam, V.; Beer, M.; Bell, M.; Bell, R.; Biglari, H.; Bitter, M.; Boivin, R.; Bretz, N.L.; Budny, R.; Cheng, C.Z.; Chu, T.K.; Cohen, S.A.; Cowley, S.; Efthimion, P.C.; Fredrickson, E.; Furth, H.P.; Goldston, R.J.; Greene, G.; Grek, B.; Grisham, L.R.; Hammett, G.; Hill, K.W.; Hosea, J.; Hulse, R.A.; Hsuan, H.; Janos, A.; Jassby, D.; Jobes, F.C.; Johnson, D.W.; Johnson, L.C.; Kieras-Phillips, C.; Kilpatrick, S.J.; Kugel, H.; La Marche, P.H.; LeBlanc, B.; Manos, D.M.; Mansfield, D.K.; Mazzucato, E.; McCarthy, M.P.; McCune, D.C.; McGuire, K.M.; Meade, D.M.; Medley, S.S.; Mikkelsen, D.R.; Monticello, D.; Motley, R.; Mueller, D.; Nazikian, R.; Owens, D.K.; Park, H.; Park, W.; Paul, S.; Perkins, F.; Ramsey, A.T.; Redi, M.H.; Rewoldt, G.; Roquemore, A.L.; Rutherford, P.H.; Schilling, G.; Schivell, J.; Schmidt, G.L.; Scott, S.D.; Stevens, J.; Stratton, B.C.; Stodiek, W.; Synakowski, E.; Tang, W.; Taylor, G.; Timberlake, J.R.; Towner, H.H.; Ulrickson, M.; von Goeler, S.; Wieland, R.; Williams, M.; Wilson, J.R.; Wong, K.L.; Yamada, M.; Yoshikawa, S.; Young, K.M.; Zarnstorff, M.C.; Zweben, S.J.; Bush, C.E.; Fonck, R.J; Roberts, D.; Heidbrink, W.; Kesner, J.; Marmar, E.S.; Snipes, J.; Takase, Y.; Terry, J.; Mauel, M.; Navratil, G.A.; Sabbagh, S.; Nagayama, Y.; Pitcher, S.

    1991-10-01

    A review of TFTR plasma transport studies is presented. Parallel transport and the confinement of suprathermal ions are found to be relatively well described by theory. Cross-field transport of the thermal plasma, however, is anomalous with the momentum diffusivity being comparable to the ion thermal diffusivity and larger than the electron thermal diffusivity in neutral beam heated discharges. Perturbative experiments have studied non-linear dependencies in the transport coefficients and examined the role of possible non-local phenomena. The underlying turbulence has been studied using microwave scattering, beam emission spectroscopy and microwave reflectometry over a much broader range in k perpendicular than previously possible. Results indicate the existence of large-wavelength fluctuations correlated with enhanced transport. MHD instabilities set important operational constraints. However, by modifying the current profile using current ramp-down techniques, it has been possible to extend the operating regime to higher values of both var-epsilon β p and normalized β T . In addition, the interaction of MHD fluctuations with fast ions, of potential relevance to α-particle confinement in D-T plasmas, has been investigated. The installation of carbon-carbon composite tiles and improvements in wall conditioning, in particular the use of Li pellet injection to reduce the carbon recycling, continue to be important in the improvement of plasma performance. 96 refs., 16 figs

  7. Smart Growth and Transportation

    Science.gov (United States)

    Describes the relationship between smart growth and transportation, focusing smart and sustainable street design, transit-oriented development, parking management, sustainable transportation planning, and related resources.

  8. Neoclassical transport in NCSX

    International Nuclear Information System (INIS)

    Mikkelsen, D.R.; Zarnstorff, M.C.; Beidler, C.D.; Maassberg, H.; Houlberg, W.A.; Spong, D.A.; Tribaldos, V.

    2003-01-01

    Methods for calculating neoclassical transport in the National Compact Stellarator Experiment (NCSX) are discussed, with particular attention to developing computationally inexpensive predictions of neoclassical transport. (orig.)

  9. Journal of transportation engineering

    National Research Council Canada - National Science Library

    1983-01-01

    The Journal of Transportation Engineering contains technical and professional articles on the planning, design, construction, maintenance, and operation of air, highway, rail, and urban transportation...

  10. Transportation Industry 2004

    National Research Council Canada - National Science Library

    Miller, Evan; Kathir, Nathan; Brogan, Dennis M

    2004-01-01

    .... Because the defense sector relies on commercial transportation for both peacetime activities and for power projection, senior military leaders must understand the global transportation industry...

  11. Saxton Transportation Operations Laboratory

    Data.gov (United States)

    Federal Laboratory Consortium — The Saxton Transportation Operations Laboratory (Saxton Laboratory) is a state-of-the-art facility for conducting transportation operations research. The laboratory...

  12. Hopping Conductivity Enhanced by Microwave Radiation

    International Nuclear Information System (INIS)

    Ovadyahu, Z

    2012-01-01

    Hopping conductivity is enhanced when exposed to microwave (MW) fields. Data taken on several Anderson-localized systems and granular-aluminium are presented to illustrate the generality of the phenomenon. It is suggested that the effect is due to a field-enhanced hopping, which is the ac version of a non-ohmic effect familiar from studies in the dc transport regime.

  13. Public transport optimisation emphasising passengers’ travel behaviour.

    OpenAIRE

    Jensen, Jens Parbo; Nielsen, Otto Anker; Prato, Carlo Giacomo

    2015-01-01

    Passengers in public transport complaining about their travel experiences are not uncommon. This might seem counterintuitive since several operators worldwide are presenting better key performance indicators year by year. The present PhD study focuses on developing optimisation algorithms to enhance the operations of public transport while explicitly emphasising passengers’ travel behaviour and preferences. Similar to economic theory, interactions between supply and demand are omnipresent in ...

  14. Urban Transportation: Issue and Solution

    Directory of Open Access Journals (Sweden)

    Haryati Shafii

    2011-10-01

    Full Text Available Generally, quality of life of urban population is heavily dependent on social facilities provided within the environment. One of the most important facilities is transportations. Study on transportation mode in an urban area is especially very important because for almost every individual living in a large and densely populated area, mobility is one of the most crucial issues in everyday life. Enhance mobility, faster journey to work and less pollution from petrol-propelled vehicles can increase the quality of life, which in turn lead to a sustainable urban living. The study present transportation mode usage issues faced by community related to quality of life in an urban area. This study identifies several issues of transportation mode in urban areas and its impact on the quality of life. The study areas are Putrajaya, Kuala Lumpur and Bandar Kajang, Selangor. The methodology used in this research is secondary and primary data. The questionnaires for the survey were distributed from May 2008 to Jun 2008. These researches were conducted on 144 respondents for to evaluate their perception of transportation mode correlated to the quality of life. The collected data were then analyzed using “Statistical Packages for the Social Science” (SPSS. The respondents comprise of 61 males and 84 females from the age group of 18 to 57 years. This study identifies the percentage of public transportation mode usage in urban area, such as buses (16.7%, train (ERL, monorail and commuter-6.4%; which is very low compared to owning personal car (45.8% and motorcycle (25.4%.The result shows owning personal car is the highest (45.8% in three study areas and monorail and taxi are the lowest (1.4%. The Chi Square Test shows that among the mode transportation with traffic jam is quite difference in Kuala Lumpur, Putrajaya and Kajang. Analysis of the Chi Square Test shows the result is 0.000 (two sides to respondent answering “yes” and analysis of Spearman

  15. Carbon dioxide efficiency of terrestrial enhanced weathering

    OpenAIRE

    Moosdorf, Nils; Renforth, Philip; Hartmann, Jens

    2014-01-01

    Terrestrial enhanced weathering, the spreading of ultramafic silicate rock flour to enhance natural weathering rates, has been suggested as part of a strategy to reduce global atmospheric CO2 levels. We budget potential CO2 sequestration against associated CO2 emissions to assess the net CO2 removal of terrestrial enhanced weathering. We combine global spatial data sets of potential source rocks, transport networks, and application areas with associated CO2 emissions in optimistic and pessimi...

  16. Public transport optimisation emphasising passengers’ travel behaviour

    DEFF Research Database (Denmark)

    Jensen, Jens Parbo

    to the case where the two problems are solved sequentially without taking into account interdependencies. Figure 1 - Planning public transport The PhD study develops a metaheuristic algorithm to adapt the line plan configuration in order better to match passengers’ travel demand in terms of transfers as well......Passengers in public transport complaining about their travel experiences are not uncommon. This might seem counterintuitive since several operators worldwide are presenting better key performance indicators year by year. The present PhD study focuses on developing optimisation algorithms...... to enhance the operations of public transport while explicitly emphasising passengers’ travel behaviour and preferences. Similar to economic theory, interactions between supply and demand are omnipresent in the context of public transport operations. In public transport, the demand is represented...

  17. Speech enhancement

    CERN Document Server

    Benesty, Jacob; Chen, Jingdong

    2006-01-01

    We live in a noisy world! In all applications (telecommunications, hands-free communications, recording, human-machine interfaces, etc.) that require at least one microphone, the signal of interest is usually contaminated by noise and reverberation. As a result, the microphone signal has to be ""cleaned"" with digital signal processing tools before it is played out, transmitted, or stored.This book is about speech enhancement. Different well-known and state-of-the-art methods for noise reduction, with one or multiple microphones, are discussed. By speech enhancement, we mean not only noise red

  18. Modelling freight transport

    NARCIS (Netherlands)

    Tavasszy, L.A.; Jong, G. de

    2014-01-01

    Freight Transport Modelling is a unique new reference book that provides insight into the state-of-the-art of freight modelling. Focusing on models used to support public transport policy analysis, Freight Transport Modelling systematically introduces the latest freight transport modelling

  19. Transport of radioactive materials

    International Nuclear Information System (INIS)

    2013-01-01

    This ninth chapter presents de CNEN-NE--5.01 norm 'Transport of radioactive material'; the specifications of the radioactive materials for transport; the tests of the packages; the requests for controlling the transport and the responsibilities during the transport of radioactive material

  20. A transport synthetic acceleration method for transport iterations

    International Nuclear Information System (INIS)

    Ramone, G.L.; Adams, M.L.

    1997-01-01

    A family of transport synthetic acceleration (TSA) methods for iteratively solving within group scattering problems is presented. A single iteration in these schemes consists of a transport sweep followed by a low-order calculation, which itself is a simplified transport problem. The method for isotropic-scattering problems in X-Y geometry is described. The Fourier analysis of a model problem for equations with no spatial discretization shows that a previously proposed TSA method is unstable in two dimensions but that the modifications make it stable and rapidly convergent. The same procedure for discretized transport equations, using the step characteristic and two bilinear discontinuous methods, shows that discretization enhances TSA performance. A conjugate gradient algorithm for the low-order problem is described, a crude quadrature set for the low-order problem is proposed, and the number of low-order iterations per high-order sweep is limited to a relatively small value. These features lead to simple and efficient improvements to the method. TSA is tested on a series of problems, and a set of parameters is proposed for which the method behaves especially well. TSA achieves a substantial reduction in computational cost over source iteration, regardless of discretization parameters or material properties, and this reduction increases with the difficulty of the problem

  1. Development and teaching of a graduate course in multimodal transportation safety and risk.

    Science.gov (United States)

    2014-03-01

    One of the U.S. Department of Transportation (DOT)s strategic goals is to enhance public health and : safety by working toward the elimination of transportation-related deaths and injuries. Near term : targets include reducing highway fatalities, ...

  2. It's about time : investing in transportation to keep Texas economically competitive.

    Science.gov (United States)

    2011-03-01

    This current report, It's About Time: Investing in Transportation to Keep Texas : Economically Competitive, updates the February 2009 report by providing : an enhanced analysis of the current state of the Texas transportation system, : determining th...

  3. Dynamic transport study of the plasmas with transport improvement in LHD and JT-60U

    International Nuclear Information System (INIS)

    Ida, K.; Inagaki, S.; Sakamoto, R.; Tanaka, K.; Funaba, H.; Kubo, S.; Yoshinuma, M.; Shimozuma, T.; Takeiri, Y.; Ikeda, K.; Michael, C.; Tokuzawa, T.; Sakamoto, Yoshiteru; Takenaga, Hidenobu; Isayama, Akihiko; Ide, Shunsuke; Fujita, Takaaki

    2006-10-01

    A transport analysis during the transient phase of heating (a dynamic transport study) applied to the plasma with internal transport barriers (ITBs) in the Large Helical Device (LHD) heliotron and JT-60U tokamak is described. In the dynamic transport study 1) a slow transition between two transport branches is observed, 2) the time of the transition from the L-mode plasma to the ITB plasma is clearly determined by the onset of the flattening of the temperature profile in the core region and 3) a spontaneous phase transition from a weak, wide ITB to a strong, narrow ITB and its back-transition are observed. The flattening of the core region of the ITB transition and the back-transition between a wide ITB and a narrow ITB suggest the strong interaction of turbulent transport in space, where turbulence suppression at certain locations in the plasma causes the enhancement of turbulence and thermal diffusivity nearby. (author)

  4. TRANSPORTATION RESEARCH CONTRIBUTIONS TO SOCIETY BY UNIVERSITY TRANSPORTATION CENTERS

    Directory of Open Access Journals (Sweden)

    Robert C. JOHNS

    2003-01-01

    Full Text Available This paper discusses the importance of knowledge in the global economy and reviews the process in which knowledge is applied to develop innovations. It confirms the importance of innovation as a key factor for success in today's competitive environment. The paper discusses the contributions a university can make to the innovation process in the field of transportation, and offers a vision of how a university center can enhance and facilitate these contributions. It then describes the efforts of one center, including three examples of innovations facilitated by the center in traffic detection, regional planning, and pavement management. The paper concludes with suggestions that would strengthen the societal contributions of university transportation centers.

  5. Blood Sample Transportation by Pneumatic Transportation Systems

    DEFF Research Database (Denmark)

    Nybo, Mads; Lund, Merete E; Titlestad, Kjell

    2018-01-01

    BACKGROUND: Pneumatic transportation systems (PTSs) are increasingly used for transportation of blood samples to the core laboratory. Many studies have investigated the impact of these systems on different types of analyses, but to elucidate whether PTSs in general are safe for transportation...... analysis, and the hemolysis index). CONCLUSIONS: Owing to their high degree of heterogeneity, the retrieved studies were unable to supply evidence for the safety of using PTSs for blood sample transportation. In consequence, laboratories need to measure and document the actual acceleration forces...

  6. Magnetic type transportation system

    International Nuclear Information System (INIS)

    Kobama, Masao.

    1981-01-01

    Purpose: To enable automatic transportation of nuclear substances with optional setting for the transportation distance, even for a long distance, facilitating the automation of the transportation and decreasing the space for the installation of a direction converging section of the transporting path. Constitution: A transporting vehicle having a pair of permanent magnets or ferromagnetic bodies mounted with a predetermined gap to each other along the transporting direction is provided in the transporting path including a bent direction change section for transporting specimens such as nuclear materials, and a plurality of driving vehicles having permanent magnets or ferromagnetic bodies for magnetically attracting the transporting vehicle from outside of the transporting path are arranged to the outside of the transporting path. At least one of the driving vehicles is made to run along the transporting direction of the transporting path by a driving mechanism incorporating running section such as an endless chain to drive the transportation vehicle, and the transporting vehicle is successively driven by each of the driving mechanisms. (Kawakami, Y.)

  7. Transportation Emergency Preparedness Program (TEPP)

    International Nuclear Information System (INIS)

    1991-04-01

    The Transportation Emergency Preparedness Program (TEPP) will develop and enhance integrated emergency preparedness capabilities in two major areas. First, the program is responsible for planning and ensuring proper DOE response to transportation incidents involving DOE shipments. Second, the program is responsible for ensuring DOE can carry out its responsibilities under regulations, the National Contingency Plan (NCP) and the Federal Radiological Emergency Response Plan (FRERP) to provide technical advice and assistance as needed for any transportation incident involving radioactive or mixed hazard materials. This plan proposes a strategy for developing a comprehensive Transportation Emergency Preparedness Program, including a well organized central management and coordination structure, that serves as a process to identify, verify, and establish a consolidated effort across the Department in this very important area. This plan assumes Emergency Management to be the full range of emergency activities necessary for mitigation, preparedness, response and recovery while Emergency Preparedness activities are primarily those necessary in preparation for Incident Response Emergency Preparedness, which is the focus of this strategy plan, requires a well organized central coordination structure to be effective. 7 refs

  8. Transport in multiterminal graphene nanodevices.

    Science.gov (United States)

    Jayasekera, Thushari; Mintmire, J W

    2007-10-24

    We study the transport properties of multiterminal graphene nanodevices using the Landauer-Buttiker approach and the tight binding model. We consider a four-terminal device made at the crossing of a zigzag and armchair nanoribbons and two types of T-junction devices. The transport properties of graphene multiterminal devices are highly sensitive to the details of the junction region. Thus the properties are drastically different from those on the armchair and zigzag counterparts. In the cross-junction device, we see a conductance dip in the armchair lead associated with a conductance peak in the zigzag lead. We find that this effect is enhanced in a T-junction device with one armchair sidearm.

  9. Nitrogen transport during plasma-enhanced case nitriding of stainless steels - the effects of the passivating oxide layer; Stickstofftransport waehrend der plasmagestuetzten Randaufstickung nichtrostender Staehle - der Einfluss der passivierenden Oxidschicht

    Energy Technology Data Exchange (ETDEWEB)

    Parascandola, S.; Kruse, O.; Richter, E. [Forschungszentrum Rossendorf e.V. (FZR), Dresden (Germany). Inst. fuer Ionenstrahlphysik und Materialforschung; Moeller, W.

    1998-12-31

    Plasma-enhanced case nitriding at moderate temperatures is a promising technique for surface treatment of components made of stainless steels. In-situ ERD permits time-resolved and depth-dependent elemental analysis during the case nitriding process. This offers possibilities for process characterisation which are only briefly discussed in the paper. The oxide layer at the surface of the steel is a barrier to nitrogen input. In order to achieve fast nitrogen diffusion into the material, the oxide layer has to be largely removed in the low-energy ion implantation process. The observed equilibrium between diffusion and re-absorption is in good agreement with calculated as well as empirical results. (orig./CB) [Deutsch] Die plasmagestuetzte Randaufstickung bei moderaten Temperaturen ist eine erfolgversprechende Technologie zur Oberflaechenveredelung von Bauteilen aus nichtrostendem Stahl. Die Analytik mit in-situ ERD erlaubt zeit- und tiefenaufgeloeste Elementanalyse waehrend des Aufstickungsprozesses. Dadurch ergeben sich Moeglichkeiten der Prozesscharakterisierung, die hier nur angedeutet werden konnten. Die Oxidschicht an der Oberflaeche der nichtrostenden Staehle stellt eine Barriere fuer den Stickstoffeintrag dar. Fuer schnelle Stickstoffdiffusion muss die Oxidschicht bei der Niederenergie-Ionenimplantation weitgehend abgebaut werden. Das beobachtete Gleichgewicht zwischen Zerstaeubung und Wiederbelegung stimmt gut mit Simulationsrechnungen bzw. empirischen Werten ueberein. (orig.)

  10. Effect of grain boundary layer strain on the magnetic and transport properties of (100-x) La0.7Ca0.3MnO3/(x) BaTiO3 composites showing enhanced magnetoresistance

    International Nuclear Information System (INIS)

    Bose, Esa; Taran, S.; Karmakar, S.; Chaudhuri, B.K.; Pal, S.; Sun, C.P.; Yang, H.D.

    2007-01-01

    A ferromagnetic/ferroelectric composite system, viz. (100-x)La 0.7 Ca 0.3 MnO 3 [LCMO]/(x) BaTiO 3 [BTO] (with x=0.0%, 1.0%, 5.0%, 7.5%, 10.0% and 15.0%, in wt%) has been synthesized and the temperature-dependent DC magnetization M(T), resistivity ρ(T), magnetoresistance (MR), and thermoelectric power S(T) have been studied. Both metal-insulator transition temperature (T MI ) and the corresponding Curie temperature (T C ) decrease whereas peak resistivity at T MI increases as x is enhanced from 0.0% to 10.0%. For x>10.0%, this trend of variation is reversed. A maximum three-fold increase of magnetoresistance (MR) is observed (for sample with x=10.0%) due to the addition of ferroelectric (non-magnetic) perovskite BTO (compared to the mother compound LCMO). Interestingly, thermoelectric power S(T) shows a pronounced depression (dip) near the magnetic transition region for the composite samples. The above results have been analyzed considering strain induced by the LCMO/BTO grain boundary layer (BL)

  11. Intra-site Secure Transport Vehicle test and evaluation

    International Nuclear Information System (INIS)

    Scott, S.

    1995-01-01

    In the past many DOE and DoD facilities involved in handling nuclear material realized a need to enhance the safely and security for movement of sensitive materials within their facility, or ''intra-site''. There have been prior efforts to improve on-site transportation; however, there remains a requirement for enhanced on-site transportation at a number of facilities. The requirements for on-site transportation are driven by security, safety, and operational concerns. The Intra-site Secure Transport Vehicle (ISTV) was designed to address these concerns specifically for DOE site applications with a standardized vehicle design. This paper briefly reviews the ISTV design features providing significant enhancement of onsite transportation safety and security, and also describes the test and evaluation activities either complete of underway to validate the vehicle design and operation

  12. Transportation Technology: Rail Transport and Logistics

    Science.gov (United States)

    Lang, Aaron B.

    2011-01-01

    Transportation can simply be defined as the movement of goods, services, and people from one location to another. Without an efficient means to transport goods from place to place, the economy would be nothing like it is today. Throughout the history of the United States, American railroads have paved the way toward creating a nation of great…

  13. The serotonin transporter and early life stress : Translational perspectives

    NARCIS (Netherlands)

    Houwing, Danielle J; Buwalda, Bauke; Zee, van der Eddy; de Boer, Sietse F; Olivier, Jocelien D A

    2017-01-01

    The interaction between the serotonin transporter (SERT) linked polymorphic region (5-HTTLPR) and adverse early life stressing (ELS) events is associated with enhanced stress susceptibility and risk to develop mental disorders like major depression, anxiety, and aggressiveness. In particular, human

  14. Information disclosure on transport

    International Nuclear Information System (INIS)

    Kubo, M.

    1998-01-01

    In Japan, the transport of nuclear fuel materials strictly meets the above international convention and domestic regulations as well. Information on the transport of nuclear fuel materials within the country and between the country and foreign countries is treated carefully. Nuclear fuel materials are categorized for transport and are physically protected accordingly. Certain transportation information is treated with special precautions, including prior arrangements among sender, recipient and carrier, and prior agreement between entities subject to the jurisdiction and regulation of supplier and recipient countries. In the case of international transport, this information includes specifying time, place and procedures for transferring transport and responsibility. (O.M.)

  15. Secure Transportation Management

    International Nuclear Information System (INIS)

    Gibbs, P. W.

    2014-01-01

    Secure Transport Management Course (STMC) course provides managers with information related to procedures and equipment used to successfully transport special nuclear material. This workshop outlines these procedures and reinforces the information presented with the aid of numerous practical examples. The course focuses on understanding the regulatory framework for secure transportation of special nuclear materials, identifying the insider and outsider threat(s) to secure transportation, organization of a secure transportation unit, management and supervision of secure transportation units, equipment and facilities required, training and qualification needed.

  16. Monte Carlo Transport for Electron Thermal Transport

    Science.gov (United States)

    Chenhall, Jeffrey; Cao, Duc; Moses, Gregory

    2015-11-01

    The iSNB (implicit Schurtz Nicolai Busquet multigroup electron thermal transport method of Cao et al. is adapted into a Monte Carlo transport method in order to better model the effects of non-local behavior. The end goal is a hybrid transport-diffusion method that combines Monte Carlo Transport with a discrete diffusion Monte Carlo (DDMC). The hybrid method will combine the efficiency of a diffusion method in short mean free path regions with the accuracy of a transport method in long mean free path regions. The Monte Carlo nature of the approach allows the algorithm to be massively parallelized. Work to date on the method will be presented. This work was supported by Sandia National Laboratory - Albuquerque and the University of Rochester Laboratory for Laser Energetics.

  17. Methods of making transportation fuel

    Science.gov (United States)

    Roes, Augustinus Wilhelmus Maria [Houston, TX; Mo, Weijian [Sugar Land, TX; Muylle, Michel Serge Marie [Houston, TX; Mandema, Remco Hugo [Houston, TX; Nair, Vijay [Katy, TX

    2012-04-10

    A method for producing alkylated hydrocarbons is disclosed. Formation fluid is produced from a subsurface in situ heat treatment process. The formation fluid is separated to produce a liquid stream and a first gas stream. The first gas stream includes olefins. The liquid stream is fractionated to produce at least a second gas stream including hydrocarbons having a carbon number of at least 3. The first gas stream and the second gas stream are introduced into an alkylation unit to produce alkylated hydrocarbons. At least a portion of the olefins in the first gas stream enhance alkylation. The alkylated hydrocarbons may be blended with one or more components to produce transportation fuel.

  18. Magnetothermoelectric transport properties in phosphorene

    Science.gov (United States)

    Ma, R.; Liu, S. W.; Deng, M. X.; Sheng, L.; Xing, D. Y.; Sheng, D. N.

    2018-02-01

    We numerically study the electrical and thermoelectric transport properties in phosphorene in the presence of both a magnetic field and disorder. The quantized Hall conductivity is similar to that of a conventional two-dimensional electron gas, but the positions of all the Hall plateaus shift to the left due to the spectral asymmetry, in agreement with the experimental observations. The thermoelectric conductivity and Nernst signal exhibit remarkable anisotropy, and the thermopower is nearly isotropic. When a bias voltage is applied between top and bottom layers of phosphorene, both thermopower and Nernst signal are enhanced and their peak values become large.

  19. Performance measurement in transport sector analysis

    Directory of Open Access Journals (Sweden)

    M. Išoraitė

    2004-06-01

    Full Text Available The article analyses the following issues: 1. Performance measurement in literature. The performance measurement has an important role to play in the efficient and effective management of organizations. Kaplan and Johnson highlighted the failure of the financial measures to reflect changes in the competitive circumstances and strategies of modern organizations. Many authors have focused attention on how organizations can design more appropriate measurement systems. Based on literature, consultancy experience and action research, numerous processes have been developed that organizations can follow in order to design and implement systems. Many frameworks have been proposed that support these processes. The objective of such frameworks is to help organizations define a set of measures that reflect their objectives and assess their performance appropriately. 2. Transport sector performance and its impacts measuring. The purpose of transport measurement is to identify opportunities enhancing transport performance. Successful transport sector management requires a system to analyze its efficiency and effectiveness as well as plan interventions if transport sector performance needs improvement. Transport impacts must be measurable and monitorable so that the person responsible for the project intervention can decide when and how to influence them. Performance indicators provide a means to measure and monitor impacts. These indicators essentially reflect quantitative and qualitative aspects of impacts at given time and places. 3. Transport sector output and input. Transport sector inputs are the resources required to deliver transport sector outputs. Transport sector inputs are typically: human resources, particularly skilled resources (including specialists consulting inputs; technology processes such as equipment and work; and finance, both public and private. 4. Transport sector policy and institutional framework; 5. Cause – effect linkages; 6

  20. Turbulent transport of energetic ions

    International Nuclear Information System (INIS)

    Dannert, Tilman; Hauff, Thilo; Jenko, Frank; Guenter, Sibylle

    2006-01-01

    Approaching ITER operation, the issue of anomalous transport of fast particles becomes more and more important. This is partly because the ITER heating and current drive system relies heavily on neutral beam injection. Moreover burning plasmas are heated by fast fusion α particles.Fusion α particles are characterised by a fixed energy and an isotropic velocity distribution. Therefore they have gyroradii one magnitude larger than the thermal ions. The dependency of the particle diffusion of α test particles on the Kubo number K = VExBτc/λc (VExB mean E x B velocity, τc, λc correlation time and length of the turbulent potential) is presented. For different turbulent regimes, different dependency of the diffusion on the gyroradius is found. For large Kubo numbers, the transport is found to remain constant for gyroradii up to the correlation length of the potential, whereas it is drastically reduced in the small Kubo number regime.In the second part, a model for beam ions injected along the equilibrium magnetic field is described. The beam ions are treated gyrokinetically in a self-consistent way with the equilibrium distribution function taken as a shifted Maxwellian. The implications of such a model for the Vlasov equation, the field equations, and the calculation of moments and fluxes are discussed. Linear and nonlinear results, obtained with the gyrokinetic flux tube code GENE show the existence of a new instability driven by fast beam ions. The instability has a maximum growth rate at perpendicular wave numbers of kyρs ∼ 0.15 and depends mainly on the beam velocity and the density gradient of the beam ions. This instability leads to a replacement of bulk ion particle transport by fast ion particle transport, connected to a strongly enhanced heat flux. In the presence of this instability, the turbulent particle and heat transport is dominated by fast ions