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Sample records for absorption electron transport

  1. Effective light absorption and absolute electron transport rates in the coral Pocillopora damicornis.

    PubMed

    Szabó, Milán; Wangpraseurt, Daniel; Tamburic, Bojan; Larkum, Anthony W D; Schreiber, Ulrich; Suggett, David J; Kühl, Michael; Ralph, Peter J

    2014-10-01

    Pulse Amplitude Modulation (PAM) fluorometry has been widely used to estimate the relative photosynthetic efficiency of corals. However, both the optical properties of intact corals as well as past technical constrains to PAM fluorometers have prevented calculations of the electron turnover rate of PSII. We used a new Multi-colour PAM (MC-PAM) in parallel with light microsensors to determine for the first time the wavelength-specific effective absorption cross-section of PSII photochemistry, σII(λ), and thus PAM-based absolute electron transport rates of the coral photosymbiont Symbiodinium both in culture and in hospite in the coral Pocillopora damicornis. In both cases, σII of Symbiodinium was highest in the blue spectral region and showed a progressive decrease towards red wavelengths. Absolute values for σII at 440 nm were up to 1.5-times higher in culture than in hospite. Scalar irradiance within the living coral tissue was reduced by 20% in the blue when compared to the incident downwelling irradiance. Absolute electron transport rates of P. damicornis at 440 nm revealed a maximum PSII turnover rate of ca. 250 electrons PSII(-1) s(-1), consistent with one PSII turnover for every 4 photons absorbed by PSII; this likely reflects the limiting steps in electron transfer between PSII and PSI. Our results show that optical properties of the coral host strongly affect light use efficiency of Symbiodinium. Therefore, relative electron transport rates do not reflect the productivity rates (or indeed how the photosynthesis-light response is parameterised). Here we provide a non-invasive approach to estimate absolute electron transport rates in corals.

  2. Time-resolved X-ray Absorption Spectroscopy for Electron Transport Study in Warm Dense Gold

    NASA Astrophysics Data System (ADS)

    Lee, Jong-Won; Bae, Leejin; Engelhorn, Kyle; Heimann, Philip; Ping, Yuan; Barbrel, Ben; Fernandez, Amalia; Beckwith, Martha Anne; Cho, Byoung-Ick; GIST Team; IBS Team; LBNL Collaboration; SLAC Collaboration; LLNL Collaboration

    2015-11-01

    The warm dense Matter represents states of which the temperature is comparable to Fermi energy and ions are strongly coupled. One of the experimental techniques to create such state in the laboratory condition is the isochoric heating of thin metal foil with femtosecond laser pulses. This concept largely relies on the ballistic transport of electrons near the Fermi-level, which were mainly studied for the metals in ambient conditions. However, they were barely investigated in warm dense conditions. We present a time-resolved x-ray absorption spectroscopy measured for the Au/Cu dual layered sample. The front Au layer was isochorically heated with a femtosecond laser pulse, and the x-ray absorption changes around L-edge of Cu, which was attached on the backside of Au, was measured with a picosecond resolution. Time delays between the heating of the `front surface' of Au layer and the alternation of x-ray spectrum of Cu attached on the `rear surface' of Au indicate the energetic electron transport mechanism through Au in the warm dense conditions. IBS (IBS-R012-D1) and the NRF (No. 2013R1A1A1007084) of Korea.

  3. Effect of electron collisions on transport coefficients induced by the inverse bremsstrahlung absorption in plasmas

    SciTech Connect

    Bendib, A.; Tahraoui, A.; Bendib, K.; Mohammed El Hadj, K.; Hueller, S.

    2005-03-01

    The transport coefficients of fully ionized plasmas under the influence of a high-frequency electric field are derived solving numerically the electron Fokker-Planck equation using a perturbation method, parametrized as a function of the electron mean-free-path {lambda}{sub ei} compared to the spatial scales L. The isotropic and anisotropic contributions of the inverse bremsstrahlung heating are considered. Electron-electron collision terms are kept in the analysis, which allows us to consider with sufficient accuracy to describe plasmas with arbitrary atomic number Z. Practical numerical fits of the transport coefficients are proposed as functions of Z and the collisionality parameter {lambda}{sub ei}/L.

  4. Ferrocene-Substituted Naphthalenediimide with Broad Absorption and Electron-Transport Properties in the Segregated-Stack Structure.

    PubMed

    Takai, Atsuro; Sakamaki, Daisuke; Seki, Shu; Matsushita, Yoshitaka; Takeuchi, Masayuki

    2016-05-23

    A new naphthalenediimide (NDI) molecule, where two ferrocene (Fc) units were directly attached to both imide nitrogens (Fc-NDI-Fc), was synthesized. The Fc units provide high crystallinity to Fc-NDI-Fc with good solubility to conventional organic solvents. The Fc units also work as electron-donating substituents, in contrast to the electron-deficient NDI unit, resulting in broad charge-transfer absorption of Fc-NDI-Fc from the UV region to 1500 nm in the solid state. The crystal structure analysis revealed that Fc-NDI-Fc formed a segregated-stack structure. The DFT calculation based on the crystal structure showed that the NDI π-orbitals extended over two axes. The extended π-network of the NDI units led to the electron-transport properties of Fc-NDI-Fc, which was confirmed using a flash-photolysis time-resolved microwave conductivity technique. PMID:27061109

  5. Lipids: Absorption and transport

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Due to the hydrophobic nature of lipids, dietary fat is handled differently than protein or carbohydrate with respect with digestion and absorption. Dietary fats are broken down throughout the gastrointestinal system. A unique group of enzymes and cofactors allows this process to proceed in an eff...

  6. The impact of cell-specific absorption properties on the correlation of electron transport rates measured by chlorophyll fluorescence and photosynthetic oxygen production in planktonic algae.

    PubMed

    Blache, Ulrich; Jakob, Torsten; Su, Wanwen; Wilhelm, Christian

    2011-08-01

    Photosynthesis-irradiance (P-E)-curves describe the photosynthetic performance of autotrophic organisms. From these P-E-curves the photosynthetic parameters α-slope, P(max), and E(k) can be deduced which are often used to characterize and to compare different organisms or organisms in acclimation to different environmental conditions. Particularly, for in situ-measurements of P-E curves of phytoplankton the analysis of variable chlorophyll fluorescence proved its potential as a sensitive and rapid method. By using Chlorella vulgaris (Trebouxiophyceae), Nannochloropsis salina (Eustigmatophyceae), Skeletonema costatum and Cyclotella meneghiniana (Bacillariophyceae), the present study investigated the influence of cellular bio-optical properties on the correlation of the photosynthetic parameters derived from fluorescence-based P-E-curves with photosynthetic parameters obtained from the measurement of oxygen evolution. It is demonstrated that small planktonic algae show a wide range of cellular absorptivity which was subject to species-specifity, growth stage and environmental conditions, e.g. nutrient limitation. This variability in bio-optical properties resulted in a great deviation of relative electron transport rates (rETRs) from oxygen-based photosynthesis rates. Thus, the photosynthetic parameters α-slope and P(max) derived from rETRs strongly depend on the specific cellular absorptivity and cannot be used to compare the photosynthetic performance of cells with different optical properties. However, it was shown that E(k) is independent of cellular absorptivity and could be used to compare samples with unknown optical properties. PMID:21571541

  7. The impact of cell-specific absorption properties on the correlation of electron transport rates measured by chlorophyll fluorescence and photosynthetic oxygen production in planktonic algae.

    PubMed

    Blache, Ulrich; Jakob, Torsten; Su, Wanwen; Wilhelm, Christian

    2011-08-01

    Photosynthesis-irradiance (P-E)-curves describe the photosynthetic performance of autotrophic organisms. From these P-E-curves the photosynthetic parameters α-slope, P(max), and E(k) can be deduced which are often used to characterize and to compare different organisms or organisms in acclimation to different environmental conditions. Particularly, for in situ-measurements of P-E curves of phytoplankton the analysis of variable chlorophyll fluorescence proved its potential as a sensitive and rapid method. By using Chlorella vulgaris (Trebouxiophyceae), Nannochloropsis salina (Eustigmatophyceae), Skeletonema costatum and Cyclotella meneghiniana (Bacillariophyceae), the present study investigated the influence of cellular bio-optical properties on the correlation of the photosynthetic parameters derived from fluorescence-based P-E-curves with photosynthetic parameters obtained from the measurement of oxygen evolution. It is demonstrated that small planktonic algae show a wide range of cellular absorptivity which was subject to species-specifity, growth stage and environmental conditions, e.g. nutrient limitation. This variability in bio-optical properties resulted in a great deviation of relative electron transport rates (rETRs) from oxygen-based photosynthesis rates. Thus, the photosynthetic parameters α-slope and P(max) derived from rETRs strongly depend on the specific cellular absorptivity and cannot be used to compare the photosynthetic performance of cells with different optical properties. However, it was shown that E(k) is independent of cellular absorptivity and could be used to compare samples with unknown optical properties.

  8. Biological Electron Transport Systems

    PubMed Central

    Cowan, Dwaine O.; Pasternak, Gavril; Kaufman, Frank

    1970-01-01

    The solid-state electrical conductivities of a number of ferredoxin model compounds are reported. For one of these compounds, (KFeS2)n, an electron transfer rate for a 25 Å unit is shown to be at least 1 × 108 electrons sec-1. The rate becomes proportionally larger for smaller molecular units. This rapid rate is consistant with a short pipe model for electron transport between two reaction sites. Some of the factors leading to this rapid transfer rate are considered. PMID:5269247

  9. Electronic transport in graphene

    NASA Astrophysics Data System (ADS)

    Zhang, Yuanbo

    This dissertation focuses on the electronic transport properties of graphene, a single atomic layer of graphite. Graphene is a novel two-dimensional system in which electron transport is effectively governed by the relativistic quantum theory. We discover a variety of new phenomenon which stem from the "relativistic" nature of the electron dynamics in graphene. An unusual quantum Hall (QH) effect is discovered in graphene at low temperatures and strong magnetic fields. Unlike conventional two-dimensional electron systems, in graphene the observed quantization condition is characterized by half integers rather than integers. Our investigation of the magneto-oscillations in resistance reveals a Berry's phase of pi associated with the electron motion in graphene. The half-integer quantization, as well as the Berry's phase, is attributed to the peculiar topology of the graphene band structure with a linear dispersion relation and vanishing mass near the Dirac point, which can be described by relativistic quantum electrodynamics. This is further confirmed by our measurement of the effective carrier mass, m*, which obeys Einstein's equation: E = m*c*2 where c* ≈ c/300 is the effective speed of light for electrons in graphene. The availability of high magnetic fields up to 45 Tesla allows us to study the magneto-transport in graphene in the extreme quantum limit. Under such condition, we discover new sets of QH states at filling factors nu = 0, +/-1, +/-4, indicating the lifting of the four-fold degeneracy of the previously observed QH states at nu = +/-4(|n|+1/2), where n is the Landau level index. In particular, the presence of the nu = 0, +/-1 QH states indicates that the Landau level at the charge neutral Dirac point splits into four sub-levels, lifting both sublattice and spin degeneracy, thereby potentially indicating a many-body correlation in this LL. The QH effect at nu = +/-4 is investigated in tilted magnetic fields and is attributed to lifting of the n

  10. Iron absorption and transport-an update.

    PubMed

    Conrad, M E; Umbreit, J N

    2000-08-01

    Iron is vital for all living organisms. However, excess iron is hazardous because it produces free radical formation. Therefore, iron absorption is carefully regulated to maintain an equilibrium between absorption and body loss of iron. In countries where heme is a significant part of the diet, most body iron is derived from dietary heme iron because heme binds few of the luminal intestinal iron chelators that inhibit absorption of non-heme iron. Uptake of luminal heme into enterocytes occurs as a metalloporphyrin. Intracellularly, iron is released from heme by heme oxygenase so that iron leaves the enterocyte to enter the plasma as non-heme iron. Ferric iron is absorbed via a beta(3) integrin and mobilferrin (IMP) pathway that is not shared with other nutritional metals. Ferrous iron uptake is facilitated by DMT-1 (Nramp-2, DCT-1) in a pathway shared with manganese. Other proteins were recently described which are believed to play a role in iron absorption. SFT (Stimulator of Iron Transport) is postulated to facilitate both ferric and ferrous iron uptake, and Hephaestin is thought to be important in transfer of iron from enterocytes into the plasma. The iron concentration within enterocytes reflects the total body iron and either upregulates or satiates iron-binding sites on regulatory proteins. Enterocytes of hemochromatotics are iron-depleted similarly to the absorptive cells of iron-deficient subjects. Iron depletion, hemolysis, and hypoxia each can stimulate iron absorption. In non-intestinal cells most iron uptake occurs via either the classical clathrin-coated pathway utilizing transferrin receptors or the poorly defined transferrin receptor independent pathway. Non-intestinal cells possess the IMP and DMT-1 pathways though their role in the absence of iron overload is unclear. This suggests that these pathways have intracellular functions in addition to facilitating iron uptake.

  11. Electron heating due to resonant absorption

    SciTech Connect

    Mizuno, K.; Spielman, R.B.; DeGroot, J.S.; Bollen, W.M.

    1980-01-01

    Intense, p-polarized microwaves (v/sub os//v/sub eo-/<1) are incident on an imhomogeneous plasma (10/sup 2/absorption near the critical surface (where the plasma frequency equals microwave frequency). Suprathermal electrons are heated by resonantly driven electrostatic field to produce a hot Maxwellian distribution. Most of the heated electrons flow towards the overdense region and are absorbed by the anode at the far end of the overdense region. At high power (v/sub os//v/sub eo-/>0.2), strong heating of thermal electrons, large amplitude ion acoustic turbulence, and a self-consistent dc electric field are observed near the critical surface. This dc electric field is enhanced by applying a weak magnetic field (..omega../sub ce//..omega../sub o/ approx. = 10/sup -2/).

  12. Methods development for electron transport

    NASA Astrophysics Data System (ADS)

    Ganapol, Barry D.

    1992-04-01

    This report consists of two code manuals and an article recently published in the proceedings of the American Nuclear Society Mathematics and Computation Topical Meeting held in Pittsburgh. In these presentations, deterministic calculational methods simulating electron transport in solids are detailed. The first method presented (Section 2) is for the solution of the Spencer-Lewis equation in which electron motion is characterized by continuous slowing down theory and a pathlength formulation. The FN solution to the standard monoenergetic transport equation for electron transport with isotropic scattering in finite media is given in Section 3. For both codes, complete flow charts, operational instructions and sample problems are included. Finally, in Section 4, an application of the multigroup formulation of electron transport in an infinite medium is used to verify an equivalent SN formulation. For this case, anisotropic scattering is also included.

  13. Regimes of suprathermal electron transport

    SciTech Connect

    Glinsky, M.E.

    1995-07-01

    Regimes of the one-dimensional (1-D) transport of suprathermal electrons into a cold background plasma are delineated. A well ordered temporal progression is found through eras where {ital J}{center_dot}{ital E} heating, hot electron--cold electron collisional heating, and diffusive heat flow dominate the cold electron energy equation. Scaling relations for how important quantities such as the width and temperature of the heated layer of cold electrons evolve with time are presented. These scaling relations are extracted from a simple 1-D model of the transport which can be written in dimensionless form with one free parameter. The parameter is shown to be the suprathermal electron velocity divided by the drift velocity of cold electrons which balances the suprathermal current. Special attention is paid to the assumptions which allow the reduction from the collisional Vlasov equation, using a Fokker--Planck collision operator, to this simple model. These model equations are numerically solved and compared to both the scaling relations and a more complete multigroup electron diffusion transport. Implications of the scaling relations on fast ion generation, magnetic field generation, and electric field inhibition of electron transport are examined as they apply to laser heated plasmas. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.

  14. Quasilinear analysis of absorption of ion Bernstein waves by electrons

    SciTech Connect

    Cardinali, A.; Paoletti, F.; Bernabei, S.; Ono, M.

    1995-01-01

    The effects induced on plasma electrons by an externally launched ion Bernstein wave (IBW), in the presence of a lower hybrid wave (LHW) in the current drive regime, are studied by analytical integration of the IBW ray-tracing equations along with the amplitude transport equation (Poynting theorem). The electric field amplitude parallel and perpendicular to the external magnetic field, the quasilinear diffusion coefficient, and the modified electron distribution function are analytically calculated in the case of IBW. The analytical calculation is compared to the numerical solution obtained by using a 2-D Fokker-Planck code for the distribution function, without any approximation for the collision operator. The synergy between the IBW and LHW can be accounted for, and the absorption of the IBW power when the electron distribution function presents a tail generated by the LHW in the current drive regime can be calculated.

  15. Quasilinear analysis of absorption of ion Bernstein waves by electrons

    SciTech Connect

    Cardinali, A.; Paoletti, F.; Bernabei, S.; Ono, M.

    1995-05-01

    The effects induced on plasma electrons by an externally launched ion Bernstein wave (IBW), in the presence of a lower hybrid wave (LHW) in the current drive regime, are studied by analytical integration of the IBW ray-tracing equations, along with the amplitude transport equation (Poynting theorem). The electric field amplitude parallel and perpendicular to the external magnetic field, the quasilinear diffusion coefficient, and the modified electron distribution function are analytically calculated in the case of IBW. The analytical calculation is compared to the numerical solution obtained by using a two-dimensional (2-D) Fokker--Planck code for the distribution function, without any approximation for the collision operator. The synergy between the IBW and LHW can be accounted for, and the absorption of the IBW power when the electron distribution function presents a tail generated by the LHW in the current drive regime can be calculated.

  16. Electron transport in bipyridinium films.

    PubMed

    Raymo, Françisco M; Alvarado, Robert J

    2004-01-01

    Bipyridinium dications are versatile building blocks for the assembly of functional materials. In particular, their reliable electrochemical response has encouraged the design of electroactive films. Diverse and elegant experimental strategies to coat metallic and semiconducting electrodes with bipyridinium compounds have, in fact, emerged over the past two decades. The resulting interfacial assemblies span from a few nanometers to several micrometers in thickness. They incorporate from a single molecular layer to large collections of entangled polymer chains. They transport electrons efficiently from the electrode surface to the film/solution interface and vice versa. Electron self-exchange between and the physical diffusion of the bipyridinium building blocks conspire in defining the charge transport properties of these fascinating electroactive assemblies. Often, the matrix of electron-deficient bipyridinium dications can be exploited to entrap electron-rich analytes. Electrostatic interactions promote the supramolecular association of the guests with the surface-confined host matrix. Furthermore, chromophoric sites can be coupled to the bipyridinium dications to produce photosensitive arrays capable of harvesting light and generating current. Thus, thorough investigations on the fundamental properties of these functional molecule-based materials can lead to promising applications in electroanalysis and solar energy conversion, while contributing to advances in the basic understanding of electron transport in interfacial assemblies.

  17. Attosecond Electron Wave-Packet Interference Observed by Transient Absorption

    SciTech Connect

    Holler, M.; Schapper, F.; Gallmann, L.; Keller, U.

    2011-03-25

    We perform attosecond time-resolved transient absorption spectroscopy around the first ionization threshold of helium and observe rapid oscillations of the absorption of the individual harmonics as a function of time delay with respect to a superimposed, moderately strong infrared laser field. The phase relation between the absorption modulation of individual harmonics gives direct evidence for the interference of transiently bound electronic wave packets as the mechanism behind the absorption modulation.

  18. Attosecond electron wave-packet interference observed by transient absorption.

    PubMed

    Holler, M; Schapper, F; Gallmann, L; Keller, U

    2011-03-25

    We perform attosecond time-resolved transient absorption spectroscopy around the first ionization threshold of helium and observe rapid oscillations of the absorption of the individual harmonics as a function of time delay with respect to a superimposed, moderately strong infrared laser field. The phase relation between the absorption modulation of individual harmonics gives direct evidence for the interference of transiently bound electronic wave packets as the mechanism behind the absorption modulation.

  19. Electronic Transport in Carbon Nanomaterials

    SciTech Connect

    Lopez-Benzanilla, Alejandro; Meunier, Vincent; Sumpter, Bobby G; Roche, Stephan; Cruz Silva, Eduardo

    2012-01-01

    Over the past decade, transport measurements on individual single-wall nanotubes have played a prominent role in developing our understanding of this novel carbon conductor. These measurements have identified both metallic and semiconducting nanotubes, determined their dominant electronic scattering mechanisms, and elucidated in great detail the properties of their quantized energy spectrum. Recent technological breakthroughs in nanotube device fabrication and electronic measurement have made possible experiments of unprecedented precision that reveal new and surprising phenomena. In this review, we present the fundamental properties of nanotubes side by side with the newest discoveries and also discuss some of the most exciting emerging directions.

  20. Mesoscopic electronics beyond DC transport

    NASA Astrophysics Data System (ADS)

    di Carlo, Leonardo

    Since the inception of mesoscopic electronics in the 1980's, direct current (dc) measurements have underpinned experiments in quantum transport. Novel techniques complementing dc transport are becoming paramount to new developments in mesoscopic electronics, particularly as the road is paved toward quantum information processing. This thesis describes seven experiments on GaAs/AlGaAs and graphene nanostructures unified by experimental techniques going beyond traditional dc transport. Firstly, dc current induced by microwave radiation applied to an open chaotic quantum dot is investigated. Asymmetry of mesoscopic fluctuations of induced current in perpendicular magnetic field is established as a tool for separating the quantum photovoltaic effect from classical rectification. A differential charge sensing technique is next developed using integrated quantum point contacts to resolve the spatial distribution of charge inside a double quantum clot. An accurate method for determining interdot tunnel coupling and electron temperature using charge sensing is demonstrated. A two-channel system for detecting current noise in mesoscopic conductors is developed, enabling four experiments where shot noise probes transmission properties not available in dc transport and Johnson noise serves as an electron thermometer. Suppressed shot noise is observed in quantum point contacts at zero parallel magnetic field, associated with the 0.7 structure in conductance. This suppression evolves with increasing field into the shot-noise signature of spin-lifted mode degeneracy. Quantitative agreement is found with a phenomenological model for density-dependent mode splitting. Shot noise measurements of multi-lead quantum-dot structures in the Coulomb blockade regime distill the mechanisms by which Coulomb interaction and quantum indistinguishability correlate electron flow. Gate-controlled sign reversal of noise cross correlation in two capacitively-coupled dots is observed, and shown to

  1. Electron Transport in Hall Thrusters

    NASA Astrophysics Data System (ADS)

    McDonald, Michael Sean

    Despite high technological maturity and a long flight heritage, computer models of Hall thrusters remain dependent on empirical inputs and a large part of thruster development to date has been heavily experimental in nature. This empirical approach will become increasingly unsustainable as new high-power thrusters tax existing ground test facilities and more exotic thruster designs stretch and strain the boundaries of existing design experience. The fundamental obstacle preventing predictive modeling of Hall thruster plasma properties and channel erosion is the lack of a first-principles description of electron transport across the strong magnetic fields between the cathode and anode. In spite of an abundance of proposed transport mechanisms, accurate assessments of the magnitude of electron current due to any one mechanism are scarce, and comparative studies of their relative influence on a single thruster platform simply do not exist. Lacking a clear idea of what mechanism(s) are primarily responsible for transport, it is understandably difficult for the electric propulsion scientist to focus his or her theoretical and computational tools on the right targets. This work presents a primarily experimental investigation of collisional and turbulent Hall thruster electron transport mechanisms. High-speed imaging of the thruster discharge channel at tens of thousands of frames per second reveals omnipresent rotating regions of elevated light emission, identified with a rotating spoke instability. This turbulent instability has been shown through construction of an azimuthally segmented anode to drive significant cross-field electron current in the discharge channel, and suggestive evidence points to its spatial extent into the thruster near-field plume as well. Electron trajectory simulations in experimentally measured thruster electromagnetic fields indicate that binary collisional transport mechanisms are not significant in the thruster plume, and experiments

  2. Electron transport in granular metals.

    PubMed

    Altland, Alexander; Glazman, Leonid I; Kamenev, Alex

    2004-01-16

    We consider thermodynamic and transport properties of a long granular array with strongly connected grains (intergrain conductance g>1). We find that the system's conductance and differential capacitance exhibits activated behavior, approximately exp([-T(*)/T]. The gap T(*) represents the energy needed to create a long single-electron charge soliton propagating through the array. This scale is parametrically larger than the energy at which conventional perturbation theory breaks down.

  3. Electronic transport in unconventional superconductors

    SciTech Connect

    Graf, M.J.

    1998-12-31

    The author investigates the electron transport coefficients in unconventional superconductors at low temperatures, where charge and heat transport are dominated by electron scattering from random lattice defects. He discusses the features of the pairing symmetry, Fermi surface, and excitation spectrum which are reflected in the low temperature heat transport. For temperatures {kappa}{sub B}T {approx_lt} {gamma} {much_lt} {Delta}{sub 0}, where {gamma} is the bandwidth of impurity induced Andreev states, certain eigenvalues become universal, i.e., independent of the impurity concentration and phase shift. Deep in the superconducting phase ({kappa}{sub B}T {approx_lt} {gamma}) the Wiedemann-Franz law, with Sommerfeld`s value of the Lorenz number, is recovered. He compares the results for theoretical models of unconventional superconductivity in high-{Tc} and heavy fermion superconductors with experiment. The findings show that impurities are a sensitive probe of the low-energy excitation spectrum, and that the zero-temperature limit of the transport coefficients provides an important test of the order parameter symmetry.

  4. Regulation of Intestinal Glucose Absorption by Ion Channels and Transporters.

    PubMed

    Chen, Lihong; Tuo, Biguang; Dong, Hui

    2016-01-14

    The absorption of glucose is electrogenic in the small intestinal epithelium. The major route for the transport of dietary glucose from intestinal lumen into enterocytes is the Na⁺/glucose cotransporter (SGLT1), although glucose transporter type 2 (GLUT2) may also play a role. The membrane potential of small intestinal epithelial cells (IEC) is important to regulate the activity of SGLT1. The maintenance of membrane potential mainly depends on the activities of cation channels and transporters. While the importance of SGLT1 in glucose absorption has been systemically studied in detail, little is currently known about the regulation of SGLT1 activity by cation channels and transporters. A growing line of evidence suggests that cytosolic calcium ([Ca(2+)]cyt) can regulate the absorption of glucose by adjusting GLUT2 and SGLT1. Moreover, the absorption of glucose and homeostasis of Ca(2+) in IEC are regulated by cation channels and transporters, such as Ca(2+) channels, K⁺ channels, Na⁺/Ca(2+) exchangers, and Na⁺/H⁺ exchangers. In this review, we consider the involvement of these cation channels and transporters in the regulation of glucose uptake in the small intestine. Modulation of them may be a potential strategy for the management of obesity and diabetes.

  5. Absorption and Transport of Sea Cucumber Saponins from Apostichopus japonicus.

    PubMed

    Li, Shuai; Wang, Yuanhong; Jiang, Tingfu; Wang, Han; Yang, Shuang; Lv, Zhihua

    2016-01-01

    The present study is focused on the intestinal absorption of sea cucumber saponins. We determined the pharmacokinetic characteristics and bioavailability of Echinoside A and Holotoxin A₁; the findings indicated that the bioavailability of Holotoxin A₁ was lower than Echinoside A. We inferred that the differences in chemical structure between compounds was a factor that explained their different characteristics of transport across the intestine. In order to confirm the absorption characteristics of Echinoside A and Holotoxin A₁, we examined their transport across Caco-2 cell monolayer and effective permeability by single-pass intestinal perfusion. The results of Caco-2 cell model indicate that Echinoside A is transported by passive diffusion, and not influenced by the exocytosis of P-glycoprotein (P-gp, expressed in the apical side of Caco-2 monolayers as the classic inhibitor). The intestinal perfusion also demonstrated well the absorption of Echinoside A and poor absorption of Holotoxin A₁, which matched up with the result of the Caco-2 cell model. The results demonstrated our conjecture and provides fundamental information on the relationship between the chemical structure of these sea cucumber saponins and their absorption characteristics, and we believe that our findings build a foundation for the further metabolism study of sea cucumber saponins and contribute to the further clinical research of saponins. PMID:27322290

  6. Absorption and Transport of Sea Cucumber Saponins from Apostichopus japonicus.

    PubMed

    Li, Shuai; Wang, Yuanhong; Jiang, Tingfu; Wang, Han; Yang, Shuang; Lv, Zhihua

    2016-01-01

    The present study is focused on the intestinal absorption of sea cucumber saponins. We determined the pharmacokinetic characteristics and bioavailability of Echinoside A and Holotoxin A₁; the findings indicated that the bioavailability of Holotoxin A₁ was lower than Echinoside A. We inferred that the differences in chemical structure between compounds was a factor that explained their different characteristics of transport across the intestine. In order to confirm the absorption characteristics of Echinoside A and Holotoxin A₁, we examined their transport across Caco-2 cell monolayer and effective permeability by single-pass intestinal perfusion. The results of Caco-2 cell model indicate that Echinoside A is transported by passive diffusion, and not influenced by the exocytosis of P-glycoprotein (P-gp, expressed in the apical side of Caco-2 monolayers as the classic inhibitor). The intestinal perfusion also demonstrated well the absorption of Echinoside A and poor absorption of Holotoxin A₁, which matched up with the result of the Caco-2 cell model. The results demonstrated our conjecture and provides fundamental information on the relationship between the chemical structure of these sea cucumber saponins and their absorption characteristics, and we believe that our findings build a foundation for the further metabolism study of sea cucumber saponins and contribute to the further clinical research of saponins.

  7. Absorption and Transport of Sea Cucumber Saponins from Apostichopus japonicus

    PubMed Central

    Li, Shuai; Wang, Yuanhong; Jiang, Tingfu; Wang, Han; Yang, Shuang; Lv, Zhihua

    2016-01-01

    The present study is focused on the intestinal absorption of sea cucumber saponins. We determined the pharmacokinetic characteristics and bioavailability of Echinoside A and Holotoxin A1; the findings indicated that the bioavailability of Holotoxin A1 was lower than Echinoside A. We inferred that the differences in chemical structure between compounds was a factor that explained their different characteristics of transport across the intestine. In order to confirm the absorption characteristics of Echinoside A and Holotoxin A1, we examined their transport across Caco-2 cell monolayer and effective permeability by single-pass intestinal perfusion. The results of Caco-2 cell model indicate that Echinoside A is transported by passive diffusion, and not influenced by the exocytosis of P-glycoprotein (P-gp, expressed in the apical side of Caco-2 monolayers as the classic inhibitor). The intestinal perfusion also demonstrated well the absorption of Echinoside A and poor absorption of Holotoxin A1, which matched up with the result of the Caco-2 cell model. The results demonstrated our conjecture and provides fundamental information on the relationship between the chemical structure of these sea cucumber saponins and their absorption characteristics, and we believe that our findings build a foundation for the further metabolism study of sea cucumber saponins and contribute to the further clinical research of saponins. PMID:27322290

  8. Molecular shock response of explosives: electronic absorption spectroscopy

    SciTech Connect

    Mcgrne, Shawn D; Moore, David S; Whitley, Von H; Bolme, Cindy A; Eakins, Daniel E

    2009-01-01

    Electronic absorption spectroscopy in the range 400-800 nm was coupled to ultrafast laser generated shocks to begin addressing the question of the extent to which electronic excitations are involved in shock induced reactions. Data are presented on shocked polymethylmethacrylate (PMMA) thin films and single crystal pentaerythritol tetranitrate (PETN). Shocked PMMA exhibited thin film interference effects from the shock front. Shocked PETN exhibited interference from the shock front as well as broadband increased absorption. Relation to shock initiation hypotheses and the need for time dependent absorption data (future experiments) is briefly discussed.

  9. Hysteresis and saturation of intersubband absorption by electrons on helium

    NASA Astrophysics Data System (ADS)

    Ryvkine, Dmitri; Lea, Michael; Dykman, Mark

    2006-03-01

    We propose a mechanism, develop a theory, and provide experimental data that demonstrate hysteresis of resonant inter-subband absorption by a quasi two-dimensional electron system on the surface of helium. The electrons form a strongly correlated nondegenerate electron liquid. The absorption occurs at the frequency of the transition from the ground to the first excited state of motion normal to the helium surface. The lifetime of the excited state is extremely long, 0.1 μs at 0.3 K, leading to strong absorption nonlinearity even for low radiation intensity [1]. Besides absorption saturation, radiation-induced occupation of the excited subband causes a shift of the resonant transition frequency. We show that this shift leads to absorption hysteresis with varying radiation frequency or intensity. As a result of electron correlations, the in-plane motion in all subbands is described by the same electron temperature, which is found self-consistently. The results bear on quantum computing with electrons on helium, since they demonstrate resonant transitions responsible for a single-qubit operation; the hysteresis results from the same mechanism that leads to two-qubit operations. 1. E. Collin et al., Phys. Rev. Lett. 89, 245301 (2002)

  10. "Stirred, Not Shaken": Vibrational Coherence Can Speed Up Electronic Absorption.

    PubMed

    Chang, Bo Y; Shin, Seokmin; Sola, Ignacio R

    2015-08-27

    We have recently proposed a laser control scheme for ultrafast absorption in multilevel systems by parallel transfer (J. Phys. Chem. Lett. 2015, 6, 1724). In this work we develop an analytical model that better takes into account the main features of electronic absorption in molecules. We show that the initial vibrational coherence in the ground electronic state can be used to greatly enhance the rate and yield of absorption when ultrashort pulses are used, provided that the phases of the coherences are taken into account. On the contrary, the initial coherence plays no role in the opposite limit, when a single long pulse drives the optical transition. The theory is tested by numerical simulations in the first absorption band of Na2.

  11. Electronic structure and optic absorption of phosphorene under strain

    NASA Astrophysics Data System (ADS)

    Duan, Houjian; Yang, Mou; Wang, Ruiqiang

    2016-07-01

    We studied the electronic structure and optic absorption of phosphorene (monolayer of black phosphorus) under strain. Strain was found to be a powerful tool for the band structure engineering. The in-plane strain in armchair or zigzag direction changes the effective mass components along both directions, while the vertical strain only has significant effect on the effective mass in the armchair direction. The band gap is narrowed by compressive in-plane strain and tensile vertical strain. Under certain strain configurations, the gap is closed and the energy band evolves to the semi-Dirac type: the dispersion is linear in the armchair direction and is gapless quadratic in the zigzag direction. The band-edge optic absorption is completely polarized along the armchair direction, and the polarization rate is reduced when the photon energy increases. Strain not only changes the absorption edge (the smallest photon energy for electron transition), but also the absorption polarization.

  12. Absorption and Transport of Fluorescent Brighteners by Microorganisms

    PubMed Central

    Darken, Marjorie A.

    1962-01-01

    The absorption of brighteners by living cells and their transport to subsequent growth is described. Brighteners are highly fluorescent, ultraviolet-absorbing compounds which appear to be essentially nontoxic, stable biological markers. They have been effectively absorbed by growing cultures of bacteria, yeasts, actinomycetes, and higher fungi, with active growth centers evidencing the greatest flourescence. Images FIG. 2 FIG. 3 FIG. 4 FIG. 5 FIG. 6 FIG. 7 FIG. 8 FIG. 9 FIG. 10-11 PMID:14025111

  13. Root absorption and transport behavior of technetium in soybean

    SciTech Connect

    Cataldo, D.A.; Wildung, R.E.; Garland, T.R.

    1983-01-01

    The absorption characteristics and mechanisms of pertechnetate (TcO/sub 4//sup -/) uptake by hydroponically grown soybean seedlings (Glycine max cv Williams) were determined. Absorption from 10 micromolar solutions was linear for at least 6 hours, with 30% of the absorbed TcO/sub 4//sup -/ being transferred to the shoot. Evaluation of concentration-dependent adsorption rates from solutions containing 0.02 to 10 micromolar TcO/sub 4//sup -/ shows the presence of multiphasic absorption isotherms with calculated K/sub s/ values of 0.09, 8.9, and 54 micromolar for intact seedlings. The uptake of TcO/sub 4//sup -/ was inhibited by a 4-fold concentration excess of sulfate, phosphate, selenate, molybdate, and permanganate; no reduction was noted with borate, nitrate, tungstate, perrhenate, iodate, or vanadate. Analyses of kinetics of interaction TcO/sub 4//sup -/ and inhibiting anions show permanganate to be a noncompetitive inhibitor, while sulfate, phosphate, and selenate, and molybdate exhibit characteristics of competitive inhibitors of TcO/sub 4//sup -/ transport suggesting involvement of a common transport process.

  14. Coupled electron-photon radiation transport

    SciTech Connect

    Lorence, L.; Kensek, R.P.; Valdez, G.D.; Drumm, C.R.; Fan, W.C.; Powell, J.L.

    2000-01-17

    Massively-parallel computers allow detailed 3D radiation transport simulations to be performed to analyze the response of complex systems to radiation. This has been recently been demonstrated with the coupled electron-photon Monte Carlo code, ITS. To enable such calculations, the combinatorial geometry capability of ITS was improved. For greater geometrical flexibility, a version of ITS is under development that can track particles in CAD geometries. Deterministic radiation transport codes that utilize an unstructured spatial mesh are also being devised. For electron transport, the authors are investigating second-order forms of the transport equations which, when discretized, yield symmetric positive definite matrices. A novel parallelization strategy, simultaneously solving for spatial and angular unknowns, has been applied to the even- and odd-parity forms of the transport equation on a 2D unstructured spatial mesh. Another second-order form, the self-adjoint angular flux transport equation, also shows promise for electron transport.

  15. Absorption and transport of milk calcium by infant rats

    SciTech Connect

    Blake, H.H.; Henning, S.J. )

    1988-01-01

    All previous studies of Ca absorption in the developing animal have used simple salts of Ca. The aims of the current study are (1) to determine the predominant form of Ca in rat milk and (2) to compare the absorption of milk Ca and CaCl{sub 2}. In vivo-labeled rat milk was obtained by injecting lactating dams with {sup 45}CaCl{sub 2}. Distribution of {sup 45}Ca in the cream, whey, and casein fractions was determined by differential centrifugation, the values being 0.3, 5, and 95%, respectively. To study Ca absorption, rats aged 14 and 28 days received either {sup 45}Ca-milk or {sup 45}CaCl{sub 2} by intragastric intubation. At 14 days, transport of milk Ca into the carcass was significantly slower than that of CaCl{sub 2}, although by 6 h postintubation both had plateaued at {approximately}92% of dose. At 28 days, the time course of transport was the same for the two forms of Ca, and the plateau was not significantly different from that at 14 days. In the younger animals, more Ca from milk than from CaCl{sub 2} was retained in gastrointestinal tissue. Quantitation of {sup 45}Ca in various segments of the gastrointestinal tract showed that the greater retention of milk Ca occurred in the stomach, the duodenum, and the distal jejunum. The authors conclude that milk Ca is efficiently absorbed by the suckling rat, possibly in a protein-bound form. The mechanism of the absorptive process awaits further investigation.

  16. Charge Transport and Light Absorption in Conjugated Systems from Extended HÜCKEL Method and Marcus Theory

    NASA Astrophysics Data System (ADS)

    To, Tran Thinh; Adams, Stefan

    2012-06-01

    A simple first principle model was developed based on extended Hückel-type orbital calculation, Marcus electron transport theory and two-dimensional-electron-gas model for the treatment of charge transport in conjugated polymers. Though simple and easy to compute, the effect of the applied electric-field is factored in. Based on this, a complete one-dimensional device model with a single layer of conjugated polymer sandwiched between two electrodes was developed with poly(3-hexylthiophene) (P3HT) as a case study. Simulated J-V curves show that π-π charge transport is much more pronounced than intra-chain transport, hence agree with previous findings. Using the same framework, we also calculated the absorption spectra of P3HT by considering the electronic energy barrier for electronic transitions that would satisfy Franck-Condon principle. Absorption spectra closely harmonize to experimental UV-Vis result. The model also reveals intra-chain electronic transitions to be the dominant absorption mechanism. All parameters of the model are obtained from either ab-initio Density Functional Theory (DFT) or Molecular Dynamics (MD) calculations, so that this model is capable of predicting charge transport and light absorption properties of new conjugated polymers without introducing fit parameters.

  17. Electron Wavepacket Interference Observed by Attosecond Transient Absorption Spectroscopy

    NASA Astrophysics Data System (ADS)

    Gallmann, L.; Holler, M.; Schapper, F.; Keller, U.

    Attosecond time-resolved transient absorption spectroscopy is performed in a dense helium target by superimposing an attosecond pulse train (APT) with a moderately strong infrared field. We observe rapid oscillations of the absorption of the individual harmonics as a function of time-delay between the APT and IR field even for harmonic energies well below the ionization threshold. The phase dependence of these modulations on atto-chirp and IR intensity yields direct evidence for the interference of transiently bound electronic wavepackets as the underlying mechanism.

  18. Measurements of parallel electron velocity distributions using whistler wave absorption.

    PubMed

    Thuecks, D J; Skiff, F; Kletzing, C A

    2012-08-01

    We describe a diagnostic to measure the parallel electron velocity distribution in a magnetized plasma that is overdense (ω(pe) > ω(ce)). This technique utilizes resonant absorption of whistler waves by electrons with velocities parallel to a background magnetic field. The whistler waves were launched and received by a pair of dipole antennas immersed in a cylindrical discharge plasma at two positions along an axial background magnetic field. The whistler wave frequency was swept from somewhat below and up to the electron cyclotron frequency ω(ce). As the frequency was swept, the wave was resonantly absorbed by the part of the electron phase space density which was Doppler shifted into resonance according to the relation ω - k([parallel])v([parallel]) = ω(ce). The measured absorption is directly related to the reduced parallel electron distribution function integrated along the wave trajectory. The background theory and initial results from this diagnostic are presented here. Though this diagnostic is best suited to detect tail populations of the parallel electron distribution function, these first results show that this diagnostic is also rather successful in measuring the bulk plasma density and temperature both during the plasma discharge and into the afterglow.

  19. Measurements of parallel electron velocity distributions using whistler wave absorption

    SciTech Connect

    Thuecks, D. J.; Skiff, F.; Kletzing, C. A.

    2012-08-15

    We describe a diagnostic to measure the parallel electron velocity distribution in a magnetized plasma that is overdense ({omega}{sub pe} > {omega}{sub ce}). This technique utilizes resonant absorption of whistler waves by electrons with velocities parallel to a background magnetic field. The whistler waves were launched and received by a pair of dipole antennas immersed in a cylindrical discharge plasma at two positions along an axial background magnetic field. The whistler wave frequency was swept from somewhat below and up to the electron cyclotron frequency {omega}{sub ce}. As the frequency was swept, the wave was resonantly absorbed by the part of the electron phase space density which was Doppler shifted into resonance according to the relation {omega}-k{sub ||v||} = {omega}{sub ce}. The measured absorption is directly related to the reduced parallel electron distribution function integrated along the wave trajectory. The background theory and initial results from this diagnostic are presented here. Though this diagnostic is best suited to detect tail populations of the parallel electron distribution function, these first results show that this diagnostic is also rather successful in measuring the bulk plasma density and temperature both during the plasma discharge and into the afterglow.

  20. PREDICTING DRUG DISPOSITION, ABSORPTION / ELIMINATION / TRANSPORTER INTERPLAY AND THE ROLE OF FOOD ON DRUG ABSORPTION

    PubMed Central

    Custodio, Joseph M.; Wu, Chi-Yuan; Benet, Leslie Z.

    2008-01-01

    The ability to predict drug disposition involves concurrent consideration of many chemical and physiological variables and the effect of food on the rate and extent of availability adds further complexity due to postprandial changes in the gastrointestinal (GI) tract. A system that allows for the assessment of the multivariate interplay occurring following administration of an oral dose, in the presence or absence of meal, would greatly benefit the early stages of drug development. This is particularly true in an era when the majority of new molecular entities are highly permeable, poorly soluble, extensively metabolized compounds (BDDCS Class 2), which present the most complicated relationship in defining the impact of transporters due to the marked effects of transporter-enzyme interplay. This review evaluates the GI luminal environment by taking into account the absorption / transport / elimination interplay and evaluates the physiochemical property issues by taking into account the importance of solubility, permeability and metabolism. We concentrate on the BDDCS and its utility in predicting drug disposition. Furthermore, we focus on the effect of food on the extent of drug availability (F), which appears to follow closely what might be expected if a significant effect of high fat meals is inhibition of transporters. That is, high fat meals and lipidic excipients would be expected to have little effect on F for Class 1 drugs; they would increase F of Class 2 drugs, while decreasing F for Class 3 drugs. PMID:18199522

  1. Electron paramagnetic resonance and optical absorption spectral studies on chalcocite

    NASA Astrophysics Data System (ADS)

    Reddy, S. Lakshmi; Fayazuddin, Md.; Frost, Ray L.; Endo, Tamio

    2007-11-01

    A chalcocite mineral sample of Shaha, Congo is used in the present study. An electron paramagnetic resonance (EPR) study on powdered sample confirms the presence of Mn(II), Fe(III) and Cu(II). Optical absorption spectrum indicates that Fe(III) impurity is present in octahedral structure whereas Cu(II) is present in rhombically distorted octahedral environment. Mid-infrared results are due to water and sulphate fundamentals.

  2. Electron paramagnetic resonance and optical absorption spectral studies on chalcocite.

    PubMed

    Reddy, S Lakshmi; Fayazuddin, Md; Frost, Ray L; Endo, Tamio

    2007-11-01

    A chalcocite mineral sample of Shaha, Congo is used in the present study. An electron paramagnetic resonance (EPR) study on powdered sample confirms the presence of Mn(II), Fe(III) and Cu(II). Optical absorption spectrum indicates that Fe(III) impurity is present in octahedral structure whereas Cu(II) is present in rhombically distorted octahedral environment. Mid-infrared results are due to water and sulphate fundamentals. PMID:17324611

  3. NASA three-laser airborne differential absorption lidar system electronics

    NASA Technical Reports Server (NTRS)

    Allen, R. J.; Copeland, G. D.

    1984-01-01

    The system control and signal conditioning electronics of the NASA three laser airborne differential absorption lidar (DIAL) system are described. The multipurpose DIAL system was developed for the remote measurement of gas and aerosol profiles in the troposphere and lower stratosphere. A brief description and photographs of the majority of electronics units developed under this contract are presented. The precision control system; which includes a master control unit, three combined NASA laser control interface/quantel control units, and three noise pulse discriminator/pockels cell pulser units; is described in detail. The need and design considerations for precision timing and control are discussed. Calibration procedures are included.

  4. Transport experiments with Dirac electrons

    NASA Astrophysics Data System (ADS)

    Checkelsky, Joseph George

    This thesis presents transport experiments performed on solid state systems in which the behavior of the charge carriers can be described by the Dirac equation. Unlike the massive carriers in a typical material, in these systems the carriers behave like massless fermions with a photon-like dispersion predicted to greatly modify their spin and charge transport properties. The first system studied is graphene, a crystalline monolayer of carbon arranged in a hexagonal lattice. The band structure calculated from the hexagonal lattice has the form of the massless Dirac Hamiltonian. At the charge neutral Dirac point, we find that application of a magnetic field drives a transition to an insulating state. We also study the thermoelectric properties of graphene and find that the states near the Dirac point have a unique response compared to those at higher charge density. The second system is the 3D topological insulator Bi2Se3, where a Dirac-like dispersion for states on the 2D surface of the insulating 3D crystal arises as a result of the topology of the 3D bands and time reversal symmetry. To access the transport properties of the 2D states, we suppress the remnant bulk conduction channel by chemical doping and electrostatic gating. In bulk crystals we find strong quantum corrections to transport at low temperature when the bulk conduction channel is maximally suppressed. In microscopic crystals we are able better to isolate the surface conduction channel properties. We identify in-gap conducting states that have relatively high mobility compared to the bulk and exhibit weak anti-localization, consistent with predictions for protected 2D surface states with strong spin-orbit coupling.

  5. The Electron Transport Chain: An Interactive Simulation

    ERIC Educational Resources Information Center

    Romero, Chris; Choun, James

    2014-01-01

    This activity provides students an interactive demonstration of the electron transport chain and chemiosmosis during aerobic respiration. Students use simple, everyday objects as hydrogen ions and electrons and play the roles of the various proteins embedded in the inner mitochondrial membrane to show how this specific process in cellular…

  6. Monte Carlo electron/photon transport

    SciTech Connect

    Mack, J.M.; Morel, J.E.; Hughes, H.G.

    1985-01-01

    A review of nonplasma coupled electron/photon transport using Monte Carlo method is presented. Remarks are mainly restricted to linerarized formalisms at electron energies from 1 keV to 1000 MeV. Applications involving pulse-height estimation, transport in external magnetic fields, and optical Cerenkov production are discussed to underscore the importance of this branch of computational physics. Advances in electron multigroup cross-section generation is reported, and its impact on future code development assessed. Progress toward the transformation of MCNP into a generalized neutral/charged-particle Monte Carlo code is described. 48 refs.

  7. Electron transport through single carbon nanotubes

    SciTech Connect

    Schenkel, Thomas; Chai, G.; Heinrich, H.; Chow, L.; Schenkel, T.

    2007-08-01

    We report on the transport of energetic electrons through single, well aligned multi-wall carbon nanotubes (CNT). Embedding of CNTs in a protective carbon fiber coating enables the application of focused ion beam based sample preparation techniques for the non-destructive isolation and alignment of individual tubes. Aligned tubes with lengths of 0.7 to 3 mu m allow transport of 300 keV electrons in a transmission electron microscope through their hollow cores at zero degree incident angles and for a misalignment of up to 1 degree.

  8. Absorption and transport of cholesterol autoxidation derivatives in rabbits

    SciTech Connect

    Peng, S.K.; Morin, R.J.; Phillips, G.A.; Xia, G.Z.

    1986-03-01

    Spontaneously autoxidized products of cholesterol have been demonstrated to be angiotoxic and possibly atherogenic. This study investigates the absorption and transport of these cholesterol oxidation derivatives (COD's) as compared to cholesterol. /sup 14/C-labeled cholesterol autoxidized by incubation in a 60/sup 0/C water bath for 5 weeks, then suspended in gelatin and given to New Zealand white rabbits by gastric gavage. Rabbits were sacrificed 24 hours after treatment. COD's were separated by thin layer chromatography (TLC) and radioactivities of each COD and cholesterol were measured. Percentages of each COD and cholesterol in the original mixture before administration and in the rabbits' serum after administration are almost identical, suggesting that the rates of absorption of COD's are not significantly different from that of cholesterol. Lipoproteins were fractionated by ultracentrifugation into VLDL, LDL and HDL. Radioactivities of each COD separated by TLC in each lipoprotein fraction showed that cholestane-3..beta..,5..cap alpha..,6..beta..-triol, 7..cap alpha..- and 7..beta..-hydroxycholesterol and 7-ketocholesterol were predominantly present in VLDL (3 x serum concentration) and 25-hydroxycholesterol was predominantly in LDL (2.5 x serum concentration). HDL contained only minute amounts of COD's. The increased levels of COD's in VLDL and LDL may contribute to the atherogenicity of these lipoprotein.

  9. EPR and electronic absorption spectra of copper bearing turquoise mineral

    NASA Astrophysics Data System (ADS)

    Sharma, K. B. N.; Moorthy, L. R.; Reddy, B. J.; Vedanand, S.

    1988-10-01

    Electron paramagnetic resonance and optical absorption spectra of turquoise have been studied both at room and low temperatures. It is concluded from the EPR spectra that the ground state of Cu 2+ ion in turquoise is 2A g(d x2- y2) and it is sited in an elongated rhombic octahedron (D 2π). The observed absorption bands at 14970 and 18354 cm -1 are assigned at 2A g→ 2B 1 g( dx2- y2→ xy) and 2A g→[ su2B 3g(d x 2-y 2→d yz) respectively assuming D 2π symmetry which are inconsistent with EPR studies. The three bands in the NIR region are attributed to combinations of fundamental modes of the H 2O molecule present in the sample.

  10. Electronic Transport in Organic Molecules

    NASA Astrophysics Data System (ADS)

    Tian, W.; Samanta, M. P.; Henderson, J. I.; Kubiak, C. P.; Datta, S.

    1996-03-01

    A systematic theoretical study of the conductance of a class of organic molecules connected between two gold cantact pads will be presented. This class of molecules consists of oligomers of benzene rings linked at their para-positions and terminated with suitable ligand end groups designed to bond to gold substrates. Such molecules are currently being investigated experimentally for use as interconnectors in nanoscale electronic devices (J.Guay et al, J.Am.Chem.Soc., 115,1869, (1993); M.Dorogi et al, Phys. Rev. B52,9071,(1995); D.B.Janes et al, Superlatt. and Microstruc., in press). Analytical and numerical results will be presented illustrating effects of Metal Induced Gap States (MIGS), end group atoms, geometric and molecular structure on the measured conductance.

  11. Photosynthetic electron transport system promotes synthesis of Au-nanoparticles.

    PubMed

    Shabnam, Nisha; Pardha-Saradhi, P

    2013-01-01

    In this communication, a novel, green, efficient and economically viable light mediated protocol for generation of Au-nanoparticles using most vital organelle, chloroplasts, of the plant system is portrayed. Thylakoids/chloroplasts isolated from Potamogeton nodosus (an aquatic plant) and Spinacia oleracea (a terrestrial plant) turned Au³⁺ solutions purple in presence of light of 600 µmol m⁻² s⁻¹ photon flux density (PFD) and the purple coloration intensified with time. UV-Vis spectra of these purple colored solutions showed absorption peak at ∼545 nm which is known to arise due to surface plasmon oscillations specific to Au-nanoparticles. However, thylakoids/chloroplasts did not alter color of Au³⁺ solutions in dark. These results clearly demonstrated that photosynthetic electron transport can reduce Au³⁺ to Au⁰ which nucleate to form Au-nanoparticles in presence of light. Transmission electron microscopic studies revealed that Au-nanoparticles generated by light driven photosynthetic electron transport system of thylakoids/chloroplasts were in range of 5-20 nm. Selected area electron diffraction and powder X-ray diffraction indicated crystalline nature of these nanoparticles. Energy dispersive X-ray confirmed that these nanoparticles were composed of Au. To confirm the potential of light driven photosynthetic electron transport in generation of Au-nanoparticles, thylakoids/chloroplasts were tested for their efficacy to generate Au-nanoparticles in presence of light of PFD ranging from 60 to 600 µmol m⁻² s⁻¹. The capacity of thylakoids/chloroplasts to generate Au-nanoparticles increased remarkably with increase in PFD, which further clearly demonstrated potential of light driven photosynthetic electron transport in reduction of Au³⁺ to Au⁰ to form nanoparticles. The light driven donation of electrons to metal ions by thylakoids/chloroplasts can be exploited for large scale production of nanoparticles. PMID:23976990

  12. Photosynthetic electron transport system promotes synthesis of Au-nanoparticles.

    PubMed

    Shabnam, Nisha; Pardha-Saradhi, P

    2013-01-01

    In this communication, a novel, green, efficient and economically viable light mediated protocol for generation of Au-nanoparticles using most vital organelle, chloroplasts, of the plant system is portrayed. Thylakoids/chloroplasts isolated from Potamogeton nodosus (an aquatic plant) and Spinacia oleracea (a terrestrial plant) turned Au³⁺ solutions purple in presence of light of 600 µmol m⁻² s⁻¹ photon flux density (PFD) and the purple coloration intensified with time. UV-Vis spectra of these purple colored solutions showed absorption peak at ∼545 nm which is known to arise due to surface plasmon oscillations specific to Au-nanoparticles. However, thylakoids/chloroplasts did not alter color of Au³⁺ solutions in dark. These results clearly demonstrated that photosynthetic electron transport can reduce Au³⁺ to Au⁰ which nucleate to form Au-nanoparticles in presence of light. Transmission electron microscopic studies revealed that Au-nanoparticles generated by light driven photosynthetic electron transport system of thylakoids/chloroplasts were in range of 5-20 nm. Selected area electron diffraction and powder X-ray diffraction indicated crystalline nature of these nanoparticles. Energy dispersive X-ray confirmed that these nanoparticles were composed of Au. To confirm the potential of light driven photosynthetic electron transport in generation of Au-nanoparticles, thylakoids/chloroplasts were tested for their efficacy to generate Au-nanoparticles in presence of light of PFD ranging from 60 to 600 µmol m⁻² s⁻¹. The capacity of thylakoids/chloroplasts to generate Au-nanoparticles increased remarkably with increase in PFD, which further clearly demonstrated potential of light driven photosynthetic electron transport in reduction of Au³⁺ to Au⁰ to form nanoparticles. The light driven donation of electrons to metal ions by thylakoids/chloroplasts can be exploited for large scale production of nanoparticles.

  13. Resistive Plate Chambers: electron transport and modeling

    NASA Astrophysics Data System (ADS)

    Bošnjaković, D.; Petrović, Z. Lj; Dujko, S.

    2014-12-01

    We study the electron transport in gas mixtures used by Resistive Plate Chambers (RPCs) in high energy physics experiments at CERN. Calculations are performed using a multi term theory for solving the Boltzmann equation. We identify the effects induced by non-conservative nature of electron attachment, including attachment heating of electrons and negative differential conductivity (NDC). NDC was observed only in the bulk component of drift velocity. Using our Monte Carlo technique, we calculate the spatially resolved transport properties in order to investigate the origin of these effects. We also present our microscopic approach to modeling of RPCs which is based on Monte Carlo method. Calculated results for a timing RPC show good agreement with an analytical model and experimental data. Different cross section sets for electron scattering in C2H2F4 are used for comparison and analysis.

  14. Numerical solution of the electron transport equation

    NASA Astrophysics Data System (ADS)

    Woods, Mark

    The electron transport equation has been solved many times for a variety of reasons. The main difficulty in its numerical solution is that it is a very stiff boundary value problem. The most common numerical methods for solving boundary value problems are symmetric collocation methods and shooting methods. Both of these types of methods can only be applied to the electron transport equation if the boundary conditions are altered with unrealistic assumptions because they require too many points to be practical. Further, they result in oscillating and negative solutions, which are physically meaningless for the problem at hand. For these reasons, all numerical methods for this problem to date are a bit unusual because they were designed to try and avoid the problem of extreme stiffness. This dissertation shows that there is no need to introduce spurious boundary conditions or invent other numerical methods for the electron transport equation. Rather, there already exists methods for very stiff boundary value problems within the numerical analysis literature. We demonstrate one such method in which the fast and slow modes of the boundary value problem are essentially decoupled. This allows for an upwind finite difference method to be applied to each mode as is appropriate. This greatly reduces the number of points needed in the mesh, and we demonstrate how this eliminates the need to define new boundary conditions. This method is verified by showing that under certain restrictive assumptions, the electron transport equation has an exact solution that can be written as an integral. We show that the solution from the upwind method agrees with the quadrature evaluation of the exact solution. This serves to verify that the upwind method is properly solving the electron transport equation. Further, it is demonstrated that the output of the upwind method can be used to compute auroral light emissions.

  15. Electron Transport Through Single Fullerene Molecules (abstract)

    NASA Astrophysics Data System (ADS)

    Stróżecka, Anna; Muthukumar, Kaliappan; Larsson, J. Andreas; Voigtländer, Bert

    2009-04-01

    Fullerenes show potential for applications in nanotechnology due to the possibility of tuning their properties by doping or functionalization. In particular, the endohedral doping of the hollow carbon cage with metal atoms allows changing the electronic and magnetic properties of the molecule without distorting the geometry of the outer shell. Here we present a low temperature scanning tunneling microscopy (STM) and spectroscopy study of the vibrational and transport properties of Ce2atC80 metallofullerenes. We observe that electron transport through the endohedral fullerene is strongly mediated by excitation of molecular vibrations, especially the dynamics of encapsulated atoms. We measure the conductance of the single-molecule junction upon contact between the molecule and the STM tip. To determine the role of doping atoms we compare the results obtained for the endohedrally doped species with those for a hollow fullerene. Analysis shows that localization of electron density on encapsulated atoms hinders the conduction process through the fullerene.

  16. Time-Resolved IR-Absorption Spectroscopy of Hot-Electron Dynamics in Satellite and Upper Conduction Bands in GaP

    NASA Technical Reports Server (NTRS)

    Cavicchia, M. A.; Alfano, R. R.

    1995-01-01

    The relaxation dynamics of hot electrons in the X6 and X7 satellite and upper conduction bands in GaP was directly measured by femtosecond UV-pump-IR-probe absorption spectroscopy. From a fit to the induced IR-absorption spectra the dominant scattering mechanism giving rise to the absorption at early delay times was determined to be intervalley scattering of electrons out of the X7 upper conduction-band valley. For long delay times the dominant scattering mechanism is electron-hole scattering. Electron transport dynamics of the upper conduction band of GaP has been time resolved.

  17. Regulation of Photosynthetic Electron Transport and Photoinhibition

    PubMed Central

    Roach, Thomas; Krieger-Liszkay, Anja Krieger

    2014-01-01

    Photosynthetic organisms and isolated photosystems are of interest for technical applications. In nature, photosynthetic electron transport has to work efficiently in contrasting environments such as shade and full sunlight at noon. Photosynthetic electron transport is regulated on many levels, starting with the energy transfer processes in antenna and ending with how reducing power is ultimately partitioned. This review starts by explaining how light energy can be dissipated or distributed by the various mechanisms of non-photochemical quenching, including thermal dissipation and state transitions, and how these processes influence photoinhibition of photosystem II (PSII). Furthermore, we will highlight the importance of the various alternative electron transport pathways, including the use of oxygen as the terminal electron acceptor and cyclic flow around photosystem I (PSI), the latter which seem particularly relevant to preventing photoinhibition of photosystem I. The control of excitation pressure in combination with the partitioning of reducing power influences the light-dependent formation of reactive oxygen species in PSII and in PSI, which may be a very important consideration to any artificial photosynthetic system or technical device using photosynthetic organisms. PMID:24678670

  18. The effect of electron-electron interaction induced dephasing on electronic transport in graphene nanoribbons

    SciTech Connect

    Kahnoj, Sina Soleimani; Touski, Shoeib Babaee; Pourfath, Mahdi E-mail: pourfath@iue.tuwien.ac.at

    2014-09-08

    The effect of dephasing induced by electron-electron interaction on electronic transport in graphene nanoribbons is theoretically investigated. In the presence of disorder in graphene nanoribbons, wavefunction of electrons can set up standing waves along the channel and the conductance exponentially decreases with the ribbon's length. Employing the non-equilibrium Green's function formalism along with an accurate model for describing the dephasing induced by electron-electron interaction, we show that this kind of interaction prevents localization and transport of electrons remains in the diffusive regime where the conductance is inversely proportional to the ribbon's length.

  19. Electron ripple injection concept for transport control

    SciTech Connect

    Choe, W.; Ono, M.; Hwang, Y.S.

    1992-01-01

    Recent experiments in many devices have provided firm evidence that the edge radial electric field profile differs between L- and H-modes, and that these fields can greatly modify transport in tokamak plasmas. A nonintrusive method for inducing radial electric field based on electron ripple injection is being developed by the CDX-U group. This technique utilizes a pair of special coils to create a local magnetic field ripple to trap the electrons at the edge of the plasma. The trapped electrons then drift into the plasma due to the [del]B drift. An ECH power is applied to accelerate electrons to sufficient perpendicular energy to penetrate into the plasma. Application of ECH power to the trapped electrons should provide the desired 20 A of electron current with electrons of a few keV of energy and v[perpendicular]/v[parallel] [much gt] 1. A controlled experiment to investigate the physics of ECH aided ripple injection has been designed on CDX-U. With the set of ripple coils designed for CDX-U, a ripple fraction of [delta] ([double bond] [del]B/B[sub av]) [approximately] 5% is attainable. At this ripple fraction, electrons are trapped if v[perpendicular]/v[parallel] [much gt] 1> (2[delta])[sup [minus][1/2

  20. Absorption characteristics of vapor transport equilibrated Er:LiNbO3 crystals

    NASA Astrophysics Data System (ADS)

    Zhang, De-Long; Pun, E. Y. B.; Chen, Xiao-Jun; Wang, Yan; Jin, Yue-Han; Zhu, Deng-Song; Wu, Zhong-Kang

    2002-04-01

    The visible and infrared transmission spectra of vapor transport equilibration (VTE) treated Er:LiNbO3 crystals, which have different doping levels (0.2%, 0.4%, and 2.0% Er per cation site), different cut orientation (X and Z cut) and different VTE duration (80, 120, 150, and 180 h), were recorded at room temperature in the wavelength range of 250-3700 nm. All of 2.0 mol % doped VTE crystals have precipitated whether X cut or Z cut, while the others have not. Their absorption characteristics were summarized and discussed in contrast to those of corresponding as-grown crystals. The OH- absorption feature of VTE treated Er:LiNbO3 is found to be different from that of pure VTE LiNbO3 crystal. The significant reduction of OH- absorption band implies that the hydrogen content in the VTE crystals has been reduced substantially whether the crystal precipitates or not. The electron transition absorption characteristics of the lower-doped, not precipitated crystals mainly include the higher transmittance, slight shift of peak or band position, slight absorption intensity change, the appearance of some additional peaks or bands, the narrowing of the peak width (full width at half maximum), and the definite blueshift of the optical absorption edge. The spectral changes are associated with the redistribution of Er3+ spectroscopic sites induced by the VTE procedure. In comparison with those lower-doped VTE crystals, the highly doped VTE crystals display more significant absorption characteristics: the significant enhancement of 1480 nm pumping band and the obvious weakening of 1531 nm peak, the appearance of many additional peaks in the infrared region, and the interesting evolution of the transmittance with the wavelength. These substantial spectral changes are unambiguously conducted with the formation of a precipitate ErNbO4 induced by the VTE treatment in these crystals. The mechanism for the formation of the precipitate has been tentatively explained from the viewpoint of

  1. Femtosecond X-ray absorption study of electron localization in photoexcited anatase TiO2

    PubMed Central

    Santomauro, F. G.; Lübcke, A.; Rittmann, J.; Baldini, E.; Ferrer, A.; Silatani, M.; Zimmermann, P.; Grübel, S.; Johnson, J. A.; Mariager, S. O.; Beaud, P.; Grolimund, D.; Borca, C.; Ingold, G.; Johnson, S.L.; Chergui, M.

    2015-01-01

    Transition metal oxides are among the most promising solar materials, whose properties rely on the generation, transport and trapping of charge carriers (electrons and holes). Identifying the latter’s dynamics at room temperature requires tools that combine elemental and structural sensitivity, with the atomic scale resolution of time (femtoseconds, fs). Here, we use fs Ti K-edge X-ray absorption spectroscopy (XAS) upon 3.49 eV (355 nm) excitation of aqueous colloidal anatase titanium dioxide nanoparticles to probe the trapping dynamics of photogenerated electrons. We find that their localization at Titanium atoms occurs in <300 fs, forming Ti3+ centres, in or near the unit cell where the electron is created. We conclude that electron localization is due to its trapping at pentacoordinated sites, mostly present in the surface shell region. The present demonstration of fs hard X-ray absorption capabilities opens the way to a detailed description of the charge carrier dynamics in transition metal oxides. PMID:26437873

  2. Femtosecond X-ray absorption study of electron localization in photoexcited anatase TiO2.

    PubMed

    Santomauro, F G; Lübcke, A; Rittmann, J; Baldini, E; Ferrer, A; Silatani, M; Zimmermann, P; Grübel, S; Johnson, J A; Mariager, S O; Beaud, P; Grolimund, D; Borca, C; Ingold, G; Johnson, S L; Chergui, M

    2015-10-06

    Transition metal oxides are among the most promising solar materials, whose properties rely on the generation, transport and trapping of charge carriers (electrons and holes). Identifying the latter's dynamics at room temperature requires tools that combine elemental and structural sensitivity, with the atomic scale resolution of time (femtoseconds, fs). Here, we use fs Ti K-edge X-ray absorption spectroscopy (XAS) upon 3.49 eV (355 nm) excitation of aqueous colloidal anatase titanium dioxide nanoparticles to probe the trapping dynamics of photogenerated electrons. We find that their localization at Titanium atoms occurs in <300 fs, forming Ti(3+) centres, in or near the unit cell where the electron is created. We conclude that electron localization is due to its trapping at pentacoordinated sites, mostly present in the surface shell region. The present demonstration of fs hard X-ray absorption capabilities opens the way to a detailed description of the charge carrier dynamics in transition metal oxides.

  3. Self-consistent electron transport in tokamaks

    SciTech Connect

    Gatto, R.; Chavdarovski, I.

    2007-09-15

    Electron particle, momentum, and energy fluxes in axisymmetric toroidal devices are derived from a version of the action-angle collision operator that includes both diffusion and drag in action-space [D. A. Hitchcock, R. D. Hazeltine, and S. M. Mahajan, Phys. Fluids 26, 2603 (1983); H. E. Mynick, J. Plasma Phys. 39, 303 (1988)]. A general result of the theory is that any contribution to transport originating directly from the toroidal frequency of the particle motion is constrained to be zero when the electron temperature is equal to the ion temperature. In particular, this constraint applies to those components of the particle and energy fluxes that are proportional to the magnetic shear, independent of the underlying turbulence and of whether the particles are trapped or untrapped. All the total fluxes describing collisionless transport of passing electrons in steady-state magnetic turbulence contain contributions proportional to the conventional thermodynamic drives, which are always outward, and contributions proportional to the magnetic shear, which have both magnitude and sign dependent on the ion-electron temperature ratio. The turbulent generalization of Ohm's law includes a hyper-resistive term, which flattens the current density profile on a fast time scale, and a turbulent electric field, which can have both signs depending on the electron-ion temperature ratio.

  4. Single-molecule junctions beyond electronic transport.

    PubMed

    Aradhya, Sriharsha V; Venkataraman, Latha

    2013-06-01

    The idea of using individual molecules as active electronic components provided the impetus to develop a variety of experimental platforms to probe their electronic transport properties. Among these, single-molecule junctions in a metal-molecule-metal motif have contributed significantly to our fundamental understanding of the principles required to realize molecular-scale electronic components from resistive wires to reversible switches. The success of these techniques and the growing interest of other disciplines in single-molecule-level characterization are prompting new approaches to investigate metal-molecule-metal junctions with multiple probes. Going beyond electronic transport characterization, these new studies are highlighting both the fundamental and applied aspects of mechanical, optical and thermoelectric properties at the atomic and molecular scales. Furthermore, experimental demonstrations of quantum interference and manipulation of electronic and nuclear spins in single-molecule circuits are heralding new device concepts with no classical analogues. In this Review, we present the emerging methods being used to interrogate multiple properties in single molecule-based devices, detail how these measurements have advanced our understanding of the structure-function relationships in molecular junctions, and discuss the potential for future research and applications.

  5. Computation of the ultraviolet absorption and electron inelastic scattering cross section of multishell fullerenes

    NASA Astrophysics Data System (ADS)

    Lucas, A. A.; Henrard, L.; Lambin, Ph.

    1994-01-01

    We develop a model in which the ultraviolet dielectric tensor of planar graphite is transported to the spherical geometry of a nanoscale multishell fullerene with a central cavity. This is accomplished by assigning to every point of the multishell fullerene a local dielectric tensor identical to that of graphite with its c axis aligned along the local radial direction. The dynamic, multipolar polarizabilities of the model fullerene are obtained from the exact solutions of the nonretarded Maxwell equations. The ultraviolet absorption spectrum of the hollow fullerene is calculated as a function of the ratio of the inner and outer radii. Comparisons of the theoretical absorption spectra with the 2175-Å interstellar extinction hump and with recent absorption measurements for synthetic multishell fullerenes indicate that the dielectric properties of graphite are qualitatively adequate for understanding the optical data. However, difficulties persist with both the astrophysical and laboratory absorption peaks which lead us to consider the possible role of multishell fullerene aggregation into small or large clusters. It is found that the effect of clustering is important and reduces but does not remove completely the quantitative difficulties of the graphitic multishell model. Finally theoretical electron-energy-loss spectra (EELS) of these structures with an empty or filled cavity are calculated from the multipolar polarizabilities of the model. The results indicate that spatially resolved EELS measurements should be ideally suited to study the dielectric properties of individual multishell fullerenes and to ascertain to what extent they differ from those of planar graphite.

  6. Electronic transport in smectic liquid crystals

    NASA Astrophysics Data System (ADS)

    Shiyanovskaya, I.; Singer, K. D.; Twieg, R. J.; Sukhomlinova, L.; Gettwert, V.

    2002-04-01

    Time-of-flight measurements of transient photoconductivity have revealed bipolar electronic transport in phenylnaphthalene and biphenyl liquid crystals (LC), which exhibit several smectic mesophases. In the phenylnaphthalene LC, the hole mobility is significantly higher than the electron mobility and exhibits different temperature and phase behavior. Electron mobility in the range ~10-5 cm2/V s is temperature activated and remains continuous at the phase transitions. However, hole mobility is nearly temperature independent within the smectic phases, but is very sensitive to smectic order, 10-3 cm2/V s in the smectic-B (Sm-B) and 10-4 cm2/V s in the smectic-A (Sm-A) mesophases. The different behavior for holes and electron transport is due to differing transport mechanisms. The electron mobility is apparently controlled by rate-limiting multiple shallow trapping by impurities, but hole mobility is not. To explain the lack of temperature dependence for hole mobility within the smectic phases we consider two possible polaron transport mechanisms. The first mechanism is based on the hopping of Holstein small polarons in the nonadiabatic limit. The polaron binding energy and transfer integral values, obtained from the model fit, turned out to be sensitive to the molecular order in smectic mesophases. A second possible scenario for temperature-independent hole mobility involves the competion between two different polaron mechanisms involving so-called nearly small molecular polarons and small lattice polarons. Although the extracted transfer integrals and binding energies are reasonable and consistent with the model assumptions, the limited temperature range of the various phases makes it difficult to distinguish between any of the models. In the biphenyl LCs both electron and hole mobilities exhibit temperature activated behavior in the range of 10-5 cm2/V s without sensitivity to the molecular order. The dominating transport mechanism is considered as multiple trapping

  7. Electronic transport in methylated fragments of DNA

    SciTech Connect

    Almeida, M. L. de; Oliveira, J. I. N.; Lima Neto, J. X.; Gomes, C. E. M.; Fulco, U. L. Albuquerque, E. L.; Freire, V. N.; Caetano, E. W. S.; Moura, F. A. B. F. de; Lyra, M. L.

    2015-11-16

    We investigate the electronic transport properties of methylated deoxyribonucleic-acid (DNA) strands, a biological system in which methyl groups are added to DNA (a major epigenetic modification in gene expression), sandwiched between two metallic platinum electrodes. Our theoretical simulations apply an effective Hamiltonian based on a tight-binding model to obtain current-voltage curves related to the non-methylated/methylated DNA strands. The results suggest potential applications in the development of novel biosensors for molecular diagnostics.

  8. Electronic transport in methylated fragments of DNA

    NASA Astrophysics Data System (ADS)

    de Almeida, M. L.; Oliveira, J. I. N.; Lima Neto, J. X.; Gomes, C. E. M.; Fulco, U. L.; Albuquerque, E. L.; Freire, V. N.; Caetano, E. W. S.; de Moura, F. A. B. F.; Lyra, M. L.

    2015-11-01

    We investigate the electronic transport properties of methylated deoxyribonucleic-acid (DNA) strands, a biological system in which methyl groups are added to DNA (a major epigenetic modification in gene expression), sandwiched between two metallic platinum electrodes. Our theoretical simulations apply an effective Hamiltonian based on a tight-binding model to obtain current-voltage curves related to the non-methylated/methylated DNA strands. The results suggest potential applications in the development of novel biosensors for molecular diagnostics.

  9. Electron transport fluxes in potato plateau regime

    SciTech Connect

    Shaing, K.C.; Hazeltine, R.D.

    1997-12-01

    Electron transport fluxes in the potato plateau regime are calculated from the solutions of the drift kinetic equation and fluid equations. It is found that the bootstrap current density remains finite in the region close to the magnetic axis, although it decreases with increasing collision frequency. This finite amount of the bootstrap current in the relatively collisional regime is important in modeling tokamak startup with 100{percent} bootstrap current. {copyright} {ital 1997 American Institute of Physics.}

  10. Electron ripple injection concept for transport control

    SciTech Connect

    Choe, W.; Ono, M.; Hwang, Y.S.

    1992-10-01

    Recent experiments in many devices have provided firm evidence that the edge radial electric field profile differs between L- and H-modes, and that these fields can greatly modify transport in tokamak plasmas. A nonintrusive method for inducing radial electric field based on electron ripple injection is being developed by the CDX-U group. This technique utilizes a pair of special coils to create a local magnetic field ripple to trap the electrons at the edge of the plasma. The trapped electrons then drift into the plasma due to the {del}B drift. An ECH power is applied to accelerate electrons to sufficient perpendicular energy to penetrate into the plasma. Application of ECH power to the trapped electrons should provide the desired 20 A of electron current with electrons of a few keV of energy and v{perpendicular}/v{parallel} {much_gt} 1. A controlled experiment to investigate the physics of ECH aided ripple injection has been designed on CDX-U. With the set of ripple coils designed for CDX-U, a ripple fraction of {delta} ({double_bond} {del}B/B{sub av}) {approximately} 5% is attainable. At this ripple fraction, electrons are trapped if v{perpendicular}/v{parallel} {much_gt} 1> (2{delta}){sup {minus}{1/2}} {approx}3. A resonant cavity box was fabricated for efficient heating of the trapped electrons. It is also capable of measuring the effect of the field ripple in conjunction with trapped electrons. Some preliminary results are given.

  11. Transport of electrons in monolithic hot electron Si transistors

    NASA Astrophysics Data System (ADS)

    Berz, F.

    1986-12-01

    The transport of electrons across the base of monolithic hot electron transistors is studied using a simplified model. The base is assumed to be limited by abrupt barriers and no account is taken of backscattering from the collector region. The collisions in the base are considered to be of only one type which represents an average between interactions with optical and acoustic phonons. A fundamental part in the analysis is played by the function PEX( i, x), ( i = 1, 2, …) which gives the total probability of exit into the collector of an electron whose ith collision occurs at a point of abscissa x within the base. The function PEX( i, x) is determined iteratively for decreasing values of i, using the theorem of compound probabilities, and from there the transport factor α across the base is derived. Programs have been written to this effect, and the results are illustrated by means of examples which demonstrate the effect on the transport factor α of the various parameters of the device, and show some comparisons with a previous theory[4].

  12. Enhancement of cellular uptake, transport and oral absorption of protease inhibitor saquinavir by nanocrystal formulation

    PubMed Central

    He, Yuan; Xia, Deng-ning; Li, Qiu-xia; Tao, Jin-song; Gan, Yong; Wang, Chi

    2015-01-01

    Aim: Saquinavir (SQV) is the first protease inhibitor for the treatment of HIV infection, but with poor solubility. The aim of this study was to prepare a colloidal nanocrystal suspension for improving the oral absorption of SQV. Methods: SQV nanocrystals were prepared using anti-solvent precipitation–high pressure homogenization method. The nanocrystals were characterized by a Zetasizer and transmission electron microscopy (TEM). Their dissolution, cellular uptake and transport across the human colorectal adenocarcinoma cell line (Caco-2) monolayer were investigated. Bioimaging of ex vivo intestinal sections of rats was conducted with confocal laser scanning microscopy. Pharmacokinetic analysis was performed in rats administered nanocrystal SQV suspension (50 mg/kg, ig), and the plasma SQV concentrations were measured with HPLC. Results: The SQV nanocrystals were approximately 200 nm in diameter, with a uniform size distribution. The nanocrystals had a rod-like shape under TEM. The dissolution, cellular uptake, and transport across a Caco-2 monolayer of the nanocrystal formulation were significantly improved compared to those of the coarse crystals. The ex vivo intestinal section study revealed that the fluorescently labeled nanocrystals were located in the lamina propria and the epithelium of the duodenum and jejunum. Pharmacokinetic study showed that the maximal plasma concentration (Cmax) was 2.16-fold of that for coarse crystalline SQV suspension, whereas the area under the curve (AUC) of nanocrystal SQV suspension was 1.95-fold of that for coarse crystalline SQV suspension. Conclusion: The nanocrystal drug delivery system significantly improves the oral absorption of saquinavir. PMID:26256404

  13. Conditioner for a helically transported electron beam

    SciTech Connect

    Wang, Changbiao

    1992-05-01

    The kinetic theory is developed to investigate a conditioner for a helically transported electron beam. Linear expressions for axial velocity spread are derived. Numerical simulation is used to check the theoretical results and examine nonlinear aspects of the conditioning process. The results show that in the linear regime the action of the beam conditioner on a pulsed beam mainly depends on the phase at which the beam enters the conditioner and depends only slightly on the operating wavelength. In the nonlinear regime, however, the action of the conditioner strongly depends on the operating wavelength and only slightly upon the entrance phase. For a properly chosen operating wavelength, a little less than the electron`s relativistic cyclotron wavelength, the conditioner can decrease the axial velocity spread of a pulsed beam down to less than one-third of its initial value.

  14. Electron transport parameters in NF3

    NASA Astrophysics Data System (ADS)

    Lisovskiy, V.; Yegorenkov, V.; Ogloblina, P.; Booth, J.-P.; Martins, S.; Landry, K.; Douai, D.; Cassagne, V.

    2014-03-01

    We present electron transport parameters (the first Townsend coefficient, the dissociative attachment coefficient, the fraction of electron energy lost by collisions with NF3 molecules, the average and characteristic electron energy, the electron mobility and the drift velocity) in NF3 gas calculated from published elastic and inelastic electron-NF3 collision cross-sections using the BOLSIG+ code. Calculations were performed for the combined RB (Rescigno 1995 Phys. Rev. E 52 329, Boesten et al 1996 J. Phys. B: At. Mol. Opt. Phys. 29 5475) momentum-transfer cross-section, as well as for the JB (Joucoski and Bettega 2002 J. Phys. B: At. Mol. Opt. Phys. 35 783) momentum-transfer cross-section. In addition, we have measured the radio frequency (rf) breakdown curves for various inter-electrode gaps and rfs, and from these we have determined the electron drift velocity in NF3 from the location of the turning point in these curves. These drift velocity values are in satisfactory agreement with those calculated by the BOLSIG+ code employing the JB momentum-transfer cross-section.

  15. Electronic transport in graphene-based heterostructures

    SciTech Connect

    Tan, J. Y.; Avsar, A.; Balakrishnan, J.; Taychatanapat, T.; O'Farrell, E. C. T.; Eda, G.; Castro Neto, A. H.; Koon, G. K. W.; Özyilmaz, B.; Watanabe, K.; Taniguchi, T.

    2014-05-05

    While boron nitride (BN) substrates have been utilized to achieve high electronic mobilities in graphene field effect transistors, it is unclear how other layered two dimensional (2D) crystals influence the electronic performance of graphene. In this Letter, we study the surface morphology of 2D BN, gallium selenide (GaSe), and transition metal dichalcogenides (tungsten disulfide (WS{sub 2}) and molybdenum disulfide (MoS{sub 2})) crystals and their influence on graphene's electronic quality. Atomic force microscopy analysis shows that these crystals have improved surface roughness (root mean square value of only ∼0.1 nm) compared to conventional SiO{sub 2} substrate. While our results confirm that graphene devices exhibit very high electronic mobility (μ) on BN substrates, graphene devices on WS{sub 2} substrates (G/WS{sub 2}) are equally promising for high quality electronic transport (μ ∼ 38 000 cm{sup 2}/V s at room temperature), followed by G/MoS{sub 2} (μ ∼ 10 000 cm{sup 2}/V s) and G/GaSe (μ ∼ 2200 cm{sup 2}/V s). However, we observe a significant asymmetry in electron and hole conduction in G/WS{sub 2} and G/MoS{sub 2} heterostructures, most likely due to the presence of sulphur vacancies in the substrate crystals. GaSe crystals are observed to degrade over time even under ambient conditions, leading to a large hysteresis in graphene transport making it a less suitable substrate.

  16. Electron Transport in Short Peptide Single Molecules

    NASA Astrophysics Data System (ADS)

    Cui, Jing; Brisendine, Joseph; Ng, Fay; Nuckolls, Colin; Koder, Ronald; Venkarataman, Latha

    We present a study of the electron transport through a series of short peptides using scanning tunneling microscope-based break junction method. Our work is motivated by the need to gain a better understanding of how various levels of protein structure contribute to the remarkable capacity of proteins to transport charge in biophysical processes such as respiration and photosynthesis. We focus here on short mono, di and tri-peptides, and probe their conductance when bound to gold electrodes in a native buffer environment. We first show that these peptides can bind to gold through amine, carboxyl, thiol and methyl-sulfide termini. We then focus on two systems (glycine and alanine) and show that their conductance decays faster than alkanes terminated by the same linkers. Importantly, our results show that the peptide bond is less conductive than a sigma carbon-carbon bond. This work was supported in part by NSF-DMR 1507440.

  17. Electronic transport properties of silicon clusters

    NASA Astrophysics Data System (ADS)

    Matsuura, Yukihito

    2016-02-01

    The electronic transport properties of silicon clusters were examined via theoretical calculations using the first-principles method. Additionally, p-type doping and n-type doping were analyzed by calculating conductance and current of boron- and phosphorus-doped silicon clusters. The p-type doping and n-type doping provided a new transmission peak at an energy level around the Fermi level to increase conductance. Furthermore, simultaneous boron and phosphorus doping resulted in noticeable rectifying characteristics, with the current drive in forward bias being three times higher than that in the reverse bias. A p-n junction was achieved even on a molecular scale.

  18. Inelastic electron transport in granular arrays

    SciTech Connect

    Altland, A.; Glazman, L.I.; Kamenev, A.; Meyer, J.S. . E-mail: jmeyer@mps.ohio-state.edu

    2006-11-15

    Transport properties of granular systems are governed by Coulomb blockade effects caused by the discreteness of the electron charge. We show that, in the limit of vanishing mean level spacing on the grains, the low-temperature behavior of 1d and 2d arrays is insulating at any inter-grain coupling (characterized by a dimensionless conductance g). In 2d and g >> 1, there is a sharp Berezinskii-Kosterlitz-Thouless crossover to the conducting phase at a certain temperature, T {sub BKT}. These results are obtained by applying an instanton analysis to map the conventional 'phase' description of granular arrays onto the dual 'charge' representation.

  19. Inelastic electron transport in granular arrays.

    SciTech Connect

    Altland, A.; Glazman, L. I.; Kamenev, A.; Meyer, J. S.; Materials Science Division; Univ. zu Koln; Univ. Minnesota; Ohio State Univ.

    2006-01-01

    Transport properties of granular systems are governed by Coulomb blockade effects caused by the discreteness of the electron charge. We show that, in the limit of vanishing mean level spacing on the grains, the low-temperature behavior of 1d and 2d arrays is insulating at any inter-grain coupling (characterized by a dimensionless conductance g). In 2d and g 1, there is a sharp Berezinskii-Kosterlitz-Thouless crossover to the conducting phase at a certain temperature, T{sub BKT}. These results are obtained by applying an instanton analysis to map the conventional 'phase' description of granular arrays onto the dual 'charge' representation.

  20. Electron heat transport down steep temperature gradients

    SciTech Connect

    Matte, J.P.; Virmont, J.

    1982-12-27

    Electron heat transport is studied by numerically solving the Fokker-Planck equation, with a spherical harmonic representation of the distribution function. The first two terms (f/sub 0/, f/sub 1/) suffice, even in steep temperature gradients. Deviations from the Spitzer-Haerm law appear for lambda/L/sub T/ ((mean free path)/(temperature gradient length))> or approx. =0.01, as a result of non-Maxwellian f/sub 0/. For lambda/L/sub T/> or approx. =1, the heat flux is (1/3) of the free-streaming value. In intermediate cases, a harmonic law describes well the hottest part of the plasma.

  1. Electronic transport properties of (fluorinated) metal phthalocyanine

    NASA Astrophysics Data System (ADS)

    Fadlallah, M. M.; Eckern, U.; Romero, A. H.; Schwingenschlögl, U.

    2016-01-01

    The magnetic and transport properties of the metal phthalocyanine (MPc) and F16MPc (M = Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn and Ag) families of molecules in contact with S-Au wires are investigated by density functional theory within the local density approximation, including local electronic correlations on the central metal atom. The magnetic moments are found to be considerably modified under fluorination. In addition, they do not depend exclusively on the configuration of the outer electronic shell of the central metal atom (as in isolated MPc and F16MPc) but also on the interaction with the leads. Good agreement between the calculated conductance and experimental results is obtained. For M = Ag, a high spin filter efficiency and conductance is observed, giving rise to a potentially high sensitivity for chemical sensor applications.

  2. Conditioner for a helically transported electron beam

    SciTech Connect

    Wang, Changbiao.

    1992-05-01

    The kinetic theory is developed to investigate a conditioner for a helically transported electron beam. Linear expressions for axial velocity spread are derived. Numerical simulation is used to check the theoretical results and examine nonlinear aspects of the conditioning process. The results show that in the linear regime the action of the beam conditioner on a pulsed beam mainly depends on the phase at which the beam enters the conditioner and depends only slightly on the operating wavelength. In the nonlinear regime, however, the action of the conditioner strongly depends on the operating wavelength and only slightly upon the entrance phase. For a properly chosen operating wavelength, a little less than the electron's relativistic cyclotron wavelength, the conditioner can decrease the axial velocity spread of a pulsed beam down to less than one-third of its initial value.

  3. Characterization of the Electronic Structure of Silicon Nanoparticles Using X-ray Absorption and Emission

    SciTech Connect

    Vaverka, April Susan Montoya

    2008-01-01

    Resolving open questions regarding transport in nanostructures can have a huge impact on a broad range of future technologies such as light harvesting for energy. Silicon has potential to be used in many of these applications. Understanding how the band edges of nanostructures move as a function of size, surface termination and assembly is of fundamental importance in understanding the transport properties of these materials. In this thesis work I have investigated the change in the electronic structure of silicon nanoparticle assemblies as the surface termination is changed. Nanoparticles are synthesized using a thermal evaporation technique and sizes are determined using atomic force microscopy (AFM). By passivating the particles with molecules containing alcohol groups we are able to modify the size dependent band edge shifts. Both the valence and conduction bands are measured using synchrotron based x-ray absorption spectroscopy (XAS) and soft x-ray fluorescence (SXF) techniques. Particles synthesized via recrystallization of amorphous silicon/SiO2 multilayers of thicknesses below 10 nm are also investigated using the synchrotron techniques. These samples also show quantum confinement effects but the electronic structure is different from those synthesized via evaporation methods. The total bandgap is determined for all samples measured. The origins of these differences in the electronic structures are discussed.

  4. ELECTRON MICROSCOPY OF ABSORPTION OF TRACER MATERIALS BY TOAD URINARY BLADDER EPITHELIUM.

    PubMed

    CHOI, J K

    1965-05-01

    The absorption of Thorotrast and saccharated iron oxide by the epithelium of the toad urinary bladder was studied by electron microscopy. Whether the toads were hydrated, dehydrated, or given Pitressin, no significant differences in transport of colloidal particles by epithelial cells were observed. This implies that these physiological factors had little effect on the transport of the tracer particles. Tracer particles were encountered in three types of epithelial cells which line the bladder lumen, but most frequently in the mitochondria-rich cells. Tracer materials were incorporated into the cytoplasm of epithelial cells after being adsorbed to the coating layer covering the luminal surface of the cells. In the intermediate stage (1 to 3 hours after introducing tracer) particles were present in small vesicles, tubules, and multivesicular bodies. In the later stages (up to 65 hours), the particles were more commonly seen to be densely packed within large membrane-bounded bodies which were often found near the Golgi region. These large bodies probably were formed by the fusion of small vesicles. Irrespective of the stages of absorption, no particles were found in the intercellular spaces or in the submucosa. Particles apparently did not penetrate the intercellular spaces of the epithelium beyond the level of the tight junction.

  5. Calculation tool for transported geothermal energy using two-step absorption process

    DOE Data Explorer

    Kyle Gluesenkamp

    2016-02-01

    This spreadsheet allows the user to calculate parameters relevant to techno-economic performance of a two-step absorption process to transport low temperature geothermal heat some distance (1-20 miles) for use in building air conditioning. The parameters included are (1) energy density of aqueous LiBr and LiCl solutions, (2) transportation cost of trucking solution, and (3) equipment cost for the required chillers and cooling towers in the two-step absorption approach. More information is available in the included public report: "A Technical and Economic Analysis of an Innovative Two-Step Absorption System for Utilizing Low-Temperature Geothermal Resources to Condition Commercial Buildings"

  6. Status of electron transport in MCNP{trademark}

    SciTech Connect

    Hughes, H.G.

    1995-09-01

    In recent years, an ongoing project within the radiation transport group (XTM) at Los Alamos National Laboratory has been the implementation and validation of an electron transport capability in the Monte Carlo code NICNP. In this paper the authors document the continuous-energy electron transport methods currently in use in MCNP, and describes a recent improvement of the energy-loss straggling algorithm. MCNP also supports electron transport calculations in a multigroup mode.

  7. Electronic transport of recrystallized freestanding graphene nanoribbons.

    PubMed

    Qi, Zhengqing John; Daniels, Colin; Hong, Sung Ju; Park, Yung Woo; Meunier, Vincent; Drndić, Marija; Johnson, A T Charlie

    2015-01-01

    The use of graphene and other two-dimensional materials in next-generation electronics is hampered by the significant damage caused by conventional lithographic processing techniques employed in device fabrication. To reduce the density of defects and increase mobility, Joule heating is often used since it facilitates lattice reconstruction and promotes self-repair. Despite its importance, an atomistic understanding of the structural and electronic enhancements in graphene devices enabled by current annealing is still lacking. To provide a deeper understanding of these mechanisms, atomic recrystallization and electronic transport in graphene nanoribbon (GNR) devices are investigated using a combination of experimental and theoretical methods. GNR devices with widths below 10 nm are defined and electrically measured in situ within the sample chamber of an aberration-corrected transmission electron microscope. Immediately after patterning, we observe few-layer polycrystalline GNRs with irregular sp(2)-bonded edges. Continued structural recrystallization toward a sharp, faceted edge is promoted by increasing application of Joule heat. Monte Carlo-based annealing simulations reveal that this is a result of concentrated local currents at lattice defects, which in turn promotes restructuring of unfavorable edge structures toward an atomically sharp state. We establish that intrinsic conductance doubles to 2.7 e(2)/h during the recrystallization process following an almost 3-fold reduction in device width, which is attributed to improved device crystallinity. In addition to the observation of consistent edge bonding in patterned GNRs, we further motivate the use of bonded bilayer GNRs for future nanoelectronic components by demonstrating how electronic structure can be tailored by an appropriate modification of the relative twist angle of the bonded bilayer.

  8. Ion age transport: developing devices beyond electronics

    NASA Astrophysics Data System (ADS)

    Demming, Anna

    2014-03-01

    There is more to current devices than conventional electronics. Increasingly research into the controlled movement of ions and molecules is enabling a range of new technologies. For example, as Weihua Guan, Sylvia Xin Li and Mark Reed at Yale University explain, 'It offers a unique opportunity to integrate wet ionics with dry electronics seamlessly'. In this issue they provide an overview of voltage-gated ion and molecule transport in engineered nanochannels. They cover the theory governing these systems and fabrication techniques, as well as applications, including biological and chemical analysis, and energy conversion [1]. Studying the movement of particles in nanochannels is not new. The transport of materials in rock pores led Klinkenberg to describe an analogy between diffusion and electrical conductivity in porous rocks back in 1951 [2]. And already in 1940, Harold Abramson and Manuel Gorin noted that 'When an electric current is applied across the living human skin, the skin may be considered to act like a system of pores through which transfer of substances like ragweed pollen extract may be achieved both by electrophoretic and by diffusion phenomena' [3]. Transport in living systems through pore structures on a much smaller scale has attracted a great deal of research in recent years as well. The selective transport of ions and small organic molecules across the cell membrane facilitates a number of functions including communication between cells, nerve conduction and signal transmission. Understanding these processes may benefit a wide range of potential applications such as selective separation, biochemical sensing, and controlled release and drug delivery processes. In Germany researchers have successfully demonstrated controlled ionic transport through nanopores functionalized with amine-terminated polymer brushes [4]. The polymer nanobrushes swell and shrink in response to changes in temperature, thus opening and closing the nanopore passage to ionic

  9. Ion age transport: developing devices beyond electronics

    NASA Astrophysics Data System (ADS)

    Demming, Anna

    2014-03-01

    There is more to current devices than conventional electronics. Increasingly research into the controlled movement of ions and molecules is enabling a range of new technologies. For example, as Weihua Guan, Sylvia Xin Li and Mark Reed at Yale University explain, 'It offers a unique opportunity to integrate wet ionics with dry electronics seamlessly'. In this issue they provide an overview of voltage-gated ion and molecule transport in engineered nanochannels. They cover the theory governing these systems and fabrication techniques, as well as applications, including biological and chemical analysis, and energy conversion [1]. Studying the movement of particles in nanochannels is not new. The transport of materials in rock pores led Klinkenberg to describe an analogy between diffusion and electrical conductivity in porous rocks back in 1951 [2]. And already in 1940, Harold Abramson and Manuel Gorin noted that 'When an electric current is applied across the living human skin, the skin may be considered to act like a system of pores through which transfer of substances like ragweed pollen extract may be achieved both by electrophoretic and by diffusion phenomena' [3]. Transport in living systems through pore structures on a much smaller scale has attracted a great deal of research in recent years as well. The selective transport of ions and small organic molecules across the cell membrane facilitates a number of functions including communication between cells, nerve conduction and signal transmission. Understanding these processes may benefit a wide range of potential applications such as selective separation, biochemical sensing, and controlled release and drug delivery processes. In Germany researchers have successfully demonstrated controlled ionic transport through nanopores functionalized with amine-terminated polymer brushes [4]. The polymer nanobrushes swell and shrink in response to changes in temperature, thus opening and closing the nanopore passage to ionic

  10. Electronic transport and dynamics in correlated heterostructures

    NASA Astrophysics Data System (ADS)

    Mazza, G.; Amaricci, A.; Capone, M.; Fabrizio, M.

    2015-05-01

    We investigate by means of the time-dependent Gutzwiller approximation the transport properties of a strongly correlated slab subject to Hubbard repulsion and connected with to two metallic leads kept at a different electrochemical potential. We focus on the real-time evolution of the electronic properties after the slab is connected to the leads and consider both metallic and Mott insulating slabs. When the correlated slab is metallic, the system relaxes to a steady state that sustains a finite current. The zero-bias conductance is finite and independent of the degree of correlations within the slab as long as the system remains metallic. On the other hand, when the slab is in a Mott insulating state, the external bias leads to currents that are exponentially activated by charge tunneling across the Mott-Hubbard gap, consistent with the Landau-Zener dielectric breakdown scenario.

  11. Simultaneous enhancements in photon absorption and charge transport of bismuth vanadate photoanodes for solar water splitting

    PubMed Central

    Kim, Tae Woo; Ping, Yuan; Galli, Giulia A.; Choi, Kyoung-Shin

    2015-01-01

    n-Type bismuth vanadate has been identified as one of the most promising photoanodes for use in a water-splitting photoelectrochemical cell. The major limitation of BiVO4 is its relatively wide bandgap (∼2.5 eV), which fundamentally limits its solar-to-hydrogen conversion efficiency. Here we show that annealing nanoporous bismuth vanadate electrodes at 350 °C under nitrogen flow can result in nitrogen doping and generation of oxygen vacancies. This gentle nitrogen treatment not only effectively reduces the bandgap by ∼0.2 eV but also increases the majority carrier density and mobility, enhancing electron–hole separation. The effect of nitrogen incorporation and oxygen vacancies on the electronic band structure and charge transport of bismuth vanadate are systematically elucidated by ab initio calculations. Owing to simultaneous enhancements in photon absorption and charge transport, the applied bias photon-to-current efficiency of nitrogen-treated BiVO4 for solar water splitting exceeds 2%, a record for a single oxide photon absorber, to the best of our knowledge. PMID:26498984

  12. Effects of Cu deficiency on photosynthetic electron transport

    SciTech Connect

    Droppa, M.; Terry, N.; Horvath, G.

    1984-04-01

    The role of copper (Cu) in photosynthetic electron transport was explored by using Cu deficiency in sugar beet as an experimental approach. Copper influenced electron transport at two sites in addition to plastocyanin. Under mild deficiency (0.84 nmol of Cu per cm/sup 2/ of leaf area), electron transport between the two photosystems (PS) is inhibited but not electron transport within PS I or PS II measured separately. The chlorophyll/plastoquinone ratio was normal in Cu-deficient plants. However, the breakpoint in the Arrhenius plot of electron transport was shifted towards a higher temperature. It is concluded that Cu is necessary to maintain the appropriate membrane fluidity to ensure the mobility of plastoquinone molecules to transfer electrons between the two photosystems. Under severe deficiency (0.22 nmol of Cu per cm/sup 2/ of leaf area) both PS II and PS I electron transports were inhibited and to the same extent. PS II electron transport activity could not be restored by adding artifical electron donors. Polypeptides with M/sub r/s of 28,000 and 13,500 were missing in Cu-deficient chloroplast membranes. In PS II particles prepared from normal chloroplasts of spinach, 2 atoms of Cu per reaction center are present. We conclude that Cu influences PS II electron transport either directly, by participation in electron transfer as a constituent of an electron carrier, or indirectly, via the polypeptide composition of the membrane in the PS II complex.

  13. Electron scattering and transport in liquid argon

    SciTech Connect

    Boyle, G. J.; Cocks, D. G.; White, R. D.; McEachran, R. P.

    2015-04-21

    The transport of excess electrons in liquid argon driven out of equilibrium by an applied electric field is revisited using a multi-term solution of Boltzmann’s equation together with ab initio liquid phase cross-sections calculated using the Dirac-Fock scattering equations. The calculation of liquid phase cross-sections extends previous treatments to consider multipole polarisabilities and a non-local treatment of exchange, while the accuracy of the electron-argon potential is validated through comparison of the calculated gas phase cross-sections with experiment. The results presented highlight the inadequacy of local treatments of exchange that are commonly used in liquid and cluster phase cross-section calculations. The multi-term Boltzmann equation framework accounting for coherent scattering enables the inclusion of the full anisotropy in the differential cross-section arising from the interaction and the structure factor, without an a priori assumption of quasi-isotropy in the velocity distribution function. The model, which contains no free parameters and accounts for both coherent scattering and liquid phase screening effects, was found to reproduce well the experimental drift velocities and characteristic energies.

  14. Vibrationally dependent electron-electron interactions in resonant electron transport through single-molecule junctions

    NASA Astrophysics Data System (ADS)

    Erpenbeck, A.; Härtle, R.; Bockstedte, M.; Thoss, M.

    2016-03-01

    We investigate the role of electronic-vibrational coupling in resonant electron transport through single-molecule junctions, taking into account that the corresponding coupling strengths may depend on the charge and excitation state of the molecular bridge. Within an effective-model Hamiltonian approach for a molecule with multiple electronic states, this requires to extend the commonly used model and include vibrationally dependent electron-electron interaction. We use Born-Markov master equation methods and consider selected models to exemplify the effect of the additional interaction on the transport characteristics of a single-molecule junction. In particular, we show that it has a significant influence on local cooling and heating mechanisms, it may result in negative differential resistance, and it may cause pronounced asymmetries in the conductance map of a single-molecule junction.

  15. Study of electron transition energies between anions and cations in spinel ferrites using differential UV-vis absorption spectra

    NASA Astrophysics Data System (ADS)

    Xue, L. C.; Wu, L. Q.; Li, S. Q.; Li, Z. Z.; Tang, G. D.; Qi, W. H.; Ge, X. S.; Ding, L. L.

    2016-07-01

    It is very important to determine electron transition energies (Etr) between anions and different cations in order to understand the electrical transport and magnetic properties of a material. Many authors have analyzed UV-vis absorption spectra using the curve (αhν)2 vs E, where α is the absorption coefficient and E(=hν) is the photon energy. Such an approach can give only two band gap energies for spinel ferrites. In this paper, using differential UV-vis absorption spectra, dα/dE vs E, we have obtained electron transition energies (Etr) between the anions and cations, Fe2+ and Fe3+ at the (A) and [B] sites and Ni2+ at the [B] sites for the (A)[B]2O4 spinel ferrite samples CoxNi0.7-xFe2.3O4 (0.0≤x≤0.3), CrxNi0.7Fe2.3-xO4 (0.0≤x≤0.3) and Fe3O4. We suggest that the differential UV-vis absorption spectra should be accepted as a general analysis method for determining electron transition energies between anions and cations.

  16. Laser damage in silicon: Energy absorption, relaxation, and transport

    SciTech Connect

    Rämer, A. Rethfeld, B.; Osmani, O.

    2014-08-07

    Silicon irradiated with an ultrashort 800 nm-laser pulse is studied theoretically using a two temperature description that considers the transient free carrier density during and after irradiation. A Drude model is implemented to account for the highly transient optical parameters. We analyze the importance of considering these density-dependent parameters as well as the choice of the Drude collision frequency. In addition, degeneracy and transport effects are investigated. The importance of each of these processes for resulting calculated damage thresholds is studied. We report damage thresholds calculations that are in very good agreement with experimental results over a wide range of pulse durations.

  17. Quantum mechanical study of the coupling of plasmon excitations to atomic-scale electron transport

    SciTech Connect

    Song Peng; Nordlander, Peter; Gao Shiwu

    2011-02-21

    The coupling of optical excitation and electron transport through a sodium atom in a plasmonic dimer junction is investigated using time-dependent density functional theory. The optical absorption and dynamic conductance is determined as a function of gap size. Surface plasmons are found to couple to atomic-scale transport through several different channels including dipolar, multipolar, and charge transfer plasmon modes. These findings provide insight into subnanoscale couplings of plasmons and atoms, a subject of general interest in plasmonics and molecular electronics.

  18. The effects of excipients on transporter mediated absorption.

    PubMed

    Goole, Jonathan; Lindley, David J; Roth, Wyatt; Carl, Stephen M; Amighi, Karim; Kauffmann, Jean-Michel; Knipp, Gregory T

    2010-06-30

    Traditionally most pharmaceutical excipients used for peroral dosage forms have been considered to be inert, although they have been known to play an important role in governing the release of the active pharmaceutical ingredient (API) required for the desired therapeutic effect. Of considerable interest is the emerging data demonstrating that many of these "inert" excipients may produce subtle changes that could directly or indirectly alter the activity of membrane-spanning proteins such as transporters. In this way, excipients could be altering the overall ADMET properties of an incorporated drug thereby affecting its intended therapeutic efficacy and/or enhancing adverse side effects. Therefore, given this recent evidence, it seems necessary to review what has been reported in the literature on interactions of excipients with human physiological entities, particularly transporters. As of today, safety/toxicity evaluations are typically based on the appearance of gross morphological changes rather than the effects on a cellular level, the ability of excipients in modifying the pharmacological activity of an active drug could lead to toxicity evaluation in routine for each additive used in oral formulations. Further knowledge on this subject will enable formulators to make more rational decisions in dosage form design and will help answer the question of whether certain excipients should be considered active pharmaceutical components of formulations. PMID:20417699

  19. Designing a beam transport system for RHIC's electron lens

    SciTech Connect

    Gu, X.; Pikin, A.; Okamura, M.; Fischer, W.; Luo, Y.; Gupta, R.; Hock, J.; Raparia, D.

    2011-03-28

    We designed two electron lenses to apply head-on beam-beam compensation for RHIC; they will be installed near IP10. The electron-beam transport system is an important subsystem of the entire electron-lens system. Electrons are transported from the electron gun to the main solenoid and further to the collector. The system must allow for changes of the electron beam size inside the superconducting magnet, and for changes of the electron position by 5 mm in the horizontal- and vertical-planes.

  20. Transition in Electron Transport in a Cylindrical Hall Thruster

    SciTech Connect

    J.B. Parker, Y. Raitses, and N.J. Fisch

    2010-06-02

    Through the use of high-speed camera and Langmuir probe measurements in a cylindrical Hall thruster, we report the discovery of a rotating spoke of increased plasma density and light emission which correlates with increased electron transport across the magnetic field. As cathode electron emission is increased, a sharp transition occurs where the spoke disappears and electron transport decreases. This suggests that a significant fraction of the electron current might be directed through the spoke.

  1. Transition in electron transport in a cylindrical Hall thruster

    SciTech Connect

    Parker, J. B.; Raitses, Y.; Fisch, N. J.

    2010-08-30

    Through the use of high-speed camera and Langmuir probe measurements in a cylindrical Hall thruster, we report the discovery of a rotating spoke of increased plasma density and light emission which correlates with increased electron transport across the magnetic field. As cathode electron emission is increased, a sharp transition occurs where the spoke disappears and electron transport decreases. This suggests that a significant fraction of the electron current might be directed through the spoke.

  2. Electronic and Ionic Transport Dynamics in Organolead Halide Perovskites.

    PubMed

    Li, Dehui; Wu, Hao; Cheng, Hung-Chieh; Wang, Gongming; Huang, Yu; Duan, Xiangfeng

    2016-07-26

    Ion migration has been postulated as the underlying mechanism responsible for the hysteresis in organolead halide perovskite devices. However, the electronic and ionic transport dynamics and how they impact each other in organolead halide perovskites remain elusive to date. Here we report a systematic investigation of the electronic and ionic transport dynamics in organolead halide perovskite microplate crystals and thin films using temperature-dependent transient response measurements. Our study reveals that thermally activated ionic and electronic conduction coexist in perovskite devices. The extracted activation energies suggest that the electronic transport is easier, but ions migrate harder in microplates than in thin films, demonstrating that the crystalline quality and grain boundaries can fundamentally modify electronic and ionic transport in perovskites. These findings offer valuable insight on the electronic and ionic transport dynamics in organolead halide perovskites, which is critical for optimizing perovskite devices with reduced hysteresis and improved stability and efficiency.

  3. The induction of microsomal electron transport enzymes.

    PubMed

    Waterman, M R; Estabrook, R W

    1983-01-01

    Liver endoplasmic reticulum contains as NADPH-dependent electron transport complex where the family of hemeproteins, termed cytochrome P-450, serve as catalysts for the oxidation of a variety of different organic chemicals. The content and inventory of the types of cytochrome P-450 is readily modified following in vivo treatment of animals with 'inducing agents' such as barbiturates, steroids and polycyclic hydrocarbons. Recent studies have applied the methods of molecular biology to evaluate changes in the transcription and translation of genomic information occurring concomitant with the initiation of synthesis of various types of cytochrome P-450. The ability to isolate unique cytochrome P-450 proteins and to prepare specific antibodies now permits the study of in vitro translation of mRNA and the preparation of specific cDNAs. The present review summarizes the historic background leading to current concepts of cytochrome P-450 induction and describes recent advances in our knowledge of the regulation of cytochrome P-450 synthesis in the liver. PMID:6353196

  4. Twin-peaks absorption spectra of excess electron in ionic liquids

    NASA Astrophysics Data System (ADS)

    Musat, Raluca M.; Kondoh, Takafumi; Yoshida, Yoichi; Takahashi, Kenji

    2014-07-01

    The solvated electron in room temperature ionic liquids (RTILs) has been the subject of several investigations and several reports exist on its nature and absorption spectrum. These studies concluded that the solvated electron exhibits an absorption spectrum peaking in the 1000-1400 nm region; a second absorption band peaking in the UV region has been assigned to the hole or dication radicals simultaneously formed in the system. Here we report on the fate of the excess electron in the ionic liquid 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide, P14+/NTf2- using nanosecond pulse radiolysis. Scavenging experiments allowed us to record and disentangle the complex spectrum measured in P14+/NTf2-. We identified a bi-component absorption spectrum, due to the solvated electron, the absorption maxima located at 1080 nm and around 300 nm, as predicted by previous ab-initio molecular dynamics simulations for the dry excess electron. We also measured the spectra using different ionic liquids and confirmed the same feature of two absorption peaks. The present results have important implications for the characterization of solvated electrons in ionic liquids and better understanding of their structure and reactivity.

  5. The tunable electronic structure and optic absorption properties of phosphorene by a normally applied electric field

    NASA Astrophysics Data System (ADS)

    Yang, Mou; Duan, Hou-Jian; Wang, Rui-Qiang

    2016-10-01

    We studied the electronic structure and optical absorption properties of phosphorene (a monolayer black phosphorus) under a normally applied electric field. The electric field enlarges the energy gap, weakens the effective mass anisotropy, and increases the effective mass component along the armchair direction (x-direction) for both conduction and valence bands but provides little change to the component along the zigzag direction (y-direction). The band edge optical absorption is completely polarized in the x-direction, and decreases when increasing the electric field. If the exciting frequency is beyond the energy gap, the absorption for the y-polarized light becomes nonzero, but the absorption is still highly polarized.

  6. Absorption of infrared radiation by electrons in the field of a neutral hydrogen atom

    NASA Technical Reports Server (NTRS)

    Stallcop, J. R.

    1974-01-01

    An analytical expression for the absorption coefficient is developed from a relationship between the cross-section for inverse bremsstrahlung absorption and the cross-section for electron-atom momentum transfer; it is accurate for those photon frequencies v and temperatures such that hv/kT is small. The determination of the absorption of infrared radiation by free-free transitions of the negative hydrogen ion has been extended to higher temperatures. A simple analytical expression for the absorption coefficient has been derived.

  7. Enhanced carrier collection efficiency and reduced quantum state absorption by electron doping in self-assembled quantum dot solar cells

    SciTech Connect

    Li, Tian E-mail: dage@ece.umd.edu; Dagenais, Mario E-mail: dage@ece.umd.edu; Lu, Haofeng; Fu, Lan; Tan, Hark Hoe; Jagadish, Chennupati

    2015-02-02

    Reduced quantum dot (QD) absorption due to state filling effects and enhanced electron transport in doped QDs are demonstrated to play a key role in solar energy conversion. Reduced QD state absorption with increased n-doping is observed in the self-assembled In{sub 0.5}Ga{sub 0.5}As/GaAs QDs from high resolution below-bandgap external quantum efficiency (EQE) measurement, which is a direct consequence of the Pauli exclusion principle. We also show that besides partial filling of the quantum states, electron-doping produces negatively charged QDs that exert a repulsive Coulomb force on the mobile electrons, thus altering the electron trajectory and reducing the probability of electron capture, leading to an improved collection efficiency of photo-generated carriers, as indicated by an absolute above-bandgap EQE measurement. The resulting redistribution of the mobile electron in the planar direction is further validated by the observed photoluminescence intensity dependence on doping.

  8. Transport, metabolism, and endosomal trafficking-dependent regulation of intestinal fructose absorption.

    PubMed

    Patel, Chirag; Douard, Veronique; Yu, Shiyan; Gao, Nan; Ferraris, Ronaldo P

    2015-09-01

    Dietary fructose that is linked to metabolic abnormalities can up-regulate its own absorption, but the underlying regulatory mechanisms are not known. We hypothesized that glucose transporter (GLUT) protein, member 5 (GLUT5) is the primary fructose transporter and that fructose absorption via GLUT5, metabolism via ketohexokinase (KHK), as well as GLUT5 trafficking to the apical membrane via the Ras-related protein-in-brain 11 (Rab11)a-dependent endosomes are each required for regulation. Introducing fructose but not lysine and glucose solutions into the lumen increased by 2- to 10-fold the heterogeneous nuclear RNA, mRNA, protein, and activity levels of GLUT5 in adult wild-type mice consuming chow. Levels of GLUT5 were >100-fold that of candidate apical fructose transporters GLUTs 7, 8, and 12 whose expression, and that of GLUT 2 and the sodium-dependent glucose transporter protein 1 (SGLT1), was not regulated by luminal fructose. GLUT5-knockout (KO) mice exhibited no facilitative fructose transport and no compensatory increases in activity and expression of SGLT1 and other GLUTs. Fructose could not up-regulate GLUT5 in GLUT5-KO, KHK-KO, and intestinal epithelial cell-specific Rab11a-KO mice. The fructose-specific metabolite glyceraldehyde did not increase GLUT5 expression. GLUT5 is the primary transporter responsible for facilitative absorption of fructose, and its regulation specifically requires fructose uptake and metabolism and normal GLUT5 trafficking to the apical membrane.

  9. Low temperature charge transport and microwave absorption of carbon coated iron nanoparticles–polymer composite films

    SciTech Connect

    Prasad, V.

    2012-06-15

    Highlights: ► Carbon coated Fe nanoparticle–PVC composite films were prepared by solution casting method. ► A low electrical percolation threshold of 2.2 was achieved. ► The low temperature electrical conductivity follows variable range hopping type conduction. ► An EMI shielding of 18 dB was achieved in 200 micron thick film. -- Abstract: In this paper, the low temperature electrical conductivity and microwave absorption properties of carbon coated iron nanoparticles–polyvinyl chloride composite films are investigated for different filler fractions. The filler particles are prepared by the pyrolysis of ferrocene at 980 °C and embedded in polyvinyl chloride matrix. The high resolution transmission electron micrographs of the filler material have shown a 5 nm thin layer graphitic carbon covering over iron particles. The room temperature electrical conductivity of the composite film changes by 10 orders of magnitude with the increase of filler concentration. A percolation threshold of 2.2 and an electromagnetic interference shielding efficiency (EMI SE) of ∼18.6 dB in 26.5–40 GHz range are observed for 50 wt% loading. The charge transport follows three dimensional variable range hopping conduction.

  10. Electron transport theory in magnetic nanostructures

    NASA Astrophysics Data System (ADS)

    Choy, Tat-Sang

    Magnetic nanostructure has been a new trend because of its application in making magnetic sensors, magnetic memories, and magnetic reading heads in hard disks drives. Although a variety of nanostructures have been realized in experiments in recent years by innovative sample growth techniques, the theoretical study of these devices remain a challenge. On one hand, atomic scale modeling is often required for studying the magnetic nanostructures; on the other, these structures often have a dimension on the order of one micrometer, which makes the calculation numerically intensive. In this work, we have studied the electron transport theory in magnetic nanostructures, with special attention to the giant magnetoresistance (GMR) structure. We have developed a model that includes the details of the band structure and disorder, both of which are both important in obtaining the conductivity. We have also developed an efficient algorithm to compute the conductivity in magnetic nanostructures. The model and the algorithm are general and can be applied to complicated structures. We have applied the theory to current-perpendicular-to-plane GMR structures and the results agree with experiments. Finally, we have searched for the atomic configuration with the highest GMR using the simulated annealing algorithm. This method is computationally intensive because we have to compute the GMR for 103 to 104 configurations. However it is still very efficient because the number of steps it takes to find the maximum is much smaller than the number of all possible GMR structures. We found that ultra-thin NiCu superlattices have surprisingly large GMR even at the moderate disorder in experiments. This finding may be useful in improving the GMR technology.

  11. Reverse electron transport effects on NADH formation and metmyoglobin reduction.

    PubMed

    Belskie, K M; Van Buiten, C B; Ramanathan, R; Mancini, R A

    2015-07-01

    The objective was to determine if NADH generated via reverse electron flow in beef mitochondria can be used for electron transport-mediated reduction and metmyoglobin reductase pathways. Beef mitochondria were isolated from bovine hearts (n=5) and reacted with combinations of succinate, NAD, and mitochondrial inhibitors to measure oxygen consumption and NADH formation. Mitochondria and metmyoglobin were reacted with succinate, NAD, and mitochondrial inhibitors to measure electron transport-mediated metmyoglobin reduction and metmyoglobin reductase activity. Addition of succinate and NAD increased oxygen consumption, NADH formation, electron transport-mediated metmyoglobin reduction, and reductase activity (p<0.05). Addition of antimycin A prevented electron flow beyond complex III, therefore, decreasing oxygen consumption and electron transport-mediated metmyoglobin reduction. Addition of rotenone prevented reverse electron flow, increased oxygen consumption, increased electron transport-mediated metmyoglobin reduction, and decreased NADH formation. Succinate and NAD can generate NADH in bovine tissue postmortem via reverse electron flow and this NADH can be used by both electron transport-mediated and metmyoglobin reductase pathways. PMID:25828162

  12. Reverse electron transport effects on NADH formation and metmyoglobin reduction.

    PubMed

    Belskie, K M; Van Buiten, C B; Ramanathan, R; Mancini, R A

    2015-07-01

    The objective was to determine if NADH generated via reverse electron flow in beef mitochondria can be used for electron transport-mediated reduction and metmyoglobin reductase pathways. Beef mitochondria were isolated from bovine hearts (n=5) and reacted with combinations of succinate, NAD, and mitochondrial inhibitors to measure oxygen consumption and NADH formation. Mitochondria and metmyoglobin were reacted with succinate, NAD, and mitochondrial inhibitors to measure electron transport-mediated metmyoglobin reduction and metmyoglobin reductase activity. Addition of succinate and NAD increased oxygen consumption, NADH formation, electron transport-mediated metmyoglobin reduction, and reductase activity (p<0.05). Addition of antimycin A prevented electron flow beyond complex III, therefore, decreasing oxygen consumption and electron transport-mediated metmyoglobin reduction. Addition of rotenone prevented reverse electron flow, increased oxygen consumption, increased electron transport-mediated metmyoglobin reduction, and decreased NADH formation. Succinate and NAD can generate NADH in bovine tissue postmortem via reverse electron flow and this NADH can be used by both electron transport-mediated and metmyoglobin reductase pathways.

  13. Transport, metabolism, and endosomal trafficking-dependent regulation of intestinal fructose absorption

    PubMed Central

    Patel, Chirag; Douard, Veronique; Yu, Shiyan; Gao, Nan; Ferraris, Ronaldo P.

    2015-01-01

    Dietary fructose that is linked to metabolic abnormalities can up-regulate its own absorption, but the underlying regulatory mechanisms are not known. We hypothesized that glucose transporter (GLUT) protein, member 5 (GLUT5) is the primary fructose transporter and that fructose absorption via GLUT5, metabolism via ketohexokinase (KHK), as well as GLUT5 trafficking to the apical membrane via the Ras-related protein-in-brain 11 (Rab11)a-dependent endosomes are each required for regulation. Introducing fructose but not lysine and glucose solutions into the lumen increased by 2- to 10-fold the heterogeneous nuclear RNA, mRNA, protein, and activity levels of GLUT5 in adult wild-type mice consuming chow. Levels of GLUT5 were >100-fold that of candidate apical fructose transporters GLUTs 7, 8, and 12 whose expression, and that of GLUT 2 and the sodium-dependent glucose transporter protein 1 (SGLT1), was not regulated by luminal fructose. GLUT5-knockout (KO) mice exhibited no facilitative fructose transport and no compensatory increases in activity and expression of SGLT1 and other GLUTs. Fructose could not up-regulate GLUT5 in GLUT5-KO, KHK-KO, and intestinal epithelial cell-specific Rab11a-KO mice. The fructose-specific metabolite glyceraldehyde did not increase GLUT5 expression. GLUT5 is the primary transporter responsible for facilitative absorption of fructose, and its regulation specifically requires fructose uptake and metabolism and normal GLUT5 trafficking to the apical membrane.—Patel, C., Douard, V., Yu, S., Gao, N., Ferraris, R. P. Transport, metabolism, and endosomal trafficking-dependent regulation of intestinal fructose absorption. PMID:26071406

  14. The absorption jump factor of effective atomic number and electronic density for some barium compounds

    NASA Astrophysics Data System (ADS)

    Polat, Recep; Yalçın, Zeynel; İçelli, Orhan

    2011-02-01

    Some photonic energy absorption parameters such as the mass attenuation coefficient μt, the molecular σM, atomic σA, the electronic cross-sections σE, the effective atomic number Zeff and the electron density NE have been calculated and measured. We have gained the terms jump factor of effective atomic number JZeff and jump factor of electronic density JNE to literature with the help of these fundamental parameters. Also, we want to obtain both XAFS effect and the applicability of mixture rule. The most interesting finding in this study is that the trend of the total molecular, atomic and electronic cross-sections is getting beyond the measure by the absorption edge and these cross-sections are affected in the region of absorption edge. The obtained results have been compared with some other theoretical values given earlier.

  15. Thermally activated long range electron transport in living biofilms.

    PubMed

    Yates, Matthew D; Golden, Joel P; Roy, Jared; Strycharz-Glaven, Sarah M; Tsoi, Stanislav; Erickson, Jeffrey S; El-Naggar, Mohamed Y; Calabrese Barton, Scott; Tender, Leonard M

    2015-12-28

    Microbial biofilms grown utilizing electrodes as metabolic electron acceptors or donors are a new class of biomaterials with distinct electronic properties. Here we report that electron transport through living electrode-grown Geobacter sulfurreducens biofilms is a thermally activated process with incoherent redox conductivity. The temperature dependency of this process is consistent with electron-transfer reactions involving hemes of c-type cytochromes known to play important roles in G. sulfurreducens extracellular electron transport. While incoherent redox conductivity is ubiquitous in biological systems at molecular-length scales, it is unprecedented over distances it appears to occur through living G. sulfurreducens biofilms, which can exceed 100 microns in thickness. PMID:26611733

  16. In vitro study of transporters involved in intestinal absorption of inorganic arsenic.

    PubMed

    Calatayud, Marta; Barrios, Julio A; Vélez, Dinoraz; Devesa, Vicenta

    2012-02-20

    Inorganic arsenic (iAs) [As(III)+As(V)] is a drinking water contaminant, and human exposure to these arsenic species has been linked with a wide range of health effects. The main path of exposure is the oral route, and the intestinal epithelium is the first physiological barrier that iAs must cross in order to be absorbed. However, there is a lack of information about intestinal iAs absorption. The aim of this study was to evaluate the participation of certain transporters [glucose transporters (GLUT and SGLT), organic anion transporting polypeptides (OATPs), aquaporins (AQPs), and phosphate transporters (NaPi and PiT)] in intestinal absorption of As(V) and As(III), using the Caco-2 cell line as a model of the intestinal epithelium. For this purpose, the effects of chemical inhibition and gene silencing of the transporters of interest on iAs uptake were evaluated, and also the differential expression of these transporters after treatment with iAs. The results show that chemical inhibition using rifamycin SV (OATP inhibitor), phloridzin (SGLT inhibitor), phloretin (GLUT and AQP inhibitor), and copper sulfate (AQP inhibitor) leads to a significant reduction in the apparent permeability and cellular retention of As(III). RT-qPCR indicates up-regulation of GLUT2, GLUT5, OATPB, AQP3, and AQP10 after exposure to As(III), while exposure to As(V) increases the expression of sodium-dependent phosphate transporters, especially NaPiIIb. Gene silencing of OATPB, AQP10, and GLUT5 for As(III) and NaPiIIb for As(V) significantly reduces uptake of the inorganic forms. These results indicate that these transporters may be involved in intestinal absorption of iAs.

  17. Ultrafast electronic transport in low dimensional semiconductor nanostructures

    NASA Astrophysics Data System (ADS)

    Choi, Hyunyong; Norris, Theodore B.; Faist, Jérôme; Capasso, Federico

    2009-02-01

    Ultrafast time-resolved pump-probe measurements are used to study low energy excitations and dynamics of electronic transport in various semiconductor nanostructures. In quantum cascade lasers, we observe ultrafast gain recovery dynamics due to electronic transport in the structures. In particular, the nature of electronic transport had been addressed by using ultrafast optical techniques. Sub-picosecond resonant tunneling injection from the quantum cascade laser injector ground state into the upper lasing state was found to be incoherent due to strong dephasing in the active subband. We also observed the strong coupling of the electronic transport to the intra-cavity photon density, which we term "photon-driven transport". Note that this invited paper reviews the details of our recent observations (H. Choi et al., Phys. Rev. Lett., 100, 167401, 2008 and H. Choi, et al., Appl. Phys. Lett. 92, 122114 (2008)).

  18. Electronic absorption spectrum of triacetylene cation for astronomical considerations.

    PubMed

    Chakrabarty, S; Rice, C A; Mazzotti, F J; Dietsche, R; Maier, J P

    2013-10-01

    The A(2)Πg ← X(2)Πu electronic transition (4800-6000 Å) of triacetylene cation was measured in an ion trap, where the vibrational and rotational degrees of freedom were equilibrated to 25 K. The rotational profile of the origin band is predicted by a collisional-radiative rate model under conditions expected in diffuse interstellar clouds. Variation in the density of the surrounding gas, rotational temperature, and velocity dispersion are taken into account.

  19. Kinetic theory of transport processes in partially ionized reactive plasma, II: Electron transport properties

    NASA Astrophysics Data System (ADS)

    Zhdanov, V. M.; Stepanenko, A. A.

    2016-11-01

    The previously obtained in (Zhdanov and Stepanenko, 2016) general transport equations for partially ionized reactive plasma are employed for analysis of electron transport properties in molecular and atomic plasmas. We account for both elastic and inelastic interaction channels of electrons with atoms and molecules of plasma and also the processes of electron impact ionization of neutral particles and three-body ion-electron recombination. The system of scalar transport equations for electrons is discussed and the expressions for non-equilibrium corrections to electron ionization and recombination rates and the diagonal part of the electron pressure tensor are derived. Special attention is paid to analysis of electron energy relaxation during collisions with plasma particles having internal degrees of freedom and the expression for the electron coefficient of inelastic energy losses is deduced. We also derive the expressions for electron vector and tensorial transport fluxes and the corresponding transport coefficients for partially ionized reactive plasma, which represent a generalization of the well-known results obtained by Devoto (1967). The results of numerical evaluation of contribution from electron inelastic collisions with neutral particles to electron transport properties are presented for a series of molecular and atomic gases.

  20. Theoretical analysis of electronic absorption spectra of vitamin B12 models

    NASA Astrophysics Data System (ADS)

    Andruniow, Tadeusz; Kozlowski, Pawel M.; Zgierski, Marek Z.

    2001-10-01

    Time-dependent density-functional theory (TD-DFT) is applied to analyze the electronic absorption spectra of vitamin B12. To accomplish this two model systems were considered: CN-[CoIII-corrin]-CN (dicyanocobinamide, DCC) and imidazole-[CoIII-corrin]-CN (cyanocobalamin, ImCC). For both models 30 lowest excited states were calculated together with transition dipole moments. When the results of TD-DFT calculations were directly compared with experiment it was found that the theoretical values systematically overestimate experimental data by approximately 0.5 eV. The uniform adjustment of the calculated transition energies allowed detailed analysis of electronic absorption spectra of vitamin B12 models. All absorption bands in spectral range 2.0-5.0 eV were readily assigned. In particular, TD-DFT calculations were able to explain the origin of the shift of the lowest absorption band caused by replacement of the-CN axial ligand by imidazole.

  1. Spin transport in tilted electron vortex beams

    NASA Astrophysics Data System (ADS)

    Basu, Banasri; Chowdhury, Debashree

    2014-12-01

    In this paper we have enlightened the spin related issues of tilted Electron vortex beams. We have shown that in the skyrmionic model of electron we can have the spin Hall current considering the tilted type of electron vortex beam. We have considered the monopole charge of the tilted vortex as time dependent and through the time variation of the monopole charge we can explain the spin Hall effect of electron vortex beams. Besides, with an external magnetic field we can have a spin filter configuration.

  2. Spin transport in tilted electron vortex beams

    SciTech Connect

    Basu, Banasri; Chowdhury, Debashree

    2014-12-10

    In this paper we have enlightened the spin related issues of tilted Electron vortex beams. We have shown that in the skyrmionic model of electron we can have the spin Hall current considering the tilted type of electron vortex beam. We have considered the monopole charge of the tilted vortex as time dependent and through the time variation of the monopole charge we can explain the spin Hall effect of electron vortex beams. Besides, with an external magnetic field we can have a spin filter configuration.

  3. Tuning anisotropic electronic transport properties of phosphorene via substitutional doping.

    PubMed

    Guo, Caixia; Xia, Congxin; Fang, Lizhen; Wang, Tianxing; Liu, Yufang

    2016-10-01

    Using first-principles calculations, we studied the anisotropic electronic transport properties of pristine and X-doped phosphorene (X = B, Al, Ga, C, Si, Ge, N, As, O, S, and Se atoms). The results show that doping different elements can induce obviously different electronic transport characteristics. Moreover, isovalent doping maintains semiconducting characteristics and anisotropic transport properties, while group IV and VI atoms doping can induce metal properties. Meanwhile, Al and Ga substituting P decrease the anisotropic behaviors of transport, and other atom doping still preserves anisotropic characteristics. Interestingly, obvious negative differential resistance behaviors can be observed in C, Si, Ge, O, S, and Se-doped phosphorene.

  4. Terahertz electromodulation spectroscopy of electron transport in GaN

    SciTech Connect

    Engelbrecht, S. G.; Arend, T. R.; Kersting, R.; Zhu, T.; Kappers, M. J.

    2015-03-02

    Time-resolved terahertz (THz) electromodulation spectroscopy is applied to investigate the high-frequency transport of electrons in gallium nitride at different doping concentrations and densities of threading dislocations. At THz frequencies, all structures reveal Drude transport. The analysis of the spectral response provides the fundamental transport properties, such as the electron scattering time and the electrons' conductivity effective mass. We observe the expected impact of ionized-impurity scattering and that scattering at threading dislocations only marginally affects the high-frequency mobility.

  5. Non-nuclear electron transport channels in hollow molecules

    NASA Astrophysics Data System (ADS)

    Zhao, Jin; Petek, Hrvoje

    2014-08-01

    Electron transport in inorganic semiconductors and metals occurs through delocalized bands formed by overlapping electron orbitals. Strong correlation of electronic wave functions with the ionic cores couples the electron and lattice motions, leading to efficient interaction and scattering that degrades coherent charge transport. By contrast, unoccupied electronic states at energies near the vacuum level with diffuse molecular orbitals may form nearly-free-electron bands with density maxima in non-nuclear interstitial voids, which are subject to weaker electron-phonon interaction. The position of such bands typically above the frontier orbitals, however, renders them unstable with respect to electronic interband relaxation and therefore unsuitable for charge transport. Through electronic-structure calculations, we engineer stable, non-nuclear, nearly-free-electron conduction channels in low-dimensional molecular materials by tailoring their electrostatic and polarization potentials. We propose quantum structures of graphane-derived Janus molecular sheets with spatially isolated conducting and insulating regions that potentially exhibit emergent electronic properties, as a paradigm for molecular-scale non-nuclear charge conductors; we also describe tuning of their electronic properties by application of external fields and calculate their electron-acoustic-phonon interaction.

  6. Terahertz quantum transport in semiconductor nanostructures with the UCSB free electron lasers

    SciTech Connect

    Allen, S.J.

    1995-12-31

    Quantum transport in semiconductor nanostructures takes on new dimensions in the presence of intense terahertz electric fields. Terahertz frequencies lift us into the regime where the scattering and relaxation is not so important and strong terahertz electric fields provided by the UCSB FEL`s explore non-linear dynamics far from the perturbative limit. New quantum transport channels that are assisted by the absorption or emission of a photon appear in current voltage characteristics. We will describe some of these experiments, the new phenomena they expose and the potential impact on future terahertz semiconductor electronics.

  7. Photosynthetic, respiratory and extracellular electron transport pathways in cyanobacteria.

    PubMed

    Lea-Smith, David J; Bombelli, Paolo; Vasudevan, Ravendran; Howe, Christopher J

    2016-03-01

    Cyanobacteria have evolved elaborate electron transport pathways to carry out photosynthesis and respiration, and to dissipate excess energy in order to limit cellular damage. Our understanding of the complexity of these systems and their role in allowing cyanobacteria to cope with varying environmental conditions is rapidly improving, but many questions remain. We summarize current knowledge of cyanobacterial electron transport pathways, including the possible roles of alternative pathways in photoprotection. We describe extracellular electron transport, which is as yet poorly understood. Biological photovoltaic devices, which measure electron output from cells, and which have been proposed as possible means of renewable energy generation, may be valuable tools in understanding cyanobacterial electron transfer pathways, and enhanced understanding of electron transfer may allow improvements in the efficiency of power output. This article is part of a Special Issue entitled Organization and dynamics of bioenergetic systems in bacteria, edited by Conrad Mullineaux.

  8. Photosynthetic, respiratory and extracellular electron transport pathways in cyanobacteria.

    PubMed

    Lea-Smith, David J; Bombelli, Paolo; Vasudevan, Ravendran; Howe, Christopher J

    2016-03-01

    Cyanobacteria have evolved elaborate electron transport pathways to carry out photosynthesis and respiration, and to dissipate excess energy in order to limit cellular damage. Our understanding of the complexity of these systems and their role in allowing cyanobacteria to cope with varying environmental conditions is rapidly improving, but many questions remain. We summarize current knowledge of cyanobacterial electron transport pathways, including the possible roles of alternative pathways in photoprotection. We describe extracellular electron transport, which is as yet poorly understood. Biological photovoltaic devices, which measure electron output from cells, and which have been proposed as possible means of renewable energy generation, may be valuable tools in understanding cyanobacterial electron transfer pathways, and enhanced understanding of electron transfer may allow improvements in the efficiency of power output. This article is part of a Special Issue entitled Organization and dynamics of bioenergetic systems in bacteria, edited by Conrad Mullineaux. PMID:26498190

  9. A Guide to Electronic Multipoles in Photon Scattering and Absorption

    NASA Astrophysics Data System (ADS)

    Lovesey, Stephen William; Balcar, Ewald

    2013-02-01

    The practice of replacing matrix elements in atomic calculations by those of convenient operators with strong physical appeal has a long history, and in condensed matter physics it is perhaps best known through use of operator equivalents in electron resonance by Elliott and Stevens. Likewise, electronic multipoles, created with irreducible spherical-tensors, to represent charge-like and magnetic-like quantities are widespread in modern physics. Examples in recent headlines include a magnetic charge (a monopole), an anapole (a dipole) and a triakontadipole (a magnetic-like atomic multipole of rank 5). In this communication, we aim to guide the reader through use of atomic, spherical multipoles in photon scattering, and resonant Bragg diffraction and dichroic signals in particular. Applications to copper oxide CuO and neptunium dioxide (NpO2) are described. In keeping with it being a simple guide, there is sparse use in the communication of algebra and expressions are gathered from the published literature and not derived, even when central to the exposition. An exception is a thorough grounding, contained in an Appendix, for an appropriate version of the photon scattering length based on quantum electrodynamics. A theme of the guide is application of symmetry in scattering, in particular constraints imposed on results by symmetry in crystals. To this end, a second Appendix catalogues constraints on multipoles imposed by symmetry in crystal point-groups.

  10. Ballistic electron transport in wrinkled superlattices

    NASA Astrophysics Data System (ADS)

    Mitran, T. L.; Nemnes, G. A.; Ion, L.; Dragoman, Daniela

    2016-07-01

    Inspired by the problem of elastic wave scattering on wrinkled interfaces, we studied the scattering of ballistic electrons on a wrinkled potential energy region. The electron transmission coefficient depends on both wrinkle amplitude and periodicity, having different behaviors for positive and negative scattering potential energies. For scattering on potential barriers, minibands appear in the electron transmission, as in superlattices, whereas for scattering on periodic potential wells the transmission coefficient has a more complex form. Besides suggesting that tuning of electron transmission is possible by modifying the scattering potential via voltages on wrinkled gate electrodes, our results emphasize the analogies between ballistic electrons and elastic waves even in scattering problems on non-typical configurations.

  11. Fast electron generation and transport in a turbulent, magnetized plasma

    SciTech Connect

    Stoneking, W.R.

    1994-05-01

    The nature of fast electron generation and transport in the Madison Symmetric Torus (MST) reversed field pinch (RFP) is investigated using two electron energy analyzer (EEA) probes and a thermocouple calorimeter. The parallel velocity distribution of the fast electron population is well fit by a drifted Maxwellian distribution with temperature of about 100 eV and drift velocity of about 2 {times} 10{sup 6} m/s. Cross-calibration of the EEA with the calorimeter provides a measurement of the fast electron perpendicular temperature of 30 eV, much lower than the parallel temperature, and is evidence that the kinetic dynamo mechanism (KDT) is not operative in MST. The fast electron current is found to match to the parallel current at the edge, and the fast electron density is about 4 {times} 10{sup 11} cm{sup {minus}3} independent of the ratio of the applied toroidal electric field to the critical electric field for runaways. First time measurements of magnetic fluctuation induced particle transport are reported. By correlating electron current fluctuations with radial magnetic fluctuations the transported flux of electrons is found to be negligible outside r/a{approximately}0.9, but rises the level of the expected total particle losses inside r/a{approximately}0.85. A comparison of the measured diffusion coefficient is made with the ausilinear stochastic diffusion coefficient. Evidence exists that the reduction of the transport is due to the presence of a radial ambipolar electric field of magnitude 500 V/m, that acts to equilibrate the ion and electron transport rates. The convective energy transport associated with the measured particle transport is large enough to account for the observed magnetic fluctuation induced energy transport in MST.

  12. Non-nuclear Electron Transport Channels in Hollow Molecules

    SciTech Connect

    Zhao, Jin; Petek, Hrvoje

    2014-08-15

    Electron transport in inorganic semiconductors and metals occurs through delocalized bands formed by overlapping electron orbitals. Strong correlation of electronic wave functions with the ionic cores couples the electron and lattice motions, leading to efficient interaction and scattering that degrades coherent charge transport. By contrast, unoccupied electronic states at energies near the vacuum level with diffuse molecular orbitals may form nearly-free-electron bands with density maxima in non-nuclear interstitial voids, which are subject to weaker electron-phonon interaction. The position of such bands typically above the frontier orbitals, however, renders them unstable with respect to electronic interband relaxation and therefore unsuitable for charge transport. Through electronic-structure calculations, we engineer stable, non-nuclear, nearly-free-electron conduction channels in low-dimensional molecular materials by tailoring their electrostatic and polarization potentials. We propose quantum structures of graphane-derived Janus molecular sheets with spatially isolated conducting and insulating regions that potentially exhibit emergent electronic properties, as a paradigm for molecular-scale non-nuclear charge conductors; we also describe tuning of their electronic properties by application of external fields and calculate their electron–acoustic-phonon interaction.

  13. Spur decay of the solvated electron in picosecond radiolysis measured with time-correlated absorption spectroscopy

    SciTech Connect

    Bartels, D.M.; Cook, A.R.; Mudaliar, M.; Jonah, C.D.

    2000-03-02

    Spur decay kinetics of the hydrated electron following picosecond pulse radiolysis of water have been measured using a time-correlated transient absorption technique with an asynchronous mode-locked laser. The 11 ns time window afforded by this signal-averaging technique is ideal to match up with more conventional transient absorption measurements taken to microsecond time scales. The precise data recorded in this study require a revision downward of the time zero solvated electron yield to approximately 4.0 per 100 eV of energy absorbed, to match the best available scavenger product measurements.

  14. Electronic transport and lasing in microstructures

    SciTech Connect

    Lax, M.

    1992-01-01

    We consider the interaction of hot carriers with hot phonons in a quantum well. Transport is considered in the transverse direction and tunneling through the well barriers. Time-dependent transport effects down to the femto-second regime are included, as are strong and/or microwave fields, with negative resistance effects. Resonant tunneling assisted by phonon relaxation and infra-red radiation will be explored. The limitations on transmission of information due to partition noise, as influenced by the design of semiconductor feedback lasers will be considered. The use of light scattering and decision theory to detect shell-like aerosols is examined.

  15. Electronic absorption spectra of cryogenic systems with hydrogen bonds

    NASA Astrophysics Data System (ADS)

    Meister, T. G.; Zelikina, G. Ya.; Artamonova, O. M.

    1989-05-01

    The thermodynamic equilibrium ? has been studied by recording the 1Lb band of benzene and toluene (YR 2) dissolved in liquid Kr and CF 4 (toluene was also dissolved in liquid Ar), with addition of CHF 3(R 1XH) in a broad temperature range for each of the systems. The narrowness of the vibronic components (VC) of the 1Lb band in cryogenic solvents, i.e. liquified gases, made it possible to work with the separate vibronic components 6 10( A00) for benzene and 0-0 for toluene. The values of the equilibrium constant K were obtained by measuring the integrated intensities of the VCs of the 1Lb band of the complex and of the monomer. The enthalpy Wg  |Δ Hg| of the unexcited complex R 1XH⋯YR 2 formation was obtained from the temperature dependence of the K values; the enthalpy change Δ W due to the electronic excitation in YR 2 was obtained from the spectral shift due to the H-bond formation; therefore the enthalpy We  |Δ He| of formation of the excited complex R 1XH⋯(YE) 2* was calculated: We = Wg - Δ W. For both complexes in all the solvents used the following enthalpy values were obtained: Wg = 2.4±0.4 kcal mol -1; We = 1.6±0.5 kcal mol -1.

  16. Determination of the apparent transport constants for urate absorption in the rat proximal tubule.

    PubMed

    Sansom, S C; Senekjian, H O; Knight, T F; Babino, H; Steplock, D; Weinman, E J

    1981-05-01

    Using continuous-flow luminal microperfusion techniques, the influence of the intraluminal urate concentration on urate absorption was determined in the rat proximal tubule. When the estimated contribution of passive permeation was accounted for, the "active" component of urate absorption demonstrated saturation kinetics. The apparent Km was 0.17 mM and the Vmax 0.31 pmol.min-1.mm-1. These transport constants were similar when derived from either a water-absorbing or steady-state equilibrium perfusion solution. The reflection coefficient was determined in studies employing the techniques of simultaneous capillary and luminal microperfusion. Both perfusion solutions contained p-chloromercuribenzoate to inhibit active urate transport. In the presence or absence of an osmole gradient imposed across the tubule, the reflection coefficient for urate averaged 0.94. These studies provide evidence that urate absorption in the rat proximal tubule is a carrier-mediated process. They also provide independent confirmation of the passive flux coefficient derived in prior studies. Finally, the results suggest that solvent drag would have little effect on urate absorption.

  17. Theoretical calculations on the electron absorption spectra of selected Polycyclic Aromatic Hydrocarbons (PAH) and derivatives

    NASA Technical Reports Server (NTRS)

    Du, Ping

    1993-01-01

    As a theoretical component of the joint effort with the laboratory of Dr. Lou Allamandola to search for potential candidates for interstellar organic carbon compound that are responsible for the visible diffuse interstellar absorption bands (DIB's), quantum mechanical calculations were performed on the electron absorption spectra of selected polycyclic aromatic hydrocarbons (PAH) and derivatives. In the completed project, 15 different species of naphthalene, its hydrogen abstraction and addition derivatives, and corresponding cations and anions were studied. Using semiempirical quantum mechanical method INDO/S, the ground electronic state of each species was evaluated with restricted Hartree-Fock scheme and limited configuration interaction. The lowest energy spin state for each species was used for electron absorption calculations. Results indicate that these calculations are accurate enough to reproduce the spectra of naphthalene cation and anion observed in neon matrix. The spectral pattern of the hydrogen abstraction and addition derivatives predicted based on these results indicate that the electron configuration of the pi orbitals of these species is the dominant determinant. A combined list of 19 absorptions calculated from 4500 A to 10,400 A were compiled and suggested as potential candidates that are relevant for the DIB's absorptions. Continued studies on pyrene and derivatives revealed the ground state symmetries and multiplicities of its neutral, anionic, and cationic species. Spectral calculations show that the cation (B(sub 3g)-2) and the anion (A(sub u)-2) are more likely to have low energy absorptions in the regions between 10 kK and 20 kK, similar to naphthalene. These absorptions, together with those to be determined from the hydrogen abstraction and addition derivatives of pyrene, can be used to provide additional candidates and suggest experimental work in the search for interstellar compounds that are responsible for DIB's.

  18. Transporter-targeted cholic acid-cytarabine conjugates for improved oral absorption.

    PubMed

    Zhang, Dong; Li, Dongpo; Shang, Lei; He, Zhonggui; Sun, Jin

    2016-09-10

    Cytarabine has a poor oral absorption due to its rapid deamination and poor membrane permeability. Bile acid transporters are highly expressed both in enterocytes and hepatocytes and to increase the oral bioavailability and investigate the potential application of cytarabine for liver cancers, a transporter- recognizing prodrug strategy was applied to design and synthesize four conjugates of cytarabine with cholic acid (CA), chenodeoxycholic acid (CDCA), hyodeoxycholic acid (HDCA) and ursodeoxycholic acid (UDCA). The anticancer activities against HepG2 cells were evaluated by MTT assay and the role of bile acid transporters during cellular transport was investigated in a competitive inhibition experiment. The in vitro and in vivo metabolic stabilities of these conjugates were studied in rat plasma and liver homogenates. Finally, an oral bioavailability study was conducted in rats. All the cholic acid-cytarabine conjugates (40μM) showed potent antiproliferative activities (up to 70%) against HepG2 cells after incubation for 48h. The addition of bile acids could markedly reduce the antitumor activities of these conjugates. The N(4)-ursodeoxycholic acid conjugate of cytarabine (compound 5) exhibited optimal stability (t1/2=90min) in vitro and a 3.9-fold prolonged half-life of cytarabine in vivo. More importantly, compound 5 increased the oral bioavailability 2-fold compared with cytarabine. The results of the present study suggest that the prodrug strategy based on the bile acid transporters is suitable for improving the oral absorption and the clinical application of cytarabine. PMID:27377011

  19. RHIC electron lens beam transport system design considerations

    SciTech Connect

    Gu, X.; Pikin, A.; Okamura, M.; Fischer, W.; Luo, Y.; Gupta, R.; Hock, J.; Jain, A.; Raparia, D.

    2010-10-01

    To apply head-on beam-beam compensation for RHIC, two electron lenses are designed and will be installed at IP10. Electron beam transport system is one of important subsystem, which is used to transport electron beam from electron gun side to collector side. This system should be able to change beam size inside superconducting magnet and control beam position with 5 mm in horizontal and vertical plane. Some other design considerations for this beam transport system are also reported in this paper. The head-on beam-beam effect is one of important nonlinear source in storage ring and linear colliders, which have limited the luminosity improvement of many colliders, such as SppS, Tevatron and RHIC. In order to enhance the performance of colliders, beam-beam effects can be compensated with direct space charge compensation, indirect space charge compensation or betatron phase cancellation scheme. Like other colliders, indirect space charge compensation scheme (Electron Lens) was also proposed for Relativistic Heavy Ion Collider (RHIC) beam-beam compensation at Brookhaven National Laboratory. The two similar electron lenses are located in IR10 between the DX magnets. One RHIC electron lens consists of one DC electron gun, one superconducting magnet, one electron collector and beam transport system.

  20. Energy-filtered cold electron transport at room temperature

    PubMed Central

    Bhadrachalam, Pradeep; Subramanian, Ramkumar; Ray, Vishva; Ma, Liang-Chieh; Wang, Weichao; Kim, Jiyoung; Cho, Kyeongjae; Koh, Seong Jin

    2014-01-01

    Fermi-Dirac electron thermal excitation is an intrinsic phenomenon that limits functionality of various electron systems. Efforts to manipulate electron thermal excitation have been successful when the entire system is cooled to cryogenic temperatures, typically <1 K. Here we show that electron thermal excitation can be effectively suppressed at room temperature, and energy-suppressed electrons, whose energy distribution corresponds to an effective electron temperature of ~45 K, can be transported throughout device components without external cooling. This is accomplished using a discrete level of a quantum well, which filters out thermally excited electrons and permits only energy-suppressed electrons to participate in electron transport. The quantum well (~2 nm of Cr2O3) is formed between source (Cr) and tunnelling barrier (SiO2) in a double-barrier-tunnelling-junction structure having a quantum dot as the central island. Cold electron transport is detected from extremely narrow differential conductance peaks in electron tunnelling through CdSe quantum dots, with full widths at half maximum of only ~15 mV at room temperature. PMID:25204839

  1. Ab initio calculation of the electronic absorption spectrum of liquid water

    NASA Astrophysics Data System (ADS)

    Martiniano, Hugo F. M. C.; Galamba, Nuno; Cabral, Benedito J. Costa

    2014-04-01

    The electronic absorption spectrum of liquid water was investigated by coupling a one-body energy decomposition scheme to configurations generated by classical and Born-Oppenheimer Molecular Dynamics (BOMD). A Frenkel exciton Hamiltonian formalism was adopted and the excitation energies in the liquid phase were calculated with the equation of motion coupled cluster with single and double excitations method. Molecular dynamics configurations were generated by different approaches. Classical MD were carried out with the TIP4P-Ew and AMOEBA force fields. The BLYP and BLYP-D3 exchange-correlation functionals were used in BOMD. Theoretical and experimental results for the electronic absorption spectrum of liquid water are in good agreement. Emphasis is placed on the relationship between the structure of liquid water predicted by the different models and the electronic absorption spectrum. The theoretical gas to liquid phase blue-shift of the peak positions of the electronic absorption spectrum is in good agreement with experiment. The overall shift is determined by a competition between the O-H stretching of the water monomer in liquid water that leads to a red-shift and polarization effects that induce a blue-shift. The results illustrate the importance of coupling many-body energy decomposition schemes to molecular dynamics configurations to carry out ab initio calculations of the electronic properties in liquid phase.

  2. Ab initio calculation of the electronic absorption spectrum of liquid water

    SciTech Connect

    Martiniano, Hugo F. M. C.; Galamba, Nuno; Cabral, Benedito J. Costa

    2014-04-28

    The electronic absorption spectrum of liquid water was investigated by coupling a one-body energy decomposition scheme to configurations generated by classical and Born-Oppenheimer Molecular Dynamics (BOMD). A Frenkel exciton Hamiltonian formalism was adopted and the excitation energies in the liquid phase were calculated with the equation of motion coupled cluster with single and double excitations method. Molecular dynamics configurations were generated by different approaches. Classical MD were carried out with the TIP4P-Ew and AMOEBA force fields. The BLYP and BLYP-D3 exchange-correlation functionals were used in BOMD. Theoretical and experimental results for the electronic absorption spectrum of liquid water are in good agreement. Emphasis is placed on the relationship between the structure of liquid water predicted by the different models and the electronic absorption spectrum. The theoretical gas to liquid phase blue-shift of the peak positions of the electronic absorption spectrum is in good agreement with experiment. The overall shift is determined by a competition between the O–H stretching of the water monomer in liquid water that leads to a red-shift and polarization effects that induce a blue-shift. The results illustrate the importance of coupling many-body energy decomposition schemes to molecular dynamics configurations to carry out ab initio calculations of the electronic properties in liquid phase.

  3. Computer modeling of electron and proton transport in chloroplasts.

    PubMed

    Tikhonov, Alexander N; Vershubskii, Alexey V

    2014-07-01

    Photosynthesis is one of the most important biological processes in biosphere, which provides production of organic substances from atmospheric CO2 and water at expense of solar energy. In this review, we contemplate computer models of oxygenic photosynthesis in the context of feedback regulation of photosynthetic electron transport in chloroplasts, the energy-transducing organelles of the plant cell. We start with a brief overview of electron and proton transport processes in chloroplasts coupled to ATP synthesis and consider basic regulatory mechanisms of oxygenic photosynthesis. General approaches to computer simulation of photosynthetic processes are considered, including the random walk models of plastoquinone diffusion in thylakoid membranes and deterministic approach to modeling electron transport in chloroplasts based on the mass action law. Then we focus on a kinetic model of oxygenic photosynthesis that includes key stages of the linear electron transport, alternative pathways of electron transfer around photosystem I (PSI), transmembrane proton transport and ATP synthesis in chloroplasts. This model includes different regulatory processes: pH-dependent control of the intersystem electron transport, down-regulation of photosystem II (PSII) activity (non-photochemical quenching), the light-induced activation of the Bassham-Benson-Calvin (BBC) cycle. The model correctly describes pH-dependent feedback control of electron transport in chloroplasts and adequately reproduces a variety of experimental data on induction events observed under different experimental conditions in intact chloroplasts (variations of CO2 and O2 concentrations in atmosphere), including a complex kinetics of P700 (primary electron donor in PSI) photooxidation, CO2 consumption in the BBC cycle, and photorespiration. Finally, we describe diffusion-controlled photosynthetic processes in chloroplasts within the framework of the model that takes into account complex architecture of

  4. Study of Electron Transport and Amplification in Diamond

    SciTech Connect

    Ben-Zvi, Ilan; Muller, Erik

    2015-01-05

    The development of the Diamond Amplified Photocathode (DAP) has produced significant results under our previous HEP funded efforts both on the fabrication of working devices and the understanding of the underlying physics governing its performance. The results presented here substantiate the use of diamond as both a secondary electron amplifier for high-brightness, high-average-current electron sources and as a photon and particle detector in harsh radiation environments. Very high average current densities (>10A/cm2) have been transported through diamond material. The transport has been measured as a function of incident photon energy and found to be in good agreement with theoretical models. Measurements of the charge transport for photon energies near the carbon K-edge (290 eV for sp3 bonded carbon) have provided insight into carrier loss due to diffusion; modeling of this aspect of charge transport is underway. The response of diamond to nanosecond x-ray pulses has been measured; in this regime the charge transport is as expected. Electron emission from hydrogenated diamond has been measured using both electron and x-ray generated carriers; a gain of 178 has been observed for electron-generated carriers. The energy spectrum of the emitted electrons has been measured, providing insight into the electron affinity and ultimately the thermal emittance. The origin of charge trapping in diamond has been investigated for both bulk and surface trapping

  5. Electron transport in one-dimensional plasmas

    SciTech Connect

    Wienke, B.R.

    1983-11-01

    A one-dimensional, multigroup, discrete ordinates technique for computing electron energy deposition in plasmas is detailed. The Fokker-Planck collision operator is employed in the continuous approximation and electric fields (considered external) are included in the equation. Bremsstrahlung processes are not treated. Comparisons with analytic and Monte Carlo results are given. Fits to deposition profiles and energy scaling are proposed and discussed for monoenergetic and Maxwellian sources in the range, 0 to 150 keV, with and without uniform fields. The techniques employed to track electrons are generally useful in situations where the background plasma temperature is an order of magnitude smaller than the electron energy and collective plasma effects are negligible. We have used the approach successfully in laser pellet implosion applications.

  6. Conditioner for a helically transported electron beam

    SciTech Connect

    Wang, C.

    1992-05-01

    The kinetic theory is developed to investigate a conditioner for a helically imported electron beam. Linear expressions for axial velocity spread are derived. Numerical simulation is used to check the theoretical results and examine nonlinear aspects of the conditioning process. The results show that in the linear regime the action of the beam conditioner on a pulsed beam mainly depends on the phase at which the beam enters the conditioner and depends only slightly on the operating wavelength. In the nonlinear regime, however, the action of the conditioner strongly depends on the operating wavelength and only slightly upon the entrance phase. For a properly chosen operating wavelength, a little less than the electron`s relativistic cyclotron wavelength, the conditioner can decrease the axial velocity spread of a pulsed beam down to less than one-third of its initial value.

  7. Coherent electron transport in a helical nanotube

    NASA Astrophysics Data System (ADS)

    Liang, Guo-Hua; Wang, Yong-Long; Du, Long; Jiang, Hua; Kang, Guang-Zhen; Zong, Hong-Shi

    2016-09-01

    The quantum dynamics of carriers bound to helical tube surfaces is investigated in a thin-layer quantization scheme. By numerically solving the open-boundary Schrödinger equation in curvilinear coordinates, geometric effect on the coherent transmission spectra is analysed in the case of single propagating mode as well as multimode. It is shown that, the coiling endows the helical nanotube with different transport properties from a bent cylindrical surface. Fano resonance appears as a purely geometric effect in the conductance, the corresponding energy of quasibound state is obviously influenced by the torsion and length of the nanotube. We also find new plateaus in the conductance. The transport of double-degenerate mode in this geometry is reminiscent of the Zeeman coupling between the magnetic field and spin angular momentum in quasi-one-dimensional structure.

  8. A Deterministic Transport Code for Space Environment Electrons

    NASA Technical Reports Server (NTRS)

    Nealy, John E.; Chang, C. K.; Norman, Ryan B.; Blattnig, Steve R.; Badavi, Francis F.; Adamczyk, Anne M.

    2010-01-01

    A deterministic computational procedure has been developed to describe transport of space environment electrons in various shield media. This code is an upgrade and extension of an earlier electron code. Whereas the former code was formulated on the basis of parametric functions derived from limited laboratory data, the present code utilizes well established theoretical representations to describe the relevant interactions and transport processes. The shield material specification has been made more general, as have the pertinent cross sections. A combined mean free path and average trajectory approach has been used in the transport formalism. Comparisons with Monte Carlo calculations are presented.

  9. Neoclassical electron transport in tokamaks with neutral-beam injection

    SciTech Connect

    Helander, P.; Akers, R.J.

    2005-04-15

    The collisional interaction between neutral-beam ions and bulk plasma electrons leads to convective transport of particles and energy similar to the well-known Ware pinch. These transport fluxes are calculated, and it is found that the particle flux is outward when the neutral beams are in the same direction as the plasma current and inward otherwise, while the opposite holds for the electron heat transport. This effectively shifts the neutral-beam fueling profile approximately one fast-ion banana width outward during coinjection and inward during counterinjection, and could help to explain why very different plasma behavior is sometimes observed when the direction of the plasma current is reversed.

  10. X-ray absorption study of the electronic structure of Mn-doped amorphous Si

    SciTech Connect

    Arenholz, Elke; Zeng, Li; Huegel, A.; Helgren, E.; Hellman, F.; Piamonteze, C.; Arenholz, E.

    2008-03-08

    The electronic structure of Mn in amorphous Si (a-Mn{sub x}Si{sub 1?x}) is studied by X-ray absorption spectroscopy at the Mn L{sub 3,2} edges for x = 0.005-0.18. Except the x = 0.005 sample, which shows a slight signature of Mn{sup 2+} atomic multiplets associated with a local Mn moment, all samples have broad and featureless L{sub 3,2} absorption peaks, corresponding to an itinerant state for all 3d electrons. The broad X-ray absorption spectra exclude the possibility of a localized 3d moment and explain the unexpectedly quenched Mn moment in this magnetically-doped amorphous semiconductor. Such a fully delocalized d state of Mn dopant in Si has not been previously suggested.

  11. Plane-wave DFT-LDA calculation of the electronic structure and absorption spectrum of copper

    NASA Astrophysics Data System (ADS)

    Marini, Andrea; Onida, Giovanni; del Sole, Rodolfo

    2001-11-01

    We present an accurate, first-principles study of the electronic structure and absorption spectrum of bulk copper within density functional theory in the local density approximation, including the study of intraband transitions. We construct norm-conserving pseudopotentials (PP's) including the 3d shell (and optionally the underlying 3s and 3p shells) in the valence and requiring a relatively small plane-wave basis (60 and 140 Ry cutoff, respectively). As a consequence, these PP's are strongly nonlocal, yielding macroscopically wrong results in the absorption spectrum when momentum matrix elements are computed naively. Our results are compared with experimental photoemission, absorption, and electron energy loss data, and suggest nontrivial self-energy effects in the quasiparticle spectrum of Cu.

  12. Transport of secondary electrons and reactive species in ion tracks

    NASA Astrophysics Data System (ADS)

    Surdutovich, Eugene; Solov'yov, Andrey V.

    2015-08-01

    The transport of reactive species brought about by ions traversing tissue-like medium is analysed analytically. Secondary electrons ejected by ions are capable of ionizing other molecules; the transport of these generations of electrons is studied using the random walk approximation until these electrons remain ballistic. Then, the distribution of solvated electrons produced as a result of interaction of low-energy electrons with water molecules is obtained. The radial distribution of energy loss by ions and secondary electrons to the medium yields the initial radial dose distribution, which can be used as initial conditions for the predicted shock waves. The formation, diffusion, and chemical evolution of hydroxyl radicals in liquid water are studied as well. COST Action Nano-IBCT: Nano-scale Processes Behind Ion-Beam Cancer Therapy.

  13. Catalytic photoinduced electron transport across a lipid bilayer mediated by a membrane-soluble electron relay.

    PubMed

    Limburg, B; Bouwman, E; Bonnet, S

    2015-12-14

    Unidirectional photocatalytic electron transfer from a hydrophilic electron donor encapsulated in the interior of a liposome, to a hydrophilic electron acceptor on the other side of the membrane, has been achieved using the simple membrane-soluble electron relay 1-methoxy-N-methylphenazinium (MMP(+)). The total amount of photoproduct (>140 nmol) exceeds the number of moles of MMP(+) present (125 nmol), thus showing that the transport of electrons is catalytic.

  14. Electron Trapping and Charge Transport by Large Amplitude Whistlers

    NASA Technical Reports Server (NTRS)

    Kellogg, P. J.; Cattell, C. A.; Goetz, K.; Monson, S. J.; Wilson, L. B., III

    2010-01-01

    Trapping of electrons by magnetospheric whistlers is investigated using data from the Waves experiment on Wind and the S/WAVES experiment on STEREO. Waveforms often show a characteristic distortion which is shown to be due to electrons trapped in the potential of the electrostatic part of oblique whistlers. The density of trapped electrons is significant, comparable to that of the unperturbed whistler. Transport of these trapped electrons to new regions can generate potentials of several kilovolts, Trapping and the associated potentials may play an important role in the acceleration of Earth's radiation belt electrons.

  15. A Deterministic Computational Procedure for Space Environment Electron Transport

    NASA Technical Reports Server (NTRS)

    Nealy, John E.; Chang, C. K.; Norman, Ryan B.; Blattnig, Steve R.; Badavi, Francis F.; Adamcyk, Anne M.

    2010-01-01

    A deterministic computational procedure for describing the transport of electrons in condensed media is formulated to simulate the effects and exposures from spectral distributions typical of electrons trapped in planetary magnetic fields. The primary purpose for developing the procedure is to provide a means of rapidly performing numerous repetitive transport calculations essential for electron radiation exposure assessments for complex space structures. The present code utilizes well-established theoretical representations to describe the relevant interactions and transport processes. A combined mean free path and average trajectory approach is used in the transport formalism. For typical space environment spectra, several favorable comparisons with Monte Carlo calculations are made which have indicated that accuracy is not compromised at the expense of the computational speed.

  16. Light absorption and electrical transport in Si:O alloys for photovoltaics

    SciTech Connect

    Mirabella, S.; Crupi, I.; Miritello, M.; Simone, F.; Di Martino, G.; Di Stefano, M. A.; Di Marco, S.; Priolo, F.

    2010-11-15

    Thin films (100-500 nm) of the Si:O alloy have been systematically characterized in the optical absorption and electrical transport behavior, by varying the Si content from 43 up to 100 at. %. Magnetron sputtering or plasma enhanced chemical vapor deposition have been used for the Si:O alloy deposition, followed by annealing up to 1250 deg. C. Boron implantation (30 keV, 3-30x10{sup 14} B/cm{sup 2}) on selected samples was performed to vary the electrical sheet resistance measured by the four-point collinear probe method. Transmittance and reflectance spectra have been extracted and combined to estimate the absorption spectra and the optical band gap, by means of the Tauc analysis. Raman spectroscopy was also employed to follow the amorphous-crystalline (a-c) transition of the Si domains contained in the Si:O films. The optical absorption and the electrical transport of Si:O films can be continuously and independently modulated by acting on different parameters. The light absorption increases (by one decade) with the Si content in the 43-100 at. % range, determining an optical band gap which can be continuously modulated into the 2.6-1.6 eV range, respectively. The a-c phase transition in Si:O films, causing a significant reduction in the absorption coefficient, occurs at increasing temperatures (from 600 to 1100 deg. C) as the Si content decreases. The electrical resistivity of Si:O films can be varied among five decades, being essentially dominated by the number of Si grains and by the doping. Si:O alloys with Si content in the 60-90 at. % range (named oxygen rich silicon films), are proved to join an appealing optical gap with a viable conductivity, being a good candidate for increasing the conversion efficiency of thin-film photovoltaic cell.

  17. Electron transport through nuclear pasta in magnetized neutron stars

    NASA Astrophysics Data System (ADS)

    Yakovlev, D. G.

    2015-10-01

    We present a simple model for electron transport in a possible layer of exotic nuclear clusters (in the so-called nuclear pasta layer) between the crust and liquid core of a strongly magnetized neutron star. The electron transport there can be strongly anisotropic and gyrotropic. The anisotropy is produced by different electron effective collision frequencies along and across local symmetry axis in domains of exotic ordered nuclear clusters and by complicated effects of the magnetic field. We also calculate averaged kinetic coefficients in case local domains are freely oriented. Possible applications of the obtained results and open problems are outlined.

  18. Multidimensional electron-photon transport with standard discrete ordinates codes

    SciTech Connect

    Drumm, C.R.

    1995-12-31

    A method is described for generating electron cross sections that are compatible with standard discrete ordinates codes without modification. There are many advantages of using an established discrete ordinates solver, e.g. immediately available adjoint capability. Coupled electron-photon transport capability is needed for many applications, including the modeling of the response of electronics components to space and man-made radiation environments. The cross sections have been successfully used in the DORT, TWODANT and TORT discrete ordinates codes. The cross sections are shown to provide accurate and efficient solutions to certain multidimensional electronphoton transport problems.

  19. Treating electron transport in MCNP{sup trademark}

    SciTech Connect

    Hughes, H.G.

    1996-12-31

    The transport of electrons and other charged particles is fundamentally different from that of neutrons and photons. A neutron, in aluminum slowing down from 0.5 MeV to 0.0625 MeV will have about 30 collisions; a photon will have fewer than ten. An electron with the same energy loss will undergo 10{sup 5} individual interactions. This great increase in computational complexity makes a single- collision Monte Carlo approach to electron transport unfeasible for many situations of practical interest. Considerable theoretical work has been done to develop a variety of analytic and semi-analytic multiple-scattering theories for the transport of charged particles. The theories used in the algorithms in MCNP are the Goudsmit-Saunderson theory for angular deflections, the Landau an theory of energy-loss fluctuations, and the Blunck-Leisegang enhancements of the Landau theory. In order to follow an electron through a significant energy loss, it is necessary to break the electron`s path into many steps. These steps are chosen to be long enough to encompass many collisions (so that multiple-scattering theories are valid) but short enough that the mean energy loss in any one step is small (for the approximations in the multiple-scattering theories). The energy loss and angular deflection of the electron during each step can then be sampled from probability distributions based on the appropriate multiple- scattering theories. This subsumption of the effects of many individual collisions into single steps that are sampled probabilistically constitutes the ``condensed history`` Monte Carlo method. This method is exemplified in the ETRAN series of electron/photon transport codes. The ETRAN codes are also the basis for the Integrated TIGER Series, a system of general-purpose, application-oriented electron/photon transport codes. The electron physics in MCNP is similar to that of the Integrated TIGER Series.

  20. Theoretical study of particle transport in electron internal transport barriers in TCV

    SciTech Connect

    Fable, E.; Sauter, O.; Marinoni, A.; Zucca, C.

    2006-11-30

    Previous results from the analysis of fully non inductively sustained electron internal transport barriers (eITBs) in TCV show that a strong coupling exists between electron temperature and density profiles inside the barrier. A phenomenology that is completely different from the standard L-mode is observed . New experimental results assess transient phases to calculate particle convection and diffusion coefficients, allowing also to discuss the role of neoclassical transport. Gyrokinetic and gyrofluid analysis of steady-state eITBs provide tools to understand the mechanism that drive the observed density peaking in advanced scenarios with internal transport barriers and dominant electron heating.

  1. Electronic transport in ultranarrow zigzag graphene nanoribbons with edge disorders

    NASA Astrophysics Data System (ADS)

    Liu, Y. L.; Xu, G. L.; Zhang, X. W.

    2016-11-01

    We investigate the transport properties of ultranarrow zigzag graphene nanoribbons (ZGNRs) with edge vacancies by using recursive Green's function method. Transport gaps are observed when the vacancies are distributed uniformly on both sides. In addition, ZGNRs with symmetrical structure have much larger transport gaps than the asymmetrical ones. This phenomenon results from the different band structures between them. We also calculate the conductance of ZGNRs with edge vacancies distributed randomly. It shows that transport gaps decrease exponentially with the increasing of ZGNRs width because the symmetry of structure is broken by the random edge vacancies. Localization analysis reveals that the electronic transport channels around Fermi energy are blockaded so that they are not responsible for electron transmission.

  2. Study of electron transport in hydrocarbon gases

    NASA Astrophysics Data System (ADS)

    Hasegawa, H.; Date, H.

    2015-04-01

    The drift velocity and the effective ionization coefficient of electrons in the organic gases, C2H2, C2H4, C2H6, CH3OH, C2H5OH, C6H6, and C6H5CH3, have been measured over relatively wide ranges of density-reduced electric fields (E/N) at room temperature (around 300 K). The drift velocity was measured, based on the arrival-time spectra of electrons by using a double-shutter drift tube over the E/N range from 300 to 2800 Td, and the effective ionization coefficient (α - η) was determined by the steady-state Townsend method from 150 to 3000 Td. Whenever possible, these parameters were compared with those available in the literature. It has been shown that the swarm parameters for these gases have specific tendencies, depending on their molecular configurations.

  3. Conditioner for a helically transported electron beam

    SciTech Connect

    Wang, C.

    1992-05-01

    The kinetic theory is developed to investigate a conditioner for a helically imported electron beam. Linear expressions for axial velocity spread are derived. Numerical simulation is used to check the theoretical results and examine nonlinear aspects of the conditioning process. The results show that in the linear regime the action of the beam conditioner on a pulsed beam mainly depends on the phase at which the beam enters the conditioner and depends only slightly on the operating wavelength. In the nonlinear regime, however, the action of the conditioner strongly depends on the operating wavelength and only slightly upon the entrance phase. For a properly chosen operating wavelength, a little less than the electron's relativistic cyclotron wavelength, the conditioner can decrease the axial velocity spread of a pulsed beam down to less than one-third of its initial value.

  4. Surface excitations in the modelling of electron transport for electron-beam-induced deposition experiments

    PubMed Central

    Valentí, Roser; Werner, Wolfgang S

    2015-01-01

    Summary The aim of the present overview article is to raise awareness of an essential aspect that is usually not accounted for in the modelling of electron transport for focused-electron-beam-induced deposition (FEBID) of nanostructures: Surface excitations are on the one hand responsible for a sizeable fraction of the intensity in reflection-electron-energy-loss spectra for primary electron energies of up to a few kiloelectronvolts and, on the other hand, they play a key role in the emission of secondary electrons from solids, regardless of the primary energy. In this overview work we present a general perspective of recent works on the subject of surface excitations and on low-energy electron transport, highlighting the most relevant aspects for the modelling of electron transport in FEBID simulations. PMID:26171301

  5. The absorption of trapped particles by the inner satellites of Jupiter and the radial diffusion coefficient of particle transport

    NASA Technical Reports Server (NTRS)

    Mogro-Campero, A.; Fillius, W.

    1976-01-01

    The process of trapped particle absorption by the inner Jovian satellites is considered in detail taking into account both the particle and satellite motions in a magnetic dipole field which is displaced from the center of the planet and tilted with respect to the planetary rotation axis. An expression is derived for computing the sweeping time at a given satellite, defined as the time required for the satellite to sweep up a given fraction of the trapped particles within its sweeping region. By making use of the sweeping time and the radial diffusion equation of particle transport approximate expressions for the diffusion coefficient are derived. Measurements obtained by Pioneer 10 are then used to obtain estimates of the diffusion coefficient at the orbits of Io and Europa. We find that the diffusion coefficient is a function of energy and magnetic latitude for electrons in the energy range 0.7-14 MeV.

  6. X-ray absorption spectroscopy elucidates the impact of structural disorder on electron mobility in amorphous zinc-tin-oxide thin films

    SciTech Connect

    Siah, Sin Cheng E-mail: buonassisi@mit.edu; Lee, Yun Seog; Buonassisi, Tonio E-mail: buonassisi@mit.edu; Lee, Sang Woon; Gordon, Roy G.; Heo, Jaeyeong; Shibata, Tomohiro; Segre, Carlo U.

    2014-06-16

    We investigate the correlation between the atomic structures of amorphous zinc-tin-oxide (a-ZTO) thin films grown by atomic layer deposition (ALD) and their electronic transport properties. We perform synchrotron-based X-ray absorption spectroscopy at the K-edges of Zn and Sn with varying [Zn]/[Sn] compositions in a-ZTO thin films. In extended X-ray absorption fine structure (EXAFS) measurements, signal attenuation from higher-order shells confirms the amorphous structure of a-ZTO thin films. Both quantitative EXAFS modeling and X-ray absorption near edge spectroscopy (XANES) reveal that structural disorder around Zn atoms increases with increasing [Sn]. Field- and Hall-effect mobilities are observed to decrease with increasing structural disorder around Zn atoms, suggesting that the degradation in electron mobility may be correlated with structural changes.

  7. Study of electron transport in hydrocarbon gases

    SciTech Connect

    Hasegawa, H.; Date, H.

    2015-04-07

    The drift velocity and the effective ionization coefficient of electrons in the organic gases, C{sub 2}H{sub 2}, C{sub 2}H{sub 4}, C{sub 2}H{sub 6}, CH{sub 3}OH, C{sub 2}H{sub 5}OH, C{sub 6}H{sub 6}, and C{sub 6}H{sub 5}CH{sub 3}, have been measured over relatively wide ranges of density-reduced electric fields (E/N) at room temperature (around 300 K). The drift velocity was measured, based on the arrival-time spectra of electrons by using a double-shutter drift tube over the E/N range from 300 to 2800 Td, and the effective ionization coefficient (α − η) was determined by the steady-state Townsend method from 150 to 3000 Td. Whenever possible, these parameters were compared with those available in the literature. It has been shown that the swarm parameters for these gases have specific tendencies, depending on their molecular configurations.

  8. Evidence for global electron transportation into the jovian inner magnetosphere.

    PubMed

    Yoshioka, K; Murakami, G; Yamazaki, A; Tsuchiya, F; Kimura, T; Kagitani, M; Sakanoi, T; Uemizu, K; Kasaba, Y; Yoshikawa, I; Fujimoto, M

    2014-09-26

    Jupiter's magnetosphere is a strong particle accelerator that contains ultrarelativistic electrons in its inner part. They are thought to be accelerated by whistler-mode waves excited by anisotropic hot electrons (>10 kiloelectron volts) injected from the outer magnetosphere. However, electron transportation in the inner magnetosphere is not well understood. By analyzing the extreme ultraviolet line emission from the inner magnetosphere, we show evidence for global inward transport of flux tubes containing hot plasma. High-spectral-resolution scanning observations of the Io plasma torus in the inner magnetosphere enable us to generate radial profiles of the hot electron fraction. It gradually decreases with decreasing radial distance, despite the short collisional time scale that should thermalize them rapidly. This indicates a fast and continuous resupply of hot electrons responsible for exciting the whistler-mode waves.

  9. Evidence for global electron transportation into the jovian inner magnetosphere.

    PubMed

    Yoshioka, K; Murakami, G; Yamazaki, A; Tsuchiya, F; Kimura, T; Kagitani, M; Sakanoi, T; Uemizu, K; Kasaba, Y; Yoshikawa, I; Fujimoto, M

    2014-09-26

    Jupiter's magnetosphere is a strong particle accelerator that contains ultrarelativistic electrons in its inner part. They are thought to be accelerated by whistler-mode waves excited by anisotropic hot electrons (>10 kiloelectron volts) injected from the outer magnetosphere. However, electron transportation in the inner magnetosphere is not well understood. By analyzing the extreme ultraviolet line emission from the inner magnetosphere, we show evidence for global inward transport of flux tubes containing hot plasma. High-spectral-resolution scanning observations of the Io plasma torus in the inner magnetosphere enable us to generate radial profiles of the hot electron fraction. It gradually decreases with decreasing radial distance, despite the short collisional time scale that should thermalize them rapidly. This indicates a fast and continuous resupply of hot electrons responsible for exciting the whistler-mode waves. PMID:25258073

  10. Evidence for global electron transportation into the jovian inner magnetosphere

    NASA Astrophysics Data System (ADS)

    Yoshioka, K.; Murakami, G.; Yamazaki, A.; Tsuchiya, F.; Kimura, T.; Kagitani, M.; Sakanoi, T.; Uemizu, K.; Kasaba, Y.; Yoshikawa, I.; Fujimoto, M.

    2014-09-01

    Jupiter’s magnetosphere is a strong particle accelerator that contains ultrarelativistic electrons in its inner part. They are thought to be accelerated by whistler-mode waves excited by anisotropic hot electrons (>10 kiloelectron volts) injected from the outer magnetosphere. However, electron transportation in the inner magnetosphere is not well understood. By analyzing the extreme ultraviolet line emission from the inner magnetosphere, we show evidence for global inward transport of flux tubes containing hot plasma. High-spectral-resolution scanning observations of the Io plasma torus in the inner magnetosphere enable us to generate radial profiles of the hot electron fraction. It gradually decreases with decreasing radial distance, despite the short collisional time scale that should thermalize them rapidly. This indicates a fast and continuous resupply of hot electrons responsible for exciting the whistler-mode waves.

  11. Potential benefits of triethylamine as n-electron donor in the estimation of forskolin by electronic absorption and emission spectroscopy

    NASA Astrophysics Data System (ADS)

    Raju, Gajula; Ram Reddy, A.

    2016-02-01

    Diterpenoid forskolin was isolated from Coleus forskolii. The electronic absorption and emission studies of forskolin were investigated in various solvents with an aim to improve its detection limits. The two chromophores present in the diterpenoid are not conjugated leading to the poor absorption and emission of UV light. The absorption and fluorescence spectra were solvent specific. In the presence of a monodentate ligand, triethylamine the detection of forskolin is improved by 3.63 times in ethanol with the fluorescence method and 3.36 times in DMSO by the absorption spectral method. The longer wavelength absorption maximum is blue shifted while the lower energy fluorescence maximum is red shifted in the presence of triethylamine. From the wavelength of fluorescence maxima of the exciplex formed between excited forskolin and triethylamine it is concluded that the order of reactivity of hydroxyl groups in the excited state forskolin is in the reverse order to that of the order of the reactivity of hydroxyl groups in its ground state.

  12. Absorptive potentials due to ionization and thermal diffuse scattering by fast electrons in crystals

    SciTech Connect

    Allen, L.J. ); Rossouw, C.J. )

    1990-12-15

    An expression for the Fourier coefficients of the absorptive potential due to electron-impact ionization in crystals is derived and the cross section is given in terms of these Fourier components. Absorptive potentials due to {ital K}-shell ionization and thermal diffuse scattering (TDS) are calculated with use of a hydrogenic model and an Einstein model, respectively. Inelastic potentials require integration over all states of the scattered electron and, for {ital K}-shell ionization, integration over all states of the ejected electron. These potentials are thus dependent on incident-beam energy, in contrast with the elastic potential. The projected spatial distribution of these potentials are plotted and compared with the elastic potential for CdTe, GaAs, Si, and diamond. The delocalization of the ionization absorptive potential is similar to that expected from classical impact-parameter arguments. The form of the TDS potential is substantially different from that due to elastic scattering, being extremely peaked on atomic positions with no absorption in the channels between atomic planes.

  13. Electron mobility and free-carrier absorption in GaAs - Determination of the compensation ratio

    NASA Technical Reports Server (NTRS)

    Walukiewicz, W.; Lagowski, L.; Jastrzebski, L.; Lichtensteiger, M.; Gatos, H. C.

    1979-01-01

    Theoretical calculations of electron mobility and free-carrier absorption in n-type GaAs at room temperature were carried out taking into consideration all major scattering processes. It was found that satisfactory agreement between theoretical and experimental results on free-carrier absorption is obtained only when the effect of compensation is quantitatively taken into account. In conjunction with experimental studies it is shown that the electron mobility (for n greater than 10 to the 15th per cu cm) and free-carrier absorption (for n greater than 10 to the 16th per cu cm) are sufficiently sensitive to the ionized impurity concentration to provide a reliable means for determining the compensation ratio. Convenient procedures are presented for the determination of the compensation ratio from the free-carrier absorption coefficient and from the computed values of room-temperature electron mobility. Values of the compensation ratio obtained by these two procedures are in good agreement provided the carrier-concentration variations in the material are not appreciably greater than 10%.

  14. Electron paramagnetic resonance and low-field microwave absorption in the manganese-gallium oxide

    NASA Astrophysics Data System (ADS)

    Montiel, H.; Alvarez, G.; Conde-Gallardo, A.; Zamorano, R.

    2015-07-01

    Microwave absorption measurements in MnGa2O4 powders are carried out at X-band (8.8-9.8 GHz) in 92-296 K temperature range. For all temperatures, the electron paramagnetic resonance (EPR) spectra show a single broad line due to Mn2+ ions. Temperature dependence of the EPR parameters: the peak-to-peak linewidth (ΔHpp), the integrated intensity (IEPR) and the g-factor, suggests the presence of magnetic fluctuations that precede to antiferromagnetic ordering at low temperature. Additionally, the low-field microwave absorption (LFMA) is used to give further information on this material, giving also evidence of these magnetic fluctuations.

  15. Non-uniform absorption of terahertz radiation on superconducting hot electron bolometer microbridges

    SciTech Connect

    Miao, W.; Zhang, W.; Zhong, J. Q.; Shi, S. C.; Delorme, Y.; Lefevre, R.; Feret, A.; Vacelet, T.

    2014-02-03

    We interpret the experimental observation of a frequency-dependence of superconducting hot electron bolometer (HEB) mixers by taking into account the non-uniform absorption of the terahertz radiation on the superconducting HEB microbridge. The radiation absorption is assumed to be proportional to the local surface resistance of the HEB microbridge, which is computed using the Mattis-Bardeen theory. With this assumption the dc and mixing characteristics of a superconducting niobium-nitride (NbN) HEB device have been modeled at frequencies below and above the equilibrium gap frequency of the NbN film.

  16. Application of the mathematical Graf's addition theorem to the problem of electron energy absorption in laser-irradiated plasma

    NASA Astrophysics Data System (ADS)

    Krainov, V. P.

    2013-03-01

    The electron energy absorption in laser-irradiated plasma is determined by the sum of the rates of photon absorption and emission. These rates contain the square of the Bessel functions. It was shown that in a moderate laser field, terms with absorption and emission of several photons are large, but cancel exactly each other. Therefore, we should take into account terms with the absorption and emission of only one laser photon. This statement is proved analytically using Graf's theorem for Bessel functions.

  17. Dissipationless electron transport in photon-dressed nanostructures.

    PubMed

    Kibis, O V

    2011-09-01

    It is shown that the electron coupling to photons in field-dressed nanostructures can result in the ground electron-photon state with a nonzero electric current. Since the current is associated with the ground state, it flows without the Joule heating of the nanostructure and is nondissipative. Such a dissipationless electron transport can be realized in strongly coupled electron-photon systems with the broken time-reversal symmetry--particularly, in quantum rings and chiral nanostructures dressed by circularly polarized photons. PMID:21981519

  18. Effect of dephasing on DNA sequencing via transverse electronic transport

    SciTech Connect

    Zwolak, Michael; Krems, Matt; Pershin, Yuriy V; Di Ventra, Massimiliano

    2009-01-01

    We study theoretically the effects of dephasing on DNA sequencing in a nanopore via transverse electronic transport. To do this, we couple classical molecular dynamics simulations with transport calculations using scattering theory. Previous studies, which did not include dephasing, have shown that by measuring the transverse current of a particular base multiple times, one can get distributions of currents for each base that are distinguishable. We introduce a dephasing parameter into transport calculations to simulate the effects of the ions and other fluctuations. These effects lower the overall magnitude of the current, but have little effect on the current distributions themselves. The results of this work further implicate that distinguishing DNA bases via transverse electronic transport has potential as a sequencing tool.

  19. Status of electron transport in MCNP{trademark}

    SciTech Connect

    Hughes, H.G.

    1997-10-01

    The latest version of MCNP, the Los Alamos Monte Carlo transport code, has now been officially released. A variety of new features are available in MCNP4B. Among these are differential operator perturbations, cross section plotting capabilities, enhanced diagnostics for transport in repeated structures and lattices, improved efficiency in distributed memory multiprocessing, corrected particle lifetime and lifespan estimators, and expanded software quality assurance procedures and testing, including testing of the multigroup Boltzmann Fokker Planck capability. New and improved cross section sets in the form of ENDF/B-VI evaluations have also been recently released and can be used in MCNP4B. Perhaps most significant for the interests of this special session, the electron transport algorithm has been improved, especially in the collisional energy loss straggling and the angular deflection treatments. In this paper, I shall concentrate on a fairly complete documentation of the current status of the electron transport methods in MCNP.

  20. Electron-Transport Properties of Few-Layer Black Phosphorus.

    PubMed

    Xu, Yuehua; Dai, Jun; Zeng, Xiao Cheng

    2015-06-01

    We perform the first-principles computational study of the effect of number of stacking layers and stacking style of the few-layer black phosphorus (BPs) on the electronic properties, including transport gap, current-voltage (i-v) relation, and differential conductance. Our computation is based on the nonequilibrium Green's function approach combined with density functional theory calculations. Specifically, we compute electron-transport properties of monolayer BP, bilayer BP, and trilayer BP as well as bilayer BPs with AB-, AA-, or AC-stacking. We find that the stacking number has greater influence on the transport gap than the stacking type. Conversely, the stacking type has greater influence on i-v curve and differential conductance than on the transport gap. This study offers useful guidance for determining the number of stacking layers and the stacking style of few-layer BP sheets in future experimental measurements and for potential applications in nanoelectronic devices.

  1. Mitochondrial ROS Produced via Reverse Electron Transport Extend Animal Lifespan

    PubMed Central

    Scialò, Filippo; Sriram, Ashwin; Fernández-Ayala, Daniel; Gubina, Nina; Lõhmus, Madis; Nelson, Glyn; Logan, Angela; Cooper, Helen M.; Navas, Plácido; Enríquez, Jose Antonio; Murphy, Michael P.; Sanz, Alberto

    2016-01-01

    Summary Increased production of reactive oxygen species (ROS) has long been considered a cause of aging. However, recent studies have implicated ROS as essential secondary messengers. Here we show that the site of ROS production significantly contributes to their apparent dual nature. We report that ROS increase with age as mitochondrial function deteriorates. However, we also demonstrate that increasing ROS production specifically through respiratory complex I reverse electron transport extends Drosophila lifespan. Reverse electron transport rescued pathogenesis induced by severe oxidative stress, highlighting the importance of the site of ROS production in signaling. Furthermore, preventing ubiquinone reduction, through knockdown of PINK1, shortens lifespan and accelerates aging; phenotypes that are rescued by increasing reverse electron transport. These results illustrate that the source of a ROS signal is vital in determining its effects on cellular physiology and establish that manipulation of ubiquinone redox state is a valid strategy to delay aging. PMID:27076081

  2. Mitochondrial ROS Produced via Reverse Electron Transport Extend Animal Lifespan.

    PubMed

    Scialò, Filippo; Sriram, Ashwin; Fernández-Ayala, Daniel; Gubina, Nina; Lõhmus, Madis; Nelson, Glyn; Logan, Angela; Cooper, Helen M; Navas, Plácido; Enríquez, Jose Antonio; Murphy, Michael P; Sanz, Alberto

    2016-04-12

    Increased production of reactive oxygen species (ROS) has long been considered a cause of aging. However, recent studies have implicated ROS as essential secondary messengers. Here we show that the site of ROS production significantly contributes to their apparent dual nature. We report that ROS increase with age as mitochondrial function deteriorates. However, we also demonstrate that increasing ROS production specifically through respiratory complex I reverse electron transport extends Drosophila lifespan. Reverse electron transport rescued pathogenesis induced by severe oxidative stress, highlighting the importance of the site of ROS production in signaling. Furthermore, preventing ubiquinone reduction, through knockdown of PINK1, shortens lifespan and accelerates aging; phenotypes that are rescued by increasing reverse electron transport. These results illustrate that the source of a ROS signal is vital in determining its effects on cellular physiology and establish that manipulation of ubiquinone redox state is a valid strategy to delay aging.

  3. Experimental observation of microwave absorption and electron heating due to the two plasmon decay instability and resonance absorption

    SciTech Connect

    Rasmussen, D.A.

    1981-01-01

    The interaction of intense microwaves with an inhomogeneous plasma is studied in two experimental devices. In the first device an investigation was made of microwave absorption and electron heating due to the parametric decay of microwaves into electron plasma waves (Two Plasmon Decay instability, TPDI), modeling a process which can occur near the quarter critical surface in laser driven pellets. P-polarized microwave (f = 1.2 GHz, P/sub 0/ less than or equal to 12 kW) are applied to an essentially collisionless, inhomogeneous plasma, in an oversized waveguide, in the U.C. Davis Prometheus III device. The initial density scale length near the quarter critical surface is quite long (L/lambda/sub De/ approx. = 3000 or k/sub 0/L approx. = 15). The observed threshold power for the TPDI is quite low (P/sub T/approx. = 0.1 kW or v/sub os//v/sub e/ approx. = 0.1). Near the threshold the decay waves only occur near the quarter critical surface. As the incident power is increased above threshold, the decay waves spread to lower densities, and for P/sub 0/ greater than or equal to lkW, (v/sub os//v/sub e/ greater than or equal to 0.3) suprathermal electron heating is strong for high powers (T/sub H/ less than or equal to 12 T/sub e/ for P/sub 0/ less than or equal to 8 kW or v/sub os//v/sub e/ less than or equal to 0.9).

  4. Progress in Simulating Turbulent Electron Thermal Transport in NSTX

    SciTech Connect

    Guttenfelder, Walter; Kaye, S. M.; Ren, Y.; Bell, R. E.; Hammett, G. W.; LeBlanc, B. P.; Mikkelsen, D. R.; Peterson, J. L.; Nevins, W. M.; Candy, J.; Yuh, H.

    2013-07-17

    Nonlinear simulations based on multiple NSTX discharge scenarios have progressed to help differentiate unique instability mechanisms and to validate with experimental turbulence and transport data. First nonlinear gyrokinetic simulations of microtearing (MT) turbulence in a high-beta NSTX H-mode discharge predict experimental levels of electron thermal transport that are dominated by magnetic flutter and increase with collisionality, roughly consistent with energy confinement times in dimensionless collisionality scaling experiments. Electron temperature gradient (ETG) simulations predict significant electron thermal transport in some low and high beta discharges when ion scales are suppressed by E x B shear. Although the predicted transport in H-modes is insensitive to variation in collisionality (inconsistent with confinement scaling), it is sensitive to variations in other parameters, particularly density gradient stabilization. In reversed shear (RS) Lmode discharges that exhibit electron internal transport barriers, ETG transport has also been shown to be suppressed nonlinearly by strong negative magnetic shear, s<<0. In many high beta plasmas, instabilities which exhibit a stiff beta dependence characteristic of kinetic ballooning modes (KBM) are sometimes found in the core region. However, they do not have a distinct finite beta threshold, instead transitioning gradually to a trapped electron mode (TEM) as beta is reduced to zero. Nonlinear simulations of this "hybrid" TEM/KBM predict significant transport in all channels, with substantial contributions from compressional magnetic perturbations. As multiple instabilities are often unstable simultaneously in the same plasma discharge, even on the same flux surface, unique parametric dependencies are discussed which may be useful for distinguishing the different mechanisms experimentally.

  5. Coherently driven, ultrafast electron-phonon dynamics in transport junctions

    SciTech Connect

    Szekely, Joshua E.; Seideman, Tamar

    2014-07-28

    Although the vast majority of studies of transport via molecular-scale heterojunctions have been conducted in the (static) energy domain, experiments are currently beginning to apply time domain approaches to the nanoscale transport problem, combining spatial with temporal resolution. It is thus an opportune time for theory to develop models to explore both new phenomena in, and new potential applications of, time-domain, coherently driven molecular electronics. In this work, we study the interaction of a molecular phonon with an electronic wavepacket transmitted via a conductance junction within a time-domain model that treats the electron and phonon on equal footing and spans the weak to strong electron-phonon coupling strengths. We explore interference between two coherent energy pathways in the electronic subspace, thus complementing previous studies of coherent phenomena in conduction junctions, where the stationary framework was used to study interference between spatial pathways. Our model provides new insights into phase decoherence and population relaxation within the electronic subspace, which have been conventionally treated by density matrix approaches that often rely on phenomenological parameters. Although the specific case of a transport junction is explored, our results are general, applying also to other instances of coupled electron-phonon systems.

  6. Loss of anion transport without increased sodium absorption characterizes newborn porcine cystic fibrosis airway epithelia

    PubMed Central

    Chen, Jeng-Haur; Stoltz, David A.; Karp, Philip H.; Ernst, Sarah E.; Pezzulo, Alejandro A.; Moninger, Thomas O.; Rector, Michael V.; Reznikov, Leah R.; Launspach, Janice L.; Chaloner, Kathryn; Zabner, Joseph; Welsh, Michael J.

    2011-01-01

    SUMMARY Defective transepithelial electrolyte transport is thought to initiate cystic fibrosis (CF) lung disease. Yet, how loss of CFTR affects electrolyte transport remains uncertain. CFTR−/− pigs spontaneously develop lung disease resembling human CF. At birth, their airways exhibit a bacterial host defense defect, but are not inflamed. Therefore, we studied ion transport in newborn nasal and tracheal/bronchial epithelia in tissue, cultures, and in vivo. CFTR−/− epithelia showed markedly reduced Cl− and HCO3− transport. However, in contrast to a widely held view, lack of CFTR did not increase transepithelial Na+ or liquid absorption or reduce periciliary liquid depth. Like human CF, CFTR−/− pigs showed increased amiloride-sensitive voltage and current, but lack of apical Cl− conductance caused the change, not increased Na+ transport. These results indicate that CFTR provides the predominant transcellular pathway for Cl− and HCO3− in porcine airway epithelia, and reduced anion permeability may initiate CF airway disease. PMID:21145458

  7. Transport Properties of III-N Hot Electron Transistors

    NASA Astrophysics Data System (ADS)

    Suntrup, Donald J., III

    Unipolar hot electron transistors (HETs) represent a tantalizing alternative to established bipolar transistor technologies. During device operation electrons are injected over a large emitter barrier into the base where they travel along the device axis with very high velocity. Upon arrival at the collector barrier, high-energy electrons pass over the barrier and contribute to collector current while low-energy electrons are quantum mechanically reflected back into the base. Designing the base with thickness equal to or less than the hot electron mean free path serves to minimize scattering events and thus enable quasi-ballistic operation. Large current gain is achieved by increasing the ratio of transmitted to reflected electrons. Although III-N HETs have undergone substantial development in recent years, there remain ample opportunities to improve key device metrics. In order to engineer improved device performance, a deeper understanding of the operative transport physics is needed. Fortunately, the HET provides fertile ground for studying several prominent electron transport phenomena. In this thesis we present results from several studies that use the III-N HET as both emitter and analyzer of hot electron momentum states. The first provides a measurement of the hot electron mean free path and the momentum relaxation rate in GaN; the second relies on a new technique called electron injection spectroscopy to investigate the effects of barrier height inhomogeneity in the emitter. To supplement our analysis we develop a comprehensive theory of coherent electron transport that allows us to model the transfer characteristics of complex heterojunctions. Such a model provides a theoretical touchstone with which to compare our experimental results. While these studies are of potential interest in their own right, we interpret the results with an eye toward improving next-generation device performance.

  8. Simulation of electron transport in quantum well devices

    NASA Technical Reports Server (NTRS)

    Miller, D. R.; Gullapalli, K. K.; Reddy, V. R.; Neikirk, D. P.

    1992-01-01

    Double barrier resonant tunneling diodes (DBRTD) have received much attention as possible terahertz devices. Despite impressive experimental results, the specifics of the device physics (i.e., how the electrons propagate through the structure) are only qualitatively understood. Therefore, better transport models are warranted if this technology is to mature. In this paper, the Lattice Wigner function is used to explain the important transport issues associated with DBRTD device behavior.

  9. Ray tracing and absorption of electron cyclotron waves in the L-2 stellarator

    SciTech Connect

    Goldfinger, R.C. ); Likin, K.M. . Inst. Obshchey Fiziki); Ochirov, B.D. . Inst. Avtomatiki i Ehlektrometrii)

    1991-01-01

    The absorption of electron cyclotron waves in L-2 stellarator plasmas has been investigated by adapting the RAYS geometrical optics code developed at Oak Ridge National Laboratory to the parameters of L-2. Two heating schemes were considered: Low-field launching of the ordinary wave at the fundamental resonance and low-field launching of the extraordinary wave at the second harmonic. Significant power absorption (up to 100%) of the extraordinary mode at the second harmonic resonance was obtained. A multipass absorption model was used to estimate the contribution to plasma heating of the power that remains after the first pass which is subsequently reflected from the vessel walls. Finally, results obtained with the RAYS code and with a code developed at the Institute of Automation and Electrometry were compared and found to be in good agreement. 6 refs., 4 figs.

  10. Nonlinear absorption of surface plasmons and emission of electrons from metallic targets

    SciTech Connect

    Singh, D. B.; Kumar, Gagan; Tripathi, V. K.

    2007-10-15

    A large-amplitude surface plasma wave (SPW) over a metal-vacuum interface Ohmically heats the electrons and undergoes nonlinear absorption. The attenuation rate increases with the local SPW amplitude. The enhanced electron temperature leads to stronger thermionic emission of electrons. At typical Nd:glass laser intensity I{sub L}=7 GW/cm{sup 2}, if one takes the amplitude of the SPW to be {approx_equal}6 times the amplitude of the laser, one obtains the thermionic electron emission current density J=200 A/cm{sup 2}. However, the emission current density decreases with propagation distance at a much faster rate than the SPW amplitude and electron temperature.

  11. Collisionless absorption, hot electron generation, and energy scaling in intense laser-target interaction

    SciTech Connect

    Liseykina, T.; Mulser, P.; Murakami, M.

    2015-03-15

    Among the various attempts to understand collisionless absorption of intense and superintense ultrashort laser pulses, a whole variety of models and hypotheses has been invented to describe the laser beam target interaction. In terms of basic physics, collisionless absorption is understood now as the interplay of the oscillating laser field with the space charge field produced by it in the plasma. A first approach to this idea is realized in Brunel's model the essence of which consists in the formation of an oscillating charge cloud in the vacuum in front of the target, therefore frequently addressed by the vague term “vacuum heating.” The investigation of statistical ensembles of orbits shows that the absorption process is localized at the ion-vacuum interface and in the skin layer: Single electrons enter into resonance with the laser field thereby undergoing a phase shift which causes orbit crossing and braking of Brunel's laminar flow. This anharmonic resonance acts like an attractor for the electrons and leads to the formation of a Maxwellian tail in the electron energy spectrum. Most remarkable results of our investigations are the Brunel like spectral hot electron distribution at the relativistic threshold, the minimum of absorption at Iλ{sup 2}≅(0.3−1.2)×10{sup 21} Wcm{sup −2}μm{sup 2} in the plasma target with the electron density of n{sub e}λ{sup 2}∼10{sup 23}cm{sup −3}μm{sup 2}, the drastic reduction of the number of hot electrons in this domain and their reappearance in the highly relativistic domain, and strong coupling, beyond expectation, of the fast electron jets with the return current through Cherenkov emission of plasmons. The hot electron energy scaling shows a strong dependence on intensity in the moderately relativistic domain Iλ{sup 2}≅(10{sup 18}−10{sup 20}) Wcm{sup −2}μm{sup 2}, a scaling in vague accordance with current published estimates in the range Iλ{sup 2}≅(0.14−3.5)×10{sup 21} Wcm{sup −2}

  12. Resonance Raman and temperature-dependent electronic absorption spectra of cavity and noncavity models of the hydrated electron

    PubMed Central

    Casey, Jennifer R.; Larsen, Ross E.; Schwartz, Benjamin J.

    2013-01-01

    Most of what is known about the structure of the hydrated electron comes from mixed quantum/classical simulations, which depend on the pseudopotential that couples the quantum electron to the classical water molecules. These potentials usually are highly repulsive, producing cavity-bound hydrated electrons that break the local water H-bonding structure. However, we recently developed a more attractive potential, which produces a hydrated electron that encompasses a region of enhanced water density. Both our noncavity and the various cavity models predict similar experimental observables. In this paper, we work to distinguish between these models by studying both the temperature dependence of the optical absorption spectrum, which provides insight into the balance of the attractive and repulsive terms in the potential, and the resonance Raman spectrum, which provides a direct measure of the local H-bonding environment near the electron. We find that only our noncavity model can capture the experimental red shift of the hydrated electron’s absorption spectrum with increasing temperature at constant density. Cavity models of the hydrated electron predict a solvation structure similar to that of the larger aqueous halides, leading to a Raman O–H stretching band that is blue-shifted and narrower than that of bulk water. In contrast, experiments show the hydrated electron has a broader and red-shifted O–H stretching band compared with bulk water, a feature recovered by our noncavity model. We conclude that although our noncavity model does not provide perfect quantitative agreement with experiment, the hydrated electron must have a significant degree of noncavity character. PMID:23382233

  13. Anomalous electronic transport in dual-nanostructured lead telluride.

    PubMed

    He, J Q; Sootsman, J R; Xu, L Q; Girard, S N; Zheng, J C; Kanatzidis, M G; Dravid, V P

    2011-06-15

    The Pb- and Sb- dual nanostructured PbTe system exhibits anomalous electronic transport behavior wherein the carrier mobility first increases and then decreases with increase in temperature. By combining in situ transmission electron microscopy observations and theoretical calculations based on energy filtering of charge carriers, we propose a plausible mechanism of charge transport based on interphase potential that is mediated by interdiffusion between coexisting Pb and Sb precipitates. These findings promise new strategies to enhance thermoelectric figure of merit via dual and multinanostructuring of miscible precipitates. PMID:21557606

  14. Excitonic emission and absorption resonances in V0.25W0.75Se2 single crystals grown by direct vapour transport technique

    NASA Astrophysics Data System (ADS)

    Solanki, G. K.; Pataniya, Pratik; Sumesh, C. K.; Patel, K. D.; Pathak, V. M.

    2016-05-01

    A systematic study on emission and absorption spectra of vanadium mixed tungsten diselenide single crystals grown by direct vapour transport (DVT) technique is reported. The grown crystals were characterized by energy dispersive analysis of X-ray (EDAX), which gives the confirmation about the stoichiometry. The structural characterizations were accomplished by X-ray diffraction (XRD), surface morphology and transmission electron microscopy (TEM). These characterizations were indicating the growth of V0.25W0.75Se2 single crystal from vapour phase. The optical response of this material has been observed by combination of UV-vis-NIR spectroscopy and photo luminescence (PL) spectroscopy. A detailed study of excitonic emission and absorption resonances was carried out on grown crystals. The energy band gap was calculated for indirect allowed transition with absorbed and emitted phonon. Additionally, absorption tail for grown crystal is found to obey the Urbach's rule.

  15. Electronic transport in polycrystalline samples of icosahedral phases

    NASA Astrophysics Data System (ADS)

    Vekilov, Yu. Kh.; Chernikov, M. A.; Dolinichek, Ya.

    2016-01-01

    The low-temperature electronic transport in polycrystals of quasicrystalline phases with an icosahedral structure has been analyzed within the model of the granular electronic system. In this model, the grains (drops) of a metallic icosahedral phase are surrounded by extended defects and grain boundaries, which create an insulating environment. The electron transport in this model is determined by the size quantization of electronic states inside metallic grains, by intergranular tunneling, and by electrostatic barriers. Depending on the temperature and structural state of the system, the hopping conductivity with variable lengths of jumps in the Efros-Shklovskii or Mott regime is observed with predominantly elastic cotunneling. In the case of strong intergranular coupling, the system passes into the metallic regime with the exponential temperature dependence of the electrical conductivity.

  16. Contactless electronic transport in a bio-molecular junction

    SciTech Connect

    Hossain, Faruque M. Al-Dirini, Feras; Skafidas, Efstratios

    2014-07-28

    Molecular electronics hold promise for next generation ultra-low power, nano-scale integrated electronics. The main challenge in molecular electronics is to make a reliable interface between molecules and metal electrodes. Interfacing metals and molecules detrimentally affects the characteristics of nano-scale molecular electronic devices. It is therefore essential to investigate alternative arrangements such as contact-less tunneling gaps wherever such configurations are feasible. We conduct ab initio density functional theory and non-equilibrium Green's functions calculations to investigate the transport properties of a biocompatible glycine molecular junction. By analyzing the localized molecular orbital energy distributions and transmission probabilities in the transport-gap, we find a glycine molecule confined between two gold electrodes, without making a contact, is energetically stable and possesses high tunneling current resembling an excellent ohmic-like interface.

  17. Aerosol Sources, Absorption, and Intercontinental Transport: Synergies among Models, Remote Sensing, and Atmospheric Measurements

    NASA Technical Reports Server (NTRS)

    Chin, Mian; Ginoux, Paul; Dubovik, Oleg; Holben, Brent; Kaufman, Yoram; chu, Allen; Anderson, Tad; Quinn, Patricia

    2003-01-01

    Aerosol climate forcing is one of the largest uncertainties in assessing the anthropogenic impact on the global climate system. This uncertainty arises from the poorly quantified aerosol sources, especially black carbon emissions, our limited knowledge of aerosol mixing state and optical properties, and the consequences of intercontinental transport of aerosols and their precursors. Here we use a global model GOCART to simulate atmospheric aerosols, including sulfate, black carbon, organic carbon, dust, and sea salt, from anthropogenic, biomass burning, and natural sources. We compare the model calculated aerosol extinction and absorption with those quantities from the ground-based sun photometer measurements from AERONET at several different wavelengths and the field observations from ACE-Asia, and model calculated total aerosol optical depth and fine mode fractions with the MODIS satellite retrieval. We will also estimate the intercontinental transport of pollution and dust aerosols from their source regions to other areas in different seasons.

  18. Aerosol Sources, Absorption, and Intercontinental Transport: Synergies Among Models, Remote Sensing, and Atmospheric Measurements

    NASA Technical Reports Server (NTRS)

    Chin, Mian; Chu, Allen; Levy, Robert; Remer, Lorraine; Kaufman, Yoram; Dubovik, Oleg; Holben, Brent; Eck, Tom; Anderson, Tad; Quinn, Patricia

    2004-01-01

    Aerosol climate forcing is one of the largest uncertainties in assessing the anthropogenic impact on the global climate system. This uncertainty arises from the poorly quantified aerosol sources, especially black carbon emissions, our limited knowledge of aerosol mixing state and optical properties, and the consequences of intercontinental transport of aerosols and their precursors. Here we use a global model GOCART to simulate atmospheric aerosols, including sulfate, black carbon, organic carbon, dust, and sea salt, from anthropogenic, .biomass burning, and natural sources. We compare the model calculated aerosol extinction and absorption with those quantities from the ground-based sun photometer measurements from AERON" at several different wavelengths and the field observations from ACE-Asia, and model calculated total aerosol optical depth and fine mode fractions with the MODIS satellite retrieval. We will also estimate the intercontinental transport of pollution and dust aerosols from their source regions to other areas in different seasons.

  19. Non equilibrium electronic transport in multilayered nanostructures

    NASA Astrophysics Data System (ADS)

    Cruz-Rojas, Jesus

    Recent advances in strongly correlated materials have produced systems with novel and interesting properties like high Tc superconductors, Mott insulators and others. These novel properties have sparked an interest in industry as well as in academia as new devices are being developed. One such kind of device that can be fabricated is a heterostructure, in which layers of different compounds are stacked in a single direction. Modern deposition techniques like electron beam epitaxy, in which atomic layers of different materials are deposited one at a time creating the device, are capable of fabricating heterostructures with atomic precision. We propose a technique to study heterostructures composed of strongly correlated materials out of equilibrium. By using the Keldysh Green's function formalism in the dynamical mean field theory (DMFT) framework the properties of a multilayered device are analyzed. The system is composed of infinite dimensional 2D lattices, stacked in the z direction. The first and last planes are then connected to a bulk reservoir, and several metallic planes are used to connect the bulk reservoir to the barrier region. The barrier region is the system of interest, also known as the device. The device is composed of a number of planes where the system correlations have been turned on. The correlations are then model by using the Falicov-Kimball Hamiltonian. The device is then connected to the bulk once again from the opposite side using metallic planes creating a symmetric system. In order to study the non equilibrium properties of the device a linear vector potential A(t) = A0 + tE is turned on a long time in the past for a unit of time and then turned off. This in turn will create a current in the bulk, in effect current biasing the device, as opposed to a voltage bias in which opposite sides of the device are held to a different potential. In this document we will explain the importance of the subject, we will derive and develop the algorithm

  20. Study of Electron Transport and Amplification in Diamond

    SciTech Connect

    Muller, Erik M.; Ben-Zvi, Ilan

    2013-03-31

    As a successful completion of this award, my group has demonstrated world-leading electron gain from diamond for use in a diamond-amplified photocathode. Also, using high-resolution photoemission measurements we were able to uncover exciting new physics of the electron emission mechanisms from hydrogen terminated diamond. Our work, through the continued support of HEP, has resulted in a greater understanding of the diamond material science, including current limits, charge transport modeling, and spatial uniformity.

  1. Origin of electronic transport of lithium phthalocyanine iodine crystal

    SciTech Connect

    Koike, Noritake; Oda, Masato; Shinozuka, Yuzo

    2013-12-04

    The electronic structures of Lithium Phthalocyanine Iodine are investigated using density functional theory. Comparing the band structures of several model crystals, the metallic conductivity of highly doped LiPcI{sub x} can be explained by the band of doped iodine. These results reveal that there is a new mechanism for electronic transport of doped organic semiconductors that the dopant band plays the main role.

  2. Two-stream approach to electron transport and thermalization

    SciTech Connect

    Stamnes, K.

    1981-04-01

    An explicit solution to the electron transport and energy degradation problem is presented in the two-stream approximation. The validity of this simple approach is discussed, and it is shown that it can be extended to high electron energies (appropriate for applications to auroras) provided the coupling between the two streams, described by the backscatter ratio, is correctly estimated. A simple formula for the backscatter ratio which can be used at all energies is derived.

  3. Simulation of electron transport during electron-beam-induced deposition of nanostructures

    PubMed Central

    Jeschke, Harald O; Valentí, Roser

    2013-01-01

    Summary We present a numerical investigation of energy and charge distributions during electron-beam-induced growth of tungsten nanostructures on SiO2 substrates by using a Monte Carlo simulation of the electron transport. This study gives a quantitative insight into the deposition of energy and charge in the substrate and in the already existing metallic nanostructures in the presence of the electron beam. We analyze electron trajectories, inelastic mean free paths, and the distribution of backscattered electrons in different compositions and at different depths of the deposit. We find that, while in the early stages of the nanostructure growth a significant fraction of electron trajectories still interacts with the substrate, when the nanostructure becomes thicker the transport takes place almost exclusively in the nanostructure. In particular, a larger deposit density leads to enhanced electron backscattering. This work shows how mesoscopic radiation-transport techniques can contribute to a model that addresses the multi-scale nature of the electron-beam-induced deposition (EBID) process. Furthermore, similar simulations can help to understand the role that is played by backscattered electrons and emitted secondary electrons in the change of structural properties of nanostructured materials during post-growth electron-beam treatments. PMID:24367747

  4. Multiphoton absorption in germanium using pulsed infrared free-electron laser radiation

    NASA Astrophysics Data System (ADS)

    Seo, D.; Gregory, J. M.; Feldman, L. C.; Tolk, N. H.; Cohen, P. I.

    2011-05-01

    We report wavelength- and intensity-dependent transmission measurements of intense mid-infrared radiation from the Vanderbilt free-electron laser in single-crystal Ge(100) in the wavelength range of 2.8-5.2 μm. This range accesses both the direct and indirect energy gaps in Ge, requiring in each case either two or three photons (2PA or 3PA) for absorption. Large changes in the multiphoton absorption rate are seen at the direct-to-indirect and 2PA-to-3PA transitions. Photon interactions are dominated by free-carrier absorption (FCA), primarily due to holes. The entire absorption process is modeled with the two- and three-photon absorption coefficients (β and γ) as fitting parameters. Using newly measured values of the low-intensity FCA cross sections, we find a best fit to the data at 2.8 μm that is in agreement with theory and previous measurements. We report a ratio of 175 for β across the direct-to-indirect transition, and a ratio of 5 across the same transition for γ. These ratios are independent of systematic variations in free-carrier cross sections and beam diameter.

  5. Electron transport in magnetrons by a posteriori Monte Carlo simulations

    NASA Astrophysics Data System (ADS)

    Costin, C.; Minea, T. M.; Popa, G.

    2014-02-01

    Electron transport across magnetic barriers is crucial in all magnetized plasmas. It governs not only the plasma parameters in the volume, but also the fluxes of charged particles towards the electrodes and walls. It is particularly important in high-power impulse magnetron sputtering (HiPIMS) reactors, influencing the quality of the deposited thin films, since this type of discharge is characterized by an increased ionization fraction of the sputtered material. Transport coefficients of electron clouds released both from the cathode and from several locations in the discharge volume are calculated for a HiPIMS discharge with pre-ionization operated in argon at 0.67 Pa and for very short pulses (few µs) using the a posteriori Monte Carlo simulation technique. For this type of discharge electron transport is characterized by strong temporal and spatial dependence. Both drift velocity and diffusion coefficient depend on the releasing position of the electron cloud. They exhibit minimum values at the centre of the race-track for the secondary electrons released from the cathode. The diffusion coefficient of the same electrons increases from 2 to 4 times when the cathode voltage is doubled, in the first 1.5 µs of the pulse. These parameters are discussed with respect to empirical Bohm diffusion.

  6. Imaging electronic trap states in perovskite thin films with combined fluorescence and femtosecond transient absorption microscopy

    DOE PAGES

    Xiao, Kai; Ma, Ying -Zhong; Simpson, Mary Jane; Doughty, Benjamin; Yang, Bin

    2016-04-22

    Charge carrier trapping degrades the performance of organometallic halide perovskite solar cells. To characterize the locations of electronic trap states in a heterogeneous photoactive layer, a spatially resolved approach is essential. Here, we report a comparative study on methylammonium lead tri-iodide perovskite thin films subject to different thermal annealing times using a combined photoluminescence (PL) and femtosecond transient absorption microscopy (TAM) approach to spatially map trap states. This approach coregisters the initially populated electronic excited states with the regions that recombine radiatively. Although the TAM images are relatively homogeneous for both samples, the corresponding PL images are highly structured. Themore » remarkable variation in the PL intensities as compared to transient absorption signal amplitude suggests spatially dependent PL quantum efficiency, indicative of trapping events. Furthermore, detailed analysis enables identification of two trapping regimes: a densely packed trapping region and a sparse trapping area that appear as unique spatial features in scaled PL maps.« less

  7. Calculation of Electronic Absorption Spectra with Account of Thermal Geometry Fluctuations

    NASA Astrophysics Data System (ADS)

    Guzha, Maris V.; Svitenkov, Andrew I.

    2016-08-01

    An influence of thermal fluctuations of molecule's geometry on calculated electronic-absorption Vis/Uv spectra is considered. Paper presents the quantum chemical modeling of the electronic-absorption spectra for the collection of graphene samples (44, 56, 60, 68 atoms). The calculations were performed by time dependent density functional theory (TDDFT) method in combination with molecular dynamics (MD) simulation at T=300 K. The noticeable changing of spectra relative to single point TDDFT calculation was discovered for two of four structures. We associate achieved results with perturbation of hydrogen and carbon atoms on the edges of the structures. We believe that suggested methodology will be useful in application engineering researches of novel molecules and molecular complexes.

  8. Absorption and Diffusion Measurements of Biological Samples using a THz Free Electron Laser.

    PubMed

    Giovenale, E; D'Arienzo, M; Doria, A; Gallerano, G P; Lai, A; Messina, G; Piccinelli, D

    2003-06-01

    A compact THz Free Electron Laser (FEL) isbeing used to perform irradiation ofbiological samples to investigate possiblegenotoxic effects. In order to evaluate theexact radiation dose absorbed by the singlecomponents of the samples it is necessaryto study the optical properties of thesamples, separating the contributions tothe radiation attenuation coefficientcoming from absorption and from diffusion.Spectroscopic measurements have beenperformed on different biological samples, comparing the experimental results withtheoretical models. PMID:23345832

  9. An analysis of pollutant gas transport and absorption in pulmonary airways.

    PubMed

    Grotberg, J B; Sheth, B V; Mockros, L F

    1990-05-01

    A mathematical model of ozone absorption, or for any soluble gas that has similar transport properties, is developed for a branching network of liquid-lined cylinders. In particular, we investigate specific flow regimes for finite length tubes where boundary layer phenomena and entrance effects exist in high Reynolds and Peclet (Pe) number airways. The smaller airways which have lower Reynolds and Peclet number flows are modelled by incorporating the detailed analysis found in [10] and modifying it for airways which have alveolated surfaces. We also consider a reacting gas and treat specific regimes where the reaction front is located at the air-liquid interface, within the liquid or at the liquid-tissue interface. Asymptotic methods are used in regions of the tracheobronchial tree where Pe much less than 1 and Pe much greater than 1. In addition, the fact that the radial transport parameter gamma much less than 1 for this toxin, and others such as nitrous oxides, is employed to simplify the analysis. The ozone concentrations, airway absorption and tissue dose are examined as a function of airway generation for several values of the governing parameters. The general result is a maximal dosing in airway generations 17 to 18 that is much larger (up to an order of magnitude) than the predictions of previous theories.

  10. Soft X-Ray Absorption Spectroscopy at an X-ray Free Electron Laser

    NASA Astrophysics Data System (ADS)

    Higley, Daniel; Schlotter, William; Turner, Joshua; Moeller, Stefan; Mitra, Ankush; Tsukamoto, Arata; Marvel, Robert; Haglund, Richard; Durr, Hermann; Stohr, Joachim; Dakovski, Georgi

    2015-03-01

    X-ray free electron lasers, providing coherent, ultrafast, high intensity x-ray pulses, have enabled groundbreaking scattering experiments to probe the atomic structure of materials on femtosecond timescales. Nonetheless, x-ray absorption spectroscopy (XAS), one of the most fundamental and common x-ray techniques practiced at synchrotron light sources, has proven challenging to conduct with satisfactory signal-to-noise levels at soft x-ray energies using free electron laser sources. The ability to routinely collect high quality XAS spectra, especially in a time-resolved manner, will open many new scientific possibilities in the areas of ultrafast demagnetization, phase transitions and chemical dynamics to highlight a few. Here, we report how XAS using total fluorescence yield detection yields high signal-to-noise x-ray absorption spectra at an x-ray free electron laser source. Data were collected over multiple absorption edges on technologically relevant materials. These measurements were recorded on the Soft X-Ray Materials Science instrument at the Linac Coherent Light Source. The results are easily extendable to time-resolved measurements.

  11. Excited state X-ray absorption spectroscopy: Probing both electronic and structural dynamics

    NASA Astrophysics Data System (ADS)

    Neville, Simon P.; Averbukh, Vitali; Ruberti, Marco; Yun, Renjie; Patchkovskii, Serguei; Chergui, Majed; Stolow, Albert; Schuurman, Michael S.

    2016-10-01

    We investigate the sensitivity of X-ray absorption spectra, simulated using a general method, to properties of molecular excited states. Recently, Averbukh and co-workers [M. Ruberti et al., J. Chem. Phys. 140, 184107 (2014)] introduced an efficient and accurate L 2 method for the calculation of excited state valence photoionization cross-sections based on the application of Stieltjes imaging to the Lanczos pseudo-spectrum of the algebraic diagrammatic construction (ADC) representation of the electronic Hamiltonian. In this paper, we report an extension of this method to the calculation of excited state core photoionization cross-sections. We demonstrate that, at the ADC(2)x level of theory, ground state X-ray absorption spectra may be accurately reproduced, validating the method. Significantly, the calculated X-ray absorption spectra of the excited states are found to be sensitive to both geometric distortions (structural dynamics) and the electronic character (electronic dynamics) of the initial state, suggesting that core excitation spectroscopies will be useful probes of excited state non-adiabatic dynamics. We anticipate that the method presented here can be combined with ab initio molecular dynamics calculations to simulate the time-resolved X-ray spectroscopy of excited state molecular wavepacket dynamics.

  12. Theoretical electronic absorption and natural circular dichroism spectra of (-)-trans-cyclooctene

    NASA Astrophysics Data System (ADS)

    Pedersen, Thomas Bondo; Koch, Henrik

    2000-02-01

    Using the random phase approximation and coupled cluster singles and doubles linear response theory in conjunction with two basis sets of augmented double-zeta quality and two nuclear geometries, we have calculated electronic absorption and natural circular dichroism spectra of (-)-trans-cyclooctene. We present a density functional theory optimized nuclear geometry whose ground state electric dipole moment and harmonic vibrational spectrum compare well with experimental data. The coupled cluster results obtained with this nuclear geometry are in good agreement with experimental electronic spectra, although the original interpretation of the most intense low-lying band as a π→π* transition is contradicted.

  13. Theoretical modeling of low-energy electronic absorption bands in reduced cobaloximes

    DOE PAGES

    Bhattacharjee, Anirban; Chavarot-Kerlidou, Murielle; Dempsey, Jillian L.; Gray, Harry B.; Fujita, Etsuko; Muckerman, James T.; Fontecave, Marc; Artero, Vincent; Arantes, Guilherme M.; Field, Martin J.

    2014-08-11

    Here, we report that the reduced Co(I) states of cobaloximes are powerful nucleophiles that play an important role in the hydrogen-evolving catalytic activity of these species. In this work we have analyzed the low energy electronic absorption bands of two cobaloxime systems experimentally and using a variety of density functional theory and molecular orbital ab initio quantum chemical approaches. Overall we find a reasonable qualitative understanding of the electronic excitation spectra of these compounds but show that obtaining quantitative results remains a challenging task.

  14. Theoretical modeling of low-energy electronic absorption bands in reduced cobaloximes

    SciTech Connect

    Bhattacharjee, Anirban; Chavarot-Kerlidou, Murielle; Dempsey, Jillian L.; Gray, Harry B.; Fujita, Etsuko; Muckerman, James T.; Fontecave, Marc; Artero, Vincent; Arantes, Guilherme M.; Field, Martin J.

    2014-08-11

    Here, we report that the reduced Co(I) states of cobaloximes are powerful nucleophiles that play an important role in the hydrogen-evolving catalytic activity of these species. In this work we have analyzed the low energy electronic absorption bands of two cobaloxime systems experimentally and using a variety of density functional theory and molecular orbital ab initio quantum chemical approaches. Overall we find a reasonable qualitative understanding of the electronic excitation spectra of these compounds but show that obtaining quantitative results remains a challenging task.

  15. Remote plasmon-induced heat transfer probed by the electronic transport of a gold nanowire

    NASA Astrophysics Data System (ADS)

    Mennemanteuil, M.-M.; Buret, M.; Cazier, N.; Colas-Des-Francs, G.; Bouhelier, A.; Besbes, M.; Ben-Abdallah, P.

    2016-07-01

    We show in this paper that the heat generated by the optical excitation of resonant plasmonic antennas and diffusing along a simple glass/air interface disturbs the electron transport of a nearby conductive element. By probing the temperature-dependent resistance of a gold nanowire Rnw(T ) , we quantitatively analyze the impact of a resonant absorption of the laser by the antennas. We find that the temperature rise at the nanowire induced by the laser absorption of a distant nanoparticle may exceed that of a direct illumination of the nanowire itself. We also find that a global calibration of the temperature-dependent resistance underestimates the heat generated locally by the laser. The local temperatures deduced from resistance variations are verified by numerical simulations with a very satisfactory agreement.

  16. Quercetin inhibits intestinal iron absorption and ferroportin transporter expression in vivo and in vitro.

    PubMed

    Lesjak, Marija; Hoque, Rukshana; Balesaria, Sara; Skinner, Vernon; Debnam, Edward S; Srai, Surjit K S; Sharp, Paul A

    2014-01-01

    Balancing systemic iron levels within narrow limits is critical for maintaining human health. There are no known pathways to eliminate excess iron from the body and therefore iron homeostasis is maintained by modifying dietary absorption so that it matches daily obligatory losses. Several dietary factors can modify iron absorption. Polyphenols are plentiful in human diet and many compounds, including quercetin--the most abundant dietary polyphenol--are potent iron chelators. The aim of this study was to investigate the acute and longer-term effects of quercetin on intestinal iron metabolism. Acute exposure of rat duodenal mucosa to quercetin increased apical iron uptake but decreased subsequent basolateral iron efflux into the circulation. Quercetin binds iron between its 3-hydroxyl and 4-carbonyl groups and methylation of the 3-hydroxyl group negated both the increase in apical uptake and the inhibition of basolateral iron release, suggesting that the acute effects of quercetin on iron transport were due to iron chelation. In longer-term studies, rats were administered quercetin by a single gavage and iron transporter expression measured 18 h later. Duodenal FPN expression was decreased in quercetin-treated rats. This effect was recapitulated in Caco-2 cells exposed to quercetin for 18 h. Reporter assays in Caco-2 cells indicated that repression of FPN by quercetin was not a transcriptional event but might be mediated by miRNA interaction with the FPN 3'UTR. Our study highlights a novel mechanism for the regulation of iron bioavailability by dietary polyphenols. Potentially, diets rich in polyphenols might be beneficial for patients groups at risk of iron loading by limiting the rate of intestinal iron absorption. PMID:25058155

  17. Quercetin Inhibits Intestinal Iron Absorption and Ferroportin Transporter Expression In Vivo and In Vitro

    PubMed Central

    Balesaria, Sara; Skinner, Vernon; Debnam, Edward S.; Srai, Surjit K. S.; Sharp, Paul A.

    2014-01-01

    Balancing systemic iron levels within narrow limits is critical for maintaining human health. There are no known pathways to eliminate excess iron from the body and therefore iron homeostasis is maintained by modifying dietary absorption so that it matches daily obligatory losses. Several dietary factors can modify iron absorption. Polyphenols are plentiful in human diet and many compounds, including quercetin – the most abundant dietary polyphenol – are potent iron chelators. The aim of this study was to investigate the acute and longer-term effects of quercetin on intestinal iron metabolism. Acute exposure of rat duodenal mucosa to quercetin increased apical iron uptake but decreased subsequent basolateral iron efflux into the circulation. Quercetin binds iron between its 3-hydroxyl and 4-carbonyl groups and methylation of the 3-hydroxyl group negated both the increase in apical uptake and the inhibition of basolateral iron release, suggesting that the acute effects of quercetin on iron transport were due to iron chelation. In longer-term studies, rats were administered quercetin by a single gavage and iron transporter expression measured 18 h later. Duodenal FPN expression was decreased in quercetin-treated rats. This effect was recapitulated in Caco-2 cells exposed to quercetin for 18 h. Reporter assays in Caco-2 cells indicated that repression of FPN by quercetin was not a transcriptional event but might be mediated by miRNA interaction with the FPN 3′UTR. Our study highlights a novel mechanism for the regulation of iron bioavailability by dietary polyphenols. Potentially, diets rich in polyphenols might be beneficial for patients groups at risk of iron loading by limiting the rate of intestinal iron absorption. PMID:25058155

  18. Transport Experiments on 2D Correlated Electron Physics in Semiconductors

    SciTech Connect

    Tsui, Daniel

    2014-03-24

    This research project was designed to investigate experimentally the transport properties of the 2D electrons in Si and GaAs, two prototype semiconductors, in several new physical regimes that were previously inaccessible to experiments. The research focused on the strongly correlated electron physics in the dilute density limit, where the electron potential energy to kinetic energy ratio rs>>1, and on the fractional quantum Hall effect related physics in nuclear demagnetization refrigerator temperature range on samples with new levels of purity and controlled random disorder.

  19. Electron energy transport and magnetic curvature driven modes

    SciTech Connect

    Coppi, B.; Tang, W.M.

    1984-10-01

    A transport coefficient for anomalous electron thermal conduction is constructed on the basis of the so-called Principle of Profile Consistency. It is assumed that the relevant modes in plasma where a substantial fraction of the electron population is magnetically trapped produce magnetic reconnection at a microscopic level and are driven by the combined effects of the plasma pressure gradient and the magnetic field curvature. Consequently, the scaling for the electron energy confinement time exhibits a strongly favorable dependence on the radius of magnetic curvature.

  20. Significance of active ion transport in transalveolar water absorption: a study on isolated rat lung.

    PubMed

    Basset, G; Crone, C; Saumon, G

    1987-03-01

    1. Experiments were performed on isolated rat lungs perfused with Ringer solutions containing red cells. The goal was to clarify the role of active transport of Na+ for the absorption of fluid across the alveolar membrane, and to characterize active and passive pathways. 2. Partially degassed lungs were filled with 5 ml of an isotonic Ringer solution containing 125I-labelled albumin in order to calculate the fluid movement, and 22Na+ or 36Cl- for measurement of ion fluxes. Passive non-electrolyte permeability was determined in all experiments using [3H]mannitol. 3. The average rate of fluid absorption in phosphate-buffered instillates was 134 nl/s (S.E., 18.5; n = 14). With ouabain (10(-4) M) in the perfusate the fluid absorption rate fell to 57 nl/s (S.E., 8.2; n = 18). Amiloride (10(-3)-10(-4) M) in the instillate reduced the absorption to 75 nl/s (S.E., 8.6; n = 16). These results show that fluid absorption depends on transcellular transport of Na+ and that alveolar epithelial cells have a Na+ entry system in the luminal membrane and a Na+-K+ pump in the abluminal membrane. 4. The transcellular ion transport operates in parallel with a paracellular, passive leak that allows mannitol to pass with a permeability surface area product of 1.2 X 10(-4) ml/s, corresponding to a permeability coefficient of 2.4 X 10(-8) cm/s, assuming an alveolar surface area of 5000 cm2. 5. The passive fluxes of Na+ were 9.4 pmol/(cm2s) (S.E., 1.3; n = 25) in the direction from alveoli to perfusate and 8.0 pmol/(cm2s) (S.E., 0.86; n = 6) from perfusate to plasma. The passive fluxes of Cl- in the two directions were not significantly different either. Thus the transalveolar electrical potential difference is too small to affect ion movements measurably. 6. The passive permeability to Na+ was 6.7 X 10(-8) cm/s and to Cl- was 10.2 X 10(-8) cm/s (alveolar surface area assumed to be 5000 cm2). The ratio of the permeabilities is close to the ratio of the diffusion coefficients in free

  1. Investigation of electron beam transport in a helical undulator

    SciTech Connect

    Jeong, Y.U.; Lee, B.C.; Kim, S.K.

    1995-12-31

    Lossless transport of electrons through the undulator is essential for CW operation of the FELs driven by recirculating electrostatic accelerators. We calculate the transport ratio of an electron beam in a helical undulator by using a 3-D simulation code and compare the results with the experimental results. The energy and the current of the electron beam are 400 keV and 2 A, respectively. The 3-D distribution of the magnetic field of a practical permanent-magnet helical undulator is measured and is used in the calculations. The major parameters of the undutlator are : period = 32 mm, number of periods = 20, number of periods in adiabatic region = 3.5, magnetic field strength = 1.3 kG. The transport ratio is very sensitive to the injection condition of the electron beam such as the emittance, the diameter, the divergence, etc.. The injection motion is varied in the experiments by changing the e-gun voltage or the field strength of the focusing magnet located at the entrance of the undulator. It is confirmed experimentally and with simulations that most of the beam loss occurs at the adiabatic region of the undulator regardless of the length of the adiabatic region The effect of axial guiding magnetic field on the beam finish is investigated. According to the simulations, the increase of the strength of axial magnetic field from 0 to 1 kG results in the increase of the transport ratio from 15 % to 95%.

  2. ELECTRONIC AND TRANSPORT PROPERTIES OF THERMOELECTRIC Ru2Si3

    NASA Astrophysics Data System (ADS)

    Singh, David J.; Parker, David

    2013-10-01

    We report calculations of the doping and temperature dependent thermopower of Ru2Si3 based on Boltzmann transport theory and the first principles electronic structure. We find that the performance reported to date can be significantly improved by optimization of the doping level and that ultimately n-type should have higher ZT than p-type.

  3. Requirement for Coenzyme Q in Plasma Membrane Electron Transport

    NASA Astrophysics Data System (ADS)

    Sun, I. L.; Sun, E. E.; Crane, F. L.; Morre, D. J.; Lindgren, A.; Low, H.

    1992-12-01

    Coenzyme Q is required in the electron transport system of rat hepatocyte and human erythrocyte plasma membranes. Extraction of coenzyme Q from the membrane decreases NADH dehydrogenase and NADH:oxygen oxidoreductase activity. Addition of coenzyme Q to the extracted membrane restores the activity. Partial restoration of activity is also found with α-tocopherylquinone, but not with vitamin K_1. Analogs of coenzyme Q inhibit NADH dehydrogenase and oxidase activity and the inhibition is reversed by added coenzyme Q. Ferricyanide reduction by transmembrane electron transport from HeLa cells is inhibited by coenzyme Q analogs and restored with added coenzyme Q10. Reduction of external ferricyanide and diferric transferrin by HeLa cells is accompanied by proton release from the cells. Inhibition of the reduction by coenzyme Q analogs also inhibits the proton release, and coenzyme Q10 restores the proton release activity. Trans-plasma membrane electron transport stimulates growth of serum-deficient cells, and added coenzyme Q10 increases growth of HeLa (human adenocarcinoma) and BALB/3T3 (mouse fibroblast) cells. The evidence is consistent with a function for coenzyme Q in a trans-plasma membrane electron transport system which influences cell growth.

  4. Ozone absorption spectroscopy in search of low-lying electronic states

    NASA Technical Reports Server (NTRS)

    Anderson, S. M.; Mauersberger, K.

    1995-01-01

    A spectrometer capable of detecting ozone absorption features 9 orders of magnitude weaker than the Hartley band has been employed to investigate the molecule's near-infrared absorption spectrum. At this sensitivity a wealth of information on the low-lying electronically excited states often believed to play a role in atmospheric chemistry is available in the form of vibrational and rotational structure. We have analyzed these spectra using a combination of digital filtering and isotope substitution and find evidence for three electronically excited states below 1.5 eV. The lowest of these states is metastable, bound by approximately 0.1 eV and probably the (3)A2 rather than the (3)B2 state. Its adiabatic electronic energy is 1.24 +/- 0.01 eV, slightly above the dissociation energy of the ground state. Two higher states, at 1.29 +/- 0.03 and 1.48 +/- 0.03 eV are identified as the (3)B2 and the (3)B1, respectively. Combined with other recent theoretical and experimental data on the low-lying electronic states of ozone, these results imply that these are, in fact, the lowest three excited states; that is, there are no electronically excited states of ozone lying below the energy of O(3P) + O2((3)Sigma(-), v = 0). Some of the implications for atmospheric chemistry are considered.

  5. Electronic topological transition in zinc under pressure: An x-ray absorption spectroscopy study

    NASA Astrophysics Data System (ADS)

    Aquilanti, G.; Trapananti, A.; Minicucci, M.; Liscio, F.; Twaróg, A.; Principi, E.; Pascarelli, S.

    2007-10-01

    Zinc metal has been studied at high pressure using x-ray absorption spectroscopy. In order to investigate the role of the different degrees of hydrostaticity on the occurrence of structural anomalies following the electronic topological transition, two pressure transmitting media have been used. Results show that the electronic topological transition, if it exists, does not induce an anomaly in the local environment of compressed Zn as a function of hydrostatic pressure and any anomaly must be related to a loss of hydrostaticity of the pressure transmitting medium. The near-edge structures of the spectra, sensitive to variations in the electronic density of states above the Fermi level, do not show any evidence of electronic transition whatever pressure transmitting medium is used.

  6. Electronic absorption spectra of linear and cyclic Cn+ n=7-9 in a neon matrix

    NASA Astrophysics Data System (ADS)

    Fulara, Jan; Shnitko, Ivan; Batalov, Anton; Maier, John P.

    2005-07-01

    The Cn+n=7-9 cations were produced by electron-impact ionization of perchloronaphthalene, mass selected, and their electronic absorption spectra in 6K neon matrices recorded. The linear and cyclic isomers of C7+ and C8+ are detected. Three systems of linear C7+ are observed with origin bands near 770, 332, and 309nm. The cyclic C7+ shows two transitions near 676 and 448nm. One system of linear C9+ is observed commencing at 371nm. Linear C8+ shows five dipole-allowed electronic transitions from the X˜Πg2 ground state, and the strongest ones have the origin bands at 890.8 and 308.1nm. Five electronic transitions of cyclic C8+ are also discernible.

  7. Experimental investigation on electron cyclotron absorption at down-shifted frequency in the PLT tokamak

    SciTech Connect

    Mazzucato, E.; Fidone, I.; Cavallo, A.; von Goeler, S.; Hsuan, H.

    1986-05-01

    The absorption of 60 GHz electron cyclotron waves, with the extraordinary mode and an oblique angle of propagation, has been investigated in the PLT tokamak in the regime of down-shifted frequencies. The production of energetic electrons, with energies of up to 300 to 400 keV, peaks at values of toroidal field (approx. =29 kG) for which the wave frequency is significantly smaller than the electron cyclotron frequency in the whole plasma region. The observations are consistent with the predictions of the relativistic theory of electron cyclotron damping at down-shifted frequency. Existing rf sources make this process a viable method for assisting the current ramp-up, and for heating the plasma of present large tokamaks.

  8. Ab-initio calculations of the hydrogen-uranium system. Part I: Surface phenomena, absorption, transport and trapping

    SciTech Connect

    Taylor, Christopher D; Lillard, R Scott

    2009-01-01

    Density functional theory was applied to the initial steps of uranium hydriding: surface phenomena, absorption, bulk transport and trapping. H adsorbs exothermically to the (0 0 1) surface, yet H absorption into the bulk is endothermic, with off-center octahedral absorption having the lowest absorption energy of 0.39 eV, relative to molecular H{sub 2}. H absorption in interstitial sites causes a local softening of the bulk modulus. Diffusion of H in unstrained {alpha}-U has a barrier of 0.6 eV. The energy of H absorption adjacent to the chemical impurities C, S, Si was lowered by an amount proportional to the size of the impurity atom, and the resulting lattice strain Si > S > C. Thus, impurities may promote hydriding by providing surfaces or prestrained zones for H uptake.

  9. Neoclassical electron and ion transport in toroidally rotating plasmas

    SciTech Connect

    Sugama, H.; Horton, W.

    1997-06-01

    Neoclassical transport processes of electrons and ions are investigated in detail for toroidally rotating axisymmetric plasmas with large flow velocities on the order of the ion thermal speed. The Onsager relations for the flow-dependent neoclassical transport coefficients are derived from the symmetry properties of the drift kinetic equation with the self-adjoint collision operator. The complete neoclassical transport matrix with the Onsager symmetry is obtained for the rotating plasma consisting of electrons and single-species ions in the Pfirsch{endash}Schl{umlt u}ter and banana regimes. It is found that the inward banana fluxes of particles and toroidal momentum are driven by the parallel electric field, which are phenomena coupled through the Onsager symmetric off-diagonal coefficients to the parallel currents caused by the radial thermodynamic forces conjugate to the inward fluxes, respectively. {copyright} {ital 1997 American Institute of Physics.}

  10. Relativistic electron transport and bremsstrahlung production in solar flares

    NASA Astrophysics Data System (ADS)

    Miller, James A.; Ramaty, Reuven

    1989-09-01

    A Monte Carlo simulation of ultrarelativistic electron transport in solar flare magnetic loops has been developed. It includes Coulomb, synchrotron, and bremsstrahlung energy losses; pitch-angle scattering by Alfven and whistler turbulence in the coronal region of the loop; and magnetic mirroring in the converging magnetic flux tubes beneath the transition region. Depth distributions, time profiles, energy spectra, and angular distributions of the resulting bremsstrahlung emission are calculated. It is found that both the preferential detection of solar flares with greater than 10 MeV emission near the limb of the sun and the observation of ultrarelativistic electron bremsstrahlung from flares on the disk are consequences of the loop transport model. The declining portions of the observed time profiles of greater than 10 MeV emission from solar flares can also be accounted for, and it is proposed that these portions are determined by transport and not acceleration.

  11. Energy-filtered Electron Transport Structures for Low-power Low-noise 2-D Electronics

    PubMed Central

    Pan, Xuan; Qiu, Wanzhi; Skafidas, Efstratios

    2016-01-01

    In addition to cryogenic techniques, energy filtering has the potential to achieve high-performance low-noise 2-D electronic systems. Assemblies based on graphene quantum dots (GQDs) have been demonstrated to exhibit interesting transport properties, including resonant tunnelling. In this paper, we investigate GQDs based structures with the goal of producing energy filters for next generation lower-power lower-noise 2-D electronic systems. We evaluate the electron transport properties of the proposed GQD device structures to demonstrate electron energy filtering and the ability to control the position and magnitude of the energy passband by appropriate device dimensioning. We also show that the signal-to-thermal noise ratio performance of the proposed nanoscale device can be modified according to device geometry. The tunability of two-dimensional GQD structures indicates a promising route for the design of electron energy filters to produce low-power and low-noise electronics. PMID:27796343

  12. Electron transport mechanisms in polymer-carbon sphere composites

    NASA Astrophysics Data System (ADS)

    Nieves, Cesar A.; Ramos, Idalia; Pinto, Nicholas J.; Zimbovskaya, Natalya A.

    2016-07-01

    A set of uniform carbon microspheres (CSs) whose diameters have the order of 0.125 μm to 10 μm was prepared from aqueous sucrose solution by means of hydrothermal carbonization of sugar molecules. A pressed pellet was composed by mixing CSs with polyethylene oxide (PEO). Electrical characterization of the pellet was carried out showing Ohmic current-voltage characteristics and temperature-dependent conductivity in the range of 80 K electron transport. It was shown that thermally induced electron tunneling between adjacent spheres may take on an important part in the electron transport through the CS/PEO composites.

  13. Electron transport in naphthylamine-based organic compounds

    NASA Astrophysics Data System (ADS)

    Tse, S. C.; Kwok, K. C.; So, S. K.

    2006-12-01

    Two naphthylamine-based hole transporters, namely, N ,N'-diphenyl-N ,N'-bis(1-naphthyl)(1,1'-biphenyl)-4,4'diamine (NPB) and 4,4',4″-tris(n-(2-naphthyl)-n-phenyl-amino)-triphenylamine (2TNATA), were found to possess electron transporting (ET) abilities. From time-of-flight measurements, values of electron mobilities for NPB and 2TNATA are (6-9)×10-4 and (1-3)×10-4cm2/Vs, respectively, under an applied electric field range of 0.04-0.8MV/cm at 290K. An organic light-emitting diode that employed NPB as the ET material was demonstrated. The electron conducting mechanism of NPB and 2TNATA in relation to the Marcus theory [Rev. Mod. Phys. 65, 599 (1993)] from quantum chemistry will be discussed.

  14. Electronic transport experiments on osmium-adatom-decorated graphene

    NASA Astrophysics Data System (ADS)

    Elias, Jamie; Henriksen, Erik

    Monolayer graphene is theoretically predicted to inherit a spin-orbit coupling from a dilute coating of certain transition metal adatoms. To explore these predictions we have constructed a cryogenic probe capable of in situ thermal annealing of graphene followed immediately by electronic transport measurements and controlled deposition of sub-monolayer coatings of most any metal. Previously a light coating of indium on graphene was investigated, and found to transfer electrons to graphene and reduce the mobility although no evidence of an induced spin-orbit coupling was seen. We are now depositing osmium and tungsten on graphene devices. Our initial results show an unexpected hole-doping and a sizable increase in resistance of the sample. We will report our progress on characterizing these samples by electronic transport measurements.

  15. The role of sodium-dependent glucose transporter 1 and glucose transporter 2 in the absorption of cyanidin-3-o-β-glucoside in Caco-2 cells.

    PubMed

    Zou, Tang-Bin; Feng, Dan; Song, Gang; Li, Hua-Wen; Tang, Huan-Wen; Ling, Wen-Hua

    2014-10-01

    Anthocyanins have multiple biological activities of benefit to human health. While a few studies have been conducted to evaluate the bioavailability of anthocyanins, the mechanisms of their absorption mechanism remain ill-defined. In the present study, we investigated the absorption mechanism of cyanidin-3-O-β-glucoside (Cy-3-G) in human intestinal epithelial (Caco-2) cells. Cy-3-G transport was assessed by measuring the absorptive and efflux direction. Inhibition studies were conducted using the pharmacological agents, phloridzin, an inhibitor of sodium-dependent glucose transporter 1 (SGLT1), or phloretin, an inhibitor of glucose transporter 2 (GLUT2). The results showed that phloridzin and phloretin significantly inhibited the absorption of Cy-3-G. In addition, Caco-2 cells transfected with small interfering RNA (siRNA) specific for SGLT1 or GLUT2 showed significantly decreased Cy-3-G absorption. These siRNA transfected cells also showed a significantly decreased rate of transport of Cy-3-G compared with the control group. These findings suggest that Cy-3-G absorption is dependent on the activities of SGLT1 and GLUT2 in the small intestine and that SGLT1 and GLUT2 could be a limiting step for the bioavailability of Cy-3-G. PMID:25314643

  16. Transport in nanoscale systems: hydrodynamics, turbulence, and local electron heating

    NASA Astrophysics Data System (ADS)

    di Ventra, Massimiliano

    2007-03-01

    Transport in nanoscale systems is usually described as an open-boundary scattering problem. This picture, however, says nothing about the dynamical onset of steady states, their microscopic nature, or their dependence on initial conditions [1]. In order to address these issues, I will first describe the dynamical many-particle state via an effective quantum hydrodynamic theory [2]. This approach allows us to predict a series of novel phenomena like turbulence of the electron liquid [2], local electron heating in nanostructures [3], and the effect of electron viscosity on resistance [4]. I will provide both analytical results and numerical examples of first-principles electron dynamics in nanostructures using the above approach. I will also discuss possible experimental tests of our predictions. Work supported in part by NSF and DOE. [1] N. Bushong, N. Sai and M. Di Ventra, ``Approach to steady-state transport in nanoscale systems'' Nano Letters, 5 2569 (2005); M. Di Ventra and T.N. Todorov, ``Transport in nanoscale systems: the microcanonical versus grand-canonical picture,'' J. Phys. Cond. Matt. 16, 8025 (2004). [2] R. D'Agosta and M. Di Ventra, ``Hydrodynamic approach to transport and turbulence in nanoscale conductors,'' cond-mat/05123326; J. Phys. Cond. Matt., in press. [3] R. D'Agosta, N. Sai and M. Di Ventra, ``Local electron heating in nanoscale conductors,'' cond-mat/0605312; Nano Letters, in press. [4] N. Sai, M. Zwolak, G. Vignale and M. Di Ventra, ``Dynamical corrections to the DFT-LDA electron conductance in nanoscale systems,'' Phys. Rev. Lett. 94, 186810 (2005).

  17. Ultrafast electron transport in graphene and magnetic nanostructures

    NASA Astrophysics Data System (ADS)

    Turchinovich, Dmitry

    2016-03-01

    Ultrafast terahertz spectroscopy is an ideal tool for observation of dynamics of charge, lattice and spin in solids on the most elementary timescale: in the regime ωτ ~ 1, where ω is the electromagnetic wave oscillation frequency, and τ is the characteristic timescale at which the fundamental phenomena in the three subsystems comprising the solid occur. In this paper two case studies will be discussed. (i) Ultrafast electron transport in graphene. We will show, that the free-carrier conductivity of graphene in arbitrary ultrafast, (sub-)picosecond electric fields is defined by the thermodynamic balance maintained within the electronic structure of graphene acting as thermalized electron gas. Within this simple thermodynamic picture, the electron gas quasi-instantaneously increases its temperature by absorbing the energy of driving ultrafast electric field, and at the same time cools down via a time-retarded, few picosecond-long process of phonon emission. The asymmetry in electron heating and cooling dynamics leads to heat accumulation in the electron population of graphene, concomitantly lowering the chemical potential for hotter electrons, and thereby reducing the intraband conductivity of graphene - an effect crucially important for understanding of ultrafast graphene transistors and photodetectors. (ii) We will also discuss the fundamental observation of spin-controlled electron conduction of Fermilevel electrons in ferromagnetic metals, and will directly quantify the Mott picture of conduction in ferromagnets - the effect directly employed in modern magnetic sensor technologies such as giant magnetoresistance.

  18. General theory of electronic transport in molecular crystals. I. Local linear electron-phonon coupling

    NASA Astrophysics Data System (ADS)

    Silbey, R.; Munn, R. W.

    1980-02-01

    An improved general theory of electronic transport in molecular crystals with local linear electron-phonon coupling is presented. It is valid for arbitrary electronic and phonon bandwidths and for arbitrary electron-phonon coupling strength, yielding small-polaron theory for narrow electronic bands and strong coupling, and semiconductor theory for wide electronic bands and weak coupling. Detailed results are derived for electronic excitations fully clothed with phonons and having a bandwidth no larger than the phonon frequency; the electronic and phonon densities of states are taken as Gaussian for simplicity. The dependence of the diffusion coefficient on temperature and on the other parameters is analyzed thoroughly. The calculated behavior provides a rational interpretation of observed trends in the magnitude and temperature dependence of charge-carrier drift mobilities in molecular crystals.

  19. Electron transport and photophosphorylation by Photosystem I in vivo in plants and cyanobacteria.

    PubMed

    Fork, D C; Herbert, S K

    1993-06-01

    Recently, a number of techniques, some of them relatively new and many often used in combination, have given a clearer picture of the dynamic role of electron transport in Photosystem I of photosynthesis and of coupled cyclic photophosphorylation. For example, the photoacoustic technique has detected cyclic electron transport in vivo in all the major algal groups and in leaves of higher plants. Spectroscopic measurements of the Photosystem I reaction center and of the changes in light scattering associated with thylakoid membrane energization also indicate that cyclic photophosphorylation occurs in living plants and cyanobacteria, particularly under stressful conditions.In cyanobacteria, the path of cyclic electron transport has recently been proposed to include an NAD(P)H dehydrogenase, a complex that may also participate in respiratory electron transport. Photosynthesis and respiration may share common electron carriers in eukaryotes also. Chlororespiration, the uptake of O2 in the dark by chloroplasts, is inhibited by excitation of Photosystem I, which diverts electrons away from the chlororespiratory chain into the photosynthetic electron transport chain. Chlororespiration in N-starved Chlamydomonas increases ten fold over that of the control, perhaps because carbohydrates and NAD(P)H are oxidized and ATP produced by this process.The regulation of energy distribution to the photosystems and of cyclic and non-cyclic phosphorylation via state 1 to state 2 transitions may involve the cytochrome b 6-f complex. An increased demand for ATP lowers the transthylakoid pH gradient, activates the b 6-f complex, stimulates phosphorylation of the light-harvesting chlorophyll-protein complex of Photosystem II and decreases energy input to Photosystem II upon induction of state 2. The resulting increase in the absorption by Photosystem I favors cyclic electron flow and ATP production over linear electron flow to NADP and 'poises' the system by slowing down the flow of

  20. First-principles calculation of electronic structure and optical absorption of BN ZnO

    NASA Astrophysics Data System (ADS)

    Zhang, Xiao; Schleife, Andre

    2015-03-01

    The α-BN structure of ZnO, a nonequilibrium phase with a transition pressure of 25 GPa, has been found in nano structures of ZnO. The structural difference between the BN structure and the equilibrium wurtzite structure can play an important role for applications of nanostructured ZnO. In order to understand the difference, first principles calculations have been performed on both phases. The electronic structure is computed using the GW method based on Density Functional Theory and HSE hybrid functional calculations. The GW method includes the quasiparticle effects due to the screened electron-electron interaction which gives an accurate description of the electronic band structure and density of states. After that, by solving the Bethe-Salpeter Equation for the optical polarization function, which take excitonic effects into account, we have achieved an accurate description of optical absorption spectra for both structures. We find a good agreement with experimental and previous computational results for WZ structure, and predict the absorption for the BN structure. The BN structure shows a larger band gap and we found a very large optical anisotropy: The gap for extraordinary light polarization is almost 0.7eV larger than that for ordinary light polarization.

  1. Suppression of infrared absorption in nanostructured metals by controlling Faraday inductance and electron path length.

    PubMed

    Han, Sang Eon

    2016-02-01

    Nanostructured metals have been intensively studied for optical applications over the past few decades. However, the intrinsic loss of metals has limited the optical performance of the metal nanostructures in diverse applications. In particular, light concentration in metals by surface plasmons or other resonances causes substantial absorption in metals. Here, we avoid plasmonic excitations for low loss and investigate methods to further suppress loss in nanostructured metals. We demonstrate that parasitic absorption in metal nanostructures can be significantly reduced over a broad band by increasing the Faraday inductance and the electron path length. For an example structure, the loss is reduced in comparison to flat films by more than an order of magnitude over most of the very broad spectrum between short and long wavelength infrared. For a photodetector structure, the fraction of absorption in the photoactive material increases by two orders of magnitude and the photoresponsivity increases by 15 times because of the selective suppression of metal absorption. These findings could benefit many metal-based applications that require low loss such as photovoltaics, photoconductive detectors, solar selective surfaces, infrared-transparent defrosting windows, and other metamaterials.

  2. LYTIC ACTIVITIES IN RENAL PROTEIN ABSORPTION DROPLETS. AN ELECTRON MICROSCOPICAL CYTOCHEMICAL STUDY.

    PubMed

    MILLER, F; PALADE, G E

    1964-12-01

    The digestive cycle following reabsorption of hemoglobin by cells of the proximal convoluted tubules in mouse kidney and the uptake of ferritin by glomerular mesangial cells in the kidney of normal and nephrotic rats were investigated by electron microscopical histochemical procedures. Mouse kidneys, sampled at closely spaced time points between 1 to 48 hours after intraperitoneal injection of hemoglobin, and rat (normal and nephrotic) kidneys, sampled at 30 minutes, 2 hours, and 48 hours after intravenous injection of ferritin, were fixed in glutaraldehyde, cut at 50 micro on a freezing microtome, incubated for acid phosphatase and thiolacetate-esterase, and postfixed in OsO(4). Satisfactory preservation of fine structure permitted the localization of the enzymatic reaction products on cell structures involved in uptake and digestion of exogenous proteins. The latter were identified either by their density (hemoglobin) or their molecular structure (ferritin). It was found that lysosomal enzymic activities and incorporated exogenous proteins occur together in the same membrane-bounded structures. In the cells of the proximal convolution, lytic activities become demonstrable within 1 hour after hemoglobin injection, appear first in apical vacuoles filled with hemoglobin, and persist in fully formed protein absorption droplets. At the end of the lytic cycle ( approximately 48 hours post injection), the cells have an increased population of polymorphic bodies which exhibit lytic activities. In smaller numbers, identical bodies occur in controls. It is concluded that they represent remnants of previous digestive events. The means by which the resorptive vacuoles acquire hydrolytic activities remain unknown. Fusion of newly formed vacuoles with residual bodies was not seen, and hemoglobin incorporation into such bodies was only occasionally encountered. Acid phosphatase activity was found sometimes in the Golgi complex, but enzyme transport from the complex to the

  3. Simulation of laser-plasma interactions and fast-electron transport in inhomogeneous plasma

    SciTech Connect

    Cohen, B.I. Kemp, A.J.; Divol, L.

    2010-06-20

    A new framework is introduced for kinetic simulation of laser-plasma interactions in an inhomogeneous plasma motivated by the goal of performing integrated kinetic simulations of fast-ignition laser fusion. The algorithm addresses the propagation and absorption of an intense electromagnetic wave in an ionized plasma leading to the generation and transport of an energetic electron component. The energetic electrons propagate farther into the plasma to much higher densities where Coulomb collisions become important. The high-density plasma supports an energetic electron current, return currents, self-consistent electric fields associated with maintaining quasi-neutrality, and self-consistent magnetic fields due to the currents. Collisions of the electrons and ions are calculated accurately to track the energetic electrons and model their interactions with the background plasma. Up to a density well above critical density, where the laser electromagnetic field is evanescent, Maxwell's equations are solved with a conventional particle-based, finite-difference scheme. In the higher-density plasma, Maxwell's equations are solved using an Ohm's law neglecting the inertia of the background electrons with the option of omitting the displacement current in Ampere's law. Particle equations of motion with binary collisions are solved for all electrons and ions throughout the system using weighted particles to resolve the density gradient efficiently. The algorithm is analyzed and demonstrated in simulation examples. The simulation scheme introduced here achieves significantly improved efficiencies.

  4. Hybrid Simulation of Laser-Plasma Interactions and Fast Electron Transport in Inhomogeneous Plasma

    SciTech Connect

    Cohen, B I; Kemp, A; Divol, L

    2009-05-27

    A new framework is introduced for kinetic simulation of laser-plasma interactions in an inhomogenous plasma motivated by the goal of performing integrated kinetic simulations of fast-ignition laser fusion. The algorithm addresses the propagation and absorption of an intense electromagnetic wave in an ionized plasma leading to the generation and transport of an energetic electron component. The energetic electrons propagate farther into the plasma to much higher densities where Coulomb collisions become important. The high-density plasma supports an energetic electron current, return currents, self-consistent electric fields associated with maintaining quasi-neutrality, and self-consistent magnetic fields due to the currents. Collisions of the electrons and ions are calculated accurately to track the energetic electrons and model their interactions with the background plasma. Up to a density well above critical density, where the laser electromagnetic field is evanescent, Maxwell's equations are solved with a conventional particle-based, finite-difference scheme. In the higher-density plasma, Maxwell's equations are solved using an Ohm's law neglecting the inertia of the background electrons with the option of omitting the displacement current in Ampere's law. Particle equations of motion with binary collisions are solved for all electrons and ions throughout the system using weighted particles to resolve the density gradient efficiently. The algorithm is analyzed and demonstrated in simulation examples. The simulation scheme introduced here achieves significantly improved efficiencies.

  5. The electronic absorption study of imide anion radicals in terms of time dependent density functional theory

    NASA Astrophysics Data System (ADS)

    Andrzejak, Marcin; Sterzel, Mariusz; Pawlikowski, Marek T.

    2005-07-01

    The absorption spectra of the N-(2,5-di- tert-butylphenyl) phthalimide ( 1-), N-(2,5-di- tert-butylphenyl)-1,8-naphthalimide ( 2-) and N-(2,5-di- tert-butylphenyl)-perylene-3,4-dicarboximide ( 3-) anion radicals are studied in terms of time dependent density functional theory (TDDFT). For these anion radicals a large number electronic states (from 30 to 60) was found in the visible and near-IR regions (5000-45000 cm -1). In these regions the TD/B3LYP treatment at the 6-1+G* level is shown to reproduce satisfactorily the empirical absorption spectra of all three anion radicals studied. The most apparent discrepancies between purely electronic theory and the experiment could be found in the excitation region corresponding to D0→ D1 transitions in the 2- and 3- molecules. For these species we argue that the structures seen in the lowest energy part of the absorptions of the 2- and 3- species are very likely due to Franck-Condon (FC) activity of the totally symmetric vibrations not studied in this Letter.

  6. Laser absorption and third-harmonic generation in free-electron nanofilms

    SciTech Connect

    Fomichev, Sergey V.; Zaretsky, David F.; Becker, Wilhelm

    2009-02-15

    The collective collisionless dynamics of the electron gas in free-electron nanofilms irradiated by an obliquely incident p-polarized laser wave are considered in the classical hydrodynamic and jellium-model approximations. The two cases of cold metallic nanofilms and hot free-electron nanofilms laser ionized and laser heated by a pump-laser prepulse are investigated with proper electron statistics. Both linear and nonlinear properties of the plasma resonance excitation in the nanofilms are studied in detail for different film parameters (film thickness, thickness of the diffuse film boundary, outer-ionization degree for hot laser-ionized/heated films, etc.). The significant role of the diffuse film boundaries for both linear absorption of the laser field and third-harmonic generation is demonstrated. For this goal, we do not use the standard dielectric-permittivity approach with boundary conditions between two different media but solve continuously over all space the full set of hydrodynamic and electrodynamic equations in nonrelativistic one-dimensional approximation. It is shown that collisionless edge absorption may be dominant in thin nanofilms, while in cold metal nanofilms it results in the appearance of several linear-absorption resonances below the bulk-plasma resonance frequency. For hot nanofilms, drastic broadening of the linear-plasma-resonance profile is obtained in calculations when the film thickness is reduced. In our model, the third-harmonic generation is determined by the density gradient in the diffuse film edges. Additional resonances in third-harmonic generation as a function of laser frequency are obtained for cold metal nanofilms. They differ from the standard third-order nonlinear resonance, which is located at one third of the plasma resonance frequency. The important role of the outer-ionization degree in forming the third-order nonlinear response of the hot laser-ionized film is also analyzed and discussed.

  7. Electronic transport in benzodifuran single-molecule transistors

    NASA Astrophysics Data System (ADS)

    Xiang, An; Li, Hui; Chen, Songjie; Liu, Shi-Xia; Decurtins, Silvio; Bai, Meilin; Hou, Shimin; Liao, Jianhui

    2015-04-01

    Benzodifuran (BDF) single-molecule transistors have been fabricated in electromigration break junctions for electronic measurements. The inelastic electron tunneling spectrum validates that the BDF molecule is the pathway of charge transport. The gating effect is analyzed in the framework of a single-level tunneling model combined with transition voltage spectroscopy (TVS). The analysis reveals that the highest occupied molecular orbital (HOMO) of the thiol-terminated BDF molecule dominates the charge transport through Au-BDF-Au junctions. Moreover, the energy shift of the HOMO caused by the gate voltage is the main reason for conductance modulation. In contrast, the electronic coupling between the BDF molecule and the gold electrodes, which significantly affects the low-bias junction conductance, is only influenced slightly by the applied gate voltage. These findings will help in the design of future molecular electronic devices.Benzodifuran (BDF) single-molecule transistors have been fabricated in electromigration break junctions for electronic measurements. The inelastic electron tunneling spectrum validates that the BDF molecule is the pathway of charge transport. The gating effect is analyzed in the framework of a single-level tunneling model combined with transition voltage spectroscopy (TVS). The analysis reveals that the highest occupied molecular orbital (HOMO) of the thiol-terminated BDF molecule dominates the charge transport through Au-BDF-Au junctions. Moreover, the energy shift of the HOMO caused by the gate voltage is the main reason for conductance modulation. In contrast, the electronic coupling between the BDF molecule and the gold electrodes, which significantly affects the low-bias junction conductance, is only influenced slightly by the applied gate voltage. These findings will help in the design of future molecular electronic devices. Electronic supplementary information (ESI) available: The fabrication procedure for BDF single

  8. Transport of the plasma sheet electrons to the geostationary distances

    NASA Astrophysics Data System (ADS)

    Ganushkina, N. Y.; Amariutei, O. A.; Shprits, Y. Y.; Liemohn, M. W.

    2013-01-01

    Abstract<p label="1">The <span class="hlt">transport</span> and acceleration of low-energy <span class="hlt">electrons</span> (50-250 keV) from the plasma sheet to the geostationary orbit were investigated. Two moderate storm events, which occurred on 6-7 November 1997 and 12-14 June 2005, were modeled using the Inner Magnetosphere Particle <span class="hlt">Transport</span> and Acceleration model (IMPTAM) with the boundary set at 10 RE in the plasma sheet. The output of the IMPTAM was compared to the observed <span class="hlt">electron</span> fluxes in four energy ranges (50-225 keV) measured by the Synchronous Orbit Particle Analyzer instrument onboard the Los Alamos National Laboratory spacecraft. It was found that the large-scale convection in combination with substorm-associated impulsive fields is the drivers of the <span class="hlt">transport</span> of plasma sheet <span class="hlt">electrons</span> from 10 RE to geostationary orbit at 6.6 RE during storm times. The addition of radial diffusion had no significant influence on the modeled <span class="hlt">electron</span> fluxes. At the same time, the modeled <span class="hlt">electron</span> fluxes are one (two) order(s) smaller than the observed ones for 50-150 keV (150-225 keV) <span class="hlt">electrons</span>, respectively, most likely due to inaccuracy of <span class="hlt">electron</span> boundary conditions. The loss processes due to wave-particle interactions were not considered. The choice of the large-scale convection electric field model used in simulations did not have a significant influence on the modeled <span class="hlt">electron</span> fluxes, since there is not much difference between the equipotential contours given by the Volland-Stern and the Boyle et al. (1997) models at distances from 10 to 6.6 RE in the plasma sheet. Using the TS05 model for the background magnetic field instead of the T96 model resulted in larger deviations of the modeled <span class="hlt">electron</span> fluxes from the observed ones due to specific features of the TS05 model. The increase in the modeled <span class="hlt">electron</span> fluxes can be as large as two orders of magnitude when substorm-associated electromagnetic fields were taken into account. The obtained model distribution of low-energy <span class="hlt">electron</span></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFMSM44A..08G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFMSM44A..08G"><span id="translatedtitle"><span class="hlt">Transport</span> of the plasma sheet <span class="hlt">electrons</span> to the geostationary distances</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ganushkina, N. Y.; Amariutei, O. A.; Shprits, Y.; Liemohn, M. W.</p> <p>2012-12-01</p> <p>The <span class="hlt">transport</span> and acceleration of low energy <span class="hlt">electrons</span> (10-250 keV) from the plasma sheet to the geostationary orbit were investigated. Two moderate storm events, which occurred on November 6-7, 1997 and June 12-14, 2005, were modeled using the Inner Magnetosphere Particle <span class="hlt">Transport</span> and Acceleration model (IMPTAM) with the boundary set at 10 RE in the plasma sheet. The output of the IMPTAM model was compared to the observed <span class="hlt">electron</span> fluxes in four energy ranges measured onboard the LANL spacecraft by the SOPA instrument. It was found that the large-scale convection in combination with substorm-associated impulsive fields are the drivers of the <span class="hlt">transport</span> of plasma sheet <span class="hlt">electrons</span> from 10 RE to geostationary orbit at 6.6 RE during storm times. The addition of radial diffusion had no significant influence on the modeled <span class="hlt">electron</span> fluxes. At the same time, comparison between the modeled <span class="hlt">electron</span> fluxes and observed ones showed two orders of difference most likely due to inaccuracy of <span class="hlt">electron</span> boundary conditions and omission of the important loss processes due to wave-particle interactions. This did not allow us to accuractly reproduce the dynamics of 150-225 keV <span class="hlt">electron</span> fluxes. The choice of the large-scale convection electric field model used in simulations did not significantly influence on the modeled <span class="hlt">electron</span> fluxes, since there is not much difference between the equipotential contours given by the Volland-Stern and Boyle et al. [1997] models at the distances from 10 to 6.6 RE in the plasma sheet. Using the TS05 model for the background magnetic field instead of the T96 model resulted in larger deviations of the modeled <span class="hlt">electron</span> fluxes from the observed ones due to specific features of the TS05 model. The increase in the modeled <span class="hlt">electron</span> fluxes can be as large as three orders of magnitude when substorm-associated electromagnetic fields were taken into account. The obtained model distribution of low energy <span class="hlt">electron</span> fluxes can be used as an input to the radiation</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/18371296','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/18371296"><span id="translatedtitle">Feedback regulation of photosynthetic <span class="hlt">electron</span> <span class="hlt">transport</span> by NADP(H) redox poise.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hald, Simon; Nandha, Beena; Gallois, Patrick; Johnson, Giles N</p> <p>2008-05-01</p> <p>When plants experience an imbalance between the <span class="hlt">absorption</span> of light energy and the use of that energy to drive metabolism, they are liable to suffer from oxidative stress. Such imbalances arise due to environmental conditions (e.g. heat, chilling or drought), and can result in the production of reactive oxygen species (ROS). Here, we present evidence for a novel protective process - feedback redox regulation via the redox poise of the NADP(H) pool. Photosynthetic <span class="hlt">electron</span> <span class="hlt">transport</span> was studied in two transgenic tobacco (Nicotiana tabacum) lines - one having reduced levels of ferredoxin NADP+-reductase (FNR), the enzyme responsible for reducing NADP+, and the other reduced levels of glyceraldehyde 3-phosphate dehydrogenase (GAPDH), the principal consumer of NADPH. Both had a similar degree of inhibition of carbon fixation and impaired <span class="hlt">electron</span> <span class="hlt">transport</span>. However, whilst FNR antisense plants were obviously stressed, with extensive bleaching of leaves, GAPDH antisense plants showed no visible signs of stress, beyond having a slowed growth rate. Examination of <span class="hlt">electron</span> <span class="hlt">transport</span> in these plants indicated that this difference is due to feedback regulation occurring in the GAPDH but not the FNR antisense plants. We propose that this reflects the occurrence of a previously undescribed regulatory pathway responding to the redox poise of the NADP(H) pool.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015APS..SHK.W1015F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015APS..SHK.W1015F"><span id="translatedtitle">Pressure dependence of Hexanitrostilbene Raman/ <span class="hlt">electronic</span> <span class="hlt">absorption</span> spectra to validate DFT EOS</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Farrow, Darcie; Alam, Kathleen; Martin, Laura; Fan, Hongyou; Kay, Jeffrey; Wixom, Ryan</p> <p>2015-06-01</p> <p>Due to its thermal stability and low vapor pressure, Hexanitrostilbene (HNS) is often used in high-temperature or vacuum applications as a detonator explosive or in mild detonating fuse. Toward improving the accuracy of the equation of state used in hydrodynamic simulations of the performance of HNS, we have measured the Raman and <span class="hlt">electronic</span> <span class="hlt">absorption</span> spectra of this material under static pressure in a diamond anvil cell. Density functional theory calculations were used to simulate the pressure dependence of the Raman/<span class="hlt">Electronic</span> spectra along the Hugoniot and 300K isotherm for comparison and to aid in interpreting the data. We will discuss changes in the <span class="hlt">electronic</span> structure of HNS under pressure, validation of a DFT predicted equation of state (EOS), and using this data as a basis for understanding future pulsed Raman measurements on dynamically compressed HNS samples.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1096488','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1096488"><span id="translatedtitle">LDRD project 151362 : low energy <span class="hlt">electron</span>-photon <span class="hlt">transport</span>.</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Kensek, Ronald Patrick; Hjalmarson, Harold Paul; Magyar, Rudolph J.; Bondi, Robert James; Crawford, Martin James</p> <p>2013-09-01</p> <p>At sufficiently high energies, the wavelengths of <span class="hlt">electrons</span> and photons are short enough to only interact with one atom at time, leading to the popular %E2%80%9Cindependent-atom approximation%E2%80%9D. We attempted to incorporate atomic structure in the generation of cross sections (which embody the modeled physics) to improve <span class="hlt">transport</span> at lower energies. We document our successes and failures. This was a three-year LDRD project. The core team consisted of a radiation-<span class="hlt">transport</span> expert, a solid-state physicist, and two DFT experts.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.B54D..01N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.B54D..01N"><span id="translatedtitle">Extracellular <span class="hlt">Electron</span> <span class="hlt">Transport</span> (EET): Metal Cycling in Extreme Places</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nealson, K. H.</p> <p>2014-12-01</p> <p>Extracellular <span class="hlt">electron</span> <span class="hlt">transport</span>, or EET, is the process whereby bacteria either donate <span class="hlt">electrons</span> to an <span class="hlt">electron</span> acceptor (usually insoluble), or take up <span class="hlt">electrons</span> from and <span class="hlt">electron</span> donor (usually insoluble) that is located outside the cell. Iron cycling is inherently linked to EET, as both reduced iron (<span class="hlt">electron</span> donors), and oxidized iron (<span class="hlt">electron</span> acceptors) can be found as insoluble minerals, and require specialized molecular machines to accomplish these extracellular geobiological reactions. Bacteria in the group Shewanella are able to catalyze EET in both directions, and are involved with a number of different iron conversions, but are not good role models for extreme conditions - to our knowledge there are no shewanellae that are tolerant to extremes of temperature or pH, the two usual. This being said, when cells are energy starved via limitation for <span class="hlt">electron</span> acceptors, they respond by turning on the system(s) for EET. Thus, in this presentation the known mechanism(s) of EET will be discussed, along with recent findings and reports of EET-capable organisms from a variety of extreme environments. From these data, I put forward the hypothesis that there are many microbes (many of them from extreme environments) that will be resistant to cultivation by "standard microbiological methods", yet lend themselves well to cultivation via electrochemical methods.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016TDM.....3b5018G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016TDM.....3b5018G"><span id="translatedtitle">Effect of compression on the <span class="hlt">electronic</span>, optical and <span class="hlt">transport</span> properties of MoS2/graphene-based junctions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ghorbani-Asl, Mahdi; Bristowe, Paul D.; Koziol, K.; Heine, Thomas; Kuc, Agnieszka</p> <p>2016-06-01</p> <p><span class="hlt">Electronic</span>, optical and <span class="hlt">transport</span> properties of the MoS2/graphene heterostructure have been investigated as function of applied uniaxial compression normal to the interface plane using first principles calculations and a non-equilibrium Green’s function approach. The results show that a small compressive load (∼1 GPa) can open up the band gap (∼12 meV), reduce the optical <span class="hlt">absorption</span> coefficient (∼7%), redshift the <span class="hlt">absorption</span> spectrum, and create non-Ohmic I –V characteristics that depend on the magnitude of applied bias. This suggests that graphene/MoS2 heterostructure can be suitable for electromechanical and photomechanical devices where the <span class="hlt">electronic</span>, optical and <span class="hlt">transport</span> properties can be tuned by an appropriate application of bias and mechanical deformations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AcSpA..94..256M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AcSpA..94..256M"><span id="translatedtitle">Solvatochromic behavior of the <span class="hlt">electronic</span> <span class="hlt">absorption</span> spectra of gallic acid and some of its azo derivatives</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Masoud, Mamdouh S.; Hagagg, Sawsan S.; Ali, Alaa E.; Nasr, Nessma M.</p> <p></p> <p>The <span class="hlt">electronic</span> <span class="hlt">absorption</span> spectra of gallic acid and its azo derivatives have been studied in various solvents of different polarities. Multiple regression techniques were applied to calculate the regression and correlation coefficients based on an equation that relates the wavenumbers of the <span class="hlt">absorption</span> band maxima (υmax-) to the solvent parameters; refractive index (n), dielectric constant (D), empirical Kamlet-Taft solvent parameters, π*(dipolarity/polarizability), α (solvent hydrogen-bond donor acidity) and β (solvent hydrogen-bond acceptor basicity). The fitting coefficient obtained from this analysis allows estimating the contribution of each type of interactions relative to total spectral shifts in solution. The dependence of υmax- on the solvent parameters indicates that the obtained bands are affected by specific and non-specific solute-solvent interactions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22516126','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22516126"><span id="translatedtitle">Solvatochromic behavior of the <span class="hlt">electronic</span> <span class="hlt">absorption</span> spectra of gallic acid and some of its azo derivatives.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Masoud, Mamdouh S; Hagagg, Sawsan S; Ali, Alaa E; Nasr, Nessma M</p> <p>2012-08-01</p> <p>The <span class="hlt">electronic</span> <span class="hlt">absorption</span> spectra of gallic acid and its azo derivatives have been studied in various solvents of different polarities. Multiple regression techniques were applied to calculate the regression and correlation coefficients based on an equation that relates the wavenumbers of the <span class="hlt">absorption</span> band maxima (υ(max)(-)) to the solvent parameters; refractive index (n), dielectric constant (D), empirical Kamlet-Taft solvent parameters, π*(dipolarity/polarizability), α (solvent hydrogen-bond donor acidity) and β (solvent hydrogen-bond acceptor basicity). The fitting coefficient obtained from this analysis allows estimating the contribution of each type of interactions relative to total spectral shifts in solution. The dependence of υ(max)(-) on the solvent parameters indicates that the obtained bands are affected by specific and non-specific solute-solvent interactions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/25495044','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/25495044"><span id="translatedtitle"><span class="hlt">Electronic</span> <span class="hlt">absorption</span> spectra of H₂C₆O⁺ isomers: produced by ion-molecule reactions.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Chakraborty, Arghya; Fulara, Jan; Maier, John P</p> <p>2015-01-01</p> <p>Three <span class="hlt">absorption</span> systems with origins at 354, 497, and 528 nm were detected after mass-selected deposition of H2C6O(+) in a 6 K neon matrix. The ions were formed by the reaction of C2O with HC4H(+) in a mixture of C3O2 and diacetylene in a hot cathode source, or by dissociative ionization of tetrabromocyclohexadienone. The 497 and 354 nm systems are assigned to the 1(2)A″ ← X(2)A″ and 2(2)A″ ← X(2)A″ <span class="hlt">electronic</span> transitions of B(+), (2-ethynylcycloallyl)methanone cation, and the 528 nm <span class="hlt">absorption</span> to the 1(2)A2 ← X(2)B1 transition of F(+), 2-ethynylbut-3-yn-1-enone-1-ylide, on the basis of calculated excitation energies with CASPT2. PMID:25495044</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/22107398','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/22107398"><span id="translatedtitle"><span class="hlt">Electronic</span> structure investigation of highly compressed aluminum with K edge <span class="hlt">absorption</span> spectroscopy.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Benuzzi-Mounaix, A; Dorchies, F; Recoules, V; Festa, F; Peyrusse, O; Levy, A; Ravasio, A; Hall, T; Koenig, M; Amadou, N; Brambrink, E; Mazevet, S</p> <p>2011-10-14</p> <p>The <span class="hlt">electronic</span> structure evolution of highly compressed aluminum has been investigated using time resolved K edge x-ray <span class="hlt">absorption</span> spectroscopy. A long laser pulse (500 ps, I(L)≈8×10(13) W/cm(2)) was used to create a uniform shock. A second ps pulse (I(L)≈10(17)  W/cm(2)) generated an ultrashort broadband x-ray source near the Al K edge. The main target was designed to probe aluminum at reshocked conditions up to now unexplored (3 times the solid density and temperatures around 8 eV). The hydrodynamical conditions were obtained using rear side visible diagnostics. Data were compared to ab initio and dense plasma calculations, indicating potential improvements in either description. This comparison shows that x-ray-<span class="hlt">absorption</span> near-edge structure measurements provide a unique capability to probe matter at these extreme conditions and severally constrains theoretical approaches currently used. PMID:22107398</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016Nanot..27m5302S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016Nanot..27m5302S"><span id="translatedtitle">Geometric effects in the <span class="hlt">electronic</span> <span class="hlt">transport</span> of deformed nanotubes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Santos, Fernando; Fumeron, Sébastien; Berche, Bertrand; Moraes, Fernando</p> <p>2016-04-01</p> <p>Quasi-two-dimensional systems may exibit curvature, which adds three-dimensional influence to their internal properties. As shown by da Costa (1981 Phys. Rev. A 23 1982-7), charged particles moving on a curved surface experience a curvature-dependent potential which greatly influence their dynamics. In this paper, we study the <span class="hlt">electronic</span> ballistic <span class="hlt">transport</span> in deformed nanotubes. The one-<span class="hlt">electron</span> Schrödinger equation with open boundary conditions is solved numerically with a flexible MAPLE code made available as supplementary data. We find that the curvature of the deformations indeed has strong effects on the <span class="hlt">electron</span> dynamics, suggesting its use in the design of nanotube-based <span class="hlt">electronic</span> devices.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/22051363','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22051363"><span id="translatedtitle">Spatially resolved study of primary <span class="hlt">electron</span> <span class="hlt">transport</span> in magnetic cusps</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Hubble, Aimee A.; Foster, John E.</p> <p>2012-01-15</p> <p>Spatially resolved primary <span class="hlt">electron</span> current density profiles were measured using a planar Langmuir probe in the region above a magnetic cusp in a small ion thruster discharge chamber. The probe current maps obtained were used to study the <span class="hlt">electron</span> collection mechanics in the cusp region in the limit of zero gas flow and no plasma production, and they allowed for the visualization of primary <span class="hlt">electron</span> <span class="hlt">transport</span> through the cusp. Attenuation coefficients and loss widths were calculated as a function of probe distance above the anode at various operating conditions. Finally, the collection mechanics between two magnetic cusps were studied and compared. It was found that primary <span class="hlt">electron</span> collection was dominated by the upstream magnet ring.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li class="active"><span>13</span></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_13 --> <div id="page_14" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li class="active"><span>14</span></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="261"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/3847','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/3847"><span id="translatedtitle">The macro response Monte Carlo method for <span class="hlt">electron</span> <span class="hlt">transport</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Svatos, M M</p> <p>1998-09-01</p> <p>The main goal of this thesis was to prove the feasibility of basing <span class="hlt">electron</span> depth dose calculations in a phantom on first-principles single scatter physics, in an amount of time that is equal to or better than current <span class="hlt">electron</span> Monte Carlo methods. The Macro Response Monte Carlo (MRMC) method achieves run times that are on the order of conventional <span class="hlt">electron</span> <span class="hlt">transport</span> methods such as condensed history, with the potential to be much faster. This is possible because MRMC is a Local-to-Global method, meaning the problem is broken down into two separate <span class="hlt">transport</span> calculations. The first stage is a local, in this case, single scatter calculation, which generates probability distribution functions (PDFs) to describe the <span class="hlt">electron</span>'s energy, position and trajectory after leaving the local geometry, a small sphere or "kugel" A number of local kugel calculations were run for calcium and carbon, creating a library of kugel data sets over a range of incident energies (0.25 MeV - 8 MeV) and sizes (0.025 cm to 0.1 cm in radius). The second <span class="hlt">transport</span> stage is a global calculation, where steps that conform to the size of the kugels in the library are taken through the global geometry. For each step, the appropriate PDFs from the MRMC library are sampled to determine the <span class="hlt">electron</span>'s new energy, position and trajectory. The <span class="hlt">electron</span> is immediately advanced to the end of the step and then chooses another kugel to sample, which continues until <span class="hlt">transport</span> is completed. The MRMC global stepping code was benchmarked as a series of subroutines inside of the Peregrine Monte Carlo code. It was compared to Peregrine's class II condensed history <span class="hlt">electron</span> <span class="hlt">transport</span> package, EGS4, and MCNP for depth dose in simple phantoms having density inhomogeneities. Since the kugels completed in the library were of relatively small size, the zoning of the phantoms was scaled down from a clinical size, so that the energy deposition algorithms for spreading dose across 5-10 zones per kugel could be tested. Most</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002AcSpA..58.2013M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002AcSpA..58.2013M"><span id="translatedtitle"><span class="hlt">Electronic</span> structure of some adenosine receptor antagonists. III. Quantitative investigation of the <span class="hlt">electronic</span> <span class="hlt">absorption</span> spectra of alkyl xanthines</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Moustafa, H.; Shalaby, Samia H.; El-sawy, K. M.; Hilal, Rifaat</p> <p>2002-07-01</p> <p>Quantitative and comparative investigation of the <span class="hlt">electronic</span> <span class="hlt">absorption</span> spectra of theophylline, caffeine and their derivatives is reported. The spectra of theophylline, caffeine and theobromine were compared to establish the predominant tautomeric species in solution. This comparison, analysis of solvent effects and assignments of the observed transitions via MO computations indicate the exits of only one tautomeric species in solution that is the N7 form. A low-lying triplet state was identified which corresponds to a HOMO-LUMO transition. This relatively long-lived T 1 state is always less polar than the ground state and may very well underlie the photochemical reactivity of alkyl xanthines. Substituents of different <span class="hlt">electron</span> donating or withdrawing strengths and solvent effects are investigated and analyzed. The present analysis is facilitated via computer deconvolution of the observed spectra and MO computation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/503467','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/503467"><span id="translatedtitle">Fabrication and <span class="hlt">electronic</span> <span class="hlt">transport</span> studies of single nanocrystal systems</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Klein, D L</p> <p>1997-05-01</p> <p>Semiconductor and metallic nanocrystals exhibit interesting <span class="hlt">electronic</span> <span class="hlt">transport</span> behavior as a result of electrostatic and quantum mechanical confinement effects. These effects can be studied to learn about the nature of <span class="hlt">electronic</span> states in these systems. This thesis describes several techniques for the <span class="hlt">electronic</span> study of nanocrystals. The primary focus is the development of novel methods to attach leads to prefabricated nanocrystals. This is because, while nanocrystals can be readily synthesized from a variety of materials with excellent size control, means to make electrical contact to these nanocrystals are limited. The first approach that will be described uses scanning probe microscopy to first image and then electrically probe surfaces. It is found that <span class="hlt">electronic</span> investigations of nanocrystals by this technique are complicated by tip-sample interactions and environmental factors such as salvation and capillary forces. Next, an atomic force microscope technique for the catalytic patterning of the surface of a self assembled monolayer is described. In principle, this nano-fabrication technique can be used to create <span class="hlt">electronic</span> devices which are based upon complex arrangements of nanocrystals. Finally, the fabrication and electrical characterization of a nanocrystal-based single <span class="hlt">electron</span> transistor is presented. This device is fabricated using a hybrid scheme which combines <span class="hlt">electron</span> beam lithography and wet chemistry to bind single nanocrystals in tunneling contact between closely spaced metallic leads. In these devices, both Au and CdSe nanocrystals show Coulomb blockade effects with characteristic energies of several tens of meV. Additional structure is seen the <span class="hlt">transport</span> behavior of CdSe nanocrystals as a result of its <span class="hlt">electronic</span> structure.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008JAP...104e4110M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008JAP...104e4110M"><span id="translatedtitle">The effect of implanting boron on the optical <span class="hlt">absorption</span> and <span class="hlt">electron</span> paramagnetic resonance spectra of silica</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Magruder, R. H.; Stesmans, A.; Weeks, R. A.; Weller, R. A.</p> <p>2008-09-01</p> <p>Silica samples (type III, Corning 7940) were implanted with B using multiple energies to produce a layer ˜600 nm thick in which the concentration of B ranged from 0.034 to 2.04 at. %. Optical <span class="hlt">absorption</span> spectra were measured from 1.8 to 6.5 eV. <span class="hlt">Electron</span> paramagnetic resonance (EPR) measurements were generally made at ˜20.3 and 33 GHz for sample temperatures ranging from 77 to 100 K. Based on the EPR spectra three types of defects, namely, Eγ', the E'-type 73 G split doublet (E73'), and the peroxyradical (POR) were identified. No oxygen-associated hole centers (OHCs) nor specific B-associated paramagnetic defects were detected, not even at the largest B concentration of 2.04 at. %. Unlike previous assignments, there was no correlation between the 4.83 eV optical <span class="hlt">absorption</span> band and the observed PORs. From these results, we infer that in addition to POR, there is at least one additional Si-related state absorbing in the 4.8-4.9 eV range that is likely diamagnetic. The 5.85 eV optical <span class="hlt">absorption</span> band is found to be due to the Eγ' and E73' centers, with, in average, quite similar oscillator strengths inferred as before. Both the optical <span class="hlt">absorption</span> and the <span class="hlt">electron</span> spin resonance data can be satisfactorily explained without the need for specific B-associated defect site (s). As no OHCs are detected by ESR, these do not seem to make a detectable contribution to the optical spectra.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/22218426','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22218426"><span id="translatedtitle">Turbulent <span class="hlt">electron</span> <span class="hlt">transport</span> in edge pedestal by <span class="hlt">electron</span> temperature gradient turbulence</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Singh, R.; Jhang, Hogun; Diamond, P. H.</p> <p>2013-11-15</p> <p>We present a model for turbulent <span class="hlt">electron</span> thermal <span class="hlt">transport</span> at the edge pedestal in high (H)-mode plasmas based on <span class="hlt">electron</span> temperature gradient (ETG) turbulence. A quasi-linear analysis of electrostatic toroidal ETG modes shows that both turbulent <span class="hlt">electron</span> thermal diffusivity and hyper-resistivity exhibits the Ohkawa scaling in which the radial correlation length of turbulence becomes the order of <span class="hlt">electron</span> skin depth. Combination of the Ohkawa scales and the plasma current dependence results in a novel confinement scaling inside the pedestal region. It is also shown that ETG turbulence induces a thermoelectric pinch, which may accelerate the density pedestal formation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26368966','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26368966"><span id="translatedtitle">Enhancing light <span class="hlt">absorption</span> within the carrier <span class="hlt">transport</span> length in quantum junction solar cells.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Fu, Yulan; Hara, Yukihiro; Miller, Christopher W; Lopez, Rene</p> <p>2015-09-10</p> <p>Colloidal quantum dot (CQD) solar cells have attracted tremendous attention because of their tunable <span class="hlt">absorption</span> 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 <span class="hlt">absorption</span> within the carrier <span class="hlt">transport</span> 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/cm<sup>2</sup>, 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. PMID:26368966</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26368966','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26368966"><span id="translatedtitle">Enhancing light <span class="hlt">absorption</span> within the carrier <span class="hlt">transport</span> length in quantum junction solar cells.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Fu, Yulan; Hara, Yukihiro; Miller, Christopher W; Lopez, Rene</p> <p>2015-09-10</p> <p>Colloidal quantum dot (CQD) solar cells have attracted tremendous attention because of their tunable <span class="hlt">absorption</span> 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 <span class="hlt">absorption</span> within the carrier <span class="hlt">transport</span> 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/cm<sup>2</sup>, 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010cosp...38.2989R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010cosp...38.2989R"><span id="translatedtitle">Solar flare accelerated <span class="hlt">electron</span> <span class="hlt">transport</span> through the turbulent solar wind</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Reid, Hamish; Kontar, Eduard</p> <p></p> <p>Solar flare accelerated <span class="hlt">electron</span> beams can become unstable during <span class="hlt">transport</span> from the Sun to the Earth, producing plasma waves in the turbulent inner heliosphere. We simulate solar <span class="hlt">electron</span> beam propagation to the Earth in the weak turbulent regime taking into account the self-consistent generation of plasma waves. Induced plasma waves interact with the density fluctuations from low frequency MHD turbulence present in the background plasma. These fluctuations act to suppress the generation of waves, most acutely when fluctuations have large amplitudes or small wavelengths. The reduction of plasma wave generation alters the wave distribution which changes <span class="hlt">electron</span> beam <span class="hlt">transport</span>. Assuming an observed 5/3 Kolmogorov-type power density spectra of fluctuations, we investigate the energy spectra of the <span class="hlt">electron</span> beam near the Earth. We find the presence of turbulence in the background plasma alters the spectral index below the break energy of the double power-law formed at 1AU. From an initial single power-law <span class="hlt">electron</span> distribution, we find a range of spectra below the break energy, with higher levels of turbulence corresponding to a higher spectral index.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/20860240','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/20860240"><span id="translatedtitle">Nonlocal <span class="hlt">electron</span> <span class="hlt">transport</span> in magnetized plasmas with arbitrary atomic number</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Bennaceur-Doumaz, D.; Bendib, A.</p> <p>2006-09-15</p> <p>The numerical solution of the steady-state <span class="hlt">electron</span> Fokker-Planck equation perturbed with respect to a global equilibrium is presented in magnetized plasmas with arbitrary atomic number Z. The magnetic field is assumed to be constant and the <span class="hlt">electron-electron</span> collisions are described by the Landau collision operator. The solution is derived in the Fourier space and in the framework of the diffusive approximation which captures the spatial nonlocal effects. The <span class="hlt">transport</span> coefficients are deduced and used to close a complete set of nonlocal <span class="hlt">electron</span> fluid equations. This work improves the results of A. Bendib et al. [Phys. Plasmas 9, 1555 (2002)] and of A. V. Brantov et al. [Phys. Plasmas 10, 4633 (2003)] restricted to the local and nonlocal high-Z plasma approximations, respectively. The influence of the magnetic field on the nonlocal effects is discussed. We propose also accurate numerical fits of the relevant <span class="hlt">transport</span> coefficients with respect to the collisionality parameter {lambda}{sub ei}/L and the atomic number Z, where L is the typical scale length and {lambda}{sub ei} is the <span class="hlt">electron</span>-ion mean-free-path.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007APS..MARL31012D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007APS..MARL31012D"><span id="translatedtitle"><span class="hlt">Electron</span> <span class="hlt">Transport</span> and Tunneling in Single Walled Carbon Nanotube Devices</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dirks, Travis; Mason, Nadya</p> <p>2007-03-01</p> <p>Carbon nanotubes remain a fertile ground for the exploration of interacting one-dimensional (1D) physics and Tomonaga-Luttinger liquid theory. Much is still unknown about the factors that influence the <span class="hlt">transport</span> and tunneling properties of interacting 1D systems such as nanotubes. We report on experiments that use techniques such as multiple contacts on long nanotubes and tunable tunnel barriers to determine how the manifestations of <span class="hlt">electron-electron</span> interactions, such as the zero-bias anomaly, depend on the length and defect strength in nanotubes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016ApPhL.108j3502C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016ApPhL.108j3502C"><span id="translatedtitle"><span class="hlt">Transport</span> in organic single-crystal microbelt for conformal <span class="hlt">electronics</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cui, Nan; Tong, Yanhong; Tang, Qingxin; Liu, Yichun</p> <p>2016-03-01</p> <p>We showed the advantages of flexible rubrene organic single-crystal microbelts in high-performance devices and circuits towards conformal <span class="hlt">electronics</span>. The anisotropic <span class="hlt">transport</span> based on the only one organic microbelt was studied by a "cross-channel" method, and the rubrene microbelt showed the highest mobility up to 26 cm2/V s in the length direction. Based on an individual rubrene microbelt, the organic single-crystal circuit with good adherence on a pearl ball and the gain as high as 18 was realized. These results present great potential for applications of organic single-crystal belts in the next-generation conformal <span class="hlt">electronics</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/603471','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/603471"><span id="translatedtitle"><span class="hlt">Electronic</span> structure of barium strontium titanate by soft-x-ray <span class="hlt">absorption</span> spectroscopy</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Uehara, Y.; Underwood, J.H.; Gullikson, E.M.; Perera, R.C.C.</p> <p>1997-04-01</p> <p>Perovskite-type titanates, such as Strontium Titanate (STO), Barium Titanate (BTO), and Lead Titanate (PTO) have been widely studied because they show good electric and optical properties. In recent years, thin films of Barium Strontium Titanate (BST) have been paid much attention as dielectrics of dynamic random access memory (DRAM) capacitors. BST is a better insulator with a higher dielectric constant than STO and can be controlled in a paraelectric phase with an appropriate ratio of Ba/Sr composition, however, few studies have been done on the <span class="hlt">electronic</span> structure of the material. Studies of the <span class="hlt">electronic</span> structure of such materials can be beneficial, both for fundamental physics research and for improving technological applications. BTO is a famous ferroelectric material with a tetragonal structure, in which Ti and Ba atoms are slightly displaced from the lattice points. On the other hand, BST keeps a paraelectric phase, which means that the atoms are still at the cubic lattice points. It should be of great interest to see how this difference of the local structure around Ti atoms between BTO and BST effects the <span class="hlt">electronic</span> structure of these two materials. In this report, the authors present the Ti L{sub 2,3} <span class="hlt">absorption</span> spectra of STO, BTO, and BST measured with very high accuracy in energy of the <span class="hlt">absorption</span> features.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016NatCo...711381B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016NatCo...711381B"><span id="translatedtitle">Nanoscale <span class="hlt">electron</span> <span class="hlt">transport</span> at the surface of a topological insulator</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bauer, Sebastian; Bobisch, Christian A.</p> <p>2016-04-01</p> <p>The use of three-dimensional topological insulators for disruptive technologies critically depends on the dissipationless <span class="hlt">transport</span> of <span class="hlt">electrons</span> at the surface, because of the suppression of backscattering at defects. However, in real devices, defects are unavoidable and scattering at angles other than 180° is allowed for such materials. Until now, this has been studied indirectly by bulk measurements and by the analysis of the local density of states in close vicinity to defect sites. Here, we directly measure the nanoscale voltage drop caused by the scattering at step edges, which occurs if a lateral current flows along a three-dimensional topological insulator. The experiments were performed using scanning tunnelling potentiometry for thin Bi2Se3 films. So far, the observed voltage drops are small because of large contributions of the bulk to the <span class="hlt">electronic</span> <span class="hlt">transport</span>. However, for the use of ideal topological insulating thin films in devices, these contributions would play a significant role.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4844676','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4844676"><span id="translatedtitle">Nanoscale <span class="hlt">electron</span> <span class="hlt">transport</span> at the surface of a topological insulator</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Bauer, Sebastian; Bobisch, Christian A.</p> <p>2016-01-01</p> <p>The use of three-dimensional topological insulators for disruptive technologies critically depends on the dissipationless <span class="hlt">transport</span> of <span class="hlt">electrons</span> at the surface, because of the suppression of backscattering at defects. However, in real devices, defects are unavoidable and scattering at angles other than 180° is allowed for such materials. Until now, this has been studied indirectly by bulk measurements and by the analysis of the local density of states in close vicinity to defect sites. Here, we directly measure the nanoscale voltage drop caused by the scattering at step edges, which occurs if a lateral current flows along a three-dimensional topological insulator. The experiments were performed using scanning tunnelling potentiometry for thin Bi2Se3 films. So far, the observed voltage drops are small because of large contributions of the bulk to the <span class="hlt">electronic</span> <span class="hlt">transport</span>. However, for the use of ideal topological insulating thin films in devices, these contributions would play a significant role. PMID:27098939</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/21537874','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/21537874"><span id="translatedtitle"><span class="hlt">Electron</span> heat <span class="hlt">transport</span> from stochastic fields in gyrokinetic simulations</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Wang, E.; Nevins, W. M.; Candy, J.; Hatch, D.; Terry, P.; Guttenfelder, W.</p> <p>2011-05-15</p> <p>GYRO is used to examine the perturbed magnetic field structure generated by electromagnetic gyrokinetic simulations of the CYCLONE base case as {beta}{sub e} is varied from 0.1% to 0.7%, as investigated by J. Candy [Phys. Plasmas 12, 072307 (2005)]. Poincare surface of section plots obtained from integrating the self-consistent magnetic field demonstrates widespread stochasticity for all nonzero values of {beta}{sub e}. Despite widespread stochasticity of the perturbed magnetic fields, no significant increase in <span class="hlt">electron</span> <span class="hlt">transport</span> is observed. The magnetic diffusion, d{sub m}[A. B. Rechester and M. N. Rosenbluth, Phys. Rev. Lett 40, 38 (1978)], is used to quantify the degree of stochasticity and related to the <span class="hlt">electron</span> heat <span class="hlt">transport</span> for hundreds of time slices in each simulation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/5551451','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/5551451"><span id="translatedtitle">Two-point model for <span class="hlt">electron</span> <span class="hlt">transport</span> in EBT</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Chiu, S.C.; Guest, G.E.</p> <p>1980-01-01</p> <p>The <span class="hlt">electron</span> <span class="hlt">transport</span> in EBT is simulated by a two-point model corresponding to the central plasma and the edge. The central plasma is assumed to obey neoclassical collisionless <span class="hlt">transport</span>. The edge plasma is assumed turbulent and modeled by Bohm diffusion. The steady-state temperatures and densities in both regions are obtained as functions of neutral influx and microwave power. It is found that as the neutral influx decreases and power increases, the edge density decreases while the core density increases. We conclude that if ring instability is responsible for the T-M mode transition, and if stability is correlated with cold <span class="hlt">electron</span> density at the edge, it will depend sensitively on ambient gas pressure and microwave power.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016APS..MARA22005M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016APS..MARA22005M"><span id="translatedtitle">Ab Initio <span class="hlt">Electronic</span> Relaxation Times and <span class="hlt">Transport</span> in Noble Metals</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mustafa, Jamal I.; Bernardi, Marco; Neaton, Jeffrey B.; Louie, Steven G.</p> <p></p> <p>Relaxation times employed to study <span class="hlt">electron</span> <span class="hlt">transport</span> in metals are typically assumed to be constants and obtained empirically using the Drude model. Here, we employ ab initio calculations to compute the <span class="hlt">electron</span>-phonon relaxation times of Cu, Ag, and Au, and find that they vary significantly on the Fermi surface, spanning ~15 -45 fs. We compute room temperature resistivities in excellent agreement with experiment by combining GW bandstructures, Wannier-interpolated band velocities, and ab initio relaxation times. Our calculations are compared to other approximations used for the relaxation times. Additionally, an importance sampling scheme is introduced to speed up the convergence of resistivity and <span class="hlt">transport</span> calculations by sampling directly points on the Fermi surface. This work was supported by NSF Grant No. DMR15-1508412 and U.S. DOE under Contract No. DE-AC02-05CH11231. Computational resources have been provided by DOE at LBNL's NERSC facility.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011PhPl...18e6111W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011PhPl...18e6111W"><span id="translatedtitle"><span class="hlt">Electron</span> heat <span class="hlt">transport</span> from stochastic fields in gyrokinetic simulationsa)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wang, E.; Nevins, W. M.; Candy, J.; Hatch, D.; Terry, P.; Guttenfelder, W.</p> <p>2011-05-01</p> <p>GYRO is used to examine the perturbed magnetic field structure generated by electromagnetic gyrokinetic simulations of the CYCLONE base case as βe is varied from 0.1% to 0.7%, as investigated by J. Candy [Phys. Plasmas 12, 072307 (2005)]. Poincare surface of section plots obtained from integrating the self-consistent magnetic field demonstrates widespread stochasticity for all nonzero values of βe. Despite widespread stochasticity of the perturbed magnetic fields, no significant increase in <span class="hlt">electron</span> <span class="hlt">transport</span> is observed. The magnetic diffusion, dm [A. B. Rechester and M. N. Rosenbluth, Phys. Rev. Lett 40, 38 (1978)], is used to quantify the degree of stochasticity and related to the <span class="hlt">electron</span> heat <span class="hlt">transport</span> for hundreds of time slices in each simulation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26949167','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26949167"><span id="translatedtitle"><span class="hlt">Electron</span> <span class="hlt">transporting</span> organic materials with an exceptional large scale homeotropic molecular orientation.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zhao, Huan; He, Zhiqun; Xu, Min; Liang, Chunjun; Kumar, Sandeep</p> <p>2016-03-28</p> <p>An <span class="hlt">electron</span> <span class="hlt">transporting</span> anthraquinone derivative demonstrated a stable large-scale homeotropic alignment on an open substrate surface, which substantially improved its charge carrier mobility. The <span class="hlt">electron</span> mobility (μ(E)) increased by two orders of magnitude from 3.2 × 10(-4) cm(2) V(-1) s(-1) for the film without alignment to 1.2 × 10(-2) cm(2) V(-1) s(-1) for the homeotropically aligned film. A distinct enhancement in the UV <span class="hlt">absorption</span> spectra of the films around the short wavelength range was observed to be associated with the molecular alignments. These alignments are less sensitive to the substrate under test. The anchoring force of the columnar stacks appears to be related to the nature of the material associated with the strong interaction between the molecules and substrate interface. PMID:26949167</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013JAP...114f3304H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013JAP...114f3304H"><span id="translatedtitle"><span class="hlt">Transport</span> of <span class="hlt">electron</span> beams with initial transverse-longitudinal correlation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Harris, J. R.; Lewellen, J. W.; Poole, B. R.</p> <p>2013-08-01</p> <p>When an <span class="hlt">electron</span> beam whose current varies in time is extracted from a DC gun, the competition between the time-dependent space charge force and the time-independent focusing force will cause a correlation between radius, divergence, current, and position along the beam. This correlation will determine the beam's configuration in trace space, and together with the design of the downstream <span class="hlt">transport</span> system, will determine the quality of the <span class="hlt">transport</span> solutions that can be obtained, including the amplitude of the mismatch oscillations occurring in each slice of the beam. Recent simulations of a simplified diode with Pierce-type focusing operating at nonrelativistic voltages indicated that the radius and divergence of beams extracted from such guns can be approximated to high accuracy as linear functions of current. Here, we consider the impact of this dependence on the beam configuration in trace space and investigate the implications for matching and <span class="hlt">transport</span> of such correlated beams in uniform linear focusing channels.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li class="active"><span>14</span></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_14 --> <div id="page_15" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li class="active"><span>15</span></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="281"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/532581','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/532581"><span id="translatedtitle">Status of <span class="hlt">electron</span> <span class="hlt">transport</span> in MCNP{trademark}</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Hughes, H.G.</p> <p>1997-09-01</p> <p>The latest version of MCNP, the Los Alamos Monte Carlo <span class="hlt">transport</span> code, has now been officially released. MCNP4B has been sent to the Radiation Safety Information Computational Center (RSICC), in Oak Ridge, Tennessee, which is responsible for the further distribution of the code within the US. International distribution of MCNP is done by the Nuclear Energy Agency (ECD/NEA), in Paris, France. Readers with access to the World-Wide-Web should consult the MCNP distribution site http://www-xdiv.lanl.gov/XTM/mcnp/about.html for specific information about contacting RSICC and OECD/NEA. A variety of new features are available in MCNP4B. Among these are differential operator perturbations, cross-section plotting capabilities, enhanced diagnostics for <span class="hlt">transport</span> in repeated structures and lattices, improved efficiency in distributed-memory multiprocessing, corrected particle lifetime and lifespan estimators, and expanded software quality assurance procedures and testing, including testing of the multigroup Boltzmann-Fokker-Planck capability. New and improved cross section sets in the form of ENDF/B-VI evaluations have also been recently released and can be used in MCNP4B. Perhaps most significant for the interests of this special session, the <span class="hlt">electron</span> <span class="hlt">transport</span> algorithm has been improved, especially in the collisional energy-loss straggling and the angular-deflection treatments. In this paper, the author concentrates on a fairly complete documentation of the current status of the <span class="hlt">electron</span> <span class="hlt">transport</span> methods in MCNP.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/22053965','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22053965"><span id="translatedtitle">Note: Measurement of saturable <span class="hlt">absorption</span> by intense vacuum ultraviolet free <span class="hlt">electron</span> laser using fluorescent material</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Inubushi, Y.; Kumagai, T.; Morimoto, S.; Tanaka, T.; Kodama, R.; Yoneda, H.; Higashiya, A.; Ishikawa, T.; Nagasono, M.; Tono, K.; Yabashi, M.; Kimura, H.; Ohashi, H.; Togashi, T.; Sato, F.; Yamaguchi, Y.</p> <p>2010-03-15</p> <p>Advances in free <span class="hlt">electron</span> lasers (FELs) which generate high energy photons are expected to open novel nonlinear optics in the x-ray and vacuum ultraviolet (VUV) regions. In this paper, we report a new method for performing VUV-FEL focusing experiments. A VUV-FEL was focused with Kirkpatrick-Baez optics on a multilayer target, which contains fused silica as a fluorescent material. By measuring the fluorescence, a 5.6x4.9 {mu}m{sup 2} focal spot was observed in situ. Fluorescence was used to measure the saturable <span class="hlt">absorption</span> of VUV pulses in the tin layer. The transmission increases nonlinearly higher with increasing laser intensity.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2010PhDT.......270M&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2010PhDT.......270M&link_type=ABSTRACT"><span id="translatedtitle">Computational study of hot <span class="hlt">electron</span> generation and energy <span class="hlt">transport</span> in intense laser produced hot dense matter</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mishra, Rohini</p> <p></p> <p>Present ultra high power lasers are capable of producing high energy density (HED) plasmas, in controlled way, with a density greater than solid density and at a high temperature of keV (1 keV ˜ 11,000,000° K). Matter in such extreme states is particularly interesting for (HED) physics such as laboratory studies of planetary and stellar astrophysics, laser fusion research, pulsed neutron source etc. To date however, the physics in HED plasma, especially, the energy <span class="hlt">transport</span>, which is crucial to realize applications, has not been understood well. Intense laser produced plasmas are complex systems involving two widely distinct temperature distributions and are difficult to model by a single approach. Both kinetic and collisional process are equally important to understand an entire process of laser-solid interaction. By implementing atomic physics models, such as collision, ionization, and radiation damping, self consistently, in state-of-the-art particle-in-cell code (PICLS) has enabled to explore the physics involved in the HED plasmas. Laser <span class="hlt">absorption</span>, hot <span class="hlt">electron</span> <span class="hlt">transport</span>, and isochoric heating physics in laser produced hot dense plasmas are studied with a help of PICLS simulations. In particular, a novel mode of <span class="hlt">electron</span> acceleration, namely DC-ponderomotive acceleration, is identified in the super intense laser regime which plays an important role in the coupling of laser energy to a dense plasma. Geometric effects on hot <span class="hlt">electron</span> <span class="hlt">transport</span> and target heating processes are examined in the reduced mass target experiments. Further, pertinent to fast ignition, laser accelerated fast <span class="hlt">electron</span> divergence and <span class="hlt">transport</span> in the experiments using warm dense matter (low temperature plasma) is characterized and explained.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/22415564','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22415564"><span id="translatedtitle">The role of <span class="hlt">electron</span>-impact vibrational excitation in <span class="hlt">electron</span> <span class="hlt">transport</span> through gaseous tetrahydrofuran</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Duque, H. V.; Do, T. P. T.; Konovalov, D. A.; White, R. D.; Brunger, M. J. E-mail: darryl.jones@flinders.edu.au; Jones, D. B. E-mail: darryl.jones@flinders.edu.au</p> <p>2015-03-28</p> <p>In this paper, we report newly derived integral cross sections (ICSs) for <span class="hlt">electron</span> impact vibrational excitation of tetrahydrofuran (THF) at intermediate impact energies. These cross sections extend the currently available data from 20 to 50 eV. Further, they indicate that the previously recommended THF ICS set [Garland et al., Phys. Rev. A 88, 062712 (2013)] underestimated the strength of the <span class="hlt">electron</span>-impact vibrational excitation processes. Thus, that recommended vibrational cross section set is revised to address those deficiencies. <span class="hlt">Electron</span> swarm <span class="hlt">transport</span> properties were calculated with the amended vibrational cross section set, to quantify the role of <span class="hlt">electron</span>-driven vibrational excitation in describing the macroscopic swarm phenomena. Here, significant differences of up to 17% in the <span class="hlt">transport</span> coefficients were observed between the calculations performed using the original and revised cross section sets for vibrational excitation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007PhDT.......149T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007PhDT.......149T"><span id="translatedtitle">Charge <span class="hlt">transport</span> and injection in amorphous organic <span class="hlt">electronic</span> materials</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tse, Shing Chi</p> <p></p> <p>This thesis presents how we use various measuring techniques to study the charge <span class="hlt">transport</span> and injection in organic <span class="hlt">electronic</span> materials. Understanding charge <span class="hlt">transport</span> and injection properties in organic solids is of vital importance for improving performance characteristics of organic <span class="hlt">electronic</span> devices, including organic-light-emitting diodes (OLEDs), photovoltaic cells (OPVs), and field effect transistors (OFETs). The charge <span class="hlt">transport</span> properties of amorphous organic materials, commonly used in organic <span class="hlt">electronic</span> devices, are investigated by the means of carrier mobility measurements. Transient electroluminescence (EL) technique was used to evaluate the <span class="hlt">electron</span> mobility of an <span class="hlt">electron</span> <span class="hlt">transporting</span> material--- tris(8-hydroxyquinoline) aluminum (Alq3). The results are in excellent agreement with independent time-of-flight (TOF) measurements. Then, the effect of dopants on <span class="hlt">electron</span> <span class="hlt">transport</span> was also examined. TOF technique was also used to examine the effects of tertiary-butyl (t-Bu) substitutions on anthracene derivatives (ADN). All ADN compounds were found to be ambipolar. As the degree of t-Bu substitution increases, the carrier mobilities decrease progressively. The reduction of carrier mobilities with increasing t-butylation can be attributed to a decrease in the charge-transfer integral or the wavefunction overlap. In addition, from TOF measurements, two naphthylamine-based hole <span class="hlt">transporters</span>, namely, N,N'-diphenyl-N,N'-bis(1-naphthyl)(1,1'-biphenyl)-4,4'diamine (NPB) and 4,4',4"-tris(n-(2-naphthyl)-n-phenyl-amino)-triphenylamine (2TNATA) were found to possess <span class="hlt">electron-transporting</span> (ET) abilities. An organic light-emitting diode that employed NPB as the ET material was demonstrated. The <span class="hlt">electron</span> conducting mechanism of NPB and 2TNATA in relation to the hopping model will be discussed. Furthermore, the ET property of NPB applied in OLEDs will also be examined. Besides transient EL and TOF techniques, we also use dark-injection space-charge-limited current</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/22486307','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22486307"><span id="translatedtitle"><span class="hlt">Electronic</span> <span class="hlt">transport</span> in VO{sub 2}—Experimentally calibrated Boltzmann <span class="hlt">transport</span> modeling</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Kinaci, Alper; Rosenmann, Daniel; Chan, Maria K. Y. E-mail: mchan@anl.gov; Kado, Motohisa; Ling, Chen; Zhu, Gaohua; Banerjee, Debasish E-mail: mchan@anl.gov</p> <p>2015-12-28</p> <p>Materials that undergo metal-insulator transitions (MITs) are under intense study, because the transition is scientifically fascinating and technologically promising for various applications. Among these materials, VO{sub 2} has served as a prototype due to its favorable transition temperature. While the physical underpinnings of the transition have been heavily investigated experimentally and computationally, quantitative modeling of <span class="hlt">electronic</span> <span class="hlt">transport</span> in the two phases has yet to be undertaken. In this work, we establish a density-functional-theory (DFT)-based approach with Hubbard U correction (DFT + U) to model <span class="hlt">electronic</span> <span class="hlt">transport</span> properties in VO{sub 2} in the semiconducting and metallic regimes, focusing on band <span class="hlt">transport</span> using the Boltzmann <span class="hlt">transport</span> equations. We synthesized high quality VO{sub 2} films and measured the <span class="hlt">transport</span> quantities across the transition, in order to calibrate the free parameters in the model. We find that the experimental calibration of the Hubbard correction term can efficiently and adequately model the metallic and semiconducting phases, allowing for further computational design of MIT materials for desirable <span class="hlt">transport</span> properties.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25909689','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25909689"><span id="translatedtitle">Theoretical investigations into the <span class="hlt">electronic</span> structures and <span class="hlt">electron</span> <span class="hlt">transport</span> properties of fluorine and carbonyl end-functionalized quarterthiophenes.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Li, Qian; Duan, Yuai; Gao, Hong-Ze; Su, Zhong-Мin; Geng, Yun</p> <p>2015-06-01</p> <p>In this work, we concentrate on systematic investigation on the fluorination and carbonylation effect on <span class="hlt">electron</span> <span class="hlt">transport</span> properties of thiophene-based materials with the aim of seeking and designing <span class="hlt">electron</span> <span class="hlt">transport</span> materials. Some relative factors, namely, frontier molecular orbital (FMO), vertical <span class="hlt">electron</span> affinity (VEA), <span class="hlt">electron</span> reorganization energy (λele), <span class="hlt">electron</span> transfer integral (tele), <span class="hlt">electron</span> drift mobility (μele) and band structures have been calculated and discussed based on density functional theory. The results show that the introduction of fluorine atoms and carbonyl group especially for the latter could effectively increase EA and reduce λele, which is beneficial to the improvement of <span class="hlt">electron</span> <span class="hlt">transport</span> performance. Furthermore, these introductions could also affect the tele by changing molecular packing manner and distribution of FMO. Finally, according to our calculation, the 3d system is considered to be a promising <span class="hlt">electron</span> <span class="hlt">transport</span> material with small λele, high <span class="hlt">electron</span> <span class="hlt">transport</span> ability and good ambient stability.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/25909689','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/25909689"><span id="translatedtitle">Theoretical investigations into the <span class="hlt">electronic</span> structures and <span class="hlt">electron</span> <span class="hlt">transport</span> properties of fluorine and carbonyl end-functionalized quarterthiophenes.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Li, Qian; Duan, Yuai; Gao, Hong-Ze; Su, Zhong-Мin; Geng, Yun</p> <p>2015-06-01</p> <p>In this work, we concentrate on systematic investigation on the fluorination and carbonylation effect on <span class="hlt">electron</span> <span class="hlt">transport</span> properties of thiophene-based materials with the aim of seeking and designing <span class="hlt">electron</span> <span class="hlt">transport</span> materials. Some relative factors, namely, frontier molecular orbital (FMO), vertical <span class="hlt">electron</span> affinity (VEA), <span class="hlt">electron</span> reorganization energy (λele), <span class="hlt">electron</span> transfer integral (tele), <span class="hlt">electron</span> drift mobility (μele) and band structures have been calculated and discussed based on density functional theory. The results show that the introduction of fluorine atoms and carbonyl group especially for the latter could effectively increase EA and reduce λele, which is beneficial to the improvement of <span class="hlt">electron</span> <span class="hlt">transport</span> performance. Furthermore, these introductions could also affect the tele by changing molecular packing manner and distribution of FMO. Finally, according to our calculation, the 3d system is considered to be a promising <span class="hlt">electron</span> <span class="hlt">transport</span> material with small λele, high <span class="hlt">electron</span> <span class="hlt">transport</span> ability and good ambient stability. PMID:25909689</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014NatSR...4E5983J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014NatSR...4E5983J"><span id="translatedtitle">Energy level control: toward an efficient hot <span class="hlt">electron</span> <span class="hlt">transport</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jin, Xiao; Li, Qinghua; Li, Yue; Chen, Zihan; Wei, Tai-Huei; He, Xingdao; Sun, Weifu</p> <p>2014-08-01</p> <p>Highly efficient hot <span class="hlt">electron</span> <span class="hlt">transport</span> represents one of the most important properties required for applications in photovoltaic devices. Whereas the fabrication of efficient hot <span class="hlt">electron</span> capture and lost-cost devices remains a technological challenge, regulating the energy level of acceptor-donor system through the incorporation of foreign ions using the solution-processed technique is one of the most promising strategies to overcome this obstacle. Here we present a versatile acceptor-donor system by incorporating MoO3:Eu nanophosphors, which reduces both the `excess' energy offset between the conduction band of acceptor and the lowest unoccupied molecular orbital of donor, and that between the valence band and highest occupied molecular orbital. Strikingly, the hot <span class="hlt">electron</span> transfer time has been shortened. This work demonstrates that suitable energy level alignment can be tuned to gain the higher hot <span class="hlt">electron</span>/hole <span class="hlt">transport</span> efficiency in a simple approach without the need for complicated architectures. This work builds up the foundation of engineering building blocks for third-generation solar cells.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25099864','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25099864"><span id="translatedtitle">Energy level control: toward an efficient hot <span class="hlt">electron</span> <span class="hlt">transport</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Jin, Xiao; Li, Qinghua; Li, Yue; Chen, Zihan; Wei, Tai-Huei; He, Xingdao; Sun, Weifu</p> <p>2014-08-07</p> <p>Highly efficient hot <span class="hlt">electron</span> <span class="hlt">transport</span> represents one of the most important properties required for applications in photovoltaic devices. Whereas the fabrication of efficient hot <span class="hlt">electron</span> capture and lost-cost devices remains a technological challenge, regulating the energy level of acceptor-donor system through the incorporation of foreign ions using the solution-processed technique is one of the most promising strategies to overcome this obstacle. Here we present a versatile acceptor-donor system by incorporating MoO3:Eu nanophosphors, which reduces both the 'excess' energy offset between the conduction band of acceptor and the lowest unoccupied molecular orbital of donor, and that between the valence band and highest occupied molecular orbital. Strikingly, the hot <span class="hlt">electron</span> transfer time has been shortened. This work demonstrates that suitable energy level alignment can be tuned to gain the higher hot <span class="hlt">electron</span>/hole <span class="hlt">transport</span> efficiency in a simple approach without the need for complicated architectures. This work builds up the foundation of engineering building blocks for third-generation solar cells.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/527895','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/527895"><span id="translatedtitle">Multidimensional <span class="hlt">electron</span>-photon <span class="hlt">transport</span> with standard discrete ordinates codes</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Drumm, C.R.</p> <p>1997-04-01</p> <p>A method is described for generating <span class="hlt">electron</span> cross sections that are comparable with standard discrete ordinates codes without modification. There are many advantages of using an established discrete ordinates solver, e.g. immediately available adjoint capability. Coupled <span class="hlt">electron</span>-photon <span class="hlt">transport</span> capability is needed for many applications, including the modeling of the response of <span class="hlt">electronics</span> components to space and man-made radiation environments. The cross sections have been successfully used in the DORT, TWODANT and TORT discrete ordinates codes. The cross sections are shown to provide accurate and efficient solutions to certain multidimensional <span class="hlt">electron</span>-photon <span class="hlt">transport</span> problems. The key to the method is a simultaneous solution of the continuous-slowing-down (CSD) portion and elastic-scattering portion of the scattering source by the Goudsmit-Saunderson theory. The resulting multigroup-Legendre cross sections are much smaller than the true scattering cross sections that they represent. Under certain conditions, the cross sections are guaranteed positive and converge with a low-order Legendre expansion.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/562079','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/562079"><span id="translatedtitle">Multidimensional <span class="hlt">electron</span>-photon <span class="hlt">transport</span> with standard discrete ordinates codes</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Drumm, C.R.</p> <p>1997-09-01</p> <p>A method is described for generating <span class="hlt">electron</span> cross sections that are compatible with standard discrete ordinates codes without modification. There are many advantages to using an established discrete ordinates solver, e.g., immediately available adjoint capability. Coupled <span class="hlt">electron</span>-photon <span class="hlt">transport</span> capability is needed for many applications, including the modeling of the response of <span class="hlt">electronics</span> components to space and synthetic radiation environments. The cross sections have been successfully used in the DORT, TWODANT, and TORT discrete ordinates codes. The cross sections are shown to provide accurate and efficient solutions to certain multidimensional <span class="hlt">electron</span>-photon <span class="hlt">transport</span> problems. The key to the method is a simultaneous solution of the continuous-slowing-down and elastic-scattering portions of the scattering source by the Goudsmit-Saunderson theory. The resulting multigroup-Legendre cross sections are much smaller than the true scattering cross sections that they represent. Under certain conditions, the cross sections are guaranteed positive and converge with a low-order Legendre expansion.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/24132041','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/24132041"><span id="translatedtitle"><span class="hlt">Electron</span> <span class="hlt">transport</span> through a quantum dot assisted by cavity photons.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Abdullah, Nzar Rauf; Tang, Chi-Shung; Manolescu, Andrei; Gudmundsson, Vidar</p> <p>2013-11-20</p> <p>We investigate transient <span class="hlt">transport</span> of <span class="hlt">electrons</span> through a single quantum dot controlled by a plunger gate. The dot is embedded in a finite wire with length Lx assumed to lie along the x-direction with a parabolic confinement in the y-direction. The quantum wire, originally with hard-wall confinement at its ends, ±Lx/2, is weakly coupled at t = 0 to left and right leads acting as external <span class="hlt">electron</span> reservoirs. The central system, the dot and the finite wire, is strongly coupled to a single cavity photon mode. A non-Markovian density-matrix formalism is employed to take into account the full <span class="hlt">electron</span>-photon interaction in the transient regime. In the absence of a photon cavity, a resonant current peak can be found by tuning the plunger-gate voltage to lift a many-body state of the system into the source-drain bias window. In the presence of an x-polarized photon field, additional side peaks can be found due to photon-assisted <span class="hlt">transport</span>. By appropriately tuning the plunger-gate voltage, the <span class="hlt">electrons</span> in the left lead are allowed to undergo coherent inelastic scattering to a two-photon state above the bias window if initially one photon was present in the cavity. However, this photon-assisted feature is suppressed in the case of a y-polarized photon field due to the anisotropy of our system caused by its geometry. PMID:24132041</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JChPh.144l4105R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JChPh.144l4105R"><span id="translatedtitle">Distribution of tunnelling times for quantum <span class="hlt">electron</span> <span class="hlt">transport</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rudge, Samuel L.; Kosov, Daniel S.</p> <p>2016-03-01</p> <p>In <span class="hlt">electron</span> <span class="hlt">transport</span>, the tunnelling time is the time taken for an <span class="hlt">electron</span> to tunnel out of a system after it has tunnelled in. We define the tunnelling time distribution for quantum processes in a dissipative environment and develop a practical approach for calculating it, where the environment is described by the general Markovian master equation. We illustrate the theory by using the rate equation to compute the tunnelling time distribution for <span class="hlt">electron</span> <span class="hlt">transport</span> through a molecular junction. The tunnelling time distribution is exponential, which indicates that Markovian quantum tunnelling is a Poissonian statistical process. The tunnelling time distribution is used not only to study the quantum statistics of tunnelling along the average electric current but also to analyse extreme quantum events where an <span class="hlt">electron</span> jumps against the applied voltage bias. The average tunnelling time shows distinctly different temperature dependence for p- and n-type molecular junctions and therefore provides a sensitive tool to probe the alignment of molecular orbitals relative to the electrode Fermi energy.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/22215491','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22215491"><span id="translatedtitle"><span class="hlt">Electronic</span> <span class="hlt">absorption</span> band broadening and surface roughening of phthalocyanine double layers by saturated solvent vapor treatment</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Kim, Jinhyun; Yim, Sanggyu</p> <p>2012-10-15</p> <p>Variations in the <span class="hlt">electronic</span> <span class="hlt">absorption</span> (EA) and surface morphology of three types of phthalocyanine (Pc) thin film systems, i.e. copper phthalocyanine (CuPc) single layer, zinc phthalocyanine (ZnPc) single layer, and ZnPc on CuPc (CuPc/ZnPc) double layer film, treated with saturated acetone vapor were investigated. For the treated CuPc single layer film, the surface roughness slightly increased and bundles of nanorods were formed, while the EA varied little. In contrast, for the ZnPc single layer film, the relatively high solubility of ZnPc led to a considerable shift in the <span class="hlt">absorption</span> bands as well as a large increase in the surface roughness and formation of long and wide nano-beams, indicating a part of the ZnPc molecules dissolved in acetone, which altered their molecular stacking. For the CuPc/ZnPc film, the saturated acetone vapor treatment resulted in morphological changes in mainly the upper ZnPc layer due to the significantly low solubility of the underlying CuPc layer. The treatment also broadened the EA band, which involved a combination of unchanged CuPc and changed ZnPc <span class="hlt">absorption</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/22217965','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22217965"><span id="translatedtitle">Femtosecond x-ray <span class="hlt">absorption</span> spectroscopy with hard x-ray free <span class="hlt">electron</span> laser</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Katayama, Tetsuo; Togashi, Tadashi; Tono, Kensuke; Kameshima, Takashi; Inubushi, Yuichi; Sato, Takahiro; Hatsui, Takaki; Yabashi, Makina; Obara, Yuki; Misawa, Kazuhiko; Bhattacharya, Atanu; Kurahashi, Naoya; Ogi, Yoshihiro; Suzuki, Toshinori</p> <p>2013-09-23</p> <p>We have developed a method of dispersive x-ray <span class="hlt">absorption</span> spectroscopy with a hard x-ray free <span class="hlt">electron</span> laser (XFEL), generated by a self-amplified spontaneous emission (SASE) mechanism. A transmission grating was utilized for splitting SASE-XFEL light, which has a relatively large bandwidth (ΔE/E ∼ 5 × 10{sup −3}), into several branches. Two primary split beams were introduced into a dispersive spectrometer for measuring signal and reference spectra simultaneously. After normalization, we obtained a Zn K-edge <span class="hlt">absorption</span> spectrum with a photon-energy range of 210 eV, which is in excellent agreement with that measured by a conventional wavelength-scanning method. From the analysis of the difference spectra, the noise ratio was evaluated to be ∼3 × 10{sup −3}, which is sufficiently small to trace minute changes in transient spectra induced by an ultrafast optical laser. This scheme enables us to perform single-shot, high-accuracy x-ray <span class="hlt">absorption</span> spectroscopy with femtosecond time resolution.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26838371','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26838371"><span id="translatedtitle">Control of <span class="hlt">electronic</span> <span class="hlt">transport</span> in graphene by electromagnetic dressing.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kristinsson, K; Kibis, O V; Morina, S; Shelykh, I A</p> <p>2016-01-01</p> <p>We demonstrated theoretically that the renormalization of the <span class="hlt">electron</span> energy spectrum near the Dirac point of graphene by a strong high-frequency electromagnetic field (dressing field) drastically depends on polarization of the field. Namely, linear polarization results in an anisotropic gapless energy spectrum, whereas circular polarization leads to an isotropic gapped one. As a consequence, the stationary (dc) <span class="hlt">electronic</span> <span class="hlt">transport</span> in graphene strongly depends on parameters of the dressing field: A circularly polarized field monotonically decreases the isotropic conductivity of graphene, whereas a linearly polarized one results in both giant anisotropy of conductivity (which can reach thousands of percents) and the oscillating behavior of the conductivity as a function of the field intensity. Since the predicted phenomena can be observed in a graphene layer irradiated by a monochromatic electromagnetic wave, the elaborated theory opens a substantially new way to control <span class="hlt">electronic</span> properties of graphene with light. PMID:26838371</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4738282','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4738282"><span id="translatedtitle">Control of <span class="hlt">electronic</span> <span class="hlt">transport</span> in graphene by electromagnetic dressing</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Kristinsson, K.; Kibis, O. V.; Morina, S.; Shelykh, I. A.</p> <p>2016-01-01</p> <p>We demonstrated theoretically that the renormalization of the <span class="hlt">electron</span> energy spectrum near the Dirac point of graphene by a strong high-frequency electromagnetic field (dressing field) drastically depends on polarization of the field. Namely, linear polarization results in an anisotropic gapless energy spectrum, whereas circular polarization leads to an isotropic gapped one. As a consequence, the stationary (dc) <span class="hlt">electronic</span> <span class="hlt">transport</span> in graphene strongly depends on parameters of the dressing field: A circularly polarized field monotonically decreases the isotropic conductivity of graphene, whereas a linearly polarized one results in both giant anisotropy of conductivity (which can reach thousands of percents) and the oscillating behavior of the conductivity as a function of the field intensity. Since the predicted phenomena can be observed in a graphene layer irradiated by a monochromatic electromagnetic wave, the elaborated theory opens a substantially new way to control <span class="hlt">electronic</span> properties of graphene with light. PMID:26838371</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009PPCF...51l4035P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009PPCF...51l4035P"><span id="translatedtitle">Fast-<span class="hlt">electron</span> <span class="hlt">transport</span> in cylindrically laser-compressed matter</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Perez, F.; Koenig, M.; Batani, D.; Baton, S. D.; Beg, F. N.; Benedetti, C.; Brambrink, E.; Chawla, S.; Dorchies, F.; Fourment, C.; Galimberti, M.; Gizzi, L. A.; Heathcote, R.; Higginson, D. P.; Hulin, S.; Jafer, R.; Koester, P.; Labate, L.; Lancaster, K.; Mac Kinnon, A. J.; McPhee, A. G.; Nazarov, W.; Nicolai, P.; Pasley, J.; Ravasio, A.; Richetta, M.; Santos, J. J.; Sgattoni, A.; Spindloe, C.; Vauzour, B.; Volpe, L.</p> <p>2009-12-01</p> <p>Experimental and theoretical results of relativistic <span class="hlt">electron</span> <span class="hlt">transport</span> in cylindrically compressed matter are presented. This experiment, which is a part of the HiPER roadmap, was achieved on the VULCAN laser facility (UK) using four long pulses beams (~4 × 50 J, 1 ns, at 0.53 µm) to compress a hollow plastic cylinder filled with plastic foam of three different densities (0.1, 0.3 and 1 g cm-3). 2D simulations predict a density of 2-5 g cm-3 and a plasma temperature up to 100 eV at maximum compression. A short pulse (10 ps, 160 J) beam generated fast <span class="hlt">electrons</span> that propagate through the compressed matter by irradiating a nickel foil at an intensity of 5 × 1018 W cm-2. X-ray spectrometer and imagers were implemented in order to estimate the compressed plasma conditions and to infer the hot <span class="hlt">electron</span> characteristics. Results are discussed and compared with simulations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016NatSR...620082K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016NatSR...620082K"><span id="translatedtitle">Control of <span class="hlt">electronic</span> <span class="hlt">transport</span> in graphene by electromagnetic dressing</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kristinsson, K.; Kibis, O. V.; Morina, S.; Shelykh, I. A.</p> <p>2016-02-01</p> <p>We demonstrated theoretically that the renormalization of the <span class="hlt">electron</span> energy spectrum near the Dirac point of graphene by a strong high-frequency electromagnetic field (dressing field) drastically depends on polarization of the field. Namely, linear polarization results in an anisotropic gapless energy spectrum, whereas circular polarization leads to an isotropic gapped one. As a consequence, the stationary (dc) <span class="hlt">electronic</span> <span class="hlt">transport</span> in graphene strongly depends on parameters of the dressing field: A circularly polarized field monotonically decreases the isotropic conductivity of graphene, whereas a linearly polarized one results in both giant anisotropy of conductivity (which can reach thousands of percents) and the oscillating behavior of the conductivity as a function of the field intensity. Since the predicted phenomena can be observed in a graphene layer irradiated by a monochromatic electromagnetic wave, the elaborated theory opens a substantially new way to control <span class="hlt">electronic</span> properties of graphene with light.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li class="active"><span>15</span></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_15 --> <div id="page_16" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active"><span>16</span></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="301"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26838371','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26838371"><span id="translatedtitle">Control of <span class="hlt">electronic</span> <span class="hlt">transport</span> in graphene by electromagnetic dressing.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kristinsson, K; Kibis, O V; Morina, S; Shelykh, I A</p> <p>2016-02-03</p> <p>We demonstrated theoretically that the renormalization of the <span class="hlt">electron</span> energy spectrum near the Dirac point of graphene by a strong high-frequency electromagnetic field (dressing field) drastically depends on polarization of the field. Namely, linear polarization results in an anisotropic gapless energy spectrum, whereas circular polarization leads to an isotropic gapped one. As a consequence, the stationary (dc) <span class="hlt">electronic</span> <span class="hlt">transport</span> in graphene strongly depends on parameters of the dressing field: A circularly polarized field monotonically decreases the isotropic conductivity of graphene, whereas a linearly polarized one results in both giant anisotropy of conductivity (which can reach thousands of percents) and the oscillating behavior of the conductivity as a function of the field intensity. Since the predicted phenomena can be observed in a graphene layer irradiated by a monochromatic electromagnetic wave, the elaborated theory opens a substantially new way to control <span class="hlt">electronic</span> properties of graphene with light.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014PhDT........48J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014PhDT........48J"><span id="translatedtitle"><span class="hlt">Electronic</span> structure measurements of metal-organic solar cell dyes using x-ray <span class="hlt">absorption</span> spectroscopy</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Johnson, Phillip S.</p> <p></p> <p>The focus of this thesis is twofold: to report the results of X-ray <span class="hlt">absorption</span> studies of metal-organic dye molecules for dye-sensitized solar cells and to provide a basic training manual on X-ray <span class="hlt">absorption</span> spectroscopy techniques and data analysis. The purpose of our research on solar cell dyes is to work toward an understanding of the factors influencing the <span class="hlt">electronic</span> structure of the dye: the choice of the metal, its oxidation state, ligands, and cage structure. First we study the effect of replacing Ru in several common dye structures by Fe. First-principles calculations and X-ray <span class="hlt">absorption</span> spectroscopy at the C 1s and N 1s edges are combined to investigate transition metal dyes in octahedral and square planar N cages. Octahedral molecules are found to have a downward shift in the N 1s-to-pi* transition energy and an upward shift in C 1s-to-pi* transition energy when Ru is replaced by Fe, explained by an extra transfer of negative charge from Fe to the N ligands compared to Ru. For the square planar molecules, the behavior is more complex because of the influence of axial ligands and oxidation state. Next the crystal field parameters for a series of phthalocyanine and porphyrins dyes are systematically determined using density functional calculations and atomic multiplet calculations with polarization-dependent X-ray <span class="hlt">absorption</span> spectra. The polarization dependence of the spectra provides information on orbital symmetries which ensures the determination of the crystal field parameters is unique. A uniform downward scaling of the calculated crystal field parameters by 5-30% is found to be necessary to best fit the spectra. This work is a part of the ongoing effort to design and test new solar cell dyes. Replacing the rare metal Ru with abundant metals like Fe would be a significant advance for dye-sensitized solar cells. Understanding the effects of changing the metal centers in these dyes in terms of optical <span class="hlt">absorption</span>, charge transfer, and <span class="hlt">electronic</span></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1999PhDT.......165H&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1999PhDT.......165H&link_type=ABSTRACT"><span id="translatedtitle"><span class="hlt">Electron</span> <span class="hlt">transport</span> and dephasing in semiconductor quantum dots</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Huibers, Andrew Gerrit A.</p> <p></p> <p>At low temperatures, <span class="hlt">electrons</span> in semiconductors can be phase coherent over distances exceeding tens of microns and are sufficiently monochromatic that a variety of interesting quantum interference phenomena can be observed and manipulated. This work discusses <span class="hlt">electron</span> <span class="hlt">transport</span> measurements through cavities (quantum dots) formed by laterally confining <span class="hlt">electrons</span> in the two-dimensional sub-band of a GaAs/AlGaAs heterojunction. Metal gates fabricated using e-beam lithography enable fine control of the cavity shape as well as the leads which connect the dot cavity to source and drain reservoirs. Quantum dots can be modeled by treating the devices as chaotic scatterers. Predictions of this theoretical description are found to be in good quantitative agreement with experimental measurements of full conductance distributions at different temperatures. Weak localization, the suppression of conductance due to phase-coherent backscattering at zero magnetic field, is used to measure dephasing times in the system. Mechanisms responsible for dephasing, including <span class="hlt">electron-electron</span> scattering and Nyquist phase relaxation, are investigated by studying the loss of phase coherence as a function of temperature. Coupling of external microwave fields to the device is also studied to shed light on the unexpected saturation of dephasing that is observed below an <span class="hlt">electron</span> temperature of 100 mK. The effect of external fields in the present experiment is explained in terms of Joule heating from an ac bias.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/21506911','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/21506911"><span id="translatedtitle">Energetic <span class="hlt">Electron</span> <span class="hlt">Transport</span> In An Inhomogeneous Plasma Medium</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Das, Amita</p> <p>2010-11-23</p> <p>A review of the work carried out at IPR on energetic <span class="hlt">electron</span> <span class="hlt">transport</span> through an inhomogeneous plasma medium is presented in this article. A Generalized <span class="hlt">Electron</span> Magnetohydrodynamic (G-EMHD) fluid model has been developed and employed for such studies. Novel observations such as (i) the trapping of <span class="hlt">electron</span> current pulse structure in a high density plasma region, (ii) the formation of sharp magnetic field shock structures at the inhomogeneous plasma density layer (iii) and intense energy dissipation at the shock layer even in the collisionless limit are reported. The intense energy dissipation of the <span class="hlt">electron</span> current pulse at the shock layer provides a mechanism whereby highly energetic <span class="hlt">electrons</span> which are essentially collision-less can also successfully deposit their energy in a local region of the plasma. This is specially attractive as it opens up the possibility of heating a localized region of an overdense plasma (where lasers cannot penetrate) by highly energetic collision-less <span class="hlt">electrons</span>. A direct application of this mechanism to Fast Ignition (FT) experiments is discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4463831','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4463831"><span id="translatedtitle">Chronic intermittent psychological stress promotes macrophage reverse cholesterol <span class="hlt">transport</span> by impairing bile acid <span class="hlt">absorption</span> in mice</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Silvennoinen, Reija; Quesada, Helena; Kareinen, Ilona; Julve, Josep; Kaipiainen, Leena; Gylling, Helena; Blanco-Vaca, Francisco; Escola-Gil, Joan Carles; Kovanen, Petri T; Lee-Rueckert, Miriam</p> <p>2015-01-01</p> <p>Psychological stress is a risk factor for atherosclerosis, yet the pathophysiological mechanisms involved remain elusive. The transfer of cholesterol from macrophage foam cells to liver and feces (the macrophage-specific reverse cholesterol <span class="hlt">transport</span>, m-RCT) is an important antiatherogenic pathway. Because exposure of mice to physical restraint, a model of psychological stress, increases serum levels of corticosterone, and as bile acid homeostasis is disrupted in glucocorticoid-treated animals, we investigated if chronic intermittent restraint stress would modify m-RCT by altering the enterohepatic circulation of bile acids. C57Bl/6J mice exposed to intermittent stress for 5 days exhibited increased transit through the large intestine and enhanced fecal bile acid excretion. Of the transcription factors and <span class="hlt">transporters</span> that regulate bile acid homeostasis, the mRNA expression levels of the hepatic farnesoid X receptor (FXR), the bile salt export pump (BSEP), and the intestinal fibroblast growth factor 15 (FGF15) were reduced, whereas those of the ileal apical sodium-dependent bile acid <span class="hlt">transporter</span> (ASBT), responsible for active bile acid <span class="hlt">absorption</span>, remained unchanged. Neither did the hepatic expression of cholesterol 7α-hydroxylase (CYP7A1), the key enzyme regulating bile acid synthesis, change in the stressed mice. Evaluation of the functionality of the m-RCT pathway revealed increased fecal excretion of bile acids that had been synthesized from macrophage-derived cholesterol. Overall, our study reveals that chronic intermittent stress in mice accelerates m-RCT specifically by increasing fecal excretion of bile acids. This novel mechanism of m-RCT induction could have antiatherogenic potential under conditions of chronic stress. PMID:25969465</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/11015866','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/11015866"><span id="translatedtitle">Bound states in optical <span class="hlt">absorption</span> of semiconductor quantum wells containing a two-dimensional <span class="hlt">electron</span> Gas</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Huard; Cox; Saminadayar; Arnoult; Tatarenko</p> <p>2000-01-01</p> <p>The dependence of the optical <span class="hlt">absorption</span> spectrum of a semiconductor quantum well on two-dimensional <span class="hlt">electron</span> concentration n(e) is studied using CdTe samples. The trion peak (X-) seen at low n(e) evolves smoothly into the Fermi edge singularity at high n(e). The exciton peak (X) moves off to high energy, weakens, and disappears. The X,X- splitting is linear in n(e) and closely equal to the Fermi energy plus the trion binding energy. For Cd0.998Mn0.002Te quantum wells in a magnetic field, the X,X- splitting reflects unequal Fermi energies for M = +/-1/2 <span class="hlt">electrons</span>. The data are explained by Hawrylak's theory of the many-body optical response including spin effects.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19740039600&hterms=electron+atoms&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Delectron%2Batoms','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19740039600&hterms=electron+atoms&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Delectron%2Batoms"><span id="translatedtitle">Free-free <span class="hlt">absorption</span> of infrared radiation in collisions of <span class="hlt">electrons</span> with neutral rare-gas atoms</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Stallcop, J. R.</p> <p>1974-01-01</p> <p>A relationship between the inverse bremsstrahlung <span class="hlt">absorption</span> cross section and the <span class="hlt">electron</span> neutral momentum transfer cross section has been utilized to determine the infrared free-free continuum <span class="hlt">absorption</span> coefficient for the negative ions of helium, neon, argon, krypton, and xenon. The values of the momentum transfer cross section for this calculation have been obtained from experimental measurements. Analytical expressions for the <span class="hlt">absorption</span> coefficient have also been developed. From the results of this calculation, it is possible to determine the <span class="hlt">absorption</span> coefficient per unit <span class="hlt">electron</span> density per neutral atom for temperatures in the range from 2500 to 25,000 K. The results are compared with those from tabulations of previous calculations and those computed from theoretical values of the phase shifts for the elastic scattering of <span class="hlt">electrons</span> by neutral atoms.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003APS..MARA22008B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003APS..MARA22008B"><span id="translatedtitle">Dissipative <span class="hlt">electronic</span> <span class="hlt">transport</span> through double quantum dots irradiated with microwaves</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Brandes, Tobias; Aguado, Ramon; Platero, Gloria</p> <p>2003-03-01</p> <p>Double quantum dots in the strong Coulomb blockade regime are realizations of two-level systems defined from two tunnel--splitted ground states, which are separated by a large energy gap from the remaining many--particle states. The interactions between <span class="hlt">electrons</span> and bosonic degrees of freedom (photons, phonons) in these systems can be tested and manipulated in <span class="hlt">electronic</span> <span class="hlt">transport</span> experiments [1]. Monochromatic classical radiation (AC fields, microwaves) gives rise to various non-linear effects such as photo-sidebands or dynamical localization (coherent supression of tunneling) that show up in the time-averaged, stationary <span class="hlt">electronic</span> current [2]. On the other hand, quantum noise of a dissipative environment strongly influences the <span class="hlt">transport</span> properties of coupled quantum dots [3,4]. In this contribution, we quantitatively investigate the combined influence of a classical, monochromatic time-dependent AC field and a dissipative boson environment on the non-linear <span class="hlt">transport</span> through a double quantum dot. We develop a Floquet-like theory [5] that takes into account the effect of the <span class="hlt">electron</span> reservoirs (leads) and can be numerically evaluated for arbitrary strong AC fields and arbitrary boson environment. In limiting cases we reproduce previous analytical results (polaron tunneling, Tien-Gordon formula). [1] T. Fujisawa, T. H. Oosterkamp, W. G. van der Wiel, B. W. Broer, R. Aguado, S. Tarucha, and L. P. Kouwenhoven, Science 282, 932 (1998); R. H. Blick, D. Pfannkuche, R. J. Haug, K. v. Klitzing, and K. Eberl, Phys. Rev. Lett. 80, 4032 (1998). [2] T. H. Stoof, Yu. V. Nazarov, Phys. Rev. B 53, 1050 (1996). [3] T. Brandes, B. Kramer, Phys. Rev. Lett. 83, 3021 (1999); T. Brandes, F. Renzoni, R. H. Blick, Phys. Rev. B 64, 035319 (2001); T. Brandes, T. Vorrath, Phys. Rev. B 66, 075341 (2002). [4] R. Aguado and L. P. Kouwenhoven, Phys. Rev. Lett, 84, 1986 (2000). [5] M. Grifoni, P. Hänggi, Phys. Rep. 304, 229 (1998).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27023202','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27023202"><span id="translatedtitle">Dietary Lipid and Carbohydrate Interactions: Implications on Lipid and Glucose <span class="hlt">Absorption</span>, <span class="hlt">Transport</span> in Gilthead Sea Bream (Sparus aurata) Juveniles.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Castro, Carolina; Corraze, Geneviève; Basto, Ana; Larroquet, Laurence; Panserat, Stéphane; Oliva-Teles, Aires</p> <p>2016-06-01</p> <p>A digestibility trial was performed with gilthead sea bream juveniles (IBW = 72 g) fed four diets differing in lipid source (fish oil, FO; or a blend of vegetable oil, VO) and starch content (0 %, CH-; or 20 %, CH+) to evaluate the potential interactive effects between carbohydrates and VO on the processes involved in digestion, <span class="hlt">absorption</span> and <span class="hlt">transport</span> of lipids and glucose. In fish fed VO diets a decrease in lipid digestibility and in cholesterol (C), High Density Lipoprotein(HDL)-C and Low Density Lipoprotein (LDL)-C (only in CH+ group) were recorded. Contrarily, dietary starch induced postprandial hyperglycemia and time related alterations on serum triacylglycerol (TAG), phospholipid (PL) and C concentrations. Fish fed a CH+ diet presented lower serum TAG than CH- group at 6 h post-feeding, and the reverse was observed at 12 h post-feeding for TAG and PL. Lower serum C and PL at 6 h post-feeding were recorded only in VOCH+ group. No differences between groups were observed in hepatic and intestinal transcript levels of proteins involved in lipid <span class="hlt">transport</span> and hydrolysis (FABP, DGAT, GPAT, MTP, LPL, LCAT). Lower transcript levels of proteins related to lipid <span class="hlt">transport</span> (ApoB, ApoA1, FABP2) were observed in the intestine of fish fed the CH+ diet, but remained unchanged in the liver. Overall, transcriptional mechanisms involved in lipid <span class="hlt">transport</span> and <span class="hlt">absorption</span> were not linked to changes in lipid serum and digestibility. Dietary starch affected lipid <span class="hlt">absorption</span> and <span class="hlt">transport</span>, probably due to a delay in lipid <span class="hlt">absorption</span>. This study suggests that a combination of dietary VO and starch may negatively affect cholesterol <span class="hlt">absorption</span> and <span class="hlt">transport</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/27023202','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/27023202"><span id="translatedtitle">Dietary Lipid and Carbohydrate Interactions: Implications on Lipid and Glucose <span class="hlt">Absorption</span>, <span class="hlt">Transport</span> in Gilthead Sea Bream (Sparus aurata) Juveniles.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Castro, Carolina; Corraze, Geneviève; Basto, Ana; Larroquet, Laurence; Panserat, Stéphane; Oliva-Teles, Aires</p> <p>2016-06-01</p> <p>A digestibility trial was performed with gilthead sea bream juveniles (IBW = 72 g) fed four diets differing in lipid source (fish oil, FO; or a blend of vegetable oil, VO) and starch content (0 %, CH-; or 20 %, CH+) to evaluate the potential interactive effects between carbohydrates and VO on the processes involved in digestion, <span class="hlt">absorption</span> and <span class="hlt">transport</span> of lipids and glucose. In fish fed VO diets a decrease in lipid digestibility and in cholesterol (C), High Density Lipoprotein(HDL)-C and Low Density Lipoprotein (LDL)-C (only in CH+ group) were recorded. Contrarily, dietary starch induced postprandial hyperglycemia and time related alterations on serum triacylglycerol (TAG), phospholipid (PL) and C concentrations. Fish fed a CH+ diet presented lower serum TAG than CH- group at 6 h post-feeding, and the reverse was observed at 12 h post-feeding for TAG and PL. Lower serum C and PL at 6 h post-feeding were recorded only in VOCH+ group. No differences between groups were observed in hepatic and intestinal transcript levels of proteins involved in lipid <span class="hlt">transport</span> and hydrolysis (FABP, DGAT, GPAT, MTP, LPL, LCAT). Lower transcript levels of proteins related to lipid <span class="hlt">transport</span> (ApoB, ApoA1, FABP2) were observed in the intestine of fish fed the CH+ diet, but remained unchanged in the liver. Overall, transcriptional mechanisms involved in lipid <span class="hlt">transport</span> and <span class="hlt">absorption</span> were not linked to changes in lipid serum and digestibility. Dietary starch affected lipid <span class="hlt">absorption</span> and <span class="hlt">transport</span>, probably due to a delay in lipid <span class="hlt">absorption</span>. This study suggests that a combination of dietary VO and starch may negatively affect cholesterol <span class="hlt">absorption</span> and <span class="hlt">transport</span>. PMID:27023202</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012asim.book..119Q','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012asim.book..119Q"><span id="translatedtitle">Probing <span class="hlt">Electronic</span> <span class="hlt">Transport</span> of Individual Nanostructures with Atomic Precision</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Qin, Shengyong; Li, An-Ping</p> <p></p> <p>Accessing individual nanostructures with atomic precision is an important process in the bottom-up fabrication and characterization of <span class="hlt">electronic</span> nanodevices. Local electrical contacts, namely nanoelectrodes, are often fabricated by using top-down lithography and chemical etching techniques. These processes however lack atomic precision and introduce the possibility of contamination. Here, we review recent reports on the application of a field-induced emission process in the fabrication of local contacts onto individual nanowires and nanotubes with atomic spatial precision. In this method, gold nanoislands are deposited onto nanostructures precisely by using a scanning tunneling microscope tip, which provides a clean and controllable process to ensure both electrically conductive and mechanically reliable contacts. The applicability of the technique has been demonstrated in a wide variety of nanostructures, including silicide atomic wires, carbon nanotubes, and copper nanowires. These local contacts bridge the nanostructures and the <span class="hlt">transport</span> probes, allowing for the measurements of both electrical <span class="hlt">transport</span> and scanning tunneling microscopy on the same nanostructures in situ. The direct correlation between <span class="hlt">electronic</span> and <span class="hlt">transport</span> properties and atomic structures can be explored on individual nanostructures at the unprecedented atomic level.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/1040753','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/1040753"><span id="translatedtitle">Probing <span class="hlt">electronic</span> <span class="hlt">transport</span> of individual nanostructures with atomic precision</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Qin, Shengyong; Li, An-Ping</p> <p>2012-01-01</p> <p>Accessing individual nanostructures with atomic precision is an important process in the bottom-up fabrication and characterization of <span class="hlt">electronic</span> nanodevices. Local electrical contacts, namely nanoelectrodes, are often fabricated by using top-down lithography and chemical etching techniques. These processes however lack atomic precision and introduce the possibility of contamination. Here, we review recent reports on the application of a field-induced emission process in the fabrication of local contacts onto individual nanowires and nanotubes with atomic spatial precision. In this method, gold nanoislands are deposited onto nanostructures precisely by using a scanning tunneling microscope tip, which provides a clean and controllable process to ensure both electrically conductive and mechanically reliable contacts. The applicability of the technique has been demonstrated in a wide variety of nanostructures, including silicide atomic wires, carbon nanotubes, and copper nanowires. These local contacts bridge the nanostructures and the <span class="hlt">transport</span> probes, allowing for the measurements of both electrical <span class="hlt">transport</span> and scanning tunneling microscopy on the same nanostructures in situ. The direct correlation between <span class="hlt">electronic</span> and <span class="hlt">transport</span> properties and atomic structures can be explored on individual nanostructures at the unprecedented atomic level.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/accomplishments/documents/fullText/ACC0141.pdf','DOE-RDACC'); return false;" href="http://www.osti.gov/accomplishments/documents/fullText/ACC0141.pdf"><span id="translatedtitle">Helium, Iron and <span class="hlt">Electron</span> Particle <span class="hlt">Transport</span> and Energy <span class="hlt">Transport</span> Studies on the TFTR Tokamak</span></a></p> <p><a target="_blank" href="http://www.osti.gov/accomplishments/fieldedsearch.html">DOE R&D Accomplishments Database</a></p> <p>Synakowski, E. J.; Efthimion, P. C.; Rewoldt, G.; Stratton, B. C.; Tang, W. M.; Grek, B.; Hill, K. W.; Hulse, R. A.; Johnson, D .W.; Mansfield, D. K.; McCune, D.; Mikkelsen, D. R.; Park, H. K.; Ramsey, A. T.; Redi, M. H.; Scott, S. D.; Taylor, G.; Timberlake, J.; Zarnstorff, M. C. (Princeton Univ., NJ (United States). Plasma Physics Lab.); Kissick, M. W. (Wisconsin Univ., Madison, WI (United States))</p> <p>1993-03-01</p> <p>Results from helium, iron, and <span class="hlt">electron</span> <span class="hlt">transport</span> on TFTR in L-mode and Supershot deuterium plasmas with the same toroidal field, plasma current, and neutral beam heating power are presented. They are compared to results from thermal <span class="hlt">transport</span> analysis based on power balance. Particle diffusivities and thermal conductivities are radially hollow and larger than neoclassical values, except possibly near the magnetic axis. The ion channel dominates over the <span class="hlt">electron</span> channel in both particle and thermal diffusion. A peaked helium profile, supported by inward convection that is stronger than predicted by neoclassical theory, is measured in the Supershot The helium profile shape is consistent with predictions from quasilinear electrostatic drift-wave theory. While the perturbative particle diffusion coefficients of all three species are similar in the Supershot, differences are found in the L-Mode. Quasilinear theory calculations of the ratios of impurity diffusivities are in good accord with measurements. Theory estimates indicate that the ion heat flux should be larger than the <span class="hlt">electron</span> heat flux, consistent with power balance analysis. However, theoretical values of the ratio of the ion to <span class="hlt">electron</span> heat flux can be more than a factor of three larger than experimental values. A correlation between helium diffusion and ion thermal <span class="hlt">transport</span> is observed and has favorable implications for sustained ignition of a tokamak fusion reactor.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/10141674','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/10141674"><span id="translatedtitle">Helium, iron and <span class="hlt">electron</span> particle <span class="hlt">transport</span> and energy <span class="hlt">transport</span> studies on the TFTR tokamak</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Synakowski, E.J.; Efthimion, P.C.; Rewoldt, G.; Stratton, B.C.; Tang, W.M.; Grek, B.; Hill, K.W.; Hulse, R.A.; Johnson, D.W.; Mansfield, D.K.; McCune, D.; Mikkelsen, D.R.; Park, H.K.; Ramsey, A.T.; Redi, M.H.; Scott, S.D.; Taylor, G.; Timberlake, J.; Zarnstorff, M.C.; Kissick, M.W.</p> <p>1993-03-01</p> <p>Results from helium, iron, and <span class="hlt">electron</span> <span class="hlt">transport</span> on TFTR in L-mode and Supershot deuterium plasmas with the same toroidal field, plasma current, and neutral beam heating power are presented. They are compared to results from thermal <span class="hlt">transport</span> analysis based on power balance. Particle diffusivities and thermal conductivities are radially hollow and larger than neoclassical values, except possibly near the magnetic axis. The ion channel dominates over the <span class="hlt">electron</span> channel in both particle and thermal diffusion. A peaked helium profile, supported by inward convection that is stronger than predicted by neoclassical theory, is measured in the Supershot The helium profile shape is consistent with predictions from quasilinear electrostatic drift-wave theory. While the perturbative particle diffusion coefficients of all three species are similar in the Supershot, differences are found in the L-Mode. Quasilinear theory calculations of the ratios of impurity diffusivities are in good accord with measurements. Theory estimates indicate that the ion heat flux should be larger than the <span class="hlt">electron</span> heat flux, consistent with power balance analysis. However, theoretical values of the ratio of the ion to <span class="hlt">electron</span> heat flux can be more than a factor of three larger than experimental values. A correlation between helium diffusion and ion thermal <span class="hlt">transport</span> is observed and has favorable implications for sustained ignition of a tokamak fusion reactor.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015PhDT........73D&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015PhDT........73D&link_type=ABSTRACT"><span id="translatedtitle">Understanding <span class="hlt">electronic</span> structure and <span class="hlt">transport</span> properties in nanoscale junctions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dhungana, Kamal B.</p> <p></p> <p>Understanding the <span class="hlt">electronic</span> structure and the <span class="hlt">transport</span> properties of nanoscale materials are pivotal for designing future nano-scale <span class="hlt">electronic</span> devices. Nanoscale materials could be individual or groups of molecules, nanotubes, semiconducting quantum dots, and biomolecules. Among these several alternatives, organic molecules are very promising and the field of molecular <span class="hlt">electronics</span> has progressed significantly over the past few decades. Despite these progresses, it has not yet been possible to achieve atomic level control at the metal-molecule interface during a conductance measurement, which hinders the progress in this field. The lack of atomic level information of the interface also makes it much harder for theorist to interpret the experimental results. To identify the junction configuration that possibly exists during the experimental measurement of conductance in molecular junction, we created an ensemble of Ruthanium-bis(terpyridine) molecular devices, and studied the <span class="hlt">transport</span> behavior in these molecular junctions. This helps us identifying the junction geometry that yields the experimentally measured current-voltage characteristics. Today's <span class="hlt">electronic</span> devices mostly ignore the spin effect of an <span class="hlt">electron</span>. The inclusion of spin effect of an <span class="hlt">electron</span> on solid-state transistor allows us to build more efficient <span class="hlt">electronic</span> devices; this also alleviates the problem of huge heat dissipation in the nanoscale <span class="hlt">electronic</span> devices. Different materials have been utilized to build three terminals spin transistor since its inception in 1950. In search of suitable candidates for the molecular spin transistor, we have recently designed a spin-valve transistor based on an organometallic molecule; a large amplification (320 %) in tunnel magneto-resistance (TMR) is found to occur at an experimentally accessible gate field. This suggests that the organic molecules can be utilized for making the next generation three terminal spintronic devices. Similarly, we have designed a</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4106716','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4106716"><span id="translatedtitle">Comparative analysis of discrete and continuous <span class="hlt">absorption</span> weighting estimators used in Monte Carlo simulations of radiative <span class="hlt">transport</span> in turbid media</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Hayakawa, Carole K.; Spanier, Jerome; Venugopalan, Vasan</p> <p>2014-01-01</p> <p>We examine the relative error of Monte Carlo simulations of radiative <span class="hlt">transport</span> that employ two commonly used estimators that account for <span class="hlt">absorption</span> differently, either discretely, at interaction points, or continuously, between interaction points. We provide a rigorous derivation of these discrete and continuous <span class="hlt">absorption</span> weighting estimators within a stochastic model that we show to be equivalent to an analytic model, based on the radiative <span class="hlt">transport</span> equation (RTE). We establish that both <span class="hlt">absorption</span> weighting estimators are unbiased and, therefore, converge to the solution of the RTE. An analysis of spatially resolved reflectance predictions provided by these two estimators reveals no advantage to either in cases of highly scattering and highly anisotropic media. However, for moderate to highly absorbing media or isotropically scattering media, the discrete estimator provides smaller errors at proximal source locations while the continuous estimator provides smaller errors at distal locations. The origin of these differing variance characteristics can be understood through examination of the distribution of exiting photon weights. PMID:24562029</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015APS..MARQ41005S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015APS..MARQ41005S"><span id="translatedtitle">Predicting X-ray <span class="hlt">absorption</span> spectra of semiconducting polymers for <span class="hlt">electronic</span> structure and morphology characterization</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Su, Gregory; Patel, Shrayesh; Pemmaraju, C. Das; Kramer, Edward; Prendergast, David; Chabinyc, Michael</p> <p>2015-03-01</p> <p>Core-level X-ray <span class="hlt">absorption</span> spectroscopy (XAS) reveals important information on the <span class="hlt">electronic</span> structure of materials and plays a key role in morphology characterization. Semiconducting polymers are the active component in many organic <span class="hlt">electronics</span>. Their <span class="hlt">electronic</span> properties are critically linked to device performance, and a proper understanding of semiconducting polymer XAS is crucial. Techniques such as resonant X-ray scattering rely on core-level transitions to gain materials contrast and probe orientational order. However, it is difficult to identify these transitions based on experiments alone, and complementary simulations are required. We show that first-principles calculations can capture the essential features of experimental XAS of semiconducting polymers, and provide insight into which molecular model, such as oligomers or periodic boundary conditions, are best suited for XAS calculations. Simulated XAS can reveal contributions from individual atoms and be used to visualize molecular orbitals. This allows for improved characterization of molecular orientation and scattering analysis. These predictions lay the groundwork for understanding how chemical makeup is linked to <span class="hlt">electronic</span> structure, and to properly utilize experiments to characterize semiconducting polymers.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/22412974','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22412974"><span id="translatedtitle"><span class="hlt">Electron</span> and hole <span class="hlt">transport</span> in ambipolar, thin film pentacene transistors</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Saudari, Sangameshwar R.; Kagan, Cherie R.</p> <p>2015-01-21</p> <p>Solution-processed, ambipolar, thin-film pentacene field-effect transistors were employed to study both <span class="hlt">electron</span> and hole <span class="hlt">transport</span> simultaneously in a single, organic solid-state device. <span class="hlt">Electron</span> and hole mobilities were extracted from the respective unipolar saturation regimes and show thermally activated behavior and gate voltage dependence. We fit the gate voltage dependent saturation mobility to a power law to extract the characteristic Meyer-Neldel (MN) energy, a measure of the width of the exponential distribution of localized states extending into the energy gap of the organic semiconductor. The MN energy is ∼78 and ∼28 meV for <span class="hlt">electrons</span> and holes, respectively, which reflects a greater density of localized tail states for <span class="hlt">electrons</span> than holes. This is consistent with the lower measured <span class="hlt">electron</span> than hole mobility. For holes, the well-behaved linear regime allows for four-point probe measurement of the contact resistance independent mobility and separate characterization of the width of the localized density of states, yielding a consistent MN energy of 28 meV.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4791957','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4791957"><span id="translatedtitle">Nanoscale <span class="hlt">Electron</span> <span class="hlt">Transport</span> Measurements of Immobilized Cytochrome P450 Proteins</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Bostick, Christopher D.; Flora, Darcy R.; Gannett, Peter M.; Tracy, Timothy S.; Lederman, David</p> <p>2015-01-01</p> <p>Gold nanopillars, functionalized with an organic self-assembled monolayer, can be used to measure the electrical conductance properties of immobilized proteins without aggregation. Measurements of the conductance of nanopillars with cytochrome P450 2C9 (CYP2C9) proteins using conducting probe atomic force microscopy demonstrate that a correlation exists between the energy barrier height between hopping sites and CYP2C9 metabolic activity. Measurements performed as a function of tip force indicate that, when subjected to a large force, the protein is more stable in the presence of a substrate. This agrees with the hypothesis that substrate entry into the active site helps to stabilize the enzyme. The relative distance between hopping sites also increases with increasing force, possibly because protein functional groups responsible for <span class="hlt">electron</span> <span class="hlt">transport</span> depend on the structure of the protein. The inhibitor sulfaphenazole, in addition to the previously studied aniline, increased the barrier height for <span class="hlt">electron</span> transfer and thereby makes CYP2C9 reduction more difficult and inhibits metabolism. This suggests that P450 Type II binders may decrease the ease of <span class="hlt">electron</span> <span class="hlt">transport</span> processes in the enzyme, in addition to occupying the active site. PMID:25804257</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3552782','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3552782"><span id="translatedtitle"><span class="hlt">Electron</span> <span class="hlt">transport</span> in a GaPSb film</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p></p> <p>2012-01-01</p> <p>We have performed <span class="hlt">transport</span> measurements on a gallium phosphide antimonide (GaPSb) film grown on GaAs. At low temperatures (T), <span class="hlt">transport</span> is governed by three-dimensional Mott variable range hopping (VRH) due to strong localization. Therefore, electron–<span class="hlt">electron</span> interactions are not significant in GaPSb. With increasing T, the coexistence of VRH conduction and the activated behavior with a gap of 20 meV is found. The fact that the measured gap is comparable to the thermal broadening at room temperature (approximately 25 meV) demonstrates that <span class="hlt">electrons</span> can be thermally activated in an intrinsic GaPSb film. Moreover, the observed carrier density dependence on temperature also supports the coexistence of VRH and the activated behavior. It is shown that the carriers are delocalized either with increasing temperature or magnetic field in GaPSb. Our new experimental results provide important information regarding GaPSb which may well lay the foundation for possible GaPSb-based device applications such as in high-<span class="hlt">electron</span>-mobility transistor and heterojunction bipolar transistors. PMID:23173952</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active"><span>16</span></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_16 --> <div id="page_17" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active"><span>17</span></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="321"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2806741','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2806741"><span id="translatedtitle">Electrokinesis is a microbial behavior that requires extracellular <span class="hlt">electron</span> <span class="hlt">transport</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Harris, H. W.; El-Naggar, M. Y.; Bretschger, O.; Ward, M. J.; Romine, M. F.; Obraztsova, A. Y.; Nealson, K. H.</p> <p>2009-01-01</p> <p>We report a previously undescribed bacterial behavior termed electrokinesis. This behavior was initially observed as a dramatic increase in cell swimming speed during reduction of solid MnO2 particles by the dissimilatory metal-reducing bacterium Shewanella oneidensis MR-1. The same behavioral response was observed when cells were exposed to small positive applied potentials at the working electrode of a microelectrochemical cell and could be tuned by adjusting the potential on the working electrode. Electrokinesis was found to be different from both chemotaxis and galvanotaxis but was absent in mutants defective in <span class="hlt">electron</span> <span class="hlt">transport</span> to solid metal oxides. Using in situ video microscopy and cell tracking algorithms, we have quantified the response for different strains of Shewanella and shown that the response correlates with current-generating capacity in microbial fuel cells. The electrokinetic response was only exhibited by a subpopulation of cells closest to the MnO2 particles or electrodes. In contrast, the addition of 1 mM 9,10-anthraquinone-2,6-disulfonic acid, a soluble <span class="hlt">electron</span> shuttle, led to increases in motility in the entire population. Electrokinesis is defined as a behavioral response that requires functional extracellular <span class="hlt">electron</span> <span class="hlt">transport</span> and that is observed as an increase in cell swimming speeds and lengthened paths of motion that occur in the proximity of a redox active mineral surface or the working electrode of an electrochemical cell. PMID:20018675</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010APS..MART16001N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010APS..MART16001N"><span id="translatedtitle">Multiscale modelling of charge <span class="hlt">transport</span> in organic <span class="hlt">electronic</span> materials</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nelson, Jenny</p> <p>2010-03-01</p> <p>Charge <span class="hlt">transport</span> in disordered organic semiconductors is controlled by a complex combination of phenomena that span a range of length and time scales. As a result, it is difficult to rationalize charge <span class="hlt">transport</span> properties in terms of material parameters. Until now, efforts to improve charge mobilities in molecular semiconductors have proceeded largely by trial and error rather than through systematic design. However, recent developments have enabled the first predictive simulation studies of charge <span class="hlt">transport</span> in disordered organic semiconductors. In this presentation we will show how a set of computational methods, namely molecular modelling methods to simulate molecular packing, quantum chemical calculations of charge transfer rates, and Monte Carlo simulations of charge <span class="hlt">transport</span> can be used to reproduce experimental charge mobilities with few or no fitting parameters. Using case studies, we will show how such simulations can explain the relative values of <span class="hlt">electron</span> and hole mobility and the effects of grain size, side chains and polymer molecular weight on charge mobility. Although currently applied to material systems of relatively high symmetry or well defined structure, this approach can be developed to address more complex systems such as multicomponent solids and conjugated polymers.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015Nanos...715284H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015Nanos...715284H"><span id="translatedtitle">Epitaxial 1D <span class="hlt">electron</span> <span class="hlt">transport</span> layers for high-performance perovskite solar cells</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Han, Gill Sang; Chung, Hyun Suk; Kim, Dong Hoe; Kim, Byeong Jo; Lee, Jin-Wook; Park, Nam-Gyu; Cho, In Sun; Lee, Jung-Kun; Lee, Sangwook; Jung, Hyun Suk</p> <p>2015-09-01</p> <p>We demonstrate high-performance perovskite solar cells with excellent <span class="hlt">electron</span> <span class="hlt">transport</span> properties using a one-dimensional (1D) <span class="hlt">electron</span> <span class="hlt">transport</span> layer (ETL). The 1D array-based ETL is comprised of 1D SnO2 nanowires (NWs) array grown on a F:SnO2 transparent conducting oxide substrate and rutile TiO2 nanoshells epitaxially grown on the surface of the 1D SnO2 NWs. The optimized devices show more than 95% internal quantum yield at 750 nm, and a power conversion efficiency (PCE) of 14.2%. The high quantum yield is attributed to dramatically enhanced <span class="hlt">electron</span> <span class="hlt">transport</span> in the epitaxial TiO2 layer, compared to that in conventional nanoparticle-based mesoporous TiO2 (mp-TiO2) layers. In addition, the open space in the 1D array-based ETL increases the prevalence of uniform TiO2/perovskite junctions, leading to reproducible device performance with a high fill factor. This work offers a method to achieve reproducible, high-efficiency perovskite solar cells with high-speed <span class="hlt">electron</span> <span class="hlt">transport</span>.We demonstrate high-performance perovskite solar cells with excellent <span class="hlt">electron</span> <span class="hlt">transport</span> properties using a one-dimensional (1D) <span class="hlt">electron</span> <span class="hlt">transport</span> layer (ETL). The 1D array-based ETL is comprised of 1D SnO2 nanowires (NWs) array grown on a F:SnO2 transparent conducting oxide substrate and rutile TiO2 nanoshells epitaxially grown on the surface of the 1D SnO2 NWs. The optimized devices show more than 95% internal quantum yield at 750 nm, and a power conversion efficiency (PCE) of 14.2%. The high quantum yield is attributed to dramatically enhanced <span class="hlt">electron</span> <span class="hlt">transport</span> in the epitaxial TiO2 layer, compared to that in conventional nanoparticle-based mesoporous TiO2 (mp-TiO2) layers. In addition, the open space in the 1D array-based ETL increases the prevalence of uniform TiO2/perovskite junctions, leading to reproducible device performance with a high fill factor. This work offers a method to achieve reproducible, high-efficiency perovskite solar cells with high-speed <span class="hlt">electron</span> <span class="hlt">transport</span></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/1036575','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/1036575"><span id="translatedtitle">Contacting nanowires and nanotubes with atomic precision for <span class="hlt">electronic</span> <span class="hlt">transport</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Qin, Shengyong; Hellstrom, Sondra L; Bao, Zhenan; Boyanov, Boyan; Li, An-Ping</p> <p>2012-01-01</p> <p>Making contacts to nanostructures with atomic precision is an important process in the bottom-up fabrication and characterization of <span class="hlt">electronic</span> nanodevices. Existing contacting techniques use top-down lithography and chemical etching, but lack atomic precision and introduce the possibility of contamination. Here, we report that a field-induced emission process can be used to make local contacts onto individual nanowires and nanotubes with atomic spatial precision. The gold nano-islands are deposited onto nanostructures precisely by using a scanning tunneling microscope tip, which provides a clean and controllable method to ensure both electrically conductive and mechanically reliable contacts. To demonstrate the wide applicability of the technique, nano-contacts are fabricated on silicide atomic wires, carbon nanotubes, and copper nanowires. The electrical <span class="hlt">transport</span> measurements are performed in situ by utilizing the nanocontacts to bridge the nanostructures to the <span class="hlt">transport</span> probes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002JMMM..240..117F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002JMMM..240..117F"><span id="translatedtitle"><span class="hlt">Transport</span> properties and <span class="hlt">electronic</span> structure of epitaxial tunnel junctions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Freyss, M.; Papanikolaou, N.; Bellini, V.; Zeller, R.; Dederichs, P. H.; Turek, I.</p> <p>2002-02-01</p> <p>We present ab initio calculations for the <span class="hlt">electronic</span> ground-state and <span class="hlt">transport</span> properties of epitaxial Fe/semiconductor/Fe (0 0 1) tunnel junctions. The ground state properties are determined by the ab initio Screened KKR Green's function method and the <span class="hlt">transport</span> properties by a Green's function formulation of the Landauer-Büttiker formalism. We focus on tunnel junctions with a semiconducting ZnSe barrier and compare them to results for junctions with Si and GaAs barriers. We comment on the presence of metal-induced gap states (MIGS) in the semiconductor, the spin polarization of which strongly depends on the nature of the barrier. We investigate furthermore the influence of one atomic layer at the interface of a non-magnetic metal (Cu, Ag, Al) and of a magnetic 3d transition metal.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/5197113','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/5197113"><span id="translatedtitle">Conservative differencing of the <span class="hlt">electron</span> Fokker-Planck <span class="hlt">transport</span> equation</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Langdon, A.B.</p> <p>1981-01-12</p> <p>We need to extend the applicability and improve the accuracy of kinetic <span class="hlt">electron</span> <span class="hlt">transport</span> codes. In this paper, special attention is given to modelling of e-e collisions, including the dominant contributions arising from anisotropy. The electric field and spatial gradient terms are also considered. I construct finite-difference analogues to the Fokker-Planck integral-differential collision operator, which conserve the particle number, momentum and energy integrals (sums) regardless of the coarseness of the velocity zoning. Such properties are usually desirable, but are especially useful, for example, when there are spatial regions and/or time intervals in which the plasma is cool, so that the collision operator acts rapidly and the velocity distribution is poorly resolved, yet it is crucial that gross conservation properties be respected in hydro-<span class="hlt">transport</span> applications, such as in the LASNEX code. Some points are raised concerning spatial differencing and time integration.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/13664677','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/13664677"><span id="translatedtitle">An <span class="hlt">electron</span> microscopic study of the intestinal villus. II. The pathway of fat <span class="hlt">absorption</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>PALAY, S L; KARLIN, L J</p> <p>1959-05-25</p> <p>The intestinal pathway for absorbed fat was traced in thin sections of intestinal villi from rats fed corn oil by stomach tube after a fast of 24 to 40 hours. For <span class="hlt">electron</span> microscopy the tissues were fixed in chilled buffered osmium tetroxide and embedded in methacrylate. For light microscopy, other specimens from the same animals were fixed in formal-calcium, mordanted in K(2)Cr(2)O(7), and embedded in gelatin. Frozen sections were stained with Sudan black B or Sudan IV. About 20 minutes after feeding, small fat droplets (65 mmicro maximal diameter) appear in the striated border between microvilli. At the same time fat particles are seen within pinocytotic vesicles in the immediately subjacent terminal web. In later specimens the fat droplets are generally larger (50 to 240 mmicro) and lie deeper in the apical cytoplasm. All intracellular fat droplets are loosely enveloped in a thin membrane, the outer surface of which is sometimes studded with the fine particulate component of the cytoplasm. This envelope, apparently derived from the cell surface by pinocytosis, has at this stage evidently become a part of the endoplasmic reticulum. Just above the nucleus numerous fat droplets lie clustered within the dilated cisternae of the Golgi complex. As <span class="hlt">absorption</span> progresses fat droplets appear in the intercellular spaces of the epithelium, in the interstitial connective tissue spaces of the lamina propria, and in the lumen of the lacteals. All of these extracellular fat droplets are devoid of a membranous envelope. The picture of fat <span class="hlt">absorption</span> as reconstructed from these studies involves a stream of fat droplets filtering through the striated border, entering the epithelial cell by pinocytosis at the bases of the intermicrovillous spaces, and coursing through the endoplasmic reticulum to be discharged at the sides of the epithelial cell into extracellular spaces. From the epithelial spaces, the droplets move into the lamina propria and thence into the lymph. If the lumen</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/971443','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/971443"><span id="translatedtitle">Electrokinesis is a microbial behavior that requires extracellular <span class="hlt">electron</span> <span class="hlt">transport</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Harris, Howard W.; El-Naggar, Mohamed Y.; Bretschger, Orianna; Ward, Melissa J.; Romine, Margaret F.; Obraztsova, Anna; Nealson, Kenneth H.</p> <p>2010-01-05</p> <p>Shewanella species are widespread in nature, enjoying a cosmopolitan distribution in marine,freshwater, sedimentary and soil environments (1), and have attracted considerable attention in recent years because of their ability to reduce an extensive number of different <span class="hlt">electron</span> 3 acceptors, including the solid (oxy)hydroxides of iron and manganese, such as Fe(OH)3 and MnO2, using one or more proposed mechanisms of extracellular <span class="hlt">electron</span> <span class="hlt">transport</span> (EET) (2, 3). The EET ability of Shewanella species is consistent with their ability to generate electric current in microbial fuel cells in the absence of exogenous <span class="hlt">electron</span> shuttles (4). Various strategies of extracellular <span class="hlt">electron</span> transfer have been proposed in metal-reducing microbes, including naturally-occurring (2) or biogenic (5-7) soluble mediators that ‘shuttle’ <span class="hlt">electrons</span> from cells to acceptors, as well as direct transfer using multiheme cytochromes located on the cell exterior (8) and transfer via conductive nanowires (9-11). S. oneidensis MR-1 features several proteins that are involved with the <span class="hlt">transport</span> of <span class="hlt">electrons</span> to the exterior of the cell where they play an important role with regard to the reduction of solid <span class="hlt">electron</span> acceptors such as metal oxides. These include two outer-membrane decaheme c-type cytochromes (MtrC and OmcA), a membrane spanning protein (MtrB), and two periplasmic multi-heme c-type cytochromes (MtrA and CymA). Deletion of the genes encoding any of these proteins leads to phenotypes that are greatly inhibited with regard to metal-oxide reduction and current production in microbial fuel cells (MFCs) (12, 13). The mutation of genes that code for proteins involved in the movement of cytochromes to the outer membrane also results in loss of metal-reducing phenotypes (13). The shewanellae are highly motile, by virtue of a single polar flagellum, and individual S. oneidensis MR-1 cells have been tracked swimming at speeds of up to, and sometimes over, 100 μm/sec, although the average</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016PhDT.........6B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016PhDT.........6B"><span id="translatedtitle">Nanoscale <span class="hlt">transport</span> of <span class="hlt">electrons</span> and ions in water</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Boynton, Paul Christopher</p> <p></p> <p>The following dissertation discusses the theoretical study of water on the nanoscale, often involved with essential biological molecules such as DNA and proteins. First I introduce the study of water on the nanoscale and how experimentalists approach confinement with nanopores and nanogaps. Then I discuss the theoretical method we choose for understanding this important biological medium on the molecular level, namely classical molecular dynamics. This leads into <span class="hlt">transport</span> mechanisms that utilize water on the nanoscale, in our case <span class="hlt">electronic</span> and ionic <span class="hlt">transport</span>. On the scale of mere nanometers or less <span class="hlt">electronic</span> <span class="hlt">transport</span> in water enters the tunneling regime, requiring the use of a quantum treatment. In addition, I discuss the importance of water in ionic <span class="hlt">transport</span> and its known effects on biological phenomena such as ion selectivity. Water also has great influence over DNA and proteins, which are both introduced in the context of nanopore sequencing. Several techniques for nanopore sequencing are examined and the importance of protein sequencing is explained. In Chapter 2, we study the effect of volumetric constraints on the structure and <span class="hlt">electronic</span> <span class="hlt">transport</span> properties of distilled water in a nanopore with embedded electrodes. Combining classical molecular dynamics simulations with quantum scattering theory, we show that the structural motifs water assumes inside the pore can be probed directly by tunneling. In Chapter 3, we propose an improvement to the original sequencing by tunneling method, in which N pairs of electrodes are built in series along a synthetic nanochannel. Each current time series for each nucleobase is cross-correlated together, reducing noise in the signals. We show using random sampling of data from classical molecular dynamics, that indeed the sequencing error is significantly reduced as the number of pairs of electrodes, N, increases. In Chapter 4, we propose a new technique for de novo protein sequencing that involves translocating a</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3986668','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3986668"><span id="translatedtitle">Inverted organic photovoltaic device with a new <span class="hlt">electron</span> <span class="hlt">transport</span> layer</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p></p> <p>2014-01-01</p> <p>We demonstrate that there is a new solution-processed <span class="hlt">electron</span> <span class="hlt">transport</span> layer, lithium-doped zinc oxide (LZO), with high-performance inverted organic photovoltaic device. The device exhibits a fill factor of 68.58%, an open circuit voltage of 0.86 V, a short-circuit current density of −9.35 cm/mA2 along with 5.49% power conversion efficiency. In addition, we studied the performance of blend ratio dependence on inverted organic photovoltaics. Our device also demonstrates a long stability shelf life over 4 weeks in air. PMID:24674457</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016APS..MARX23001T&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016APS..MARX23001T&link_type=ABSTRACT"><span id="translatedtitle">Thermal and <span class="hlt">Electronic</span> <span class="hlt">Transport</span> in Inorganic and Organic Thermoelectric Materials</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tian, Zhiting</p> <p></p> <p>In this talk, we will first talk about first-principles calculations of phonon and <span class="hlt">electron</span> <span class="hlt">transport</span> in inorganic thermoelectric materials. We will start with rocksalt PbTe and PbSe, and move on to wurtzite ZnO. We will emphasize the strategies to reduce the lattice thermal conductivity. Then we apply first-principles calculations to organic thermoelectric materials. The thermoelectric properties of doped polypyrrole (PPy) will be discussed. In addition, we will cover the chain confinement effects observed in amorphous polymer thin films using molecular dynamics simulations, which highlights the fundamental difference in heat conduction between crystalline polymers and amorphous polymers</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3896775','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3896775"><span id="translatedtitle">Orthogonally modulated molecular <span class="hlt">transport</span> junctions for resettable <span class="hlt">electronic</span> logic gates</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Meng, Fanben; Hervault, Yves-Marie; Shao, Qi; Hu, Benhui; Norel, Lucie; Rigaut, Stéphane; Chen, Xiaodong</p> <p>2014-01-01</p> <p>Individual molecules have been demonstrated to exhibit promising applications as functional components in the fabrication of computing nanocircuits. Based on their advantage in chemical tailorability, many molecular devices with advanced <span class="hlt">electronic</span> functions have been developed, which can be further modulated by the introduction of external stimuli. Here, orthogonally modulated molecular <span class="hlt">transport</span> junctions are achieved via chemically fabricated nanogaps functionalized with dithienylethene units bearing organometallic ruthenium fragments. The addressable and stepwise control of molecular isomerization can be repeatedly and reversibly completed with a judicious use of the orthogonal optical and electrochemical stimuli to reach the controllable switching of conductivity between two distinct states. These photo-/electro-cooperative nanodevices can be applied as resettable <span class="hlt">electronic</span> logic gates for Boolean computing, such as a two-input OR and a three-input AND-OR. The proof-of-concept of such logic gates demonstrates the possibility to develop multifunctional molecular devices by rational chemical design. PMID:24394717</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016PhyE...76...12F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016PhyE...76...12F"><span id="translatedtitle">Time dependent <span class="hlt">electronic</span> <span class="hlt">transport</span> in chiral edge channels</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fève, G.; Berroir, J.-M.; Plaçais, B.</p> <p>2016-02-01</p> <p>We study time dependent <span class="hlt">electronic</span> <span class="hlt">transport</span> along the chiral edge channels of the quantum Hall regime, focusing on the role of Coulomb interaction. In the low frequency regime, the a.c. conductance can be derived from a lumped element description of the circuit. At higher frequencies, the propagation equations of the Coulomb coupled edge channels need to be solved. As a consequence of the interchannel coupling, a charge pulse emitted in a given channel fractionalized in several pulses. In particular, Coulomb interaction between channels leads to the fractionalization of a charge pulse emitted in a given channel in several pulses. We finally study how the Coulomb interaction, and in particular the fractionalization process, affects the propagation of a single <span class="hlt">electron</span> in the circuit. All the above-mentioned topics are illustrated by experimental realizations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016PhyE...82..129F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016PhyE...82..129F"><span id="translatedtitle">Reprint of : Time dependent <span class="hlt">electronic</span> <span class="hlt">transport</span> in chiral edge channels</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fève, G.; Berroir, J.-M.; Plaçais, B.</p> <p>2016-08-01</p> <p>We study time dependent <span class="hlt">electronic</span> <span class="hlt">transport</span> along the chiral edge channels of the quantum Hall regime, focusing on the role of Coulomb interaction. In the low frequency regime, the a.c. conductance can be derived from a lumped element description of the circuit. At higher frequencies, the propagation equations of the Coulomb coupled edge channels need to be solved. As a consequence of the interchannel coupling, a charge pulse emitted in a given channel fractionalized in several pulses. In particular, Coulomb interaction between channels leads to the fractionalization of a charge pulse emitted in a given channel in several pulses. We finally study how the Coulomb interaction, and in particular the fractionalization process, affects the propagation of a single <span class="hlt">electron</span> in the circuit. All the above-mentioned topics are illustrated by experimental realizations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016SeScT..31f5012Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016SeScT..31f5012Y"><span id="translatedtitle">Analytical band Monte Carlo analysis of <span class="hlt">electron</span> <span class="hlt">transport</span> in silicene</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yeoh, K. H.; Ong, D. S.; Ooi, C. H. Raymond; Yong, T. K.; Lim, S. K.</p> <p>2016-06-01</p> <p>An analytical band Monte Carlo (AMC) with linear energy band dispersion has been developed to study the <span class="hlt">electron</span> <span class="hlt">transport</span> in suspended silicene and silicene on aluminium oxide (Al2O3) substrate. We have calibrated our model against the full band Monte Carlo (FMC) results by matching the velocity-field curve. Using this model, we discover that the collective effects of charge impurity scattering and surface optical phonon scattering can degrade the <span class="hlt">electron</span> mobility down to about 400 cm2 V-1 s-1 and thereafter it is less sensitive to the changes of charge impurity in the substrate and surface optical phonon. We also found that further reduction of mobility to ˜100 cm2 V-1 s-1 as experimentally demonstrated by Tao et al (2015 Nat. Nanotechnol. 10 227) can only be explained by the renormalization of Fermi velocity due to interaction with Al2O3 substrate.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2006JPhy4.133..405K&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2006JPhy4.133..405K&link_type=ABSTRACT"><span id="translatedtitle">Behaviour of fast <span class="hlt">electron</span> <span class="hlt">transport</span> in solid targets</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Koenig, M.; Baton, S. D.; Benuzzi-Mounaix, A.; Fuchs, J.; Loupias, B.; Guillou, P.; Batani, D.; Morace, A.; Piazza, D.; Kodama, R.; Norimatsu, T.; Nakatsutsumi, M.; Aglitskiy, Y.; Rousseaux, C.</p> <p>2006-06-01</p> <p>One of the main issues of the fast ignitor scheme is the role of fast <span class="hlt">electron</span> <span class="hlt">transport</span> in the solid fuel heating. Recent experiments used a new target scheme based on the use of cone to guide the PW laser and enhance the <span class="hlt">electron</span> production. In this context it is fundamental to understand the physics underlying this new target scheme. We report here recent and preliminary results of ultra-intense laser pulse interaction with three layer targets in presence of the cone or without. Experiments have been performed at LULI with the 100 TW laser facility, at intensities up to 3 1019 W/cm2. Several diagnostics have been implemented (2D Kα imaging, Kα spectroscopy and rear side imaging, protons emission) to quantify the cone effect.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25307017','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25307017"><span id="translatedtitle">Semiconducting black phosphorus: synthesis, <span class="hlt">transport</span> properties and <span class="hlt">electronic</span> applications.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Liu, Han; Du, Yuchen; Deng, Yexin; Ye, Peide D</p> <p>2015-05-01</p> <p>Phosphorus is one of the most abundant elements preserved in earth, and it comprises a fraction of ∼0.1% of the earth crust. In general, phosphorus has several allotropes, and the two most commonly seen allotropes, i.e. white and red phosphorus, are widely used in explosives and safety matches. In addition, black phosphorus, though rarely mentioned, is a layered semiconductor and has great potential in optical and <span class="hlt">electronic</span> applications. Remarkably, this layered material can be reduced to one single atomic layer in the vertical direction owing to the van der Waals structure, and is known as phosphorene, in which the physical properties can be tremendously different from its bulk counterpart. In this review article, we trace back to the research history on black phosphorus of over 100 years from the synthesis to material properties, and extend the topic from black phosphorus to phosphorene. The physical and <span class="hlt">transport</span> properties are highlighted for further applications in <span class="hlt">electronic</span> and optoelectronics devices.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JPhCS.717a2043O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JPhCS.717a2043O"><span id="translatedtitle"><span class="hlt">Electron</span> <span class="hlt">transport</span> estimated from <span class="hlt">electron</span> spectra using <span class="hlt">electron</span> spectrometer in LFEX laser target experiments</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ozaki, T.; Hata, M.; Matsuo, K.; Kojima, S.; Arikawa, Y.; Fujioka, S.; Sakagami, H.; Sunahara, A.; Nagatomo, H.; Johzaki, T.; Yogo, A.; Morace, A.; Zhang, Z.; Shiraga, H.; Sakata, S.; Nagai, T.; Abe, Y.; Lee, S.; Nakai, M.; Nishimura, H.; Azechi, H.; FIREX Group; GXII-LFEX Group</p> <p>2016-05-01</p> <p>Hot <span class="hlt">electrons</span> which are generated from targets irradiated by a high-intense laser are measured by two <span class="hlt">electron</span> spectrometers (ESMs). However, total <span class="hlt">electron</span> energy observed by the ESM is only less than 1%. Hot <span class="hlt">electrons</span> are confined by self-fields due to the huge current. When an external magnetic field of several hundred Tesla is applied during the laser irradiation on targets, the ESM signals always increase. In the simulation, the same result can be obtained. The reason is that the Alfvén limit can be mitigated due to the external longitudinal magnetic field.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2000JChPh.11310703K&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2000JChPh.11310703K&link_type=ABSTRACT"><span id="translatedtitle">Refractory metals in molten salts: Theory and simulation of geometry, <span class="hlt">electronic</span> structure, and <span class="hlt">electron</span> <span class="hlt">transport</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Koslowski, Thorsten</p> <p>2000-12-01</p> <p>In this work, we present a theoretical and numerical study of the microscopic and <span class="hlt">electronic</span> structure of solutions of refractory metal halides in alkali halide melts, [NbCl5]x[KCl]1-x and [TaCl5]x[KCl]1-x with 0⩽x⩽0.5. The geometry of the melts is described by ensembles of charged hard spheres, the <span class="hlt">electronic</span> structure is modeled by a tight-binding Hamiltonian, which is extended by a reaction field to describe the diabatic energy profile of the <span class="hlt">electronic</span> self-exchange in many-orbital mixed-valence systems. Despite its simplicity, the model leads to the formation of distorted octahedral [NbCl6]- and [TaCl6]- clusters, as evident both from the inspection of the simulation geometries and from the analysis of the partial pair distribution functions. Even in the presence of the strong potential energy fluctuations characteristic of ionic liquids, the octahedral structure is manifest in the density of states in a t2g-eg splitting of the conduction band. The Hamiltonian that describes mixed-valence systems is solved self-consistently. Using an attractive Hubbard parameter of 1.5 eV, we show that the numerical results can be interpreted by Marcus' theory of outer-sphere <span class="hlt">electron</span> transfer reactions with a reorganization energy of 2.2 eV, an <span class="hlt">electronic</span> coupling parameter of 0.12 eV, and an activation energy of 0.42 eV. Both anion-d metal cation and intervalence charge transfer excitations contribute to the optical <span class="hlt">absorption</span> spectrum, the latter leads to a pronounced polaron <span class="hlt">absorption</span> peak. These findings are compared to recent experimental results.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008PCM....35..535P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008PCM....35..535P"><span id="translatedtitle">Thermoluminescence, <span class="hlt">electron</span> paramagnetic resonance and optical <span class="hlt">absorption</span> in natural and synthetic rhodonite crystals</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Paião, J. R. B.; Watanabe, S.</p> <p>2008-10-01</p> <p>Thermoluminescence, <span class="hlt">electron</span> paramagnetic resonance and optical <span class="hlt">absorption</span> properties of rhodonite, a natural silicate mineral, have been investigated and compared to those of synthetic crystal, pure and doped. The TL peaks grow linearly for radiation dose up to 4 kGy, and then saturate. In all the synthetic samples, 140 and 340°C TL peaks are observed; the difference occurs in their relative intensities, but only 340°C peak grows strongly for high doses. Al2O3 and Al2O3 + CaO-doped synthetic samples presented several decades intenser TL compared to that of synthetic samples doped with other impurities. A heating rate of 4°C/s has been used in all the TL readings. The EPR spectrum of natural rhodonite mineral has only one huge signal around g = 2.0 with width extending from 1,000 to 6,000 G. This is due to Mn dipolar interaction, a fact proved by numerical calculation based on Van Vleck dipolar broadening expression. The optical <span class="hlt">absorption</span> spectrum is rich in <span class="hlt">absorption</span> bands in near-UV, visible and near-IR intervals. Several bands in the region from 540 to 340 nm are interpreted as being due to Mn3+ in distorted octahedral environment. A broad and intense band around 1,040 nm is due to Fe2+. It decays under heating up to 900°C. At this temperature it is reduced by 80% of its original intensity. The pink, natural rhodonite, heated in air starts becoming black at approximately 600°C.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active"><span>17</span></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_17 --> <div id="page_18" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="341"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1993PhDT........97G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1993PhDT........97G"><span id="translatedtitle">Long-Range Superexchange in <span class="hlt">Electron</span> <span class="hlt">Transport</span> Proteins</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gruschus, James Michael</p> <p></p> <p> cytochrome c, as well as plastocyanin, cytochrome b _5, and cytochrome c peroxidase. The surfaces reveal important clues as to which conformations of the <span class="hlt">electron</span> <span class="hlt">transport</span> protein complexes actually give rise to <span class="hlt">electron</span> transfer, a subject of broad biological interest.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/6202181','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/6202181"><span id="translatedtitle"><span class="hlt">Electron</span> heat <span class="hlt">transport</span> in a steep temperature gradient</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Rogers, J.H.; De Groot, J.S.; Abou-Assaleh, Z.; Matte, J.P.; Johnston, T.W.; Rosen, M.D.</p> <p>1989-04-01</p> <p>Temporal and spatial measurements of <span class="hlt">electron</span> heat <span class="hlt">transport</span> are made in the University of California Davis AURORA device (J. H. Rogers, Ph.D. dissertation, University of California, Davis, 1987). In AURORA, a microwave pulse heats a region of underdense, collisional, plasma (n/n/sub cr/ approx. <1, where n/sub cr/ = 1.8 x 10/sup 10/ cm/sup -3/ is the critical density, T/sub e//sub 0/ approx. =0.15 eV, and the <span class="hlt">electron</span> scattering mean free path lambda/sub perpendicular/approx. >2 cm). In this region, strong thermal heating (T/sub c/ approx. <0.7 eV) as well as suprathermal heating (T/sub h/approx. =3 eV) is observed. The strong heating results in a steep temperature gradient that violates the approximations of classical heat diffusion theory (L/sub T//lambda/sub perpendicular/approx. >3 for thermal <span class="hlt">electrons</span>, where L/sub T/ = T/sub c/(partialT/sub c//partialz)/sup -1/ is the cold <span class="hlt">electron</span> temperature scale length. The time evolution of the <span class="hlt">electron</span> temperature profile is measured using Langmuir probes. The measured relaxation of the temperature gradient after the microwave pulse is compared to calculations using the Fokker--Planck International code (Phys. Rev. Lett. 49, 1936 (1982)) and the multigroup, flux-limited, target design code LASNEX (Comm. Plasma Phys. 2, 51 (1975)). The <span class="hlt">electron</span> distribution function at the end of the microwave pulse is used as initial conditions for both codes. The Fokker--Planck calculations are found to agree very well with the measurements.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AIPC.1767b0023V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AIPC.1767b0023V"><span id="translatedtitle"><span class="hlt">Electronic</span> <span class="hlt">absorption</span> spectra of rare earth (III) species in NaCl-2CsCl eutectic based melts</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Volkovich, V. A.; Ivanov, A. B.; Yakimov, S. M.; Tsarevskii, D. V.; Golovanova, O. A.; Sukhikh, V. V.; Griffiths, T. R.</p> <p>2016-09-01</p> <p><span class="hlt">Electronic</span> <span class="hlt">absorption</span> spectra of ions of trivalent rare earth elements were measured in the melts based on NaCl-2CsCl eutectic in the wavelength ranges of 190-1350 and 1450-1700 nm. The measurements were performed at 550-850 °C. The EAS of Y, La, Ce and Lu containing melts have no <span class="hlt">absorption</span> bands in the studied regions. For the remaining REEs (Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb) the <span class="hlt">absorption</span> bands in the EAS were assigned to the corresponding f-f <span class="hlt">electron</span> transitions. The Stark effect was observed for Yb(III) F5/2 excited state. Increasing temperature leads to decreasing intensity of the <span class="hlt">absorption</span> bands, except for the bands resulting from hypersensitive transitions. Beer's law was confirmed up to 0.4 M solutions of REE.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/21537844','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/21537844"><span id="translatedtitle">Efficient laser <span class="hlt">absorption</span> and enhanced <span class="hlt">electron</span> yield in the laser-target interaction by using a cone-nanolayer target</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Cao Lihua; Cai Hongbao; Chen Mo; Wu Sizhong; Zhao Zongqing; Gu Yuqiu; Yu Wei; Yu, M. Y.; He, X. T.</p> <p>2011-05-15</p> <p>A cone-nanolayer target that combines the advantages of the conical and layered geometries for <span class="hlt">electron</span> acceleration in laser-target interaction is proposed. Two-dimensional particle-in-cell (PIC) simulations show that the cone-nanolayer target can enhance laser <span class="hlt">absorption</span> and <span class="hlt">electron</span> yield. With suitable choice of the laser and target parameters, the cone-nanolayer target can be a controllable source of hot <span class="hlt">electrons</span> at desired energy ranges.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/763897','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/763897"><span id="translatedtitle">Interfacial Charge <span class="hlt">Transport</span> in Organic <span class="hlt">Electronic</span> Materials: the Key to a New <span class="hlt">Electronics</span> Technology</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Smith, D.L.; Campbell, I.H.; Davids, P.S.; Heller, C.M.; Laurich, B.K.; Crone, B.K.; Saxena, A.; Bishop, A.R.; Ferraris, J.P.; Yu, Z.G.</p> <p>1999-06-04</p> <p>This is the final report of a three-year, Laboratory Directed Research and Development (LDRD) project at Los Alamos National Laboratory (LANL). The primary aim of this project is to obtain a basic scientific understanding of electrical <span class="hlt">transport</span> processes at interfaces that contain an organic <span class="hlt">electronic</span> material. Because of their processing advantages and the tunability of their <span class="hlt">electronic</span> properties, organic <span class="hlt">electronic</span> materials are revolutionizing major technological areas such as information display. We completed an investigation of the fundamental <span class="hlt">electronic</span> excitation energies in the prototype conjugated polymer MEH-PPV. We completed a combined theoretical/experimental study of the energy relation between charged excitations in a conjugated polymer and the metal at a polymer/metal interface. We developed a theoretical model that explains injection currents at polymer/metal interfaces. We have made electrical measurements on devices fabricated using the conjugated polymer MEH-PPV a nd a series of metals.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016APS..MARS29010B&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016APS..MARS29010B&link_type=ABSTRACT"><span id="translatedtitle">Change In The <span class="hlt">Electronic</span> Structure And Optical <span class="hlt">Absorption</span> Of Cuprate Delafossites Via B-site Alloying</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Beesley, Ramon; Panapitiya, Gihan; Lewis, James; Lewis Group Team</p> <p></p> <p>Delafossite oxides are a family of materials with the form ABO2 , where the A-site is a monovalent cation (Cu , Ag , Au) and the B-site is a trivalent cation (Ga , Al , In). Delafossites typically have a wide optical band gap, this band gap may be tuned by adding a second B-site element forming an AB(1- x) 1B(x)2O2 alloy. We investigate changes in the <span class="hlt">electronic</span> structure of CuAlO2 , CuGaO2 , and CuInO2 when alloyed with CuFeO2 . Using the FIREBALL program to optimize the atomic structure, calculate the total and partial density of states, calculate the valence band edge for each alloy level, and investigate the clustering factor of the second B-site atom, it is found that alloying with Fe creates midgap states caused by Fe - O interactions. From the partial density of state, each type of atoms contribution to the change in the valence band edge can be seen. Observed changes to the materials include increased optical <span class="hlt">absorption</span> in the visible range, and symmetry breaking because of the deformation in the crystal structure. The CuFeO2 alloying percentages range from 0-5%. We are synthesizing these alloys to experimentally verify the changes in the optical <span class="hlt">absorption</span> spectra.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1213049','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1213049"><span id="translatedtitle">Attosecond transient <span class="hlt">absorption</span> probing of <span class="hlt">electronic</span> superpositions of bound states in neon. Detection of quantum beats</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Beck, Annelise R; Bernhardt, Birgitta; Warrick, Erika R.; Wu, Mengxi; Chen, Shaohao; Gaarde, Mette B.; Schafer, Kenneth J.; Neumark, Daniel M.; Leone, Stephen R.</p> <p>2014-11-07</p> <p><span class="hlt">Electronic</span> wavepackets composed of multiple bound excited states of atomic neon lying between 19.6 and 21.5 eV are launched using an isolated attosecond pulse. Individual quantum beats of the wavepacket are detected by perturbing the induced polarization of the medium with a time-delayed few-femtosecond near-infrared (NIR) pulse via coupling the individual states to multiple neighboring levels. All of the initially excited states are monitored simultaneously in the attosecond transient <span class="hlt">absorption</span> spectrum, revealing Lorentzian to Fano lineshape spectral changes as well as quantum beats. The most prominent beating of the several that were observed was in the spin–orbit split 3d <span class="hlt">absorption</span> features, which has a 40 femtosecond period that corresponds to the spin–orbit splitting of 0.1 eV. The few-level models and multilevel calculations confirm that the observed magnitude of oscillation depends strongly on the spectral bandwidth and tuning of the NIR pulse and on the location of possible coupling states.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/385634','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/385634"><span id="translatedtitle">High resolution <span class="hlt">electron</span> energy loss spectroscopy: A new probe of subgap <span class="hlt">absorption</span> in amorphous solids</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Lopinski, G.P.; Lannin, J.S.</p> <p>1996-10-01</p> <p>The use of high resolution <span class="hlt">electron</span> energy spectroscopy (HREELS) as a new method for studies of subgap <span class="hlt">absorption</span> in thin films of amorphous semiconductors is demonstrated. For a-Si films, the {alpha}({omega}) values extracted from the measured loss spectra are in quantitative agreement with previous optical measurements. The method is also applied to both threefold and diamond-like amorphous carbon films, yielding {alpha}({omega}) down to considerably lower energies ({approximately}50 meV) than previously reported. The HREELS method is shown to be complementary to existing techniques in that it can access the regime of low energies and ultrathin films which is difficult to investigate with the conventional methods. {copyright} {ital 1996 American Institute of Physics.}</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015APS..DPPGO6011W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015APS..DPPGO6011W"><span id="translatedtitle">Saturable <span class="hlt">Absorption</span> of an X-Ray Free-<span class="hlt">Electron</span>-Laser Heated Solid-Density Plasma</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wark, J. S.; Rackstraw, D. S.; Ciricosta, O.; Vinko, S. M.; Burian, T.; Chalupsky, J.; Hajkova, V.; Juha, L.; Barbrel, B.; Engelhorn, K.; Cho, B.-I.; Chung, H.-K.; Dakovski, G.; Krzywinski, J.; Heimann, P.; Holmes, M.; Turner, J.; Lee, R. W.; Toleikis, S.; Zastrau, U.</p> <p>2015-11-01</p> <p>High-intensity ~1017 Wcm-2, short duration (100 fsec) x-ray pulses from the LCLS x-ray free-<span class="hlt">electron</span> laser, with photon energies ranging from below to above the K-edge of cold Al (1560 eV), are used to generate and probe a solid-density aluminum plasma. The photon-energy-dependent transmission of the heating beam is studied through the use of a photodiode. Saturable <span class="hlt">absorption</span> is observed, with the resulting transmission differing significantly from the cold case, with the increased transmission being due to the K-edge energy of the dominant ion species shifting in time as the solid-density target is heated, in good agreement with atomic-kinetics simulations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/27176968','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/27176968"><span id="translatedtitle">Selective two-photon <span class="hlt">absorptive</span> resonance femtosecond-laser <span class="hlt">electronic</span>-excitation tagging velocimetry.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Jiang, Naibo; Halls, Benjamin R; Stauffer, Hans U; Danehy, Paul M; Gord, James R; Roy, Sukesh</p> <p>2016-05-15</p> <p>Selective two-photon <span class="hlt">absorptive</span> resonance femtosecond-laser <span class="hlt">electronic</span>-excitation tagging (STARFLEET), a nonseeded ultrafast-laser-based velocimetry technique, is demonstrated in reactive and nonreactive flows. STARFLEET is pumped via a two-photon resonance in N<sub>2</sub> using 202.25 nm 100 fs light. STARFLEET greatly reduces the per-pulse energy required (30 μJ/pulse) to generate the signature FLEET emission compared to the conventional FLEET technique (1.1 mJ/pulse). This reduction in laser energy results in less energy deposited in the flow, which allows for reduced flow perturbations (reactive and nonreactive), increased thermometric accuracy, and less severe damage to materials. Velocity measurements conducted in a free jet of N<sub>2</sub> and in a premixed flame show good agreement with theoretical velocities, and further demonstrate the significantly less intrusive nature of STARFLEET. PMID:27176968</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JQSRT.182..286L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JQSRT.182..286L"><span id="translatedtitle">Excited <span class="hlt">electronic</span> structure of methylcyanoacetylene probed by VUV Fourier-transform <span class="hlt">absorption</span> spectroscopy</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lamarre, N.; Gans, B.; Vieira Mendes, L. A.; Gronowski, M.; Guillemin, J.-C.; De Oliveira, N.; Douin, S.; Chevalier, M.; Crépin, C.; Kołos, R.; Boyé-Péronne, S.</p> <p>2016-10-01</p> <p>High resolution photoabsorption spectrum of gas-phase methylcyanoacetylene (CH3C3 N) has been recorded from 44 500 to 130 000 cm-1 at room temperature with a vacuum ultraviolet Fourier-transform spectrometer on the DESIRS synchrotron beamline (SOLEIL). The absolute photoabsorption cross section in this range is reported for the first time. Valence shell transitions and Rydberg series converging to the ground state X˜+2E of the cation as well as series converging to <span class="hlt">electronically</span> excited states (A˜+A21 and C˜+) are observed and assigned. Time-dependent density-functional-theory calculations have been performed to support the assignment of the experimental spectrum in the low energy range. A tentative scaling of the previously measured CH3C3N+ ion yield by Lamarre et al. [17] is proposed, based on the comparison of the <span class="hlt">absorption</span> data above the first ionization potential with the observed autoionization structures.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21861507','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21861507"><span id="translatedtitle"><span class="hlt">Electronic</span> <span class="hlt">absorption</span> spectra of protonated pyrene and coronene in neon matrixes.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Garkusha, Iryna; Fulara, Jan; Sarre, Peter J; Maier, John P</p> <p>2011-10-13</p> <p>Protonated pyrene and coronene have been isolated in 6 K neon matrixes. The cations were produced in the reaction of the parent aromatics with protonated ethanol in a hot-cathode discharge source, mass selected, and co-deposited with neon. Three <span class="hlt">electronic</span> transitions of the most stable isomer of protonated pyrene and four of protonated coronene were recorded. The strongest, S(1) ← S(0) transitions, are in the visible region, with onset at 487.5 nm for protonated pyrene and 695.6 nm for protonated coronene. The corresponding neutrals were also observed. The <span class="hlt">absorptions</span> were assigned on the basis of ab initio coupled-cluster and time-dependent density functional theory calculations. The astrophysical relevance of protonated polycyclic aromatic hydrocarbons is discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/20863743','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/20863743"><span id="translatedtitle"><span class="hlt">Electronic</span> <span class="hlt">absorption</span> spectroscopy of polycyclic aromatic hydrocarbons (PAHs) radical cations generated in oleum: a superacid medium.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Cataldo, Franco; Iglesias-Groth, Susana; Manchado, Arturo</p> <p>2010-12-01</p> <p>Oleum (fuming sulphuric acid), a well known superacid, was used as medium for the generation of the radical cation of a series of selected PAHs. The resulting radical cation spectra were studied by <span class="hlt">electronic</span> <span class="hlt">absorption</span> spectroscopy. Not only common PAHs like naphthalene, anthracene, tetracene, pentacene, perylene, pyrene, benzo[a]pyrene, phenanthrene and picene were studied but also the less common and very large PAHs relevant also for the astrochemical research, like coronene, hexabenzocoronene, quaterrylene, dicoronylene and a coronene oligomer. A correlation between the first ionization potential (IP1) of the PAHs studied and the energy to the so-called A-type band of the radical cations observed in oleum has led to the equation IP1=1.30EA+4.39 (in eV) which permits to estimate the energy of the PAHs radical cation transition (EA) in the VIS-NIR knowing the relative ionization potential or vice versa. PMID:20863743</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012PhRvB..86o5406K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012PhRvB..86o5406K"><span id="translatedtitle"><span class="hlt">Electron</span> <span class="hlt">transport</span> through single endohedral Ce@C82 metallofullerenes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kaneko, Satoshi; Wang, Lu; Luo, Guangfu; Lu, Jing; Nagase, Shigeru; Sato, Satoru; Yamada, Michio; Slanina, Zdenek; Akasaka, Takeshi; Kiguchi, Manabu</p> <p>2012-10-01</p> <p>The <span class="hlt">electron</span> <span class="hlt">transport</span> through a single endohedral Ce@C82 metallofullerene bridging between metal electrodes was investigated with experimental (break junction) as well as theoretical (density functional theory coupled with the nonequilibrium Green's function formalism) techniques. The single Ce@C82 molecule junction showing a high and fixed conductance value was fabricated by direct binding of the metallofullerene to Ag electrodes. The junction had a conductance of 0.28(±0.05)G0 (G0 = 2e2/h), which was much larger than that of single molecule junctions having anchoring groups (<0.01G0), but only half that of the single C60 molecule junction of 0.5G0. The unexpected reduced conductance of the single Ce@C82 molecule junction compared with that of the single C60 molecule junction was supported by the ab initio quantum <span class="hlt">transport</span> calculations and was explained in terms of the localization of <span class="hlt">electrons</span> in the C82 cage. In the case of the Au electrodes, the single Ce@C82 molecule junction was not formed by the break junction technique because the Ce@C82 molecule could not be trapped in the large Au nanogap, which was formed just after breaking the Au contacts.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/477761','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/477761"><span id="translatedtitle"><span class="hlt">Electron</span> <span class="hlt">transport</span> in coupled double quantum wells and wires</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Harff, N.E.; Simmons, J.A.; Lyo, S.K.</p> <p>1997-04-01</p> <p>Due to inter-quantum well tunneling, coupled double quantum wells (DQWs) contain an extra degree of <span class="hlt">electronic</span> freedom in the growth direction, giving rise to new <span class="hlt">transport</span> phenomena not found in single <span class="hlt">electron</span> layers. This report describes work done on coupled DQWs subject to inplane magnetic fields B{sub {parallel}}, and is based on the lead author`s doctoral thesis, successfully defended at Oregon State University on March 4, 1997. First, the conductance of closely coupled DQWs in B{sub {parallel}} is studied. B{sub {parallel}}-induced distortions in the dispersion, the density of states, and the Fermi surface are described both theoretically and experimentally, with particular attention paid to the dispersion anticrossing and resulting partial energy gap. Measurements of giant distortions in the effective mass are found to agree with theoretical calculations. Second, the Landau level spectra of coupled DQWs in tilted magnetic fields is studied. The magnetoresistance oscillations show complex beating as Landau levels from the two Fermi surface components cross the Fermi level. A third set of oscillations resulting from magnetic breakdown is observed. A semiclassical calculation of the Landau level spectra is then performed, and shown to agree exceptionally well with the data. Finally, quantum wires and quantum point contacts formed in DQW structures are investigated. Anticrossings of the one-dimensional DQW dispersion curves are predicted to have interesting <span class="hlt">transport</span> effects in these devices. Difficulties in sample fabrication have to date prevented experimental verification. However, recently developed techniques to overcome these difficulties are described.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/787905','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/787905"><span id="translatedtitle">Simulations of <span class="hlt">Electron</span> <span class="hlt">Transport</span> in Laser Hot Spots</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>S. Brunner; E. Valeo</p> <p>2001-08-30</p> <p>Simulations of <span class="hlt">electron</span> <span class="hlt">transport</span> are carried out by solving the Fokker-Planck equation in the diffusive approximation. The system of a single laser hot spot, with open boundary conditions, is systematically studied by performing a scan over a wide range of the two relevant parameters: (1) Ratio of the stopping length over the width of the hot spot. (2) Relative importance of the heating through inverse Bremsstrahlung compared to the thermalization through self-collisions. As for uniform illumination [J.P. Matte et al., Plasma Phys. Controlled Fusion 30 (1988) 1665], the bulk of the velocity distribution functions (VDFs) present a super-Gaussian dependence. However, as a result of spatial <span class="hlt">transport</span>, the tails are observed to be well represented by a Maxwellian. A similar dependence of the distributions is also found for multiple hot spot systems. For its relevance with respect to stimulated Raman scattering, the linear Landau damping of the <span class="hlt">electron</span> plasma wave is estimated for such VD Fs. Finally, the nonlinear Fokker-Planck simulations of the single laser hot spot system are also compared to the results obtained with the linear non-local hydrodynamic approach [A.V. Brantov et al., Phys. Plasmas 5 (1998) 2742], thus providing a quantitative limit to the latter method: The hydrodynamic approach presents more than 10% inaccuracy in the presence of temperature variations of the order delta T/T greater than or equal to 1%, and similar levels of deformation of the Gaussian shape of the Maxwellian background.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012JPCM...24p4209Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012JPCM...24p4209Z"><span id="translatedtitle"><span class="hlt">Electron</span> <span class="hlt">transport</span> properties of single molecular junctions under mechanical modulations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhou, Jianfeng; Guo, Cunlan; Xu, Bingqian</p> <p>2012-04-01</p> <p><span class="hlt">Electron</span> <span class="hlt">transport</span> behaviors of single molecular junctions are very sensitive to the atomic scale molecule-metal electrode contact interfaces, which have been difficult to control. We used a modified scanning probe microscope-break junction technique (SPM-BJT) to control the dynamics of the contacts and simultaneously monitor both the conductance and force. First, by fitting the measured data into a modified multiple tunneling barrier model, the static contact resistances, corresponding to the different contact conformations of single alkanedithiol and alkanediamine molecular junctions, were identified. Second, the changes of contact decay constant were measured under mechanical extensions of the molecular junctions, which helped to classify the different single molecular conductance sets into specific microscopic conformations of the molecule-electrode contacts. Third, by monitoring the changes of force and contact decay constant with the mechanical extensions, the changes of conductance were found to be caused by the changes of contact bond length and by the atomic reorganizations near the contact bond. This study provides a new insight into the understanding of the influences of contact conformations, especially the effect of changes of dynamic contact conformation on <span class="hlt">electron</span> <span class="hlt">transport</span> through single molecular junctions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/1047362','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/1047362"><span id="translatedtitle"><span class="hlt">Electron</span> <span class="hlt">Transport</span> Materials: Synthesis, Properties and Device Performance</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Cosimbescu, Lelia; Wang, Liang; Helm, Monte L.; Polikarpov, Evgueni; Swensen, James S.; Padmaperuma, Asanga B.</p> <p>2012-06-01</p> <p>We report the design, synthesis and characterization, thermal and photophysical properties of two silane based <span class="hlt">electron</span> <span class="hlt">transport</span> materials, dibenzo[b,d]thiophen-2-yltriphenylsilane (Si{phi}87) and (dibenzo[b,d]thiophen-2-yl)diphenylsilane (Si{phi}88) and their performance in blue organic light emitting devices (OLEDs). The utility of these materials in blue OLEDs with iridium (III) bis[(4,6-difluorophenyl)-pyridinato-N,C']picolinate (Firpic) as the phosphorescent emitter was demonstrated. Using the silane Si{phi}87 as the <span class="hlt">electron</span> <span class="hlt">transport</span> material (ETm) an EQE of 18.2% was obtained, with a power efficiency of 24.3 lm/W (5.8V at 1mA/cm{sup 2}), in a heterostructure. When Si{phi}88 is used, the EQE is 18.5% with a power efficiency of 26.0 lm/W (5.5V at 1mA/cm{sup 2}).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/238895','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/238895"><span id="translatedtitle">Studies of fullerene <span class="hlt">absorption</span> and production using an infrared free-<span class="hlt">electron</span> laser</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Affatigato, M.; Haglund, R.F.; Ying, Z.C.; Compton, R.N.</p> <p>1995-12-31</p> <p>Tunable photon sources such as free-<span class="hlt">electron</span> lasers are potentially valuable tools in spectroscopic studies of fullerenes, a new class of carbon materials with unique cage structures. We have used the infrared free-<span class="hlt">electron</span>-laser facility at Vanderbilt University to study the infrared <span class="hlt">absorption</span> of gas-phase fullerene molecules and also to investigate the effects of an infrared laser in the synthesis and crystallization of fullerene materials. In one experiment, fullerene vapor was created in a heat pipe through which the FEL beam was passed; the transmission of the FEL beam relative to a reference detector was measured as a function of wavelength. A large (>10%) <span class="hlt">absorption</span> of the IR laser was observed when it passed through C{sub 60} vapor at {approximately}800{degrees}C. Due to the broad spectral width of the FEL as well as spectral congestion, no spectral peaks were seen when the laser wavelength was tuned across a T{sub 1u}C{sub 60} IR mode near 7.0 {mu}. However, it is expected that the vibrational features can be resolved experimentally by passing the transmitted beam through a monochromator. In a separate experiment, the FEL beam was focused onto a surface of graphite or graphite/metal mixture target. Various fullerene molecules, including endohedral types, were produced when the soot was recovered from the ablation chamber. The yield of the products was measured to be {approximately}0.4 g/J of the incident laser energy. However, both the yield and the product distribution are virtually, the same as those in experiments using a nanosecond Nd:YAG laser. This suggests that the laser wavelength is not a crucial parameter in making fullerenes by laser ablation. Even when the laser is at resonance with one of the vibrational modes of C{sub 60}, the fullerene production is neither substantially enhanced nor suppressed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016APS..DMP.Q1094S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016APS..DMP.Q1094S"><span id="translatedtitle">Computing Rydberg <span class="hlt">Electron</span> <span class="hlt">Transport</span> Rates via Classical Periodic Orbits</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sattari, Sulimon; Mitchell, Kevin</p> <p>2016-05-01</p> <p><span class="hlt">Electron</span> <span class="hlt">transport</span> properties of chaotic atomic systems may be computable from classical periodic orbits. This technique allows for replacing a Monte Carlo simulation launching millions of orbits with a sum over tens or hundreds of properly chosen periodic orbits. A firm grasp of the structure of the periodic orbits is required to obtain accurate <span class="hlt">transport</span> rates. We apply a technique called homotopic lobe dynamics (HLD) to understand the structure of periodic orbits to compute the ionization rate of a hydrogen atom in strong parallel electric and magnetic fields. HLD uses information encoded in the intersections of stable and unstable manifolds of a few orbits to compute all relevant periodic orbits in the system. The ionization rate computed from periodic orbits using HLD converges exponentially to the true value as a function of the highest period used. We then use periodic orbit continuation to accurately compute the ionization rate when the field strengths are varied. The ability to use periodic orbits in a mixed phase space could allow for studying <span class="hlt">transport</span> in even more complex few body systems.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_18 --> <div id="page_19" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="361"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/21120514','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/21120514"><span id="translatedtitle"><span class="hlt">Electron</span> thermal <span class="hlt">transport</span> analysis in Tokamak a Configuration Variable</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Asp, E.; Porte, L.; Alberti, S.; Karpushov, A.; Martin, Y.; Sauter, O.; Turri, G.; Kim, J.-H.; Horton, W.</p> <p>2008-08-15</p> <p>A Tokamak a Configuration Variable (TCV) [G. Tonetti, A. Heym, F. Hofmann et al., in Proceedings of the 16th Symposium on Fusion Technology, London, U.K., edited by R. Hemsworth (North-Holland, Amsterdam, 1991), p. 587] plasma with high power density (up to 8 MW/m{sup 3}) core deposited <span class="hlt">electron</span> cyclotron resonance heating at significant plasma densities ({<=}7x10{sup 19} m{sup -3}) is analyzed for the <span class="hlt">electron</span> thermal <span class="hlt">transport</span>. The discharge distinguishes itself as it has four distinct high confinement mode (H-mode) phases. An Ohmic H-mode with type III edge localized modes (ELMs), which turns into a type I ELMy H-mode when the ECRH is switched on. The ELMs then vanish, which gives rise to a quasistationary ELM-free H-mode. This ELM-free phase can be divided into two, one without magnetohydrodynamics (MHD) and one with. The MHD mode in the latter case causes the confinement to drop by {approx}15%. For all four phases both large-scale trapped <span class="hlt">electron</span> (TEM) and ion temperature gradient (ITG) modes and small-scale <span class="hlt">electron</span> temperature gradient (ETG) modes are analyzed. The analytical TEM formulas have difficulty in explaining both the magnitude and the radial profile of the <span class="hlt">electron</span> thermal flux. Collisionality governs the drive of the TEM, which for the discharge in question implies it can be driven by either the temperature or density gradient. The TEM response function is derived and it is shown to be relatively small and to have sharp resonances in its energy dependence. The ETG turbulence, predicted by the Institute for Fusion Studies <span class="hlt">electron</span> gyrofluid code, is on the other hand driven solely by the <span class="hlt">electron</span> temperature gradient. Both trapped and passing <span class="hlt">electrons</span> add to the ETG instability and turbulent thermal flux. For easy comparison of the results of the above approaches and also with the Weiland model, a dimensionless error measure, the so-called average relative variance is introduced. According to this method the ETG model explains 70% of the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2007PhDT.......202W&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2007PhDT.......202W&link_type=ABSTRACT"><span id="translatedtitle">Spin-dependent <span class="hlt">electron</span> <span class="hlt">transport</span> in nanoscale samples</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wei, Yaguang</p> <p></p> <p>In this thesis, we describe the research in which we use metallic nanoparticles to explore spin-dependent <span class="hlt">electron</span> <span class="hlt">transport</span> at nanometer scale. Nanoscale samples were fabricated by using a state of the art <span class="hlt">electron</span> beam lithography and shadow evaporation technique. We have investigated spin relaxation and decoherence in metallic grains as a function of bias voltage and magnetic field at low temperatures (down to ˜30mK). At low temperatures, the discrete energy levels within a metallic nanoparticle provides a new means to study the physics of the spin-polarized <span class="hlt">electron</span> tunneling. We describe measurements of spin-polarized tunneling via discrete energy levels of single Aluminum grain. Spin polarized current saturates quickly as a function of bias voltage, which demonstrates that the ground state and the lowest excited states carry spin polarized current. The ratio of <span class="hlt">electron</span>-spin relaxation time (T1) to the <span class="hlt">electron</span>-phonon relaxation rate is in quantitative agreement with the Elliot-Yafet scaling, an evidence that spin-relaxation in Al grains is driven by the spin-orbit interaction. The spin-relaxation time of the low-lying excited states is T1 ≈ 0.7 mus and 0.1 mus in two samples, showing that <span class="hlt">electron</span> spin in a metallic grain could be a potential candidate for quantum information research. We also present measurements of mesoscopic resistance fluctuations in cobalt nanoparticles at low temperature and study how the fluctuations with bias voltage, bias fingerprints, respond to magnetization-reversal processes. Bias fingerprints rearrange when domains are nucleated or annihilated. The domain wall causes an <span class="hlt">electron</span> wave function-phase shift of ˜5 pi. The phase shift is not caused by the Aharonov-Bohm effect; we explain how it arises from the mistracking effect, where <span class="hlt">electron</span> spins lag in orientation with respect to the moments inside the domain wall. The dephasing length at low temperatures is only 30 nm, which is attributed to the large magnetocrystalline</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/23385304','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/23385304"><span id="translatedtitle">Nanogap structures: combining enhanced Raman spectroscopy and <span class="hlt">electronic</span> <span class="hlt">transport</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Natelson, Douglas; Li, Yajing; Herzog, Joseph B</p> <p>2013-04-21</p> <p>Surface-enhanced Raman spectroscopy (SERS) is an experimental tool for accessing vibrational and chemical information, down to the single molecule level. SERS typically relies on plasmon excitations in metal nanostructures to concentrate the incident radiation and to provide an enhanced photon density of states to couple emitted radiation to the far field. Many common SERS platforms involve metal nanoparticles to generate the required electromagnetic enhancements. Here we concentrate on an alternative approach, in which the relevant plasmon excitations are supported at a truly nanoscale gap between extended electrodes, rather than discrete subwavelength nanoparticles. The ability to fabricate precise gaps on demand, and in some cases to tune the gap size in situ, combined with the additional capability of simultaneous <span class="hlt">electronic</span> <span class="hlt">transport</span> measurements of the nanogap, provides access to information not previously available in standard SERS. We summarize the rich plasmonic physics at work in these extended systems and highlight the recent state of the art including tip-enhanced Raman spectroscopy (TERS) and the application of mechanical break junctions and electromigrated junctions. We describe in detail how we have performed in situ gap-enhanced Raman measurements of molecular-scale junctions while simultaneously subjecting these structures to <span class="hlt">electronic</span> <span class="hlt">transport</span>. These extended electrode structures allow us to study the pumping of vibrational modes by the flow of tunneling <span class="hlt">electrons</span>, as well as the shifting of vibrational energies due to the applied bias. These experiments extend SERS into a tool for examining fundamental processes of dissipation, and provide insight into the mechanisms behind SERS spectral diffusion. We conclude with a brief discussion of future directions. PMID:23385304</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/18351940','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/18351940"><span id="translatedtitle">Proton acceleration in the electrostatic sheaths of hot <span class="hlt">electrons</span> governed by strongly relativistic laser-<span class="hlt">absorption</span> processes.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ter-Avetisyan, S; Schnürer, M; Sokollik, T; Nickles, P V; Sandner, W; Reiss, H R; Stein, J; Habs, D; Nakamura, T; Mima, K</p> <p>2008-01-01</p> <p>Two different laser energy <span class="hlt">absorption</span> mechanisms at the front side of a laser-irradiated foil have been found to occur, such that two distinct relativistic <span class="hlt">electron</span> beams with different properties are produced. One beam arises from the ponderomotively driven <span class="hlt">electrons</span> propagating in the laser propagation direction, and the other is the result of <span class="hlt">electrons</span> driven by resonance <span class="hlt">absorption</span> normal to the target surface. These properties become evident at the rear surface of the target, where they give rise to two spatially separated sources of ions with distinguishable characteristics when ultrashort (40fs) high-intensity laser pulses irradiate a foil at 45 degrees incidence. The laser pulse intensity and the contrast ratio are crucial. One can establish conditions such that one or the other of the laser energy <span class="hlt">absorption</span> mechanisms is dominant, and thereby one can control the ion acceleration scenarios. The observations are confirmed by particle-in-cell (PIC) simulations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/pages/biblio/1286933-composition-dependence-electronic-magnetic-transport-morphological-properties-mixed-valence-manganite-thin-films','SCIGOV-DOEP'); return false;" href="http://www.osti.gov/pages/biblio/1286933-composition-dependence-electronic-magnetic-transport-morphological-properties-mixed-valence-manganite-thin-films"><span id="translatedtitle">Composition dependence of <span class="hlt">electronic</span>, magnetic, <span class="hlt">transport</span> and morphological properties of mixed valence manganite thin films</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Singh, Surendra; Freeland, J. W.; Fitzsimmons, Michael R.; Jeen, H.; Biswas, A.</p> <p>2016-07-27</p> <p>Mixed-valence manganese oxides present striking properties like the colossal magnetoresistance, metal-insulator transition (MIT) that may result from coexistence of ferromagnetic, metallic and insulating phases. Percolation of such phase coexistence in the vicinity of MIT leads to first-order transition in these manganites. However the length scales over which the <span class="hlt">electronic</span> and magnetic phases are separated across MIT which appears compelling for bulk systems has been elusive in (La1-yPry)1-xCaxMnO3 films. Here we show the in-plane length scale over which charge and magnetism are correlated in (La0.4Pr0.6)1-xCaxMnO3 films with x = 0.33 and 0.375, across the MIT temperature. We combine electrical <span class="hlt">transport</span> (resistance)more » measurements, x-ray <span class="hlt">absorption</span> spectroscopy (XAS), x-ray magnetic circular dichroism (XMCD), and specular/off-specular x-ray resonant magnetic scattering (XRMS) measurements as a function of temperature to elucidate relationships between <span class="hlt">electronic</span>, magnetic and morphological structure of the thin films. Using off-specular XRMS we obtained the charge-charge and charge-magnetic correlation length of these LPCMO films across the MIT. We observed different charge-magnetic correlation length for two films which increases below the MIT. The different correlation length shown by two films may be responsible for different macroscopic (<span class="hlt">transport</span> and magnetic) properties.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012EL.....9935003N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012EL.....9935003N"><span id="translatedtitle"><span class="hlt">Transport</span> of <span class="hlt">electrons</span> in Ar/H2 mixtures</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nikitović, Ž.; Stojanović, V.; Petrović, Z. Lj.</p> <p>2012-08-01</p> <p>In this work we present <span class="hlt">transport</span> coefficients for <span class="hlt">electrons</span> in Ar/H2 mixtures for the conditions used in plasma-assisted technologies for semiconductor production, i.e., in moderate and very high E/N. We used a two-term numerical solution of the Boltzmann equation at the lowest E/N (E is the electric field; N is the gas density) and correspondingly at the lowest mean energies. We also use the Monte Carlo simulation technique at moderate and high E/N. We show that a good agreement with experimental data exists for low and moderate E/N and that based on the tests for pure H2 and Ar we can model properly the swarm properties at high E/N. For the conditions of very high electric fields runaway peaks develop in the <span class="hlt">electron</span> energy distribution function and appreciable contribution of backscattered high-energy <span class="hlt">electrons</span> produces additional emission of Hα emission close to the anode (made of stainless steel). Results are obtained for abundances of H2 from 1% to 30%, which are necessary in kinetic models for this mixture in a number of applications.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2012APS..MARH13012H&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2012APS..MARH13012H&link_type=ABSTRACT"><span id="translatedtitle">Hot <span class="hlt">electron</span> spin <span class="hlt">transport</span> in C60 fullerene</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hueso, Luis Eduardo; Gobbi, Marco; Bedoya-Pinto, Amilcar; Golmar, Federico; Llopis, Roger; Casanova, Felix</p> <p>2012-02-01</p> <p>Carbon-based molecular materials are interesting for spin <span class="hlt">transport</span> application mainly due to their small sources of spin relaxation [1]. However, spin coherence lengths reported in many molecular films do not exceed a few tens of nanometers [2]. In this work we will present results showing how hot spin-polarized <span class="hlt">electrons</span> injected well above the Fermi level in C60 fullerene films travel coherently for hundreds of nanometers. We fabricated hot-<span class="hlt">electron</span> vertical transistors, in which the current created across an Al/Al2O3 junction is polarized by a metallic Co/Cu/Py spin valve trilayer and subsequently injected in the molecular thin film. This geometry allows us to determine the energy level alignment at each interface between different materials. Moreover, the collector magnetocurrent excess 85%, even for C60 films thicknesses of 300 nm. We believe these results show the importance of hot spin-polarized <span class="hlt">electron</span> injection and propagation in molecular materials. [1] V. Dediu, L.E. Hueso, I. Bergenti, C. Taliani, Nature Mater. 8, 707 (2009) [2] M. Gobbi, F. Golmar, R. Llopis, F. Casanova, L.E. Hueso, Adv. Mater. 23, 1609 (2011)</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014PhDT........67Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014PhDT........67Z"><span id="translatedtitle">Tuning The Optical, Charge Injection, and Charge <span class="hlt">Transport</span> Properties of Organic <span class="hlt">Electronic</span> Devices</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zalar, Peter</p> <p></p> <p>Since the early 1900's, synthetic insulating polymers (plastics) have slowly taken over the role that traditional materials like wood or metal have had as basic components for construction, manufactured goods, and parts. Plastics allow for high throughput, low temperature processing, and control of bulk properties through molecular modifications. In the same way, pi-conjugated organic molecules are emerging as a possible substitute for inorganic materials due to their <span class="hlt">electronic</span> properties. The semiconductive nature of pi-conjugated materials make them an attractive candidate to replace inorganic materials, primarily due to their promise for low cost and large-scale production of basic semiconducting devices such as light-emitting diodes, solar cells, and field-effect transistors. Before organic semiconductors can be realized as a commercial product, several hurdles must be cleared. The purpose of this dissertation is to address three distinct properties that dominate the functionality of devices harnessing these materials: (1) optical properties, (2) charge injection, and (3) charge <span class="hlt">transport</span>. First, it is shown that the <span class="hlt">electron</span> injection barrier in the emissive layer of polymer light-emitting diodes can be significantly reduced by processing of novel conjugated oligoelectrolytes or deoxyribonucleic acid atop the emissive layer. Next, the charge <span class="hlt">transport</span> properties of several polymers could be modified by processing them from solvents containing small amounts of additives or by using regioregular and enantiopure chemical structures. It is then demonstrated that the optical and <span class="hlt">electronic</span> properties of Lewis basic polymer structures can be readily modified by interactions with strongly <span class="hlt">electron</span>-withdrawing Lewis acids. Through red-shifted <span class="hlt">absorption</span>, photoluminescence, and electroluminescence, a single pi-conjugated backbone can be polychromatic. In addition, interaction with Lewis acids can remarkably p-dope the hole <span class="hlt">transport</span> of the parent polymer, leading to a</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008PhRvB..77w5102H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008PhRvB..77w5102H"><span id="translatedtitle">Double photoexcitation involving 2p and 4f <span class="hlt">electrons</span> in L3 -edge x-ray <span class="hlt">absorption</span> spectra of protactinium</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hennig, Christoph; Le Naour, Claire; Auwer, Christophe Den</p> <p>2008-06-01</p> <p>The L3 -edge x-ray <span class="hlt">absorption</span> spectrum of Pa(V) fluoride in aqueous solution show clear evidence for the double photoexcitation involving 2p and 4f <span class="hlt">electrons</span>. A comparison with the [2p4f] double-<span class="hlt">electron</span> excitations observed in the L3 -edge x-ray <span class="hlt">absorption</span> spectra of other actinides (thorium, uranium, neptunium, plutonium, and americium) indicates a monotonic increase in the excitation energy. The sharp edgelike structure of the multielectron excitation reveals the origin of a shake-up channel.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016ApJ...826..192D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016ApJ...826..192D"><span id="translatedtitle">Constraint on a Cosmological Variation in the Proton-to-<span class="hlt">electron</span> Mass Ratio from <span class="hlt">Electronic</span> CO <span class="hlt">Absorption</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Daprà, M.; Niu, M. L.; Salumbides, E. J.; Murphy, M. T.; Ubachs, W.</p> <p>2016-08-01</p> <p>Carbon monoxide (CO) <span class="hlt">absorption</span> in the sub-damped Lyα absorber at redshift {z}{abs}≃ 2.69 toward the background quasar SDSS J123714.60+064759.5 (J1237+0647) was investigated for the first time in order to search for a possible variation of the proton-to-<span class="hlt">electron</span> mass ratio, μ, over a cosmological timescale. The observations were performed with the Very Large Telescope/Ultraviolet and Visual Echelle Spectrograph with a signal-to-noise ratio of 40 per 2.5 km s-1 per pixel at ˜5000 Å. Thirteen CO vibrational bands in this absorber are detected: the {{{A}}}1{{\\Pi }} - {{{X}}}1{{{Σ }}}+ (ν \\prime , 0) for ν \\prime =0{--}8, {{{B}}}1{{{Σ }}}+ - {{{X}}}1{{{Σ }}}+ (0, 0), {{{C}}}1{{{Σ }}}+ - {{{X}}}1{{{Σ }}}+ (0, 0), and {{{E}}}1{{\\Pi }} - {{{X}}}1{{{Σ }}}+ (0, 0) singlet-singlet bands and the {d}3{{Δ }} - {{{X}}}1{{{Σ }}}+ (5, 0) singlet-triplet band. An updated database including the most precise molecular inputs needed for a μ-variation analysis is presented for rotational levels J = 0-5, consisting of transition wavelengths, oscillator strengths, natural lifetime damping parameters, and sensitivity coefficients to a variation of the proton-to-<span class="hlt">electron</span> mass ratio. A comprehensive fitting method was used to fit all the CO bands at once and an independent constraint of {{Δ }}μ /μ =(0.7+/- {1.6}{stat}+/- {0.5}{syst})× {10}-5 was derived from CO only. A combined analysis using both molecular hydrogen and CO in the same J1237+0647 absorber returned a final constraint on the relative variation of {{Δ }}μ /μ =(-5.6+/- {5.6}{stat}+/- {3.1}{syst})× {10}-6, which is consistent with no variation over a look-back time of ˜11.4 Gyr.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016ApJ...826..192D&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016ApJ...826..192D&link_type=ABSTRACT"><span id="translatedtitle">Constraint on a Cosmological Variation in the Proton-to-<span class="hlt">electron</span> Mass Ratio from <span class="hlt">Electronic</span> CO <span class="hlt">Absorption</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Daprà, M.; Niu, M. L.; Salumbides, E. J.; Murphy, M. T.; Ubachs, W.</p> <p>2016-08-01</p> <p>Carbon monoxide (CO) <span class="hlt">absorption</span> in the sub-damped Lyα absorber at redshift {z}{abs}≃ 2.69 toward the background quasar SDSS J123714.60+064759.5 (J1237+0647) was investigated for the first time in order to search for a possible variation of the proton-to-<span class="hlt">electron</span> mass ratio, μ, over a cosmological timescale. The observations were performed with the Very Large Telescope/Ultraviolet and Visual Echelle Spectrograph with a signal-to-noise ratio of 40 per 2.5 km s‑1 per pixel at ˜5000 Å. Thirteen CO vibrational bands in this absorber are detected: the {{{A}}}1{{\\Pi }} ‑ {{{X}}}1{{{Σ }}}+ (ν \\prime , 0) for ν \\prime =0{--}8, {{{B}}}1{{{Σ }}}+ ‑ {{{X}}}1{{{Σ }}}+ (0, 0), {{{C}}}1{{{Σ }}}+ ‑ {{{X}}}1{{{Σ }}}+ (0, 0), and {{{E}}}1{{\\Pi }} ‑ {{{X}}}1{{{Σ }}}+ (0, 0) singlet–singlet bands and the {d}3{{Δ }} ‑ {{{X}}}1{{{Σ }}}+ (5, 0) singlet–triplet band. An updated database including the most precise molecular inputs needed for a μ-variation analysis is presented for rotational levels J = 0–5, consisting of transition wavelengths, oscillator strengths, natural lifetime damping parameters, and sensitivity coefficients to a variation of the proton-to-<span class="hlt">electron</span> mass ratio. A comprehensive fitting method was used to fit all the CO bands at once and an independent constraint of {{Δ }}μ /μ =(0.7+/- {1.6}{stat}+/- {0.5}{syst})× {10}-5 was derived from CO only. A combined analysis using both molecular hydrogen and CO in the same J1237+0647 absorber returned a final constraint on the relative variation of {{Δ }}μ /μ =(-5.6+/- {5.6}{stat}+/- {3.1}{syst})× {10}-6, which is consistent with no variation over a look-back time of ˜11.4 Gyr.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/22262617','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22262617"><span id="translatedtitle"><span class="hlt">Electron-electron</span> interaction, weak localization and spin valve effect in vertical-<span class="hlt">transport</span> graphene devices</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Long, Mingsheng; Gong, Youpin; Wei, Xiangfei; Zhu, Chao; Xu, Jianbao; Liu, Ping; Guo, Yufen; Li, Weiwei; Liu, Liwei; Liu, Guangtong</p> <p>2014-04-14</p> <p>We fabricated a vertical structure device, in which graphene is sandwiched between two asymmetric ferromagnetic electrodes. The measurements of <span class="hlt">electron</span> and spin <span class="hlt">transport</span> were performed across the combined channels containing the vertical and horizontal components. The presence of <span class="hlt">electron-electron</span> interaction (EEI) was found not only at low temperatures but also at moderate temperatures up to ∼120 K, and EEI dominates over weak localization (WL) with and without applying magnetic fields perpendicular to the sample plane. Moreover, spin valve effect was observed when magnetic filed is swept at the direction parallel to the sample surface. We attribute the EEI and WL surviving at a relatively high temperature to the effective suppress of phonon scattering in the vertical device structure. The findings open a way for studying quantum correlation at relatively high temperature.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015ApPhL.107o3504B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015ApPhL.107o3504B"><span id="translatedtitle">Density-dependent <span class="hlt">electron</span> <span class="hlt">transport</span> and precise modeling of GaN high <span class="hlt">electron</span> mobility transistors</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bajaj, Sanyam; Shoron, Omor F.; Park, Pil Sung; Krishnamoorthy, Sriram; Akyol, Fatih; Hung, Ting-Hsiang; Reza, Shahed; Chumbes, Eduardo M.; Khurgin, Jacob; Rajan, Siddharth</p> <p>2015-10-01</p> <p>We report on the direct measurement of two-dimensional sheet charge density dependence of <span class="hlt">electron</span> <span class="hlt">transport</span> in AlGaN/GaN high <span class="hlt">electron</span> mobility transistors (HEMTs). Pulsed IV measurements established increasing <span class="hlt">electron</span> velocities with decreasing sheet charge densities, resulting in saturation velocity of 1.9 × 107 cm/s at a low sheet charge density of 7.8 × 1011 cm-2. An optical phonon emission-based <span class="hlt">electron</span> velocity model for GaN is also presented. It accommodates stimulated longitudinal optical (LO) phonon emission which clamps the <span class="hlt">electron</span> velocity with strong <span class="hlt">electron</span>-phonon interaction and long LO phonon lifetime in GaN. A comparison with the measured density-dependent saturation velocity shows that it captures the dependence rather well. Finally, the experimental result is applied in TCAD-based device simulator to predict DC and small signal characteristics of a reported GaN HEMT. Good agreement between the simulated and reported experimental results validated the measurement presented in this report and established accurate modeling of GaN HEMTs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/22482256','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22482256"><span id="translatedtitle">Density-dependent <span class="hlt">electron</span> <span class="hlt">transport</span> and precise modeling of GaN high <span class="hlt">electron</span> mobility transistors</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Bajaj, Sanyam Shoron, Omor F.; Park, Pil Sung; Krishnamoorthy, Sriram; Akyol, Fatih; Hung, Ting-Hsiang; Reza, Shahed; Chumbes, Eduardo M.; Khurgin, Jacob; Rajan, Siddharth</p> <p>2015-10-12</p> <p>We report on the direct measurement of two-dimensional sheet charge density dependence of <span class="hlt">electron</span> <span class="hlt">transport</span> in AlGaN/GaN high <span class="hlt">electron</span> mobility transistors (HEMTs). Pulsed IV measurements established increasing <span class="hlt">electron</span> velocities with decreasing sheet charge densities, resulting in saturation velocity of 1.9 × 10{sup 7 }cm/s at a low sheet charge density of 7.8 × 10{sup 11 }cm{sup −2}. An optical phonon emission-based <span class="hlt">electron</span> velocity model for GaN is also presented. It accommodates stimulated longitudinal optical (LO) phonon emission which clamps the <span class="hlt">electron</span> velocity with strong <span class="hlt">electron</span>-phonon interaction and long LO phonon lifetime in GaN. A comparison with the measured density-dependent saturation velocity shows that it captures the dependence rather well. Finally, the experimental result is applied in TCAD-based device simulator to predict DC and small signal characteristics of a reported GaN HEMT. Good agreement between the simulated and reported experimental results validated the measurement presented in this report and established accurate modeling of GaN HEMTs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/12535543','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/12535543"><span id="translatedtitle">On the application of quantum <span class="hlt">transport</span> theory to <span class="hlt">electron</span> sources.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Jensen, Kevin L</p> <p>2003-01-01</p> <p><span class="hlt">Electron</span> sources (e.g., field emitter arrays, wide band-gap (WBG) semiconductor materials and coatings, carbon nanotubes, etc.) seek to exploit ballistic <span class="hlt">transport</span> within the vacuum after emission from microfabricated structures. Regardless of kind, all sources strive to minimize the barrier to <span class="hlt">electron</span> emission by engineering material properties (work function/<span class="hlt">electron</span> affinity) or physical geometry (field enhancement) of the cathode. The unique capabilities of cold cathodes, such as instant ON/OFF performance, high brightness, high current density, large transconductance to capacitance ratio, cold emission, small size and/or low voltage operation characteristics, commend their use in several advanced devices when physical size, weight, power consumption, beam current, and pulse repletion frequency are important, e.g., RF power amplifier such as traveling wave tubes (TWTs) for radar and communications, electrodynamic tethers for satellite deboost/reboost, and electric propulsion systems such as Hall thrusters for small satellites. The theoretical program described herein is directed towards models to evaluate emission current from <span class="hlt">electron</span> sources (in particular, emission from WBG and Spindt-type field emitter) in order to assess their utility, capabilities and performance characteristics. Modeling efforts particularly include: band bending, non-linear and resonant (Poole-Frenkel) potentials, the extension of one-dimensional theory to multi-dimensional structures, and emission site statistics due to variations in geometry and the presence of adsorbates. Two particular methodologies, namely, the modified Airy approach and metal-semiconductor statistical hyperbolic/ellipsoidal model, are described in detail in their present stage of development.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22029274','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22029274"><span id="translatedtitle">Toward panchromatic organic functional molecules: density functional theory study on the <span class="hlt">electronic</span> <span class="hlt">absorption</span> spectra of substituted tetraanthracenylporphyrins.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Qi, Dongdong; Jiang, Jianzhuang</p> <p>2011-12-01</p> <p>To achieve full solar spectrum <span class="hlt">absorption</span> of organic dyes for organic solar cells and organic solar antenna collectors, a series of tetraanthracenylporphyrin derivatives including H(2)(TAnP), H(2)(α-F(4)TAnP), H(2)(β,β'-F(8)TAnP), H(2)(γ,γ'-F(8)TAnP), H(2)(δ,δ'-F(8)TAnP), H(2)[α-(NH(2))(4)TAnP], H(2)[β,β'-(NH(2))(8)TAnP], H(2)[γ,γ'-(NH(2))(8)TAnP], and H(2)[δ,δ'-(NH(2))(8)TAnP] was designed and their <span class="hlt">electronic</span> <span class="hlt">absorption</span> spectra were systematically studied on the basis of TDDFT calculations. The nature of the broad and intense <span class="hlt">electronic</span> <span class="hlt">absorptions</span> of H(2)(TAnP) in the range of 500-1700 nm is clearly revealed, and different types of π → π* <span class="hlt">electronic</span> transitions associated with different <span class="hlt">absorption</span> bands are revealed to correspond to different <span class="hlt">electron</span> density moving direction between peripherally fused 14-<span class="hlt">electron</span>-π-conjugated anthracene units and the central 18-<span class="hlt">electron</span>-π-conjugated porphyrin core. Introduction of <span class="hlt">electron</span>-donating groups onto the periphery of the H(2)(TAnP) macrocycle is revealed to be able to lead to novel NIR dyes such as H(2)[α-(NH(2))(4)TAnP] and H(2)[δ,δ'-(NH(2))(8)TAnP] with regulated UV-vis-NIR <span class="hlt">absorption</span> bands covering the full solar spectrum in the range of 300-2400 nm.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016RuPhJ..59..744K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016RuPhJ..59..744K"><span id="translatedtitle"><span class="hlt">Absorption</span> of Light by Free Charge Carriers in the Crystalline CdS Under Intense <span class="hlt">Electron</span> Irradiation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kulikov, V. D.; Yakovlev, V. Yu.</p> <p>2016-09-01</p> <p>The process of light <span class="hlt">absorption</span> by free <span class="hlt">electrons</span> in the crystalline cadmium sulfide under irradiation by a nanosecond <span class="hlt">electron</span> beam with the current density of 8-100 A/cm2 is studied. A superlinear increase in optical <span class="hlt">absorption</span> is observed if the beam current density is increased from ~8 to 12 A/cm2. The nature of light <span class="hlt">absorption</span> by thermalized <span class="hlt">electrons</span> corresponds to the scattering on lattice defects. An increase in the exponent of the power dependence of light <span class="hlt">absorption</span> on the wavelength with increasing beam current density is associated with the single and double ionization of donors and acceptors. It is concluded that accumulation of charge carriers occurs without capture by traps due to their impact ionization by secondary <span class="hlt">electrons</span>, whose energy in the thermalization stage is comparable with the band gap of the crystal. According to the results of calculations, the capture cross section of <span class="hlt">electrons</span> by holes at quadratic recombination is ~10-20 cm2, the Auger recombination coefficient is ~10-31 cm6•s-1, and the charge carrier concentration is ~1.3•1018-1.5•1019 cm-3.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2782827','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2782827"><span id="translatedtitle">Impact of <span class="hlt">Absorption</span> and <span class="hlt">Transport</span> on Intelligent Therapeutics and Nano-scale Delivery of Protein Therapeutic Agents</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Peppas, Nicholas A.; Carr, Daniel A</p> <p>2009-01-01</p> <p>The combination of materials design and advances in nanotechnology has led to the development of new therapeutic protein delivery systems. The pulmonary, nasal, buccal and other routes have been investigated as delivery options for protein therapy, but none result in improved patient compliances and patient quality of life as the oral route. For the oral administration of these new systems, an understanding of protein <span class="hlt">transport</span> is essential because of the dynamic nature of the gastrointestinal tract and the barriers to <span class="hlt">transport</span> that exist. Models have been developed to describe the <span class="hlt">transport</span> between the gastrointestinal lumen and the bloodstream, and laboratory techniques like cell culture provide a means to investigate the <span class="hlt">absorption</span> and <span class="hlt">transport</span> of many therapeutic agents. Biomaterials, including stimuli-sensitive complexation hydrogels, have been investigated as promising carriers for oral delivery. However, the need to develop models that accurately predict protein blood concentration as a function of the material structure and properties still exists. PMID:20161384</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005JChPh.122m4506B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005JChPh.122m4506B"><span id="translatedtitle">The role of solvent structure in the <span class="hlt">absorption</span> spectrum of solvated <span class="hlt">electrons</span>: Mixed quantum/classical simulations in tetrahydrofuran</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bedard-Hearn, Michael J.; Larsen, Ross E.; Schwartz, Benjamin J.</p> <p>2005-04-01</p> <p>In polar fluids such as water and methanol, the peak of the solvated <span class="hlt">electron</span>'s <span class="hlt">absorption</span> spectrum in the red has been assigned as a sum of transitions between an s-like ground state and three nearly degenerate p-like excited states bound in a quasispherical cavity. In contrast, in weakly polar solvents such as tetrahydrofuran (THF), the solvated <span class="hlt">electron</span> has an <span class="hlt">absorption</span> spectrum that peaks in the mid-infrared, but no definitive assignment has been offered about the origins of the spectrum or the underlying structure. In this paper, we present the results of adiabatic mixed quantum/classical molecular dynamic simulations of the solvated <span class="hlt">electron</span> in THF, and provide a detailed explanation of the THF-solvated <span class="hlt">electron</span>'s <span class="hlt">absorption</span> spectrum and <span class="hlt">electronic</span> structure. Using a classical solvent model and a fully quantum mechanical excess <span class="hlt">electron</span>, our simulations show that although the ground and first excited states are bound in a quasispherical cavity, a multitude of other, nearby solvent cavities support numerous, nearly degenerate, bound excited states that have little Franck-Condon overlap with the ground state. We show that these solvent cavities, which are partially polarized so that they act as <span class="hlt">electron</span> trapping sites, are an inherent property of the way THF molecules pack in the liquid. The <span class="hlt">absorption</span> spectrum is thus assigned to a sum of bound-to-bound transitions between a localized ground state and multiple disjoint excited states scattered throughout the fluid. Furthermore, we find that the usual spherical harmonic labels (e.g., s-like, p-like) are not good descriptors of the excited-state wave functions of the solvated <span class="hlt">electron</span> in THF. Our observation of multiple disjoint excited states is consistent with femtosecond pump-probe experiments in the literature that suggest that photoexcitation of solvated <span class="hlt">electrons</span> in THF causes them to relocalize into solvent cavities far from where they originated.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25900515','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25900515"><span id="translatedtitle">Involvement of Concentrative Nucleoside <span class="hlt">Transporter</span> 1 in Intestinal <span class="hlt">Absorption</span> of Trifluridine Using Human Small Intestinal Epithelial Cells.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Takahashi, Koichi; Yoshisue, Kunihiro; Chiba, Masato; Nakanishi, Takeo; Tamai, Ikumi</p> <p>2015-09-01</p> <p>TAS-102, which is effective for refractory metastatic colorectal cancer, is a combination drug of anticancer trifluridine (FTD; which is derived from pyrimidine nucleoside) and FTD-metabolizing enzyme inhibitor tipiracil hydrochloride (TPI) at a molecular ratio of 1:0.5. To evaluate the intestinal <span class="hlt">absorption</span> mechanism of FTD, the uptake and transcellular <span class="hlt">transport</span> of FTD by human small intestinal epithelial cell (HIEC) monolayer as a model of human intestinal epithelial cells was investigated. The uptake and membrane permeability of FTD by HIEC monolayers were saturable, Na(+) -dependent, and inhibited by nucleosides. These <span class="hlt">transport</span> characteristics are mostly comparable with those of concentrative nucleoside <span class="hlt">transporters</span> (CNTs). Moreover, the uptake of FTD by CNT1-expressing Xenopus oocytes was the highest among human CNT <span class="hlt">transporters</span>. The obtained Km and Vmax values of FTD by CNT1 were 69.0 μM and 516 pmol/oocyte/30 min, respectively. The transcellular <span class="hlt">transport</span> of FTD by Caco-2 cells, where CNT1 is heterologously expressed, from apical to basolateral side was greater than that by Mock cells. In conclusion, these results demonstrated that FTD exhibits high oral <span class="hlt">absorption</span> by the contribution of human CNT1.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_19 --> <div id="page_20" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="381"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AIPC.1728b0669B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AIPC.1728b0669B"><span id="translatedtitle">Effect of doping on the <span class="hlt">electron</span> <span class="hlt">transport</span> in polyfluorene</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bajpai, Manisha; Srivastava, Ritu; Dhar, Ravindra; Tiwari, R. S.</p> <p>2016-05-01</p> <p>In this paper, <span class="hlt">electron</span> <span class="hlt">transport</span> of pure and DMC doped polyfluorne (PF) films have been studied at various doping concentrations. Pure films show space charge limited conduction with field and temperature dependent mobility. The J-V characteristics of doped PF were ohmic at low voltages due to thermally released carriers from dopant states. At higher voltages the current density increases nonlinearly due to field dependent mobility and carrier concentration thereby filling of tail states of HOMO of the host. The conductivity of doped fims were analyzed using the Unified Gaussian Disorder Model (UGDM). The carrier concentration obtained from the fitting show a non-linear dependence on doping concentration which may be due to a combined effect of thermally activated carrier generation and increased carrier mobility.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016APS..MARC26001B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016APS..MARC26001B"><span id="translatedtitle"><span class="hlt">Electron</span> <span class="hlt">Transport</span> Simulations of 4-Terminal Crossed Graphene Nanoribbons Devices</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Brandimarte, Pedro; Papior, Nick R.; Engelund, Mads; Garcia-Lekue, Aran; Frederiksen, Thomas; Sánchez-Portal, Daniel</p> <p></p> <p>Recently, it has been reported theoretically a current switching mechanism by voltage control in a system made by two perpendicular 14-armchair graphene nanoribbons (GNRs). In order to investigate the possibilities of using crossed GNRs as ON/OFF devices, we have studied their <span class="hlt">electronic</span> and <span class="hlt">transport</span> properties as function structural parameters determining the crossing. Our calculations were performed with TranSIESTA code, which has been recently generalized to consider N >= 1 arbitrarily distributed electrodes at finite bias. We find that the transmission along each individual GNR and among them strongly depends on the stacking. For a 60° rotation angle, the lattice matching in the crossing region provokes a strong scattering effect that translates into an increased interlayer transmission. FP7 FET-ICT PAMS-project (European Commission, contract 610446), MINECO (Grant MAT2013-46593-C6-2-P) and Basque Dep. de Educación, UPV/EHU (Grant IT-756-13).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/22492133','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22492133"><span id="translatedtitle">Conformation dependent <span class="hlt">electronic</span> <span class="hlt">transport</span> in a DNA double-helix</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Kundu, Sourav Karmakar, S. N.</p> <p>2015-10-15</p> <p>We present a tight-binding study of conformation dependent <span class="hlt">electronic</span> <span class="hlt">transport</span> properties of DNA double-helix including its helical symmetry. We have studied the changes in the localization properties of DNA as we alter the number of stacked bases within every pitch of the double-helix keeping fixed the total number of nitrogen bases within the DNA molecule. We take three DNA sequences, two of them are periodic and one is random and observe that in all the cases localization length increases as we increase the radius of DNA double-helix i.e., number of nucleobases within a pitch. We have also investigated the effect of backbone energetic on the I-V response of the system and found that in presence of helical symmetry, depending on the interplay of conformal variation and disorder, DNA can be found in either metallic, semiconducting and insulating phases, as observed experimentally.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005ApPhL..87w3509G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005ApPhL..87w3509G"><span id="translatedtitle">Device structure for <span class="hlt">electronic</span> <span class="hlt">transport</span> through individual molecules using nanoelectrodes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ghosh, Subhasis; Halimun, Henny; Mahapatro, Ajit Kumar; Choi, Jaewon; Lodha, Saurabh; Janes, David</p> <p>2005-12-01</p> <p>We present a simple and reliable method for making electrical contacts to small organic molecules with thiol endgroups. Nanometer-scale gaps between metallic electrodes have been fabricated by passing a large current through a lithographically-patterned Au-line with appropriate thickness. Under appropriate conditions, the passage of current breaks the Au-line, creating two opposite facing electrodes separated by a gap comparable to the length of small organic molecules. Current-voltage characteristics have been measured both before and after deposition of short organic molecules. The resistance of single 1,4-benzenedithiol and 1,4-bezenedimethanedithiol molecules were found to be 9MΩ and 26MΩ, respectively. The experimental results indicate strong <span class="hlt">electronic</span> coupling to the contacts and are discussed using a relatively simple model of mesoscopic <span class="hlt">transport</span>. The use of electrodes formed on an insulating surface by lithography and electromigration provides a stable structure suitable for integrated circuit applications.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1009202','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1009202"><span id="translatedtitle">Hot <span class="hlt">Electron</span> Generation and <span class="hlt">Transport</span> Using K(alpha) Emission</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Akli, K U; Stephens, R B; Key, M H; Bartal, T; Beg, F N; Chawla, S; Chen, C D; Fedosejevs, R; Freeman, R R; Friesen, H; Giraldez, E; Green, J S; Hey, D S; Higginson, D P; Hund, J; Jarrott, L C; Kemp, G E; King, J A; Kryger, A; Lancaster, K; LePape, S; Link, A; Ma, T; Mackinnon, A J; MacPhee, A G; McLean, H S; Murphy, C; Norreys, P A; Ovchinnikov, V; Patel, P K; Ping, Y; Sawada, H; Schumacher, D; Theobald, W; Tsui, Y Y; Van Woerkom, L D; Wei, M S; Westover, B; Yabuuchi, T</p> <p>2009-10-15</p> <p>We have conducted experiments on both the Vulcan and Titan laser facilities to study hot <span class="hlt">electron</span> generation and <span class="hlt">transport</span> in the context of fast ignition. Cu wires attached to Al cones were used to investigate the effect on coupling efficiency of plasma surround and the pre-formed plasma inside the cone. We found that with thin cones 15% of laser energy is coupled to the 40{micro}m diameter wire emulating a 40{micro}m fast ignition spot. Thick cone walls, simulating plasma in fast ignition, reduce coupling by x4. An increase of prepulse level inside the cone by a factor of 50 reduces coupling by a factor of 3.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EPJB...89..191Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EPJB...89..191Z"><span id="translatedtitle"><span class="hlt">Electronic</span> <span class="hlt">transport</span> properties of a quinone-based molecular switch</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zheng, Ya-Peng; Bian, Bao-An; Yuan, Pei-Pei</p> <p>2016-09-01</p> <p>In this paper, we carried out first-principles calculations based on density functional theory and non-equilibrium Green's function to investigate the <span class="hlt">electronic</span> <span class="hlt">transport</span> properties of a quinone-based molecule sandwiched between two Au electrodes. The molecular switch can be reversibly switched between the reduced hydroquinone (HQ) and oxidized quinone (Q) states via redox reactions. The switching behavior of two forms is analyzed through their I- V curves, transmission spectra and molecular projected self-consistent Hamiltonian at zero bias. Then we discuss the transmission spectra of the HQ and Q forms at different bias, and explain the oscillation of current according to the transmission eigenstates of LUMO energy level for Q form. The results suggest that this kind of a quinone-based molecule is usable as one of the good candidates for redox-controlled molecular switches.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2011PhyE...43.1655S&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2011PhyE...43.1655S&link_type=ABSTRACT"><span id="translatedtitle"><span class="hlt">Electronic</span> <span class="hlt">transport</span> characteristics in silicon nanotube field-effect transistors</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Shan, Guangcun; Wang, Yu; Huang, Wei</p> <p>2011-07-01</p> <p>The successful synthesis of silicon nanotubes (SiNTs) has been reported, making these nanostructures a new novel candidate for future nanodevices. By self-consistently solving the Poisson equations using the non-equilibrium Green's function (NEGF) formalism, we investigate the <span class="hlt">electronic</span> <span class="hlt">transport</span> and the role of gate bias in affecting the drive current of single-walled silicon nanotube (SW-SiNT) field-effect transistors (FETs). By comparison of a SW-CNT FET, it is found that the SW-SiNT with a high- k HfO gate oxide is a promising candidate for nanotube transistor with better performance. The results discussed here would serve as a versatile and powerful guideline for future experimental studies of SW-SiNT-based transistor with the purpose of exploring device application for nanoelectronics.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016APS..MAR.F5008Q','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016APS..MAR.F5008Q"><span id="translatedtitle"><span class="hlt">Electronic</span> measurement of strain effects on spin <span class="hlt">transport</span> in silicon</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Qing, Lan; Tinkey, Holly; Appelbaum, Ian</p> <p></p> <p>Spin <span class="hlt">transport</span> in silicon is limited by the Elliott-Yafet spin relaxation mechanism, which is driven by scattering between degenerate conduction band valleys. Mechanical strain along a valley axis partially breaks this degeneracy, and will ultimately quench intervalley spin relaxation for transitions between states on orthogonal axes. Using a custom-designed and constructed strain probe, we study the effects of uniaxial compressive strain along the < 100 > direction on ballistic tunnel junction devices used to inject spin-polarized <span class="hlt">electrons</span> into silicon. The effects of strain-induced valley splitting will be presented and compared to our theoretical model. This work is supported by the Office of Naval Research under Contract No. N000141410317, the National Science Foundation under Contract No. ECCS-1231855, the Defense Threat Reduction Agency under Contract No. HDTRA1-13-1-0013, and the Maryland NanoCenter.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/984468','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/984468"><span id="translatedtitle">Anomalous <span class="hlt">Electron</span> <span class="hlt">Transport</span> Due to Multiple High Frequency Beam Ion Driven Alfven Eigenmode</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Gorelenkov, N. N.; Stutman, D.; Tritz, K.; Boozer, A.; Delgardo-Aparicio, L.; Fredrickson, E.; Kaye, S.; White, R.</p> <p>2010-07-13</p> <p>We report on the simulations of recently observed correlations of the core <span class="hlt">electron</span> <span class="hlt">transport</span> with the sub-thermal ion cyclotron frequency instabilities in low aspect ratio plasmas of the National Spherical Torus Experiment (NSTX). In order to model the <span class="hlt">electron</span> <span class="hlt">transport</span> of the guiding center code ORBIT is employed. A spectrum of test functions of multiple core localized Global shear Alfven Eigenmode (GAE) instabilities based on a previously developed theory and experimental observations is used to examine the <span class="hlt">electron</span> <span class="hlt">transport</span> properties. The simulations exhibit thermal <span class="hlt">electron</span> <span class="hlt">transport</span> induced by <span class="hlt">electron</span> drift orbit stochasticity in the presence of multiple core localized GAE.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006CPL...425..257K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006CPL...425..257K"><span id="translatedtitle"><span class="hlt">Electronically</span> excited dipole moment of 4-aminobenzonitrile from thermochromic <span class="hlt">absorption</span> and fluorescence measurements</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kawski, A.; Kukliński, B.; Bojarski, P.</p> <p>2006-07-01</p> <p>The effect of temperature on <span class="hlt">absorption</span> and fluorescence spectra of 4-aminobenzonitrile (ABN) in 1,2-dichloroethane is studied for temperature ranging from 296 K to 343 K. The analysis of <span class="hlt">absorption</span> and fluorescence band shift on the basis of Bilot and Kawski theory [L. Bilot, A. Kawski, Z. Naturforsch. 17a (1962) 621], for the known dipole moment in the ground state μg = 5.92 D, and α/ a3 = 0.5 ( α is the polarizability and a is the Onsager interaction radius of the solute) yields for ABN: (1) the empirical Onsager interaction radius a = 3.3 Å, (2) the dipole moment in the excited S 1 state μe = 7.14 D which agrees very well with the value of μe = 7.20 D obtained by Borst et al. [D.R. Borst, T.M. Korter, D.W. Pratt, Chem. Phys. Lett. 350 (2001) 485] from Stark effect studies. Both values of μe concern free ABN molecule and differ significantly from the values of μg (8.0 D, 8.5 D and 8.3 D in cyclohexane, benzene and 1,4-dioxane, respectively) obtained by Schuddeboom et al. [W. Schuddeboom, S.A. Jonker, J.M. Warman, U. Leinhos, W. Kühnle, K.A. Zachariasse, J. Phys. Chem. 96 (1992) 10809] from the time-resolved microwave conductivity measurements which are solvent-dependent. The group moment additivity law in the case of ABN molecule is approximately applicable, both in the ground and in the excited <span class="hlt">electronic</span> state.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009PhDT.......167B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009PhDT.......167B"><span id="translatedtitle">Characterization of ionic <span class="hlt">transport</span> in polymer and <span class="hlt">electronic</span> <span class="hlt">transport</span> in disordered selenium and ceramic materials</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bandyopadhyay, Subhasish</p> <p></p> <p>In this thesis, the properties of <span class="hlt">electronic</span> conduction in vanadium (donor) and scandium (acceptor) doped Ba0.7Sr0.3TiO3 ceramics, amorphous Selenium and ionic conduction in polyester polyol based polyurethane have been investigated. The leakage current of bulk vanadium (donor) and scandium (acceptor) doped Ba0.7Sr0.3TiO3 ceramics structures measured using gold electrical contacts have been characterized and analyzed. Vanadium doping reduces the ohmic leakage current that dominates the <span class="hlt">transport</span> characteristics up to 5 kV/cm. The Arrhenius activation energy is 0.18, 0.20 and 0.23 eV for 1, 2 and 4 at % V-doped samples, respectively. Above this field, the current-voltage characteristics exhibit discontinuous current transitions associated with trap filling by <span class="hlt">electronic</span> carriers. At higher fields, trap controlled space charge limited conduction (SCLC) is observed with an effective mobility of 4+/-1x10-7 cm2/V s, characteristic of <span class="hlt">electronic</span> <span class="hlt">transport</span> process that involves quasi equilibrium between conduction in the band and trapping. In contrast, the leakage current of Sc-doped samples increases with impurity concentration and exhibits a 0.60 eV activation energy. In this case, the limiting current conduction mechanism is the <span class="hlt">transport</span> of holes over the electrostatic barrier at grain boundaries. Comparison of these results to those on similarly-doped homoepitaxial SrTiO3 thin-films deposited on single-crystal and bicrystal substrates helped to identify the characteristics of <span class="hlt">transport</span> in the bulk and across grain boundaries for this class of materials. Electrical, thermal and Li <span class="hlt">transport</span> properties have been measured for polyester polyol and isocyanate-based polyurethanes doped with Lithium trifluoromethanesulfonimide (LiTFSI) and Lithium perchlorate (LiClO4) Electrical conductivities are estimated at 10-5--10-6 S/cm near 300 K. The conductivities show Vogel-Tammann-Fulcher (VTF) behavior over a wide temperature ranges. Differential scanning calorimetry (DSC) shows</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016PPCF...58e5002K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016PPCF...58e5002K"><span id="translatedtitle">Simple predictive <span class="hlt">electron</span> <span class="hlt">transport</span> models applied to sawtoothing plasmas</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kim, D.; Merle, A.; Sauter, O.; Goodman, T. P.</p> <p>2016-05-01</p> <p>In this work, we introduce two simple <span class="hlt">transport</span> models to evaluate the time evolution of <span class="hlt">electron</span> temperature and density profiles during sawtooth cycles (i.e. over a sawtooth period time-scale). Since the aim of these simulations is to estimate reliable profiles within a short calculation time, two simplified ad-hoc models have been developed. The goal for these models is to rely on a few easy-to-check free parameters, such as the confinement time scaling factor and the profiles’ averaged scale-lengths. Due to the simplicity and short calculation time of the models, it is expected that these models can also be applied to real-time <span class="hlt">transport</span> simulations. We show that it works well for Ohmic and EC heated L- and H-mode plasmas. The differences between these models are discussed and we show that their predictive capabilities are similar. Thus only one model is used to reproduce with simulations the results of sawtooth control experiments on the TCV tokamak. For the sawtooth pacing, the calculated time delays between the EC power off and sawtooth crash time agree well with the experimental results. The map of possible locking range is also well reproduced by the simulation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/22493896','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22493896"><span id="translatedtitle"><span class="hlt">Electron</span> <span class="hlt">transport</span> in molecular junctions with graphene as protecting layer</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Hüser, Falco; Solomon, Gemma C.</p> <p>2015-12-07</p> <p>We present ab initio <span class="hlt">transport</span> calculations for molecular junctions that include graphene as a protecting layer between a single molecule and gold electrodes. This vertical setup has recently gained significant interest in experiment for the design of particularly stable and reproducible devices. We observe that the signals from the molecule in the <span class="hlt">electronic</span> transmission are overlayed by the signatures of the graphene sheet, thus raising the need for a reinterpretation of the transmission. On the other hand, we see that our results are stable with respect to various defects in the graphene. For weakly physiosorbed molecules, no signs of interaction with the graphene are evident, so the <span class="hlt">transport</span> properties are determined by offresonant tunnelling between the gold leads across an extended structure that includes the molecule itself and the additional graphene layer. Compared with pure gold electrodes, calculated conductances are about one order of magnitude lower due to the increased tunnelling distance. Relative differences upon changing the end group and the length of the molecule on the other hand, are similar.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015JChPh.143u4302H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JChPh.143u4302H"><span id="translatedtitle"><span class="hlt">Electron</span> <span class="hlt">transport</span> in molecular junctions with graphene as protecting layer</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hüser, Falco; Solomon, Gemma C.</p> <p>2015-12-01</p> <p>We present ab initio <span class="hlt">transport</span> calculations for molecular junctions that include graphene as a protecting layer between a single molecule and gold electrodes. This vertical setup has recently gained significant interest in experiment for the design of particularly stable and reproducible devices. We observe that the signals from the molecule in the <span class="hlt">electronic</span> transmission are overlayed by the signatures of the graphene sheet, thus raising the need for a reinterpretation of the transmission. On the other hand, we see that our results are stable with respect to various defects in the graphene. For weakly physiosorbed molecules, no signs of interaction with the graphene are evident, so the <span class="hlt">transport</span> properties are determined by offresonant tunnelling between the gold leads across an extended structure that includes the molecule itself and the additional graphene layer. Compared with pure gold electrodes, calculated conductances are about one order of magnitude lower due to the increased tunnelling distance. Relative differences upon changing the end group and the length of the molecule on the other hand, are similar.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25936131','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25936131"><span id="translatedtitle">Fluorine effects in new indenofluorenedione derivatives for <span class="hlt">electron</span> <span class="hlt">transporting</span> layer in OLED devices.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Lee, Jaehyun; Kim, Beomjin; Park, Youngil; Kim, Seungho; Park, Jongwook</p> <p>2014-08-01</p> <p>New three indenofluorenedione derivatives were synthesized and proposed for <span class="hlt">electron</span> <span class="hlt">transporting</span> layer (ETL). Three compounds are indeno[1,2-b]fluorene-6,12-dione (IF-dione), 2,8-Difluoro-indeno[1,2-b]fluorene-6,12-dione (Mono-F-lF-dione), and 1,2,3,7,8,9-Hexafluoro-indeno[1,2- b]fluorene-6,12-dione (Tri-F-IF-dione). UV-visible (UV-Vis) <span class="hlt">absorption</span> of three compounds in THF solution state showed different <span class="hlt">absorption</span> maximum values as follows: 292, 318 and 334 nm (IF-dione), 289, 314 and 329 nm (Mono-F-IF-dione), 285, 319 and 334 nm (Tri-F-IF-dione). Three compounds were inserted between emitting layer (EML) and cathode electrode as an ETL in OLED device: ITO/2-TNATA (60 nm)/NPB (15 nm)/Alq3 (30 nm)/synthesized compounds (30 nm)/LiF (1 nm)/Al (200 nm). I-V characteristics of three devices were investigated at 20 mA/cm2. Operating voltages of three compounds were 7.06 V (IF-dione), 6.42 V (MonoF-IF-dione), 5.36 V (TriF-IF-dione), respectively.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016SPIE.9840E..1EH','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016SPIE.9840E..1EH"><span id="translatedtitle">Calculation of vibrational and <span class="hlt">electronic</span> excited state <span class="hlt">absorption</span> spectra of arsenic-water complexes using density functional theory</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Huang, L.; Lambrakos, S. G.; Shabaev, A.; Massa, L.</p> <p>2016-05-01</p> <p>Calculations are presented of vibrational and <span class="hlt">electronic</span> excited-state <span class="hlt">absorption</span> spectra for As-H2O complexes using density function theory (DFT) and time-dependent density functional theory (TD-DFT). DFT and TD-DFT can provide interpretation of <span class="hlt">absorption</span> spectra with respect to molecular structure for excitation by electromagnetic waves at frequencies within the IR and UV-visible ranges. The <span class="hlt">absorption</span> spectrum corresponding to excitation states of As-H2O complexes consisting of relatively small numbers of water molecules should be associated with response features that are intermediate between that of isolated molecules and that of a bulk system. DFT and TD-DFT calculated <span class="hlt">absorption</span> spectra represent quantitative estimates that can be correlated with additional information obtained from laboratory measurements and other types of theory based calculations. The DFT software GAUSSIAN was used for the calculations of excitation states presented here.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007ChPhL..24.1042O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007ChPhL..24.1042O"><span id="translatedtitle"><span class="hlt">Electronic</span> <span class="hlt">Transport</span> in Molecular Junction Based on C20 Cages</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ouyang, Fang-Ping; Xu, Hui</p> <p>2007-04-01</p> <p>Choosing closed-ended armchair (5, 5) single-wall carbon nanotubes (CCNTs) as electrodes, we investigate the <span class="hlt">electron</span> <span class="hlt">transport</span> properties across an all-carbon molecular junction consisting of C20 molecules suspended between two semi-infinite carbon nanotubes. It is shown that the conductances are quite sensitive to the number of C20 molecules between electrodes for both configuration CF1 and double-bonded models: the conductances of C20 dimers are markedly smaller than those of monomers. The physics is that incident <span class="hlt">electrons</span> easily pass the C20 molecules and are predominantly scattered at the C20-C20 junctions. Moreover, we study the doping effect of such molecular junction by doping nitrogen atoms substitutionally. The bonding property of the molecular junction with configuration CF1 has been analysed by calculating the Mulliken atomic charges. Our results have revealed that the C atoms in N-doped junctions are more ionic than those in pure-carbon ones, leading to the fact that N-doped junctions have relatively large conductance.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/15328348','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/15328348"><span id="translatedtitle">Oxygen tolerance and coupling of mitochondrial <span class="hlt">electron</span> <span class="hlt">transport</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Campian, Jian Li; Qian, Mingwei; Gao, Xueshan; Eaton, John W</p> <p>2004-11-01</p> <p>Oxygen is critical to aerobic metabolism, but excessive oxygen (hyperoxia) causes cell injury and death. An oxygen-tolerant strain of HeLa cells, which proliferates even under 80% O2, termed "HeLa-80," was derived from wild-type HeLa cells ("HeLa-20") by selection for resistance to stepwise increases of oxygen partial pressure. Surprisingly, antioxidant defenses and susceptibility to oxidant-mediated killing do not differ between these two strains of HeLa cells. However, under both 20 and 80% O2, intracellular reactive oxygen species (ROS) production is significantly (approximately 2-fold) less in HeLa-80 cells. In both cell lines the source of ROS is evidently mitochondrial. Although HeLa-80 cells consume oxygen at the same rate as HeLa-20 cells, they consume less glucose and produce less lactic acid. Most importantly, the oxygen-tolerant HeLa-80 cells have significantly higher cytochrome c oxidase activity (approximately 2-fold), which may act to deplete upstream <span class="hlt">electron</span>-rich intermediates responsible for ROS generation. Indeed, preferential inhibition of cytochrome c oxidase by treatment with n-methyl protoporphyrin (which selectively diminishes synthesis of heme a in cytochrome c oxidase) enhances ROS production and abrogates the oxygen tolerance of the HeLa-80 cells. Thus, it appears that the remarkable oxygen tolerance of these cells derives from tighter coupling of the <span class="hlt">electron</span> <span class="hlt">transport</span> chain. PMID:15328348</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/969243','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/969243"><span id="translatedtitle">Near Edge X-Ray <span class="hlt">Absorption</span> Fine Structure Spectroscopy with X-Ray Free-<span class="hlt">Electron</span> Lasers</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Bernstein, D.P.; Acremann, Y.; Scherz, A.; Burkhardt, M.; Stohr, J.; Beye, M.; Schlotter, W.F.; Beeck, T.; Sorgenfrei, F.; Pietzsch, A.; Wurth, W.; Fohlisch, A.; /Hamburg U.</p> <p>2009-12-11</p> <p>We demonstrate the feasibility of Near Edge X-ray <span class="hlt">Absorption</span> Fine Structure (NEXAFS) spectroscopy on solids by means of femtosecond soft x-ray pulses from a free-<span class="hlt">electron</span> laser (FEL). Our experiments, carried out at the Free-<span class="hlt">Electron</span> Laser at Hamburg (FLASH), used a special sample geometry, spectrographic energy dispersion, single shot position-sensitive detection and a data normalization procedure that eliminates the severe fluctuations of the incident intensity in space and photon energy. As an example we recorded the {sup 3}D{sub 1} N{sub 4,5}-edge <span class="hlt">absorption</span> resonance of La{sup 3+}-ions in LaMnO{sub 3}. Our study opens the door for x-ray <span class="hlt">absorption</span> measurements on future x-ray FEL facilities.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/404063','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/404063"><span id="translatedtitle">Nonlinear intersubband <span class="hlt">absorption</span> of a hot quasi-two-dimensional <span class="hlt">electron</span> plasma studied by femtosecond infrared spectroscopy</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Lutgen, S.; Kaindl, R.A.; Woerner, M.; Elsaesser, T.; Hase, A.; Kuenzel, H.</p> <p>1996-12-01</p> <p>The transient ({ital n}=1) to ({ital n}=2) intersubband <span class="hlt">absorption</span> of a pure <span class="hlt">electron</span> plasma in {ital n}-type Ga{sub 0.48}In{sub 0.53}As/Al{sub 0.48}In{sub 0.52}As quantum wells is studied in femtosecond pump-probe experiments. The ultrafast dynamics of nonlinear <span class="hlt">absorption</span> shows strong changes when tuning the midinfrared pulses over the intersubband <span class="hlt">absorption</span> line. The nonlinear optical response is determined by both intersubband relaxation with a time constant of 1.3 ps and the intraband dynamics of ({ital n}=1) <span class="hlt">electrons</span>, which are monitored in an independent experiment. {copyright} {ital 1996 The American Physical Society.}</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_20 --> <div id="page_21" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active"><span>21</span></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="401"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23115084','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23115084"><span id="translatedtitle">Clinical significance of organic anion <span class="hlt">transporting</span> polypeptides (OATPs) in drug disposition: their roles in hepatic clearance and intestinal <span class="hlt">absorption</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Shitara, Yoshihisa; Maeda, Kazuya; Ikejiri, Kazuaki; Yoshida, Kenta; Horie, Toshiharu; Sugiyama, Yuichi</p> <p>2013-01-01</p> <p>Organic anion <span class="hlt">transporting</span> polypeptide (OATP) family <span class="hlt">transporters</span> accept a number of drugs and are increasingly being recognized as important factors in governing drug and metabolite pharmacokinetics. OATP1B1 and OATP1B3 play an important role in hepatic drug uptake while OATP2B1 and OATP1A2 might be key players in intestinal <span class="hlt">absorption</span> and <span class="hlt">transport</span> across blood-brain barrier of drugs, respectively. To understand the importance of OATPs in the hepatic clearance of drugs, the rate-determining process for elimination should be considered; for some drugs, hepatic uptake clearance rather than metabolic intrinsic clearance is the more important determinant of hepatic clearances. The importance of the unbound concentration ratio (liver/blood), K(p,uu) , of drugs, which is partly governed by OATPs, is exemplified in interpreting the difference in the IC(50) of statins between the hepatocyte and microsome systems for the inhibition of HMG-CoA reductase activity. The intrinsic activity and/or expression level of OATPs are affected by genetic polymorphisms and drug-drug interactions. Their effects on the elimination rate or intestinal <span class="hlt">absorption</span> rate of drugs may sometimes depend on the substrate drug. This is partly because of the different contribution of OATP isoforms to clearance or intestinal <span class="hlt">absorption</span>. When the contribution of the OATP-mediated pathway is substantial, the pharmacokinetics of substrate drugs should be greatly affected. This review describes the estimation of the contribution of OATP1B1 to the total hepatic uptake of drugs from the data of fold-increases in the plasma concentration of substrate drugs by the genetic polymorphism of this <span class="hlt">transporter</span>. To understand the importance of the OATP family <span class="hlt">transporters</span>, modeling and simulation with a physiologically based pharmacokinetic model are helpful.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/100296','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/100296"><span id="translatedtitle">Multigroup Boltzmann Fokker Planck <span class="hlt">electron</span>-photon <span class="hlt">transport</span> capability in MCNP{sup trademark}</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Adams, K.J.; Hart, M.</p> <p>1995-07-01</p> <p>The MCNP code system has a robust multigroup <span class="hlt">transport</span> capability which includes a multigroup Boltzmann-Fokker-Planck (MGBFP) <span class="hlt">transport</span> algorithm to perform coupled <span class="hlt">electron</span>-photon or other coupled charged and neutral particle <span class="hlt">transport</span> in either a forward or adjoint mode. This paper will discuss this capability and compare code results with other <span class="hlt">transport</span> codes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5590089','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5590089"><span id="translatedtitle">Flash spectroscopic characterization of photosynthetic <span class="hlt">electron</span> <span class="hlt">transport</span> in isolated heterocysts</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Houchins, J.P.; Hind, G.</p> <p>1983-07-01</p> <p><span class="hlt">Electron</span> <span class="hlt">transport</span> was studied in heterocysts of the filamentous cyanobacterium Anabaena 7120 using spectral and kinetic analysis of absorbance transients elicited by single turnover flashes. Consistent photosynthetic turnovers were observed only in the presence of an exogenous source of reductant; therefore measurements were routinely made under a gas phase containing H2. Prominent absorbance changes corresponding to the oxidation of cytochrome c (554 nm) and the reduction of cytochrome b563 (563 nm) were observed. Under the most reducing conditions (99% H2/1% O2) cytochrome b563 was partially reduced between flashes in a slow, dark reaction. At 10-15% O2, the slow, dark reduction of cytochrome b563 was eliminated. Cytochrome turnover ceased entirely at high O2 concentrations (30%) but was restored by the addition of 25 microM KCN, demonstrating an interaction between the photosynthetic and respiratory <span class="hlt">electron</span> transfer chains. Strobilurin A slowed the re-reduction of cytochrome c and eliminated the appearance of reduced cytochrome b563 by blocking <span class="hlt">electron</span> transfer between reduced plastoquinone and the cytochrome b/f complex. Inhibition at a second site was apparent with 2-(n-heptyl)-4-hydroxyquinoline N-oxide, which blocked the reoxidation of cytochrome b563 but had little effect on cytochrome c relaxation. In uncoupled heterocysts, the rates of cytochrome c re-reduction and cytochrome b563 reduction were equal. Additional unassigned absorbance changes at 475 nm, 515 nm, and 572 nm were partially characterized. No absorbance change corresponding to an electrochromic shift was observed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/27314253','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/27314253"><span id="translatedtitle">Revealing <span class="hlt">electronic</span> structure changes in Chevrel phase cathodes upon Mg insertion using X-ray <span class="hlt">absorption</span> spectroscopy.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wan, Liwen F; Wright, Joshua; Perdue, Brian R; Fister, Timothy T; Kim, Soojeong; Apblett, Christopher A; Prendergast, David</p> <p>2016-06-29</p> <p>Following previous work predicting the <span class="hlt">electronic</span> response of the Chevrel phase Mo6S8 upon Mg insertion (Thöle et al., Phys. Chem. Chem. Phys., 2015, 17, 22548), we provide the experimental proof, evident in X-ray <span class="hlt">absorption</span> spectroscopy, to illustrate the charge compensation mechanism of the Chevrel phase compound during Mg insertion and de-insertion processes. PMID:27314253</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016PlPhR..42..713G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016PlPhR..42..713G"><span id="translatedtitle">Simulation of <span class="hlt">electron</span> beam formation and <span class="hlt">transport</span> in a gas-filled <span class="hlt">electron</span>-optical system with a plasma emitter</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Grishkov, A. A.; Kornilov, S. Yu.; Rempe, N. G.; Shidlovskiy, S. V.; Shklyaev, V. A.</p> <p>2016-07-01</p> <p>The results of computer simulations of the <span class="hlt">electron</span>-optical system of an <span class="hlt">electron</span> gun with a plasma emitter are presented. The simulations are performed using the KOBRA3-INP, XOOPIC, and ANSYS codes. The results describe the <span class="hlt">electron</span> beam formation and <span class="hlt">transport</span>. The <span class="hlt">electron</span> trajectories are analyzed. The mechanisms of gas influence on the energy inhomogeneity of the beam and its current in the regions of beam primary formation, acceleration, and <span class="hlt">transport</span> are described. Recommendations for optimizing the <span class="hlt">electron</span>-optical system with a plasma emitter are presented.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25255961','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25255961"><span id="translatedtitle">Basic concepts of quantum interference and <span class="hlt">electron</span> <span class="hlt">transport</span> in single-molecule <span class="hlt">electronics</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Lambert, C J</p> <p>2015-02-21</p> <p>This tutorial outlines the basic theoretical concepts and tools which underpin the fundamentals of phase-coherent <span class="hlt">electron</span> <span class="hlt">transport</span> through single molecules. The key quantity of interest is the transmission coefficient T(E), which yields the electrical conductance, current-voltage relations, the thermopower S and the thermoelectric figure of merit ZT of single-molecule devices. Since T(E) is strongly affected by quantum interference (QI), three manifestations of QI in single-molecules are discussed, namely Mach-Zehnder interferometry, Breit-Wigner resonances and Fano resonances. A simple MATLAB code is provided, which allows the novice reader to explore QI in multi-branched structures described by a tight-binding (Hückel) Hamiltonian. More generally, the strengths and limitations of materials-specific <span class="hlt">transport</span> modelling based on density functional theory are discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016ApPhL.109o2904O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016ApPhL.109o2904O"><span id="translatedtitle"><span class="hlt">Electron</span> <span class="hlt">transport</span> and dielectric breakdown in silicon nitride using a charge <span class="hlt">transport</span> model</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ogden, Sean P.; Lu, Toh-Ming; Plawsky, Joel L.</p> <p>2016-10-01</p> <p>Silicon nitride is an important material used in the <span class="hlt">electronics</span> industry. As such, the <span class="hlt">electronic</span> <span class="hlt">transport</span> and reliability of these materials are important to study and understand. We report on a charge <span class="hlt">transport</span> model to predict leakage current and failure trends based on previously published data for a stoichiometric silicon nitride dielectric. Failure occurs when the defect density increases to a critical value of approximately 6 × 1025 traps/m3. The model's parameters are determined using voltage ramp data only, and yet, the model is also able to predict constant voltage stress failure over a time scale ranging from minutes to months. The successful fit of the model to the experimental data validates our assumption that the dominant defect in the dielectric is the Si dangling bond, located approximately 2.2 eV below the conduction band. A comparison with previous SiCOH simulations shows SiN and SiCOH have similar defect-related material properties. It is also speculated that, based on the estimated parameter values of 2.75 eV for the defect formation activation energy, the materials' TDDB wear-out are caused by broken Si-H bonds, resulting in Si dangling bond defects.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2011APS..SHK.Q5005B&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2011APS..SHK.Q5005B&link_type=ABSTRACT"><span id="translatedtitle">Probing Warm Dense Matter <span class="hlt">electronic</span> structure using X-ray <span class="hlt">absorption</span> Near Edge Spectroscopy (XANES)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Benuzzi Mounaix, Alessandra</p> <p>2011-06-01</p> <p>The behavior and physical properties of warm dense matter, fundamental for various branches of physics including planetology and Inertial Confinement Fusion, are non trivial to simulate either theoretically, numerically or experimentally. Despite important progress obtained in the last decade on macroscopic characterization (e.g. equations of state), microscopic studies are today necessary to investigate finely the WDM structure changes, the phase transitions and to test physical hypothesis and approximations commonly used in calculations. In this work, highly compressed aluminum has been investigated with the aim of bringing information on the evolution of its <span class="hlt">electronic</span> structure by using K-edge shift and XANES. The experiment was performed at LULI laboratory where we used one long pulse (500 ps, IL ~ 8 1013 W/cm2) to create a uniform shock and a second ps beam (IL ~ 1017 W/cm2) to generate an ultra-short broadband X-ray source near the Al K-edge. The spectra were registered by using two conical KAP Bragg crystals. The main target was designed to probe the Aluminum in reshocked conditions allowing us to probe and to test theories in an extreme regime up to now unexplored (ρ ~ 3 ρ0 and T ~ 8 eV). The hydrodynamical Al conditions were measured by using VISARs interferometers and self-emission diagnostics. By increasing the delay between the two beams, we have been able to observe the modification of <span class="hlt">absorption</span> spectra for unloading Al conditions (ρ >= 0.5 g/cc), and to put in evidence the relocalization of the 3p valence <span class="hlt">electrons</span> occurring in the metal-non metal transition. All data have been compared to ab initio and dense plasma calculations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/7097199','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/7097199"><span id="translatedtitle">Analysis of long-range bullet entrance holes by atomic <span class="hlt">absorption</span> spectrophotometry and scanning <span class="hlt">electron</span> microscopy.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ravreby, M</p> <p>1982-01-01</p> <p>Bullet residue and primer particles were analyzed by scanning <span class="hlt">electron</span> microscopy with energy dispersive analysis (SEM-EDA) and by flame and flameless atomic <span class="hlt">absorption</span> spectrophotometry (AAS). The residue and particles were on cloth targets around entrance holes produced by bullets fired at distances of 10 to 200 m. Primer particles and their chemical constituents were almost always detected by SEM-EDA around the holes produced by rifles and pistols fired at long ranges, and in many cases the barium and antimony associated with primer particles were detected by flameless AAS. Particles were also detected by SEM-EDA on the rear of bullets fired into and recovered from wooden blocks. Usually a hole caused by a bullet jacketed with gilding metal could be distinguished from one caused by a bullet jacketed with yellow brass alloy. Paint from bullet tips of military tracers was also detected. Analysis of the various residues around entrance holes provides a means for identifying the type of ammunition used. PMID:7097199</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/pages/biblio/1213049-attosecond-transient-absorption-probing-electronic-superpositions-bound-states-neon-detection-quantum-beats','SCIGOV-DOEP'); return false;" href="http://www.osti.gov/pages/biblio/1213049-attosecond-transient-absorption-probing-electronic-superpositions-bound-states-neon-detection-quantum-beats"><span id="translatedtitle">Attosecond transient <span class="hlt">absorption</span> probing of <span class="hlt">electronic</span> superpositions of bound states in neon. Detection of quantum beats</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Beck, Annelise R; Bernhardt, Birgitta; Warrick, Erika R.; Wu, Mengxi; Chen, Shaohao; Gaarde, Mette B.; Schafer, Kenneth J.; Neumark, Daniel M.; Leone, Stephen R.</p> <p>2014-11-07</p> <p><span class="hlt">Electronic</span> wavepackets composed of multiple bound excited states of atomic neon lying between 19.6 and 21.5 eV are launched using an isolated attosecond pulse. Individual quantum beats of the wavepacket are detected by perturbing the induced polarization of the medium with a time-delayed few-femtosecond near-infrared (NIR) pulse via coupling the individual states to multiple neighboring levels. All of the initially excited states are monitored simultaneously in the attosecond transient <span class="hlt">absorption</span> spectrum, revealing Lorentzian to Fano lineshape spectral changes as well as quantum beats. The most prominent beating of the several that were observed was in the spin–orbit split 3d absorptionmore » features, which has a 40 femtosecond period that corresponds to the spin–orbit splitting of 0.1 eV. The few-level models and multilevel calculations confirm that the observed magnitude of oscillation depends strongly on the spectral bandwidth and tuning of the NIR pulse and on the location of possible coupling states.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1990PhRvB..41..947J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1990PhRvB..41..947J"><span id="translatedtitle">Theory of the <span class="hlt">electronic</span> states and <span class="hlt">absorption</span> spectrum of the LiCl:Ag+ impurity system</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jackson, Koblar A.; Lin, Chun C.</p> <p>1990-01-01</p> <p>The impurity <span class="hlt">absorption</span> spectra of Ag+ and Cu+ impurities in alkali halide hosts show characteristically different features, despite the similar nature of the corresponding free ions. We use the self-interaction-corrected local-spin-density (SIC-LSD) theory to calculate the <span class="hlt">electronic</span> structure of the ground state (4d) and the 5s and 5p excited states of the LiCl:Ag+ impurity ion. The method of linear combinations of atomic orbitals is used to determine the wave functions and energy levels. By comparing with previous calculations for LiCl:Cu+, we are able to attribute the differences in the d-->s and d-->p transitions in the ultraviolet spectra of these systems to the increased bonding between host crystal and impurity orbitals in LiCl:Ag+, due to the more extensive nature of the Ag+ 4d orbitals. A modification of the earlier SIC-LSD impurity-crystal procedure is introduced to treat the strongly mixed impurity states.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003APS..MARB29007Q','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003APS..MARB29007Q"><span id="translatedtitle"><span class="hlt">Electronic</span> Structure of Manganites Determined by Spin-Polarized X-Ray <span class="hlt">Absorption</span> Spectroscopy</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Qian, Qing; Tyson, Trevor; Savrassov, S.; Kao, C.-C.; Croft, M.</p> <p>2003-03-01</p> <p>A systematic study of spin dependent Mn K-edge x-ray <span class="hlt">absorption</span> spectra was performed on La_1-xCa_xMnO3 and other Mn oxide systems. A model was developed to predict the temperature dependent changes in the local magnetic ordering based on changes in spin-polarized Mn K-Edge measurements. With this model, one can ascertain the change of local ordering that occurs on transiting the magnetic ordering temperature. Parallel LDA and LDA+U computations are used to label the symmetries of the unoccupied bands, determine the degree of <span class="hlt">electron</span> correlation and to provide a direct comparison with the band ordering predicted by the temperature dependent spin-polarized measurements. The spin magnetic moment and ordering of the t_2g and eg states are also determined. We find that the occupied t_2g orbitals are always ordered with lobes near 45° to the local Mn-O directions. The Mn K-Edge main line splitting is discussed in terms of the effective spin-polarized charge density. Comparison with bandstructure computations are made. The oxygen hole contribution to the net magnetic moment is seen to be important. We survey the spin-polarized XANES spectra of a large group of manganese oxides showing the general trends in the main line spin splitting as a function of valence. This work is supported by NSF Career Grant DMR-9733862 and DMR-0216858.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19900018892','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19900018892"><span id="translatedtitle">On the relation between the <span class="hlt">electron</span> content of the ionospheric D-region, variations of the riometer <span class="hlt">absorption</span>, and the H-component of the geomagnetic field</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Zelenkova, L. V.; Soldatov, V. A.; Arkhipov, J. V.; Laikova, V. F.</p> <p>1989-01-01</p> <p>The correlation between lower ionosphere disturbances, geomagnetic variations and radiowave <span class="hlt">absorption</span> is an important geophysical problem. The correlation is investigated between the <span class="hlt">electron</span> density profile structure and riometer <span class="hlt">absorption</span>, and between the <span class="hlt">absorption</span> and the H-component magnetic field, in order to determine the relation between the (e)-profile parameters and the geomagnetic field variations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1998JAP....83.3207B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1998JAP....83.3207B"><span id="translatedtitle"><span class="hlt">Electron</span> <span class="hlt">transport</span> across metal/discotic liquid crystal interfaces</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Boden, N.; Bushby, R. J.; Clements, J.; Movaghar, B.</p> <p>1998-03-01</p> <p><span class="hlt">Electron</span> <span class="hlt">transport</span> across micron thick films of columnar hexagonal discotic liquid crystal phases homeotropically aligned between metal electrode surfaces has been studied both experimentally and theoretically. These molecules are unique in their combination of charge <span class="hlt">transport</span> along individual molecular columns with liquidlike self-organization. Typical of organic insulators, a high resistance Ohmic regime is evident at fields of less than 0.05 MV cm-1, due to a low concentration of chemical impurities (n<109cm-3), and a space-charge injection regime at higher fields. Breakdown fields are reasonably high: in hexakis(hexyloxy)triphenylene they reach ˜5 MV cm-1 at room temperature. Our results show that triphenylene-based discotics form an excellent class of highly ordered optically transparent insulators. At high temperatures and high fields the current is injection controlled and exhibits typical tunneling and space charge limited, nonlinear I-V characteristics. Dramatic jumps in injection currents are observed at phase transitions. The change at the crystalline to liquid crystalline phase transition is mainly due to more efficient "wetting" of the electrode surface in the liquid crystalline phase, whilst at the liquid crystalline to isotropic phase transition it arises from the enhancement in the molecular mobility. The concepts of semiconducting gaps, band mobilities, and carrier injection rates are extended to these new materials. The experimental observations are interpreted in a framework which takes into account the important role played by liquidlike dynamics in establishing the microscopic structural order in, what is, otherwise a highly anisotropic and weakly bonded "molecular crystal."</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002PhDT........72B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002PhDT........72B"><span id="translatedtitle">Nonlinear quantum <span class="hlt">transport</span> in low-dimensional <span class="hlt">electronic</span> devices</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Barrios, Andres Javier</p> <p></p> <p>The study of <span class="hlt">transport</span> processes in low-dimensional semiconductors requires a rigorous quantum mechanical treatment. However, a full-fledged quantum <span class="hlt">transport</span> theory of <span class="hlt">electrons</span> (or holes) in semiconductors of small scale, applicable in the presence of external fields of arbitrary strength, is still not available. In the literature, different approaches have been proposed, including: (a) the semiclassical Boltzmann equation, (b) perturbation theory based on Keldysh's Green functions, and (c) the Quantum Boltzmann Equation (QBE), previously derived by Van Vliet and coworkers, applicable in the realm of Kubo's Linear Response Theory (LRT). In the present work, we follow the method originally proposed by Van Wet in LRT. The Hamiltonian in this approach is of the form: H = H 0(E, B) + lambdaV, where H0 contains the externally applied fields, and lambdaV includes many-body interactions. This Hamiltonian differs from the LRT Hamiltonian, H = H0 - AF(t) + lambdaV, which contains the external field in the field-response part, -AF(t). For the nonlinear problem, the eigenfunctions of the system Hamiltonian, H0(E, B), include the external fields without any limitation on strength. In Part A of this dissertation, both the diagonal and nondiagonal Master equations are obtained after applying projection operators to the von Neumann equation for the density operator in the interaction picture, and taking the Van Hove limit, (lambda → 0, t → infinity, so that (lambda2 t)n remains finite). Similarly, the many-body current operator J is obtained from the Heisenberg equation of motion. In Part B, the Quantum Boltzmann Equation is obtained in the occupation-number representation for an <span class="hlt">electron</span> gas, interacting with phonons or impurities. On the one-body level, the current operator obtained in Part A leads to the Generalized Calecki current for electric and magnetic fields of arbitrary strength. Furthermore, in this part, the LRT results for the current and conductance are</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/27027922','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/27027922"><span id="translatedtitle">Tunable Microwave <span class="hlt">Absorption</span> Frequency by Aspect Ratio of Hollow Polydopamine@α-MnO2 Microspindles Studied by <span class="hlt">Electron</span> Holography.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>She, Wen; Bi, Han; Wen, Zhiwei; Liu, Qinghe; Zhao, Xuebing; Zhang, Jie; Che, Renchao</p> <p>2016-04-20</p> <p>A tunable response frequency is highly desirable for practical applications of microwave <span class="hlt">absorption</span> materials but remains a great challenge. Here, hollow lightweight polydopamine@α-MnO2 microspindles were facilely synthesized with the tunable <span class="hlt">absorption</span> frequency governed by the aspect ratio. The size of the hard template is a key factor to achieve the unique shape; the polymer layer with uniform thickness plays an important role in obtaining spindles with homogeneous size. With the aspect ratio increasing, the maximum reflection loss, as well as the <span class="hlt">absorption</span> bandwidth (<-10 dB), increases and then decreases; meanwhile, the microwave <span class="hlt">absorption</span> band shifts to the low frequency. The optimized aspect ratio of the cavity about the hollow polydopamine@α-MnO2 microspindles is ∼2.8. With 3 mm thickness at 9.7 GHz, the strongest reflection reaches -21.8 dB, and the width of the absorbing band (<-10 dB) is as wide as 3.3 GHz. Via <span class="hlt">electron</span> holography, it is confirmed that strong charge accumulates around the interface between the polydopamine and α-MnO2 layers, which mainly contributes to the dielectric polarization <span class="hlt">absorption</span>. This study proposes a reliable strategy to tune the <span class="hlt">absorption</span> frequency via different aspect ratio polymer@α-MnO2 microspindles. PMID:27027922</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1999AcSpA..55.2513C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1999AcSpA..55.2513C"><span id="translatedtitle">Interaction of chlorpromazine and trifluoperazine with ionic micelles: <span class="hlt">electronic</span> <span class="hlt">absorption</span> spectroscopy studies</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Caetano, Wilker; Tabak, Marcel</p> <p>1999-10-01</p> <p>The characteristics of binding of two phenothiazine antipsychotic drugs, namely, chlorpromazine (CPZ) and trifluoperazine (TFP), to cationic cetyltrimethylammonium chloride (CTAC), zwitterionic N-hexadecyl- N, N-dimethyl-3-ammonio-1-propanesulfonate (HPS), neutral t-octylphenoxypolyethoxyethanol (TRITON X-100) and polyoxyethylene dodecyl ether (Brij-35) micelles were investigated using <span class="hlt">electronic</span> <span class="hlt">absorption</span> spectroscopy. Binding constants Kb and p Ka values of drugs in micelles were estimated using the red shifts of the maximum <span class="hlt">absorption</span> upon alkalization or in the presence of detergents. The p Ka of TFP seems to be shifted by 2.5-4.1 units to lower values in the presence of different surfactants as compared to the experimental value of p Ka obtained in buffer which is around 7.0. Consideration of the second p Ka around 4.0 reported in the literature for TFP leads to a better rationalization of p Ka changes for this compound. The changes in p Ka contributed by electrostatic effects are all positive, small for CTAC (+0.2), and greater for HPS (+0.9). For CPZ the p Ka shift due to its interaction with micelles is in the 0.7-2.3 range, the direction of the shift depending on the charge of the polar head. The electrostatic contribution for the shift is great for CTAC (-0.8) and smaller for HPS (+0.2). This result suggests a more polar localization in the micelle of CPZ as compared to TFP. The values of binding constants Kb for TFP and CPZ in different protonation states show that electrostatic interactions are essential in the affinity of the drugs to micelles bearing different charges on their headgroups (CTAC, HPS). Data for Brij-35 demonstrate that the additional charge on the TFP ring at pH 2.0 leads to a decrease of binding constant probably due to the repulsion of the phenothiazine ring from the protons accumulated at the polar head of the micelle at acidic pH values. For this micelle at pH 5.0 TFP has a Kb 3-fold greater than that for CPZ while at pH 2.0 Kb for</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016Nanot..27H5503P&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016Nanot..27H5503P&link_type=ABSTRACT"><span id="translatedtitle">Surface trap mediated <span class="hlt">electronic</span> <span class="hlt">transport</span> in biofunctionalized silicon nanowires</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Puppo, F.; Traversa, F. L.; Di Ventra, M.; De Micheli, G.; Carrara, S.</p> <p>2016-08-01</p> <p>Silicon nanowires (SiNWs), fabricated via a top-down approach and then functionalized with biological probes, are used for electrically-based sensing of breast tumor markers. The SiNWs, featuring memristive-like behavior in bare conditions, show, in the presence of biomarkers, modified hysteresis and, more importantly, a voltage memory component, namely a voltage gap. The voltage gap is demonstrated to be a novel and powerful parameter of detection thanks to its high-resolution dependence on charges in proximity of the wire. This unique approach of sensing has never been studied and adopted before. Here, we propose a physical model of the surface <span class="hlt">electronic</span> <span class="hlt">transport</span> in Schottky barrier SiNW biosensors, aiming at reproducing and understanding the voltage gap based behavior. The implemented model describes well the experimental I–V characteristics of the device. It also links the modification of the voltage gap to the changing concentration of antigens by showing the decrease of this parameter in response to increasing concentrations of the molecules that are detected with femtomolar resolution in real human samples. Both experiments and simulations highlight the predominant role of the dynamic recombination of the nanowire surface states, with the incoming external charges from bio-species, in the appearance and modification of the voltage gap. Finally, thanks to its compactness, and strict correlation with the physics of the nanodevice, this model can be used to describe and predict the I–V characteristics in other nanostructured devices, for different than antibody-based sensing as well as <span class="hlt">electronic</span> applications.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27418560','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27418560"><span id="translatedtitle">Surface trap mediated <span class="hlt">electronic</span> <span class="hlt">transport</span> in biofunctionalized silicon nanowires.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Puppo, F; Traversa, F L; Ventra, M Di; Micheli, G De; Carrara, S</p> <p>2016-08-26</p> <p>Silicon nanowires (SiNWs), fabricated via a top-down approach and then functionalized with biological probes, are used for electrically-based sensing of breast tumor markers. The SiNWs, featuring memristive-like behavior in bare conditions, show, in the presence of biomarkers, modified hysteresis and, more importantly, a voltage memory component, namely a voltage gap. The voltage gap is demonstrated to be a novel and powerful parameter of detection thanks to its high-resolution dependence on charges in proximity of the wire. This unique approach of sensing has never been studied and adopted before. Here, we propose a physical model of the surface <span class="hlt">electronic</span> <span class="hlt">transport</span> in Schottky barrier SiNW biosensors, aiming at reproducing and understanding the voltage gap based behavior. The implemented model describes well the experimental I-V characteristics of the device. It also links the modification of the voltage gap to the changing concentration of antigens by showing the decrease of this parameter in response to increasing concentrations of the molecules that are detected with femtomolar resolution in real human samples. Both experiments and simulations highlight the predominant role of the dynamic recombination of the nanowire surface states, with the incoming external charges from bio-species, in the appearance and modification of the voltage gap. Finally, thanks to its compactness, and strict correlation with the physics of the nanodevice, this model can be used to describe and predict the I-V characteristics in other nanostructured devices, for different than antibody-based sensing as well as <span class="hlt">electronic</span> applications.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016Nanot..27H5503P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016Nanot..27H5503P"><span id="translatedtitle">Surface trap mediated <span class="hlt">electronic</span> <span class="hlt">transport</span> in biofunctionalized silicon nanowires</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Puppo, F.; Traversa, F. L.; Di Ventra, M.; De Micheli, G.; Carrara, S.</p> <p>2016-08-01</p> <p>Silicon nanowires (SiNWs), fabricated via a top-down approach and then functionalized with biological probes, are used for electrically-based sensing of breast tumor markers. The SiNWs, featuring memristive-like behavior in bare conditions, show, in the presence of biomarkers, modified hysteresis and, more importantly, a voltage memory component, namely a voltage gap. The voltage gap is demonstrated to be a novel and powerful parameter of detection thanks to its high-resolution dependence on charges in proximity of the wire. This unique approach of sensing has never been studied and adopted before. Here, we propose a physical model of the surface <span class="hlt">electronic</span> <span class="hlt">transport</span> in Schottky barrier SiNW biosensors, aiming at reproducing and understanding the voltage gap based behavior. The implemented model describes well the experimental I-V characteristics of the device. It also links the modification of the voltage gap to the changing concentration of antigens by showing the decrease of this parameter in response to increasing concentrations of the molecules that are detected with femtomolar resolution in real human samples. Both experiments and simulations highlight the predominant role of the dynamic recombination of the nanowire surface states, with the incoming external charges from bio-species, in the appearance and modification of the voltage gap. Finally, thanks to its compactness, and strict correlation with the physics of the nanodevice, this model can be used to describe and predict the I-V characteristics in other nanostructured devices, for different than antibody-based sensing as well as <span class="hlt">electronic</span> applications.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active"><span>21</span></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_21 --> <div id="page_22" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li class="active"><span>22</span></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="421"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/22341856','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22341856"><span id="translatedtitle">Study of <span class="hlt">electronic</span> <span class="hlt">transport</span> in gamma ray exposed nanowires</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Gehlawat, Devender Chauhan, R.P.</p> <p>2014-01-01</p> <p>Graphical abstract: A sharp decline in the I–V characteristics of Cu (and Cd) nanowires was experimentally observed after the gamma ray exposure of nanowires. Irradiation induced transformations in the granular properties and the resonance state of electron–phonon coupling beyond a particular value of external field may be accountable for observed shape of I–V characteristics in gamma ray exposed nanowires. - Highlights: • Cu and Cd nanowires were synthesized by technique of electrodeposition in templates. • The nanowires were exposed to different doses of gamma ray photons. • A sharp decline in the current in I–V characteristics (IVC) was observed. • Structural deviation in terms of granular orientations was also analysed. • The electron–phonon coupling may be responsible for observed sharp decline in IVC. - Abstract: One dimensional nanostructures provide the most restricted and narrow channel for the <span class="hlt">transport</span> of charge carriers and therefore 1D structures preserve their significance from the viewpoint of <span class="hlt">electronic</span> devices. The net radiation effect on nanomaterials is expected to be more (due to their increased reactivity and lesser bulk volume) than their bulk counterparts. Radiation often modifies the structure and simultaneously the other physical properties of materials. In this manner, the irradiation phenomenon could be counted as a strong criterion to induce changes in the structural and electrical properties of nanowires. We have studied the effect of gamma rays on the <span class="hlt">electronic</span> flow through Cu and Cd nanowires by plotting their I–V characteristics (IVC). The IVC of gamma ray exposed nanowires was found to be a combination of the linear and nonlinear regions and a decreasing pattern in the electrical conductivity (calculated from the linear portion of IVC) was observed as we increased the dose of gamma rays.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/27418560','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/27418560"><span id="translatedtitle">Surface trap mediated <span class="hlt">electronic</span> <span class="hlt">transport</span> in biofunctionalized silicon nanowires.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Puppo, F; Traversa, F L; Ventra, M Di; Micheli, G De; Carrara, S</p> <p>2016-08-26</p> <p>Silicon nanowires (SiNWs), fabricated via a top-down approach and then functionalized with biological probes, are used for electrically-based sensing of breast tumor markers. The SiNWs, featuring memristive-like behavior in bare conditions, show, in the presence of biomarkers, modified hysteresis and, more importantly, a voltage memory component, namely a voltage gap. The voltage gap is demonstrated to be a novel and powerful parameter of detection thanks to its high-resolution dependence on charges in proximity of the wire. This unique approach of sensing has never been studied and adopted before. Here, we propose a physical model of the surface <span class="hlt">electronic</span> <span class="hlt">transport</span> in Schottky barrier SiNW biosensors, aiming at reproducing and understanding the voltage gap based behavior. The implemented model describes well the experimental I-V characteristics of the device. It also links the modification of the voltage gap to the changing concentration of antigens by showing the decrease of this parameter in response to increasing concentrations of the molecules that are detected with femtomolar resolution in real human samples. Both experiments and simulations highlight the predominant role of the dynamic recombination of the nanowire surface states, with the incoming external charges from bio-species, in the appearance and modification of the voltage gap. Finally, thanks to its compactness, and strict correlation with the physics of the nanodevice, this model can be used to describe and predict the I-V characteristics in other nanostructured devices, for different than antibody-based sensing as well as <span class="hlt">electronic</span> applications. PMID:27418560</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26577021','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26577021"><span id="translatedtitle">Eicosapentaenoic acid inhibits intestinal β-carotene <span class="hlt">absorption</span> by downregulation of lipid <span class="hlt">transporter</span> expression via PPAR-α dependent mechanism.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Mashurabad, Purna Chandra; Kondaiah, Palsa; Palika, Ravindranadh; Ghosh, Sudip; Nair, Madhavan K; Raghu, Pullakhandam</p> <p>2016-01-15</p> <p>The involvement of lipid <span class="hlt">transporters</span>, the scavenger receptor class B, type I (SR-BI) and Niemann-Pick type C1 Like 1 protein (NPC1L1) in carotenoid <span class="hlt">absorption</span> is demonstrated in intestinal cells and animal models. Dietary ω-3 fatty acids are known to possess antilipidemic properties, which could be mediated by activation of PPAR family transcription factors. The present study was conducted to determine the effect of docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), on intestinal β-carotene <span class="hlt">absorption</span>. β-carotene uptake in Caco-2/TC7 cells was inhibited by EPA (p < 0.01) and PPARα agonist (P < 0.01), but not by DHA, PPARγ or PPARδ agonists. Despite unaltered β-carotene uptake, both DHA and PPARδ agonists inhibited the NPC1L1 expression. Further, EPA also induced the expression of carnitine palmitoyl transferase 1A (CPT1A) expression, a PPARα target gene. Interestingly, EPA induced inhibition of β-carotene uptake and SR B1 expression were abrogated by specific PPARα antagonist, but not by PPARδ antagonist. EPA and PPARα agonist also inhibited the basolateral secretion of β-carotene from Caco-2 cells grown on permeable supports. These results suggest that EPA inhibits intestinal β-carotene <span class="hlt">absorption</span> by down regulation of SR B1 expression via PPARα dependent mechanism and provide an evidence for dietary modulation of intestinal β-carotene <span class="hlt">absorption</span>. PMID:26577021</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26577021','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26577021"><span id="translatedtitle">Eicosapentaenoic acid inhibits intestinal β-carotene <span class="hlt">absorption</span> by downregulation of lipid <span class="hlt">transporter</span> expression via PPAR-α dependent mechanism.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Mashurabad, Purna Chandra; Kondaiah, Palsa; Palika, Ravindranadh; Ghosh, Sudip; Nair, Madhavan K; Raghu, Pullakhandam</p> <p>2016-01-15</p> <p>The involvement of lipid <span class="hlt">transporters</span>, the scavenger receptor class B, type I (SR-BI) and Niemann-Pick type C1 Like 1 protein (NPC1L1) in carotenoid <span class="hlt">absorption</span> is demonstrated in intestinal cells and animal models. Dietary ω-3 fatty acids are known to possess antilipidemic properties, which could be mediated by activation of PPAR family transcription factors. The present study was conducted to determine the effect of docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), on intestinal β-carotene <span class="hlt">absorption</span>. β-carotene uptake in Caco-2/TC7 cells was inhibited by EPA (p < 0.01) and PPARα agonist (P < 0.01), but not by DHA, PPARγ or PPARδ agonists. Despite unaltered β-carotene uptake, both DHA and PPARδ agonists inhibited the NPC1L1 expression. Further, EPA also induced the expression of carnitine palmitoyl transferase 1A (CPT1A) expression, a PPARα target gene. Interestingly, EPA induced inhibition of β-carotene uptake and SR B1 expression were abrogated by specific PPARα antagonist, but not by PPARδ antagonist. EPA and PPARα agonist also inhibited the basolateral secretion of β-carotene from Caco-2 cells grown on permeable supports. These results suggest that EPA inhibits intestinal β-carotene <span class="hlt">absorption</span> by down regulation of SR B1 expression via PPARα dependent mechanism and provide an evidence for dietary modulation of intestinal β-carotene <span class="hlt">absorption</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27146607','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27146607"><span id="translatedtitle"><span class="hlt">Electronic</span> defect states at the LaAlO3/SrTiO3 heterointerface revealed by O K-edge X-ray <span class="hlt">absorption</span> spectroscopy.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Palina, Natalia; Annadi, Anil; Asmara, Teguh Citra; Diao, Caozheng; Yu, Xiaojiang; Breese, Mark B H; Venkatesan, T; Ariando; Rusydi, Andrivo</p> <p>2016-05-18</p> <p>Interfaces of two dissimilar complex oxides exhibit exotic physical properties that are absent in their parent compounds. Of particular interest is insulating LaAlO3 films on an insulating SrTiO3 substrate, where <span class="hlt">transport</span> measurements have shown a metal-insulator transition as a function of LaAlO3 thickness. Their origin has become the subject of intense research, yet a unifying consensus remains elusive. Here, we report evidence for the <span class="hlt">electronic</span> reconstruction in both insulating and conducting LaAlO3/SrTiO3 heterointerfaces revealed by O K-edge X-ray <span class="hlt">absorption</span> spectroscopy. For the insulating samples, the O K-edge XAS spectrum exhibits features characteristic of <span class="hlt">electronically</span> active point defects identified as noninteger valence states of Ti. For conducting samples, a new shape-resonance at ∼540.5 eV, characteristic of molecular-like oxygen (empty O-2p band), is observed. This implies that the concentration of <span class="hlt">electronic</span> defects has increased in proportion with LaAlO3 thickness. For larger defect concentrations, the <span class="hlt">electronic</span> defect states are no longer localized at the Ti orbitals and exhibit pronounced O 2p-O 2p character. Our results demonstrate that, above a critical thickness, the delocalization of O 2p <span class="hlt">electronic</span> states can be linked to the presence of oxygen vacancies and is responsible for the enhancement of conductivity at the oxide heterointerfaces.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016NatSR...627049F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016NatSR...627049F"><span id="translatedtitle">Defect engineering of the <span class="hlt">electronic</span> <span class="hlt">transport</span> through cuprous oxide interlayers</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fadlallah, Mohamed M.; Eckern, Ulrich; Schwingenschlögl, Udo</p> <p>2016-06-01</p> <p>The <span class="hlt">electronic</span> <span class="hlt">transport</span> through Au–(Cu2O)n–Au junctions is investigated using first-principles calculations and the nonequilibrium Green’s function method. The effect of varying the thickness (i.e., n) is studied as well as that of point defects and anion substitution. For all Cu2O thicknesses the conductance is more enhanced by bulk-like (in contrast to near-interface) defects, with the exception of O vacancies and Cl substitutional defects. A similar transmission behavior results from Cu deficiency and N substitution, as well as from Cl substitution and N interstitials for thick Cu2O junctions. In agreement with recent experimental observations, it is found that N and Cl doping enhances the conductance. A Frenkel defect, i.e., a superposition of an O interstitial and O substitutional defect, leads to a remarkably high conductance. From the analysis of the defect formation energies, Cu vacancies are found to be particularly stable, in agreement with earlier experimental and theoretical work.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/6067021','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/6067021"><span id="translatedtitle">Considerations of beta and <span class="hlt">electron</span> <span class="hlt">transport</span> in internal dose calculations</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Bolch, W.E.; Poston, J.W. Sr. . Dept. of Nuclear Engineering)</p> <p>1990-12-01</p> <p>Ionizing radiation has broad uses in modern science and medicine. These uses often require the calculation of energy deposition in the irradiated media and, usually, the medium of interest is the human body. Energy deposition from radioactive sources within the human body and the effects of such deposition are considered in the field of internal dosimetry. In July of 1988, a three-year research project was initiated by the Nuclear Engineering Department at Texas A M University under the sponsorship of the US Department of Energy. The main thrust of the research was to consider, for the first time, the detailed spatial <span class="hlt">transport</span> of <span class="hlt">electron</span> and beta particles in the estimation of average organ doses under the Medical Internal Radiation Dose (MIRD) schema. At the present time (December of 1990), research activities are continuing within five areas. Several are new initiatives begun within the second or third year of the current contract period. They include: (1) development of small-scale dosimetry; (2) development of a differential volume phantom; (3) development of a dosimetric bone model; (4) assessment of the new ICRP lung model; and (5) studies into the mechanisms of DNA damage. A progress report is given for each of these tasks within the Comprehensive Report. In each use, preliminary results are very encouraging and plans for further research are detailed within this document. 22 refs., 13 figs., 1 tab.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4891735','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4891735"><span id="translatedtitle">Defect engineering of the <span class="hlt">electronic</span> <span class="hlt">transport</span> through cuprous oxide interlayers</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Fadlallah, Mohamed M.; Eckern, Ulrich; Schwingenschlögl, Udo</p> <p>2016-01-01</p> <p>The <span class="hlt">electronic</span> <span class="hlt">transport</span> through Au–(Cu2O)n–Au junctions is investigated using first-principles calculations and the nonequilibrium Green’s function method. The effect of varying the thickness (i.e., n) is studied as well as that of point defects and anion substitution. For all Cu2O thicknesses the conductance is more enhanced by bulk-like (in contrast to near-interface) defects, with the exception of O vacancies and Cl substitutional defects. A similar transmission behavior results from Cu deficiency and N substitution, as well as from Cl substitution and N interstitials for thick Cu2O junctions. In agreement with recent experimental observations, it is found that N and Cl doping enhances the conductance. A Frenkel defect, i.e., a superposition of an O interstitial and O substitutional defect, leads to a remarkably high conductance. From the analysis of the defect formation energies, Cu vacancies are found to be particularly stable, in agreement with earlier experimental and theoretical work. PMID:27256905</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/pages/biblio/1200859-electronic-transport-two-dimensional-high-dielectric-constant-nanosystems','SCIGOV-DOEP'); return false;" href="http://www.osti.gov/pages/biblio/1200859-electronic-transport-two-dimensional-high-dielectric-constant-nanosystems"><span id="translatedtitle"><span class="hlt">Electronic</span> <span class="hlt">transport</span> in two-dimensional high dielectric constant nanosystems</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Ortuño, M.; Somoza, A. M.; Vinokur, V. M.; Baturina, T. I.</p> <p>2015-04-10</p> <p>There has been remarkable recent progress in engineering high-dielectric constant two dimensional (2D) materials, which are being actively pursued for applications in nanoelectronics in capacitor and memory devices, energy storage, and high-frequency modulation in communication devices. Yet many of the unique properties of these systems are poorly understood and remain unexplored. Here we report a numerical study of hopping conductivity of the lateral network of capacitors, which models two-dimensional insulators, and demonstrate that 2D long-range Coulomb interactions lead to peculiar size effects. We find that the characteristic energy governing <span class="hlt">electronic</span> <span class="hlt">transport</span> scales logarithmically with either system size or electrostatic screeningmore » length depending on which one is shorter. Our results are relevant well beyond their immediate context, explaining, for example, recent experimental observations of logarithmic size dependence of electric conductivity of thin superconducting films in the critical vicinity of superconductor-insulator transition where a giant dielectric constant develops. Our findings mark a radical departure from the orthodox view of conductivity in 2D systems as a local characteristic of materials and establish its macroscopic global character as a generic property of high-dielectric constant 2D nanomaterials.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005PhDT........42Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005PhDT........42Y"><span id="translatedtitle"><span class="hlt">Electronic</span> <span class="hlt">transport</span> of N-type semiconductor nanocrystalline solids</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yu, Dong</p> <p>2005-07-01</p> <p>A bottleneck limiting the widespread applications of semiconductor nanocrystalline solids on optoelectronic devices such as photovoltaic cells, light emitting devices and quantum dots lasers is their poor conductivity. In this thesis, we show that the conductivity of thin films of CdSe nanocrystals is increased by many orders of magnitude when n-doped either by potassium or electrochemistry. Around half-filling of the first <span class="hlt">electronic</span> shell, a peak in the conductivity is observed indicating shell to shell <span class="hlt">transport</span>. Introducing conjugated ligands between nanocrystals increases the conductivities to ˜10-2 S cm. NaOH treatment of the thin films leads to a large carrier mobility and a semiconductor nanocrystals field effect transistor is produced. The temperature and electrical field dependent conductivity of n-type CdSe nanocrystal thin films is then investigated. The low field conductivity follows exp(-(T*/T)-1/2 ) and high field conductivity follows exp(-(E*/ E)-1/2). The complete behavior is very well described by the variable range hopping theory with a Coulomb gap. Finally, n-type colloidal CdSe nanocrystalline solids show large positive magnetoresistance at low temperatures (0.3K--4K). We attempted to dope Manganese (II) ions in nanocrystals, which might show interesting negative magnetoresistance. However, they still show similar positive magnetoresistance probably due to the difficulty of Mn doping. At ˜0.3K the resistance is increased by ˜150% at 10 Tesla.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/6067078','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/6067078"><span id="translatedtitle">Considerations of beta and <span class="hlt">electron</span> <span class="hlt">transport</span> in internal dose calculations</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Bolch, W.E.; Poston, J.W. Sr.</p> <p>1990-12-01</p> <p>Ionizing radiation has broad uses in modern science and medicine. These uses often require the calculation of energy deposition in the irradiated media and, usually, the medium of interest is the human body. Energy deposition from radioactive sources within the human body and the effects of such deposition are considered in the field of internal dosimetry. In July of 1988, a three-year research project was initiated by the Nuclear Engineering Department at Texas A M University under the sponsorship of the US Department of Energy. The main thrust of the research was to consider, for the first time, the detailed spatial <span class="hlt">transport</span> of <span class="hlt">electron</span> and beta particles in the estimation of average organ doses under the Medical Internal Radiation Dose (MIRD) schema. At the present time (December of 1990), research activities are continuing within five areas. Several are new initiatives begun within the second or third year of the current contract period. They include: (1) development of small-scale dosimetry; (2) development of a differential volume phantom; (3) development of a dosimetric bone model; (4) assessment of the new ICRP lung model; and (5) studies into the mechanisms of DNA damage. A progress report is given for each of these tasks within the Comprehensive Report. In each case, preliminary results are very encouraging and plans for further research are detailed within this document.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015NatSR...5E9667O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015NatSR...5E9667O"><span id="translatedtitle"><span class="hlt">Electronic</span> <span class="hlt">transport</span> in two-dimensional high dielectric constant nanosystems</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ortuño, M.; Somoza, A. M.; Vinokur, V. M.; Baturina, T. I.</p> <p>2015-04-01</p> <p>There has been remarkable recent progress in engineering high-dielectric constant two dimensional (2D) materials, which are being actively pursued for applications in nanoelectronics in capacitor and memory devices, energy storage, and high-frequency modulation in communication devices. Yet many of the unique properties of these systems are poorly understood and remain unexplored. Here we report a numerical study of hopping conductivity of the lateral network of capacitors, which models two-dimensional insulators, and demonstrate that 2D long-range Coulomb interactions lead to peculiar size effects. We find that the characteristic energy governing <span class="hlt">electronic</span> <span class="hlt">transport</span> scales logarithmically with either system size or electrostatic screening length depending on which one is shorter. Our results are relevant well beyond their immediate context, explaining, for example, recent experimental observations of logarithmic size dependence of electric conductivity of thin superconducting films in the critical vicinity of superconductor-insulator transition where a giant dielectric constant develops. Our findings mark a radical departure from the orthodox view of conductivity in 2D systems as a local characteristic of materials and establish its macroscopic global character as a generic property of high-dielectric constant 2D nanomaterials.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1200859','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1200859"><span id="translatedtitle"><span class="hlt">Electronic</span> <span class="hlt">transport</span> in two-dimensional high dielectric constant nanosystems</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Ortuño, M.; Somoza, A. M.; Vinokur, V. M.; Baturina, T. I.</p> <p>2015-04-10</p> <p>There has been remarkable recent progress in engineering high-dielectric constant two dimensional (2D) materials, which are being actively pursued for applications in nanoelectronics in capacitor and memory devices, energy storage, and high-frequency modulation in communication devices. Yet many of the unique properties of these systems are poorly understood and remain unexplored. Here we report a numerical study of hopping conductivity of the lateral network of capacitors, which models two-dimensional insulators, and demonstrate that 2D long-range Coulomb interactions lead to peculiar size effects. We find that the characteristic energy governing <span class="hlt">electronic</span> <span class="hlt">transport</span> scales logarithmically with either system size or electrostatic screening length depending on which one is shorter. Our results are relevant well beyond their immediate context, explaining, for example, recent experimental observations of logarithmic size dependence of electric conductivity of thin superconducting films in the critical vicinity of superconductor-insulator transition where a giant dielectric constant develops. Our findings mark a radical departure from the orthodox view of conductivity in 2D systems as a local characteristic of materials and establish its macroscopic global character as a generic property of high-dielectric constant 2D nanomaterials.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19790049939&hterms=1603&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3D%2526%25231603','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19790049939&hterms=1603&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3D%2526%25231603"><span id="translatedtitle">Optical <span class="hlt">absorption</span> and radiative heat <span class="hlt">transport</span> in olivine at high temperature</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Shankland, T. J.; Nitsan, U.; Duba, A. G.</p> <p>1979-01-01</p> <p>Results are presented of measurements of the optical <span class="hlt">absorption</span> spectra (300-8000 nm) of olivine as a function of temperature (300-1700 K) under conditions of controlled and known oxygen fugacity within the stability field of the samples. The <span class="hlt">absorption</span> spectra are used to calculate the temperature-dependent radiative transfer coefficient of olivine and to numerically study the accuracy of the method. The present <span class="hlt">absorption</span> measurements in olivine under oxidizing conditions known to be within the olivine stability field indicate that the effective radiative conductivity K(R) is lower than that obtained in previous studies under different experimental conditions. The lower value of K(R) makes it more likely that some of the earth's internal heat is removed by convection and less likely that thermal models involving conduction and radiation alone will satisfactorily explain thermal conditions in the earth's mantle.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19990071231','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19990071231"><span id="translatedtitle">Inner Magnetospheric Superthermal <span class="hlt">Electron</span> <span class="hlt">Transport</span>: Photoelectron and Plasma Sheet <span class="hlt">Electron</span> Sources</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Khazanov, G. V.; Liemohn, M. W.; Kozyra, J. U.; Moore, T. E.</p> <p>1998-01-01</p> <p>Two time-dependent kinetic models of superthermal <span class="hlt">electron</span> <span class="hlt">transport</span> are combined to conduct global calculations of the nonthermal <span class="hlt">electron</span> distribution function throughout the inner magnetosphere. It is shown that the energy range of validity for this combined model extends down to the superthermal-thermal intersection at a few eV, allowing for the calculation of the en- tire distribution function and thus an accurate heating rate to the thermal plasma. Because of the linearity of the formulas, the source terms are separated to calculate the distributions from the various populations, namely photoelectrons (PEs) and plasma sheet <span class="hlt">electrons</span> (PSEs). These distributions are discussed in detail, examining the processes responsible for their formation in the various regions of the inner magnetosphere. It is shown that convection, corotation, and Coulomb collisions are the dominant processes in the formation of the PE distribution function and that PSEs are dominated by the interplay between the drift terms. Of note is that the PEs propagate around the nightside in a narrow channel at the edge of the plasmasphere as Coulomb collisions reduce the fluxes inside of this and convection compresses the flux tubes inward. These distributions are then recombined to show the development of the total superthermal <span class="hlt">electron</span> distribution function in the inner magnetosphere and their influence on the thermal plasma. PEs usually dominate the dayside heating, with integral energy fluxes to the ionosphere reaching 10(exp 10) eV/sq cm/s in the plasmasphere, while heating from the PSEs typically does not exceed 10(exp 8) eV/sq cm/s. On the nightside, the inner plasmasphere is usually unheated by superthermal <span class="hlt">electrons</span>. A feature of these combined spectra is that the distribution often has upward slopes with energy, particularly at the crossover from PE to PSE dominance, indicating that instabilities are possible.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/18586352','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/18586352"><span id="translatedtitle">Preservation of photosynthetic <span class="hlt">electron</span> <span class="hlt">transport</span> from senescence-induced inactivation in primary leaves after decapitation and defoliation of bean plants.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Yordanov, Ivan; Goltsev, Vasilij; Stefanov, Detelin; Chernev, Petko; Zaharieva, Ivelina; Kirova, Maria; Gecheva, Velichka; Strasser, Reto Jörg</p> <p>2008-12-01</p> <p>The comparative effects of decapitation and defoliation on the senescence-induced inactivation of photosynthetic activity in primary leaves of bean plants were investigated. Decapitation was performed during different phases of bean plant ontogenesis, immediately after the appearance of the 1st, 2nd, 3rd and 4th composite leaf. In addition, we examined a variant with primary leaves and stem with an apical bud, but without composite leaves, i.e. defoliated plants. Analyses of chlorophyll fluorescence, millisecond delayed fluorescence and <span class="hlt">absorption</span> at 830nm in primary leaves were undertaken to investigate the alterations in photosystems II and I <span class="hlt">electron</span> <span class="hlt">transport</span> during the decapitation-induced delayed senescence in the non-detached leaves. Analysis of the OKJIP transients using the JIP-test (see [Strasser R, Srivastava A, Tsimilli-Michael M. Analysis of the chlorophyll a fluorescence transient. In: Papageorgiou G, Govindjee, editors. Chlorophyll a fluorescence: a signature of photosynthesis. The Netherlands: Kluwer Academic Publishers, 2004; pp. 321-362]) showed an increase in several biophysical parameters of photosystem II in decapitated plants, specifically, the density of active reaction centers on a chlorophyll basis, the yields of trapping and <span class="hlt">electron</span> <span class="hlt">transport</span>, and the performance index. We also observed a decrease in the absorbed light energy per reaction center. Such a decrease in light <span class="hlt">absorption</span> could be a result of the photosystem II down regulation that appeared as an increase in Q(B)-non-reducing photosystem II centers. The effect was identical when all leaves except the primary leaves were removed. The variant with a preserved apical bud, the defoliated plant, showed values similar to those of decapitated plants with primary leaves only. The changes in the induction curves of the delayed fluorescence also indicated an acceleration of <span class="hlt">electron</span> <span class="hlt">transport</span> beyond photosystem II in the decapitated and in defoliated plants. In these plants, the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1986JGR....9113455G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1986JGR....9113455G"><span id="translatedtitle">Correlated <span class="hlt">electron</span> and X ray measurements of quiet time <span class="hlt">electron</span> precipitation - A comparative study of bremsstrahlung production and <span class="hlt">transport</span> in the atmosphere</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gaines, E. E.; Imhof, W. L.; Francis, W. E.; Walt, M.; Rosenberg, T. J.</p> <p>1986-12-01</p> <p>Five cases of X-ray observations from balloons, coordinated with measurements of precipitating <span class="hlt">electrons</span>, were obtained during passes of the polar-orbiting satellite P78-1 near Siple, Antarctica, the launch point of the balloons. The observations, made during a geomagnetically quiet period in late December 1980 to early January 1981, showed small enhancements of the X-ray fluxes (E greater than 25 keV) and moderate trapped <span class="hlt">electron</span> fluxes (E greater than 68 keV) with pitch angle distributions extending into the edge of the loss cone sufficient to produce the less than about 0.5 dB of cosmic noise <span class="hlt">absorption</span> recorded by the Siple 30-MHz riometer. Bremsstrahlung production and <span class="hlt">transport</span> in the atmosphere were calculated using the measured <span class="hlt">electron</span> fluxes, energy spectra, and pitch angle distributions for the source. The X-ray fluxes and spectra calculated for the balloon altitudes were in good agreement with those measured from the balloons when the total energy deposition from <span class="hlt">electrons</span>, E greater than 10 keV, exceeded 0.002 erg/sq cm s. The observed <span class="hlt">electron</span> fluxes show that a significant continuous <span class="hlt">electron</span> precipitation occurs at the western edge of the South Atlantic magnetic anomaly even at times of low geomagnetic activity.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/7021892','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/7021892"><span id="translatedtitle">Correlated <span class="hlt">electron</span> and X ray measurements of quiet time <span class="hlt">electron</span> precipitation: a comparative study of Bremsstrahlung production and <span class="hlt">transport</span> in the atmosphere</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Gaines, E.E.; Imhof, W.L.; Francis, W.E.; Walt, M.; Rosenberg, T.J.</p> <p>1986-12-01</p> <p>Five cases of X ray observations from balloons coordinated with measurements of precipitating <span class="hlt">electrons</span> were obtained during passes of the polar-orbiting satellite P78-1 near Siple, Antarctica (L--4.1), the launch point of the balloons. The observations, made during a geomagnetically quiet period in late December 1980 to early January 1981, showed small enhancements of the X ray fluxes (E>25 keV) and moderate trapped <span class="hlt">electron</span> fluxes (E>68 keV) with pitch angle distributions extending into the edge of the loss cone sufficient to produce the approx. <0.5 dB of cosmic noise <span class="hlt">absorption</span> recorded by the Siple 30-MHz riometer. Bremsstrahlung production and <span class="hlt">transport</span> in the atmosphere were calculated using the measured <span class="hlt">electron</span> fluxes, energy spectra, and pitch angle distributions for the source. The X ray fluxes and spectra calculated for the balloon altitudes were in good agreement with those measured from the balloons when the total energy deposition from <span class="hlt">electrons</span>, E>10 keV, exceeded 2 x 10/sup -3/ erg/cm/sup 2/ s. The observed <span class="hlt">electron</span> fluxes show that a significant continuous <span class="hlt">electron</span> precipitation occurs at the western edge of the South Atlantic magnetic anomaly even at times of low geomagnetic activity.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/319673','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/319673"><span id="translatedtitle"><span class="hlt">Electron</span> heat <span class="hlt">transport</span> in improved confinement discharges in DIII-D</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Stallard, B.W.; Greenfield, C.M.; Staebler, G.M.</p> <p>1999-01-01</p> <p>In DIII-D tokamak plasmas with an internal <span class="hlt">transport</span> barrier (ITB), the comparison of gyrokinetic linear stability (GKS) predictions with experiments in both low and strong negative magnetic shear plasmas provide improved understanding for <span class="hlt">electron</span> thermal <span class="hlt">transport</span> within the plasma. Within a limited region just inside the ITB, the <span class="hlt">electron</span> temperature gradient (ETG) modes appear to control the <span class="hlt">electron</span> temperature gradient and, consequently, the <span class="hlt">electron</span> thermal <span class="hlt">transport</span>. The increase in the <span class="hlt">electron</span> temperature gradient with more strongly negative magnetic shear is consistent with the increase in the ETG mode marginal gradient. Closer to the magnetic axis the T{sub e} profile flattens and the ETG modes are predicted to be stable. With additional core <span class="hlt">electron</span> heating, FIR scattering measurements near the axis show the presence of high k fluctuations (12 cm{sup {minus}1}), rotating in the <span class="hlt">electron</span> diamagnetic drift direction. This turbulence could impact <span class="hlt">electron</span> <span class="hlt">transport</span> and possibly also ion <span class="hlt">transport</span>. Thermal diffusivities for <span class="hlt">electrons</span>, and to a lesser degree ions, increase. The ETG mode can exist at this wavenumber, but it is computed to be robustly stable near the axis. Consequently, in the plasmas the authors have examined, calculations of drift wave linear stability do not explain the observed <span class="hlt">transport</span> near the axis in plasmas with or without additional <span class="hlt">electron</span> heating, and there are probably other processes controlling <span class="hlt">transport</span> in this region.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21189140','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21189140"><span id="translatedtitle">Interplay of metabolism and <span class="hlt">transport</span> in determining oral drug <span class="hlt">absorption</span> and gut wall metabolism: a simulation assessment using the "Advanced Dissolution, <span class="hlt">Absorption</span>, Metabolism (ADAM)" model.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Darwich, A S; Neuhoff, S; Jamei, M; Rostami-Hodjegan, A</p> <p>2010-11-01</p> <p>Bioavailability of orally administered drugs can be influenced by a number of factors including release from the formulation, dissolution, stability in the gastrointestinal (GI) environment, permeability through the gut wall and first-pass gut wall and hepatic metabolism. Although there are various enzymes in the gut wall which may contribute to gut first pass metabolism, Cytochrome P450 (CYP) 3A has been shown to play a major role. The efflux <span class="hlt">transporter</span> P-glycoprotein (P-gp; MDR1/ABCB1) is the most extensively studied drug efflux <span class="hlt">transporter</span> in the gut and might have a significant role in the regulation of GI <span class="hlt">absorption</span>. Although not every CYP3A substrate will have a high extent of gut wall first-pass extraction, being a substrate for the enzyme increases the likelihood of a higher first-pass extraction. Similarly, being a P-gp substrate does not necessarily pose a problem with the gut wall <span class="hlt">absorption</span> however it may reduce bioavailability in some cases (e.g. when drug has low passive permeability). An on-going debate has focused on the issue of the interplay between CYP3A and P-gp such that high affinity to P-gp increases the exposure of drug to CYP3A through repeated cycling via passive diffusion and active efflux, decreasing the fraction of drug that escapes first pass gut metabolism (F(G)). The presence of P-gp in the gut wall and the high affinity of some CYP3A substrates to this <span class="hlt">transporter</span> are postulated to reduce the potential for saturating the enzymes, thus increasing gut wall first-pass metabolism for compounds which otherwise would have saturated CYP3A. Such inferences are based on assumptions in the modelling of oral drug <span class="hlt">absorption</span>. These models should be as mechanistic as possible and tractable using available in vitro and in vivo information. We review, through simulation, this subject and examine the interplay between gut wall metabolism and efflux <span class="hlt">transporters</span> by studying the fraction of dose absorbed into enterocytes (F(a)) and F(G) via</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li class="active"><span>22</span></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_22 --> <div id="page_23" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li class="active"><span>23</span></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="441"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25324188','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25324188"><span id="translatedtitle"><span class="hlt">Electron</span>-acceptor-dependent light <span class="hlt">absorption</span>, excited-state relaxation, and charge generation in triphenylamine dye-sensitized solar cells.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Li, Renzhi; Zhang, Min; Yan, Cancan; Yao, Zhaoyang; Zhang, Jing; Wang, Peng</p> <p>2015-01-01</p> <p>By choosing a simple triphenylamine <span class="hlt">electron</span> donor, we herein compare the influence of <span class="hlt">electron</span> acceptors benzothiadiazole benzoic acid (BTBA) and cyanoacrylic acid (CA), on energy levels, light <span class="hlt">absorption</span>, and dynamics of excited-state evolution and <span class="hlt">electron</span> injection. DFT and time-dependent DFT calculations disclosed remarkable intramolecular conformational changes for the excited states of these two donor-acceptor dyes. Photoinduced dihedral angle variation occurs to the triphenylamine unit in the CA dye and backbone planarization happens to conjugated aromatic blocks in the BTBA dye. Femtosecond spectroscopic measurements suggested the crucial role of having a long excited-state lifetime in maintaining a high <span class="hlt">electron</span>-injection yield because a reduced driving force for a low energy-gap dye can result in slower <span class="hlt">electron</span>-injection dynamics.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009OptMa..31.1256Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009OptMa..31.1256Z"><span id="translatedtitle">OH - <span class="hlt">absorption</span> in off-congruent LiNbO 3 crystals prepared by Li-poor vapor <span class="hlt">transport</span> equilibration</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhang, De-Long; Hua, Ping-Rang; Pun, Edwin Yue-Bun</p> <p>2009-06-01</p> <p>An X-cut and a Z-cut Li-deficient, non-congruent LiNbO 3 crystal were prepared by carrying out Li-poor vapor <span class="hlt">transport</span> equilibration (VTE) treatment on one mm thick congruent plates at 1100 °C for 170 h. From the measured optical <span class="hlt">absorption</span> edges (OAE), the Li 2O content is evaluated to be 47.74 ± 0.13 mol% in the X-cut plate and 47.61 ± 0.13 mol% in the Z-cut VTE crystal. The composition homogeneity is verified by measuring the OAE as a function of the crystal thickness. The visible optical <span class="hlt">absorption</span> and powder X-ray diffraction studies allow to conclude that both VTE crystals retain still the LiNbO 3 phase. OH - <span class="hlt">absorption</span> characteristics of the two VTE crystals were investigated in comparison with those of the as-grown crystals. The results show that the Li-poor VTE treatment only slightly modifies the area, spectral width, spectral shape and background <span class="hlt">absorption</span> of the OH - band. Comparison shows that the Li-poor VTE effects on the OH - <span class="hlt">absorption</span> have large differences from the Li-rich VTE effects in bandwidth and areas of three component peaks at 3466, 3481 and 3488 cm -1. These spectral differences are explained on the basis of the H + site occupation and crystal defect models taking into account the VTE effect on crystal defect concentration. The Li-poor VTE effects are attributed to the VTE inducing the redistribution of OH - ions in different sites.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/24977849','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/24977849"><span id="translatedtitle">Spatial <span class="hlt">transport</span> of atomic coherence in electromagnetically induced <span class="hlt">absorption</span> with a paraffin-coated Rb vapor cell.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Lee, Yoon-Seok; Moon, Han Seb</p> <p>2014-06-30</p> <p>We report the spatial <span class="hlt">transport</span> of spontaneously transferred atomic coherence (STAC) in electromagnetically induced <span class="hlt">absorption</span> (EIA), which resulted from moving atoms with the STAC of the 5S(1/2) (F = 2)-5P(3/2) (F' = 3) transition of (87)Rb in a paraffin-coated vapor cell. In our experiment, two channels were spatially separate; the writing channel (WC) generated STAC in the EIA configuration, and the reading channel (RC) retrieved the optical field from the spatially <span class="hlt">transported</span> STAC. <span class="hlt">Transported</span> between the spatially separated positions, the fast light pulse of EIA in the WC and the delayed light pulse in the RC were observed. When the laser direction of the RC was counter-propagated in the direction of the WC, we observed direction reversal of the <span class="hlt">transported</span> light pulse in the EIA medium. Furthermore, the delay time, the magnitude, and the width of the spatially <span class="hlt">transported</span> light pulse were investigated with respect to the distance between the two channels. PMID:24977849</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24977849','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24977849"><span id="translatedtitle">Spatial <span class="hlt">transport</span> of atomic coherence in electromagnetically induced <span class="hlt">absorption</span> with a paraffin-coated Rb vapor cell.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Lee, Yoon-Seok; Moon, Han Seb</p> <p>2014-06-30</p> <p>We report the spatial <span class="hlt">transport</span> of spontaneously transferred atomic coherence (STAC) in electromagnetically induced <span class="hlt">absorption</span> (EIA), which resulted from moving atoms with the STAC of the 5S(1/2) (F = 2)-5P(3/2) (F' = 3) transition of (87)Rb in a paraffin-coated vapor cell. In our experiment, two channels were spatially separate; the writing channel (WC) generated STAC in the EIA configuration, and the reading channel (RC) retrieved the optical field from the spatially <span class="hlt">transported</span> STAC. <span class="hlt">Transported</span> between the spatially separated positions, the fast light pulse of EIA in the WC and the delayed light pulse in the RC were observed. When the laser direction of the RC was counter-propagated in the direction of the WC, we observed direction reversal of the <span class="hlt">transported</span> light pulse in the EIA medium. Furthermore, the delay time, the magnitude, and the width of the spatially <span class="hlt">transported</span> light pulse were investigated with respect to the distance between the two channels.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://eric.ed.gov/?q=adobe&pg=3&id=EJ1068668','ERIC'); return false;" href="http://eric.ed.gov/?q=adobe&pg=3&id=EJ1068668"><span id="translatedtitle">Using Adobe Flash Animations of <span class="hlt">Electron</span> <span class="hlt">Transport</span> Chain to Teach and Learn Biochemistry</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Teplá, Milada; Klímová, Helena</p> <p>2015-01-01</p> <p>Teaching the subject of the <span class="hlt">electron</span> <span class="hlt">transport</span> chain is one of the most challenging aspects of the chemistry curriculum at the high school level. This article presents an educational program called "<span class="hlt">Electron</span> <span class="hlt">Transport</span> Chain" which consists of 14 visual animations including a biochemistry quiz. The program was created in the Adobe Flash…</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1187991','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1187991"><span id="translatedtitle">Towards simultaneous measurements of <span class="hlt">electronic</span> and structural properties in ultra-fast x-ray free <span class="hlt">electron</span> laser <span class="hlt">absorption</span> spectroscopy experiments</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Gaudin, J.; Fourment, C.; Cho, B. I.; Engelhorn, K.; Galtier, E.; Harmand, M.; Leguay, P. M.; Lee, H. J.; Nagler, B.; Nakatsutsumi, M.; Ozkan, C.; Störmer, M.; Toleikis, S.; Tschentscher, Th.; Heimann, P. A.; Dorchies, F.</p> <p>2014-04-17</p> <p>The rapidly growing ultrafast science with X-ray lasers unveils atomic scale processes with unprecedented time resolution bringing the so called “molecular movie” within reach. X-ray <span class="hlt">absorption</span> spectroscopy is one of the most powerful x-ray techniques providing both local atomic order and <span class="hlt">electronic</span> structure when coupled with ad-hoc theory. Collecting <span class="hlt">absorption</span> spectra within few x-ray pulses is possible only in a dispersive setup. We demonstrate ultrafast time-resolved measurements of the LIII-edge x-ray <span class="hlt">absorption</span> near-edge spectra of irreversibly laser excited Molybdenum using an average of only few x-ray pulses with a signal to noise ratio limited only by the saturation level of the detector. The simplicity of the experimental set-up makes this technique versatile and applicable for a wide range of pump-probe experiments, particularly in the case of non-reversible processes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/pages/biblio/1187991-towards-simultaneous-measurements-electronic-structural-properties-ultra-fast-ray-free-electron-laser-absorption-spectroscopy-experiments','SCIGOV-DOEP'); return false;" href="http://www.osti.gov/pages/biblio/1187991-towards-simultaneous-measurements-electronic-structural-properties-ultra-fast-ray-free-electron-laser-absorption-spectroscopy-experiments"><span id="translatedtitle">Towards simultaneous measurements of <span class="hlt">electronic</span> and structural properties in ultra-fast x-ray free <span class="hlt">electron</span> laser <span class="hlt">absorption</span> spectroscopy experiments</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Gaudin, J.; Fourment, C.; Cho, B. I.; Engelhorn, K.; Galtier, E.; Harmand, M.; Leguay, P. M.; Lee, H. J.; Nagler, B.; Nakatsutsumi, M.; et al</p> <p>2014-04-17</p> <p>The rapidly growing ultrafast science with X-ray lasers unveils atomic scale processes with unprecedented time resolution bringing the so called “molecular movie” within reach. X-ray <span class="hlt">absorption</span> spectroscopy is one of the most powerful x-ray techniques providing both local atomic order and <span class="hlt">electronic</span> structure when coupled with ad-hoc theory. Collecting <span class="hlt">absorption</span> spectra within few x-ray pulses is possible only in a dispersive setup. We demonstrate ultrafast time-resolved measurements of the LIII-edge x-ray <span class="hlt">absorption</span> near-edge spectra of irreversibly laser excited Molybdenum using an average of only few x-ray pulses with a signal to noise ratio limited only by the saturation level ofmore » the detector. The simplicity of the experimental set-up makes this technique versatile and applicable for a wide range of pump-probe experiments, particularly in the case of non-reversible processes.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014NatSR...4E4724G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014NatSR...4E4724G"><span id="translatedtitle">Towards simultaneous measurements of <span class="hlt">electronic</span> and structural properties in ultra-fast x-ray free <span class="hlt">electron</span> laser <span class="hlt">absorption</span> spectroscopy experiments</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gaudin, J.; Fourment, C.; Cho, B. I.; Engelhorn, K.; Galtier, E.; Harmand, M.; Leguay, P. M.; Lee, H. J.; Nagler, B.; Nakatsutsumi, M.; Ozkan, C.; Störmer, M.; Toleikis, S.; Tschentscher, Th; Heimann, P. A.; Dorchies, F.</p> <p>2014-04-01</p> <p>The rapidly growing ultrafast science with X-ray lasers unveils atomic scale processes with unprecedented time resolution bringing the so called ``molecular movie'' within reach. X-ray <span class="hlt">absorption</span> spectroscopy is one of the most powerful x-ray techniques providing both local atomic order and <span class="hlt">electronic</span> structure when coupled with ad-hoc theory. Collecting <span class="hlt">absorption</span> spectra within few x-ray pulses is possible only in a dispersive setup. We demonstrate ultrafast time-resolved measurements of the LIII-edge x-ray <span class="hlt">absorption</span> near-edge spectra of irreversibly laser excited Molybdenum using an average of only few x-ray pulses with a signal to noise ratio limited only by the saturation level of the detector. The simplicity of the experimental set-up makes this technique versatile and applicable for a wide range of pump-probe experiments, particularly in the case of non-reversible processes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24740172','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24740172"><span id="translatedtitle">Towards simultaneous measurements of <span class="hlt">electronic</span> and structural properties in ultra-fast x-ray free <span class="hlt">electron</span> laser <span class="hlt">absorption</span> spectroscopy experiments.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Gaudin, J; Fourment, C; Cho, B I; Engelhorn, K; Galtier, E; Harmand, M; Leguay, P M; Lee, H J; Nagler, B; Nakatsutsumi, M; Ozkan, C; Störmer, M; Toleikis, S; Tschentscher, Th; Heimann, P A; Dorchies, F</p> <p>2014-04-17</p> <p>The rapidly growing ultrafast science with X-ray lasers unveils atomic scale processes with unprecedented time resolution bringing the so called "molecular movie" within reach. X-ray <span class="hlt">absorption</span> spectroscopy is one of the most powerful x-ray techniques providing both local atomic order and <span class="hlt">electronic</span> structure when coupled with ad-hoc theory. Collecting <span class="hlt">absorption</span> spectra within few x-ray pulses is possible only in a dispersive setup. We demonstrate ultrafast time-resolved measurements of the LIII-edge x-ray <span class="hlt">absorption</span> near-edge spectra of irreversibly laser excited Molybdenum using an average of only few x-ray pulses with a signal to noise ratio limited only by the saturation level of the detector. The simplicity of the experimental set-up makes this technique versatile and applicable for a wide range of pump-probe experiments, particularly in the case of non-reversible processes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015PhDT........43H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015PhDT........43H"><span id="translatedtitle">An <span class="hlt">Electronic</span> Structure Approach to Charge Transfer and <span class="hlt">Transport</span> in Molecular Building Blocks for Organic Optoelectronics</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hendrickson, Heidi Phillips</p> <p></p> <p>A fundamental understanding of charge separation in organic materials is necessary for the rational design of optoelectronic devices suited for renewable energy applications and requires a combination of theoretical, computational, and experimental methods. Density functional theory (DFT) and time-dependent (TD)DFT are cost effective ab-initio approaches for calculating fundamental properties of large molecular systems, however conventional DFT methods have been known to fail in accurately characterizing frontier orbital gaps and charge transfer states in molecular systems. In this dissertation, these shortcomings are addressed by implementing an optimally-tuned range-separated hybrid (OT-RSH) functional approach within DFT and TDDFT. The first part of this thesis presents the way in which RSH-DFT addresses the shortcomings in conventional DFT. Environmentally-corrected RSH-DFT frontier orbital energies are shown to correspond to thin film measurements for a set of organic semiconducting molecules. Likewise, the improved RSH-TDDFT description of charge transfer excitations is benchmarked using a model ethene dimer and silsesquioxane molecules. In the second part of this thesis, RSH-DFT is applied to chromophore-functionalized silsesquioxanes, which are currently investigated as candidates for building blocks in optoelectronic applications. RSH-DFT provides insight into the nature of <span class="hlt">absorptive</span> and emissive states in silsesquioxanes. While <span class="hlt">absorption</span> primarily involves transitions localized on one chromophore, charge transfer between chromophores and between chromophore and silsesquioxane cage have been identified. The RSH-DFT approach, including a protocol accounting for complex environmental effects on charge transfer energies, was tested and validated against experimental measurements. The third part of this thesis addresses quantum <span class="hlt">transport</span> through nano-scale junctions. The ability to quantify a molecular junction via spectroscopic methods is crucial to their</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25798659','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25798659"><span id="translatedtitle">Analysis and calculation of <span class="hlt">electronic</span> properties and light <span class="hlt">absorption</span> of defective sulfur-doped silicon and theoretical photoelectric conversion efficiency.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Jiang, He; Chen, Changshui</p> <p>2015-04-23</p> <p>Most material properties can be traced to <span class="hlt">electronic</span> structures. Black silicon produced from SF6 or sulfur powder via irradiation with femtosecond laser pulses displays decreased infrared <span class="hlt">absorption</span> after annealing, with almost no corresponding change in visible light <span class="hlt">absorption</span>. The high-intensity laser pulses destroy the original crystal structure, and the doping element changes the material performance. In this work, the structural and <span class="hlt">electronic</span> properties of several sulfur-doped silicon systems are investigated using first principle calculations. Depending on the sulfur concentration (level of doping) and the behavior of the sulfur atoms in the silicon lattice, different states or an absence of states are exhibited, compared with the undoped system. Moreover, the visible-infrared light <span class="hlt">absorption</span> intensities are structure specific. The results of our theoretical calculations show that the conversion efficiency of sulfur-doped silicon solar cells depends on the sulfur concentrations. Additionally, two types of defect configurations exhibit light <span class="hlt">absorption</span> characteristics that differ from the other configurations. These two structures produce a rapid increase in the theoretical photoelectric conversion efficiency in the range of the specific chemical potential studied. By controlling the positions of the atomic sulfur and the sulfur concentration in the preparation process, an efficient photovoltaic (PV) material may be obtainable.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/25798659','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/25798659"><span id="translatedtitle">Analysis and calculation of <span class="hlt">electronic</span> properties and light <span class="hlt">absorption</span> of defective sulfur-doped silicon and theoretical photoelectric conversion efficiency.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Jiang, He; Chen, Changshui</p> <p>2015-04-23</p> <p>Most material properties can be traced to <span class="hlt">electronic</span> structures. Black silicon produced from SF6 or sulfur powder via irradiation with femtosecond laser pulses displays decreased infrared <span class="hlt">absorption</span> after annealing, with almost no corresponding change in visible light <span class="hlt">absorption</span>. The high-intensity laser pulses destroy the original crystal structure, and the doping element changes the material performance. In this work, the structural and <span class="hlt">electronic</span> properties of several sulfur-doped silicon systems are investigated using first principle calculations. Depending on the sulfur concentration (level of doping) and the behavior of the sulfur atoms in the silicon lattice, different states or an absence of states are exhibited, compared with the undoped system. Moreover, the visible-infrared light <span class="hlt">absorption</span> intensities are structure specific. The results of our theoretical calculations show that the conversion efficiency of sulfur-doped silicon solar cells depends on the sulfur concentrations. Additionally, two types of defect configurations exhibit light <span class="hlt">absorption</span> characteristics that differ from the other configurations. These two structures produce a rapid increase in the theoretical photoelectric conversion efficiency in the range of the specific chemical potential studied. By controlling the positions of the atomic sulfur and the sulfur concentration in the preparation process, an efficient photovoltaic (PV) material may be obtainable. PMID:25798659</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2010-title41-vol3/pdf/CFR-2010-title41-vol3-sec102-118-65.pdf','CFR'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2010-title41-vol3/pdf/CFR-2010-title41-vol3-sec102-118-65.pdf"><span id="translatedtitle">41 CFR 102-118.65 - Can my agency receive <span class="hlt">electronic</span> billing for payment of <span class="hlt">transportation</span> services?</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2010&page.go=Go">Code of Federal Regulations, 2010 CFR</a></p> <p></p> <p>2010-07-01</p> <p>... <span class="hlt">electronic</span> billing for payment of <span class="hlt">transportation</span> services? 102-118.65 Section 102-118.65 Public Contracts and... <span class="hlt">Transportation</span> Services § 102-118.65 Can my agency receive <span class="hlt">electronic</span> billing for payment of <span class="hlt">transportation</span>... to use <span class="hlt">electronic</span> billing for the procurement and billing of <span class="hlt">transportation</span> services....</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/411733','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/411733"><span id="translatedtitle">Multigroup Boltzmann-Fokker-Planck <span class="hlt">electron</span>-photon <span class="hlt">transport</span> capability in MCNP</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Adams, K.J.; Hart, M.</p> <p>1995-12-31</p> <p>The MCNP code system has a robust multigroup <span class="hlt">transport</span> capability that includes a Boltzmann-Fokker-Planck (MGBFP) <span class="hlt">transport</span> algorithm to perform coupled <span class="hlt">electron</span>-photon or other coupled charged and neutral particle <span class="hlt">transport</span> in either a forward or adjoint mode. This paper discusses this capability.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/1025494','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/1025494"><span id="translatedtitle">Correlated single-crystal <span class="hlt">electronic</span> <span class="hlt">absorption</span> spectroscopy and X-ray crystallography at NSLS beamline X26-C</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Orville, A.M.; Buono, R.; Cowan, M.; Heroux, A.; Shea-McCarthy, G.; Schneider, D. K.; Skinner, J. M.; Skinner, M. J.; Stoner-Ma, D.; Sweet, R. M.</p> <p>2011-05-01</p> <p>The research philosophy and new capabilities installed at NSLS beamline X26-C to support <span class="hlt">electronic</span> <span class="hlt">absorption</span> and Raman spectroscopies coupled with X-ray diffraction are reviewed. This beamline is dedicated full time to multidisciplinary studies with goals that include revealing the relationship between the <span class="hlt">electronic</span> and atomic structures in macromolecules. The beamline instrumentation has been fully integrated such that optical <span class="hlt">absorption</span> spectra and X-ray diffraction images are interlaced. Therefore, optical changes induced by X-ray exposure can be correlated with X-ray diffraction data collection. The installation of Raman spectroscopy into the beamline is also briefly reviewed. Data are now routinely generated almost simultaneously from three complementary types of experiments from the same sample. The beamline is available now to the NSLS general user population.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/1041896','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/1041896"><span id="translatedtitle">Correlated Single-Crystal <span class="hlt">Electronic</span> <span class="hlt">Absorption</span> Spectroscopy and X-ray Crystallography at NSLS Beamline X26-C</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>A Orville; R Buono; M Cowan; A Heroux; G Shea-McCarthy; D Schneider; J Skinner; M Skinner; D Stoner-Ma; R Sweet</p> <p>2011-12-31</p> <p>The research philosophy and new capabilities installed at NSLS beamline X26-C to support <span class="hlt">electronic</span> <span class="hlt">absorption</span> and Raman spectroscopies coupled with X-ray diffraction are reviewed. This beamline is dedicated full time to multidisciplinary studies with goals that include revealing the relationship between the <span class="hlt">electronic</span> and atomic structures in macromolecules. The beamline instrumentation has been fully integrated such that optical <span class="hlt">absorption</span> spectra and X-ray diffraction images are interlaced. Therefore, optical changes induced by X-ray exposure can be correlated with X-ray diffraction data collection. The installation of Raman spectroscopy into the beamline is also briefly reviewed. Data are now routinely generated almost simultaneously from three complementary types of experiments from the same sample. The beamline is available now to the NSLS general user population.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/22314387','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22314387"><span id="translatedtitle">Local versus global <span class="hlt">electronic</span> properties of chalcopyrite alloys: X-ray <span class="hlt">absorption</span> spectroscopy and ab initio calculations</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Sarmiento-Pérez, Rafael; Botti, Silvana; Schnohr, Claudia S.; Lauermann, Iver; Rubio, Angel; Johnson, Benjamin</p> <p>2014-09-07</p> <p>Element-specific unoccupied <span class="hlt">electronic</span> states of Cu(In, Ga)S{sub 2} were studied as a function of the In/Ga ratio by combining X-ray <span class="hlt">absorption</span> spectroscopy with density functional theory calculations. The S <span class="hlt">absorption</span> edge shifts with changing In/Ga ratio as expected from the variation of the band gap. In contrast, the cation edge positions are largely independent of composition despite the changing band gap. This unexpected behavior is well reproduced by our calculations and originates from the dependence of the <span class="hlt">electronic</span> states on the local atomic environment. The changing band gap arises from a changing spatial average of these localized states with changing alloy composition.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2014NJPh...16g3014T&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2014NJPh...16g3014T&link_type=ABSTRACT"><span id="translatedtitle">A reduced model for relativistic <span class="hlt">electron</span> beam <span class="hlt">transport</span> in solids and dense plasmas</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Touati, M.; Feugeas, J.-L.; Nicolaï, Ph; Santos, J. J.; Gremillet, L.; Tikhonchuk, V. T.</p> <p>2014-07-01</p> <p>A hybrid reduced model for relativistic <span class="hlt">electron</span> beam <span class="hlt">transport</span> based on the angular moments of the relativistic kinetic equation with a special closure is presented. It takes into account collective effects with the self-generated electromagnetic fields as well as collisional effects with the slowing down of the relativistic <span class="hlt">electrons</span> by plasmons, bound and free <span class="hlt">electrons</span> and their angular scattering on both ions and <span class="hlt">electrons</span>. This model allows for fast computations of relativistic <span class="hlt">electron</span> beam <span class="hlt">transport</span> while describing their energy distribution evolution. Despite the loss of information concerning the angular distribution of the <span class="hlt">electron</span> beam, the model reproduces analytical estimates in the academic case of a monodirectional and monoenergetic <span class="hlt">electron</span> beam propagating through a warm and dense plasma and hybrid particle-in-cell simulation results in a realistic laser-generated <span class="hlt">electron</span> beam <span class="hlt">transport</span> case.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3572443','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3572443"><span id="translatedtitle">Hot <span class="hlt">electron</span> <span class="hlt">transport</span> in a strongly correlated transition-metal oxide</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Rana, Kumari Gaurav; Yajima, Takeaki; Parui, Subir; Kemper, Alexander F.; Devereaux, Thomas P.; Hikita, Yasuyuki; Hwang, Harold Y.; Banerjee, Tamalika</p> <p>2013-01-01</p> <p>Oxide heterointerfaces are ideal for investigating strong correlation effects to <span class="hlt">electron</span> <span class="hlt">transport</span>, relevant for oxide-<span class="hlt">electronics</span>. Using hot-<span class="hlt">electrons</span>, we probe <span class="hlt">electron</span> <span class="hlt">transport</span> perpendicular to the La0.7Sr0.3MnO3 (LSMO)- Nb-doped SrTiO3 (Nb:STO) interface and find the characteristic hot-<span class="hlt">electron</span> attenuation length in LSMO to be 1.48 ± 0.10 unit cells (u.c.) at −1.9 V, increasing to 2.02 ± 0.16 u.c. at −1.3 V at room temperature. Theoretical analysis of this energy dispersion reveals the dominance of <span class="hlt">electron-electron</span> and polaron scattering. Direct visualization of the local <span class="hlt">electron</span> <span class="hlt">transport</span> shows different transmission at the terraces and at the step-edges. PMID:23429420</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015Nanos...7.1736L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015Nanos...7.1736L"><span id="translatedtitle">Dependency of magnetic microwave <span class="hlt">absorption</span> on surface architecture of Co20Ni80 hierarchical structures studied by <span class="hlt">electron</span> holography</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Liu, Qinhe; Xu, Xianhui; Xia, Weixing; Che, Renchao; Chen, Chen; Cao, Qi; He, Jingang</p> <p>2015-01-01</p> <p>To design and fabricate rational surface architecture of individual particles is one of the key factors that affect their magnetic properties and microwave <span class="hlt">absorption</span> capability, which is still a great challenge. Herein, a series of Co20Ni80 hierarchical structures with different surface morphologies, including flower-, urchin-, ball-, and chain-like morphologies, were obtained using structure-directing templates via a facile one-step solvothermal treatment. The microwave reflection loss (RL) of urchin-like Co20Ni80 hierarchical structures reaches as high as -33.5 dB at 3 GHz, with almost twice the RL intensity of the ball- and chain-like structures, and the <span class="hlt">absorption</span> bandwidth (<-10 dB) is about 5.5 GHz for the flower-like morphology, indicating that the surface nanospikes and nanoflakes on the Co20Ni80 microsphere surfaces have great influences on their magnetic microwave <span class="hlt">absorption</span> properties. <span class="hlt">Electron</span> holography analysis reveals that the surface nanospikes and nanoflakes could generate a high density of stray magnetic flux lines and contribute a large saturation magnetization (105.62 emu g-1 for urchin-like and 96.41 emu g-1 for flower-like morphology), leading the urchin-like and flower-like Co20Ni80 to possess stronger microwave RL compared with the ball-like and chain-like Co20Ni80 alloys. The eddy-current <span class="hlt">absorption</span> mechanism μ''(μ')-2(f)-1 is dominant in the frequency region above 8 GHz, implying that eddy-current loss is a vital factor for microwave RL in the high frequency range. It can be supposed from our findings that different surface morphologies of magnetic hierarchical structures might become an effective path to achieve high-performance microwave <span class="hlt">absorption</span> for electromagnetic shielding and stealth camouflage applications.To design and fabricate rational surface architecture of individual particles is one of the key factors that affect their magnetic properties and microwave <span class="hlt">absorption</span> capability, which is still a great challenge. Herein, a</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li class="active"><span>23</span></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_23 --> <div id="page_24" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li class="active"><span>24</span></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="461"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1096262','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1096262"><span id="translatedtitle">Modeling <span class="hlt">electron</span> <span class="hlt">transport</span> in the presence of electric and magnetic fields.</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Fan, Wesley C.; Drumm, Clifton Russell; Pautz, Shawn D.; Turner, C. David</p> <p>2013-09-01</p> <p>This report describes the theoretical background on modeling <span class="hlt">electron</span> <span class="hlt">transport</span> in the presence of electric and magnetic fields by incorporating the effects of the Lorentz force on <span class="hlt">electron</span> motion into the Boltzmann <span class="hlt">transport</span> equation. Electromagnetic fields alter the <span class="hlt">electron</span> energy and trajectory continuously, and these effects can be characterized mathematically by differential operators in terms of <span class="hlt">electron</span> energy and direction. Numerical solution techniques, based on the discrete-ordinates and finite-element methods, are developed and implemented in an existing radiation <span class="hlt">transport</span> code, SCEPTRE.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25615475','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25615475"><span id="translatedtitle">Saturable <span class="hlt">absorption</span> of an x-ray free-<span class="hlt">electron</span>-laser heated solid-density aluminum plasma.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Rackstraw, D S; Ciricosta, O; Vinko, S M; Barbrel, B; Burian, T; Chalupský, J; Cho, B I; Chung, H-K; Dakovski, G L; Engelhorn, K; Hájková, V; Heimann, P; Holmes, M; Juha, L; Krzywinski, J; Lee, R W; Toleikis, S; Turner, J J; Zastrau, U; Wark, J S</p> <p>2015-01-01</p> <p>High-intensity x-ray pulses from an x-ray free-<span class="hlt">electron</span> laser are used to heat and probe a solid-density aluminum sample. The photon-energy-dependent transmission of the heating beam is studied through the use of a photodiode. Saturable <span class="hlt">absorption</span> is observed, with the resulting transmission differing significantly from the cold case, in good agreement with atomic-kinetics simulations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2003NIMPA.507..572S&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2003NIMPA.507..572S&link_type=ABSTRACT"><span id="translatedtitle">Energy <span class="hlt">absorption</span> of free rare gas clusters irradiated by intense VUV pulses of a free <span class="hlt">electron</span> laser</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Schulz, J.; Wabnitz, H.; Laarmann, T.; Gürtler, P.; Laasch, W.; Swiderski, A.; Möller, Th.; de Castro, A. R. B.</p> <p>2003-07-01</p> <p>As one of the first experiments at the free <span class="hlt">electron</span> laser of the TESLA Test Facility (TTF) the Coulomb explosion of Xenon clusters irradiated with high intensity pulses at a wavelength of 98 nm has been observed. Classical trajectory calculations have been performed in order to illuminate the energy <span class="hlt">absorption</span> process. Comparison with typical parameters in the infrared regime shows that above barrier ionization is suppressed due to the fast oscillating field and thermionic ionization prevails.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25477003','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25477003"><span id="translatedtitle">Membrane <span class="hlt">transport</span> of nobilin conjugation products and use of the extract of Chamomillae romanae flos influence <span class="hlt">absorption</span> of nobilin in the Caco-2 model.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Thormann, U; Hänggi, R; Kreuter, M; Imanidis, G</p> <p>2015-04-01</p> <p>The purpose of this work was to investigate the role of bioconjugation and carrier mediated efflux of conjugation products in the <span class="hlt">absorption</span> mechanism of the sesquiterpene lactone nobilin in the Caco-2 model in vitro and to elucidate the impact of the extract of Chamomillae romanae flos and its ingredients on <span class="hlt">absorption</span>. <span class="hlt">Transport</span> experiments with inhibitors of P-gp, BCRP, and MRPs were performed to detect efflux and its connection to bioconversion and the effect of different ingredients of the plant extract on <span class="hlt">absorption</span> processes was determined. Permeability, <span class="hlt">transport</span> and bioconversion parameter values were deduced by kinetic multi-compartment modeling. Nobilin exhibited high permeability, low relative <span class="hlt">absorption</span> and fast bioconversion producing glucuronide, cysteine conjugate, and glutathione conjugate that were <span class="hlt">transported</span> by P-gp (the first two), apical MRP2 and basal MRP3 and possibly MRP1 out of the cell. Inhibition of efflux resulted in diminished bioconjugation and improved <span class="hlt">absorption</span>. The extract increased the relative fraction absorbed primarily by directly inhibiting bioconversion, and by reducing efflux. Individual extract ingredients could only partly explain this effect. Extensive bioconversion, hence, limited <span class="hlt">absorption</span> of nobilin in the Caco-2 model and the interplay between conjugation and efflux was shown to provide a possible mechanism for <span class="hlt">absorption</span> increase. Plant extract increased <span class="hlt">absorption</span> by this mechanism in addition to metabolic enzyme inhibition.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/459863','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/459863"><span id="translatedtitle">A simplified spherical harmonic method for coupled <span class="hlt">electron</span>-photon <span class="hlt">transport</span> calculations</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Josef, J.A.</p> <p>1996-12-01</p> <p>In this thesis we have developed a simplified spherical harmonic method (SP{sub N} method) and associated efficient solution techniques for 2-D multigroup <span class="hlt">electron</span>-photon <span class="hlt">transport</span> calculations. The SP{sub N} method has never before been applied to charged-particle <span class="hlt">transport</span>. We have performed a first time Fourier analysis of the source iteration scheme and the P{sub 1} diffusion synthetic acceleration (DSA) scheme applied to the 2-D SP{sub N} equations. Our theoretical analyses indicate that the source iteration and P{sub 1} DSA schemes are as effective for the 2-D SP{sub N} equations as for the 1-D S{sub N} equations. Previous analyses have indicated that the P{sub 1} DSA scheme is unstable (with sufficiently forward-peaked scattering and sufficiently small <span class="hlt">absorption</span>) for the 2-D S{sub N} equations, yet is very effective for the 1-D S{sub N} equations. In addition, we have applied an angular multigrid acceleration scheme, and computationally demonstrated that it performs as well for the 2-D SP{sub N} equations as for the 1-D S{sub N} equations. It has previously been shown for 1-D S{sub N} calculations that this scheme is much more effective than the DSA scheme when scattering is highly forward-peaked. We have investigated the applicability of the SP{sub N} approximation to two different physical classes of problems: satellite <span class="hlt">electronics</span> shielding from geomagnetically trapped <span class="hlt">electrons</span>, and <span class="hlt">electron</span> beam problems. In the space shielding study, the SP{sub N} method produced solutions that are accurate within 10% of the benchmark Monte Carlo solutions, and often orders of magnitude faster than Monte Carlo. We have successfully modeled quasi-void problems and have obtained excellent agreement with Monte Carlo. We have observed that the SP{sub N} method appears to be too diffusive an approximation for beam problems. This result, however, is in agreement with theoretical expectations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/23698325','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/23698325"><span id="translatedtitle">Stepping stones in the <span class="hlt">electron</span> <span class="hlt">transport</span> from cells to electrodes in Geobacter sulfurreducens biofilms.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Bonanni, Pablo Sebastián; Massazza, Diego; Busalmen, Juan Pablo</p> <p>2013-07-01</p> <p>Geobacter sulfurreducens bacteria grow on biofilms and have the particular ability of using polarized electrodes as the final <span class="hlt">electron</span> acceptor of their respiratory chain. In these biofilms, <span class="hlt">electrons</span> are <span class="hlt">transported</span> through distances of more than 50 μm before reaching the electrode. The way in which <span class="hlt">electrons</span> are <span class="hlt">transported</span> across the biofilm matrix through such large distances remains under intense discussion. None of the two mechanisms proposed for explaining the process, <span class="hlt">electron</span> hopping through outer membrane cytochromes and metallic like conduction through conductive PilA filaments, can account for all the experimental evidence collected so far. Aiming at providing new elements for understanding the basis for <span class="hlt">electron</span> <span class="hlt">transport</span>, in this perspective article we present a modelled structure of Geobacter pilus. Its analysis in combination with already existing experimental evidence gives support to the proposal of the "stepping stone" mechanism, in which the combined action of pili and cytochromes allows long range <span class="hlt">electron</span> <span class="hlt">transport</span> through the biofilm. PMID:23698325</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5557574','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5557574"><span id="translatedtitle">Subnanosecond time-resolved optical <span class="hlt">absorption</span> studies of <span class="hlt">electron</span> solvation in ice. [25-ps pulse of 20-MeV <span class="hlt">electrons</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Warman, J.M.; Kunst, M.; Jonah, C.D.</p> <p>1983-10-13</p> <p>Optical <span class="hlt">absorption</span> studies of pulse-irradiated ice have been carried out with subnanosecond time resolution. A growth in the solvated <span class="hlt">electron</span> <span class="hlt">absorption</span> is observed with a risetime of 450 ps at -5/sup 0/C. The activation energy for relaxation of the matrix following localization is 0.3 eV. Below -35/sup 0/C localization at trapping sites becomes the rate-controlling step in solvation. Addition of 10/sup -2/M NH/sub 4/F considerably increases the overall solvation time by reducing the initial rate of dry <span class="hlt">electron</span> localization at defects. A second absorbing species is produced immediately in the pulse with a yield Gepsilon/sub 660/ = 9 x 10 M/sup -3/ cm/sup -1/ (100 eV)/sup -1/, which is independent of temperature. This is tentatively ascribed to an exciton state. 4 figures, 1 table.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/18614339','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/18614339"><span id="translatedtitle">Region-dependent <span class="hlt">absorption</span> of faropenem shared with foscarnet, a phosphate <span class="hlt">transporter</span> substrate, in the rat small intestine.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Saitoh, Hiroshi; Sawazaki, Rinako; Oda, Masako; Kobayashi, Michiya</p> <p>2008-09-01</p> <p>Faropenem, a penem antibiotic, is orally active despite its hydrophilic nature. However, its intestinal <span class="hlt">absorption</span> has not yet been characterised in detail. This study was undertaken to determine the factors regulating faropenem <span class="hlt">absorption</span> using intestinal loops prepared in the rat duodenum, jejunum and terminal ileum. Faropenem disappearance was much greater than that of cefotaxime and meropenem, and faropenem disappeared more extensively from the terminal ileum than from the jejunum or duodenum. In contrast to faropenem, the disappearance of ceftibuten was much greater from the duodenum and jejunum than from the terminal ileum. As the accumulation and enzymatic degradation of faropenem was minimal in the intestinal mucosa, faropenem was considered to enter the portal vein smoothly after its disappearance from the intestinal loops. Faropenem disappearance was not significantly influenced by the presence of monocarboxylic acids, amino acids or bile acid. Dipeptides such as L-carnosine and glycylglycine slightly but significantly lowered faropenem disappearance from the terminal ileum. On the other hand, foscarnet exerted a marked inhibitory effect on faropenem disappearance, but the antiviral agent did not modulate ceftibuten <span class="hlt">absorption</span>. The present results suggest that faropenem is in part absorbed via a phosphate <span class="hlt">transporter</span> present in the rat small intestine. PMID:18614339</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2007AcSpA..66..849R&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2007AcSpA..66..849R&link_type=ABSTRACT"><span id="translatedtitle">pH-Induced changes in <span class="hlt">electronic</span> <span class="hlt">absorption</span> and fluorescence spectra of phenazine derivatives</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ryazanova, O. A.; Voloshin, I. M.; Makitruk, V. L.; Zozulya, V. N.; Karachevtsev, V. A.</p> <p>2007-04-01</p> <p>The visible <span class="hlt">electronic</span> <span class="hlt">absorption</span> and fluorescence spectra as well as fluorescence polarization degrees of imidazo-[4,5-d]-phenazine (F1), 2-methylimidazo-[4,5-d]-phenazine (F2), 2-trifluoridemethylimidazo-[4,5-d]-phenazine (F3), 1,2,3-triazole-[4,5-d]-phenazine (F4) and their glycosides, imidazo-[4,5-d]-phenazine-N1-β- D-ribofuranoside (F1rib), 1,2,3-triazole-[4,5-d]-phenazine-N1-β- D-glucopyranoside (F4gl), were investigated in aqueous buffered solutions over the pH range of 0-12, where the spectral transformations were found to be reversible. The effects of protonation and deprotonation on spectral properties of these dyes were studied. We have determined the ranges of pH, where individual ionic species are predominant. In aqueous buffered solutions the fluorescence was found only for neutral species of F1, F1rib, F2, and F4gl dyes, whereas for the ionic forms of these dyes, as well as for F3 and F4 ones, the fluorescence has not been detected. The concentrational deprotonation p Ka values were evaluated from experimental data. It was shown that donor-acceptor properties of the substituent group in the second position of the pentagonal ring substantially affect the values of the deprotonation constants and the character of protonation for chromophore. The substitution of a hydrogen atom in the NH-group by the sugar residue blocks the formation of the anionic species, and results in enhancement of the dye emission intensity. The steep emission dependence for F1 and F1rib over pH range of 0-7 with intensities ratio of IpH 7/ IpH 1 = 60 allows us to propose them as possible indicator dyes in luminescence based pH sensors for investigation of processes accompanied by acidification, e.g. as gastric pH-sensors. A comparative analysis of the studied dyes has shown that F4gl is the most promising compound to be used as a fluorescent probe for investigation of molecular hybridization of nucleic acids.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AcSpA.135.1066M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AcSpA.135.1066M"><span id="translatedtitle">DFT and TD-DFT study on geometries, <span class="hlt">electronic</span> structures and <span class="hlt">electronic</span> <span class="hlt">absorption</span> of some metal free dye sensitizers for dye sensitized solar cells</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mohr, T.; Aroulmoji, V.; Ravindran, R. Samson; Müller, M.; Ranjitha, S.; Rajarajan, G.; Anbarasan, P. M.</p> <p>2015-01-01</p> <p>The geometries, <span class="hlt">electronic</span> structures, polarizabilities and hyperpolarizabilities of 2-hydroxynaphthalene-1,4-dione (henna1), 3-(5-((1E)-2-(1,4-dihydro-1,4-dioxonaphthalen-3-yloxy) vinyl) thiophen-2-yl)-2-isocyanoacrylic acid (henna2) and anthocyanin dye sensitizers were studied based on density functional theory (DFT) using the hybrid functional B3LYP. The Ultraviolet-Visible (UV-Vis) spectrum was investigated by using a hybrid method which combines the properties and dynamics of many-body in the presence of time-dependent (TD) potentials, i.e. TDSCF-DFT (B3LYP). Features of the <span class="hlt">electronic</span> <span class="hlt">absorption</span> spectrum in the visible and near-UV regions were plotted and assigned based on TD-DFT calculations. Due to the <span class="hlt">absorption</span>, bands of the metal-organic compound are n → π* present. The calculated results suggest that the three lowest energy excited states of the investigated dye sensitizers are due to photoinduced <span class="hlt">electron</span> transfer processes. The interfacial <span class="hlt">electron</span> transfer between semiconductor TiO2 electrode and dye sensitizer is owing to an <span class="hlt">electron</span> injection process from excited dye to the semiconductor's conduction band. The role of linking the henna1 dye with a carboxylic acid via a thiophene bridge was analyzed. The results are that using a stronger π-conjugate bridge as well as a strong donator and acceptor group enhances the efficiency.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/7252688','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/7252688"><span id="translatedtitle">Nonlocal <span class="hlt">electron</span> <span class="hlt">transport</span> in the presence of high-intensity laser irradiation</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Epperlein, E.M.; Short, R.W. )</p> <p>1994-08-01</p> <p>We investigate <span class="hlt">electron</span> <span class="hlt">transport</span> in a plasma heated by spatially modulated laser irradiation. When the heating rate is greater than the <span class="hlt">electron-electron</span> collision rate, the thermal conductivity is reduced by a factor of 3 to 4 from the Spitzer-Haerm [Phys. Rev. 89, 977 (1953)] value for [ital K][lambda][sub [ital e</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27420809','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27420809"><span id="translatedtitle">Competition of static magnetic and dynamic photon forces in <span class="hlt">electronic</span> <span class="hlt">transport</span> through a quantum dot.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Rauf Abdullah, Nzar; Tang, Chi-Shung; Manolescu, Andrei; Gudmundsson, Vidar</p> <p>2016-09-21</p> <p>We investigate theoretically the balance of the static magnetic and the dynamical photon forces in the <span class="hlt">electron</span> <span class="hlt">transport</span> through a quantum dot in a photon cavity with a single photon mode. The quantum dot system is connected to external leads and the total system is exposed to a static perpendicular magnetic field. We explore the <span class="hlt">transport</span> characteristics through the system by tuning the ratio, [Formula: see text], between the photon energy, [Formula: see text], and the cyclotron energy, [Formula: see text]. Enhancement in the <span class="hlt">electron</span> <span class="hlt">transport</span> with increasing <span class="hlt">electron</span>-photon coupling is observed when [Formula: see text]. In this case the photon field dominates and stretches the <span class="hlt">electron</span> charge distribution in the quantum dot, extending it towards the contact area for the leads. Suppression in the <span class="hlt">electron</span> <span class="hlt">transport</span> is found when [Formula: see text], as the external magnetic field causes circular confinement of the charge density around the dot.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25680580','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25680580"><span id="translatedtitle">Induction events and short-term regulation of <span class="hlt">electron</span> <span class="hlt">transport</span> in chloroplasts: an overview.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Tikhonov, Alexander N</p> <p>2015-08-01</p> <p>Regulation of photosynthetic <span class="hlt">electron</span> <span class="hlt">transport</span> at different levels of structural and functional organization of photosynthetic apparatus provides efficient performance of oxygenic photosynthesis in plants. This review begins with a brief overview of the chloroplast <span class="hlt">electron</span> <span class="hlt">transport</span> chain. Then two noninvasive biophysical methods (measurements of slow induction of chlorophyll a fluorescence and EPR signals of oxidized P700 centers) are exemplified to illustrate the possibility of monitoring induction events in chloroplasts in vivo and in situ. Induction events in chloroplasts are considered and briefly discussed in the context of short-term mechanisms of the following regulatory processes: (i) pH-dependent control of the intersystem <span class="hlt">electron</span> <span class="hlt">transport</span>; (ii) the light-induced activation of the Calvin-Benson cycle; (iii) optimization of <span class="hlt">electron</span> <span class="hlt">transport</span> due to fitting alternative pathways of <span class="hlt">electron</span> flow and partitioning light energy between photosystems I and II; and (iv) the light-induced remodeling of photosynthetic apparatus and thylakoid membranes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/27420809','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/27420809"><span id="translatedtitle">Competition of static magnetic and dynamic photon forces in <span class="hlt">electronic</span> <span class="hlt">transport</span> through a quantum dot.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Rauf Abdullah, Nzar; Tang, Chi-Shung; Manolescu, Andrei; Gudmundsson, Vidar</p> <p>2016-09-21</p> <p>We investigate theoretically the balance of the static magnetic and the dynamical photon forces in the <span class="hlt">electron</span> <span class="hlt">transport</span> through a quantum dot in a photon cavity with a single photon mode. The quantum dot system is connected to external leads and the total system is exposed to a static perpendicular magnetic field. We explore the <span class="hlt">transport</span> characteristics through the system by tuning the ratio, [Formula: see text], between the photon energy, [Formula: see text], and the cyclotron energy, [Formula: see text]. Enhancement in the <span class="hlt">electron</span> <span class="hlt">transport</span> with increasing <span class="hlt">electron</span>-photon coupling is observed when [Formula: see text]. In this case the photon field dominates and stretches the <span class="hlt">electron</span> charge distribution in the quantum dot, extending it towards the contact area for the leads. Suppression in the <span class="hlt">electron</span> <span class="hlt">transport</span> is found when [Formula: see text], as the external magnetic field causes circular confinement of the charge density around the dot. PMID:27420809</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/19743502','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/19743502"><span id="translatedtitle">Mechanisms of membrane <span class="hlt">transport</span> of poorly soluble drugs: role of micelles in oral <span class="hlt">absorption</span> processes.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Yano, Koji; Masaoka, Yoshie; Kataoka, Makoto; Sakuma, Shinji; Yamashita, Shinji</p> <p>2010-03-01</p> <p>Micelles formed in the GI tract by bile acid and lecithin play an important role in oral <span class="hlt">absorption</span> of poorly soluble drugs. In this situation, the drug molecules are present in equilibrium between the free and micellar states. In this study, the relationship between the free drug concentration and the membrane permeability of poorly soluble drugs was examined. Permeability across a Caco-2 monolayer and a dialysis membrane were measured in a side-by-side chamber system. The concentrations of sodium taurocholate (NaTC) and lecithin were varied to allow measurement of membrane permeability at different concentrations of free drugs. For troglitazone, hexylparaben, and heptylparaben, an increase in the NaTC and lecithin concentrations caused the permeability across the Caco-2 monolayer to decrease slightly, whereas the permeability across the dialysis membrane decreased markedly. In contrast, the changes in permeability of griseofulvin with an increased micelle concentration were similar for the Caco-2 monolayer and the dialysis membrane. Assuming that the permeability for the dialysis membrane reflects the free drug concentration in the medium, these results suggest that troglitazone and alkylparabens, but not griseofulvin, can partition directly from micelles to Caco-2 monolayers. This mechanism may contribute to oral <span class="hlt">absorption</span> of drugs that are poorly soluble in water. PMID:19743502</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/27159495','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/27159495"><span id="translatedtitle">Simulation of Vacuum UV <span class="hlt">Absorption</span> and <span class="hlt">Electronic</span> Circular Dichroism Spectra of Methyl Oxirane: The Role of Vibrational Effects.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hodecker, Manuel; Biczysko, Malgorzata; Dreuw, Andreas; Barone, Vincenzo</p> <p>2016-06-14</p> <p>Vibrationally resolved one-photon <span class="hlt">absorption</span> and <span class="hlt">electronic</span> circular dichroism spectra of (R)-methyl oxirane were calculated with different <span class="hlt">electronic</span> and vibronic models selecting, through an analysis of the convergence of the results, the best compromise between reliability and computational cost. Linear-response TD-DFT/CAM-B3LYP/SNST <span class="hlt">electronic</span> computations in conjunction with the simple vertical gradient vibronic model were chosen and employed for systematic comparison with the available experimental data. Remarkable agreement between simulated and experimental spectra was achieved for both one-photon <span class="hlt">absorption</span> and circular dichroism concerning peak positions, relative intensities, and general spectral shapes considering the computational efficiency of the chosen theoretical approach. The significant improvement of the results with respect to smearing of vertical <span class="hlt">electronic</span> transitions by phenomenological Gaussian functions and the possible inclusion of solvent effects by polarizable continuum models at a negligible additional cost paves the route toward the simulation and analysis of spectral shapes of complex molecular systems in their natural environment. PMID:27159495</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19720018901','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19720018901"><span id="translatedtitle">Optical <span class="hlt">absorption</span> in fused silica at elevated temperatures during 1.5-MeV <span class="hlt">electron</span> irradiation</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Smith, A. B.</p> <p>1972-01-01</p> <p>An experimental determination of the optical transmission of Corning 7940 UV and Suprasil 1 and 2 fused silica has been made during 1.5-MeV <span class="hlt">electron</span> bombardment. The fused silica reached temperatures ranging from 150 to 1000 C. The Lewis Research Center dynamitron provided <span class="hlt">electron</span> current densities which corresponded to a dose rate of 2.6 to 20 Mrad/sec. The irradiation induced <span class="hlt">absorption</span> was measured at 215.0, 270.0, and 450.0 nm (2150, 2700, 4500 A). The length of each irradiation was sufficient so that an equilibrium between radiation induced coloration and high temperature annealing was reached. The experimental results indicate a significant optical <span class="hlt">absorption</span>, with values of the induced <span class="hlt">absorption</span> coefficient at 215.0 nm (2150 A) of 14.5 to 2.2/cm, at 270.0 nm (2700 A) of 9.7 to 3.0/cm and at 450.0 nm (4500 A) of 3.7 to 0.5/cm. This would make the use of fused silica as the separating wall material in the nuclear light bulb propulsion concept questionable.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/211608','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/211608"><span id="translatedtitle">Conceptual study of <span class="hlt">electron</span> ripple injection for tokamak <span class="hlt">transport</span> control</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Choe, W.; Ono, M.; Chang, C.S.</p> <p>1995-08-01</p> <p>A non-intrusive method for inducing radial electric field based on <span class="hlt">electron</span> ripple injection is under development by the Princeton CDX-U group. The radial electric field is known to play an important role in the L-H and H-VH mode transition according to the recent theoretical and experimental research. It is therefore important to develop a non-intrusive tool to control the radial electric field profile in tokamak plasmas. The present technique utilizes externally-applied local magnetic ripple fields to trap <span class="hlt">electrons</span> at the edge, allowing them to penetrate towards the plasma center via {gradient}B and curvature drifts, causing the flux surfaces to charge up negatively. <span class="hlt">Electron</span> cyclotron resonance heating is utilized to increase the trapped population and the <span class="hlt">electron</span> drift velocity by raising the perpendicular energy of trapped <span class="hlt">electrons</span>. In order to quantify the effects of cyclotron resonance heating on <span class="hlt">electrons</span>, the temperature anisotropy of resonant <span class="hlt">electrons</span> in a tokamak plasma is calculated. For the calculation of anisotropic temperatures, energy moments of the bounce-averaged Fokker-Planck equation with a bi-Maxwellian distribution function for heated <span class="hlt">electrons</span> are solved, assuming a moderate wave power and a constant quasilinear diffusion coefficient. Simulation using a guiding-center orbit model have been performed to understand the behavior of suprathermal <span class="hlt">electrons</span> in the presence of ripple fields. Examples for CDX-U and ITER parameters are given.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016SeScT..31k5004B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016SeScT..31k5004B"><span id="translatedtitle">Monte Carlo study of <span class="hlt">electron</span> <span class="hlt">transport</span> in monolayer silicene</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Borowik, Piotr; Thobel, Jean-Luc; Adamowicz, Leszek</p> <p>2016-11-01</p> <p><span class="hlt">Electron</span> mobility and diffusion coefficients in monolayer silicene are calculated by Monte Carlo simulations using simplified band structure with linear energy bands. Results demonstrate reasonable agreement with the full-band Monte Carlo method in low applied electric field conditions. Negative differential resistivity is observed and an explanation of the origin of this effect is proposed. <span class="hlt">Electron</span> mobility and diffusion coefficients are studied in low applied electric field conditions. We demonstrate that a comparison of these parameter values can provide a good check that the calculation is correct. Low-field mobility in silicene exhibits {T}-3 temperature dependence for nondegenerate <span class="hlt">electron</span> gas conditions and {T}-1 for higher <span class="hlt">electron</span> concentrations, when degenerate conditions are imposed. It is demonstrated that to explain the relation between mobility and temperature in nondegenerate <span class="hlt">electron</span> gas the linearity of the band structure has to be taken into account. It is also found that <span class="hlt">electron-electron</span> scattering only slightly modifies low-field <span class="hlt">electron</span> mobility in degenerate <span class="hlt">electron</span> gas conditions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19960021284&hterms=Energy+Solar+Wind&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DEnergy%2B%252B%2BSolar%2B%252B%2BWind','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19960021284&hterms=Energy+Solar+Wind&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DEnergy%2B%252B%2BSolar%2B%252B%2BWind"><span id="translatedtitle"><span class="hlt">Electron</span> energy <span class="hlt">transport</span> in the solar wind: Ulysses observations</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Scime, Earl; Gary, S. Peter; Phillips, J. L.; Corniileau-Wehrlin, N.; Solomon, J.</p> <p>1995-01-01</p> <p>The <span class="hlt">electron</span> heat flux in the solar wind has been measured by the Ulysses solar wind plasma experiment in the ecliptic from 1 to 5 AU and out of the ecliptic during the recently completed pass over the solar south pole and the ongoing pass over the solar north pole. Although the <span class="hlt">electron</span> heat flux contains only a fraction of the kinetic energy of the solar wind. the available energy is sufficient to account for the non-adiabatic expansion of the solar wind <span class="hlt">electrons</span>. The Ulysses measurements indicate that the <span class="hlt">electron</span> heat flux is actively dissipated in the solar wind. The exact mechanism or mechanisms is unknown. but a model based on the whistler heat flux instability predicts radial gradients for the <span class="hlt">electron</span> heat flux in good agreement with the data. We will present measurements of the correlation between wave activity measured by the unified radio and plasma experiment (URAP) and the <span class="hlt">electron</span> heat flux throughout the Ulysses mission. The goal is to determine if whistler waves are a good candidate for the observed <span class="hlt">electron</span> heat flux dissipation. The latitudinal gradients of the <span class="hlt">electron</span> heat flux. wave activity. and <span class="hlt">electron</span> pressure will be discussed in light of the changes in the magnetic field geometry from equator to poles.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li class="active"><span>24</span></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_24 --> <div id="page_25" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li class="active"><span>25</span></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="481"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2001JaJAP..40.7072F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2001JaJAP..40.7072F"><span id="translatedtitle"><span class="hlt">Electron</span> <span class="hlt">Transport</span> across Magnetic Filter in Negative Hydrogen Ion Source</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fukano, Azusa; Ogasawara, Masatada</p> <p>2001-12-01</p> <p>Profiles of <span class="hlt">electron</span> temperature and number density in a negative-ion source are investigated theoretically. Spatial dependence over the magnetic filter region is obtained using the equations of <span class="hlt">electron</span> flux and <span class="hlt">electron</span> heat flux that include the effect of interference of forces by the density gradient and temperature gradient. Due to the effect of the magnetic filter, temperature and density of the <span class="hlt">electron</span> decrease from the source chamber to the extraction chamber, and the decrease depends on the magnitude of the magnetic flux. The effect of the magnetic filter on the production and destruction rates of the negative hydrogen ion is examined. The reaction rate for the dissociative attachment reaction which produces the negative hydrogen ion increases with the decrease of the <span class="hlt">electron</span> temperature. However, the production rate per one vibrationally excited hydrogen molecule decreases with the decrease of <span class="hlt">electron</span> density. On the other hand, the destruction probability of the negative ion by the <span class="hlt">electron</span> detachment reaction decreases significantly by the decrease of the <span class="hlt">electron</span> density and temperature. The magnetic filter does not enhance the production of the negative hydrogen ion, but it reduces the destruction of the negative ion because of the decrease of the <span class="hlt">electron</span> density.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/11461406','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/11461406"><span id="translatedtitle">Observation of ultrahigh-energy <span class="hlt">electrons</span> by resonance <span class="hlt">absorption</span> of high-power microwaves in a pulsed plasma.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Rajyaguru, C; Fuji, T; Ito, H; Yugami, N; Nishida, Y</p> <p>2001-07-01</p> <p>The interaction of high power microwave with collisionless unmagnetized plasma is studied. Investigation on the generation of superthermal <span class="hlt">electrons</span> near the critical layer, by the resonance <span class="hlt">absorption</span> phenomenon, is extended to very high microwave power levels (eta=E(2)(0)/4 pi n(e)kT(e) approximately 0.3). Here E0, n(e), and T(e) are the vacuum electric field, <span class="hlt">electron</span> density, and <span class="hlt">electron</span> temperature, respectively. Successive generation of <span class="hlt">electron</span> bunches having maximum energy of about 2 keV, due to nonlinear wave breaking, is observed. The <span class="hlt">electron</span> energy epsilon scales as a function of the incident microwave power P, according to epsilon proportional to P0.5 up to 250 kW. The two-dimensional spatial distribution of high energy <span class="hlt">electrons</span> reveals that they are generated near the critical layer. However, the lower energy component is again produced in the subcritical density region indicating the possibility of other <span class="hlt">electron</span> heating mechanisms. PMID:11461406</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013ApPhL.103d1603W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013ApPhL.103d1603W"><span id="translatedtitle">The effect of <span class="hlt">electron</span> induced hydrogenation of graphene on its electrical <span class="hlt">transport</span> properties</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Woo, Sung Oh; Teizer, Winfried</p> <p>2013-07-01</p> <p>We report a deterioration of the electrical <span class="hlt">transport</span> properties of a graphene field effect transistor due to energetic <span class="hlt">electron</span> irradiation on a stack of Poly Methyl Methacrylate (PMMA) on graphene (PMMA/graphene bilayer). Prior to <span class="hlt">electron</span> irradiation, we observed that the PMMA layer on graphene does not deteriorate the carrier <span class="hlt">transport</span> of graphene but improves its electrical properties instead. As a result of the <span class="hlt">electron</span> irradiation on the PMMA/graphene bilayer, the Raman "D" band appears after removal of PMMA. We argue that the degradation of the <span class="hlt">transport</span> behavior originates from the binding of hydrogen generated during the PMMA backbone secession process.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013MPLB...2750175L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013MPLB...2750175L"><span id="translatedtitle">The <span class="hlt">Electron</span> <span class="hlt">Transport</span> in a Nanostructure Modulated by the Magnetic Field and the δ-DOPING</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lu, Jian-Duo; Xu, Bin; Zheng, Wei</p> <p>2013-09-01</p> <p>We theoretically investigate the effect of the δ-doping on the <span class="hlt">electron</span> <span class="hlt">transport</span> in a magnetic nanostructure, which can be experimentally realized by depositing one ferromagnetic stripe on the top of a semiconductor heterostructure. We find that the position and the strength of the δ-doping as well as the distance between the two magnetic fields play an important role on the <span class="hlt">electron</span> <span class="hlt">transport</span> properties such as the transmission probability, the conductance and the spin polarization. These interesting results may be very helpful for analyzing the spin-dependent <span class="hlt">transport</span> mechanism of the <span class="hlt">electron</span> and making the new types of the spintronic devices.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011ApJ...728..133T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011ApJ...728..133T"><span id="translatedtitle">What Causes Scatter-free <span class="hlt">Transport</span> of Non-relativistic Solar <span class="hlt">Electrons</span>?</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tan, Lun C.; Reames, Donald V.; Ng, Chee K.; Shao, Xi; Wang, Linghua</p> <p>2011-02-01</p> <p>We have examined the cause of the scatter-free <span class="hlt">transport</span> of non-relativistic solar <span class="hlt">electrons</span>. <span class="hlt">Electron</span> scatter-free <span class="hlt">transport</span> events are compared with the diffusive <span class="hlt">transport</span> event. The emphasis of our examination is on the energy dependence of <span class="hlt">electron</span> angular distributions and the steepening of interplanetary magnetic field (IMF) power spectral densities (PSDs). Near and above the proton gyrofrequency, the effects of both R-mode (whistler) and L-mode (electromagnetic ion cyclotron, EMIC) waves need to be taken into account separately. The PSD spectral steepening due to the EMIC wave damping by solar-wind thermal ions becomes essential. In a fast-rise-fast-decay impulsive <span class="hlt">electron</span> event we have observed such steepening, which significantly reduces PSD levels at frequencies above the proton gyrofrequency. The spectral steepening thus produced favors the occurrence of scatter-free <span class="hlt">transport</span> of low-energy <span class="hlt">electrons</span>. Consequently, within the Wind/3D Plasma and Energetic Particle Instrument/Silicon Semiconductor Telescope measured energy range (~25-500 keV), there appears to be an <span class="hlt">electron</span> energy window, across which the scatter-free <span class="hlt">transport</span> of lower energy <span class="hlt">electrons</span> would change to the diffusive <span class="hlt">transport</span> of higher energy <span class="hlt">electrons</span>. We have observed such a change and found it is correlated with the occurrence of broken power-law spectra of <span class="hlt">electrons</span>. Thus the connection between the transition from diffusive to scatter-free <span class="hlt">electron</span> <span class="hlt">transport</span> and the concurrent transition from high to low IMF PSD levels with corresponding breaks in the <span class="hlt">electron</span> power-law energy spectrum and PSD spectrum has been recognized.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016CoPhC.203..268R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016CoPhC.203..268R"><span id="translatedtitle">METHES: A Monte Carlo collision code for the simulation of <span class="hlt">electron</span> <span class="hlt">transport</span> in low temperature plasmas</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rabie, M.; Franck, C. M.</p> <p>2016-06-01</p> <p>We present a freely available MATLAB code for the simulation of <span class="hlt">electron</span> <span class="hlt">transport</span> in arbitrary gas mixtures in the presence of uniform electric fields. For steady-state <span class="hlt">electron</span> <span class="hlt">transport</span>, the program provides the <span class="hlt">transport</span> coefficients, reaction rates and the <span class="hlt">electron</span> energy distribution function. The program uses established Monte Carlo techniques and is compatible with the <span class="hlt">electron</span> scattering cross section files from the open-access Plasma Data Exchange Project LXCat. The code is written in object-oriented design, allowing the tracing and visualization of the spatiotemporal evolution of <span class="hlt">electron</span> swarms and the temporal development of the mean energy and the <span class="hlt">electron</span> number due to attachment and/or ionization processes. We benchmark our code with well-known model gases as well as the real gases argon, N2, O2, CF4, SF6 and mixtures of N2 and O2.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/22041897','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/22041897"><span id="translatedtitle">Monosaccharide <span class="hlt">absorption</span> activity of Arabidopsis roots depends on expression profiles of <span class="hlt">transporter</span> genes under high salinity conditions.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Yamada, Kohji; Kanai, Motoki; Osakabe, Yuriko; Ohiraki, Haruka; Shinozaki, Kazuo; Yamaguchi-Shinozaki, Kazuko</p> <p>2011-12-16</p> <p>Plant roots are able to absorb sugars from the rhizosphere but also release sugars and other metabolites that are critical for growth and environmental signaling. Reabsorption of released sugar molecules could help reduce the loss of photosynthetically fixed carbon through the roots. Although biochemical analyses have revealed monosaccharide uptake mechanisms in roots, the <span class="hlt">transporters</span> that are involved in this process have not yet been fully characterized. In the present study we demonstrate that Arabidopsis STP1 and STP13 play important roles in roots during the <span class="hlt">absorption</span> of monosaccharides from the rhizosphere. Among 14 STP <span class="hlt">transporter</span> genes, we found that STP1 had the highest transcript level and that STP1 was a major contributor for monosaccharide uptake under normal conditions. In contrast, STP13 was found to be induced by abiotic stress, with low expression under normal conditions. We analyzed the role of STP13 in roots under high salinity conditions where membranes of the epidermal cells were damaged, and we detected an increase in the amount of STP13-dependent glucose uptake. Furthermore, the amount of glucose efflux from stp13 mutants was higher than that from wild type plants under high salinity conditions. These results indicate that STP13 can reabsorb the monosaccharides that are released by damaged cells under high salinity conditions. Overall, our data indicate that sugar uptake capacity in Arabidopsis roots changes in response to environmental stresses and that this activity is dependent on the expression pattern of sugar <span class="hlt">transporters</span>. PMID:22041897</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/367109','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/367109"><span id="translatedtitle"><span class="hlt">Electron</span> ripple injection concept for tokamak <span class="hlt">transport</span> control</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Choe, W.; Ono, M.; Chang, C.S.</p> <p>1996-02-01</p> <p>A non-intrusive method for inducing a radial electric field ({ital E}{sub {ital r}}) based on <span class="hlt">electron</span> ripple injection (ERI) is under development by the Princeton CDX-U group. Since {ital E}{sub {ital r}} is known to play an important role in the L-H and H-VH mode transition, it is therefore important to develop a non-intrusive tool to control the {ital E}{sub {ital r}} profile in tokamak plasmas. The present technique utilizes externally-applied local magnetic ripple fields to trap <span class="hlt">electrons</span> at the edge, allowing them to penetrate towards the plasma center via {nabla}{ital B} and curvature drifts, causing the flux surfaces to charge up negatively. <span class="hlt">Electron</span> cyclotron resonance heating (ECRH) is utilized to increase the trapped population and the <span class="hlt">electron</span> drift velocity by raising the perpendicular energy of trapped <span class="hlt">electrons</span>. The temperature anisotropy of resonant <span class="hlt">electrons</span> in a tokamak plasma is calculated in order to investigate effects of ECRH on <span class="hlt">electrons</span>. Simulations using a guiding-center orbit model have been performed to understand the behavior of suprathermal <span class="hlt">electrons</span> in the presence of ripple fields. Examples for CDX-U and ITER are given. {copyright} {ital 1996 American Institute of Physics.}</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1214334','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1214334"><span id="translatedtitle">Operando X-ray <span class="hlt">absorption</span> and EPR evidence for a single <span class="hlt">electron</span> redox process in copper catalysis</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Lu, Qingquan; Zhang, Jian; Peng, Pan; Zhang, Guanghui; Huang, Zhiliang; Yi, Hong; Miller, Jeffrey T.; Lei, Aiwen</p> <p>2015-05-26</p> <p>An unprecedented single <span class="hlt">electron</span> redox process in copper catalysis is confirmed using operando X-ray <span class="hlt">absorption</span> and EPR spectroscopies. The oxidation state of the copper species in the interaction between Cu(II) and a sulfinic acid at room temperature, and the accurate characterization of the formed Cu(I) are clearly shown using operando X-ray <span class="hlt">absorption</span> and EPR evidence. Further investigation of anion effects on Cu(II) discloses that bromine ions can dramatically increase the rate of the redox process. Moreover, it is proven that the sulfinic acids are converted into sulfonyl radicals, which can be trapped by 2-arylacrylic acids and various valuable β-keto sulfones are synthesized with good to excellent yields under mild conditions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/pages/biblio/1214334-operando-ray-absorption-epr-evidence-single-electron-redox-process-copper-catalysis','SCIGOV-DOEP'); return false;" href="http://www.osti.gov/pages/biblio/1214334-operando-ray-absorption-epr-evidence-single-electron-redox-process-copper-catalysis"><span id="translatedtitle">Operando X-ray <span class="hlt">absorption</span> and EPR evidence for a single <span class="hlt">electron</span> redox process in copper catalysis</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Lu, Qingquan; Zhang, Jian; Peng, Pan; Zhang, Guanghui; Huang, Zhiliang; Yi, Hong; Miller, Jeffrey T.; Lei, Aiwen</p> <p>2015-05-26</p> <p>An unprecedented single <span class="hlt">electron</span> redox process in copper catalysis is confirmed using operando X-ray <span class="hlt">absorption</span> and EPR spectroscopies. The oxidation state of the copper species in the interaction between Cu(II) and a sulfinic acid at room temperature, and the accurate characterization of the formed Cu(I) are clearly shown using operando X-ray <span class="hlt">absorption</span> and EPR evidence. Further investigation of anion effects on Cu(II) discloses that bromine ions can dramatically increase the rate of the redox process. Moreover, it is proven that the sulfinic acids are converted into sulfonyl radicals, which can be trapped by 2-arylacrylic acids and various valuable β-keto sulfonesmore » are synthesized with good to excellent yields under mild conditions.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23030098','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23030098"><span id="translatedtitle">Ambipolar <span class="hlt">transport</span> via trapped-<span class="hlt">electron</span> whistler instability along open magnetic field lines.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Guo, Zehua; Tang, Xian-Zhu</p> <p>2012-09-28</p> <p>An open field line plasma is bounded by a chamber wall which intercepts the magnetic field. Steady state requires an upstream plasma source balancing the particle loss to the boundary. In cases where the <span class="hlt">electrons</span> have a long mean free path, ambipolarity in parallel <span class="hlt">transport</span> critically depends on collisionless detrapping of the <span class="hlt">electrons</span> via wave-particle interaction. The trapped-<span class="hlt">electron</span> whistler instability, whose nonlinear saturation produces a spectrum of whistler waves that is responsible for the <span class="hlt">electron</span> detrapping flux, is shown to be an unusually robust kinetic instability, which is essential to the universality of the ambipolar constraint in plasma <span class="hlt">transport</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2004PPCF...46A..71I&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2004PPCF...46A..71I&link_type=ABSTRACT"><span id="translatedtitle">Cold pulse experiments in plasma with an <span class="hlt">electron</span> internal <span class="hlt">transport</span> barrier on LHD</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Inagaki, S.; Ida, K.; Tamura, N.; Shimozuma, T.; Kubo, S.; Nagayama, Y.; Kawahata, K.; Sudo, S.; Ohkubo, K.; LHD Experimental Group</p> <p>2004-05-01</p> <p>Transient <span class="hlt">transport</span> experiments are performed in LHD plasma with <span class="hlt">electron</span> internal <span class="hlt">transport</span> barrier (e-ITB). Evidence for a reduction of <span class="hlt">electron</span> heat diffusivity inside the ITB is observed from cold and heat pulse propagations. The observed enhancement of the cold pulse peak is explained by the temperature dependent <span class="hlt">electron</span> heat diffusivity. The heat diffusivity inside the ITB decreases with an increase in the <span class="hlt">electron</span> temperature in LHD. A preliminary version of this study was presented in the 29th EPS Conf. on Plasma Phys. and Control. Fusion (Montreux, Switzerland, 17 21 June 2002) [1].</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26710632','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26710632"><span id="translatedtitle">[Effect of atmospheric CO2 concentration and nitrogen application level on <span class="hlt">absorption</span> and <span class="hlt">transportation</span> of nutrient elements in oilseed rape].</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wang, Wen-ming; Zhang, Zhen-hua; Song, Hai-xing; Liu, Qiang; Rong, Xiang-min; Guan, Chun-yun; Zeng, Jing; Yuan, Dan</p> <p>2015-07-01</p> <p>Effect of elevated atmospheric-CO2 (780 µmol . mol-1) on the <span class="hlt">absorption</span> and <span class="hlt">transportation</span> of secondary nutrient elements (calcium, magnesium, sulphur) and micronutrient elements (iron, manganese, zinc, molybdenum and boron) in oilseed rape at the stem elongation stage were studied by greenhouse simulated method. Compared with the ambient CO2 condition, the content of Zn in stem was increased and the contents of other nutrient elements were decreased under the elevated atmospheric-CO2 with no nitrogen (N) application; the contents of Ca, S, B and Zn were increased, and the contents of Mg, Mn, Mo and Fe were decreased under the elevated atmospheric CO2 with N application (0.2 g N . kg-1 soil); except the content of Mo in leaf was increased, the contents of other nutrient elements were decreased under the elevated atmospheric-CO2 with two levels of N application. Compared with the ambient CO2 condition, the amounts of Ca and S relative to the total amount of secondary nutrient elements in stem and the amounts of B and Zn relative to the total amount of micronutrient elements in stem were increased under the elevated-CO2 treatment with both levels of N application, and the corresponding values of Mg, Fe, Mn and Mo were decreased; no-N application treatment increased the proportion of Ca distributed into the leaves, and the proportion of Mg distributed into leaves was increased by the normal-N application level; the proportions of Mn, Zn and Mo distributed into the leaves were increased at both N application levels. Without N application, the elevation of atmospheric CO2 increased the <span class="hlt">transport</span> coefficients of SFe, Mo and SS,B, but decreased the <span class="hlt">transport</span> coefficients of SMg,Fe, SMg, Mn and SS,Fe, indicating the proportions of Mo, S <span class="hlt">transported</span> into the upper part of plant tissues was higher than that of Fe, and the corresponding value of B was higher than that observed for S, the corresponding value of Mg was higher than that of Fe and Mn. Under normal-N application</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26710632','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26710632"><span id="translatedtitle">[Effect of atmospheric CO2 concentration and nitrogen application level on <span class="hlt">absorption</span> and <span class="hlt">transportation</span> of nutrient elements in oilseed rape].</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wang, Wen-ming; Zhang, Zhen-hua; Song, Hai-xing; Liu, Qiang; Rong, Xiang-min; Guan, Chun-yun; Zeng, Jing; Yuan, Dan</p> <p>2015-07-01</p> <p>Effect of elevated atmospheric-CO2 (780 µmol . mol-1) on the <span class="hlt">absorption</span> and <span class="hlt">transportation</span> of secondary nutrient elements (calcium, magnesium, sulphur) and micronutrient elements (iron, manganese, zinc, molybdenum and boron) in oilseed rape at the stem elongation stage were studied by greenhouse simulated method. Compared with the ambient CO2 condition, the content of Zn in stem was increased and the contents of other nutrient elements were decreased under the elevated atmospheric-CO2 with no nitrogen (N) application; the contents of Ca, S, B and Zn were increased, and the contents of Mg, Mn, Mo and Fe were decreased under the elevated atmospheric CO2 with N application (0.2 g N . kg-1 soil); except the content of Mo in leaf was increased, the contents of other nutrient elements were decreased under the elevated atmospheric-CO2 with two levels of N application. Compared with the ambient CO2 condition, the amounts of Ca and S relative to the total amount of secondary nutrient elements in stem and the amounts of B and Zn relative to the total amount of micronutrient elements in stem were increased under the elevated-CO2 treatment with both levels of N application, and the corresponding values of Mg, Fe, Mn and Mo were decreased; no-N application treatment increased the proportion of Ca distributed into the leaves, and the proportion of Mg distributed into leaves was increased by the normal-N application level; the proportions of Mn, Zn and Mo distributed into the leaves were increased at both N application levels. Without N application, the elevation of atmospheric CO2 increased the <span class="hlt">transport</span> coefficients of SFe, Mo and SS,B, but decreased the <span class="hlt">transport</span> coefficients of SMg,Fe, SMg, Mn and SS,Fe, indicating the proportions of Mo, S <span class="hlt">transported</span> into the upper part of plant tissues was higher than that of Fe, and the corresponding value of B was higher than that observed for S, the corresponding value of Mg was higher than that of Fe and Mn. Under normal-N application</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/22028007','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22028007"><span id="translatedtitle"><span class="hlt">Absorption</span> of gamma-ray photons in a vacuum neutron star magnetosphere: I. <span class="hlt">Electron</span>-positron pair production</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Istomin, Ya. N. Sob'yanin, D. N.</p> <p>2011-10-15</p> <p>The production of <span class="hlt">electron</span>-positron pairs in a vacuum neutron star magnetosphere is investigated for both low (compared to the Schwinger one) and high magnetic fields. The case of a strong longitudinal electric field where the produced <span class="hlt">electrons</span> and positrons acquire a stationary Lorentz factor in a short time is considered. The source of <span class="hlt">electron</span>-positron pairs has been calculated with allowance made for the pair production by curvature and synchrotron photons. Synchrotron photons are shown to make a major contribution to the total pair production rate in a weak magnetic field. At the same time, the contribution from bremsstrahlung photons may be neglected. The existence of a time delay due to the finiteness of the <span class="hlt">electron</span> and positron acceleration time leads to a great reduction in the <span class="hlt">electron</span>-positron plasma generation rate compared to the case of a zero time delay. The effective local source of <span class="hlt">electron</span>-positron pairs has been constructed. It can be used in the hydrodynamic equations that describe the development of a cascade after the <span class="hlt">absorption</span> of a photon from the cosmic gamma-ray background in a neutron star magnetosphere.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/574650','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/574650"><span id="translatedtitle"><span class="hlt">Electron</span> energy <span class="hlt">transport</span> in the solar wind: Ulysses observations</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Scime, E.E.; Gary, S.P.; Phillips, J.L.; Balogh, A.; Lengyel-Frey, D.</p> <p>1996-07-01</p> <p>Previous analysis suggests that the whistler heat flux instability is responsible for the regulation of the <span class="hlt">electron</span> heat flux of the solar wind. For an interval of quiescent solar wind during the in-ecliptic phase of the Ulysses mission, the plasma wave data in the whistler frequency regime are compared to the predictions of the whistler heat flux instability model. The data is well constrained by the predicted upper bound on the <span class="hlt">electron</span> heat flux and a clear correlation between wave activity and <span class="hlt">electron</span> heat flux dissipation is observed. {copyright} {ital 1996 American Institute of Physics.}</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/21163474','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/21163474"><span id="translatedtitle"><span class="hlt">Electron</span> energy <span class="hlt">transport</span> in the solar wind: Ulysses observations</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Scime, Earl E.; Gary, S. Peter; Phillips, John L.; Balogh, Andre; Lengyel-Frey, Denise</p> <p>1996-07-20</p> <p>Previous analysis suggests that the whistler heat flux instability is responsible for the regulation of the <span class="hlt">electron</span> heat flux of the solar wind. For an interval of quiescent solar wind during the in-ecliptic phase of the Ulysses mission, the plasma wave data in the whistler frequency regime are compared to the predictions of the whistler heat flux instability model. The data is well constrained by the predicted upper bound on the <span class="hlt">electron</span> heat flux and a clear correlation between wave activity and <span class="hlt">electron</span> heat flux dissipation is observed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009AnGeo..27.2173U','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009AnGeo..27.2173U"><span id="translatedtitle">Radial <span class="hlt">transport</span> of radiation belt <span class="hlt">electrons</span> due to stormtime Pc5 waves</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ukhorskiy, A. Y.; Sitnov, M. I.; Takahashi, K.; Anderson, B. J.</p> <p>2009-05-01</p> <p>During geomagnetic storms relativistic <span class="hlt">electron</span> fluxes in the outer radiation belt exhibit dynamic variability over multiple orders of magnitude. This requires radial <span class="hlt">transport</span> of <span class="hlt">electrons</span> across their drift shells and implies violation of their third adiabatic invariant. Radial <span class="hlt">transport</span> is induced by the interaction of the <span class="hlt">electron</span> drift motion with electric and magnetic field fluctuations in the ULF frequency range. It was previously shown that solar-wind driven ULF waves have long azimuthal wave lengths and thus can violate the third invariant of trapped <span class="hlt">electrons</span> in the process of resonant interaction with their gradient-curvature motion. However, the amplitude of solar-wind driven ULF waves rapidly decreases with decreasing L. It is therefore not clear what mechanisms are responsible for fast <span class="hlt">transport</span> rates observed inside the geosynchronous orbit. In this paper we investigate wether stormtime Pc5 waves can contribute to this process. Stormtime Pc5s have short azimuthal wave lengths and therefore cannot exhibit resonance with the the <span class="hlt">electron</span> drift motion. However we show that stormtime Pc5s can cause localized random scattering of <span class="hlt">electron</span> drift motion that violates the third invariant. According to our results <span class="hlt">electron</span> interaction with stormtime Pc5s can produce rapid radial <span class="hlt">transport</span> even as low as L≃4. Numerical simulations show that <span class="hlt">electron</span> <span class="hlt">transport</span> can exhibit large deviations from radial diffusion. The diffusion approximation is not valid for individual storms but only applies to the statistically averaged response of the outer belt to stormtime Pc5 waves.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2010-title41-vol3/pdf/CFR-2010-title41-vol3-sec102-118-80.pdf','CFR'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2010-title41-vol3/pdf/CFR-2010-title41-vol3-sec102-118-80.pdf"><span id="translatedtitle">41 CFR 102-118.80 - Who is responsible for keeping my agency's <span class="hlt">electronic</span> commerce <span class="hlt">transportation</span> billing records?</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2010&page.go=Go">Code of Federal Regulations, 2010 CFR</a></p> <p></p> <p>2010-07-01</p> <p>... keeping my agency's <span class="hlt">electronic</span> commerce <span class="hlt">transportation</span> billing records? 102-118.80 Section 102-118.80... <span class="hlt">Transportation</span> and <span class="hlt">Transportation</span> Services § 102-118.80 Who is responsible for keeping my agency's <span class="hlt">electronic</span> commerce <span class="hlt">transportation</span> billing records? Your agency's internal financial regulations will...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/22402591','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22402591"><span id="translatedtitle">Reversible modulation of electric <span class="hlt">transport</span> properties by oxygen <span class="hlt">absorption</span> and releasing on Nb:SrTiO{sub 3} surface</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Lu, H. X.; Liu, Y. B.; Chen, Y. S. Wang, J.; Shen, B. G.; Sun, J. R.</p> <p>2014-11-07</p> <p>Pt Schottky contacts on (001)-orientated Nb-doped SrTiO{sub 3} (NSTO) in both ambient air and vacuum were investigated by the conductive atomic force microscope. The co-existed TiO{sub 2} and SrO termination layers were identified on the terrace-structured NSTO surface, where the former possessed a higher forward current than the latter. In ambient air, the barrier height of Pt/NSTO Schottky junction exhibited periodical variation with cyclic terrace plane and step sites, whereas it became homogeneous in ambient vacuum. We suggested that the oxygen <span class="hlt">absorption</span> and releasing of surface dangling bonds were the origin for reversible changes in <span class="hlt">transport</span> properties, which indicates a feasible approach for the surface modulation and band structure tailoring of NSTO based heterojunctions.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li class="active"><span>25</span></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_25 --> <center> <div class="footer-extlink text-muted"><small>Some links on this page may take you to non-federal websites. 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